A new tetraiminodiphenol macrocyclic ligand and its two dicopper(II) complexes: Syntheses, crystal structures, electrochemistry and magnetochemistry

A very rare fluorescent chemosensor of zinc(II) exhibiting AIEE, ESIPT and TICT: Spectroscopic, crystallographic and theoretical exploration

The basic systems in this study are HL (1; 1:2 condensation product of 2,6-diformyl-4-ethylphenol and o-anisidine) and its ZnII and CdII complexes of composition [ZnII(LH)Cl2]·CH3OH (2) and [CdII(LH)Cl2] (3), all of which are synthesized and characterized by CHN elemental analyses, single crystal X-ray crystallography, powder X-ray diffraction (PXRD) and fourier transform infrared (FT-IR) spectrum. It has been established from the following experimental and theoretical studies that 1 is a fluorescent turn on sensor of ZnII ion and it exhibits all of excited state intramolecular proton transfer (ESIPT), photoinduced electron transfer (PET), twisted intramolecular charge transfer (TICT) and aggregation induced enhanced emission (AIEE): (i) Detailed absorption and emission (steady state / time resolved) studies in various single solvents, in solvent mixtures, with pH variation, with various single metal ions, with mixtures of metal ions, on varying temperature and on varying viscosity; (ii) dynamic light scattering (DLS) and scanning electron microscopy (SEM) in solvent mixtures; (iii) density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculations in ground and excites states of 1-3. It is shown that 1 can be efficaciously applied in inkless writing with the "write - erase - write" facility. The mechanisms/reasons of the observed properties have been addressed. The difference in fluorescence of ZnII and CdII complexes, unusual case of crystal structures of probe and complexes with ZnII and CdII, unusual features in the structures of 2 and 3 as well as a structure-property correlation have been discussed.

Designing and Exploration of the Biological Potentials of Novel Centrosymmetric Heteroleptic Copper(II) Carboxylates

Copper(II) complexes with a general formula [Cu2(3,4-F2C6H3CH2COO)4(L)2], where L = 2-methylpyridine (1) and 3-methylpyridine (2), are reported here. The FTIR spectra of the complexes confirmed the bridging bidentate coordination mode of the carboxylate ligand. The low (475 and 449 cm-1) and strong (727 & 725 cm-1) intensity bands in the FTIR spectra, due to Cu-N stretches and pyridyl ring vibrations, confirmed coordination of the 2-/3-methyl pyridine co-ligands in complexes 1 and 2, respectively. A binuclear paddlewheel structural arrangement with a square pyramidal geometry was confirmed for copper atoms in the complexes via single-crystal X-ray analysis. The DPPH, •OH radical, and α-amylase enzyme inhibition assays showed higher activities for the complexes than for the free ligand acid. The binding constant (Kb = 1.32 × 105 for 1 and 5.33 × 105 for 2) calculated via UV-VIS absorption measurements and docking scores (-6.59 for 1 and -7.43 for 2) calculated via molecular docking showed higher SS-DNA binding potential for 2 compared to 1. Viscosity measurement also reflected higher DNA binding ability for 2 than 1. Both complexes 1 and 2 (docking scores of -7.43 and -6.95, respectively) were found to be more active inhibitors than the free ligand acid (docking score of -5.5159) against the target α-amylase protein. This in silico study has shown that the herein reported compounds follow the rules of drug-likeness and exhibit good potential for bioavailability.

A metal complex based fluorescent chemodosimeter for selective detection of 2,4-dinitrophenol and picric acid in aqueous medium

The work in this report describes the syntheses, characterization, crystal structures, absorption and emission spectra and DFT calculations of three dizinc(II) compounds of composition [ZnII2L(μ1,1-N3)(N3)2] (1), [Zn2L'(2,4-dinitrophenolate)2] (2) and [Zn2L'(picrate)2]...

Syntheses, crystal structures and steady state and time-resolved fluorescence properties of a PET based macrocycle and its dinuclear ZnII/CdII/HgII complexes

The present report deals with solution spectroscopic (absorption and emission) and colorimetric studies of a Robson type tetraaminodiphenol macrocyclic ligand and its ZnII2, CdII2 and HgII2 compounds.