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Photocontrol over Molecular Shape: Synthesis and Photochemical Evaluation of Glycoazobenzene Macrocycles
Author(s) -
Despras Guillaume,
Hain Julia,
Jaeschke Sven Ole
Publication year - 2017
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.201701232
Subject(s) - photoisomerization , azobenzene , photochromism , molecular switch , chemistry , conformational isomerism , chirality (physics) , isomerization , circular dichroism , photochemistry , molecule , supramolecular chirality , crystallography , supramolecular chemistry , organic chemistry , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark , catalysis
Reversible shape switching due to external stimuli is an attractive property for the control of molecular features. Hence, we aimed at macrocycles to investigate photoswitching of molecular shape. We prepared the first carbohydrate‐based macrocycles comprising a photoresponsive azobenzene hinge. These macrocycles were readily obtained by cyclization of isothiocyanate‐armed bis‐azobenzene glycosides with piperazine. The unprotected macrocycles exhibit favorable photochromic properties in water and DMSO. Notably, the efficient trans → cis isomerization results in a remarkable shape transformation of the molecule. Additionally, the structure is characterized by restricted conformational freedom of the backbone, resulting in a single main conformer in each geometrical state ( trans or cis ). Measurement of optical rotation values and circular dichroism spectra revealed a tremendous change in chirality upon photoisomerization, with a strong helical induction in the cis state. These findings highlight the applicability of the new macrocycles as chiroptical molecular switches.