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The Effect of Fluorination: A Crystallographic and Computational Study of Mesogenic Alkyl 4‐[2‐(Perfluorooctyl)ethoxy]benzoates
Author(s) -
Yano Megumi,
Taketsugu Tetsuya,
Hori Kayako,
Okamoto Hiroaki,
Takenaka Shunsuke
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400123
Subject(s) - benzoates , alkyl , alkoxy group , mesogen , intermolecular force , chemistry , crystallography , liquid crystal , side chain , crystal (programming language) , crystal structure , stereochemistry , materials science , molecule , organic chemistry , polymer , liquid crystalline , computer science , programming language , optoelectronics
The series of alkyl 4‐[2‐(perfluorooctyl)ethoxy]benzoates ( F8‐ n ) shows a systematic change of crystal structures depending on the length of the alkyl chain: separate packing of perfluorooctyl (R f ) and alkyl (R h ) chains from each other for shorter ( n =2) and longer ( n =11) members, alternate packing of R f and R h chains for middle ( n =6,7) members, and an intermediate type of packing for n =4. Semiempirical MO calculations show slightly repulsive interactions between the R f chains, and attractive ones between R f and R h chains and between R h and the core of a molecular pair. It is concluded that fluorination determines the molecular shape of the crystal structures by making the chain rigid. It is confirmed that the interactions between R f chains are small compared with those between other moieties and that they are forced to aggregate owing to the exclusion from other moieties. Thus, the effect is dependent on the geometries and intermolecular interactions of the other moieties.