Synthesis, DNA-binding and DNA-mediated luminescence quenching of Ru(II) polypyridine complexes

Two new polypyridyl ligands containing substituent Br at different positions in the phenyl ring, OBIP {OBIP = 2-(2-bromophenyl)imidazo[4,5-f]-1,10-phenanthroline}, PBIP {PBIP = 2-(4-bromophenyl)imidazo[4,5-f]-1,10-phenanthroline} and their Ru(II) complexes, [Ru(dmp)2(OBIP)]2+1 and [Ru(dmp)2(PBIP)]2+2
(dmp = 2,9-dimethyl-1,10-phenanthroline), have been synthesized and characterized. The binding of the two complexes to calf thymus DNA (CT DNA) has been investigated by spectrophotometric methods, viscosity measurements, as well as equilibrium dialysis and circular dichroism spectroscopy. Theoretical calculations for the two complexes were also carried out applying the density functional theory (DFT) method. The structure of complex 1 has been determined by single-crystal X-ray diffraction techniques. The imidazo[4,5-f]-1,10-phenanthroline moiety is not coplanar with the 2-bromophenyl ring, having a dihedral angle of 48.6° in the OBIP ligand. The twisted conformation has been further confirmed by theoretical calculations, in which this dihedral angle is 48.2°. The theoretical calculations also suggest that the PBIP ligand in complex 2 is essentially planar (dihedral angle is 0.4°). The experimental results show that while complex 1 binds to CT DNA via a semi-intercalative mode, complex 2 strongly binds to CT DNA through intercalation. Complex 2 is thus a much better candidate as an enantioselective binder to CT DNA than complex 1. Some experimental regularities or trends have been reasonably explained by the theoretical results. These suggest that the planarity of the intercalated ligand has significant effects on the spectral properties and the DNA-binding behavior of the complexes, and that the DFT method can be used effectively to explain and predict some regularities or trends in the interaction of polypyridyl Ru(II) complexes with DNA.

Effects of ligand planarity on the interaction of polypyridyl Ru(II) complexes with DNA

Polypyridyl ruthenium(II) complexes containing intramolecular hydrogen-bond ligand: syntheses, characterization, and DNA-binding properties

Twelve structurally diverse complexes, [Pb2(pzp)2(adip)(NO3)2] 1, [Pb(pzp)(glu)] 2, [Pb(pzp)(chdc)]·[Pb(pzp)(chdc)]·pzp·H2O 3, [Pb2(ndc)2(pzp)2(H2O)]·0.5H2O 4, [Pb(pzp)(1,3-bdc)(H2O)0.5]·H2O 5, [Pb(pzp)(1,2-bdc)]·H2O 6, [Pb2(ptc)2(adip)(NO3)2] 7, [Pb(ptc)(glu)] 8, [Pb(ptc)(chdc)] 9, [Pb(ptc)(dpdc)]2 10, [Pb(ptc)(1,3-bdc)]·2.5H2O 11, and [Pb(ptc)(1,4-bdc)]·0.75H2O 12, where H2adip = adipic acid, H2glu = glutaric acid, H2chdc = 1,4-cyclohexanedicarboxylic acid, H2ndc = 1,4-naphthalenedicarboxylic acid, 1,4-H2bdc = benzene-1,4-dicarboxylic acid, H2dpdc = 2,2′-diphenyldicarboxylic acid, 1,3-H2bdc = benzene-1,3-dicarboxylic acid, 1,2-H2bdc = benzene-1,2-dicarboxylic acid, pzp = pyrazino[2,3-f][1,10]phenanthroline, and ptc = 2-phenyl-1H-1,3,7,8,-tetraaza-cyclopenta[l]-phenanthrene, have been hydrothermally synthesized. Compounds 7 and 10 possess dinuclear structures, which are further extended by π−π interactions to form supramolecular layers and chains, respectively. 1−6, 8−9, and 11−12 feature chain structure...

A Series of Lead(II) Complexes with π−π Stackings: Structural Diversities by Varying the Ligands

A series of new metal-organic coordination complexes, [Co2(HBTC)2(Pyphen)2(H2O)4]·4H2O (1), [Mn(HBTC)(Pyphen)(H2O)] (2), [Cd2(OH)(BTC)(Pyphen)2]·H2O (3), [Cu2(OH)(BTC)(Pyphen)] (4), and [Zn2(OH)(BTC)(Pyphen)] (5) were prepared through hydrothermal reactions of pyrazino[2,3-f][1,10]-phenanthroline (Pyphen) and 1,3,5-benzenetricarboxylic acid (H3BTC) with different metal salts. All these compounds were structurally determined by X-ray single-crystal diffraction. In the dinuclear Co(II) compound (1) π–π interactions exist between Pyphen and HBTC2− ligands, resulting in interesting 2D supramolecular layers. For complex (2), the Mn(II) centers are linked by HBTC2− ligands to form a 2D (4,4) coordination layer, and these layers are interdigitated in pairs. Polymer (3) also possesses a 2D network structure composed of the tetrametallic clusters [Cd4(µ2-OH)2], which is extended to 3D arrays through the π–π interactions between Pyphen ligands. The isostructural coordination polymers (4) and (5) show the same 3D framework structure. Solid-state luminescent spectra of the Cd(II) and Zn(II) complexes indicate intense fluorescent emissions.

Syntheses, structures and photoluminescence of a series of metal-organic complexes with 1,3,5-benzenetricarboxylate and pyrazino[2,3-f][1,10]-phenanthroline ligands

Liang-Nian Ji

Papers

Synthesis, characterization and luminiscent DNA-binding study of a series of ruthenium complexes containing 2-arylimidazo[f]1,10-phenanthroline

Syntheses, crystal structures and spectroscopic characterization of [Co(phen)2(gly)]Cl2.4H2O and [Co(phen)2(H2O)2](NO3)3.2H2O