Spectral and Spatial Characteristics of TPPS3 and TPPS₄ Aggregates

TPPS molecules, because of their unique properties, could be used in biomedicine and application as organic semiconductors for nanometer-scale photovoltaic cells, artificial light harvesting systems, nonlinear optic materials. However, some properties of these photosensitizers are not so well known which makes their application more complicated. In this work a thorough investigation was made to discover spectral and spatial characteristics of $5,10,15,20$-tetrakis(4sulfonatophenyl)porphyrin (TPPS4) and tris(4-sulfonatophenyl)-20-phenylporphyrin (TPPS3). The presence of sulfo groups changes spectral and spatial characteristics of the porphyrin. Our research investigated TPPS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> and TPPS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> solutions at different concentrations and pH levels, aggregation process and determined $\mathrm{pK}_{\mathrm{a}}$ value of these porphyrins.