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Preparation of Cocrystals of 1,4‐Diimidazolylbutadiene with a Template Molecule and Dependence of the Cocrystal Photochemical Products on Wavelength
Author(s) -
Meng Fanxing,
Min Jing,
Wang Chunyu,
Wang Liyan
Publication year - 2016
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201600079
Subject(s) - cocrystal , dimer , chemistry , photochemistry , derivative (finance) , molecule , yield (engineering) , crystal (programming language) , cycloaddition , crystallography , crystal engineering , crystal structure , organic chemistry , materials science , hydrogen bond , supramolecular chemistry , catalysis , computer science , financial economics , economics , metallurgy , programming language
A cocrystal of (1 E ,3 E )‐1,4‐di(1 H ‐imidazol‐1‐yl)buta‐1,3‐diene (DIBD) with 5‐methoxyresorcinol, a DIBD crystal and a DIBD monohydrate crystal were prepared and characterized by single‐crystal X‐ray analysis. The cocrystal satisfies Schmidt's topochemical postulate for photodimerization, whereas the other two crystals do not. The DIBD in the cocrystal was irradiated with 313.5 nm light to produce a dimer (a divinylcyclobutane derivative) in high yield through a [2+2] cycloaddition reaction. This dimer then underwent a Cope rearrangement by heating to produce a second dimer, a cyclooctadiene derivative. This second dimer can also be obtained by irradiating the cocrystal with a broadband Hg lamp without an optical filter. It was found that 257 nm light is critical for formation of the second dimer. The dependence of the photochemical products on wavelength may originate from the characteristic UV absorption.