Synthesis, Crystal Structures and Photophysical Properties of Novel Tetranuclear Cadmium(II) Schiff-Base Complexes

Supramolecular clumps of μ2-1,3-acetate bridges of Cd(II)-Salen complex: Synthesis, spectroscopic characterization, crystal structure, DFT quantization's, and antifungal photodynamic therapy

The article divulges the crystal growth, synthesis, and X-ray structure characterization of one centrosymmetric cadmium complex, [Cd{CdL(μ2-1,3-acetate)}2] using Salen ligand (SL). The complex is further characterized using spectroscopic and analytical techniques, including DRS, SEM-EDX, PXRD, and ICP-MS. The crystallographic study showed that the complex has a monoclinic space P21/c. Addison parameters (Ʈ) show the hexagonal geometry of the central Cd(II) metal ion. Hirshfeld surface and 2-D fingerprint confirm supramolecular contacts despite weak C-H⋯O and C-H···π interactions. Energy frameworks, FMOs, global reactivity parameters, MEP, and energy bandgap explain the complex reactivity outlook. The complex inter- and intramolecular bonding interactions were explored through natural bond orbital (NBO), QTAIM, NCI-RDG, Electron Location Function (ELF), and Localized Orbital Locator (LOL) quantization methods. In addition, the complex and its synthetic components in vitro antibacterial efficacy were investigated using Gram-positive and Gram-negative microbial strains. SAR (structure-activity relationship) correlates with biological potency. Molecular docking assessed antimicrobial potency with proteins S. aureus (PDB ID: 1JIJ), C. albicans (PDB ID: 1M7A), E. coli (PDB ID: 1T9U), P. aeruginosa (PDB ID: 2UV0), and A. Niger (PDB ID: 3K4P). The findings are backed by the Protein-Ligand Interaction Profiler (PLIP). The antifungal potency and cell viability test of C. albicans were conducted using photodynamic therapy (APDT).

A Fluorescent Chemosensor Based on Schiff Base for the Determination of Zn2+, Cd2+and Hg2

Metal complexes were obtained by the reaction of zinc, cadmium and mercury(II) salts with Schiff base HL (N(salicylidene)benzylamine). HL was synthesized by the condensation reaction of benzylamine and 2-hydroxybenzaldehyde. The fluorescence properties of the Schiff base and its metal complexes were studied in ethanol-water solutions. HL was examined for its utility as a fuorescent chemosensor for the determination of Zn²⁺, Cd²⁺ and Hg²⁺ in aqueous samples. The HL chemosensor was found to be sensitive to Zn²⁺, Cd²⁺ and Hg²⁺ than some metal ions and its complexes emitted strong fluorescence at 452 nm for Zn²⁺ at 474 nm for Cd²⁺ and at 491 nm for Hg²⁺, respectively. It was determined that HL forms complexes with a ratio of 2:1 for Zn²⁺ and Hg²⁺ and with a ratio of 1:1 for Cd²⁺ by Job plots. For the detection of Zn²⁺, Cd²⁺ and Hg²⁺ in aqueous samples, pH, solvent type and ligand concentration were optimized for an analytical method based on HL chemosensor. HL gave a wide range of linearity with Zn²⁺, Hg²⁺ and Cd²⁺, the limit of detection was found to be 2.7 × 10^-7 M, 7.5 × 10^-7 M and 6.0 × 10^-7 M, respectively.

Manganese(II), lead(II) and cadmium(II) coordination complexes containing a tetrazole-based acylamide ligand: synthesis and the influence of the metal ions on the structures

Three new manganese(II), lead(II) and cadmium(II) coordination complexes have been prepared by reaction of N-(1H-tetrazol-5-yl)cinnamamide (HNTCA) with divalent metal salts (MnCl2, PbCl2 and CdCl2) in a mixed-solvent system, affording mononuclear to trinuclear structures namely, bis(methanol-κO)bis[5-(3-phenylprop-2-enamido)-1H-1,2,3,4-tetrazol-1-ido-κ2 N 1,O]manganese(II), [Mn(C10H8N5O)2(CH3OH)2], (1), bis[μ-5-(3-phenylprop-2-enamido)-1H-1,2,3,4-tetrazol-1-ido]-κ3 N 1,O:N 2;κ3 N 2:N 1,O-bis{aqua[5-(3-phenylprop-2-enamido)-1H-1,2,3,4-tetrazol-1-ido-κ2 N 1,O]lead(II)}, [Pb2(C10H8N5O)4(H2O)2], (2), and hexakis[μ2-5-(3-phenylprop-2-enamido)-1H-1,2,3,4-tetrazol-1-ido-κ3 N 1,O:N 2]tricadmium(II), [Cd3(C10H8N5O)6], (3). The structures of these three compounds reveal that the nature of the metal ions and the side groups of the organic building blocks have a significant effect on the structures of the coordination compounds formed. Intermolecular hydrogen bonds link the molecules into two-dimensional [complex (1)] and three-dimensional hydrogen-bonded networks. Complexes (2) and (3) show significant fluorescence, while complex (1) displays no fluorescence.

A two-dimensional CdII coordination polymer based on naphthalenediimide: synthesis, crystal structure and photochromic properties

Naphthalenediimides, a class of organic dyes with an expanded π-electron-deficient plane, have attracted considerable interest because of their photoinduced electron transfer from neutral organic moieties to stable anionic radicals. This makes them excellent candidates for organic linkers in the construction of photochromic coordination polymers. Such a photochromic two-dimensional coordination polymer has been prepared using N,N'-bis(pyridin-4-ylmethyl)naphthalene-1,8:4,5-bis(dicarboximide) (DPMNI). In crystallization tubes, upon slow diffusion of an MeOH solution of cadmium perchlorate into a CHCl₃ solution of DPMNI, the complex poly[[bis[μ₂-2,7-bis(pyridin-4-ylmethyl)benzo[imn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone-κ²N:N']bis(perchlorato-κO)cadmium(II)] chloroform tetrasolvate], {[Cd(C₂₆H₁₆N₄O₄)₂(ClO₄)₂]·4CHCl₃}_n, (I), was obtained. The asymmetric unit contains one Cd²⁺ cation, two DPMNI ligands, two coordinated ClO₄^- anions and four CHCl₃ solvent molecules. Each Cd²⁺ cation is interconnected by four DPMNI linkers to generate a neutral two-dimensional naphthalenediimide coordination network with all the ClO₄^- anions above or below this plane. Strong interlaminar anion-π interactions between the coordinated ClO₄^- anions and the imide rings of an adjacent layer lead to a three-dimensional supramolecular structure. Compound (I) exhibits reversible photochromic behaviour and photocontrolled tunable luminescence properties, which may originate from the photoinduced electron-transfer generation of radicals in the DPMNI ligand.

Different conjugated system Zn(ii) Schiff base complexes: supramolecular structure, luminescent properties, and applications in the PMMA-doped hybrid materials

Five Zn(ii) complexes with different conjugated systems were synthesized. Zn3 was incorporated into PMMA, creating a high performance material.

Luminescence properties of a Zn(ii) supramolecular framework: easily tunable optical properties by variation of the alkyl substitution of (E)-N-(pyridine-2-ylethylidyne)arylamine ligands

The easily tunable luminescence properties of Zn(ii) complexes based on the different alkyl substituents of the Schiff-base ligand have been studied in detail.

A three-dimensional cadmium(II) coordination polymer with unequal homochiral double-stranded concentric helical chains

A homochiral helical three-dimensional coordination polymer, poly[[(μ2-acetato-κ(3)O,O':O)(hydroxido-κO)(μ4-5-nicotinamido-1H-1,2,3,4-tetrazol-1-ido-κ(5)N(1),O:N(2):N(4):N(5))(μ3-5-nicotinamido-1H-1,2,3,4-tetrazol-1-ido-κ(4)N(1),O:N(2):N(4):N(5))dicadmium(II)] 0.75-hydrate], {[Cd2(C7H5N6O)2(CH3COO)(OH)]·0.75H2O}n, was synthesized by the reaction of cadmium acetate, N-(1H-tetrazol-5-yl)isonicotinamide (H-NTIA), ethanol and H2O under hydrothermal conditions. The asymmetric unit contains two crystallographically independent Cd(II) cations, two deprotonated 5-nicotinamido-1H-1,2,3,4-tetrazol-1-ide (NTIA(-)) ligands, one acetate anion, one hydroxide anion and three independent partially occupied water sites. The two Cd(II) cations, with six-coordinated octahedral and seven-coordinated pentagonal bipyramidal geometries are located on general sites. The tetrazole group of one symmetry-independent NTIA(-) ligand links one of the independent Cd(II) cations into 61 helical chains, while the other NTIA(-) ligand links the other independent Cd(II) cations into similar but unequal 61 helical chains. These chains, with a pitch of 24.937 (5) Å, intertwine into a double-stranded helix. Each of the double-stranded 61 helices is further connected to six adjacent helical chains through an acetate μ2-O atom and the tetrazole group of the NTIA(-) ligand into a three-dimensional framework. The helical channel is occupied by the isonicotinamide groups of NTIA(-) ligands and two helices are connected to each other through the pyridine N and carbonyl O atoms of isonicotinamide groups. In addition, N-H···O and O-H···N hydrogen bonds exist in the complex.