- Quinolines by three-component reaction: Synthesis and photophysical studies
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The synthesis of five quinolines 8-octyloxy-4-[4-(octyloxy)phenyl]quinoline and 6-alkoxy- 2-(4-alkoxyphenyl)-4-[(4-octyloxy)aryl]quinolines are described by three-component coupling reaction mediated by Lewis acid FeCl3 and Yb(OTf)3. 4-n-octyloxybenzaldehyde, anisaldehyde, 4-n-octyloxyaniline p-anisidine, and 1-ethynyl-4-heptyloxybenzene, 1-ethynyl-4-octyloxybenzene and 2-ethynyl-6-heptyloxynaphthalene are the reagents in this protocol. A Yb3+ catalyst resulted in higher yields of quinolines than Fe3+. Polarizing optical microscopy (POM) revealed that none of the quinolines were liquid crystals, even the more anisotropic. UV-Vis measurements of one of the quinolines in polar solvent show two absorption bands at 280 and 350 nm related to π,π?and n,π?transitions. No changes were observed to lower-energy absorption band (ε 4 mol L-1 cm-1) related to n,π?transition. A laser flash photolysis study for one of the quinolines relates a main transient band at 450 nm with a lifetime of 2.6 μs in ethanol, which is completely quenched in the presence of oxygen. This transient band was assigned to triplet-triplet absorption of one of the quinolines, which is semi-oxidised in the presence of phenol. Radiative rate constants have been determined along singlet and triplet excited state energies (3.39 and 3.10 eV, respectively). The chemical structure of one of the quinolines was also unequivocally confirmed by single-crystal X-ray analysis.
- Sales, Eric S.,Schneider, Juliana M. F. M.,Santos, Marcos J. L.,Bortoluzzi, Adailton J.,Cardoso, Daniel R.,Santos, Willy G.,Merlo, Aloir A.
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p. 562 - 571
(2015/03/14)
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- The effect of position of (S)-2-octyloxy tail on the formation of frustrated blue phase and antiferroelectric phase in Schiff base liquid crystals
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Two series of chiral salicylaldimine-based liquid crystals which differ from each other in the position of the (S)-2-octyloxy tail have been synthesized and characterized by polarizing optical microscopy, differential scanning calorimetry, and electrical
- Huang, Chiung-Cheng,Hsu, Ching-Chung,Chen, Li-Wen,Cheng, Yu-Lun
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p. 9343 - 9351
(2015/02/19)
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- Liquid crystalline properties of dimers having o-, m- and p- positional molecular structures
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With the objective to design and synthesis of Schiff's base symmetrical liquid crystal dimmers and to study the effect of molecular structure variation (o-ortho, m-meta, p-para) and change in alkoxy terminal chain length on mesomorphic properties of liquid crystals, We have synthesized Schiff base dimers from dialdehyde derivative containing 2-hydroxy-1,3-dioxypropylene as short spacer with aniline derivatives having different lengths of terminal alkoxy chains (n = 5, 7, 9). The chemical structure of the final products was characterized by proton nuclear magnetic resonance (1H NMR) spectroscopy and fourier transform infrared (FT-IR) spectroscopy. The mesomorphic properties and optical textures of the resultant dimers were characterized by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The existence of smectic A phase transition was confirmed by the observation of batonnets and fan shaped textures in optical microscopy when compound were heated from crystalline phase. All of the dimers of this series, with the exception of 2S5 -ortho, -meta, -para, were thermotropic liquid crystal. The compound 2S9 -meta was monotropic, while the rest were enantiotropic. It was found that the change in terminal alkoxy chain length has pronounced effect on the mesomorphic properties. The temperature range of smectic A phase window widens with increasing alkoxy chain length.
- Park, Joo-Hoon,Choi, Ok-Byung,Lee, Hwan Myung,Lee, Jin-Young,Kim, Sung-Jo,Cha, Eun-Hee,Kim, Dong-Hyun,Ramaraj,So, Bong-Keun,Kim, Kyung-Hwan,Lee, Soo-Min,Yoon, Kuk Ro
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experimental part
p. 1647 - 1652
(2012/07/27)
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- Liquid-crystalline polymorphism of 4-heptyloxybenzylidene-4′- alkyloxyanilines and their phase equilibrium with 4-octyloxyphenyl 4-nitrobenzoate
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This paper describes the synthesis and liquid-crystalline properties of the homologous series of 4-heptyloxybenzylidene-4′-alkyloxyanilines (7-n). Six of them are presented for the first time. Based on the polarization microscopy (POM and TOA methods) and the calorimetric (DSC) measurements following polymorphism has been detected: nematic, smectic C and smectic I mesophases. The presence of these mesophases was confirmed by the miscibility method, using 4-octyloxyphenyl 4-nitrobenzoate and terephtal-bis (4-butyloaniline) as a mesophase references. Extraordinary results have been found in the mixtures of the investigated compounds with 4-octyloxyphenyl 4-nitrobenzoate; Induced smectic A has been observed, which is connected with very strong intermolecular interactions. Additionally destabilization of nematic and smectic C phases was visible.
- Godzwon, Joanna,Sienkowska, Monika J.,Galewski, Zbigniew
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scheme or table
p. 75 - 82
(2012/04/04)
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- The synthesis and NLO properties of 1,8-naphthalimide derivatives for both femtosecond and nanosecond laser pulses
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Four 1,8-naphthalimide derivatives were synthesized for new nonlinear optical(NLO) materials. Hydrazone group as a p-π structure was introduced into the molecule to extend conjugation and produce NLO properties. Their linear and nonlinear optical (NLO) properties were studied in details. The results show that these compounds possess strong excited-state absorption (ESA) properties and optical limiting with nanosecond laser pulses at 532 nm. Moreover, they also preserve the luminescence originated from naphthalimide and two-photon absorption (TPA) behaviour which can be observed under femtosecond laser pulses ranged from 750 to 870 nm. The broad-band optcial limiting properties of these compounds indicate that they can be potentially applicated in optical limiting materials.
- Ye, Gao-Jie,Zhao, Ting-Ting,Jin, Zheng-Neng,Gu, Pei-Yang,Mao, Jia-Yuan,Xu, Qing-Hua,Xu, Qing-Feng,Lu, Jian-Mei,Li, Na-Jun,Song, Yin-Ling
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scheme or table
p. 271 - 277
(2012/05/04)
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- Synthesis of symmetric liquid crystal dimers based on azo and imine groups and investigation of phase behaviour by varying alkoxy terminal chain length
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With the objective to study the effect of alkoxy terminal chain length on mesomorphic properties of liquid crystals, we have synthesized two (Azo and Imine) different series of dimesogens by varying terminal alkoxy chain length (n = 6-12) with a short spacer unit in between two mesogens. Transition temperatures and phase characterization were studied by DSC, POM and XRD analysis. It was found that all the dimers show mesomorphic properties and the change in terminal alkoxy chain length has pronounced effect on the smectic phase window. In the DSC cooling scan, the smectic phase window of azo compounds increased from 6.4°C (2A6) to 16.0°C(2A12), whereas in Schiff base compounds, it increased from 9.2°C (2S6) to 31.0°C(2S12). Further, the 2A11 dimer was found to undergo photo induced configurational changes.
- Kim, Tae Hyeong,Lee, Chang Sin,Ramaraj,Jeon, Hye Jin,Song, Hyun Hoon,Lee, Soo Min,Yoon, Kuk Ro
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experimental part
p. 102 - 116
(2010/03/04)
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- Synthesis and liquid crystalline properties of novel triazene-1-oxide derivatives
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A new group of compounds, C6H5-N(O)=N-NH-C6H4-C(O)-O-C6H4-CH=N-C6H4-OR, (1), [R=n-alkyl group; 1a (R=C7H15 ) to 1h (R=C14H29)], has been designed and synthesized to develop triazene-1-oxide based liquid crystals. All the compounds have been characterized on the basis of their spectral data. Their thermal behavior has been examined and found to exhibit thermotropic liquid crystalline behavior over a wide range of temperature. All members of this family uniformly show nematic phase behavior on melting up to the clearing point during heating as well as on phase entering up to the solidification during cooling. An odd-even effect on transition temperatures has been observed during heating as well as cooling.
- Das, Purak,Biswas, Achintesh Narayan,Bandyopadhyay, Pinaki,Mandal, Pradip Kumar
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scheme or table
p. 3 - 15
(2010/03/24)
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- Smectic polymorphism of 4-nonyloxybenzylidene-4′-alkyloxyanilines
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This paper describes liquid-crystalline polymorphism of the homologous series of 4-nonyloxybenzylidene-4′-alkyloxyanilines. Based on the polarization microscopy (POM, TOA) and the calorimetric (DSC) measurements the following mesophases were detected: nematic, smectic A, smectic C, smectic B, smectic I and smectic G. The presence of these mesophases was confirmed by the miscibility method, using: 4-heptyloxybenzilidene-4′-pentylaniline, 4-hexyl-4′-decyloxyazobenzene and 4-nonyloxybenzilidene-4′-butylaniline as mesophase references. Influence of the alkyl chain length on the type of mesophases and entropic effects of phase transition are discussed.
- Godzwon, Joanna,Sienkowska, Monika J.,Galewski, Zbigniew
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p. 259 - 267
(2008/03/13)
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- EFFECT OF THE REVERSAL OF THE CENTRAL SCHIFF'S BASE LINKAGE ON LIQUID CRYSTAL PROPERTIES: THE 4-PHENYLBENZYLIDENE-4 prime -n-ALKOXYANILINES AND 4-(4 prime -n-ALKOYXBENZYLIDENEAMINO)-BIPHENYLS.
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Twelve 4-phenylbenzylidene-4 prime -n-alkoxyanilines were prepared and their liquid crystal phases categorized. The properties of these compounds are compared with those of the analogous Schiff's bases, the 4-(4 prime -n-alkoxybenzylideneamino)biphenyls,
- Byron,Keating,O'Neill,Wilson,Goodby,Gray
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p. 179 - 192
(2007/10/02)
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