155800-67-2Relevant academic research and scientific papers
Synthesis and photoswitching properties of liquid crystals derived from myo-inositol
Rahman, Md Lutfor,Yusoff, Mashitah Mohd,Kumar, Sandeep
, p. 35089 - 35098 (2014)
A new series of unconventional liquid crystal molecules derived from myo-inositol core were synthesized by linking six azobenzene units having terminal double bonds as polymerizable functional groups to myo-inositol. Differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction studies were carried out to determine mesomorphism in these materials. Thus, all compounds showed stable enantiotropic SmA phase which was independent of the chain length and chain parity. The photoswitching behaviour of these molecules in solutions showed E to Z isomerization in 8-10 s, whereas the reverse process took about 270-305 min. In solid film, the E-Z photoisomerization took 5 s, while the reverse transformation from Z to E state took 120 min. The photoswitching behaviour of these materials represents one of the fastest switching times so far observed in such materials and, therefore, they are good candidates for molecular switches.
Synthesis of new U-shaped azobenzene liquid crystals for photoswitching properties
Rahman, Md Lutfor,Sarkar, Shaheen M.,Yusoff, Mashitah M.,Kumar, Sandeep,Tschierske, Carsten
, p. 87019 - 87029 (2015/11/09)
A new series of liquid crystalline compounds comprising a U-shaped unit as central core incorporating azobenzene in the side arms and having terminal alkene functional groups, is synthesized and characterized by differential scanning calorimetry (DSC), polarized-light optical microscopy (POM), X-ray diffraction analysis and UV-vis spectroscopy. In the U-shaped series, all compounds showed stable enantiotropic monolayer SmA phases independent on the chain length and chain parity. These U-shaped molecules exhibit strong photoisomerisation behaviour in solutions and in solid state. The photoswitching properties of compounds showed trans to cis isomerization in about 15 seconds, whereas reverse process required much longer times ranging from 235-380 min in solutions. In case of solid film of 4a, E-Z photoisomerization takes around 4 s and the reverse transformation to original Z-E state takes about 74 min. The kinetic study using UV light irradiation shows that all compounds (4a-e) behave first order rate law throughout the relaxation time in solution. The effect of alkyl chain length for trans to cis is negligible whereas, cis to trans is substantial on the odd-even chain length. The photoisomerization study with variable light intensities shows that the photosaturation and thermal back relaxation times are decreased when intensity of the irradiated light is increased. Compounds did not degrade with light illumination at 10 mW cm-2. The reversible isomerization did not significantly decay after multiple cycles indicating that the photo-responsive properties are stable and repeatable. Thus, the photoswitching behaviour of these materials may be suitably exploited in the field of optical data storage device and in molecular switches for suitable switching times.
Synthesis and characterization of naphthalene-based banana-shaped liquid crystals for photoswitching properties
Rahman, Md Lutfor,Yusoff, Mashitah Mohd,Hegde, Gurumurthy,Malek, Muhammad Nor Fazli Abdul,Samah, Nurlin Abu,Srinivasa,Kumar, Sandeep
, p. 571 - 577 (2014/05/20)
A series of banana-shaped monomers containing naphthalene as central units, azobenzene in side arms with terminal alkenes were synthesized and characterized. Polarizing optical microscopy, DSC and X-ray diffraction measurements reveal that one compound processes a nematic phase while other four compounds exhibit B6 phase. The absorption spectrum of trans-azobenzene displays high-intensity π-π* transition at 365 and low-intensity n-π* transition at 450 nm. These molecules exhibit strong photoisomerisation behaviour in solutions in which trans to cis isomerisation takes 55 seconds whereas reverse process takes about 32 hours. Such a long thermal back relaxation is useful for creation of optical image storage devices. Banana-shaped monomers containing naphthalene as central units linked with azobenzene in side arms were processes mesophase properties. These molecules exhibit E/Z isomers and under UV irradiation trans (left) to cis (right) isomerisation takes 55 seconds whereas reverse process takes about 32 hours. Such a long thermal back relaxation is useful for creation of optical image storage at extremely right side.
