Liquid crystalline dihydroazulene photoswitches

TY - JOUR

T1 - Liquid crystalline dihydroazulene photoswitches

AU - Petersen, Anne Ugleholdt

AU - Jevric, Martyn

AU - Mandle, Richard J.

AU - Davis, Edward J.

AU - Cowling, Stephen J.

AU - Goodby, John W.

AU - Nielsen, Mogens Brøndsted

PY - 2015/10/13

Y1 - 2015/10/13

N2 - A large selection of photochromic dihydroazulene (DHA) molecules incorporating various substituents at position 2 of the DHA core was prepared and investigated for their ability to form liquid crystalline phases. Incorporation of an octyloxy-substituted biphenyl substituent resulted in nematic phase behavior and it was possible to convert one such compound partly into its vinylheptafulvene (VHF) isomer upon irradiation with light when in the liquid crystalline phase. This conversion resulted in an increase in the molecular alignment of the phase. In time, the meta-stable VHF returns to the DHA where the alignment is maintained. The systematic structural variation has revealed that a biaryl spacer between the DHA and the alkyl chain is needed for liquid crystallinity and that the one aromatic ring in the spacer cannot be substituted by a triazole. This work presents an important step towards employing the dihydroazulene-vinylheptafulvene photo/thermoswitch in photoactive liquid crystalline materials.

AB - A large selection of photochromic dihydroazulene (DHA) molecules incorporating various substituents at position 2 of the DHA core was prepared and investigated for their ability to form liquid crystalline phases. Incorporation of an octyloxy-substituted biphenyl substituent resulted in nematic phase behavior and it was possible to convert one such compound partly into its vinylheptafulvene (VHF) isomer upon irradiation with light when in the liquid crystalline phase. This conversion resulted in an increase in the molecular alignment of the phase. In time, the meta-stable VHF returns to the DHA where the alignment is maintained. The systematic structural variation has revealed that a biaryl spacer between the DHA and the alkyl chain is needed for liquid crystallinity and that the one aromatic ring in the spacer cannot be substituted by a triazole. This work presents an important step towards employing the dihydroazulene-vinylheptafulvene photo/thermoswitch in photoactive liquid crystalline materials.

U2 - 10.1039/c5ra18649h

DO - 10.1039/c5ra18649h

M3 - Journal article

SN - 2046-2069

VL - 5

SP - 89731

EP - 89744

JO - RSC Advances

JF - RSC Advances

IS - 109

ER -