Premium
Towards Photocontrol over the Helix–Coil Transition in Foldamers: Synthesis and Photoresponsive Behavior of Azobenzene‐Core Amphiphilic Oligo( meta ‐phenylene ethynylene)s
Author(s) -
Khan Anzar,
Hecht Stefan
Publication year - 2006
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.200501564
Subject(s) - azobenzene , chromophore , photochromism , amphiphile , folding (dsp implementation) , helix (gastropod) , chemistry , oligomer , photochemistry , phenylene , polymer chemistry , materials science , molecule , polymer , organic chemistry , copolymer , ecology , snail , electrical engineering , biology , engineering
of photochromic azobenzene units into amphiphilic oligo( meta ‐phenylene ethynylene)s allowed photocontrol over the helix–coil transition in this important class of foldamers. Two design principles were followed in efforts to accommodate cis ‐ and trans ‐azobenzene moieties within the helical structure to selectively turn the helical state on and off, respectively. Several oligomer series with varying connectivities to the central azobenzene chromophore were synthesized and these photochromic oligomers were investigated with regard to their folding behavior in both dark and irradiated states. Both the foldamers’ chain lengths and the electronic structures of the azobenzene moieties had to be optimized to ensure folding differences and selective excitation of the photochrome. The design of such stimuli‐responsive macromolecules, displaying large structural changes upon irradiation, should guide the design of future materials in, for example, “smart” delivery applications.