TY - JOUR
T1 - Towards photocontrol over the helix-coil transition in foldamers
T2 - Synthesis and photoresponsive behavior of azobenzene-core amphiphilic oligo(meta-phenylene ethynylene)s
AU - Khan, Anzar
AU - Hecht, Stefan
PY - 2006/6/14
Y1 - 2006/6/14
N2 - Introduction 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.
AB - Introduction 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.
KW - Azo compounds
KW - Chirality
KW - Foldamers
KW - Helical structures
KW - Photochromism
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U2 - 10.1002/chem.200501564
DO - 10.1002/chem.200501564
M3 - Article
C2 - 16528779
AN - SCOPUS:33745453830
SN - 0947-6539
VL - 12
SP - 4764
EP - 4774
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 18
ER -