Synthesis and mesogenic properties of a novel family of oligothiophene derivatives

With the aim of developing new oligothiophene-based liquid crystals involving hydrogen bonding, new terthiophene derivatives containing an alkylamide group, N,N'-distearyl-2,2' : 5',2"-terthiophene-5,5"-dicarboxamide (DNC₁₈3T) and N,N'-dialkyl-5,5"-dibromo-2,2' : 5',2"-terthiophene-4,4"-dicarboxamides (DNC_nDBr3T, n = 5, 8, 16, 18), were designed and synthesized, and their thermal behaviour examined. While DNC₁₈3T did not exhibit liquid crystallinity, DNC_nDBr3T compounds with n = 8, 16, 18 were found to form smectic A phases. In addition to liquid crystal behaviour, crystal polymorphism was also observed for DNC₁₆DBr3T. It is shown that both the position of the amido group and the alkyl chain length greatly affect liquid crystal phase formation. The absence of liquid crystallinity in the corresponding ester derivatives suggests that intermolecular hydrogen bonding also plays a role in the formation of liquid crystal phases in the DNC_nDBr3T system.     

Synthesis and liquid crystal properties of a novel family of oligothiophene derivatives

In order to develop novel oligothiophene-based liquid crystals capable of hydrogen bonding, new terthiophene derivatives containing an alkylamide group, N,N′-dialkyl-5,5″-dichloro-2,2′:5′,2″-terthiophene-4,4″-dicarboxamide (DNC_nDCl3T, n=8, 18), N,N′-dialkyl-5,5″-dibromo-2,2′:5′,2″-terthiophene-4,4″-dicarboxamide (DNC_nDBr3T, n=5, 8, 16, 18), or N,N′-dialkyl-5,5″-diiodo-2,2′:5′,2″-terthiophene-4,4″-dica-rboxamide (DNC_nDI3T, n=8, 18), were designed and synthesized, and their thermal behaviour was examined. It was found that DNC₁₈DCl3T, DNC₁₈DI3T and DNC_nDBr3T (n=8, 16, 18) form a smectic A phase and that the alkyl chain length greatly affects liquid crystal phase formation. The absence of liquid crystallinity in the corresponding ester derivatives suggests that intermolecular hydrogen bonding also plays a role in the formation of a liquid crystal phases in the DNC_nDBr3T system.     

Synthesis and properties of a novel family of fluorous triphenylphosphine derivatives

A novel approach to the preparation of perfluorotail-functionalized triarylphosphines using a p-silyl substituent as the branching point has been developed. This approach enabled the attachment of between three and nine perfluorotails per phosphorus atom, resulting in the production of highly fluorous tris[p-(1H,1H,2H, 2H-perfluoroalkylsilyl)aryl]phosphines, P[C(6)H(4)-p-SiMe(3)(-)(n)()(CH(2)CH(2)C(x)()F(2)(x)()(+1))(n)()](3) (n = 1, 2, 3; x = 6, 8), containing between 50 and 67 wt % fluorine. (31)P NMR studies indicate that the phosphorus atoms, and consequently the sigma-donor and pi-acceptor properties of these phosphines, are not influenced by the electron-withdrawing perfluoroalkyltails. The fluorous triarylphosphines are readily soluble in fluorous solvents and display fluorous phase preference in several fluorous biphasic systems. The phase partitioning of these fluorous ligands, as well as their donor properties, is discussed in relation to their potential for fluorous biphasic catalyst separation.     

Synthesis and neuroprotective properties of novel cinnamide derivatives

A new series of compounds （E）-1-（4-（bis-arylmethyl）piperazin-l-yl）-3-arylprop-2-en-1-one （1a-r）, have been synthesized and their structures were confirmed by ESI-MS and 1H NMR. The preliminary pharmacological screening showed that some of these compounds had similar neuroprotective effects with Edaravone.     

Synthesis and mesogenic properties of azo-dye liquid crystals

Azo-dye liquid crystals with strong amino electro-donating and moderately flexible carboxylate electron-withdrawing groups were synthesized, and their mesogenic properties were studied.     

Synthesis of novel tri-podal mesogenic alkenes and side-chain polysiloxanes

Low molecular weight tri-podal biphenyl- and benzoate-type mesogens [C₆H₅C₆H₄O(CH₂)₅SiMe₂CH₂CH₂SiMe₂]₃CH (4), [C₁₁H₂₃O(C₆H₄)₂O(CH₂)₅SiMe₂]₃CH (5) and [MeOC₆H₄OC(O)C₆H₄O(CH₂)₅SiMe₂]₃CH (6) (C₆H₄ = 1,4-phenylene) were obtained, from branched silyl substituted methane precursors [CH₂CH(Me)₂Si]₃CH (1) and (HMe₂Si)₃CH (2). The biphenyl-containing ones (4) and (5) were converted into terminal alkenes, which were subsequently hydrosilylated with poly(methylsiloxanes). The polymer derived from (5) exhibited mesomorphic properties. Such systems have the potential to significantly increase the density of liquid crystal rod-like structures in side chains of linear polymers (or dendritic liquid crystal polymers).     

Synthesis and properties study of novel ferrocenyl isoxazole derivatives

A synthetic procedure based on the 1,3‐dipolar cycloaddition reactions of nitrile oxides and ethynylferrocene derived from ferrocene has been developed to synthesize new ferrocenyl‐isoxazole derivatives. The stable solids were thoroughly characterized by ¹H NMR, FT‐IR, and mass spectroscopy. The structure of (η⁵‐C₅H₅) Fe (η⁵‐C₅H₄) C₃HNOC₆H₄CH₃ was determined by single‐crystal X‐ray diffraction. The electrochemical behaviors of the synthesized ferrocenyl‐isoxazole derivatives were also studied. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis and anti-inflammatory properties of novel 1,2,4-triazole derivatives

This research is based on the pharmacological activity of the triazole ring. In the last decade much work has been conducted on the triazole ring. Scientists have developed many new compounds based on this structure and screened them to obtain molecules with good pharmacological activity. In this research starting from 4-amino-5-(4-chlorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione, a series of new 1,2,4-triazole derivatives were prepared. Results revealed that two compounds had anti-inflammatory potency after 4 h greater than that of indomethacin whereas another derivative had less potency than indomethacin.     

An investigation of the mesogenic properties of dibenzoquinoxaline derivatives

The syntheses of two new discotic molecules based on the dibenzoquinoxaline core are reported; comparison of their phase behaviors to a known dinitrile compound demonstrates the importance of specific functional groups in stabilizing columnar mesophases.     

Synthesis and liquid crystalline properties of novel pyridine derivatives

The treatment of 4‐hydroxypyridine with cholestery p‐(ω‐bromoalkyloxy)benzoates in N,N‐dimethylformamide containing K₂CO₃ gave cholestery p‐[ω‐(4‐pyridyloxy)alkyloxy]benzoates, which exhibited liquid crystalline properties     

线型和星型平面噻吩类低聚物衍生物分子结构及光电性质研究

运用密度泛函DFT B3LYP／6-31G(d)方法对线型(a)和星型(b)平面噻吩类低聚物衍生物分别进行了几何构型优化,并采用含时密度泛函TD-DFT B3LYP／6-31G(d)方法计算了其紫外吸收光谱．计算结果表明:用TD-DFT．方法计算体系的紫外吸收光谱值与实验数据吻合;通过对噻吩类低聚物衍生物分子几何结构和前线分子轨道能级的分析,并从理论上解释了线型(a)和星型(b)衍生物光谱性质的差异:后者与前者相比较吸收光谱发生红移,这是由于星型结构使其相应HOMO能级升高,电离能(IP)降低,成为很好的电子给体和空穴传输材料．     

Synthesis and properties of three novel series of monomers containing para-methoxyazobenzene as the mesogenic group

Three novel series of monomers, namely n-1-bromo-[4-(4-methoxyphenylazo)phenyloxy]-alkanes (Bn, n = 3, 6, 10), n-[4-(4-methoxyphenylazo)phenyloxy]alkyloxy-4-methoxybenzene (Cn, n = 3, 6, 10) and n-[4-(4-methoxyphenylazo)phenyloxy]alkyloxy-[4-methoxy-2,5-bis(chloromethyl)]benzene (Dn, n = 3, 6, 10) were synthesized and characterized with FTIR, ¹H NMR, UV-visible and fluorescence spectroscopy. Their thermal behaviour was studied by different scanning calorimetry and polarizing optical microscopy. The results show that B3, B6 and C6 exhibit monotropic nematic liquid crystalline behaviour.     

Synthesis and properties of three novel series of monomers containing para-methoxyazobenzene as the mesogenic group

Three novel series of monomers, namely n-1-bromo-[4-(4-methoxyphenylazo)phenyloxy]-alkanes (Bn, n = 3, 6, 10), n-[4-(4-methoxyphenylazo)phenyloxy]alkyloxy-4-methoxybenzene (Cn, n = 3, 6, 10) and n-[4-(4-methoxyphenylazo)phenyloxy]alkyloxy-[4-methoxy-2,5-bis(chloromethyl)]benzene (Dn, n = 3, 6, 10) were synthesized and characterized with FTIR, ¹H NMR, UV-visible and fluorescence spectroscopy. Their thermal behaviour was studied by different scanning calorimetry and polarizing optical microscopy. The results show that B3, B6 and C6 exhibit monotropic nematic liquid crystalline behaviour.     

Synthesis and mesomorphic properties of a novel ladder-like 1,4-phenylene-bridged liquid crystalline polysiloxane containing ester-based mesogenic side groups

A new ladder-like 1,4-phenylene-bridged liquid crystalline polysiloxane bearing ester-based mesogenic side groups, LPLCPS, has been synthesized by hydrosilylation of a SiH-terminated ester-based mesogen compound (1) with a ladder-like 1,4-phenylene-bridged polyvinylsiloxane (LPPVS) containing vinyl-terminated side groups in the presence of dicyclopentadienylplatinum(II) chloride (Cp₂PtCl₂) catalyst. Compound 1 was synthesized by hydrosilylation of 1,1,3,3-tetramethyldisiloxane (HMM) with the vinyl-terminated ester-based mesogenic compounds. Various characterization methods including FTIR, ¹H NMR, ¹³C NMR, ²⁹Si NMR, polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction were used and the results combined to demonstrate that LPLCPS shows thermotropic smectic mesomorphic behaviour with a high clearing point and a wide mesophase range.     

Synthesis,mesogenic and dielectric properties of fluorosubstituted isothiocyanatoterphenyls

The synthesis, mesomorphic and physical properties of 14 homologous series of laterally fluorinated 4?-alkyl-4-isothiocyanatoterphenyls were described. Influence of the number of fluorine atoms and their position in the terphenyl core on the phase transition temperatures, nematic range, dielectric and optic anisotropy as well as bulk viscosity were discussed. The compounds with the most optimal properties for formulation of nematic mixtures were selected, and mixture examples with low viscosity and medium or high birefringence were presented.     

Synthesis, characterization and FET properties of novel dithiazolylbenzothiadiazole derivatives

Dithiazolylbenzothiadiazoles easily obtained have high electron affinity and the FET device of a trifluoromethylphenyl derivative exhibited a good n-type performance with high electron mobility.     

Synthesis and properties of novel pyrazolopyrimidine derivatives containing sulfur atom

A series of new pyrazolopyrimidine derivatives containing sulfur atom 5 has been designed and synthesized by treatment of carbodiimide 3 , which came from iminophosphorane 2 undergoing a aza‐Wittig reaction with phenyl ioscyanate, with alkylamine. The structures of compounds 5 were confirmed by ¹H NMR, IR, EI‐mass spectroscopy, and elemental analysis. The results of preliminary bioassay indicate that most compounds 5 exhibit an inhibition effect against Cercospora beticola, Botryosphaeria berengeriana, and Pellicularia sasakii, and compound 5g shows 91.2% inhibitory rate to root of rape and the other less than 50% at 100 mg/l. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:333–337, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20024     

Synthesis and thermal properties of diurethanes containing various mesogenic units

Abstract

Five homologous series of diurethanes containing mesogenic moieties were synthesized by addition reactions of ω-alkenols to aromatic diisocyanates. The thermal behaviour of the compounds was studied by differential scanning calorimetry and on the hot stage of a polarizing microscope. Thermotropic liquid crystal behaviour was found for the diurethanes having a central core of more than two aromatic rings. Smectic C mesophases were observed for the derivatives of 4,4″-p-terphenylene and nematic mesophases for the diurethanes containing a di(4-phenylene)terephthalate unit. The compounds of both series possess high transition temperatures and narrow mesomorphic ranges.     

Synthesis and fluorescence properties of novel benzo[a]phenoxazin-5-one derivatives

Thirteen, benzo[a]phenoxazin-5-one derivatives 3a-m were synthesized from 4-nitrosoaniline hydrochlorides 1a-m and ethyl 1,3-dihydroxynaphthoate 2 and their fluorescence properties were discussed in terms of the electronic effect of substituents. A coupling reaction was carried out with 6-carbethoxy-9-N-(2-hydroxyethyl)-N-methylamino-5H-benzo[a]phenoxazin-5-one (3k) and acetyl-DL-alanine to afford N-[(6-carbethoxy-5-oxo-5H-benzo[a]phenoxazin)-9-yl]-N-methylaminoethylene acetyl-DL-alanine ester (4).