Publications by authors named "Mohan Das Thangamuthu"

In this report, the design and synthesis of cholesterol-based sugar azobenzene derivatives as photo-responsive organogelators have been carried out. The gel formation in different solvents was examined, and a minimum CGC of 0.5 % (w/v) was attained in toluene.

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Phase-selective gelation of low molecular-weight photoresponsive organogelator possessing long aliphatic chain azobenzene sugar derivatives and its applications in the recycling of aromatic solvents and also the removal of cationic dyes is reported. Very low critical gelation concentration (CGC) in aromatic solvents implies that it acts as a very good gelator. The photoinduced gel-to-sol transition was attained by irradiation with UV light at 350 nm.

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Simple, effective, and eco-friendly sugar-based phase-selective gelators were synthesized at a low cost. They showed high gelling ability toward a wide range of solvents at lower concentrations (minimum gelation concentration ∼0.3%).

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Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) - commonly known as the "click reaction" - serves as the most effective and highly reliable tool for facile construction of simple to complex designs at the molecular level. It relates to the formation of carbon heteroatomic systems by joining or clicking small molecular pieces together with the help of various organic reactions such as cycloaddition, conjugate addition, ring-opening, etc. Such dynamic strategy results in the generation of triazole and its derivatives from azides and alkynes with three nitrogen atoms in the five-membered aromatic azole ring that often forms gel-assembled structures having gelating properties.

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The synthesis of 3,4,5-tri-O-benzohydrazide based N-glycosylamines were characterized using NMR (H and C) and mass spectral analysis. Gelation properties of the synthesized molecules in different solvents and oils were studied and gelation was observed with minimum Critical Gelator Concentration (CGC) of 0.8% (w/v) in benzene.

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A concise pathway to synthesize a novel class of nine different pyrido(2,3-d)pyrimidine-C-β-d-glycosides is reported. Formation of Michael adduct as an intermediate followed by heterocyclization are the key steps and the products were characterized by different spectral studies. β-Anomeric forms of C-glycosides were assigned from 1H NMR spectroscopy.

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Facile one-pot synthesis of biphenyl methyl-C-β-D-glycosides was carried out using 4,6-O-protected-C-glycoside, aromatic aldehydes and malononitrile in pyrrolidine as an organocatalyst. Studies reveal that the use of pyrrolidine resulted in a better yield.

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An efficient one-pot synthesis of novel sugar based dispirooxindolo-pyrrolidines/pyrrolizidines has been accomplished by a [3+2]-cycloaddition. This method utilizes an azomethine ylide derived from isatin and sarcosine/l-proline, with an ether linked α-,β-unsaturated-β-C-glycosidic ketones as the dipolarophile. All these sugar-based heterocyclics were characterized by NMR ((1)H and (13)C) and elemental analysis.

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A novel class of six different triaryl pyridine N-glycosylamine amphiphiles was synthesised and characterized based on different spectral techniques, such as NMR and mass analysis. Gelation properties in different aromatic and aliphatic solvents were studied and gelation was observed predominantly in aliphatic solvents with CGC of 0.5% (w/v) and is attributed to the presence of long alkyl chain.

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Copper catalyzed azide-alkyne cycloaddition reaction (CuAAC) of non-fluorescent coumarin azides and sugar terminal alkynes afforded intense fluorescent 1,2,3-triazoles in 75-85% of yield. The photophysical properties of coumarin-sugar triazoles influenced greatly, upon introducing different substituents at 6th and 7th positions. The experimental observations were further supported by TD-DFT computational studies.

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Facile glycosylation of a fluorescein diol derivative with per-O-acetyl/benzoyl sugar derivatives using BF(3)·Et(2)O catalyst resulted in the formation of the expected glycosides in 54-66% yield. The biological screening of the glycosides against different microbes shows good inhibitory activity. The antioxidant activity of the fluorescein-based glycosides shows remarkable inhibition (IC(50) ∼80%).

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A facile synthesis of sugar-pyrazole derivatives has been accomplished by condensation of sugar-chalcone with hydrazine hydrate under neutral conditions resulting in yields of 70-85%. The products are characterized by FTIR and NMR spectroscopy and by elemental analysis. The β-anomeric forms for these derivatives were assigned by NMR spectroscopy.

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