Conformations and Structures of Two Novel Upper Rim Disubstituted Derivatives of Tetra-O-alkylcalix[4]arene: The Effect of Substituents

• DOI: 10.1007/s10847-004-6331-3
• Publication Date: 2005-06-14T09:47:28Z
• Authors: Gaosheng Yang; Chen Jin; Yizhi Li; Jing Hong; Ren Miao; Chuenmei Zhao; Zijian Guo; Longgen Zhu
• Keywords: 01 natural sciences; 0104 chemical sciences

Two new calix[4]arene derivatives, 5,17-dinitro-26,28-dimethyoxy-25,27-dipropoxycalix[4]arene (4) and 5,17-diamino-26,28-dimethyoxy-25,27-dipropoxycalix[4]arene (5), have been synthesized and fully characterized. The 1H NMR spectra measured in different solvents and temperatures indicated that the dominant conformer is partial cone for 4 and cone for 5, though there are some variations in relative ratio of partial cone to cone conformers. The structures of partial cone 4 and cone 5 are determined by X-ray crystallography. The different conformational behavior in compounds 4 and 5 is governed by the two substituents at the upper rim. The repulsion of the dipole due to the p-nitro substituents and weak interaction between methoxy group and the inverted anisole ring in the 4 may be responsible for stabilizing the partial cone conformation.