Lilletvedt M, Tønnesen H H, Høgset A, Nardo L, Kristensen S
Division Pharmaceutics, Department of Pharmacy, School of Pharmacy, University of Oslo, Blindern, Oslo, Norway.
Pharmazie. 2010 Aug;65(8):588-95.
The spectroscopic properties of the patented photosensitizer meso-tetraphenyl chlorin disulphonate (TPCS2a), intended for use in photochemical internalization (PCI) technology, and the chemically related photosensitizer meso-tetraphenyl porphyrin disulphonate (TPPS2a) were characterized in 14 organic solvents of varying polarity and amphiprotic properties. Absorption spectra and fluorescence emission spectra were acquired, and Stokes' shifts and fluorescence quantum yields determined. These investigations yield information on the physicochemical interactions between the photosensitizers and their surroundings (i.e., the physiological environment in vivo or the vehicle in vitro), which is essential for the further development of drug formulations. TPPS2a and TPCS2a are rigid molecules, built up by conjugated ring systems which possess limited interactions with the surroundings in the ground state (So). Accordingly, only small spectral shifts were observed in the absorption spectra, as well as in the fluorescence emission spectra. TPPS2a is spatially more planar than TPCS2a, which is twisted as a result of reduction of a double bond in the core. However, the two compounds were quite similarly influenced by properties of the solvents, indicating that twisting has limited importance in the interactions of the two photosensitizers with their environment. Both compounds possess a high character of pi-pi* transition upon light exposure, supported by high molar absorption coefficients. The fluorescence quantum yields (phi(f)) were influenced by solvent properties to a larger extent than the spectral shifts. This might indicate that the reactivity of the first excited singlet state (S1*) significantly depends on the properties of the surroundings.
用于光化学内化（PCI）技术的专利光敏剂中-四苯基二磺酸氯卟啉（TPCS2a）以及化学相关的光敏剂中-四苯基二磺酸卟啉（TPPS2a）的光谱性质，在14种具有不同极性和两性性质的有机溶剂中进行了表征。获得了吸收光谱和荧光发射光谱，并测定了斯托克斯位移和荧光量子产率。这些研究提供了关于光敏剂与其周围环境（即体内的生理环境或体外的载体）之间物理化学相互作用的信息，这对于药物制剂的进一步开发至关重要。TPPS2a和TPCS2a是刚性分子，由共轭环系统构成，在基态（So）下与周围环境的相互作用有限。因此，在吸收光谱以及荧光发射光谱中仅观察到小的光谱位移。TPPS2a在空间上比TPCS2a更平面，TPCS2a由于核心中一个双键的还原而发生扭曲。然而，这两种化合物受溶剂性质的影响非常相似，表明扭曲在这两种光敏剂与它们环境的相互作用中重要性有限。两种化合物在光照下均具有较高的π-π跃迁特性，这由高摩尔吸收系数所支持。荧光量子产率（φf）受溶剂性质的影响程度大于光谱位移。这可能表明第一激发单重态（S1）的反应性显著取决于周围环境的性质。
