124774-91-0Relevant academic research and scientific papers
Synthesis and characterization of photoactive azobenzene-based chromophores containing a bulky cholesteryl moiety
Yang, Po-Chih,Lu, Ya-Ling,Li, Chung-Yuan
, p. 129 - 137 (2012/06/04)
This study describes the synthesis of a series of azobenzene-based chromophores bearing pendent bulky cholesteryl groups, using esterification reactions. The chromophores were composed of liquid crystalline mesophases with six or eleven methylene segments as spacers, and with electron-donating (OCH3) and electron-withdrawing (NO2) terminal groups. The target compounds were characterized by nuclear magnetic resonance spectroscopy, differential scanning calorimetry, polarizing optical microscopy, absorption, and photoluminescence spectroscopies. All the azobenzene derivatives with six or eleven methylene segments revealed chiral nematic phases. We investigated the effects of these photochromic compounds' structures on E/Z photoisomerization under UV irradiation. Chromophores containing the electron-withdrawing nitro-group (NO2) underwent a faster rate of Z to E isomerization in darkness than the electron-donating (OCH3) groups did; the isomerization process proceeded via a rotation mechanism. Self-assembled aggregates of C6 solution exhibited enhanced fluorescence in THF/water mixtures at 10% water fraction.
Synthesis of azobenzene-functionalized star polymers via RAFT and their photoresponsive properties
Alam, Md. Zahangir,Shibahara, Akihisa,Ogata, Tomonari,Kurihara, Seiji
, p. 3696 - 3703 (2012/02/05)
Azobenzene-functionalized star polymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. First, azobenzene-functionalized linear macro chain transfer agents (Macro-CTA) were synthesized by RAFT polymerization of 6-[4-(4′-Methoxyphenylazo)phenoxy] hexylmethacrylate (MAz6Mc) using 2-(2′-cyanopropyl)dithiobenzoate (CPDB) as RAFT agent in presence of AIBN as initiator in anisole. Subsequently, star azopolymers were synthesized by polymerization of a difunctional azomonomer, BMA2Az, with resultant Macro-CTA in presence of AIBN as initiator in anisole. Star azopolymers were characterized by GPC and spectroscopic methods. Thermal properties of star azopolymers were determined by DSC and TMA. Molecular weight versus conversion and molecular weight versus polymerization time attest to living polymerization characteristics. Photoisomerization behaviors of star azopolymers were studied by irradiation of both UV and visible light. Surface relief gratings were inscribed on star azopolymer films upon exposure to an interference pattern of (RCP + RCP) Ar+ laser. A diffraction efficiency of 20% was obtained by exposure of Star-8 K(2.6 K) polymer film to an (RCP + RCP) Ar+ laser for about 30 min. Surface relief grating structures were investigated by AFM and polarized optical microscopy.
