Thangamuthu Mohan Das

Synthesis and Properties of Amphiphilic Photoresponsive Gelators for Aromatic Solvents

A sugar-based photoresponsive supergelator, N-glycosylazobenzene that shows selective gelation of aromatic solvents is described. The partial trans-cis isomerization of the azobenzene moiety allows photoinduced chopping of the entangled gel fibers to short fibers, resulting in controlled fiber length and gel-sol transition. The gelator is useful for the selective removal of toxic aromatic solvents from water.

Design, synthesis and gelation studies of 4,6-O-butylidene-α,β-unsaturated-β-C-glycosidic ketones: application to plant tissue culture

A series of α,β-unsaturated-β-C-glycosidic ketones was synthesized starting from D-glucose in three steps. 4,6-O-Butylidene-β-C-glycosidic ketones on aldol condensation with aromatic and heteroaromatic aldehydes in the presence of a suitable organocatalyst led to the stereoselective formation of the products in good yield. Hydrogen bonding and π–π stacking of these derivatives were established by single-crystal XRD. The soft material derived from this method had a diameter of 10–200 nm with a three-dimensional network, as determined by SEM and HR-TEM. In the present study, we discuss the mechanism of formation of these self-assembled nanostructures, the morphology of the soft material and its thermal stability. We also demonstrate the utility of these soft materials in the field of plant tissue culture.

A sugar–pyrene-based fluorescent gelator: nanotubular architecture and interaction with SWCNTs

A sugar–pyrene-based fluorescent gelator was synthesised and characterized based on different spectral techniques. The weak interactions that exist between the pyrene moieties are responsible for gelation, which is absent in case of functionalised SWCNTs.

Design and synthesis of sugar-triazole low molecular weight gels as mercury ion sensor

A series of gel forming symmetrical bis-sugar-triazoles has been developed for the recognition of Hg2+ ions. Preferential interaction of Hg2+ ions with organogelator based chemosensor 3f led to changes in the morphology as evidenced from FESEM and HRTEM analysis.

Synthesis and antioxidant activity of a novel class of 4,6-O-protected O-glycosides and their utility in disaccharide synthesis

BF(3).Et(2)O-catalysed O-glycosylation of 1,2,3-tri-O-acetyl-4,6-O-butylidene- and ethylidene-beta-d-glucopyranose with different aliphatic and aromatic alcohols proceeds for the most part with complete retention of anomeric configuration. Antioxidant activity of O-glycosides shows significant inhibition (IC(50) approximately 77%). 1,3-Dipolar cycloaddition of terminal alkyne derivatives of O-glycosides with glycosyl azide results in disaccharides.

Protecting group/halogen effect of N-glycosylamines on the self assembly of organogelator

A series of N-glycosylamine based organogelators were synthesised from three different 4,6-O-protected saccharides. All these compounds were characterized using different spectral techniques. The effect of substituents present in the N-glycosylamines on gelation was studied from NMR and computation. Among the eighteen different gelators studied, 3b, bearing fluorine as a substituent, was observed to gelate at very low concentrations (CGC: 1%). Further, it is revealed that dipole–dipole interactions play an important role in the case of N-glycosylamine-based gelators. The presence of π–π stacking and H-bonding, as inferred from the reported X-ray diffraction data, are responsible for the gelation. Various possible modes of interaction are identified from computational studies. The gelation properties of these compounds were studied with regard to their molecular structure by scanning electron microscopy, differential scanning calorimetry, FT-IR and NMR studies.

Regioselective facile one-pot Friedländer synthesis of sugar-based heterocyclic biomolecules.

Regioselective facile one-pot synthesis of 16 different sugar-based quinoline, naphthyridine, and xanthone derivatives is reported. The compounds are characterized by NMR spectroscopy and elemental analysis. The beta-Anomeric form of the sugar moiety was identified from (1)H NMR studies. Antimicrobial studies of these sugar-heterocyclic derivatives, 3a, 3b, 3f, 5c, 7a, 7b, and 7c show excellent activity against different microbes.

FACE-selective fluorogenic cycloaddition reaction between coumarin azides and sugar terminal alkynes: an experimental and computational study

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.

Design, synthesis, and biological evaluation of a novel class of fluorescein-based N-glycosylamines.

A series of fluorescein-based N-glycosylamines was synthesized from the corresponding fluorescein amine and a partially protected d-glucose. The physiochemical investigation of these compounds by spectral and morphological studies reveals their gelation potential. The exclusive localization of fluorescence in the cytoplasm through cell imaging studies reveals the anti-cancer potentials of N-glycosylamines.

A facile synthesis of sugar-pyrazole derivatives.

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.