Tin Porphyrins with Germyl- and Silylalkynyl Substitution: Synthesis, Characterization, and Solar Cell Applications

Porphyrins, known for their extensive biological functions, have been adapted for diverse applications through modification of their substitution patterns and metal centers. This study focuses on synthesizing tin porphyrins with germyl- and silyl-alkenyl substituents, addressing gaps in structural characterization and solubility behavior. Additionally, their potential in bulk-heterojunction solar cells is investigated. The synthetic pathways for these porphyrins are established, and their structural properties are analyzed using single crystal X-ray diffraction. The solubility of the synthesized porphyrin (5) is compared with meso-tetraaryl and meso-tetraalkyl free-base porphyrins. Electrochemical properties are studied through cyclic voltammetry, and density functional theory (DFT) calculations provide insights into the highest occupied and lowest unoccupied molecular orbitals. Despite promising optical and electrochemical properties, the solar cell performance of the synthesized porphyrins remains moderate, highlighting the need for further functionalization to enhance the power conversion efficiency.