Journal of the American Chemical Society p. 7797 - 7803 (1987)
Update date:2022-08-29
Topics:
Drotloff, H.
Rotter, H.
Emeis, D.
Moeller, M.
Cyclotetradecane shows a thermal transition 7 K below the melting point.The high-temperature crystal phase is characterized by high molecular mobility and easy deformation.Thermal analysis, MAS 13C NMR with high-power proton decoupling, X-ray diffraction, and birefringence experiments have been performed and are discussed with respect to the onset of molecular motion and molecular disorder.The NMR experiments clearly show the onset of a conformational interconversion process well below the transition, while the positional, orientational, and conformational order are largly preserved.The same applies to some extent even within the high-temperature crystal phase.It is thus shown that molecular dynamics must be strictly differentiated from molecular and crystal disorder.Disordering of molecules with low symmetry such as cyclotetradecane is shown to result in rather large transition entropies, even when the molecular motins are jumplike and involve only minor disorder in the crystal.The concepts of liquid crystal, plastic crystal, and condis-crystal are discussed with regard to the classification of the mesomorphic character of the high-temperature crystal phase of cyclotetradecane.It is classified as a molecule that shows a mesophase with partial orientational disorder and high conformational mobility.
View MoreContact:17316303296
Address:240 Amboy Ave
MS( MAOSHENG )Chemical CO.,LTD
Contact:+86-519-82726678.82726378
Address:TAOXI INDUSTRY ZONE JINTAN
Nanjing Yuance Industry&Trade Co., Ltd.
website:http://www.njyuance.cn/
Contact:+86-25-85439097
Address:B1702, Aoti Bldg, No. 130, Aoti Avenue, Nanjing, China
Changzhou Anyi Biochem Co., Ltd.
Contact:+86-519-88836158
Address:no,51 caoda
Contact:+86-515-88356562
Address:No.2, West Daqing Road, Yancheng, Jiangsu, China
Doi:10.1016/S0022-328X(00)90359-0
(1974)Doi:10.1246/bcsj.45.2096
(1972)Doi:10.1021/jo01332a012
(1979)Doi:10.1021/jo01073a005
(1960)Doi:10.1021/ja01072a028
(1964)Doi:10.1021/jo00018a002
(1991)