Computational studies of [1]benzothieno[2,3-c]naphtho[1,2-f]quinoline

Valentin A Semenov; Gary E Martin; Leonid B Krivdin

doi:10.1002/mrc.5334

Computational studies of [1]benzothieno[2,3-c]naphtho[1,2-f]quinoline

Magn Reson Chem. 2023 May;61(5):301-305. doi: 10.1002/mrc.5334. Epub 2023 Feb 13.

Authors

Valentin A Semenov¹, Gary E Martin², Leonid B Krivdin¹

Affiliations

¹ A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia.
² Department of Chemistry and Biochemistry, Seton Hall University, South Orange, New Jersey, USA.

PMID: 36733267
DOI: 10.1002/mrc.5334

Abstract

Early NMR studies of several heterohelicenes containing an annular nitrogen atom and a thiophene ring in their structure suggested the possibility of the lengthening of the carbon-carbon bonds in the interior of the helical turn of the molecule based on the progressive more shielded nature of ¹³ C resonances toward the center of the helical turn. Computational chemistry capabilities when those NMR studies were performed were primitive in comparison to what is now possible. We now report the optimized geometry and a comparison of the calculated versus observed ¹ H and ¹³ C NMR chemical shift assignments for [1]benzothieno[2,3-c]naphtho[1,2-f]quinoline that confirms these suspicions.

Keywords: 13C NMR; 1H NMR; DFT; heterohelicene; molecular geometry.