Studies Of Ruthenium(II) Complexes In Optical Materials And DNA Molecular Recognition

A series of novel bridging ligands with as-triazine, A series of novel asymmetry tridentate ligands with as-triazole, and A series of novel tridentate ligands with imidazole have been designed and synthesized with 4,4'-bipyridyl or 1, 10-phenthroline. The structures and electronic properties of these ligands have been investigated in detail. Firstly, by use of these novel ligands, a series of dinuclear complexes [Ru₂(bpy)₄(BL)]⁴⁺, where bpy = 2,2'-bipyridine, BL = 2,2'-bis(1,2,4-triazin-3-yl)-4,4'-bipyridine(BTZ), 2,2'-bis(5,6-diphenyl-1,2,4-triazin-3-yl)-4,4'-bipyridine(BBTZ), 2,2'-bis(1,2,4-triazino[5,6-f]acenaphthylen-3-yl)-4,4'-bipyridine(BTZA), 2,2'-bis(1,2,4-triazino[5,6-f]phenanthren-3-yl)-4,4'-bipyridine (BTZP) have been synthesized, the [Ru₂(bpy)₄(BBTZ)]⁴⁺ have been resolved. Secondly, a series of ruthenium(II) asymnetry tridentate complexes [Ru(tpy)(L)]²⁺, where tpy = 2, 2':6'2''–terpyridyl, L = 2-(phenylimidazol-2-yl)-1,10-phenanthroline(PHPI), 2-(naphthalenylimidazol-2-yl)-1,10-phenanthroline(PHNI), 3-(1,10-phenanthrolin-2-yl)-1,2,4-triazole(PHT), 3-(1,10-phenanthrolin-2-yl)-5-methyl-1,2,4-triazole(PHMT) and the deprotonated complex of [Ru(tpy)(PHT)]²⁺ have been synthesized. The structures and photo-physical properties of these complexes have been investigated systematically with various methods including microanalyses, ES-MS, NMR, FT-IR, UV-Vise, electrochemistry, CD, and emission(77 K). It has been found that the bridging ligands with as-triazine is a good Ï€-acceptor, there are strong metal-metal coupling interaction and bigger Kcom in the dinuclear complexes. For all these complexes, no emission can be detected in room temperature. This is attributed to the intercomponent electron and energy transfer. As to [Ru(tpy)(L)]²⁺, it is due to the activated radiationless decay. DNA binding mechanisms of the complexes are observed by electronic absorption spectra, competitive binding, CD spectra, and viscosity measurements. It has been found that DNA binding mechanisms of these complexes are relevant to the structure of ligands and the shape of complexes. The electronic absorption spectra hypochromism at MLCT of the dinuclear complexes [Ru₂(bpy)₄(BL)]⁴⁺(BL = BTZ, BTZA, BTZP, BBTZ) is 8.7%, 19%, 16.3% and 33% in sequence, the binding constant is 7.5×10⁴ M^-1,4.8×10⁵ M^-1, 6.4×10⁵ M^-1 and 7.6×10⁵ M^-1. The larger the bridging ligands'plane, the stronger the hydrophobic effect of complexes, the stronger the complexes binding to calf thymus DNA. The binding constant of the Λ,Λ?[Ru2(bpy)4(BBTZ)]4+ is as 1.41 times as the ?,?? enantiomer , the binding constant of the rac-enantiomer is mean to the chiral enantiomer. while it does not show significant effect on DNA viscosity. Competitive binding experiments indicate that the dinuclear complexes could drive out the intercalator ethidium bromide from DNA. These experiments suggest the [Ru2(bpy)4(BL)]4+ should be bound to DNA by groove binder or partial intercalation. The dialysis experiments show that the [Ru2(bpy)4(BBTZ)]4+ is obvious enantioselectively binding to DNA, It shows that the Λ,Λ? enantiomer is stronger then the ?,??enantiomer binding to DNA. This is because the BBTZ's two phenyl of the Λ,Λ? enantiomer intercalates the major groove in a side-on mode where the metal-BBTZ axis lies along the long axis of the base pairs, while the ?,??enantiomer is sterically hinder in the same manner. The complex is a novel dinuclear chiral probe of DNA structure. The other dinuclear complexes is not enantioselectivyly binding to DNA. It can be controlled the modes of dinuclear complexes binding to DNA with briding ligands structure varietions. The electronic absorption spectra hypochromism at MLCT of the complexes [Ru(tpy)(L)]2+(L=PHPI, PHT, PHMT) is modest, [Ru(tpy)(PHNI)]2+ is larger(29%). Competitive binding experiments indicate that the complexes could drive out the intercalator ethidium bromide from DNA. The [Ru(tpy)(PHNI)]2+ decrease DNA viscosity significantly, while the others do not show significant effect on DNA viscosity. It is suggested that the [Ru(tpy)(PHNI)]2+ is partial intercalation and the others are groove binders. In addition, The complexes [Ru(PIP)2(L1)]2+(L1=phen, tatp, dppz, dppn), [Ru(L2)2(NOP)] (L2=phen, dmp, tatp, dppz, dppn), [Ru(dmp)2(L3)]2+(L3=PIP, ClP, HOP, MNP) and [Ru(L4)n (L5)3-n]2+(L4=bpy, L5=IP, PIP) with strong third order non-linear effect have been synthesized. The structures and properties of these complexes have been investigated systematically with various methods including microanalyses, ES-MS, NMR, FT-IR, UV-Vise, and cyclic voltammetry. Non-linear optical (NLO) properties (third order non-linear refractive index n2 and nonlinear absorption index α2) of the complexes were investigated by using Z-scan techniques in 540 nm. The effective third-order susceptibility χ(3) and the hyperpolarzability γof the comp-lexes were calculated out. All complexes exhibit both NLO absorption and self-defocusing. The results indicate that the profile of ligands, the substituent of the ligand have an effect on the NLO properties of the complexes. The complexes with pyrazine-like ligand have been found to be a kind of third nonlear optical materials with prospect due to good transparency and strong third order non-linear optical effect. The structure-property relationships have been discussed inpreliminary step, it gives good information for designs and syntheses of the complexes with strong third order non-linear optical effect.