López Arbeloa F, Bañuelos Prieto J, Martínez Martínez V, Arbeloa López T, López Arbeloa I
Departamento de Química Física, Universidad del Pais Vasco-EHU, Apartado 644, 48080 Bilbao, Spain.
Chemphyschem. 2004 Nov 12;5(11):1762-71. doi: 10.1002/cphc.200400242.
Absorption and fluorescence (steady-state and time-correlated) techniques are used to study the photophysical characteristics of the pyrromethene 650 (PM650) dye. The presence of the cyano group at the 8 position considerably shifts the absorption and fluorescence bands to lower energies with respect to other related pyrromethene dyes; this is attributed to the strong electron-acceptor character of the cyano group, as is theoretically confirmed by quantum mechanical methods. The fluorescence properties of PM650 are intensively solvent-dependent. The fluorescence band is shifted to lower energies in polar/protic solutions, and the evolution of the corresponding wavelength with the solvent is analysed by a multicomponent linear regression. The fluorescence quantum yield and the lifetime strongly decrease in polar/protic solvents, which can be ascribed to an extra nonradiative deactivation, via an intramolecular charge-transfer state (ICT state), favoured in polar media.
采用吸收光谱和荧光光谱技术（稳态和时间相关）研究了吡咯甲川650（PM650）染料的光物理特性。相对于其他相关的吡咯甲川染料，8位氰基的存在使吸收带和荧光带显著向低能量方向移动；这归因于氰基的强电子受体特性，量子力学方法从理论上证实了这一点。PM650的荧光性质强烈依赖于溶剂。在极性/质子性溶液中，荧光带向低能量方向移动，并通过多组分线性回归分析相应波长随溶剂的变化。在极性/质子性溶剂中，荧光量子产率和寿命大幅降低，这可归因于通过分子内电荷转移态（ICT态）的额外非辐射失活，而这种失活在极性介质中更为有利。
