952052-75-4Relevant academic research and scientific papers
Exceptional dual fluorescent, excited-state intramolecular proton-transfer (ESIPT) columnar liquid crystals characterized by J-stacking and large Stokes shifts
Kanakala, Madhu Babu,Yelamaggad, Channabasaveshwar V.
, (2021/03/19)
Excited-State Intramolecular Proton-Transfer (ESIPT) fluorophores are emerging as promising future materials for electronic and biotechnological applications. ESIPT columnar (Col) liquid crystals (LCs) have been especially projected as the apt materials for advanced technological endeavors. But, there are hardly any explorations in this direction and thus, needing immediate attention. Herein we report on the synthesis, characterization, and ESIPT activity of a homologous series of novel phasmidic bis(N-salicylideneaniline) Col LCs. Optical microscopic, calorimetric and powder X-ray diffraction (XRD) studies evidence the occurrence of hexagonal columnar (Colh) phase having p6mm symmetry where the constituent slices result from the self-assembly of a pair of mesogens in a side-by-side manner facilitated by intense longitudinal π-π interactions. X-ray data confirm the absence of both directionally correlated tilting of the slices and transverse core-core interactions within the columns. Fluorescence probing clearly evidence the ESIPT occurring not only in DCM solution of the mesogens but also in their three-condensed states viz., solid, liquid crystal, and isotropic liquid phase; in general, two archetypal emission bands at ~430 nm (weak) and ~ 630 nm (strong) with large Stokes shifts (250–275 nm) of ESIPT phenomenon have been observed. The slow shift of emission maxima of the ESIPT fluorescence as a function of decreasing temperature without photoluminescence quenching coupled with the estimated tilt angle (?) of the slices normal to the columnar axis (37 to 42o), from the XRD data, confirm the formation of so-called Scheibe or J-aggregates. The redox activity, metal ion sensing ability, and solvatochromism of the mesogens have also been investigated. The study suggests that these ESIPT Col LCs with band-gap of about 3 eV can be regarded as wide-bandgap semiconducting materials having the electronic characteristics falling between those of conventional semiconductors and insulators.
Columnar liquid-crystalline phase from a series of symmetrical bent diphenylamine derivatives: Synthesis and characterization
Majumdar,Ansary, Inul,Roy
scheme or table, p. 160 - 167 (2011/05/03)
A series of symmetrical bent-shaped materials with six alkoxy chains at the terminal position has been designed and synthesized. All except one exhibit columnar mesophase behavior. The mesomorphic properties of the compounds have been studied with the help of polaralizing optical microscopy (POM) and differential scanning colorimetry (DSC) experiments.
A columnar mesophase from a disc-shaped molecule derived from triphenylamine: synthesis, mesomorphic behaviour and optical properties
Majumdar,Pal, Nilasish,Debnath, Pradip,Rao, Nandiraju V.S.
, p. 6330 - 6333 (2008/02/12)
The design and synthesis of a disc-like liquid crystalline compound using triphenylamine as a core has been achieved. The mesogenic properties were characterized by polarizing microscopy and differential scanning calorimetry and XRD studies. The compound
Rodlike metallomesogens containing nickel(II), palladium(II) and copper(II) based on novel enaminoketonato ligands
Roll, Carsten P.,Martin, Alexander G.,Goerls, Helmar,Leibeling, Guido,Guillon, Daniel,Donnio, Bertrand,Weigand, Wolfgang
, p. 1722 - 1730 (2007/10/03)
Several new enaminoketone mesogens were synthesized and coordinated to various metal salts to yield a variety of novel rodlike metal-containing liquid crystals. The mesophases were characterized by polarized optical microscopy (POM), differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS). Whereas the free ligands display SmA and nematic mesophases, the Ni II and PdII complexes give rise to SmC and nematic phases, and the paramagnetic CuII mesogens to a narrow temperature-range nematic mesophase only. The magnetic behaviour of the latter was studied by means of EPR and magnetic susceptibility (SQUID) measurements.
