Structurally Characterized Solvent-Induced Homotrinuclear Cobalt(II) N2O2-Donor Bisoxime-Type Complexes

Insight into Rare Structurally Characterized Homotrinuclear CuII Non-Symmetric Salamo-Based Complex

A rare homotrinuclear CuII salamo-based complex [Cu3(L)2(μ-OAc)2(H2O)2]·2CHCl3·5H2O was prepared through the reaction of a non-symmetric salamo-based ligand H2L and Cu(OAc)2·H2O, and validated by elemental analyses, UV-Visible absorption, fluorescence and infrared spectra, molecular simulation and single-crystal X-ray analysis techniques. It is shown that three CuII atoms and two wholly deprotonated ligand (L)2− moieties form together a trinuclear 3:2 (M:L) complex with two coordination water molecules and two bi-dentate briging μ-acetate groups (μ-OAc−). Besides, the Hirshfeld surface analysis of the CuII complex was investigated. Compared with other ligands, the fluorescent strength of the CuII complex was evidently lowered, showing that the CuII ions possess fluorescent quenching effect.

Synthesis and characterization for a highly selective bis(salamo)-based chemical sensor and imaging in living cell

A new sensor H₅L for continuous identification of Cu²⁺, Al³⁺ and lysine was synthesized by Schiff base reactions. The sensor could specifically recognized Cu²⁺ in the EtOH/H₂O (1:1 v/v) solution by UV-vis spectra, and the binding constant with Cu²⁺ can reach 10¹¹ M^-1, meanwhile, it was found by the naked-eye that the color of the solution was changed from colorless to yellow. The copper complex L-Cu²⁺ formed by the sensor H₅L and Cu²⁺ could further recognize Al³⁺ and lysine in the fluorescence spectra. The LOD values of the three objects were 2.67 × 10^-8, 1.96 × 10^-8 and 5.59 × 10^-9 M, respectively. In addition, fluorescence intracellular images of Al³⁺ and lysine were performed and obtained satisfactory results.

Highly efficient detection of Cu2+ and B4 O7 2- based on a recyclable asymmetric salamo-based probe in aqueous medium

An asymmetric salamo-based probe molecule (H₂ L) was synthesized and characterized structurally. When DMF/H₂ O (9:1) was used as the solvent, it was shown probe H₂ L has high sensitivity to Cu²⁺ . Using high-resolution mass spectrometry and theoretical calculation, it was found that probe H₂ L could form a more stable complex (1:1) with Cu²⁺ , the minimum limit of detection (LOD) of H₂ L for Cu²⁺ was calculated as 9.95 × 10^-8 M. In addition, probe H₂ L could also be used to identify B₄ O₇ ^2- under the same detection conditions and the minimum LOD of H₂ L for B₄ O₇ ^2- was calculated as 4.98 × 10^-7 M. At the same time, density functional theory theoretical calculation further proved the flexibility of probe H₂ L. Through the action of EDTA, probe H₂ L had a cyclic ability to recognize Cu²⁺ , and showed a better response in the physiological pH range; probe H₂ L had the characteristics of fast recognition speed and high efficiency. In addition, with probe H₂ L test paper for Cu²⁺ and B₄ O₇ ^2- , the effect was more obvious. Meanwhile, probe H₂ L can be used to quantitatively detect Cu²⁺ in water samples.

An Unsymmetric Salamo-like Chemosensor for Fuorescent Recognition of Zn2+

A new unsymmetric tetradentate salamo-like chemical sensor H₂L for fluorescent recognition of Zn²⁺ has been designed and synthesized. The sensor can recognize Zn²⁺ from other metal ions examined with selectivity, anti-interference, reliability and high sensitivity (LOD = 1.89 × 10^-6 M) in ethanol/H₂O solution. The results of UV-Vis and fluorescent spectra analyses, X-ray crystallographic study and DMol³ simulation and calculation (on Materials Studio) indicate that the chelation-enhanced fluorescence (CHEF) recognition mechanism of the sensor H₂L for Zn²⁺ is of its hindered PET process. The sensor H₂L for Zn²⁺ has excellent fluorescence characteristics and has potential application value in biological and environmental systems.

Unprecedented Dinuclear CuII N,O-Donor Complex: Synthesis, Structural Characterization, Fluorescence Property, and Hirshfeld Analysis

An unprecedented dinuclear CuII complex, [Cu2(L2)2], derived from a salamo-like chelating ligand H2L2, was produced by the cleavage of a newly synthesized, half-salamo-like ligand HL1 (2-[O-(1-ethyloxyamide)]oxime-3,5-dichloro-phenol). This was synthesized and characterized by elemental analyses, IR, UV–Vis and fluorescent spectra, single crystal X-ray diffraction analysis, and Hirshfeld surface analysis. X-ray crystallographic analysis indicated that the two CuII (Cu1 and Cu2) ions bore different (N2O3 and N2O2) coordination environments, the penta-coordinated Cu1 ion possessed a slightly twisted tetragonal pyramid geometry with the τ value τ = 0.004, and the tetra-coordinated Cu2 ion showed a slightly twisted square planar geometry. Interestingly, one oxime oxygen atom participated in the coordination reported previously. Moreover, an infinite two-dimensional layered supramolecular network was formed. Compared with HL1, the CuII complex possessed the characteristic of fluorescence quenching.

Fluorescence Properties and Density Functional Theory Calculation of a Structurally Characterized Heterotetranuclear [ZnII2–SmIII2] 4,4′-Bipy-Salamo-Constructed Complex

A new heterotetranuclear complex, [{Zn(L)Sm(NO3)3}2(4,4′-bipy)]·2CH3OH, was synthesized via an unsymmetrical single salamo-like ligand H2L: 6-methoxy-6′-ethoxy-2,2′-[ethylenedioxybis(azinomethyl)]diphenol, with Zn(OAc)2·2H2O, Sm(NO3)3·6H2O, and 4,4′-bipyridine by the one-pot method. The [ZnII2–SmIII2] complex was validated via elemental analysis, powder X-ray diffraction (PXRD) analysis, infrared spectroscopy, and ultraviolet–visible (UV–Vis) absorption spectroscopy. The X-ray single crystal diffraction analysis of the [ZnII2–SmIII2] complex was carried out via X-ray single-crystal crystallography. The crystal structure and supramolecular features were discussed. In addition, while studying the fluorescence properties of the [ZnII2–SmIII2] complex, the density functional theory (DFT) calculation of its structure was also performed.

A Newly Synthesized Heterobimetallic NiII-GdIII Salamo-BDC-Based Coordination Polymer: Structural Characterization, DFT Calculation, Fluorescent and Antibacterial Properties

A unprecedented hetero-bimetallic 3d-4f BDC-salamo-based coordination polymer, [(L)Ni(BDC)Gd(NO3)(DMF)] was prepared and validated via elemental analyses, IR and UV–Visible absorption spectra, DFT calculation, and X-ray crystallography. The six-coordinated Ni1 ion lies at the N2O2 donor site of the L2− moiety, and one DMF O atom and carboxylate O atom occupy, collectively, the axial positions, and form a twisted octahedron. The nine-coordinated Gd1 ion consists of three oxygen atoms (O12, O13, and O14) of two carboxylate groups, two oxygen atoms (O8 and O9) derived from one bidentate nitrate group, and an O2O2 coordination site (O1, O2, O6, and O5) of the L2− unit, forming a twisted three-capped triangular prism coordination geometry. Compared to the ligand (H2L), the fluorescence intensity decreases due to the coordination of metal ions. Meanwhile, the antibacterial activities are researched.

Four rare structurally characterized hetero-pentanuclear [Zn4Ln] bis(salamo)-type complexes: syntheses, crystal structures and spectroscopic properties

Four new hetero-pentanuclear 3d–4f complexes [Zn₄(L)₂La(NO₃)₂(OEt)(H₂O)] (1), [Zn₄(L)₂Ce(NO₃)₂(OMe)(MeOH)] (2), [Zn₄(L)₂Pr(NO₃)₂(OEt)(EtOH)] (3) and [Zn₄(L)₂Nd(NO₃)₂(OMe)(MeOH)] (4) were synthesized by the reactions of a newly synthesized octadentate bis(salamo)-based tetraoxime ligand (H₄L) with Zn(OAc)₂·2H₂O and Ln(NO₃)₃·6H₂O (Ln = La, Ce, Pr and Nd), respectively, and characterized via elemental analyses, FT-IR, UV-Vis spectroscopy and single crystal X-ray crystallography. The X-ray crystallographic investigation revealed that all Zn^II ions were located in N₂O₃ coordination spheres, and possessed a trigonal bipyramid coordination environment. The Ln^III ion lay in an O₈ coordination sphere, and adopted a distorted square antiprismatic coordination environment. Furthermore, supramolecular interactions and fluorescence properties were investigated.

Four new hetero-pentanuclear 3d–4f complexes 1–4 were synthesized and characterized. Supramolecular interactions and fluorescence properties of complexes 1–4 were investigated.

A highly sensitive and selective fluorescent "off-on-off" relay chemosensor based on a new bis(salamo)-type tetraoxime for detecting Zn2+ and CN. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2019;222:117209. [PMID: 31200268 DOI: 10.1016/j.saa.2019.117209]

A new naphthalenediol-based bis(salamo)-type fluorescent probe H₄L for Zn²⁺ and CN^- was reported. Probe H₄L showed a highly selective fluorescence enhancement toward Zn²⁺ over other metal ions including Cd²⁺, and obtained the L-Zn²⁺complex can only detect CN^- in various anions. Their recognition mechanisms were explained by Job plots, fluorescent and UV-vis titrations, and theoretical calculations. The L-Zn²⁺complex has been synthesized and structurally characterized using Hirshfeld surface analysis, elemental analyses, IR, UV-Vis and fluorescent spectra. Additionally, the relay probe with the wide adaptability of pH range and excellent stability showed highly selectivity for CN^- recognition.

An Unexpected Trinuclear Cobalt(II) Complex Based on a Half-Salamo-Like Ligand: Synthesis, Crystal Structure, Hirshfeld Surface Analysis, Antimicrobial and Fluorescent Properties

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.

A New Half-Salamo-Based Homo-Trinuclear Nickel(II) Complex: Crystal Structure, Hirshfeld Surface Analysis, and Fluorescence Properties

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.

A high-efficiency salamo-based copper(ii) complex double-channel fluorescent probe

In this paper, a salamo-based copper(ii) complex probe L-Cu²⁺ was synthesized, which combined with copper(ii) ions to form L-Cu²⁺ for the detection of S²⁻ and had a good fluorescence chemical response. Through spectral analysis, we found that S²⁻ could be identified with high sensitivity and selectivity in the presence of various anions and could be used for the detection of S²⁻ by the naked eye. With the addition of S²⁻, the solution color changed from colorless to bright yellow. UV absorption, fluorescence and other characterization methods were carried out, and the mechanism of action was determined. In addition, we performed a visual inspection of H₂S gas, and the probe L-Cu²⁺ could detect S²⁻ in the gas molecules, revealing its potential application value in biology and medicine.

A highly sensitive and selective salamo-based copper(ii) complex probe, L-Cu²⁺, was synthesized; it could be used for the detection of S²⁻ by UV and fluorescence spectroscopies. And it also could detect S²⁻ in gas molecules.

Unprecedented Hexanuclear Cobalt(II) Nonsymmetrical Salamo-Based Coordination Compound: Synthesis, Crystal Structure, and Photophysical Properties

A novel hexanuclear Co(II) coordination compound with a nonsymmetrical Salamo-type bisoxime ligandH4L, namely [{Co3(HL)(MeO)(MeOH)2(OAc)2}2]·2MeOH, was prepared and characterized by elemental analyses, UV–vis, IR and fluorescence spectra, and X-ray single-crystal diffraction analysis. Each Co(II) is hexacoordinated, and possesses a distorted CoO6 or CoO4N2 octahedrons. The Co(II) coordination compound possesses a self-assembled infinite 2D supramolecular structure with the help of the intermolecular C–H···O interactions. Meanwhile, the photophysical properties of the Co(II) coordination compound were studied.