From model compounds to protein binding: syntheses, characterizations and fluorescence studies of [Ru^II(bipy)(terpy)L]²⁺complexes (bipy = 2,2′-bipyridine; terpy = 2,2′:6′,2″-terpyridine; L = imidazole, pyrazole and derivatives, cytochrome c)

Abstract

Compounds [RuII(bipy)(terpy)L](PF6)2 with bipy = 2,2'-bipyridine, terpy = 2,2':6',2"-terpyridine, L = H2O, imidazole (imi), 4-methylimidazole, 2-methylimidazole, benzimidazole, 4,5-diphenylimidazole, indazole, pyrazole, 3-methylpyrazole have been synthesized and characterized by 1H NMR, ESI-MS and UV/Vis (in CH3CN and H2O). For L = H2O, imidazole, 4,5-diphenylimidazole and indazole the X-ray structures of the complexes have been determined with the crystal packing featuring only few intermolecular C-H...pi or pi-pi interactions due to the separating action of the PF6-anions. Complexes with L = imidazole and 4-methylimidazole exhibit a fluorescence emission with a maximum at 662 and 667 nm, respectively (lambdaexc= 475 nm, solvent CH3CN or H2O). The substitution of the aqua ligand in [Ru(bipy)(terpy)(H2O)]2+ in aqueous solution by imidazole to give [Ru(bipy)(terpy)(imi)]2+ is fastest at a pH of 8.5 (as followed by the increase in emission intensity). Coupling of the [Ru(bipy)(terpy)]2+ fragment to cytochrome c(Yeast iso-1) starting from the Ru-aqua complex was successful at 35 degrees C and pH 7.0 after 5 d under argon in the dark. The [Ru(bipy)(terpy)(cyt c)]-product was characterized by UV/Vis, emission and mass spectrometry. The location where the [Ru(bipy)(terpy)] complex was coupled to the protein was identified as His44 (corresponding to His39 in other numbering schemes) using digestion of the Ru-coupled protein by trypsin and analysis of the tryptic peptides by HPLC-high resolution MS.

Catalytic Photooxidation of Alcohols by an Unsymmetrical Tetra(pyridyl)pyrazine‐Bridged Dinuclear Ru Complex

“…Upon ligand substitution of Cl À by H 2 O (compound 3), this proton was shifted upfield to d % 9.52 ppm due to the larger diamagnetic anisotropy of the aqua ligand over the Cl À ion. [7,8] The same trend was observed for the dinuclear compounds 4 and 5.…”

Synthesis and structural characterization of some polypyridyl and polypyrazolyl Ru(II) complexes

“…The bond angles and distances are consistent with those of similar structures. 48,54 There are π-π stacking interactions between the bpe ligands of the adjacent complexes in the lattice of 14.…”

“…These complexes are new compounds, but they were prepared using reaction conditions that are very similar to those used for the closely related terpyridine complexes. 48,53,54 Reaction of ruthenium complex 12 with bpy in boiling aqueous EtOH in presence of LiCl afforded the crude complex 13. After purification on silica gel, the product was collected as its PF Single crystals suitable for X-ray were grown by vapour diffusion of diethyl ether into CH 3 CN solution of the complex.…”

Synthesis and Spectral Characterization of Hydrazone Schiff Bases Derived from 2,4-Dinitrophenylhydrazine. Crystal Structure of Salicylaldehyde-2,4-Dinitrophenylhydrazone

“…Centroid-centroid contacts are 4.35Å, interplanar distances 3.34 and 3.31Å, slip angles (angle between centroid-centroid vector and normal to plane) 50.2 and 49.6 • , and vertical displacements (between ring centroids) 2.79 and 2.82Å for the interactions of ring C11-C16 and C21-C26, respectively, with their symmetry related counterparts with operation x, 1±y, z [19 -21]. The program PLATON, which was used for calculating the supramolecular interactions, did neither indicate the presence of strong intermolecular C-H··· O hydrogen bonds [22,23] nor the existence of C-H··· π interactions [17,20,24,25]. Instead, a spacefilling presentation of adjacent molecules, shown in Fig.…”