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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]

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]

A family of rare structurally different homometal multinuclear CuII bis(salamo)‐based complexes, [Cu4(L)2(MeOH)2](ClO4)2·2MeOH (1), [Cu4(L)2(EtOH)2](NO3)2·2EtOH (2) and [Cu2(HL)(EtOH)Br2]·CHCl3 (3), has been successfully synthesized by the reactions of cupric salts with a bis(salamo)‐based multidentate chelate ligand (H3L). The salamo‐based ligand [R‐CH=N—O—(CH2)n—O—N=CH—R] is a new type of salen‐based analog. Complexes (1) and (2) are isostructural structures, and crystallize in monoclinic space group P21/n with centrosymmetric spiral structures, where the main structures contain two fully deprotonated ligand (L)3− units, a charged tetranuclear CuII folding center and two coordinated solvent molecules. Complex (3) crystallizes in monoclinic space group Cc and consists of two CuII cations, one incompletely deprotonated ligand (HL)2− unit and one coordinated ethanol molecule, and forms a novel homo‐binuclear CuII complex structure due to Br− counter anions. Complexes (1)–(3) have zero‐dimensional cluster‐based structures and are further assembled into three‐dimensional frameworks via intermolecular interactions. Because of the different solvents and counter anions which have a significant influence on the structures of complexes (1)–(3), the interactions were quantitatively evaluated by Hirshfeld surfaces analyses. Complexes (1)–(3) have been characterized by elemental analyses, IR spectra, UV–vis spectra and X‐ray crystallography analyses. In addition, fluorescence properties are evaluated and DFT calculations are performed. [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]

Three novel multinuclear NiII complexes, namely, bis{μ‐2‐methoxy‐6‐[8‐(pyridin‐2‐yl)‐3,6‐dioxa‐2,7‐diazaocta‐1,7‐dien‐1‐yl]phenolato}bis[thiocyanatonickel(II)], [Ni2(L)2(NCS)2], 1, bis{μ‐2‐methoxy‐6‐[8‐(pyridin‐2‐yl)‐3,6‐dioxa‐2,7‐diazaocta‐1,7‐dien‐1‐yl]phenolato}bis[azidonickel(II)], [Ni2(L)2(N3)2], 2, and catena‐poly[[{2‐methoxy‐6‐[8‐(pyridin‐2‐yl)‐3,6‐dioxa‐2,7‐diazaocta‐1,7‐dien‐1‐yl]phenolato}nickel(II)]‐μ‐dicyanamidato], [Ni(L)(dca)]n, 3 {dca is dicyanamide, C2N3, and HL is 2‐methoxy‐6‐[8‐(pyridin‐2‐yl)‐3,6‐dioxa‐2,7‐diazaocta‐1,7‐dien‐1‐yl]phenol, C16H17N3O4}, with a half‐salamo‐based pyridine‐containing HL ligand have been synthesized and characterized by FT–IR, UV–Vis absorption spectroscopy, X‐ray crystallography, Hirshfeld surface analysis and density functional theory (DFT) calculations. The central NiII ions in complexes 1–3 are hosted in the half‐salamo‐based N3O‐donor cavity of the organic ligand. Complex 1 is a centrosymmetric dimer and two [Ni(L)(NCS)] units form a centrosymmetric dimeric structure, which is bridged by two phenolate O atoms. The two N atoms at the axial ends are provided by two NCS− ligands. In complex 1, each NiII ion has a six‐coordinated octahedral geometry. Complex 2 is similar to 1, but they differ in that the auxiliary NCS− ligand is replaced by N3−. However, complex 3 is a one‐dimensional coordination polymer constructed from [Ni(L)(dca)] units, which are connected by the auxiliary bidentate dca ligand viaN‐donor atoms. As with complexes 1 and 2, the NiII ion in 3 has a six‐coordinated octahedral geometry. [ABSTRACT FROM AUTHOR]

An unexpected trinuclear Co(II) complex, [Co3(L2)2(μ-OAc)2(CH3OH)2]·2CH3OH (H2L2 = 4,4′-dibromo-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol) constructed from a half-Salamo-based ligand (HL1 = 2-[O-(1-ethyloxyamide)]oxime-4-bromophenol) and Co(OAc)2·4H2O, has been synthesized and characterized by elemental analyses, infrared spectra (IR), UV-Vis spectra, X-ray crystallography and Hirshfeld surface analysis. The Co(II) complex contains three Co(II) atoms, two completely deprotonated (L2)2− units, two bridged acetate molecules, two coordinated methanol molecules and two crystalline methanol molecules, and finally, a three-dimensional supramolecular structure with infinite extension was formed. Interestingly, during the formation of the Co(II) complex, the ligand changed from half-Salamo-like to a symmetrical single Salamo-like ligand due to the bonding interactions of the molecules. In addition, the antimicrobial activities of HL1 and its Co(II) complex were also investigated. [ABSTRACT FROM AUTHOR]

A new homo-trinuclear Ni(II) half-salamo-based complex [Ni3(L)2(μ-OAc)2(OAc)2(CH3OH)2]·2CH3OH was synthesized via the reaction of a tridentate ligand HL (2-[O-(1-ethyloxyamide)]oxime-4-bromophenol) and Ni(OAc)2·4H2O, and characterized using elemental analyses, IR spectra, UV-Vis absorption spectra, X-ray crystallography, and Hirshfeld analysis. Interestingly, single-crystal X-ray analysis showed that the two acetate molecules were bonded simultaneously with the Ni(II) atoms by mono-dentate chelating and bidentate bridging coordination modes, respectively, and the resulting hexa-coordinate geometries were ultimately formed. Furthermore, the Hirshfeld analysis of the complex was studied. Compared with HL, the complex fluorescence intensity was significantly lowered, indicating that the Ni(II) ions have fluorescence quenching characteristics. [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]

Graphical abstract Homo-trinuclear [Zn 3 (L)(μ 2 -OAc) 2 (H 2 O)] . CH 2 Cl 2 (1) and hetero-pentanuclear [Zn 4 (L) 2 Eu(NO 3) 3 (H 2 O)] (2) and [Zn 4 (L) 2 Nd(NO 3) 3 (H 2 O)]·CH 3 CH 2 OH (3) complexes containing a coumarin-skeleton bis(salamo)-like ligand H 4 L, were successfully prepared and structurally characterized. Hirshfeld surfaces analysis and luminescences were investigated in detail. Highlights • Trinuclear ZnII (1) and pentanuclear ZnII-LnIII (Ln = Eu (2) and Nd (3)) complexes were synthesized. • The structures of complexes 1 – 3 are reported. • Hirshfeld surface and luminescences of complexes 1 – 3 were investigated. Abstract Homo-trinuclear [Zn 3 (L)(μ 2 -OAc) 2 (H 2 O)] . CH 2 Cl 2 (1) and hetero-pentanuclear [Zn 4 (L) 2 Eu(NO 3) 3 (H 2 O)] (2) and [Zn 4 (L) 2 Nd(NO 3) 3 (H 2 O)]·CH 3 CH 2 OH (3) complexes containing a coumarin-skeleton bis(salamo) ligand H 4 L, were successfully prepared and characterized via the means of elemental analyses, single crystal X-ray crystallography, FT-IR, UV–Vis absorption spectroscopy and Hirshfeld surfaces analyses. Complex 1 is a 1:3 ((L)4−:ZnII) structure, and complexes 2 and 3 are 2:4:1 ((L)4−:ZnII:LnIII) structure. All ZnII atoms in complexes 1 – 3 occupied the N 2 O 2 sites are five-coordinated with geometries of slightly distorted tetragonal pyramid and trigonal bipyramid. Rare earth metal (EuIII and NdIII) atoms are both coordinated with phenolic oxygen atoms, and eight-coordinated with the square antiprism geometries in complexes 2 and 3. Water molecules as coordinating solvents participate in the coordination. Supra-molecular structures are built by C H ... π and hydrogen bonding interactions in complexes 1 – 3. Moreover, Hirshfeld surfaces analyses of complexes 1 – 3 were also analysed in detail. Most important of all, luminescences of complexes 1 – 3 were discussed. [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]

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]

A new salamo-type probe H 2 L and its Co2+ complex [Co 3 (L) 2 (MeOH) 2 (μ -OAc) 2 ]·2MeOH were synthesized and characterized structurally. Fluorescence of Co2+ selectively response showed "off" when cations were sequentially detected. Meanwhile, the mechanism of recognition of Co2+ by H 2 L was got. DFT calculation and Hirshfeld surfaces analyses were investigated to further understand the experimental results observed. [Display omitted] • The probe H 2 L could efficiently detect Co2+ ion. • The probe H 2 L could detect Co2+. Meanwhile, H 2 L and Co2+ complex were characterized. • Hirshfeld surfaces analyses and DFT calculation were studied. A new salamo-type fluorescence probe H 2 L was synthesized by a series of reactions and corroborated by single-crystal X-ray crystallography and 1H NMR spectra. Fluorescence of Co2+ selectively response showed "off" when cations were sequentially detected. The LOD of H 2 L to Co2+ was calculated to be 3.73 × 10-7 M in DMF/water (9:1, v/v) solution system. Meanwhile, the single crystal of the Co2+ complex with H 2 L was obtained by solvent evaporation. The structure of the complex [Co 3 (L) 2 (MeOH) 2 (μ -OAc) 2 ]·2MeOH was validated by single-crystal X-ray diffraction, IR, and elemental analyses, and the mechanism of recognition of Co2+ by H 2 L was got. Density functional theory (DFT) and Hirshfeld surface analyses were investigated to further understand the experimental results observed. [ABSTRACT FROM AUTHOR]

Three trinuclear complexes 1 - 3 possessed inversion centers have been successfully synthesized by wet-chemical method using asymmetric salamo-based polydentate chelating ligand (H 2 L) with Co(OAc) 2 ·4H 2 O and Ni(OAc) 2 ·4H 2 O, respectively. [Display omitted] Three trinuclear complexes, [{CoL(MeOH)(μ -OAc)} 2 Co] (1), [{CoL(EtOH)(μ -OAc)} 2 Co]·2CH 3 CH 2 OH (2) and [{NiL(MeOH)(μ -OAc)} 2 Ni]·2CH 3 OH (3) have been successfully synthesized by wet-chemical method using asymmetric salamo-based polydentate chelating ligand (H 2 L) with transition metal(II) acetate (Co(OAc) 2 ·4H 2 O or Ni(OAc) 2 ·4H 2 O). The ligand H 2 L with N 2 O 2 coordination cavity can accommodate transition metals, at the same time, the oxygen atoms of the phenolic hydroxyl groups can bridge the metal atoms to obtain muiltnuclear metal complexes. There are inversion centers in complexes 1 – 3 and all M(II) atoms possess six-coordinated distorted octahedral geometries. Complexes 1 and 3 are further assembled into extended two-dimensional supramolecular via intermolecular interactions, but complex 2 forms three-dimensional supramolecular structure. The interactions were quantitatively determined by Hirshfeld surfaces analyses. Significantly, complexes 1 – 3 have been characterized by elemental analyses, IR spectra, UV–Vis spectroscopy and X-ray crystallography analyses. Fluorescence properties were also investigated. [ABSTRACT FROM AUTHOR]

Penta-coodinated homo-binuclear [Cu 2 (L)(CH 3 OH)]ClO 4 ·CH 3 OH (1) , [Cu 2 (L)(CH 3 CH 2 OH)]ClO 4 (2) and homo-tetranuclear [{Cu 2 (HL)Cl(μ -Cl)} 2 2CHCl 3 (3) complexes containing a symmetrical multi-halogen-substituted bis(salamo)-based ligand H 3 L have been successfully synthesized and characterized by elemental analyses, FT-IR and UV–Vis absorption spectroscopy, fluorescence spectra, Hirshfeld surfaces analyses and density functional theory (DFT) calculations. [Display omitted] • Di- and tetranuclear complexes 1 , 2 and 3 were synthesized and characterized structurally. • The complex 3 possesses a novel tetranuclear structure in which the two [Cu 2 (HL)Cl] units are bridged by two chloride anions. • Hirshfeld surfaces, DFT calculation and luminescences of three Cu(II) complexes were investigated. Penta-coordinated homo-binuclear [Cu 2 (L)(CH 3 OH)]ClO 4 ·CH 3 OH (1) , [Cu 2 (L)(CH 3 CH 2 OH)]ClO 4 (2) and homo-tetranuclear [{Cu 2 (HL)Cl(μ -Cl)} 2 ·2CHCl 3 (3) complexes containing a symmetrical multi-halogen-substituted bis(salamo)-based ligand H 3 L have been successfully synthesized and characterized by elemental analyses, FT-IR and UV–Vis absorption spectroscopy, Hirshfeld surfaces analyses and density functional theory (DFT) calculations. The crystal structures of the three Cu(II) complexes were determined by single crystal X-ray crystallography. All the Cu(II) atoms in the binuclear complexes 1 and 2 are located in the N 2 O 2 cavities of the fully deprotonated (L)3- unit, and penta-coordinated with slightly distorted square pyramidal geometries. Methanol and ethanol molecules are coordinated to the Cu(II) atoms in the complexes 1 and 2 , respectively. Most surprisingly, the complex 3 has a novel penta-coordinated tetranuclear structure unreported earlier. The four Cu(II) atoms in the complex 3 are all penta-coordinated, and the geometries around the Cu(II) centers in complexes 3 are square pyramid. It is worth noting that two binuclear [Cu 2 (HL)Cl] units are connected to two bridged chloride ions and the complex 3 has a crystallographically imposed inversion center at the midpoint of Cu2 and Cu2#1. The supramolecular structures of the complexes 1 , 2 and 3 are formed by inter-molecular interactions. In addition, Hirshfeld surfaces analyses showed short-range interactions on the molecular surfaces of the complexes 1 , 2 and 3. Furthermore, the fluorescence properties of H 3 L and its three Cu(II) complexes are also discussed. [ABSTRACT FROM AUTHOR]

Two newly designed tetranuclear metal(II) complexes, [{Co(L)(μ -OAc)Co(CH 3 OH) 2 } 2 and [{Ni(L)(DMF)(μ -OAc)Ni} 2 derived from an unsymmetrical salamo-like ligand (H 3 L: 6-hydroxy-6′-methoxy-2, 2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol) were synthesized and characterized by elemental analyses, infrared spectroscopy, ultraviolet–visible absorption spectroscopy, fluorescence spectroscopy, X-ray single crystal diffraction and Hirshfeld surfaces analyses. • Tetranuclear Co(II) and Ni(II) complexes were synthesized and characterized structurally. • The crystal structures of Co(II) and Ni(II) complexes are very interesting. • Hirshfeld surfaces and fluorescent properties of the Co(II) and Ni(II) complexes were investigated. Two newly designed tetranuclear transition metal(II) complexes, [{Co(L)(μ -OAc)Co(CH 3 OH) 2 } 2 and [{Ni(L)(DMF)(μ -OAc)Ni} 2 derived from an unsymmetrical salamo-like donor-N 2 O 4 ligand (H 3 L: 6-hydroxy-6′-methoxy-2, 2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol) were synthesized and characterized by elemental analysis, FT-IR, UV-vis, fluorescence spectroscopy, X-ray crystallography and Hirshfeld surface analysis. The Co(II) complex includes two fully deprotonated (L)3− moieties, two μ-acetato ligands and four coordinated methanol molecules, bearing a highly symmetrical tetranuclear structure. The terminal Co(II) ions are penta-coordinated and have slightly twisted triangular bipyramidal geometries, and the central Co(II) ions are hexa-coordinated and possess slightly twisted octahedral geometries. The Co(II) complex was self-assembled by adequate intermolecular hydrogen bonding interactions giving rise to an infinite two-dimensional supramolecular structure. The Ni(II) complex adopts a symmetric tetranuclear structure including two fully deprotonated (L)3− units, two coordinated DMF molecules, and two μ-acetato ligands. All the Ni(II) ions are hexa-coordinated and have slightly twisted octahedral geometries. At the same time, the fluorescent properties and Hirshfeld surfaces analyses of the Co(II) and Ni(II) complexes were also investigated in detail. [ABSTRACT FROM AUTHOR]