Flexible tuning of unsaturated β-substituents on Zn porphyrins: A synthetic, spectroscopic and computational study

Journal Article


Abstract


  • A series of zinc porphyrins substituted at adjacent β-positions with a CN group and para-substituted ethenyl/ethynyl-phenyl group have been studied using electronic absorption spectroscopy, resonance Raman spectroscopy and DFT calculations. The oxidative nucleophilic substitution of hydrogen was utilized for the introduction of a cyano substituent on the porphyrin ring. This modification has a remarkable electronic effect on the ring. The resulting porphyrin cyanoaldehyde was further modified in Wittig condensations to give series of arylalkene- and arylalkyne-substituted derivatives. This substitution pattern caused significant redshifting and broadening of the B band, tuning from 433-446nm. Additionally the Q/B band intensity ratios show much higher values than observed for the parent porphyrin ZnTPP (0.20 vs. 0.03). Careful analysis of the electronic transitions using DFT and resonance Raman spectroscopy reveal that the substituent does not significantly perturb the electronic structure of the porphyrin core, which is still well described by Gouterman's four-orbital model. However, the substituents do play a role in elongating the conjugation length and this results in the observed spectral changes.

Publication Date


  • 2015

Citation


  • van der Salm, H., Wagner, P., Wagner, K., Officer, D. L., Wallace, G. G. & Gordon, K. C. (2015). Flexible tuning of unsaturated β-substituents on Zn porphyrins: A synthetic, spectroscopic and computational study. Chemistry: A European Journal, 21 (44), 15622-15632.

Scopus Eid


  • 2-s2.0-84945449686

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/1625

Has Global Citation Frequency


Number Of Pages


  • 10

Start Page


  • 15622

End Page


  • 15632

Volume


  • 21

Issue


  • 44

Place Of Publication


  • Germany

Abstract


  • A series of zinc porphyrins substituted at adjacent β-positions with a CN group and para-substituted ethenyl/ethynyl-phenyl group have been studied using electronic absorption spectroscopy, resonance Raman spectroscopy and DFT calculations. The oxidative nucleophilic substitution of hydrogen was utilized for the introduction of a cyano substituent on the porphyrin ring. This modification has a remarkable electronic effect on the ring. The resulting porphyrin cyanoaldehyde was further modified in Wittig condensations to give series of arylalkene- and arylalkyne-substituted derivatives. This substitution pattern caused significant redshifting and broadening of the B band, tuning from 433-446nm. Additionally the Q/B band intensity ratios show much higher values than observed for the parent porphyrin ZnTPP (0.20 vs. 0.03). Careful analysis of the electronic transitions using DFT and resonance Raman spectroscopy reveal that the substituent does not significantly perturb the electronic structure of the porphyrin core, which is still well described by Gouterman's four-orbital model. However, the substituents do play a role in elongating the conjugation length and this results in the observed spectral changes.

Publication Date


  • 2015

Citation


  • van der Salm, H., Wagner, P., Wagner, K., Officer, D. L., Wallace, G. G. & Gordon, K. C. (2015). Flexible tuning of unsaturated β-substituents on Zn porphyrins: A synthetic, spectroscopic and computational study. Chemistry: A European Journal, 21 (44), 15622-15632.

Scopus Eid


  • 2-s2.0-84945449686

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/1625

Has Global Citation Frequency


Number Of Pages


  • 10

Start Page


  • 15622

End Page


  • 15632

Volume


  • 21

Issue


  • 44

Place Of Publication


  • Germany