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From Low to Very High Birefringence in Bis(2‐pyridylimino)isoindolines: Synthesis and Structure–Property Analysis
Author(s) -
Wong Edwin W. Y.,
Ovens Jeffrey S.,
Leznoff Daniel B.
Publication year - 2012
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.201103421
Subject(s) - isoindoline , birefringence , polarizability , crystallography , molecule , chemistry , anisotropy , crystal structure , stereochemistry , medicinal chemistry , organic chemistry , optics , physics
A series of new substituted 1,3‐bis(2‐pyridylimino)isoindolines—1,3‐bis(2‐pyridylimino)‐5,6‐bis(2,6‐diisopropylphenoxy)isoindoline ( 2 b ), 1,3‐bis(2‐pyridylimino)‐5,6‐bis(4‐ tert ‐butylphenyl)isoindoline ( 2 c ), and 1,3‐bis(2‐pyridylimino)‐5‐ tert ‐butylisoindoline ( 2 d )—were synthesized and structurally characterized by single‐crystal X‐ray diffraction. The birefringence (Δ n ) of the crystals of unsubstituted 1,3‐bis(2‐pyridylimino)isoindoline ( 2 a ), 2 b , 2 c , and 2 d were measured and found to vary greatly, with Δ n values of 0.0654(3), 0.0629(17), 0.588(10), 0.701(12), respectively. A structure–property relationship for the birefringence values of 2 a – 2 d was outlined and indicated that the anisotropy of the polarizability of the molecules plays a crucial role in the birefringence of the crystals. The greatest birefringence values are achieved when the molecules are oriented in a face‐to‐face configuration intermolecularly, and along the crystallographic face being measured.