Cavity ring-down spectroscopy of the torsional motions of 1,4-bis(phenylethynyl)benzene

Stuart J Greaves; Emma L Flynn; Emma L Futcher; Eckart Wrede; Donocadh P Lydon; Paul J Low; Simon R Rutter; Andrew Beeby

doi:10.1021/jp054426h

Cavity ring-down spectroscopy of the torsional motions of 1,4-bis(phenylethynyl)benzene

J Phys Chem A. 2006 Feb 16;110(6):2114-21. doi: 10.1021/jp054426h.

Authors

Stuart J Greaves¹, Emma L Flynn, Emma L Futcher, Eckart Wrede, Donocadh P Lydon, Paul J Low, Simon R Rutter, Andrew Beeby

Affiliation

¹ University of Durham, Department of Chemistry, South Road, Durham DH1 3LE, UK.

PMID: 16466245
DOI: 10.1021/jp054426h

Abstract

The torsional motions of jet-cooled 1,4-bis(phenylethynyl)benzene (BPEB), a prototype molecular wire, were studied using cavity ring-down spectroscopy in the first UV absorption band (316-321 nm). The torsional spectrum of 1,4-bis(phenylethynyl)-2,3,5,6-tetradeuteriobenzene was also recorded in the gas phase. Both spectra were successfully simulated using simple cosine potentials to describe the torsional motions. The ground-state barrier to rotation was estimated to be 220-235 cm(-1), which is similar to that of diphenylacetylene (tolane). Complementary DFT calculations were found to overestimate the torsional barrier.