An Infrared Spectroscopic Study ofp-n-Alkoxybenzoic Acids
作者:
Paul Painter,
Chris Cleveland,
Mike Coleman,
期刊:
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
(Taylor Available online 2000)
卷期:
Volume 348,
issue 1
页码: 269-293
ISSN:1058-725X
年代: 2000
DOI:10.1080/10587250008024811
出版商: Taylor & Francis Group
关键词: Order/Disorder;Carbonyl Splitting Stretching Vibrations;Crystallin/LC Forms
数据来源: Taylor
摘要:
The infrared spectra of variousp-n-alkoxybenzoic acids are reported. The carbonyl stretching region of these materials is surprisingly sensitive to packing within the various crystal forms, a consequence of the sensitivity of these modes to hydrogen bonding and transition dipole coupling. The isotypic crystal form found in those acids with n>6 are characterized by a splitting in the carboxyl C=O stretching region, a consequence of interactions between the disordered arrangement of carboxyl groups from layer to layer. This splitting is not observed in those alkoxybenzoic acids where n<7. The infrared spectra also show that there is a solid state transformation from the crystalline state to conformationally disordered or ``condis” crystals as intermediates between the crystalline and liquid crystalline forms.
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