Syntheses, Electronic Structures, and Dichroic Behavior of Dinuclear Cyclopalladated Complexes of Push−Pull Azobenzenes
摘要:
Eight new chloride-/acetate-bridged dimeric Pd-II complexes have been synthesized by using 4-heptoxyazobenzenes 4'-substituted with groups of varying electron-withdrawing strength (NO2, CN, F, or CO2Et). The effects of charge density distribution and the bridging ligand on the relative proportions of structural and geometrical isomers produced is explored by using NMR spectroscopy. UV-vis spectroscopy reveals a single low-energy absorption for each proligand but three distinct bands for each of the complexes. The origins of the observed absorptions are inferred from the effects of changing the bridging ligands and corroborated by time-dependent density functional theory (TD-DFT) calculations. Dichroic ratio (DR) measurements in two different liquid-crystal (LC.) hosts show decreased performance upon complexation, although the results are notably wavelength dependent. The lowest energy absorption band, associated with intraligand charge-transfer transitions, displays superior dichroism with respect to the adjacent band at higher energy. The transition dipole moment directions calculated via TD-DFT correlate with the observed DR results, implying a decrease in alignment within the LC hosts for the complexes with respect to their proligands.
Wide Temperature Range Azobenzene Nematic and Smectic LC Materials
摘要:
We have developed a series of azobenzene liquid crystals (azo LC) compounds, both multicomponent as well as single component, that possess room temperature nematic and smectic phases. Some of these materials have a wide mesophase temperature range which makes them useful for a variety of practical applications. Two main strategies were used for controlling the temperature range of these mesogenic azo LC materials: 1) chemical modification of azobenzene molecules with different terminal pendants; and 2) development of multicomponent compositions. These materials were highly photosensitive exhibiting nonlinear refraction and transmission at nanowatt/microwatt power levels. Physical, electro- and nonlinear-optical parameters of many of these materials have been characterized in detail.
The present disclosure provides an intralocular-lens (IOL) or ophthalmic device including an optic and at least one haptic, at least a portion of which is formed from a photoresponsive shape memory polymer network, such as a polydomain azo liquid crystalline polymer network (PD-LCN). The present disclosure further provides systems and methods for adjusting the position of such an IOL or other ophthalmic device using polarized laser radiation.
Syntheses, Electronic Structures, and Dichroic Behavior of Dinuclear Cyclopalladated Complexes of Push−Pull Azobenzenes
作者:Octavia A. Blackburn、Benjamin J. Coe
DOI:10.1021/om101189f
日期:2011.4.25
Eight new chloride-/acetate-bridged dimeric Pd-II complexes have been synthesized by using 4-heptoxyazobenzenes 4'-substituted with groups of varying electron-withdrawing strength (NO2, CN, F, or CO2Et). The effects of charge density distribution and the bridging ligand on the relative proportions of structural and geometrical isomers produced is explored by using NMR spectroscopy. UV-vis spectroscopy reveals a single low-energy absorption for each proligand but three distinct bands for each of the complexes. The origins of the observed absorptions are inferred from the effects of changing the bridging ligands and corroborated by time-dependent density functional theory (TD-DFT) calculations. Dichroic ratio (DR) measurements in two different liquid-crystal (LC.) hosts show decreased performance upon complexation, although the results are notably wavelength dependent. The lowest energy absorption band, associated with intraligand charge-transfer transitions, displays superior dichroism with respect to the adjacent band at higher energy. The transition dipole moment directions calculated via TD-DFT correlate with the observed DR results, implying a decrease in alignment within the LC hosts for the complexes with respect to their proligands.
Wide Temperature Range Azobenzene Nematic and Smectic LC Materials
作者:U. Hrozhyk、S. Serak、N. Tabiryan、T. J. Bunning
DOI:10.1080/15421400600655733
日期:2006.9
We have developed a series of azobenzene liquid crystals (azo LC) compounds, both multicomponent as well as single component, that possess room temperature nematic and smectic phases. Some of these materials have a wide mesophase temperature range which makes them useful for a variety of practical applications. Two main strategies were used for controlling the temperature range of these mesogenic azo LC materials: 1) chemical modification of azobenzene molecules with different terminal pendants; and 2) development of multicomponent compositions. These materials were highly photosensitive exhibiting nonlinear refraction and transmission at nanowatt/microwatt power levels. Physical, electro- and nonlinear-optical parameters of many of these materials have been characterized in detail.