Scalable Synthesis and Supramolecular Assembly of trans-A2B2 Porphyrins with Pendant Carboxylic Functional Groups

Bharat Kumar Tripuramallu*, Ramesh Palakuri, Hatem M. Titi, Israel Goldberg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


This article deals with facile synthesis of A2B2 porphyrins bearing carboxylate groups at 5,15- positions and different functional groups at 10,20- positions viz. 4-iodophenyl (a), 4-tert-butylphenyl (b), 3,5-dimethoxyphenyl (c) 3-carboxyphenyl (d), 2-thienyl (e) 4-nitrophenyl (f), 4-methoxy-2,3,5,6-tetrafluorophenyl (g) and 2-pyrenyl (h) as single major component in scalable yields. It relates also to the supramolecular assembly modes of these species. The use of stoichiometric amounts of trifluoroacetic acid in condensation of 5-(4-methoxycarbonylphenyl)dipyrromethane and different aldehydes led to the formation of trans-porphyrins as di-esters (1 a-1 h). These were transformed by hydrolysis to the corresponding di-acids (2 a-2 h). (1 a-1 h) and (2 a-2 h) were then core-metalated to afford the corresponding metalloporphyrin species (3 a-3 h) and (4 a-4 h). The absorption and emission spectra of the free base (2 a-2 h) and metallated porphyrins (4 a-4 h) were found greatly influenced by the substituents at 10,20-positions. SEM studies of solids deposited on surfaces from solution exhibited hydrogen-bonded block-shaped structures of 2 e and fibrous sheets of 2 f. Co-crystallization of 2 a and 2 g with 4,4′-bipyridyl yielded hetero-molecular structures stabilized by both hydrogen O−H⋅⋅⋅N, and halogen N⋅⋅⋅I bonds in 2 a, and by O−H⋅⋅⋅N hydrogen bonds and C−F⋅⋅⋅π interactions in 2 g.

Original languageEnglish
Pages (from-to)885-893
Number of pages9
Issue number3
StatePublished - 23 Jan 2017


  • Crystal structure
  • Efficient synthesis
  • Optical properties
  • Supramolecular chemistry
  • trans-AB-porphyrins


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