- The effect of hydrogen bonding and azomethine group orientation on liquid crystal properties in benzylidene aniline compounds
-
This study examines the effects of substituents and hydrogen bonding, orientations of imine linkage on the behavior of benzylidene aniline compounds as liquid crystals (LC). Compounds 4-carboxy benzylidene-4-X-aniline (X = H, F, Cl, Br, CH3, OCH3) 1a-6a were synthesized by the reaction of aniline and its substituted derivatives with 4-formylbenzoic acid. Compounds 4-X-benzylidene-4-carboxy aniline (X = H, F, Cl, Br, CH3, OCH3) 1b-6b were synthesized by the reaction of benzaldehyde and its substituted derivatives with 4-aminobenzoic acid using absolute ethanol as the solvent. Synthesized compounds were characterized by FT IR and 1H NMR spectroscopy, liquid crystal properties were investigated using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) techniques. Based on the mesomorphic properties, it was proven that the compounds 2b-4b are dimorphic exhibiting a smectic and nematic phase, compounds 5b, 6b are monomorphic exhibiting a nematic phase, while compounds 1a-6a and 1b have not shown any mesophase. For compounds 1a-6a hydrogen bonding and reversing imine linkage (in comparison with compounds 1b-6b) caused the absence of their mesomorphic properties.
- Kshash, Abdullah Hussein
-
p. 739 - 747
(2020/10/02)
-
- Synthesis of 4-imino-2H,3H,5H-[1,2,5]thiadiazolidin-1-oxide through cycloaddition reaction of N-sulphinylanilines and N-(α-cyano-α-aryl) -methylanilines
-
Through the normal mode of cycloaddition reaction of N-(α-cyano- α-aryl)-methylanilines (II) onto N-sulphinylanilines (III) has provided 2,3,5-triaryl-4-imino-2H,3H,5H-[1,2,5]thiadiazolidin-1-oxides (IV). The present protocol has advantage of convenient operation to synthesize heterocyclics in good yield.
- Kaur, Manpreet,Singh, Baldev
-
p. 1157 - 1161
(2014/08/05)
-
- Synthesis of novel β-amino ketones containing a p-aminobenzoic acid moiety and evaluation of their antidiabetic activities
-
The synthesis of two series of β-amino ketones containing a p-aminobenzoic acid moiety (TM-1 and TM-2) using a modified protocol of the Mannich reaction is reported. The molecular structures of a total of tweenty three new target compounds were characterized by 1H NMR, 13C NMR, ESI-MS and HR-MS. Subsequently, their antidiabetic activities were screened in vitro. The α-glucodase inhibition (α-GI) activity of compound 1e reached a remarkable level of 66.50%. The peroxisome proliferator-activated receptor (PPAR) relative activation activities of six compounds are above 80%, and in particular 2i displays an unprecedentedly high PPAR of 130.91%. The structure-activity relationships of the compounds were established. 2i is also subject to further in-depth investigation.
- Tang, Guangxia,Yan, Jufang,Fan, Li,Xu, Jin,Song, Xiaoli,Jiang, Li,Luo, Lingfei,Yang, Dacheng
-
p. 490 - 504
(2013/07/11)
-
- Microwave-assisted, solvent-free and parallel synthesis of some novel substituted imidazoles of biological interest
-
Solvent free microwave assisted synthesis of some novel substituted imidazoles of biological interest is reported. First, primary aromatic or heteryl amine was condensed with aryl or heteryl aldehydes to afford corresponding Schiff's base. The Schiff's base further on treatment with ammonium acetate (NH4OAC) and isatin using silica gel as the solid support, yielded the corresponding aryl imidazoles. In this paper a comparative study between the developed microwave method and conventional method is described. The synthesized compounds were analyzed by physical and analytical data. The synthesized compounds were evaluated for their antibacterial, anthelmintic, short-term anticancer and antitubercular activity. All the synthesized substituted imidazoles have shown good antibacterial activity against gram negative bacterial strains Klebsiella pneumoniae and Escherichia coli and moderate to good anthelmintic activity. The synthesized imidazole derivative possessed signifi-cant cytotoxic activity against Ehrlich's ascites carcinoma (EAC) cell lines. None of the compounds exhibited prominent antitubercular activity.
- Sharma, Gyanendra Kumar,Pathak, Devender
-
experimental part
p. 375 - 380
(2011/02/25)
-
- Microwave-assisted, solvent-free, parallel syntheses and elucidation of reaction mechanism for the formation of some novel tetraaryl imidazoles of biological interest
-
The microwave assisted, solvent free, parallel syntheses of title compounds is described in this protocol. Twelve new tetraaryl imidazoles, which are incorporated with the chemotherapeutic pharmaco- phores, have been synthesized by adopting one pot multic
- Kumar, B. R. Prashantha,Sharma, Gyanendra Kumar,Srinath,Noor, Mohamed,Suresh,Srinivasa
-
experimental part
p. 278 - 284
(2009/07/05)
-
- Synthesis, spectroscopic and molecular structures investigations of some carboxylated schiff bases
-
A series of nine carboxylated Schiff bases (five of them are newly prepared viz. compounds 5-9), are prepared and characterized by various physico-chemical techniques. The molecular structures of synthesized Schiff bases are investigated by IR, UV-Visible, molar conductivities at different concentrations in two different solvents and by their pH values in ethanolic solutions.The IR spectra show absorptions due to =N⊕H- stretching and -N-H bending vibrations, the UV-Visible spectra indicates absorptions are due to protonated species. The molar conductivities, 0.1-0.6 Ω-1 cm2 mol-1, prove that these compounds are weak electrolytes and are even weaker than tyrosine and phenylalanine, 2.5-13 Ω-1 cm 2 mol-1. The melting points and pH values of Schiff bases are compared with those of some α-aminoacids and some related Schiff bases that have no COOH group in their structures. On the bases of these data, it was concluded that carboxylated Schiff bases exist in two forms, the ionized and the free base where the later is predominant. The ionized form is similar to the zwitterion of the α-aminoacid, in which a proton is transferred from COOH to the azomethine (-CHN-) group.
- Titinchi, Salam J.J.,Abbo, Hanna S.,Saeed, Ali A.H.
-
p. 121 - 126
(2007/10/03)
-
- Die Hydrolyse Schiffscher Basen - Substituenten- und Loesungsmitteleinfluss. I. Die basische Hydrolyse von 4'-Carboxy-N-(X-benzyliden)anilinen als Zweistufenreaktion in methanolisch-waessriger Loesung - Kinetik und Aktivierungsparameter
-
It is shown that the hydrolysis of some Schiff bases which were resolved in methanol previously give a two step reaction in basic medium. 35 rate constants are correlated with the Hammett's ? constants of the substituent groups, showing that linear relationship exist with ρ= -1,54 and ρ= -0,63, respectively.Activation parameters are given of both first and second step of reaction.
- Mitzner, R.,Seidel, S.
-
p. 1179 - 1185
(2007/10/02)
-