1C06 液晶性ビフェニルエステル類の結晶構造 : エステル結合の配列に及ぼす末端鎖の影響

抄録

Biphenyl esters are typical mesogens with various mesophases according to substiments. Relationships between molecular structures and molecular packings are essential to understand the mesophase behavior. We have determined crystal structures for biphenyl esters, X-C_6H_4-C_6H_4-COO-C_6H_4-Y, where X, Y = C_8H_<17>O and/or C_8H_<17> (series 8-8) and X, Y = C_8H_<17>O, C_8H_<17>and/or CH_3O, CH_3 (series 8-1). Almost all compounds have one-dimensional chains of close arrangements of ester linkages. The arrangements are classified as follows. Pattern I is close arrangements of ester C=O・・・C=O. Pattern II is C=O・・・O-C=O, which is divided into two subgroups according to the O・・・O distances, shorter (3.28Å〜3.37Å ) (II-(1)) and longer (3.83Å 4.17Å) (I-(2)). The exception is the biphenyl ester with X = methyl and Y = octyl, which shows no special interaction between ester linkages. The packing modes of ester linkages are closely related to the melting points.