Picosecond time-resolved infra-red spectroscopic study of a water-soluble cationic copper-porphyrin with nucleic acids

Keane, P. M. ORCID: https://orcid.org/0000-0003-2828-8512, Graczyk, D., Sazanovich, I. V. ORCID: https://orcid.org/0000-0002-8000-7645, Towrie, M., Quinn, S. J. ORCID: https://orcid.org/0000-0002-7773-8842 and Kelly, J. M. ORCID: https://orcid.org/0000-0002-3706-1777 (2026) Picosecond time-resolved infra-red spectroscopic study of a water-soluble cationic copper-porphyrin with nucleic acids. Physical Chemistry Chemical Physics. ISSN 1463-9084 doi: 10.1039/d5cp04939c

Abstract/Summary

The greater abundance and lower cost of copper make its porphyrin derivatives an attractive alternative to precious-metal based photosensitisers. The Cu(II) complex of 5,10,15,20-meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (CuTMPyP4) is a useful photophysical probe for biomolecules. It is non-luminescent in aqueous solution, as it forms a metastable five-coordinate water complex after photo-excitation. CuTMPyP4 is known to bind to DNA both through the grooves and by intercalation. In this paper picosecond transient absorption (TA) and time-resolved infra-red (TRIR) spectra of CuTMPyP4 in D2O and in the presence of polydeoxythymidylic acid (poly(dT) and the double-stranded oligonucleotides {d(GC)5}2 and {d(CGCAAATTTGCG)}2 are reported. These spectra show characteristic features depending on whether a five-coordinate transient species or the four-coordinate triplet excited state is formed. Notably, in the case of thymine-containing nucleic acids the TRIR method unambiguously demonstrates the binding of the porphyrin to the C2=O carbonyl group of that nucleobase.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/129039
Identification Number/DOI	10.1039/d5cp04939c
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Publisher	Royal Society of Chemistry
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