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A series of symmetrical and unsymmetrical phenylene-vinylene(PV)based chromophores with the molecular configuration of donor-π-donor(D-π-D)were prepared and characterized.Iodine was first introduced into the-conjugation backbone of the PV based chromophores in order to study the heavy atom effect on their linear absorption,two-photon absorption(TPA)properties,as well as singlet oxygen generation properties.TPA cross-sections of these chromophores were investigated by using the two-photon excited fluorescence method.The unsymmetrical chromophores were found to have larger TPA cross-section values compared to their symmetrical counterparts.For one of the unsymmetrical chromophores with the iodine incorporation,a large TPA cross section value with quenched emission was found.The decreased fluorescence quantum yield of a molecule can be ascribed to the increased intersystem crossing,which is favorable for enhancing the singlet oxygen generation.Therefore,the unsymmetrical PV based chromophores with heavy atom incorporation are promising singlet oxygen sensitizers for the photodynamic therapy application.
A series of symmetrical and unsymmetrical phenylene-vinylene (PV) based chromophores with the molecular configuration of donor-π-donor (D-π-D) were prepared and characterized. Iodine was first introduced into the-conjugation backbone of the PV based chromophores in order to study the heavy atom effect on their linear absorption, two-photon absorption (TPA) properties, as well as singlet oxygen generation properties. TPA cross-sections of these chromophores were investigated by using the two-photon excited fluorescence method. unsymmetrical chromophores were found to have larger cross-section value compared to their symmetrical counterparts. For one of the unsymmetrical chromophores with the iodine incorporation, a large TPA cross section value with quenched emission was found. The decreased fluorescence quantum yield of a molecule can be ascribed to the increased intersystem crossing, which is favorable for enhancing the singlet oxygen generation. agofore the unsymmetrical PV based chromo phores with heavy atom incorporation are promising singlet oxygen sensitizers for the photodynamic therapy application.