Synthesis and mesomorphic characterization of azoesters with a coumarin ring

Dave, Jayrang S.; Menon, Meera; Patel, Pratik

doi:10.1080/02678290110114341

Cited by 16 publications

(3 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The data in Table 1 and Figure 3 reveal that all coumarinesters, I n , series are non-mesomorphic. Conversely, all compounds in Coumarin azoesters group II n are enantiotrpically mesomorphic, these results are consistent with previous finding [30]. All members of group II n are dimorphic exhibit smectic C (SmC) and nematic phases (N) except II 16 is monomorphic showing only SmC phase.…”

Section: Mesophase Behavior Of the Investigated Coumarin Derivativessupporting

confidence: 92%

DFT Calculations and Mesophase Study of Coumarin Esters and Its Azoesters

2018

View full text Add to dashboard Cite

Two groups of coumarin derivatives, 4-methyl-2-oxo-2H-chromen-7-yl 4-alkoxybenzoates (coumarin esters), In, and 4-methyl-2-oxo-2H-chromen-7-yl 4-(2-(4-alkoxyphenyl)diazenyl) benzoates (coumarin azoesters), IIn, were synthesized and investigated for their mesophase behavior and stability. Each group constitutes five series that differ from each other by length of the mesogenic part. Within each homologous series, the length of the terminal alkoxy group varies between 6, 8, 10, 12 and 16 carbons. Mesophase behavior was investigated by differential scanning calorimetry (DSC) and identified by polarized light microscopy (PLM). Density functional theory (DFT) calculations for coumarin derivatives were discussed. The results revealed that the incorporation of azo group incorporated in the mesogenic core decreases the energy differences, increases the dipole moments and stabilities of coumarin azoesters series more than coumarin esters.

show abstract

Section: Mesophase Behavior Of the Investigated Coumarin Derivativessupporting

confidence: 92%

DFT Calculations and Mesophase Study of Coumarin Esters and Its Azoesters

2018

View full text Add to dashboard Cite

show abstract

“…For low molecular mass systems, it was realised that thermomesomorphism arises if aryl substituents are attached to the 6-or 7-position of the benzopyran-2H-one core via an ester linkage. [39][40][41][42][43][44] Alternatively, modification of the coumarin heterocycle with a carbonyl hydrazide function [45] or fusing with an additional pyrazolone ring [46] enforces mesophase formation by hydrogen bonding between the molecules. Emission behaviour from those low molecular mass coumarin mesogens was not documented.…”

Section: Introductionmentioning

confidence: 99%

Coumarin-based emissive liquid crystals

Buchs

Gäbler²,

Janietz

et al. 2014

Liquid Crystals

View full text Add to dashboard Cite

Calamitic luminophores are presented based on an elongated aryl-substituted coumarin core. The substitution pattern at terminal and lateral positions were systematically modified. The new compounds exhibit smectic C and/or nematic liquid crystalline phases. The chromophores show fluorescence in the blue spectral region. The benzopyranones are miscible with acrylate-substituted reactive nematic mesogens. Uniaxial orientation of the mixed systems was achieved by surface-assisted alignment on polyimide orientation layers. The film anisotropy was stabilised by subsequent photocrosslinking. The crosslinked oriented films display linear polarised photoluminescence upon isotropic excitation

show abstract

“…[7][8][9] Recently, it has been also found that coumarin containing polymers can be used as a new kind of photo-alignment layer for liquid crystals, where the photodimerization of the coumarin unit occurs by exposure to UV light and the direction of orientation of the liquid crystals can be adjusted by the polarization direction of the irradiation light. [10][11][12][13][14] Furthermore, a kind of liquid crystal display model has been realized by dispersion of coumarin dyes into nematic liquid crystals. [15][16][17] Recently, the preparation of liquid crystalline cyclic tetramethyltetrasiloxanes, cyclic pentamethylpentasiloxanes and other cyclic siloxanes has caused scientific interest, because these materials exhibit properties intermediate between low molecular weight and polymeric liquid crystals.…”

Section: Introductionmentioning

confidence: 99%