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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 design, synthesis, physical properties, and calculated detonation performances of two skeleton isomeric energetic compounds containing tetrazole were introduced. By changing the chemical modification sites of the original fused-pyrimidine skeleton, a new pyrazolo[5,1-c][1,2,4]triazine framework was designed to compensate for the inability to functionalize CH sites in the original backbone. The potential energetic molecule 4-amino-8-nitro-3-(1H-tetrazol-5-yl)pyrazolo[5,1-c][1,2,4]triazin-7(6H)-one (PTT) was synthesized and characterized, which exhibits a moderate thermal decomposition temperature of 278.8 °C, good detonation velocity of 8620 m s−1, and desirable mechanical sensitivity. A comprehensive comparison between original 2-nitro-6-(1H-tetrazol-5-yl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-amine (NPT) and PTT suggests that positional isomerism modulation holds broad prospects in the design of energetic materials. [ABSTRACT FROM AUTHOR]

Determining the surface structure and morphology under working conditions is essential to obtain facet-dependent catalytic performance. However, the evolution of the morphology and exposed surfaces of nanocatalysts is sensitive to experimental conditions such as temperature and gaseous pressure, which brings about a great experimental challenge to obtain this information. Herein, ab initio thermodynamics, density functional theory and Wulff morphology were employed to investigate the surface structure and morphology evolution of HCP-Co under hydrogen-relevant conditions. From the stepwise adsorption on each facet of HCP-Co, hydrogen prefers to adsorb on threefold hollow sites. The morphology of HCP-cobalt presents a quasi-spherical shape and the main exposed surfaces of HCP-Co are (0001), (10-10), (10-11) and (10-12) under different temperatures and hydrogen partial pressures. This work provides complementary information to experimental studies for knowing the microstructures of cobalt nanocatalysts in hydrogen-involved reactions. [ABSTRACT FROM AUTHOR]

Based on tetraphenylethylene as the skeleton, two novel salamo-type fluorescent probes (TPES1 = 2-hydroxy-1-naphthaldehyde O-(3-(((-2-hydroxy-5-(1,2,2-triphenylvinyl)benzylidene)amino)oxy)propyl) oxime and TPES2 = bis(2-hydroxy-1-naphthaldehyde O-(3-(((2-hydroxy-5-(1,2,2-triphenylvinyl)benzylidene)amino)oxy)propyl) dioxime) were designed and synthesized. Through the colorimetric and fluorescence dual-channel modes, cyanide ions could be specifically recognized by the two probe molecules. Interestingly, the probes TPES1 and TPES2 exhibited completely different spectral behaviors during the recognition process. Of the two, the TPES1 molecule is a ratio-type fluorescent probe, and double fluorescence emission peaks appeared during the titration process. The reason for this phenomenon is due to the rotation of the C–C single bond in tetraphenylethylene, causing the solution system to contain molecules in two states. On the other hand, the TPES2 molecule is a fluorescence-enhanced probe that has undergone two reaction processes of deprotonation and addition reaction successively, causing the fluorescence intensity to increase continuously. Theoretical calculations indicated that the configuration of probe TPES1 is reversed after interacting with cyanide ions (CN−). By calculating the minimum detection limits of TPES1 and TPES2 to CN−, the LOD values were 8.56 × 10−8 M and 5.37 × 10−8 M, respectively. In addition, probe-based test strips have been prepared for quick and simple detection of cyanide ions. [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, simple and easy-to-manufacture highly selective and sensitive dual-mode sensor A1, is used for CN− colorimetric and fluorescence detection. Interestingly, the solid powder of sensor A1 emits a strong green fluorescence, and has aggregation-induced emission properties. Single crystal diffraction analysis results prove that the generation of AIE properties is based on the J-aggregation mechanism. Simultaneously, A1 showed high selectivity and sensitivity to CN− in many interfering anions. The sensing mechanism of cyanide is carried out by deprotonation of the –OH group by the cyanide ion, and has been confirmed by spectroscopic studies, 1H NMR spectroscopy, Job's plot analyses and DFT calculation. The practicality of the sensor has been well proven by filter paper strips and small molecule smart fluorescent display materials. In addition, the sensor is used to detect cyanide in food materials (such as germinated potatoes, cassava and bitter almonds) with satisfactory results. The most important thing is considering the colorimetric and fluorescent dual modes, the ultra-fast response, excellent selectivity and recyclability that demonstrate its excellent value in practical applications. [ABSTRACT FROM AUTHOR]

Two heteropolynuclear complexes, namely [Cu2(L)Ce(NO3)3] and [{Cu2(L)Y(NO3)2(μ-AcO)}{Cu2(L)Y(NO3)2(μ-NO3)(CH3OH)}]·4CH3OH, were synthesized through the reaction of a newly synthesized bis(salamo)-based ligand (H4L), Cu(OAc)2·H2O and Ln(NO3)3·6H2O (Ln = Ce and Y), respectively. Single crystal structure analyses showed that the [CuII2CeIII] and [CuII4YIII2] complexes contained similar trinuclear [CuII2LnIII] structures. The difference was that the [CuII4YIII2] complex consisted of two crystallographically independent and chemically different trinuclear complexes with coordination and free solvent molecules. Among the two heteropolynuclear metal complexes, only the [CuII2CeIII] complex showed catecholase activity and benzoxazinone synthase activity under normal temperature and aerobic conditions. For catecholase activity, the calculated Kcat of the [CuII2CeIII] complex was 346.5 h−1, and the Kcat of p-benzoxazinone synthase activity was 9.73 h−1. Compared with the [CuII4YIII2] complex, we speculated that the main reason for the high catalytic function of the [CuII2CeIII] complex is the presence of three nitrate groups coordinated with the central CeIII atom. Evidence from mass spectrometry and cyclic voltammetry curves indicated that there may be heterometallic cooperation, in which CeIII binds to the substrate, while the metallic copper transformed between CuII and CuI through redox reactions. In addition, the catalytic mechanism was inferred through electrospray mass spectrometry and cyclic voltammetry, and fluorescence properties were studied and Hirshfeld surface analyses were also conducted. [ABSTRACT FROM AUTHOR]

A series of Au catalysts supported on Cu–Al composite oxides were prepared and applied for the selective catalytic oxidation of glycerol to 1,3-dihydroxyacetone (DHA) in base-free conditions. The optimal Au/CuAlO-3 catalyst (the molar ratio of Cu/Al was 5 : 1) exhibited the best performance, and reached the glycerol conditions of 76.7% and DHA selectivity of 97.3% under the optimized reaction conditions. The high catalytic activity of the Au/CuAlO-3 catalyst correlated to the large concentration of surface-active oxygen species, the low reduction temperature of the support, the small size of Au nanoparticles (NPs) and the interactions between Au NPs and the support. This work demonstrates that Cu–Al composite oxides are promising supports for selective catalytic oxidation of glycerol to DHA, and may offer guidelines for designing efficient support for the selective conversion of glycerol to other high value-added products. [ABSTRACT FROM AUTHOR]

One homo-trinuclear 3d and five novel windmill-type hetero-pentanuclear 3d-4f complexes [Zn3(L)(OAc)2(H2O)]·CH2Cl2 (1), [Zn4(L)2Sm(NO3)2(EtOH)2]NO3·H2O·2CHCl3 (2), [Zn4(L)2Eu(NO3)2(EtOH)2]NO3·C2H5OH·2CHCl3 (3), [Zn4(L)2Gd(NO3)2(EtOH)2]NO3·C2H5OH·2CHCl3 (4), [Zn4(L)2Tb(NO3)2(EtOH)2]NO3·C2H5OH (5) and [Zn4(L)2Dy(NO3)2(EtOH)2]NO3·C2H5OH·2CHCl3 (6) were synthesized by the reactions of a new bis(Salamo)-based tetraoxime ligand (H4L) with Zn(OAc)2·2H2O and Ln(NO3)3·6H2O (Ln = Sm, Eu, Gd, Tb and Dy), respectively. The structures of complexes 1–6 were characterized via elemental analyses, FT-IR spectroscopy, UV-Vis spectroscopy and single crystal X-ray crystallography, and their fluorescence properties, catalytic activities and Hirshfeld surface analyses were studied. [ABSTRACT FROM AUTHOR]

Four hetero-bimetallic [ZnIILnIII] complexes with the general formula [Zn(L)(OAc)Ln(NO3)2] (Ln = Sm, Eu, Tb and Dy) were synthesized by the Salamo-type ligand H2L (6,6′-diethoxy-2,2′-[1,2-ethylenedioxybis(nitrilomethylidyne)]diphenol) with Zn(OAc)2·2H2O and Ln(NO3)3·6H2O (Ln = Sm, Eu, Tb and Dy), respectively. X-ray crystal diffraction analyses revealed that all the Zn(ii) atoms were penta-coordinated, adopting distorted square pyramidal geometries, and the Ln(iii) atoms were nona-coordinated, forming distorted tricapped trigonal prism geometries. In addition, three-dimensional supramolecular structures were assembled through intermolecular hydrogen-bond interactions. In the [ZnIILnIII] complexes, only [Zn(L)(OAc)Sm(NO3)2] showed obvious orange-red light emission under UV light due to the characteristic f–f transitions of Sm3+ ions, which meant that the ligand H2L could transfer energy from its excited state to the lowest excited state of the Sm3+ ion effectively. A decrease in the χMT value illustrated weak antiferromagnetic interaction exciting in the [Zn(L)(OAc)Tb(NO3)2] and [Zn(L)(OAc)Dy(NO3)2] complexes. [ABSTRACT FROM AUTHOR]

Three heterocyclic azo dyes of azotriazolyl-2,7-dihydroxynaphthalene (H3AD), azotetrazolyl-2-naphthol (H2ATN) and azotetrazolyl-2,7-dihydroxynaphthalene (H3ATD) have been synthesized and characterized by IR, Raman spectra, 1H, 13C NMR and X-ray single-crystal diffraction techniques and their azo–hydrazone tautomerism has been achieved by pH control and coordination-coupled proton transfer. UV-vis spectra have been used to monitor the pH-titration and metal-ion complex experiments for three solutions of H3AD, H2ATN and H3ATD and the analysis of their spectral data has provided a clear proof that the hydrazone form is the dominant tautomer in acidic and neutral solutions, while the azo form is the dominant one in alkaline solutions. Crystallographic data demonstrate that the neutral dyes exist as hydrazone tautomers but are changed to azo tautomers when they coordinate to metal ions. The time-dependent density functional theory (TD-DFT) calculations are used to demonstrate the UV-vis spectroscopic properties. [ABSTRACT FROM AUTHOR]

Through the self-assembly of a Salamo-type ligand H2L (H2L = 1,2-bis(3-methoxysalicylideneaminooxy)ethane) with Ni(OAc)2·4H2O, Ln(NO3)3·6H2O (Ln(iii) = La(iii), Gd(iii), Tb(iii) and Dy(iii)) and Py (Py = pyridine) or 4,4′-bipy (4,4′-bipy = 4,4′-bipyridine) or H2bdc (H2bdc = terephthalic acid), nine new Ni(ii)–Ln(iii) heterometallic complexes [Ni(L)La(OAc)(NO3)2(Py)(CH3OH)]·CH3OH (1), [Ni(L)Dy(OAc)(NO3)2(Py)] (2), 1∞[Ni(L)La(NO3)3(4,4′-bipy)(CH3OH)] (3), 1∞[Ni(L)Tb(NO3)3(4,4′-bipy)] (4), [Ni(L)Dy(OAc)(NO3)2(4,4′-bipy)] (5), [{Ni(L)Ln(NO3)2(DMF)(CH3OH)}2(bdc)] (Ln = La (6) and Gd (7)) and [{Ni(L)Ln(NO3)2(DMF)}2(bdc)] (Ln = Tb (8) and Dy (9)) were obtained, respectively. The acetato ligand bridges the Ni(ii) and Ln(iii) (Ln = La (1) and Dy (2)) atoms in a μ2 fashion and the Py coordinates to the apical position by a nitrogen atom in the heterobimetallic complexes 1 and 2. Complexes 3 and 4 are 1D coordination polymers constructed from heterobimetallic [Ni(L)Ln] (Ln = La (3) and Tb (4)) units which are connected by the exo-dentate ligand 4,4′-bipy bearing nitrogen-donor atoms, but complex 5 is a heterobimetallic Ni(ii)–Dy(iii) complex which is prepared under the same reaction conditions as complexes 3 and 4. Four heterotetranuclear dimers were constructed from heterobimetallic [Ni(L)Ln] (Ln = La (6), Gd (7)), Tb (8) and Dy (9) units which are connected by the exo-dentate H2bdc ligand with oxygen-donor atoms. Magnetic measurements were performed on the Gd(iii), Tb(iii) and Dy(iii) complexes. [ABSTRACT FROM AUTHOR]

A novel approach for the direct synthesis of a 1,2,4-triazine core starting from eight azo conjugated aromatic compounds, 5-azo-(1,2,4-triazolyl) salicylic acid, 5-azo-(3-methyl-1,2,4-triazolyl) salicylic acid, 5-azo-(3-carboxyl-1,2,4-triazolyl) salicylic acid, 5-azo-(1,2-pyrazolyl) salicylic acid, 4-azo-(1,2,4-triazolyl) phenol, 4-azo-(3-carboxyl-1,2,4-triazolyl) phenol, 4-azo-(1,2-pyrazolyl) phenol, and 5-azo-(1,2,4-triazolyl) acetylsalicylic acid, via transition or lanthanide metal catalyzed intramolecular C–H/N–H functionalization and C–N bond formation has been developed under one-step hydrothermal synthetic conditions. [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]