半菁化合物热行为和晶体结构的研究

Thermal Behaviors and Crystal Structure of Hemicyanines

合成了5个不同烷基链长的半菁化合物:Me_2NC_6H_4CH=CHC_5H_4NC_nH_2n+1Br(n=16,12,4,2和1)。由可见光谱、红外光谱、差热(DTA)、热重(TG)谱、微分扫描量热分析和偏光显微镜研究结果,讨论了烷基链长的变化对半菁化合物有关性质的影响。首次发现n=16时半菁化合物为近晶型双变性液晶,90°偏光显微镜下,呈典型的焦锥织态结构。测定了化合物Me_2NC_6H_4CH=CHC_5H_4NC_2H_5Br·nH_2的晶体结构。晶体属单斜晶系,空间群P2_1/C,晶胞参数:a=1.6125(9),b=1.7391(12),c=1.8784(8)nm,β=99.794(8)°V=5.220(5)nm^3,Z=12。

5 hemicyanines with the compositions of Me_2NC_6H_4CH—CH—C_5H_4NC_nH_(2n+1)Br(n=16,12,4,2 and 1)have been synthesized and char-acterized by elemental analysis,thermalgravimetric,differential thermal analysis(TG-DTA),differential scan calorimetry(DSC),ultraviolet and infrared spec-troscopy.For the first time,a hemicyanine Me_2NC_6H_4CH=CHC_5H_4NC_(16)H_(33)Brhas been characterized to be of a mesogenic behavior with typical focal conical tex-ture.The structure of Me_2NC_6H_4CH=CHC_5H_4NC_2H_5Br.nH_2O has been deter-mined by singal crystal X-ray diffraction.The crystal belong to monoclinic,P2_1/Cspace group.The crystal parameters are as follows:a=1.612 5(8),b=1.739 1(12),c=1.878 4(8)nm,β=99.794(8)°,V=5.220(5)nm^3,Z=12.