Conformational features of meso-tetrathienylporphyrins and photosensitising properties of their β-1-acetyl-2-oxopropyl derivatives

• Published in: Journal of molecular structure Vol. 1094; pp. 73 - 82
• Main Authors: Prasath, Rangaraj, Bhavana, Purushothaman
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.08.2015
• Subjects: Conformation; Extended conjugation; Nitration; Nitrothienylporphyrin; Photocatalyst; Redox; Nitrothienylporphyrin; Redox; Nitration; Extended conjugation; Photocatalyst; Conformation
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2015.04.006

[Display omitted] •Role of conformation in further reactions of porphyrins.•Role of electronic effects of substituents in further reactions of porphyrins.•Photosensitising properties of thienylporphyrins. The difference in the site of electrophilic nitration of meso-tetra-thien-2-yl- and thien-3-yl-porphyrins is explained based on the difference in extended conjugation between porphyrin core and meso-thienyl rings. The significance of resonance in dictating the site of substitution is also explained based on the behavior of tetrakis(5-bromothien-2-yl)porphyrin toward electrophilic nitration. Three new β-1-acetyl-2-oxopropyl-substituted porphyrins are synthesized by Michael addition of acetylacetone group on pyrrole β-nitroporphyrins. The photosensitizing properties of these porphyrins is investigated using porphyrin–TiO2 composites in the degradation of 4-nitrophenol. The results showed the importance of the effect of the position of sulfur on the thienyl ring and the orientation of meso-thienyl groups with the central macrocyclic ring of porphyrins in deciding its efficiency as photosensitiser.