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Crystal Structure Analysis of Azo Pigments involving β‐Naphthol: A Review
Author(s) -
WHITAKER A.
Publication year - 1978
Publication title -
journal of the society of dyers and colourists
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 0037-9859
DOI - 10.1111/j.1478-4408.1978.tb03377.x
Subject(s) - tautomer , hydrogen bond , molecule , intramolecular force , chemistry , stacking , van der waals force , ring (chemistry) , crystallography , crystal (programming language) , crystal structure , hydrazone , group (periodic table) , stereochemistry , organic chemistry , computer science , programming language
The crystal structures of six azo pigments involving β‐naphthol have been determinea by single crystal X‐ray diffraction techniques. A review of these crystal structures indicates the existence of certain common features. It is found that the molecules exist as keto‐hydrazone tautomers with intramolecular hydrogen bonding which holds the molecule in the trans‐form. If the phenyl group is ortho substituted, this hydrogen bond is shared so as to hold the two ring systems, and hence the molecule, in the same plane. In the case of pigments where there is an anilide side group on the naphthol, the amido group is hydrogen bonded to the naphthol, but this bond may also be shared. The molecules are linked by van der Waals forces. A relationship between molecular stacking and the crystal morphology is pointed out.