A hidden Goldstone mechanism in the Kagom\'e lattice antiferromagnet

In this paper, we study the phases of the Heisenberg model on the \kagome lattice with antiferromagnetic nearest neighbour coupling $J_1$ and ferromagnetic next neighbour coupling $J_2$. Analysing the long wavelength, low energy effective action that describes this model, we arrive at the phase diagram as a function of $\chi = \frac{J_2}{J_1}$. The interesting part of this phase diagram is that for small $\chi$, which includes $\chi =0$, there is a phase with no long range spin order and with gapless and spin zero low lying excitations. We discuss our results in the context of earlier, numerical and experimental work.Comment: 21 pages, latex file with 5 figure

Iodine/MeOH: a novel and efficient reagent system for thiocyanation of aromatics and heteroaromatics

Indoles, pyrroles, oxindoles and aromatic amino compounds undergo smooth thiocyanation with ammonium thiocyanate in the presence of molecular iodine in methanol under mild conditions to afford the corresponding 3-indolyl, 2-pyrrolyl and 4-aryl thiocyanates, respectively, in excellent yields with high selectivity. The reactions proceed rapidly at room temperature without heating or the use of strong Lewis acids

Organic synthesis in water: green protocol for the synthesis of 2-amino furan derivatives

Aldehyde, dimethyl acetylenedicarboxylate (DMAD) and cyclohexyl isocyanide undergo smooth coupling in water to produce the corresponding 2-aminofuran derivatives in good yields. Water helps to avoid the use of highly toxic and environmentally unfavorable solvents for this conversion

Novel chalcogenides of thymidine and uridine: synthesis, properties and applications

A facile and efficient methodology has been developed for the synthesis of dithymidine and di-uridine derived disulfides using benzyltriethylammonium tetrathiomolybdate as a sulfur transfer reagent. However, a similar reaction of thymidine derivative with tetraethylammonium tetraselenotungstate as a selenium transfer reagent resulted in the formation of an unexpected cyclic diselenide. The disulfide derivatives of nucleosides have been used as precursors in a tandem disulfide cleavage-Michael addition/ring opening reactions to construct aminoacid and carbocyclic derivatives of nucleosides

Ionic liquids-promoted multi-component reaction: Green approach for highly substituted 2-aminofuran derivatives

The three-component coupling of aldehyde, dimethyl acetylenedicarboxylate (DMAD) and cyclohexyl isocyanide proceeds efficiently in [bmim]BF<SUB>4</SUB> ionic medium under extremely mild conditions to afford the corresponding 2-aminofuran derivatives in high yields. The zwitterionic intermediate formed in situ from DMAD and isocyanide shows enhanced reactivity in ionic liquids, thereby reducing reaction times and improving the yields significantly. Ionic liquid helps to avoid the use of highly toxic and environmentally unfavorable benzene as solvent for this conversion. The recovered ionic liquid was reused for five to six times with consistent activity