Assignment of the Deuterium Quadrupolar Splittings for the End-chain of 4-cyano-4'-octylbiphenyl in the Nematic Phase: A Test Between Theoretical Models for End-chain Conformational Motion and Orientational Ordering

Abstract 4-Cyano-4'-(1,1,5,5-d 4-octyl)-biphenyl and 4-cyano-4'-(1,1,6,6-d4 ,-octyl)-biphenyl have been synthesized and the deuterium quadrupole splittings measured for their nematic phases. The results, when combined with previous measurements on other specifically deuteriated derivatives [Mol. Phys., 42, 565 (1981)], enable a virtually complete assignment to be made of the quadrupolar splittings in the deuterium nmr spectrum of the perdeuteriated end-chain of this mesogen. The assignment is shown to be consistent with that proposed by Emsley, Luckhurst and Stockley [Proc. Roy. Soc., A381, 117 (1982)] and with the single frame model proposed by Samulski and Dong [J. Chem. Phys., 77, 5090 (1982)], but inconsistent with Samulski and Dong's inertial frame model.