Synthesis and characterization of rhenium(I) complexes based on O, N, N coordinating ligands: DFT/TDDFT studies on the electronic structures and spectral properties

Synthesis, crystal structure and photophysical properties of chlorido-[(E)-3-hy-droxy-2-methyl-6-(quinolin-8-yldiazen-yl)phenolato]copper(II) monohydrate

The reaction between copper(II) chloride dihydrate and the (E)-2-methyl-4-(quinolin-8-yldiazen-yl)benzene-1,3-diol ligand in aceto-nitrile leads to the formation of the title compound, [Cu(C16H12N3O2)Cl]·H2O. The ligand is deprotonated and coordinates with three donor atoms (tridentate) to the CuII ion. Individual mol-ecules of the CuII complex are connected by chloride bridges, forming a one-dimensional coordination polymer. No photoisomerization to the cis isomer of the azo ligand was observed upon irradiation with UV light.

Computational Design of Rhenium(I) Carbonyl Complexes for Anticancer Photodynamic Therapy

New Re(I) carbonyl complexes are proposed as candidates for photodynamic therapy after investigating the effects of the pyridocarbazole-type ligand conjugation, addition of substituents to this ligand, and replacement of one CO by phosphines in [Re(pyridocarbazole)(CO)3(pyridine)] complexes by means of the density functional theory (DFT) and time-dependent DFT. We have found, first, that increasing the conjugation in the bidentate ligand reduces the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gap of the complex, so its absorption wavelength red-shifts. When the enlargement of this ligand is carried out by merging the electron-withdrawing 1H-pyrrole-2,5-dione heterocycle, it enhances even more the stabilization of the LUMO due to its electron-acceptor character. Second, the analysis of the shape and composition of the orbitals involved in the band of interest indicates which substituents of the bidentate ligand and which positions are optimal for reducing the HOMO-LUMO energy gap. The introduction of electron-withdrawing substituents into the pyridine ring of the pyridocarbazole ligand mainly stabilizes the LUMO, whereas the HOMO energy increases primarily when electron-donating substituents are introduced into its indole moiety. Each type of substituents results in a bathochromic shift of the lowest-lying absorption band, which is even larger if they are combined in the same complex. Finally, the removal of the π-backbonding interaction between Re and the CO trans to the monodentate pyridine when it is replaced by phosphines PMe3, 1,4-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA), and 1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane (CAP) causes another extra bathochromic shift due to the destabilization of the HOMO, which is low with DAPTA, moderate with PMe3, but especially large with CAP. Through the combination of the PMe3 or CAP ligands with adequate electron-withdrawing and/or electron-donating substituents at the pyridocarbazole ligand, we have found several complexes with significant absorption at the therapeutic window. In addition, according to our results on the singlet-triplet energy gap, all of them should be able to produce cytotoxic singlet oxygen.

Experimental and theoretical investigation of a metalloreceptor bearing a [Re(CO)3]+ core incorporating a multifunctional ligand: selective reactivity towards Zn2+ and CN− ions

Novel Re(i) complex containing multifunctional ligand HL shows selective reactivity towards Zn²⁺ and CN⁻.

Theoretical study of the cis–trans isomerization mechanism of a pendant metal-bound azobenzene

Theoretical study of the cis–trans isomerization mechanism of azobenzene substituents in rhenium complexes.