Linear and nonlinear optical properties of DNA binding chromophores

Licentiate thesis, 2011

Research presented in this thesis concerns the linear and nonlinear optical properties of DNA binding chromophores. DNA interacts with chromophores with various effects in humid poly-vinyl alcohol (PVA) polymer environment. A study on those DNA-dye and PVA-dye interactions is possible by using homologous set of dyes from cyanine family with increasing charge and thus DNA affinity. UV-vis spectroscopy shows that the PVA matrix destabilizes all three DNA-dye complexes compared to aqueous solution, but to a lesser degree as the dye charge increases. Chromophores with unique spectral and optical properties are water soluble ruthenium (II) complexes that are known to intercalate DNA. Remarkable multiphoton absorption properties have been discovered using nonlinear spectroscopy techniques. In particular, [(11,11’-bidppz)(phen)4Ru2]4+; complex was found to exhibit very strong two- and three-photon absorption properties which are an effect of complex extension due to the dimerization of monomer structures [Ru(phen)2dppz]2+. We propose that these substances could be a new generation of DNA binding nonlinear chromophores for wide applications in biology and material science.