Indian Association for the Cultivation of Science

About: Indian Association for the Cultivation of Science is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Catalysis & Excited state. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

Microwave-assisted simple and efficient ligand free copper nanoparticle catalyzed aryl-sulfur bond formation

Abstract: A new protocol for the coupling of aryl iodides with thiophenols and alkanethiols catalyzed by copper nanoparticles under ligand-free condition has been developed A variety of functionalized aryl sulfides are prepared in excellent yields under microwave irradiation for 5-7 min A plausible radical mechanism has been suggested

Large magnetic cooling power involving frustrated antiferromagnetic spin-glass state in R 2 NiSi 3 ( R = Gd , Er )

Abstract: The ternary intermetallic compounds ${\mathrm{Gd}}_{2}{\mathrm{NiSi}}_{3}$ and ${\mathrm{Er}}_{2}{\mathrm{NiSi}}_{3}$ are synthesized in chemically single phase, which are characterized using dc magnetization, ac magnetic susceptibility, heat capacity, and neutron diffraction studies. Neutron diffraction and heat capacity studies confirm that long-range magnetic ordering coexists with the frustrated glassy magnetic components for both compounds. The static and dynamical features of dc magnetization and frequency-dependent ac susceptibility data reveal that ${\mathrm{Gd}}_{2}{\mathrm{NiSi}}_{3}$ is a canonical spin-glass system, while ${\mathrm{Er}}_{2}{\mathrm{NiSi}}_{3}$ is a reentrant spin cluster-glass system. The spin freezing temperature merges with the long-range antiferromagnetic ordering temperature at 16.4 K for ${\mathrm{Gd}}_{2}{\mathrm{NiSi}}_{3}$. ${\mathrm{Er}}_{2}{\mathrm{NiSi}}_{3}$ undergoes antiferromagnetic ordering at 5.4 K, which is slightly above the spin freezing temperature at 3 K. The detailed studies of nonequilibrium dynamical behavior, viz., the memory effect and relaxation behavior using different protocols, suggest that both compounds favor the hierarchical model over the droplet model. A large magnetocaloric effect is observed for both compounds. Maximum values of isothermal entropy change $(\ensuremath{-}\mathrm{\ensuremath{\Delta}}{S}_{M})$ and relative cooling power (RCP) are found to be 18.4 J/kg K and 525 J/kg for ${\mathrm{Gd}}_{2}{\mathrm{NiSi}}_{3}$ and 22.6 J/kg K and 540 J/kg for ${\mathrm{Er}}_{2}{\mathrm{NiSi}}_{3}$, respectively, for a change in field from 0 to 70 kOe. The values of RCP are comparable to those of the promising refrigerant materials. A correlation between large RCP and magnetic frustration is discussed for developing new magnetic refrigerant materials.

Recent advances in carbon quantum dot-based sensing of heavy metals in water

Abstract: A diverse range of materials (e.g., metallic nanoparticles, semiconductor oxides, composites, polymers, and MOFs) have been reported for sensing applications in water samples based on several transduction techniques (e.g., absorbance, fluorescence, Raman, colorimetry, voltammetry, and plasmon resonance). Recently, carbon quantum dots (CQDs) have gained significant interest as fluorescent and small carbonaceous nanostructures for designing sensing devices (either as-produced or through modification) for heavy metals due to their excellent properties (e.g., photostability, facile surface modification, optical tunability, and environmental friendliness). This review provides a comprehensive overview on the role of CQDs as sensors for heavy metals in water. This work will help open up opportunities for the use of CQDs under the diverse field conditions.

Templateless Synthesis of Polygonal Gold Nanoparticles: An Unsupported and Reusable Catalyst with Superior Activity

Abstract: We report the synthesis of polygonal gold nanoparticles (GNPs) by an in situ reduction technique using ferric ammonium citrate as reducing agent in absence of any surfactant or polymeric template. Transmission electron microscopic analysis and selected area electron diffraction patterns confirmed the formation of well-crystalline polygonal GNPs grown preferentially along the (111) direction, which is consistent with the results of X-ray diffractometry analysis. The results of control experiments of HAuCl4 with tri-ammonium citrate in presence of different externally added metal ions like Fe3+, Ni2+, Cu2+, Zn2+, and Al3+ suggested the ion-induced growth mechanism in the formation of polygonal GNPs. The purified polygonal GNPs were then successfully used as catalyst in the borohydride reduction of three isomeric nitrophenols and also in the aerobic oxidation of different D-hexoses (e.g., D-glucose, D-mannose, D-fructose). The catalytic activity of these polygonal GNPs is higher by a factor of 300–1000, depending on the GNP's sample type, in nitrophenol reduction compared to that of spherical GNPs. Similar activity enhancement was also observed in the aerobic oxidation of different D-hexoses. These polygonal GNPs catalyst are very stable and could be reused several times in the borohydride reduction of nitrophenols without much losing in their virgin catalytic activity.