Excited-state electronic asymmetry prevents photoswitching in terthiophene compounds

Strudwick, B. H., Zhang, J., Hilbers, M. F., Buma, W. J., Woutersen, S., Liu, S. H. and Hartl, F. ORCID: https://orcid.org/0000-0002-7013-5360 (2018) Excited-state electronic asymmetry prevents photoswitching in terthiophene compounds. Inorganic Chemistry, 57 (15). pp. 9039-9047. ISSN 0020-1669 doi: 10.1021/acs.inorgchem.8b01005

Abstract/Summary

The diarylethene moiety is one of the most extensively used switches in the field of molecular electronics. Here we report on spectroscopic and quantum chemical studies of two diarylethene-based compounds with a non-C3-symmetric triethynyl terthiophene core symmetrically substituted with RuCp*(dppe) or trimethylsilyl termini. The ethynyl linkers are strong IR markers that we use in time-resolved vibrational spectroscopic studies to get insight into the character and dynamics of the electronically excited states of these compounds on the picosecond to nanosecond time scale. In combination with electronic transient absorption studies and DFT calculations, our studies show that the conjugation of the non-C3-symmetric triethynyl terthiophene system in the excited state strongly affects one of the thiophene rings involved in the ring closure. As a result, cyclization of the otherwise photochromic 3,3″-dimethyl-2,2′:3′,2″-terthiophene core is inhibited. Instead, the photoexcited compounds undergo intersystem crossing to a long-lived triplet excited state from which they convert back to the ground state.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/78401
Identification Number/DOI	10.1021/acs.inorgchem.8b01005
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Publisher	ACS Publications
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