- Flavylium Salts: A Blooming Core for Bioinspired Ionic Liquid Crystals
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Thermotropic ionic liquid crystals based on the flavylium scaffold have been synthesized and studied for their structure-properties relationship for the first time. The mesogens were probed by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD). Low numbers of alkoxy side chains resulted in smectic (SmA) and lamello-columnar (LamCol) phases, whereas higher substituted flavylium salts showed Colro as well as ordered and disordered columnar (Colho, Colhd) mesophases. Mesophase width ranged from 13 K to 220 K, giving access to room temperature liquid crystals. The optical properties of the synthesized compounds were probed towards absorption and emission properties. Strong absorption with maxima between 444 and 507 nm was observed, and some chromophores were highly emissive with quantum yields up to 99 %. Ultimately, mesogenic and dye properties were examined by temperature-dependent emissive experiments in the solid state.
- Forschner, Robert,Knelles, Jakob,Bader, Korinna,Müller, Carsten,Frey, Wolfgang,K?hn, Andreas,Molard, Yann,Giesselmann, Frank,Laschat, Sabine
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supporting information
p. 12966 - 12980
(2019/11/05)
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- Columnar self-assembly of novel benzylidenehydrazones and their difluoroboron complexes: Structure-property correlations
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Organoboron complexes are considered to be an important class of optically dynamic materials and because of their imperative properties, they have been unceasingly studied in a wide range of scientific areas. In this context, a new family of D-A-D′ archit
- Vinayakumara,Swamynathan,Kumar, Sandeep,Adhikari, Airody Vasudeva
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supporting information
p. 7099 - 7108
(2019/05/16)
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- Light-Emitting Chiral Nematic Dimers with Anomalous Odd-Even Effect
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In this report, based on the results derived from the extensive study into the thermal and photophysical properties, an anomalous mesomorphic behavior of photoluminescent, chiral nematic (N*) liquid crystalline dimers, belonging to two different series ha
- Veerabhadraswamy,Bhat, Sachin A.,Hiremath, Uma S.,Yelamaggad, Channabasaveshwar V.
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p. 2836 - 2851
(2019/11/11)
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- Supramolecular columnar self-assembly of wedge-shaped rhodanine based dyes: Synthesis and optoelectronic properties
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The development of small π-conjugated functional organic molecules capable of forming supramolecular columnar self-assembly, is a rapidly growing area of material research. In this context, the present work describes the design and synthesis of a new seri
- Vinayakumara,Kumar, Sandeep,Adhikari, Airody Vasudeva
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p. 215 - 222
(2018/11/20)
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- Room temperature helical fluids in single-component systems
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Technologically significant chiral nematic (N*) phase is a helicoidal superstructure, that is generally formed by the spontaneous self-assembly of entire chiral mesogens (mostly calamitics) or by the LC mixtures where a chiral dopant is being added to the
- Shanker,Bindushree,Chaithra,Pratap,Gupta, Ravindra Kumar,Achalkumar,Yelamaggad
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p. 849 - 858
(2018/12/10)
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- Effect of regioisomerism on the self-assembly, photophysical and gelation behavior of aroylhydrazone based polycatenars: Synthesis and characterization
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In this paper we report five series of aroylhydrazone based polycatenars differing from each other in number and position of alkoxy chains on one end of the core; keeping other end the same. A systematic variation in the structures was carried out to understand the effect of position and chain length on the mesophase behavior. In the case of single alkoxy chain at 4-position, there is a transition from Smectic C to Smectic A mesophase during cooling and Smectic A to Smectic C transition in heating cycle in all the homologues except n = 6 & n = 8. In the case of two alkoxy chains at 3-, 5-positions, the compounds are non-mesogenic in nature. On changing the position of alkoxy chains from 3-, 5-positions to 3-, 4-positions, intermolecular forces weaken and these compounds become liquid crystalline and show columnar rectangular mesophase resulting from the effect of regioisomerism. Moving on to the series with three alkoxy chains, it was observed that 2-, 3-, 4-trialkoxy substituted compounds exhibit columnar rectangular mesophase except lower chain length (n = 6 & 8) while 3-, 4-, 5-trialkoxy substituted aroylhydrazones show columnar rectangular mesophase; except n = 10 which shows columnar oblique mesophase. Thus it was established that on increasing density of alkoxy chains around one terminal, mesophase changes from smectic to columnar mesophase. Temperature dependent Raman studies confirm the presence of intermolecular hydrogen bonding. Further, effect of substitution pattern did not show much influence on the photophysical properties of the mesogenic series in solid and solution state. However, the non-mesogenic series showed a different absorption and emission transition from the mesogenic series in solid and solution state. Solid state fluorescence studies show almost similar emission maxima in all the series. However, it was also noticed that non-mesogenic series show maximum red shifted emission maxima in solid state as compared to that of solution. All the series showed good gelation properties with less than 1% CGC (wt%) suggesting the strong ability of molecules to form gel. These H-bonded liquid-crystalline gels have immense potential for applications in emissive displays.
- Kanth, Priyanka,Singh, Hemant Kumar,Kumar, Vijay,Singh, Sachin Kumar,Rao, D.S. Shankar,Prasad, S. Krishna,Singh, Bachcha
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- Water-soluble BODIPY (boron-dipyrromethene) derivatives with different hydrophobic chains and preparation method of water-soluble BODIPY derivatives
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The invention relates to a synthetic method of amphiphilic BODIPY (boron-dipyrromethene) fluorescent dye derivatives. Through molecular design, a series of BODIPY derivatives with different hydrophobic chains are prepared with a Grignard reaction and a qu
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Paragraph 0083; 0084; 0085
(2016/10/10)
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- Photoluminescent discotic liquid crystals derived from tris(N-salicylideneaniline) and stilbene conjugates: Structure-property correlations
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Luminescent discotic liquid crystals based on tris(N-salicylideneaniline)s [TSANs] bearing trans-stilbene fluorophores have been synthesized. Their mesomorphic and photophysical properties were studied. These TSANs existing in the form of C3h and Cs geometrical isomers of the keto-enamine tautomer self-assemble to form the columnar phase and exhibit fluorescence both in solution and mesophase states. These columnar mesophases also exhibit frozen (glassy) columnar phase, which ensures preserved fluorescence intensity, defect free alignment and simultaneous restriction on the motion of ionic impurities. These features make them promising candidates for the use in organic light emitting diodes, particularly as emissive layers. This study also led to an understanding about the dependence of their mesomorphism (mesophase type, stability and thermal range) and photophysical features on the number and pattern of their peripheral substitution, in comparison to the analogous columnar liquid crystalline TSANs reported earlier.
- Achalkumar, Ammathnadu S.,Veerabhadraswamy,Hiremath, Uma S.,Rao, Doddamane S. Shankar,Prasad, Subbarao Krishna,Yelamaggad, Channabasaveshwar V.
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p. 291 - 305
(2016/05/24)
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- Tuning the thermotropic properties of liquid crystalline p-substituted aroylhydrazones
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The synthesis and mesomorphic properties of forty substituted aroylhydrazones with peripheral mono-, di- and tri- alkoxy chains derived from a p-amino aroylhydrazone core are described. The compounds with two side chains exhibited a smectic A phase, while the compounds with six soft alkoxy side chains at symmetrical positions formed a rectangular columnar mesophase. The structures of these mesophases were confirmed by differential scanning calorimetry (DSC) analysis, polarized optical microscopy (POM) and powder X-ray diffraction (XRD) studies. Raman studies with the help of density functional theory on some of the mesogenic members have been performed to understand the changes in the intermolecular interactions during phase transitions. A structure-property relationship has been deduced, and mesogenic properties are found to be dependent on the chain length, density and position of the alkoxy chains around the molecular core.
- Singh, Hemant Kumar,Singh, Sachin Kumar,Nandi, Rajib,Singh, Madan Kumar,Kumar, Vijay,Singh, Ranjan K.,Rao, D. S. Shankar,Prasad, S. Krishna,Singh, Bachcha
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p. 44274 - 44281
(2015/06/02)
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- Benzylidenehydrazine based room temperature columnar liquid crystals
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We report on the synthesis and investigation of self-assembly properties of new benzylidenehydrazine based compounds, namely N-(2,3,4- tridodecyloxybenzylidene)-3,4,5-N′-trialkoxybenzoylhydrazines. They were confirmed to exhibit wide ranges of room temper
- Shanker,Prehm,Yelamaggad,Tschierske
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supporting information; experimental part
p. 5307 - 5311
(2011/12/15)
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- Liquid-crystalline complexes of palladium(II) and platinum(II) with di- and tri-alkoxystilbazoles: Ligand control of mesomorphism
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Liquid-crystalline complexes of palladium and platinum are formed when the metals are complexed to stilbazoles (4-styrylpyridines) bearing either two or three alkoxy chains. The complexes, termed polycatenar, show smectic C mesophases for most 3,4-disubstituted ligands, while the use of trisubstituted ligands leads to complexes showing columnar organisation, demonstrating that the spatial organisation of the metals in the liquid-crystal mesophase can be rather readily controlled. Complexes of these di- and tri-substituted stilbazoles with a cis-dicarbonylchloroiridium(I) fragment were not liquid crystalline.
- Donnio, Bertrand,Bruce, Duncan W.
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p. 2745 - 2755
(2007/10/03)
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- MULTI-NUCLEAR PALLADIUM ORGANYLS-NOVEL STRUCTURES AND PROPERTIES OF DISC-LIKE METALLOMESOGENS
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The first non-calamitic/disc-shaped metal organyl series 3 and 6 containing two or even four palladium atoms and eight or twelve flexible side chains presented here have been synthetized via the novel roof-shaped/bent dimers 2 or (the thermomesomorphic) 5
- Praefcke, Klaus,Singer, Dirk,Guendogan, Bilgi
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p. 181 - 195
(2007/10/02)
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