Synthesis of Conjugated Polymer Based in Zn(II) Porphyrin Bearing Terminal Alkynyl Groups as Photosensitizer

Abstract

5,10,15,20-tetrakis-[4-(ethynyl)phenyl]porphyrin (TEP) was synthesized from the condensation of 4-(ethynyl)benzaldehyde and pyrrole catalyzed by boron trifluoride diethyl etherate in dichloromethane (DCM). After oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and purification, TEP was obtained in 34% yield. This porphyrin was metaled with Zn(II) acetate in DCM/methanol to produce the complex ZnTEP in 98% yield. A homocoupling reaction of terminal alkynes of ZnTEP to diynes was used to synthesize conjugated polymer organogel (ZnTEPP). The reaction was co-catalyzed by PdCl2(PPh3)2 and CuI in tetrahydrofuran. The solvent was evaporated to obtain xerogel and the SEM images showed microporous structure. In addition, spectroscopic and photodynamic studies of ZnTEPP indicated that the porphyrin unit retains its properties as a photosensitizer. Thus, this polymer is an interesting material with potential applications in forming photoactive aseptic surfaces.