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The present work reports the influence of the presence of different ions (Cl-, Br-, NO3-, or SO42-) on the formation and proprieties of Cu(II) complexes with pyridoxal-benzoylhydrazone (PLBHZ). Four new complexes were successfully synthesized, [CuCl2(PLBHZ)] (1), [CuBr2(PLBHZ)] (2), [CuCl(PLBHZ)H2O]-NO3-H2O (3), and [CuSO4(PLBHZ)H2O]-3H2O (4), and characterized by spectroscopic and physicochemical methods. A single-crystal X-ray study reveals the Schiff base coordinated to the metal center tridentate by the ONS-donor system, resulting in distorted square pyramidal coordination geometries. Noncovalent interactions were investigated by 3D Hirshfeld surface analysis by the dnorm function, 2D fingerprint plots, and full interaction maps. The ion exchange is important in forming three-dimensional networks with π···π stacking interactions and intermolecular hydrogen bonds. The in vitro biological activity of the free ligand and metal complexes was evaluated against Gram-positive and Gramnegative bacterial strains and the free pyridoxal-hydrazone ligand showed higher activity than their Cu(II) complexes. Molecular docking was used to predict the inhibitory activity of the ligand and complexes against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. [ABSTRACT FROM AUTHOR]

Efficiently constructing structures with high thermal stability is a key objective in the development of energetic compounds. However, the existing synthesis processes for heat‐resistant energetic materials are frequently hampered by their complexity and low yields. This study presents a significant breakthrough in addressing these challenges. It successfully synthesizes 4‐amino‐5‐(3‐amino‐1H‐pyrazole‐4‐yl)‐2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐one (APTO) using a streamlined two‐step process, achieving an impressive high yield of 87.5 %. The structure was determined through X‐ray single crystal diffraction analysis, revealing a nearly planar intramolecular structure. Hirshfeld surface analysis, weak interaction analysis, and aromaticity analysis were conducted, illustrating a substantial presence of hydrogen bonds and π ‐ π stacking interactions within and between molecules. These interactions contribute significantly to exceptional thermal stability of ATPO. Furthermore, the thermal stability of ATPO was confirmed through DSC analysis, exhibiting a decomposition temperature as high as 365.2°C. This temperature surpasses that of the heat‐resistant explosive HNS (325°C), further validating its excellent thermal stability. The construction of this conjugated structure offers valuable guidance for the future structural design of heat‐resistant energetic materials. It opens up possibilities for the development of novel compounds with improved thermal stability based on similar conjugated architectures. [ABSTRACT FROM AUTHOR]

A quinoline-containing semi-salamo-type ligand, HL, was synthesized and a dinuclear Ni(II) complex, [Ni2(L)2(NCS)2], was produced. The complex was experimentally analyzed by elemental analysis, fluorescence, and UV–Vis spectroscopy. X-ray single crystal diffraction experiments showed that the complex is a six-coordinate, structurally symmetric, phenoxy-bridged dinuclear Ni(II) dimer with the participation of SCN− in the coordination to satisfy charge neutrality. The self-assembly forms a 2-D supramolecular network structure through hydrogen bonding and π⋯π interactions. DFT calculations were performed on the complex to analyze its energy gaps, and UV–Vis experiment was verified by TD-DFT calculation. In addition, close intermolecular contacts were investigated by Hirshfeld surface analysis to quantify the crystal structure interaction. [ABSTRACT FROM AUTHOR]

Centrosymmetric homopolynuclear Cu(II) and Co(II) chelated complexes, [Cu2(L)(H2O)2] (1) and [Co4(L)(μ-OAc)2(CH3OH)4(OAC)2]⋅2CH2Cl2 (2), were synthesized using a new symmetrical methoxy-disubstituted bis(salamo)-type ligand, H4L, with Cu(II) and Co(II) salts in organic solvents. Complexes 1 and 2 were structurally characterized by single-crystal X-ray crystallography. The results indicated that 1 is a five-coordinate dinuclear structure containing Cu(II) and 2 is a tetranuclear Co(II) complex with two distinct six-coordinate environments. Furthermore, 1 and 2 pack into three-dimensional and two-dimensional extended networks, respectively. The UV–Vis spectra, IR spectra, and Hirshfeld surface analyses of the complexes were carried out to further characterize the coordination between H4L and the metal(II) ions. Fluorescence methods were used to interrogate the coordination, where changes in emission with varied amounts of ligand supported solution-phase coordination ratios of H4L with Cu(II) ion of 1:2 and with Co(II) ion of 1:4, respectively. [ABSTRACT FROM AUTHOR]

New di- and tetranuclear Cu(II) complexes, [Cu2(HL)Cl2(MeOH)]·MeOH·2CH2Cl2 (1) and [Cu4(L)2(MeOH)2](NO3)2·EtOH (2), have been synthesized from CuCl2·2H2O, Cu(NO3)2·3H2O and a symmetric 5-bromosalicylaldehyde-decorated bis(salamo)-like ligand (H3L, (1E,3E)-2-hydroxy-5-methylisophthalaldehyde O,O-di(2-((((E)-5-bromo-2-hydroxybenzylidene)amino)-oxy)ethyl)dioxime), and characterized by elemental analyses, IR and UV–vis spectra. Single crystal structure analyses showed a dinuclear Cu(II) structure for 1 and a tetranuclear Cu(II) structure for 2. In 1, two Cu(II) ions are on one side of the double N2O2 cavities, and the phenol proton in the other cavity is attached. In 2, four Cu(II) ions are located in four N2O2 cavities of two fully deprotonated L3− units, giving a centrosymmetric double helix structure. The Hirshfeld surfaces analyses, Interaction Region Indicator (IRI), and DFT computations of H3L, 1, and 2 were studied. In addition, the electrochemical and fluorescence properties of 1 and 2 were also investigated. [ABSTRACT FROM AUTHOR]

In order to broaden the study of energetic cations, a cation 3,5-diamino-4H-pyrazol-4-one oxime (DAPO) with good thermal stability was proposed, and its three salts were synthesized by a simple and efficient method. The structures of the three salts were verified by infrared spectroscopy, mass spectrometry, elemental analysis, and single crystal X-ray diffraction. The thermal stabilities of the three salts were verified by differential scanning calorimetry and thermos-gravimetric analysis. DAPO-based energetic salts are analysed using a variety of theoretical techniques, such as 2D fingerprint, Hirshfeld surface, and non-covalent interaction. Among them, the energy properties of perchlorate (DAPOP) and picrate (DAPOT) were determined by EXPLO5 program combined with the measured density and enthalpy of formation. These compounds have high density, acceptable detonation performance, good thermal stability, and satisfactory sensitivity. The intermolecular interactions of the four compounds were studied by Hirshfeld surface and non-covalent interactions, indicating that hydrogen bonds and π–π stacking interactions are the reasons for the extracellular properties of perchlorate (DAPOP) and picrate (DAPOT), indicating that DAPO is an optional nitrogen-rich cation for the design and synthesis of novel energetic materials with excellent properties. [ABSTRACT FROM AUTHOR]

A penta-coordinated dinuclear Zn(II) complex, [Zn2(L)(μ-PhCOO)(EtOH)] (1), and a hexa-coordinate tetranuclear Cd(II) complex, [{Cd2(L)(EtOH)(η-OAc)}2]·2CH2Cl2 (2), have been synthesized by reactions of a single-armed salamo-based ligand, H3L, and two kinds of transition metal salts, (Zn(NO3)2·6H2O and Cd(OAc)2·2H2O), respectively. Complexes 1 and 2 have been characterized by elemental analyses, single crystal X-ray diffraction, IR spectra and UV-Vis spectra. Complex 1 is composed of a totally deprotonated ligand (L)3- moiety, two Zn(II) ions, one μ-PhCOO- counter-anion and one coordinated ethanol molecule. The (L)3- unit packages two Zn(II) ions, the μ-PhCOO- counter-anion bridges two adjacent Zn(II) ions and one ethanol molecule coordinates with the Zn2 ion, so that both Zn(II) ions are penta-coordinated with slightly distorted trigonal bipyramidal configurations, and the τ5 values of Zn1 and Zn2 are 0.86 and 0.65, respectively. Complex 2 consists of two discrete and similar electroneutral tetra-nuclear units, 2 A and 2B, and two crystallized dichloromethane molecules. Each unit has a symmetric structure that is made up of two completely deprotonated ligand (L)3- moieties, four Cd(II) ions, two η-OAc- counter-anions and two coordinated ethanol molecules. Fluorescence properties and Hirshfeld surfaces analyses have been studied as well. [ABSTRACT FROM AUTHOR]

Two mixed-valence Co(II)/Co(III) complexes of [CoII(phen)3][CoIII(HATD)2]2·3DMA·3.5H2O (1), and [CoII(terpy)2][CoIII(HATD)2]2·4DMA·H2O (2), (phen = 1,10-phenanthroline, terpy = 2,2′:6′,2′′-terpyridine, H3ATD = azotetrazolyl-2,7-dihydroxynaphthalene, DMA = N,N-dimethylacetamide) were synthesized and their crystal structures were characterized. Crystal structure analyses reveal that complexes 1 and 2 consist of CoIII and CoII ions in an octahedral environment where the CoII ion is coordinated by three phen ligands and two terpy ligands, respectively. Magnetic measurements show that complex 1 displays field induced single-molecule magnet behavior, whereas 2 undergoes a gradual thermal spin crossover (SCO). [ABSTRACT FROM AUTHOR]

The coordination behaviors of asymmetric quinoline-decorated half-salamo-type ligand HL1 with Cu(NO3)2·3H2O and Cu(OAc)2·H2O were studied. Two Cu(II) complexes, [Cu(L1)(NO3)]·CH3CH2OH (1) and [Cu2(L2)2] (2), were isolated and characterized by X-ray crystallography, FTIR, UV–vis, and fluorescence spectroscopies. Structural analyses showed that 1 is a mononuclear species, whereas 2 is a binuclear entity. Spontaneous cleavage along the oxime N-O bond close to quinoline ring of the ligand HL1 occurred upon reaction with Cu(OAc)2·H2O, yielding an unexpected complex 2. Moreover, DFT theoretical calculations and Hirshfeld surfaces analyses of the ligand HL1 and its corresponding Cu(II) complexes were investigated in detail. [ABSTRACT FROM AUTHOR]

Two structurally different Cu(II) and Co(II) complexes, [Cu(L)] (1) and [Co2(L)2]⋅2CH3OH (2), constructed from a new polyhalogen-substituted unsymmetric salamo-based ligand (H2L, 4-chloro-4′-bromo-6-bromo-6′-tert-butyl-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol) were synthesized by wet-chemical methods. Complexes 1 and 2 were characterized through elemental analyses, IR and UV-vis spectroscopies and single crystal X-ray crystallography. In addition, the differences of the structures, electronic absorption characteristics and fluorescence property transitions from the ligand to complexes 1 and 2 were studied. The largest difference is that the ligand H2L can react with M(OAc)2 (M = Cu(II) and Co(II)) to give two complexes with distinct structures and behaviors. There are two chemically identical but crystallographically independent structural units (molecules A and B) in 1. Moreover, each Cu(II) ion (Cu1 or Cu2) is four-coordinate and possesses a square planar geometry, but both Co(II) ions of 2 are bridged by phenoxide ions and possess five-coordinate trigonal bipyramidal configurations. At the same time, Hirshfeld surface analyses showed there are short-range interaction features from the ligand to complexes 1 and 2, the O···H/H···O interactions of the ligand are significantly stronger than those of 1 and 2. [ABSTRACT FROM AUTHOR]

A relatively rigid acyclic salamo-type ligand H2L and its square planar Cu(II) complex, [Cu(L)]·CH3OH, were synthesized and characterized by X-ray crystallography, as well as Fourier-transform infrared spectra, UV–Vis spectra, Hirshfeld surface analyses and DFT calculations. The ligand crystallizes in monoclinic space group P 21/c and has pairs of intramolecular hydrogen bonds between the oxime nitrogen atoms and the hydroxyl groups. The Cu(II) complex crystallizes in the monoclinic space group P 21/c. The Cu(II) ion is located in the N2O2 cavity of the fully deprotonated salamo-type ligand (L)2− unit, thus forming a four-coordinate distorted square planar geometry. At the same time, a belt-like, 2-D supramolecular structure is formed by the interaction of intermolecular hydrogen bonds, and the intermolecular interaction force is quantitatively analyzed by Hirshfeld surfaces. Significantly, fluorescence properties of the ligand and its Cu(II) complex were also studied. The coordination ratio of the Cu(II) complex was proved by UV–Vis and fluorescence titration experiments. [ABSTRACT FROM AUTHOR]

Two helical centrosymmetric homotetranuclear Cu (II) complexes, [Cu4(L)2(EtOH)2](ClO4)2·2EtOH·2CHCl3(1) and [{Cu4(L)2(EtOH)2}{Cu4(L)2(HNO3)2}](NO3)4·3EtOH·3MeOH (2), were synthesized by the reactions of a symmetric bis (salamo)‐based ligand H3L with Cu(ClO)2·6H2O and Cu(NO)3·3H2O, respectively, and certified by elemental analyses, UV–Visible absorption spectra, infrared spectra and single‐crystal X‐ray analysis techniques. X‐ray crystal structure analyses reveal that four Cu (II) atoms of complex 1 are attached to two deprotonated ligand (L)3− units with the help of two coordinated ethanol molecules, and then forming a helical centrosymmetric complex by H‐bonding and π⋯π interactions. While complex 2 unit cell contains two crystallographically independent but chemically identical homotetranuclear complexes (molecules A and B), eight Cu (II) atoms are coordinated by four deprotonated ligand (L)3− units. The coordination mode of four Cu (II) atoms from molecule A is the same as complex 1; at the same time, oxygen atoms on nitrates are involved in the coordination of another four Cu (II) atoms from molecule B. The short‐range interactions in complexes 1 and 2 were calculated by Hirshfeld surfaces analyses. The molecular orbital energy levels, molecular stabilities of complexes 1 and 2 were analyzed by DFT calculations. In addition, antibacterial assays were also investigated in detail. [ABSTRACT FROM AUTHOR]

d-Block transition metal(II)-lanthanide(III) (3d-4f) hetero‐trinuclear [Cu(II)2Ln(III)] (Ln = La and Ce) complexes [Cu2La(L)(ƞ2-NO3)3(CH3OH)2]·2CH3OH (1) and [Cu2Ce(L)(ƞ2-NO3)3(CH3OH)2]·2CH3OH (2) are described, both of which are formed by a flexible symmetrical bis(salamo)-type ligand H4L. The two 3d-4f complexes have been synthesized and characterized by elemental analyses, IR spectra and UV–Vis spectroscopy. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction analyses. In 1 and 2, each Cu(II) ion (Cu1 or Cu2) is located in the N2O2 cavity of an (L)4− unit, while the apex is occupied by one oxygen atom of the coordinated methanol molecule, forming a penta-coordinated square pyramidal geometry. The lanthanide(III) (La or Ce) ion is located in the O6-donor coordination sphere of the completely deprotonated (L)4− unit and coordinated with the other six oxygen atoms of the three nitrate ligands to form a twelve-coordinated icosahedron. At the same time, the supramolecular structures are formed by intermolecular hydrogen bonding interactions and quantitatively determined by Hirshfeld surfaces analyses. Fluorescence properties and DFT calculations of 1 and 2 were also studied. [ABSTRACT FROM AUTHOR]

Two novel homomultinuclear complexes [Co6(L)2(μ‐OAc)4]·2CHCl3·CH3COCH3 (1) and [Ni2(L)(H2O)2(Py)2]·2CHCl3 (2) with a newly designed rigid bis(salamo)‐type tetraoxime ligand (H4L) were synthesized and characterized by elemental analyses, Fourier transform infrared (FT‐IR) spectra, UV–Vis absorption spectra, and X‐ray single‐crystal diffractions. Complex 1 is a novel triple‐decker symmetrical six‐core cluster structure with twofold axis and inversion center. The Co(II) atoms were sandwiched between the bis(salamo)‐type ligands and possess two different geometries of distorted tetragonal pyramid and octahedron, respectively. Complex 2 possesses a dinuclear structure and the Ni(II) atoms are located in the N2O2 cavities of the ligand, and axial coordination atoms come from the coordinated water and pyridine molecules. Both Ni(II) atoms adopt distorted octahedral geometries. The interactions were quantitatively determined by Hirshfeld surfaces analyses of complexes 1 and 2. The coordination ratios were determined by studying the fluorescence properties of complexes 1 and 2. The results of fluorescence titration experiment show that the metals to ligand binding ratios are 6:2 and 2:1 for complexes 1 and 2, respectively. [ABSTRACT FROM AUTHOR]

Two dinuclear Ni (II) and Zn (II) salamo‐type complexes, [Ni2(L)(μ‐OAc)(MeOH)]·2CHCl3 (1) and [{Zn2(L)(μ‐OMe)}3]·3CHCl3·MeOH (2), have been successfully synthesized by wet‐chemical method and characterized by elemental analyses, IR spectra, UV–Vis spectra and single crystal X‐ray diffraction. Complex 1 consists of two closely related dinuclear units 1A and 1B, and complex 2 consists of three closely related dinuclear units 2A, 2B and 2C. The five units are unique example of crystallographically independent but chemically identical molecules. The Ni (II) atoms of complex 1 are located in the N2O4 coordination cavities, possessing six‐coordinated distorted octahedral geometries, but all Zn (II) atoms in complex 2 are located in the N2O3 coordination cavities, possessing five‐coordinated distorted square‐pyramid and triangular bipyramid geometries, the geometries about the Zn (II) atoms (Zn3 and Zn6) that obtain in 2B and 2C where τ5 is very close to 0.500, which is τ5Zn3 = 0.5006 and τ5Zn6 = 0.4941, respectively. The interactions were quantitatively determined by Hirshfeld surfaces analyses. Significantly, fluorescence properties were also investigated. [ABSTRACT FROM AUTHOR]

A new salamo-type bisoxime compound H3L has been synthesized and exploited as a highly efficient chemosensor with multiple responses to Cu2+ and S2−. Chemosensor H3L exhibits highly selective and sensitive detection of Cu2+ and S2− simultaneously. The LODs of Cu2+ and S2− were calculated to be 1.5398 × 10−7 and 1.7274 × 10−7 M in DMF-water (9 : 1, v/v) solution, respectively. The color of the chemosensor H3L solution changed from light green to dark green after adding S2− under a 365 nm UV-lamp. The sensing mechanism of the chemosensor H3L was characterized using several methods, including ultraviolet spectroscopy, ESI-mass spectrometry, 1H-NMR and FT-IR spectroscopy. Meanwhile, the crystal structure of the Cu(II) complex, [Cu2(L)]ClO4·2CH3OH, has been determined by X-ray crystallographic analysis. Density Functional Theory (DFT) was employed to further understand the obtained experimental results. [ABSTRACT FROM AUTHOR]

A new salamo-based ligand and its two new dinuclear complexes [{Co(L)}2(4,4′-bipy)] (1) and [{Cu(L)}2] (2), were designed and self-assembled, and characterized by elemental analyses, FT-IR, UV–vis absorption spectroscopy and X-ray crystallography. In 1, two [Co(L)] units are bridged by the auxiliary bidentate ligand 4,4′-bipy with nitrogen-donor atoms to form a centrosymmetric dimeric structure. Both Co(II) ions are five-coordinate and possess distorted trigonal bipyramidal configurations. Complex 2 is composed of two Cu(II) ions and two completely deprotonated ligand (L)2– units. Interestingly, the two [Cu(L)] units form a dimer bridged by two oxime O atoms. This structure is rare in reported salamo-based Cu(II) complexes. Both Cu(II) ions are five-coordinate and possess distorted tetragonal pyramidal geometries. Hirshfeld surface analyses showed that the O–H/H–O interactions of 1 and 2 are weaker than that of H2L. This phenomenon indicates that H2L forms corresponding complexes with the Co(II) and Cu(II) ions through the deprotonation of phenolic hydroxyl groups. The fluorescence spectra showed that the fluorescence of the ligand is almost completely quenched due to the coordination of the Cu(II) ions with H2L. DFT calculations show that 1 and 2 have higher chemical stability than that of H2L. [ABSTRACT FROM AUTHOR]

Two newly designed heteromultinuclear [CuII4SmIII2] and [CuII2TbIII] bis (salamo)‐based complexes, [{Cu2(L)Sm (NO3)2(μ2‐NO3)(CH3OH)}2]·2CH3OH and [Cu2(L)Tb (NO3)2(μ2‐NO3)][Cu2(L)Tb (NO3)2(μ2‐NO3)(H2O)]·CH3OH, were synthesized and characterized by elemental analyses, Fourier transform infrared (FT‐IR) spectra, ultraviolet–visible (UV–vis) absorption spectra, and X‐ray crystallography. The ultraviolet titration experiments exhibited that the coordination ratio of the ligand, rare earth metal, and transition metal is 1:1:2. In the [CuII4SmIII2] complex, Cu1 atom has a distorted quadrilateral pyramid geometry, whereas Cu2 atom forms a slightly distorted octahedral geometry. The [CuII2TbIII] complex unit cell contains two crystallographically independent and chemically different heterotrinuclear complexes (Molecules A and B). In Molecule A, the Cu1 atom bears a four‐coordinated plane quadrilateral geometry, whereas the five‐coordinated Cu2 atom forms a slightly distorted tetragonal cone geometry. In Molecule B, the five‐coordinated Cu3 and Cu4 atoms possess slightly distorted tetragonal cone geometries. Noncovalent interactions like hydrogen bonding and π···π stacking interactions are operative in construction of supramolecular architectures. The [CuII2TbIII] complex behaves as a catalyst towards oxidative coupling of 2‐AP in MeCN medium. In addition, fluorescence properties of the ligand H4L and its [CuII4SmIII2] and [CuII2TbIII] complexes have also been discussed. [ABSTRACT FROM AUTHOR]

• A salamo-type probe l-Cu2+ containing 1,8-naphthalimide fluorophore was synthesized firstly. • The probe l-Cu2+ can specifically detect S2- further validated through ESP analysis. • Good results in test strip, actual water samples and antibacterial activity were achieved. A novel salamo-based fluorescent chemical sensor l-Cu2+ was designed and prepared via the reaction of H 2 L and Cu(OAc) 2 ·H 2 O. The whole research has found that Cu(II) atom in the complex crystal are located in the N 2 O 2 cavity of H 2 L, forming a four-coordination system. Hirshfeld surface analysis confirmed the presence of hydrogen bonding and π···π stacking interactions. As a probe molecule, l-Cu2+ can selectively and sensitively detect S2- without interference from other ions, and can be effectively used within the biological pH range. In addition, DFT theoretical calculations and molecular electrostatic potential analysis (ESP) were used to investigate the electron cloud density and positive and negative electrostatic potentials inside the probe, as well as the mechanism for identifying sulfur ions. Finally, the probe l-Cu2+ has shown good practical application effects and can recognize S2− in three different water samples. It can also be used as a qualitative detection strip. l-Cu2+ complex possesses excellent application prospect in bacteriostasis. [Display omitted] [ABSTRACT FROM AUTHOR]

Non-stoichiometric Ba (Co 1 / 3 Nb 2 / 3) O 3 (BCN) ceramics were synthesized using the solid-state method at 1150 ℃. The heat treatment process was then followed by sintering at 1400–1550 ℃ and annealing at 1300 °C. Systematically varying the extent of the non-stoichiometry and the heat treatment conditions resulted in the division of the BaO − CoO − Nb 2 O 5 system into two categories of compounds: (A) high-order Co / Ba -deficient and Co / Nb -excess ceramics and (B) completely disordered Nb -deficient and Ba -excess ceramics. It was found that a slight deviation from stoichiometry toward the group (A) and subsequent annealing led to a significant improvement in the ordering from 82% to 100% accompanied with the formation of non-equidistant Nb − O bonds. The crystal structure based on the ultra-high order BCN − 0.02 Ba 5 Nb 4 O 15 was also designed to display non-equidistant Nb − O bonds. The dielectric characteristics demonstrated that high Q correlates with the 1:2 ordering and the highest Q × f values obtained from BCN − x Ba 5 Nb 4 O 15 ceramics (x = 0.02, 0.04, 0.06): 83, 84.95, and 79.71 THz, respectively. [ABSTRACT FROM AUTHOR]

• A nonsymmetric salamo-type ligand H 2 L with both N 2 O 2 and O 3 cavities was constructed. • The presence of different counter-anions affects the configuration of the complexes. • Two Cu(II) complexes synthesized were characterized by ESP, IRI and DFT calculation. A nonsymmetric salamo-type ligand H 2 L with both N 2 O 2 and O 3 cavities was designed and constructed, and single crystals of two copper(II) complexes with completely different structures were grown by coordinating H 2 L with different copper(II) salts, which were determined as [Cu(L)(H 2 O)] (1) and [{Cu 2 (L)(NO 3)(H 2 O) 3 } 2 (μ 2 -NO 3)]NO 3 ⋅EtOH (2). In complex 1 , penta-coordinated copper(II) atom forms a square pyramidal geometry. However, in complex 2 , four copper(II) atoms are all six-coordinated, and form distorted octahedral geometrical configurations. Interestingly, the presence of the counter-anion (NO 3 −) makes a big difference in the configuration of the complexes. Finally, complexes 1 and 2 with a tetragonal cone configuration in mononuclear five-coordinated and an octahedral structure in tetranuclear six-coordinated were formed, respectively. In addition, theoretical calculations were performed, such as IRI valuations, Hirshfeld surfaces analyses, DFT and ESP. Calculations have further demonstrated the existence of different weak interactions and electronic nature between the ligand and its complexes thus indirectly proving the reason why the complexes are more stable than ligand. [Display omitted] [ABSTRACT FROM AUTHOR]

• A quinoline-including half-salamo like N 3 O-donor ligand was synthesized. • Differently structural Cu(II) and Ni(II) complexes were synthesized and structurally characterized. • The intermolecular interactions were quantitatively analyzed by hirshfeld surfaces and 2D fingerprint plots. A half-salamo like N 3 O-donor ligand HL was synthesized and used for the construction of Cu(II) and Ni(II) complexes, namely as [Cu(L)(NO 3)] (1) & [Ni 2 (L) 2 (NO 3) 2 ]·2H 2 O (2). The constructed complexes were structurally characterized by X‐ray crystallography technique. The results revealed that the complex 1 is the most common mononuclear species, in which Cu(II) ion is penta-coordinate with twisted square pyramid configuration. Unlike complex 1, the central Ni(II) ions of dinuclear complex 2 are hexa-coordinate possessing slightly distorted octahedron. The final supramolecular structures of the two complexes are stabilized and expanded by noncovalent interactions. In addition, spectral characteristics of the title complexes were examined. The frontier molecular orbitals as well as energy gaps of the complexes were explored by density functional theory calculation. The primary aspects of the ultraviolet absorption spectra were interpreted using time-dependent density functional theory computation. Thorough analysis of the Hirshfeld surfaces quantifies the interactions involved in the crystal structures of the Cu(II) and Ni(II) complexes. Two differently structural metal(II) complexes [Cu(L)(NO 3)] (1) and [Ni 2 (L) 2 (NO 3) 2 ]·2H 2 O (2) containing a half-salamo like N 3 O-donor ligand were successfully synthesized and characterized. The spectral properties of the two complexes were studied. Moreover, the frontier molecular orbitals as well as energy gaps of the complexes were explored by DFT calculation. The Hirshfeld surfaces analyses and 2D fingerprint plots were performed to quantify the interactions involved in the crystal structures of the two complexes. [Display omitted] [ABSTRACT FROM AUTHOR]

• A quinoline-appended acylhydrazone H 2 L was designed and prepared. • The Zn(II) acylhydrazone complex [Zn(HL) 2 ]·H 2 O was prepared and elucidated tructurally. • The ligand HL and its Zn(II) complex showed unique luminescent mechanochromism. • The self-assembly process and weak intermolecular forces of complexes were explained. In the work, a quinoline-appended acylhydrazone H 2 L was designed and prepared via a Schiff base condensation reaction of quinoline-2-formaldehyde and salicylhydrazide. Further, a new zinc(II) complex, [Zn(HL) 2 ]·H 2 O was synthesized by the reacting of the ligand H 2 L and Zn(NO 3) 2 ·6H 2 O in dichloromethane/ethanol solution. The ligand and its Zn(II) complex were elucidated via UV–Vis, FT-IR, DFT calculation, Hirshfeld surfaces, MEP & IRI analyses, and X-ray single-crystal diffractions. The results of Hershfield surface analysis showed that there are obvious hydrogen bond interactions and C H···π mutual effect in the Zn(II) complex. In addition, solid-state photoluminescence properties indicated that H 2 L and its Zn(II) complex represent uncommon luminescent mechanochromism tuned via intermolecular hydrogen bonds. A quinoline-appended acylhydrazone ligand H 2 L and its Zn(II) complex [Zn(HL) 2 ]·H 2 O, were prepared and elucidated structurally. The results of Hershfield surface analysis showed that there are obvious hydrogen bond interactions and C H···π mutual effect in the Zn(II) complex. In addition, solid-state photoluminescence properties indicated that H 2 L and its Zn(II) complex represent uncommon luminescent mechanochromism tuned via intermolecular hydrogen bonds. [Display omitted] [ABSTRACT FROM AUTHOR]

A new salamo-type bisoxime compound H3L has been synthesized and exploited as a highly efficient chemosensor with multiple responses to Cu2+ and S2−. Chemosensor H3L exhibits highly selective and sensitive detection of Cu2+ and S2− simultaneously. The LODs of Cu2+ and S2− were calculated to be 1.5398 × 10−7 and 1.7274 × 10−7 M in DMF-water (9 : 1, v/v) solution, respectively. The color of the chemosensor H3L solution changed from light green to dark green after adding S2− under a 365 nm UV-lamp. The sensing mechanism of the chemosensor H3L was characterized using several methods, including ultraviolet spectroscopy, ESI-mass spectrometry, 1H-NMR and FT-IR spectroscopy. Meanwhile, the crystal structure of the Cu(II) complex, [Cu2(L)]ClO4·2CH3OH, has been determined by X-ray crystallographic analysis. Density Functional Theory (DFT) was employed to further understand the obtained experimental results. [ABSTRACT FROM AUTHOR]

• A novel Salamo-Salen-Salamo hybrid ligand H 4 L was explored. • Mononuclear Salamo-Salen-Salamo-Ni(II) complex has been synthesized and characterized structurally. • A series of theoretical calculations of the Ni(II) complex were performed. The Salen compound is a typical Schiff base ligand, and by combining one Salen-structure unit with two Salamo-structure units, a novel hybrid Salamo-Salen-Salamo-type ligand H 4 L was synthesized. The synthesis of corresponding complexes based on the hybrid ligand was studied. Ni(II) ion participates in coordination and synthesizes a hybrid Salamo-Salen-Salamo-type mononuclear complex [Ni(LH 2)]. X-ray single crystal diffraction analysis showed that Ni(II) ion has coordinated with Salen N 2 O 2 structure, forming a planar geometry with tetracoordination. The Salamo structure units are not involved in coordination, and two Salamo long chains are spatially close to each other and there are N, O atoms that are easy to coordinate with metals, forming a potential coordination environment. The spectral properties of the complex was further discussed by IR and UV-vis spectroscopy, and the binding ratio of the ligand H 4 L to Ni(II) ion in solution was verified by UV-vis titration spectroscopy. Through the structural optimization of the ligand and single-point energy calculation of the complex, the HOMO-LUMO gaps of the ligand and the complex were analyzed to determine the softness of the ligand and the complex. TD-DFT analysis of the ligand and its complex was found to be consistent with experimental results, and the energy level transition sources of the main absorption peaks and their contributions were analyzed. The interaction force within the molecule of the Ni(II) complex was calculated, and finally the movable free region of the complex molecule in the unit cell was calculated and displayed. A hybrid ligand containing both Salamo and Salen structures was synthesized in a multi-step reaction. Based on the hybrid Salamo-Salen-Salamo-type ligand H 4 L, a mononuclear Ni(II) complex was synthesized and characterized by IR and UV-Vis spectroscopy, and the ratio of Ni(II) ion to H 4 L was demonstrated through UV-Vis titration spectroscopy. Theoretical UV-Vis spectra of H 4 L and its Ni(II) complex, HOMO-LUMO gaps and weak intramolecular interactions were studied through computational chemistry. [Display omitted] [ABSTRACT FROM AUTHOR]

• Two structurally different Co(II) Salamo-type complexes were synthesized and characterized structurally. • The varying degrees of distortion of the ligand have an undeniable impact on the formation of the two Co(II) complexes. • H 2 L and its Co(II) complexes were characterized by BVS, IRI and DFT calculation. A new non-symmetric salamo-type multidentate chelating ligand H 2 L (4-Formyl-6ʹ-methoxyl-2,2ʹ-[ ethylenedioxybis (nitrilomethylidyne)]diphenol) was designed and prepared. Two Co(II) complexes with different structures, [Co(L)(H 2 O)] (1) and [Co 2 (L) 2 ] 2 ·3CH 3 CN·2CH 3 OH (2) were prepared by the reactions of H 2 L with two different Co(II) salts (Co(OAc) 2 ·4H 2 O/CoCl 2 ·6H 2 O) in various organic solvents at an ambient temperature, respectively. Due to varying degrees of distortion of the ligand during the coordination reactions, the bonding modes of the ligand in complexes 1 and 2 are different. Complex 1 forms a penta-coordinated mononuclear, and complex 2 forms a penta-coordinated binuclear structure. By comparing UV–Vis and infrared spectroscopy of H 2 L with those of the corresponding complexes further characterize coordination between the ligand H 2 L and Co(II) ions. Theoretical calculations of DFT, BVS (Valence Bonding and Calculation), and IRI (Interaction Region Indicator) were used to show the different forces present in complexes 1 and 2 , and BVS calculations confirmed that Co is '+2′ valence in the complexes. Fluorescence property studies indicated that the possible mechanism for the decrease in fluorescence intensity upon binding of H 2 L to Co(II) ions is chelation fluorescence quenching. Based on a new non-symmetric Salamo-type ligand H 2 L, two penta-coordinated Co(II) complexes with different structures were synthesized and characterized structurally. Due to varying degrees of distortion of the ligand during the coordination reactions, the coordination modes of the ligand in the two complexes are different. Complex 2 contains two crystallographically independent but chemically identical molecules (molecules A and B). All the five Co(II) atoms possess distorted trigonal bipyramidal geometries. [Display omitted] [ABSTRACT FROM AUTHOR]

• Binuclear and novel tetranuclear Cu(II) were synthesized and characterized. • The geometries of Cu(II) atoms in complexes 1 and 2 are distinctly different. • The 3-hydroxy coordination easily forms a polynuclear complex. • Different counterions and solvents can give rise to various complexes. • Complexes 1 and 2 show some degree of fluorescence quenching. In this work, a linear acyclic oligo(N,O-donor) salamo-based chelate ligand H 4 L containing both dioxime and Schiff base functionalities was synthesized. Its various bi-nuclear and tetra-nuclear complexes, [Cu 2 (HL)(μ -OAc)]·CH 3 OH (1) and [Cu 4 (HL) 2 (EtOH)](ClO 4) 2 ·2EtOH (2) were self-assembled via the ligand H 4 L with stoichiometric quantities of Cu(OAc) 2 ·H 2 O/Cu(ClO 4) 2 ·6H 2 O in methanol/ethanol, respectively. The bi-nuclear complex 1 consists of a partly deprotonated (HL)3− anion, two Cu(II) atoms, one μ -OAc− counterion. Each Cu(II) atom center is surrounded by a tetragonal cone geometry. However, complex 2 containing four Cu(II) ions, two partially deprotonated (HL)3− anions, and a ligated ethanol molecule, which forms tetranuclear complex 2 containing four and five-coordinated geometries. The structure of complex 2 acquired is unique as shown herein, the different nucleation numbers and geometrical configurations of the resulting crystal structures may be due to the different anions and solvents used in the synthesis process. The binding ratios of the oligo(N,O-donor) ligand to Cu(II) ions were confirmed by UV titration experiments, two of which are consistented with the single-crystal structures. Finally, MEPs, IRI, Hirshfeld surfaces, and intermolecular interactions and reactive sites were analyzed further, the fluorescent properties were explored. Bi- and tetra-nuclear Cu(II) salamo-based complexes, [Cu 2 (HL)(μ -OAc)]·CH 3 OH (1) and [Cu 4 (HL) 2 (EtOH)](ClO 4) 2 ·2EtOH (2) were synthesized and structurally characterized. Complexes 1 and 2 possess four- and five-coordinated geometries, The intermolecular interactions of Cu(II) complexes 1 and 2 were elucidated, which are consistent with the crystal structures. The fluorescence properties of H 4 L and its Cu(II) complexes were investigated. [Display omitted] [ABSTRACT FROM AUTHOR]

• A double-armed salamo-like ligand was developed. • The crystal structure of the first double-armed salamo-like M(II) complex was reported. • The presence of two bridged acetate groups plays a crucial role in the stability of the complex. • Fluorescence properties and theoretical calculations were investigated. The first double-armed salamo-based tri-nuclear Ni(II) complex, named as [Ni 3 (L)(μ 2 -OAc) 2 ]·3CHCl 3 was successfully self-assembled, and elucidated via elemental analyses, spectroscopic technology and theoretical analyses. The results indicated that one ligand H 4 L has coordinated with three Ni(II) atoms in a 1:3 ratio unreported previously. One of the three Ni(II) atoms is located at the cavity of the N 2 O 2 donor, while other two Ni(II) atoms are sited at the NO 2 cavities formed by double-armed salicylaldehyde moieties, respectively, and further coordinated via two bridging μ 2 -acetate groups, which is a quite novel structure. The fluorescent properties and a range of theory calculations in the ligand and its Ni(II) complex were researched in detail. A novel double-armed salamo-like tri-nuclear Ni(II) complex, [Ni 3 (L)(μ-OAc) 2 ]·3CHCl 3 was successfully self-assembled for the first time. X-ray single-crystal diffraction results showed that the Ni(II) complex is formed by a 1:3 coordination ratio between H 4 L and three Ni(II) atoms and presents a novel structure. Besides, infrared spectroscopy, UV-vis spectroscopy, a series of theoretical calculations and fluorescence properties of H 4 L and its Ni(II) complex were studied. [Display omitted] [ABSTRACT FROM AUTHOR]

• The quinoline-decorated N 3 O-donor half-salamo type ligand HL was designed and synthesized. • Two novel Co(Ⅱ) complexes [Co(L)Cl] (1) and [Co(L)(NCS)] (2) were obtained by the reaction of HL with different Co(Ⅱ) salts. • Quantitative analyses of intermolecular interactions in the crystalline structures were performed by Hirshfeld surfaces analysis. Self-assembly through a quinoline-decorated N 3 O donor half-salamo-type tetradentate ligand HL and coordinative preference of Co(II) ion, two novel Co(II) complexes [Co(L)Cl] (1) and [Co(L)(NCS)] (2) were synthesized and characterized. X-ray crystallography revealed that both complexes 1 and 2 have similar mononuclear structure, in which the five-coordinated Co(II) atoms are not only surrounded by the N 3 O cavity of the deprotonated ligand (L)− unit, but also coordinated with different Cl− and NCS− anions. For the involvement of different anions, the crystal structures of the two complexes exhibit intermolecular C H···Cl and C H···S hydrogen interactions in building supramolecular assemblies, respectively. The two complexes are stabilized by C H···O, C H···N, C H···C, C H···S bonds and C H···π, π···π interactions. The spectral properties of the complexes were investigated through UV–Vis and fluorescence spectroscopy. In addition, the detailed analyses of Hirshfeld surfaces and fingerprint plots provide the basis of the intermolecular interactions in building crystal blocks. Two novel Co(II) complexes, [Co(L)Cl] (1) and [Co(L)(NCS)] (2) with a quinoline-decorated half-salamo type ligand HL were synthesized and characterized structurally. In addition, spectroscopic properties, DFT calculations and Hirshfeld surfaces analyses of HL and its two Co(II) complexes were investigated in detail. [Display omitted] [ABSTRACT FROM AUTHOR]

• An unexpected mono-nuclear Cu(II) complex was successfully prepared. • The complex is formed by the reaction of Cu(II) acetate with H 2 L1, not by the H 3 L. • DFT, ESP and Hirshfeld surfaces analyses of the Cu(II) complex were investigated. An unexpected mono-nuclear Cu(II) complex [Cu(L1)] was successfully prepared by a bis(salamo)-type ligand H 3 L and Cu(OAc) 2 ·H 2 O in ethanol/acetone mixed solvent, and its structure and properties were analyzed. The crystal structure analysis showed that the Cu(II) complex is obtained by the reaction of copper(II) acetate with a new single salamo-type ligand H 2 L1, not obtained from the original ligand H 3 L. The molecular front orbitals HOMO and LUMO of the ligand H 3 L and the Cu(II) complex were analyzed by quantum chemical calculations, and the results showed that the energy gap of the Cu(II) complex is reduced due to the combination of orbitals compared to the ligand. The theoretical reaction sites of the ligand H 3 L with the Cu(II) were analyzed by ESP studies, and the results showed that the crystal structure of the Cu(II) complex is consistent with the theoretical predictions. Hirshfeld surfaces analyses confirmed the rich and diverse interactions present in the Cu(II) complex, which is essential for the stability of the molecules. [Display omitted] The unexpected Cu(II) complex [Cu(L1)] was successfully prepared by a bis(salamo)-type ligand H 3 L, and its structure and properties were analyzed. Unexpectedly, the obtained complex was not formed by the original ligand, but the new ligand formed, H 2 L1, reacted with copper acetate to obtain a mononuclear copper complex due to the catalytic effect of copper acetate on the ligand at N O bond in the oxime group leading to the breakage of the ligand. [ABSTRACT FROM AUTHOR]

• Complexes 1 and 2 were successfully prepared and characterized structurally. • Complex 2 is not obtained from H 3 L but from a new ligand H 2 L1. • Theoretical calculations and fluorescence properties were investigated in detail. Two unusual bis(salamo)-based Co(II) complexes, [Co 2 (L)(OMe)]·2MeOH (1) and [Co 4 (L1) 4 (MeOH) 4 ] (2) were designed and successfully prepared, and characterized structurally. The crystal structure analysis showed that complex 1 is composed of one fully deprotonated ligand (L)3− moity, two divalent Co(II) atoms and one bridge-coordinated methanol molecule, while complex 2 is an asymmetric homotetranuclear structure made up of four Co(II) atoms, four fully deprotonated (L1)2− units and four coordinated methanol molecules. It is noteworthy that the reaction of cobalt(II) nitrate with H 3 L produces complex 2. This complex is not obtained from the original ligand H 3 L but from a new ligand H 2 L1. Therefore, the phenomenon can be used to prepare metal(II/III) complexes with excellent structure. The molecular frontier orbitals HOMO and LUMO of H 3 L and complexes 1 and 2 were analyzed by DFT calculations, and the results showed that the energy gaps of the complexes were reduced due to the combination of the orbitals compared to the ligand. The reaction sites of H 3 L with Co(II) atoms were analyzed by ESP studies, and the results showed that the crystal structures of the complexes are consistent with the theoretical predictions. Hirshfeld surface analyses indicated the different interactions in the complexes, and revealed that the main contributions to the crystal stacking were from H H, C H and H O interactions. The interactions in the complexes were further explored by IRI research, the results exhibited that there are abundant interactions in complexes 1 and 2 , which are important for their construction of supramolecules. The fluorescence strengths of complexes 1 and 2 are significantly lower compared to H 3 L, which can be attributed to the ligand to metal charge transition (LMCT). [ABSTRACT FROM AUTHOR]

• A salamo-like coordination polymer Cd(II)-CP is successfully synthesized through insert auxiliary ligand. • The Cd(II)-CP is bifunctional sensor toward picric acid (PA) and S2−, which exhibit turn-off and turn-on fluorescence effects. • The sensor Cd(II)-CP can be used for the detection of PA and S2− in environmental water samples. A tailored Cd(II) coordination polymer [Cd(HL) 2 (1,4-pbyb)] n (Cd(II)-CP), has been synthesized successfully by using the host ligand H 2 L (4‑chloro-4ʹ‑bromo-6‑bromo-6ʹ‑tert‑butyl‑2,2ʹ-[ ethylenedioxybis (nitrilomethylidyne)]diphenol) and auxiliary ligand 1,4-di(pyridin-4-yl)benzene (1,4-pbyb) under the room temperature volatilization method. Single crystal X-ray diffraction experiment showed that Cd(II) atoms possess a slightly twisted hexa-coordinated octahedron configuration and Cd(II)-CP forms an infinite 1D zigzag-like chain configuration. The structural diversity of Cd(II)-CP is mainly attributed to the introduction of auxiliary ligand. The Cd(II)-CP is a highly selective and sensitive luminescent bifunctional chemosensor toward nitroaromatic compounds (NACs) and anions, which exhibits turn-off fluorescence effect on picric acid (PA) and turn-on fluorescence effect for sulfide ions (S2−). The sensing mechanisms were also carefully investigated. This study provides new conceptions for the design of CPs for detecting pollutants from surroundings, potentially mitigating health risks to humans and natural ecosystems. A customized Cd(II) coordination polymer [Cd(L) 2 (1,4-pbyb)] n (Cd(II)-CP), has been synthesized using the host ligand H 2 L with auxiliary ligand 1,4-pbyb. The Cd(II)-CP is highly selective and sensitive luminescent bifunctional chemosensor toward picric acid (PA) and S2−, which exhibits turn-off fluorescence effect on PA and turn-on fluorescence effect for S2−. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel tetranuclear Cu(II) salamo-like complex has been synthesized and characterized structurally. • Different modes of the Cu(II) complex were obtained by changing the reaction ratio between H4L and copper(II) salts. • The four Cu(II) atoms possess respectively four- and five-coordinated modes. • A series of theoretical calculations and fluorescence properties of H4L and its Cu(Ⅱ) complex were investigated. A novel tetra-nuclear Cu(II) salamo-like complex containing four- and five-coordinated Cu(II) atoms, [Cu 4 (L) 2 (MeOH) 2 ]·2MeOH was synthesized and characterized structurally. The single crystal X-ray diffraction analysis indicated the Cu(II) complex is a triclinic system, including four Cu(II) atoms and two completely deprotonated ligand (L)4− units, forming an asymmetric geometric structure. Specifically, Cu2 and Cu4 atoms are located in the N 2 O 2 cavities of two different ligand (L)4− units, respectively, and coordinate with one methanol molecule in the axial position to form five-coordinated tetragonal pyramid geometries. Meanwhile, Cu1 and Cu3 atoms respectively coordinate with four phenoxy atoms in the two ligand (L)4− units to form slightly distorted planar quadrilateral geometries with four coordination. The spectral properties of the ligand H 4 L and its Cu(II) complex were further analyzed by IR, UV–vis absorption spectra and fluorescence spectra. DFT calculation results showed that the Cu(II) complex has low optical reaction activity. In addition, the electrophilic and nucleophilic sites favorable for the formation of hydrogen bonds were found through molecular electrostatic potential analysis. Hirshfeld surface analysis identified the interactions in the crystal structure. In the Cu(II) complex, H···H/H···H interaction is dominant, indicating that there are a large number of hydrogen bonds in the complex. IRI analysis revealed that there are weak hydrogen bond interactions, all of which make the Cu(II) complex more stable. [ABSTRACT FROM AUTHOR]

• A rigid bis(salamo)-like ligand H 4 L was designed and synthesized successfully. • A structurally novel tetranuclear Ni(II) complex was synthesized and characterized structurally, acetylacetone anions participate in the coordination as auxiliary bidentate ligands. • The Ni(II) complex was analyzed by MEPs and IRI, and the intermolecular interactions were clarified. Novel tetranuclear Ni(II) complex [Ni 4 (L)(acac) 4 (EtOH) 2 ]⋅4CH 2 Cl 2 was synthesized by a rigid bis(salamo)-like ligand H 4 L and Ni(acac) 2 in ethanol/dichloromethane mixed solvents, and characterized by different physicochemical methods. The X-ray diffraction result showed that all Ni(II) atoms are hexa-coordinated with slightly distorted octahedral geometries, and four Ni(II) atoms are correlated with each other through inversion. Acetylacetone anions acted as auxiliary ligands for bidentate chelation, and the monodentate ethanol molecules of solvent participated in the coordination. The properties of the ligand H 4 L and its Ni(II) complex were studied, including molecular electrostatic potential surface (MEPs), Hirshfeld surface and interaction region indicator (IRI) analysis. Through the above study, the reaction active sites were visualized, and the intermolecular interactions of the Ni(II) complex were clarified, which is consistent with the crystal structure of the Ni(II) complex. In addition, fluorescence spectra of the ligand H 4 L and its Ni(II) complex were investigated. Novel tetranuclear Ni(II) bis(salamo)-like complex [Ni 4 (L)(acac) 4 (EtOH) 2 ]⋅4CH 2 Cl 2 was synthesized and characterized structurally. All the Ni(II) atoms are hexa-coordinated with slightly distorted octahedral geometries, acetylacetone anions as auxiliary bidentate ligands participate in chelation. The reaction active sites were visualized, and the intermolecular interactions of the Ni(II) complex were clarified, which is consistent with the crystal structure of the Ni(II) complex. Fluorescence properties of H 4 L and its Ni(II) complex were investigated. [Display omitted] [ABSTRACT FROM AUTHOR]

• Poly-nuclear Zn(II) and Ni(II) salamo-type complexes were synthesized and characterized structurally. • The decoordination sites of the aldol condensation reaction leads to the occurrence of self-assembly. • Fluorescence properties and theoretical calculations of complexes 1 and 2 were explored. Based on a salamo-type ligand H 2 L containing a bare formyl group, a di-nuclear salamo-Zn(II) complex [Zn 2 (L)Cl 2 ] (1) was synthesized. With the occurrence of Claisen-Schmidt reaction catalyzed by triethylamine, the O 4 coordination environment of the H 2 L ligand is destroyed, producing a new ligand H 2 L′. Which conflicts with the characteristics of Ni(II) atoms that are generally multi-coordinate, driving the occurrence of self-assembly reaction, and obtaining a tetra-nuclear salamo-Ni(II) complex [Ni 4 (L′) 2 (µ 2 -Cl) 2 (µ 3 -OMe) 2 (EtOH) 2 ] (2). X-single crystal diffraction analyses showed that two Zn(II) atoms in the salamo-Zn(II) complex occupy the cavities of N 2 O 2 and O 4 , respectively, while Ni1 and Ni1# atoms in the salamo-Ni(II) complex occupy the N 2 O 2 cavities from two H 2 L′ ligands, there are many bridges (µ 2 -Cl− & µ 3 -OMe− aions) between Ni2 and Ni2# atoms. The UV–Vis titration experiments demonstrated the binding ratio of H 2 L to Zn(II) atoms is 1:2, while the binding ratio of the ligand H 2 L′ to Ni(II) atoms is also 1:2, the results are consistent with the X-ray single crystal structures. Through DFT calculation, the single-point energy of complexes 1 and 2 and the optimized structure of the ligand H 2 L were found that the softness of HOMO-LUMO gap of salamo-Zn(II) complex is small and not easy to deform, and the softness of salamo-Ni(II) complex is large and easy to deform, which is in agreement with the calculated results of intra-molecular interactions in IRI. The interaction of a large number of hydrogen bonds, C-H...π, π...π, van der Waals forces and so on in salamo-Ni(II) complex makes it easy to deform. The fluorescence properties of H 2 L and the salamo-Zn(II) complex have also been studied. Based on a salamo-type ligand H 2 L containing a bare formyl group, a di-nuclear salamo-Zn(II) complex [Zn 2 (L)Cl 2 ] (1) was synthesized. With the occurrence of the Claisen-Schmidt reaction catalyzed by triethylamine, the O 4 environment of the H 2 L ligand is destroyed, producing a new ligand H 2 L'. Which conflicts with the characteristics of Ni(II) atoms that are generally multi-coordinate, driving the occurrence of self-assembly reaction, and obtaining a tetra-nuclear salamo-Ni (II) complex [Ni 4 (L') 2 (µ 2 -Cl) 2 (µ 3 -OMe) 2 (EtOH) 2 ] (2). Fluorescence properties and a range of theoretical calculations complexes 1 and 2 were investigated in detail. [Display omitted] [ABSTRACT FROM AUTHOR]

• The first salamo-type mixed-ligand metal(II) polymer was synthesized and characterized structurally. • The interaction forces existing within the polymer molecules were investigated by relevant theoretical calculations. • The antimicrobial activities of the two ligands and their polymer were investigated. In this work, a copper(II) coordination polymer [Cu 2 (L1)(L2)(NO 3)] n ·nCH 3 OH (Cu(II)-CP) with different structures of mixed salamo-type ligands was constructed for the first time. Single crystal X-ray diffraction analysis showed that the Cu(II)-CP asymmetric unit consists of two copper(II) atoms, fully deprotonated (L1)−, (L2)2− ligand units, one NO 3 − anion and one molecule of crystallized methanol. The two metallized ligand units are bridged by two oxygen atoms of NO 3 − to form unique mixed-ligand copper(II) coordination polymer. In addition, the six coordination atoms around the two Cu(II) atoms are all arranged in a distorted octahedral geometry. In the molecular structure of Cu(II)-CP , neighbouring molecules interact through intermolecular hydrogen bonds to form a two-dimensional supramolecular structure. Intermolecular interactions and molecular stability were further investigated by Hirshfeld surface analysis and other theoretical calculations. Finally, the antimicrobial activities of both ligands and Cu(II)-CP were investigated and found to exhibit excellent antibacterial activities. [Display omitted] A Cu(II) coordination polymer [Cu 2 (L1)(L2)(NO 3)] n ·nCH 3 OH with salamo-type mixed ligands was synthesized for the first time. The structure of the polymer was characterized and the intramolecular forces were studied through theoretical calculations. In addition, the antimicrobial activities of the two ligands and their polymer were investigated. [ABSTRACT FROM AUTHOR]

MAPbBr 3 single crystals have attracted much attention because of their high quantum efficiency and photoluminescence (PL) peaks. It has been researched that the crystal has two PL peaks and the additional PL peak comes from the "PbBr 2 " defect in the crystal. This can be well applied to dual-wavelength lasers. However, the change rule of the PL two peaks intensity is not clear. Herein. Crystals with two PL peaks are obtained by inverse temperature crystallization. We research the crystal structures of MABr and PbBr 2 in different proportions, and find that these crystals have varying degrees of defects. Moreover, we confirm that these defects are Schottky defects based on experimental and simulated XRD. The optical properties of the samples are studied, which suggest that the PL intensity is related to the ratio of MABr to PbBr 2. The energy level distribution of the crystal is calculated by energy level simulation, which further explains that the 536 nm is generated by "PbBr 2 " and the 567 nm is generated by MAPbBr 3. All the results illustrate that the intensity of two peaks can be adjusted by the ratio of MABr to PbBr 2. The maximum intensity is at 536 nm for MABr: PbBr 2 = 2 and 567 nm for MABr: PbBr 2 = 0.5. We explain this change rule of two peaks intensities from the energy level point of view and obtained MAPbBr 3 crystals with high PL intensity corresponding to different wavelengths. This research provides a theoretical basis for the change in PL bimodal intensity, and an experimental reference for perovskite dual-wavelength laser. • The change of photoluminescence two pesks intensity of MAPbBr 3 is related to the content of MABr，which is proposed and illustrated. • The types of crystal defects caused by the MABr content were determined, and the crystal surface structure models of different ratio of MABr to PbBr 2 were established, based on the experimental and simulated XRD. • The energy level simulation is quite consistent with the experimental results. • The model of dual-wavelength perovskite laser is proposed. [ABSTRACT FROM AUTHOR]

• Heterobimetalic [Cu(II)2Ln(III)] (Ln = La and Ce) complexes were synthesized and characterized structurally. • It can be seen from complex 2 that the coordination ability of nitrate is stronger than that of acetic acid. • Hirshfeld surface analyses, DFT calculations and luminescences of the complexes 1 and 2 were investigated. Two heterobimetallic [Cu(II) 2 Ln(III)] (Ln = La and Ce) complexes composed of flexible bis(salamo)‐type ligand H 4 L with Cu(II) and Ln(III) atoms, [Cu 2 La(L)(ƞ 2-NO 3) 3 ]·EtOH (1) and [Cu 2 Ce(L)(ƞ 2-NO 3) 3 ]·EtOH (2) have been successfully synthesized, and characterized by IR spectra, elemental analyses, UV–Vis spectroscopy, the crystal structures of the complexes 1 and 2 were determined by single-crystal X-ray diffraction analyses. Each Cu(II) atom of the complexes 1 and 2 is located in the N 2 O 2 -donor of the completely deprotonated (L)4− unit, so that the two Cu(II) atoms have tetra-coordinated slightly distorted square planar geometries, while the Ln(III) (La or Ce) atom is located in the O 5 cavity of the ligand (L)4− unit. At the same time, there are six oxygen atoms from three bidentate nitrate groups coordinated with the Ln(III) (La or Ce) atom, resulting in the formation of an eleven-coordinated augmented sphenocorona J87. In addition, DFT calculations and Hirshfeld surfaces analyses are performed and fluorescence properties are evaluated. [Display omitted] Two heterobimetalic [Cu(II)2Ln(III)] (Ln = La and Ce) complexes composed of a flexible bis(salamo)‐type ligand H4L with Cu(II) and lanthanide(III) atoms, [Cu 2 La(L)(ƞ2-NO 3) 3 ]·EtOH (1) and [Cu 2 Ce(L)(ƞ2-NO 3) 3 ]·EtOH (2) have been successfully synthesized. The central lanthanide(III) atom forms eleven-coordinated augmented sphenocorona J87. At the same time, DFT calculations are performed and fluorescence properties are evaluated. [ABSTRACT FROM AUTHOR]

[Display omitted] • An aldehyde-appended salamo-like ligand H 2 L has been developed. • Counterions play a non-negligible role in the construction of dimeric Cu(II) complexes. • Two novel homopolynuclear Cu(II) complexes were characterized structurally. A N 2 O 3 -donor aldehyde-appended salamo-like ligand H 2 L has been designed and synthesized successfully, and can be used to prepare [{Cu(L)} 2 ] (1) and [Cu 3 (L) 2 (EtOH) 2 ]·2ClO 4 (2) with different nuclearity and extraordinary structures by changing the reaction conditions (various counter-anions and solvent molecules). In addition, the structures of two complexes were determined by single-crystal X-ray diffraction experiments. The results showed that complex 1 is a novel (L)2−: Cu(II) = 1:1 non-centrosymmetrical homobinuclear dimeric Cu(II) complex, where Cu1 sited in the N 2 O 2 -donor position also coordinates with one phenolic oxygen atom of another ligand (L)2− moiety to construct two discrete metal–ligand [Cu(L)] units. However, Noteworthy, the influence of the interaction of multiple counter-anions and solvents led to the formation of a novel (L)2−: Cu(II) = 2:3 homotrinuclear centrosymmetric sandwich-like dimeric structure in complex 2 , where Cu2 located at the O 6 position bridges two [Cu(L)(EtOH)] metalated ligand moieties. Finally, two novel homopolynuclear dimeric Cu(II) complexes were characterized by elemental analysis, coordination cavities analyses, infrared spectroscopy (IR), electrostatic potential analyses (ESP), interaction region indicator (IRI) analyses and DFT calculation, UV–vis, luminescence spectroscopy and Free regions analyses. [ABSTRACT FROM AUTHOR]

A nonsymmetric salamo-like ligand (H 2 L, 5-(N,N′-diethylamino)-2,2′-[ethylenedioxybis(nitrilomethylidyne)]phenolnaphthol) has been synthesized, and its two homotrinuclear complexes [{Zn 3 (L) 2 (μ -OAc) 2 } 2 ]·5EtOH and [Ni 3 (L) 2 (μ -OAc) 2 (MeOH) 2 ]·2MeOH and single crystals of the ligand have been successfully synthesized and characterized structurally. Molecular electrostatic potential analysis, interaction region indicator analysis, Hirshfeld surfaces analyses, DFT calculations and fluorescent properties of the Zn(Ⅱ) and Ni(Ⅱ) complexes were also studied. [Display omitted] • Single crystals of H 2 L and its Zn(II) and Ni(II) complexes have been determined. • The Zn(II) complex possesses two crystallographically and chemically identical trinuclear clusters. • Experimental and theoretical investigation of the Zn(II) and Ni(II) complexes were performed. Neutral homotrinuclear complexes [{Zn 3 (L) 2 (μ -OAc) 2 } 2 ]·5EtOH and [Ni 3 (L) 2 (μ -OAc) 2 (MeOH) 2 ]·2MeOH were obtained in the reactions of a new non-symmetric salamo-like ligand H 2 L (5-(N,N′-diethylamino)-2,2′-[ethylenedioxybis(nitrilomethylidyne)]phenolnaphthol) with the respective salts of M(OAc) 2 ·2H 2 O (M = Zn(II) and Ni(II)), respectively. Single crystals of the ligand were also obtained. All the Zn(Ⅱ) and Ni(Ⅱ) complexes were structurally characterized by single crystal X-ray diffraction. Both Zn(Ⅱ) and Ni(Ⅱ) complexes are composed of two (L)2− units combined with three metal(Ⅱ) ions, where a pair of μ -OAc− ions bridging Zn1⋯Zn2 and Zn2⋯Zn3 or Ni1⋯Ni2 and Ni2⋯Ni1#1 neutralize the charge of the Zn(II) and Ni(II) complexes and stabilize the trinuclear structure. The two μ -OAc− ions are located on the same side of the Zn(Ⅱ) complex, while on different sides of the Ni(Ⅱ) complex. In addition, there are two methanol molecules in the Ni(Ⅱ) complex involved in the coordination. UV–vis absorption spectral analyses showed that the ligand (L)2− units have coordinated with Zn(Ⅱ) and Ni(Ⅱ) atoms. DFT calculations exhibited that the Zn(II) and Ni(II) complexes have higher kinetic stability and lower chemical reactivity. Fluorescence spectrum analyses indicated that the electrons of the ligand have transferred to the empty orbitals (LMCT) of the Zn(Ⅱ) and Ni(Ⅱ) atoms. Furthermore, to discern the interactions in the crystal structures, Hirshfeld surfaces analyses were evaluated. Molecular electrostatic potentials were calculated in order to find electrophilic and nucleophilic sites favorable for hydrogen bonds. [ABSTRACT FROM AUTHOR]

Two novel complexes [Cu(L)(OAc)]·CH 3 OH (1) and [Ni(L)(OAc)] (2) formed with a quinolone-modified half-salamo-like ligand (HL) were successfully synthesized and characterized structurally. In addition, Fluorescence properties, DFT theoretical calculations and Hirshfeld surfaces analyses of the ligand HL and its corresponding complexes were also investigated. [Display omitted] • The introduction of quinoline into half-salamo-like ligand HL has been developed triumphantly. • Two novel complexes [Cu(L)(OAc)]·CH 3 OH (1) and [Ni(L)(OAc)] (2) were synthesized and ascertained structurally. • Fluorescence properties, DFT theoretical calculation and Hirshfeld surfaces analyses were investigated. Two novel Cu(II) and Ni(II) complexes, [Cu(L)(OAc)]·CH 3 OH (1) and [Ni(L)(OAc)] (2) formed with a newly designed quinolone-modified half-salamo-like ligand (HL) were successfully obtained. Elemental analyses, infrared spectra and UV–visible absorption spectra were employed triumphantly to characterize the complexes 1 and 2. X-ray single-crystal diffraction analysis results indicated that the complex 1 is composed of a fully deprotonated ligand (L)- unit, one Cu(II) atom and one monodentate coordinated acetate ion. For the complex 1 , the central Cu(II) atom is five coordinated adopting a slightly distorted triangular biconical geometry, while the complex 2 has two independent structural units (molecules A and B), which shows chemically identical but crystallographically independent. The central Ni(II) atom is six coordinated possessing a distorted octahedral configuration. In addition, Fluorescence properties, DFT theoretical calculations and Hirshfeld surfaces analyses of the ligand HL and its corresponding complexes 1 and 2 were also investigated in detail. [ABSTRACT FROM AUTHOR]

• The pyridine-including half-salamo-like ligands HL1 and HL2 have been developed successfully. • Two first Co(III) complexes, [Co(L1)(N 3) 2 ] (1), and [Co(L2)(N 3) 2 ] (2) were synthesized and ascertained structurally. • The complexes 1 and 2 are unusual salamo-like Co(III) complexes with variable valence. This situation has never reported in the previous salamo-based complexes. Two structurally novel Co(III) complexes have been successfully constructed from the pyridine-including half-salamo-like ligands (HL1 and HL2), namely as [Co(L1)(N 3) 2 ] (1) and [Co(L2)(N 3) 2 ] (2). The structural features of complexes 1 and 2 have been confirmed by means of single crystal X-ray diffraction experiment. The structural studies revealed that complexes 1 and 2 have similar structures. The characterization of the two ligands and their Co(III) complexes was ascertained by means of infrared spectra, ultraviolet spectra and Hirshfeld surfaces analyses. In addition, compared with the ligands HL1 and HL2, the fluorescence intensities of the corresponding complexes 1 and 2 decreased significantly. When Co(II) salt was gradually added to the ligand solution, the intensity of the fluorescence emission peak decreased with the continuous addition of Co(II) salt until this trend stopped, which indicates that the introduction of Co(II) ion leads to the charge transfer from the ligand to Co(III) ion. Two structurally novel Co(III) complexes have been successfully constructed from the pyridine-including half-salamo-like ligands (HL1 and HL2), namely as [Co(L1)(N 3) 2 ] (1) and [Co(L2)(N 3) 2 ] (2). The characterization of the two ligands and their Co(III) complexes was ascertained by means of infrared spectra, ultraviolet spectra, X-ray crystallography, fluorescence spectra and Hirshfeld surfaces analyses. [Display omitted] [ABSTRACT FROM AUTHOR]

• A new kind of single‐armed salamo‐type ligand H 3 L and two corresponding Zn(II) complexes have been synthesized. • All of the Zn(Ⅱ) atoms in complexes 1 and 2 are penta-coordinated, highly distinct configurations are obtained because of the introduction of two kinds of counter-anions. • Fluorescence properties of H 3 L and complexes 1 and 2 were also investigated. Di- and tetra-nuclear Zn(II) complexes, [Zn 2 (L)(µ -OAc)(CH 3 OH)]·CH 3 OH (1) and [Zn 4 (L) 2 (OMe) 2 ]·2CH 3 COCH 3 ·CH 3 OH (2) have been successfully self-assembled by the reaction of a single‐armed salamo‐type ligand (H 3 L), Zn(OAc) 2 ·2H 2 O and Zn(NO 3) 2 ·6H 2 O, respectively. In the ligand H 3 L, tetradentate N 2 O 2 donor part of pocket I and NO 2 donor part of pocket II are designed to bond Zn(II) atoms, then unusually structural complexes were obtained by counteranion-driven self-assembled. Both complexes 1 and 2 are characterized by elemental analyses, IR spectra, UV-Vis spectra and single crystal X-ray diffraction. All of the Zn(II) atoms in complexes 1 and 2 are penta-coordinated, but highly distinct configurations are obtained because of the introduction of two kinds of counter-anions. In complex 1 , μ- OAc− counter-anion connects the two Zn(II) atoms in one ligand. In complex 2 , μ- OMe− counter-anions link the Zn(II) atoms within two ligand molecules and the structure of complex 2 is more complicated. What's more, in complex 1 , all Zn(II) atoms have the geometries of distorted trigonal bipyramid, while in complex 2 , all Zn(II) atoms have the geometries of distorted square pyramid. There are obvious π···π stacking interactions existing in complexes 1 and 2 , which are quantitatively valued by Hirshfeld surfaces analyses. Fluorescence properties are also investigated. Di- and tetra-nuclear Zn(II) complexes, [Zn 2 (L)(µ -OAc)(CH 3 OH)]·CH 3 OH (1) and [Zn 4 (L) 2 (OMe) 2 ]·2CH 3 COCH 3 ·CH 3 OH (2) have been successfully synthesized and structurally characterized. The fluorescence properties were also investigated. [Display omitted] [ABSTRACT FROM AUTHOR]

A newly designed symmetrical bis(salamo)-type tetraoxime ligand H 3 L and its two novel di- and tetra-nuclear Cu(II) complexes 1 and 2 have been successfully synthesized and characterized structurally. Hirshfeld surfaces and fluorescence properties of the two complexes were investigated in detail. [Display omitted] Two kind of structurally different bis(salamo)-type polynuclear Cu(II) complexes, including [Cu 2 (HL)(EtOH)Cl 2 ]·CH 2 Cl 2 (1), [Cu 4 (L) 2 (EtOH) 2 ](NO 3) 2 ·2EtOH (2) have been prepared by the reactions of the ligand H 3 L with CuCl 2 ·2H 2 O and Cu(NO 3) 2 ·3H 2 O, respectively. The crystal structures of complexes 1 and 2 were characterized by X-ray crystallographic examination. Complex 1 crystallizes in triclinic system, P −1 space group, forming a unique homo-dinuclear Cu(II) complex consisting of two Cu(II) ions, one inadequately deprotonated ligand (HL)2− unit, and one ethanol molecule. The fundamental structure of complex 2 with centrosymmetric double-helical structure is two totally deprotonated ligand (L)3− units, two central Cu(II) atoms, and two coordinated ethanol molecules, which crystallizes in monoclinic system, P 2 1 /c space group. Complexes 1 and 2 constructed by the bis(salamo)-type ligand are built into three-dimensional and two-dimensional frameworks by intermolecular interactions. Hirshfeld surfaces studies were used to quantify the various interactions of complexs 1 and 2. The spectral properties of complexes 1 and 2 were studied by ultraviolet and infrared spectroscopy. Moreover, fluorescence characteristics are carried out. Undoubtedly, these studies can enrich the structural diversity of bis(salamo)-type Cu(II) complexes. [ABSTRACT FROM AUTHOR]

• A new heterobimetallic [Cu(II) 2 Pr(III)] complex with a symmetric flexible bis(salamo)-type ligand was synthesized and characterized structurally. • There are two different metal-binding sites of N 2 O 2 and O 6 (two being specific for the 3d metal ions and the other for the 4f metal ion) for the synthesis of heteropolynuclear 3d-4f complex with a flexible bis(salamo)‐type ligand. • Hirshfeld surface analysis and luminescence of the [Cu(II) 2 Pr(III)] complex was investigated. A new heterobimetallic 3d-4f [Cu(II) 2 Pr(III)] complex [Cu 2 Pr(L)(ƞ 2-NO 3) 3 (EtOH) 2 ]·2EtOH with a symmetric flexible bis(salamo)-type ligand, (1E,1′E)-2,3-dihydroxynaphthalene-1,4-dicarbaldehyde O,O -di(3-((((E)-3-ethoxy-2-hydroxybenzylidene)amino)oxy)propyl)dioxime (H 4 L), has been synthesized and characterized structurally. Single crystal X-ray diffraction analysis showed that the ligand was fasten by different metal ions to form a hetero-trinuclear complex with C-shaped structure, where two N 2 O 2 -donors of the completely deprotonated ligand (L)4− unit and two oxygen atoms from two ethanol molecules coordinate with Cu(II) atoms (Cu1, Cu2), respectively, to form two five-coordinated square pyramid geometries. Meanwhile, where the O 6 cavity coordination sphere of the ligand (L)4− unit and six oxygen atoms from three nitrate groups coordinate with the Pr(III) atom together to form a twelve-coordinated icosahedron. Due to the Cu(II) atom in the O 6 cavity was replaced by the Pr(III) atom, it shows that the hetero-trinuclear complex after self-assembly is more stable than the homo-trinuclear complex. At the same time, through UV–Vis titration spectrometric analysis, we can observed that the hetero-trinuclear [Cu(II) 2 Pr(III)] complex is obtained by 1 equiv. Pr(NO 3) 3 ·5H 2 O and 2 equiv. Cu(NO 3) 2 ·3H 2 O and 1 equiv. H 4 L. Significantly, fluorescence properties and Hirshfeld surfaces analyses of the [Cu(II) 2 Pr(III)] complex was also studied. A new heterobimetallic [Cu(II) 2 Pr(III)] complex with a symmetric flexible bis(salamo)-type ligand, (1E,1′E)-2,3-dihydroxynaphthalene-1,4-dicarbaldehyde O,O-di(3-((((E)-3-ethoxy-2-hydroxybenzylidene)amino)oxy)propyl)dioxime (H 4 L), has been synthesized and characterized structurally. Two five-coordinated Cu(II) atoms and one twelve-coordinated icosahedron Pr(III) atom are located in different coordination environments, respectively, fluorescence properties, Hirshfeld surfaces analyses and DFT calculations of the [Cu(II) 2 Pr(III)] complex was also studied. [Display omitted]. [ABSTRACT FROM AUTHOR]

• A reversible on-off fluorescent probe H2LS with high selectivity and sensitivity was developed. • It is showed that one of the two oxime-oxygen atoms of the probe (LS)2- unit is involved in the coordination with Cu(II) atom. • H2LS can be successfully applied for the determination of Cu2+ ions in real water samples. A salamo-based fluorescent probe H 2 L S was synthesized by grafting 3-tert-butyl-5-bromosalicylaldehyde and 2-hydroxy-1-naphthaldehyde onto 1, 2-bis(aminooxy)ethane. The probe can selectively and sensitively recognize Cu2+ ions, accompanied by a significant fluorescence quenching change from blue fluorescence to no fluorescence, and the probe can rapidly respond to Cu2+ ions in a short time. Meanwhile, there is a linear relationship between the fluorescence intensity at 393 nm and the concentration of Cu2+ ions (0.05–10 mM). Therefore, the probe can realize the quantitative detection of Cu2+ ions in aqueous solutions with a low detection limit of 4.64 × 10−7 M. In addition, X–ray structure analysis of the Cu(II) complex of H 2 L S showed that one of the two oxime-oxygen atoms of the probe (L S)2− unit is involved in the coordination with Cu(II) atom. The density functional theory (DFT) was validated to further confirm the recognition mechanism of the probe H 2 L S to Cu2+ ions. An on-off fluorescent probe H 2 L S was developed. The crystal structure analysis of its Cu(II) complex showed that one of the two oxime-oxygen atoms of the probe (L S)2− unit is involved in the coordination with Cu(II) atom. The Job's plot and ESI-MS spectra showed that the probe adopts a 1:1 binding mode with the Cu2+ ions, with a binding constant of 3.99 × 107 M−1, and the result is in agreement with the single crystal X-ray diffraction analysis. Furthermore, the probe can realize an excellent selectivity, rapid response, recoverability and has also been successfully applied to the quantification of Cu2+ ions in real samples. [Display omitted] [ABSTRACT FROM AUTHOR]

• Two new fluorescent chemical sensors, H 4 L and its L-Cu2+ complex, are reported for the selective detection of Cu2+ and S2− ions in DMF solution, respectively. • The crystal structure of the L-Cu2+ complex was determined by X-ray crystallography, and Hirshfeld surface analysis was described. • The recognition mechanisms of the chemical sensor H 4 L and its L-Cu2+ complex were analyzed by density functional theory (DFT) and mass spectrometry. Two new fluorescent chemical sensors, H 4 L and its L-Cu2+ complex, are reported for the selective detection of Cu2+ and S2− ions in DMF solution, respectively. In the fluorescent switch structure of chemical sensor H 4 L, the binding of Cu2+ ions in the receptor part leads to the coordination between the completely deprotonated ligand (L)4− unit and Cu2+, resulting in fluorescence quenching. S2− was added to the L-Cu2+ complex to turn on the fluorescence of the L-Cu2+ complex. The chemical sensor H 4 L and its L-Cu2+ complex can possess obvious selectivities for common cations and anions in the micro molar concentration range, so as to quantitatively detect Cu2+ and S2− ions. The interaction of S2− ions with the chemical sensor L-Cu2+ was investigated by fluorescence time response measurement, whereas high-resolution mass spectrometry, and fluorescent titration substantiated the stoichiometry between L-Cu2+ and S2− ions. The crystal structure of the L-Cu2+ complex, [Cu 2 (L)]·2CHCl 3 has been determined by X-ray crystallographic analysis. Density Functional Theory (DFT) calculations were performed in order to show the structures and electronic properties of H 4 L and its L-Cu2+ complex. [Display omitted]. [ABSTRACT FROM AUTHOR]

Two octahedral homopolynuclear Ni(II) complexes, [Ni 2 (L)(OAc)(MeOH)]·CH 3 CN·MeOH (1) and [Ni 4 (L) 2 (acac) 2 (EtOH) 2 ]·2CH 3 CN (2) have been synthesized and characterized structurally. Hirshfeld surfaces, DFT calculation and fluorescence properties of complexes 1 and 2 were investigated. [Display omitted] • Anion-solvent-dependent construction of two homopolynuclear Ni(II) complexes 1 and 2 were synthesized and characterized structurally. • Complex 2 possesses a novel centrosymmetric tetra-nuclear structure with two dinuclear [Ni 2 (L)(acac)(EtOH)] units. • Hirshfeld surfaces, DFT calculation and fluorescence properties of complexes 1 and 2 were investigated. Two counteranion-solvent-dependent homopolynuclear Ni(II) complexes, [Ni 2 (L)(OAc)(MeOH)]·CH 3 CN·MeOH (1) and [Ni 4 (L) 2 (acac) 2 (EtOH) 2 ]·2CH 3 CN (2) have been constructed by exploiting the flexibility of a symmetrical multi-halogen-substituted bis(salamo)-based ligand H 3 L. The structures of complexes 1 and 2 were confirmed by single crystal X-ray diffraction studies. Complex 1 is a di-nuclear Ni(II) complex, where two octahedral Ni(II) atoms are located in the N 2 O 2 cavities of the salamo units, and bridged via a acetate ion. Complex 2 possesses a centrosymmetric tetra-nuclear structure with two di-nuclear [Ni 2 (L)(acac)(EtOH)] units. It is worth noting that one acetylacetonate anion is coordinated to Ni2 atom in bidentate fashion along with one methanol molecule that completes its hexa-coordinated geometry. It is possible that the existence of the acetylacetone anion makes the ligand (L)3- unit exhibit its flexibility, which promotes the formation of tetra-nuclear complex 2. The close surveillance of the crystal structure of complexes 1 and 2 discloses some notable non-covalent interactions like H-bonding, C H⋯π and π⋯π. Moreover, both complexes 1 and 2 form three-dimensional supramolecular structures with the help of intermolecular hydrogen bonds. It was found that the synthesis of complexes 1 and 2 weakened the fluorescence intensity of H 3 L until quenching. Hirshfeld surfaces analyses confirmed that hydrogen bond interactions play the most important role in the stability of crystal structures. The high kinetic stability and low chemical reactivity of complexes 1 and 2 were investigated based on the band gap energy. [ABSTRACT FROM AUTHOR]

A highly selective and effective bis(salamo)-based fluorescent sensor (H 3 L) was designed and synthesized for the two-pronged sensing of copper(II) ions (Cu2+) and arginine (Arg). Additionally, the test strip can be used to detect Arg visible to the naked eye. [Display omitted] • A novel bis(salamo)-like probe (H 3 L) is highly selective as well as sensitive to Cu2+ and Arg. • The recognition mechanism of the sensor H 3 L for Cu2+ was studied by X-ray crystallography. • Test strips are available for fast visual identification of Arg using the sensor H 3 L. A novel salamo-based fluorescent sensor H 3 L was synthesized and characterized by IR, 1H NMR and ESI-MS. The results showed that the fluorescence spectra and UV–Vis absorption spectra of H 3 L changed with the addition of Cu2+ and Arg respectively. The introduction of Cu2+ ions caused significant fluorescence quenching. The combination of Cu2+ ions and the sensor was confirmed by X-ray crystallography of the copper(II) complex [{Cu 2 (L)} 2 ](ClO 4) 2 ·H 2 O, which can lead to fluorescence quenching through coordination coupling. The response of the amino acid Arg to H 3 L was turned on by fluorescence and their combination was characterized by IR and ESI-MS. The sensitivity of the fluorescence response to Cu2+ ion and Arg was determined by their LODs 6.5084 × 10−8 M and 1.7271 × 10−7 M, respectively. At the same time, it was determined by titration experiments that H 3 L and Cu2+ ions are combined at a ratio of 1:2, and 1:1 with Arg. Calculating their binding constants are 6.91 × 109 M−1 and 3.17 × 109 M−1, respectively. [ABSTRACT FROM AUTHOR]

Three novel N 4 -cavity Cu(II), Ni(II) and Zn(II) complexes were successfully synthesized via the reactions of a novel pyridine-containing N 4 -cavity bisoxime ligand L. All three complexes are monoclinic systems. Complexes 2 and 3 form centrosymmetric helical molecules. Complexes 1 – 3 have been characterized by elemental analysis, IR, UV–Vis spectroscopy and single crystal X-ray crystallography. In addition, supramolecular interactions, Hirshfeld surface analysis to analyze the crystal properties have been studied. [Display omitted] • A novel ligand L with N4 cavity was synthesized and characterized. • Three excess metal single crystals were synthesized via the ligand L. • Hirshfeld surface analysis was performed on single crystals. Three novel N 4 -cavity Cu(II), Ni(II) and Zn(II) mononuclear complexes, [Cu(L)(NO 3) 2 ][Cu(L)(NO 3)]NO 3 (1) [Ni(L)(NO 3) 2 ] (2) and [Zn(L)(NO 3) 2 ] (3) were successfully synthesized via the reactions of a pyridine-containing N 4 -cavity bisoxime ligand L (L = 2,2′-[Ethylenedioxobis(azetidinyl)]pyridine) with Cu(II), Ni(II) and Zn(II) nitrates, respectively. Complexes 1 – 3 were characterized via elemental analysis, IR, UV–Vis spectra and X-ray crystallography. All three complexes are monoclinic systems, containing one M(II) atom and one (L) ligand moiety. Complexes 2 and 3 form centrosymmetric molecules. In addition, supramolecular interactions, Hirshfeld surface analysis were used to analyze the crystal properties that have been studied. [ABSTRACT FROM AUTHOR]