Triplet Thermal Relaxation Study as a Probe of Weak Interdimers of Porphyrin Derivatives

Abstract

This article deals with results concerning the study of interacting dyes which are able to create weak interdimers. Two groups of organic systems: phthalocyanines (di-ethanol-amine and di-octane-amine) and pyridyl porphyrins (zinc, copper, and free-base) covalently linked to polyethylene glycol (PEG) in water and organic solvents (dioxane, dimethylsulfoxide) were investigated. Absorption, fluorescence, and photoacoustics were used as experimental methods but particular attention was paid to light-induced optoacoustic spectroscopy to follow the dye's triplet population and triplet thermal relaxation to study intermolecular interactions. It has been shown that even the weak interactions of the organic dyes under study is not detectable by absorption and only slightly by fluorescence is it possible to follow interactions by complementary photothermal methods. The results obtained for selected phthalocyanines and covalent porphyrin-polymer samples evidently show that the lightinduced optoacoustic experiment is a perfect tool in the detection of weakly interacting aggregates.

The impact of solvents on the singlet and triplet states of selected fluorine corroles – absorption, fluorescence, and optoacoustic studies

“…Specific details of LIOAS apparatus have been described by other groups. 26,33,34 For LIOAS experiments, corrole dyes are dissolved in CL, TL, DMF, and DMSO respectively. Ferrocene (FC), purchased from Sigma-Aldrich, and Ni-substituted pheophytin a 35 were chosen as calorimetric references due to their suitable spectral properties for LIOAS experiments.…”