Synthesis, structural investigation and kinetic studies of uranyl(VI) unsymmetrical Schiff base complexes

Comparing coordination uranyl(vi) complexes with 2-(1H-imidazo[4,5-b]phenazin-2-yl)phenol and derivatives

Four derivatives of 2-(1H-imidazo[4,5-b]phenazin-2-yl)phenol have been synthesized and characterized structurally using X-ray crystallography. Coordination complexes with uranyl (UO₂²⁺) and copper (Cu²⁺) were prepared and absorption/emission spectra detailed. We observed increased fluorescence upon uranyl binding, in stark contrast to rapid quenching observed with the addition of copper. These phenomena have been further examined by DFT computational methods.

Synthesis, Structural Investigations, Molecular Docking, and Anticancer Activity of Some Novel Schiff Bases and Their Uranyl Complexes

Three novel 2-aminopyrazine Schiff bases derived from salicylaldehyde derivatives and their uranyl complexes were synthesized and characterized by elemental analysis, UV-vis, FTIR, molar conductance, and thermal gravimetric analysis (TGA). The proposed structures were optimized using density functional theory (DFT/B3LYP) and 6-311G ∗(d,p) basis sets. All uranyl complexes are soluble in DMSO and have low molar conductance, which indicates that all the complexes are nonelectrolytes. The DNA binding of those Schiff bases and their uranyl complexes was studied using UV-vis spectroscopy, and screening of their ability to bind to calf thymus DNA (CT-DNA) showed that the complexes interact with CT-DNA through an intercalation mode, for which the K_b values ranged from 1 × 10⁶ to 3.33 × 10⁵ M^-1. The anticancer activities of the Schiff base ligands and their uranyl complexes against two ovarian (Ovcar-3) and melanoma cell lines (M14) were investigated, and the results indicated that uranyl complexes exhibit better results than the Schiff base ligands. Molecular docking identified the distance, energy account, type, and position of links contributing to the interactions between these complexes and two different cancer proteins (3W2S and 2OPZ).

A Diuranyl(VI) Complex and Its Application in Electrocatalytic and Photocatalytic Hydrogen Evolution from Neutral Aqueous Medium

The reaction of equimolar amounts of UO₂(OAc)₂·2H₂O, 2,6-diformyl-4-methylphenol, and N-(hydroxyethyl)ethylenediamine in methanol affords a dinuclear trans-uranyl(VI) complex of the molecular formula [(UO₂)₂(μ-L)₂] (L^2- = 2-formyl-4-methyl-6-((2-(2-oxidoethylamino)ethylimino)methyl)phenolate) in 65% yield. Detailed structural elucidation of the complex was performed by using single-crystal X-ray crystallographic and spectroscopic studies. In [(UO₂)₂(μ-L)₂], the metal centers are in edge-shared pentagonal-bipyramidal N₂O₅ coordination spheres assembled by the two meridional ONNO-donor bridging L^2- and two pairs of mutually trans oriented oxo groups. The complex is redox active and displays two successive metal-centered one-electron reductions at E_pc = -0.71 and -1.03 V in N,N-dimethylformamide solution. The redox-active complex was used as a heterogeneous catalyst for electrochemical hydrogen evolution from aqueous medium at pH 7 with a turnover frequency (TOF) of 384 h^-1 and a Tafel slope of 274 mV dec^-1. The Faradaic efficiency of [(UO₂)₂(μ-L)₂] was found to be 84%. Beyond the electrocatalytic response, the [(UO₂)₂(μ-L)₂]-TiO₂-N719 composite also exhibited significant heterogeneous photocatalytic hydrogen evolution activity in neutral aqueous medium under visible light and provided a yield of 3439 μmol g_cat^-1 of H₂ in 4 h with a TOF of 172 h^-1 and apparent quantum yield (AQY) of 7.6%.

Dihydroxo-bridged diuranyl(vi) complexes with 2-((2-(6-chloropyridazin-3-yl)hydrazono)methyl)-4-R-phenols: structural insights and visible light driven photocatalytic activities

Complexes of the {(UO₂)₂(μ-OH)₂}²⁺ core with N,N,O-donor 2-((2-(6-chloropyridazin-3-yl)hydrazono)methyl)-4-R-phenolates and their visible light-induced photocatalytic organic dye degradation abilities are reported.