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: Excited state & Catalysis. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

MnII/CoII-Terephthalate Frameworks Containing Dipyridine Coligands: Syntheses, Crystal Structures, Magnetic Behaviors, and Thermal Studies

Abstract: Three new metal–organic hybrid polymeric networks of CoII and MnII with the molecular formulae [Co(bpp)(tp)(H2O)2] (1), [Mn(bpds)(tp)(H2O)2]·(bpds) (2), and [Mn(4,4′-bipy)(H2O)4]·(tp) (3) (bpp = 4,4′-trimethylenedipyridine; bpds = 4,4′-bipyridyl disulfide; 4,4′-bipy = 4,4′-dipyridyl; tp = terephthalate) have been synthesized and characterized by single-crystal X-ray diffraction studies, low temperature (300–2 K) magnetic measurements, and thermal behaviors The structure determination of complexes 1 and 2 reveals a parallel interpenetrated structure of 2D layers with (4,4) topology, with metal ions at the nodes connected through tp and N,N-donor coligands The octahedral N2O4 chromophore surrounding the metal ion results from trans located tp oxygens, two water molecules, and two nitrogen donors of the co-ligands in the cis position The presence of uncoordinated bpds between the interpenetrated layers leads to the formation of a wafer-like structure for 2 In complex 3, however, manganese(II) ions bridged by 4,4′-bipy and coordinated by four water molecules give rise to a 1D polymeric chain The adjoining chains encapsulate terephthalate anions (tp) to give a 3D structure through H-bonding Low-temperature magnetic data indicate weak antiferromagnetic coupling in complexes 1 and 2 (© Wiley-VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2005)

Highly enhanced H2 gas sensing characteristics of Co:ZnO nanorods and its mechanism

Abstract: We report here excellent H 2 gas response property of Co-doped ZnO nanorods (Co:ZnO NRs). Co:ZnO NRs have been synthesized by hydrothermal method by varying the Co content from 0 to 10 mol%. It is found that Co:ZnO NRs with 8 mol% of Co exhibits the highest and faster H 2 gas response ability compared to the undoped ZnO resulting in a ∼5 fold enhancement in the gas response in the presence of air at 150 °C. While the gas response value (S (%) = [(I g -I a )/I a ] × 100, where I a is the current of the sensors in the presence of air only and I g is the current in the presence of certain H 2 concentration) to 3000 ppm H 2 for undoped ZnO NRs’sensor is 11%, an unprecedented high value of 53.7% is obtained for the Co:ZnO with 8 mol% of Co. Based on the electrical current and photoluminescence results, a mechanism for the enhanced H 2 response of Co:ZnO is proposed that involves donor-related oxygen vacancies (V O ) introduced by the Co dopants in the ZnO lattice.

Gel Sculpture: Moldable, Load-Bearing and Self-Healing Non-Polymeric Supramolecular Gel Derived from a Simple Organic Salt

Abstract: An easy access to a library of simple organic salts derived from tert-butoxycarbonyl (Boc)-protected L-amino acids and two secondary amines (dicyclohexyl- and dibenzyl amine) are synthesized following a supramolecular synthon rationale to generate a new series of low molecular weight gelators (LMWGs). Out of the 12 salts that we prepared, the nitrobenzene gel of dicyclohexylammonium Boc-glycinate (GLY.1) displayed remarkable load-bearing, moldable and self-healing properties. These remarkable properties displayed by GLY.1 and the inability to display such properties by its dibenzylammonium counterpart (GLY.2) were explained using microscopic and rheological data. Single crystal structures of eight salts displayed the presence of a 1D hydrogen-bonded network (HBN) that is believed to be important in gelation. Powder X-ray diffraction in combination with the single crystal X-ray structure of GLY.1 clearly established the presence of a 1D hydrogen-bonded network in the xerogel of the nitrobenzene gel of GLY.1. The fact that such remarkable properties arising from an easily accessible (salt formation) small molecule are due to supramolecular (non-covalent) interactions is quite intriguing and such easily synthesizable materials may be useful in stress-bearing and other applications.

Carbon Nanosheets by Morphology-Retained Carbonization of Two-Dimensional Assembled Anisotropic Carbon Nanorings

Abstract: Two-dimensional (2D) carbon nanomaterials possessing promising physical and chemical properties find applications in high-performance energy storage devices and catalysts. However, large-scale fabrication of 2D carbon nanostructures is based on a few specific carbon templates or precursors and poses a formidable challenge. Now a new bottom-up method for carbon nanosheet fabrication using a newly designed anisotropic carbon nanoring molecule, CPPhen, is presented. CPPhen was self-assembled at a dynamic air-water interface with a vortex motion to afford molecular nanosheets, which were then carbonized under inert gas flow. Their nanosheet morphologies were retained after carbonization, which has never been seen for low-molecular weight compounds. Furthermore, adding pyridine as a nitrogen dopant in the self-assembly step successfully afforded nitrogen-doped carbon nanosheets containing mainly pyridinic nitrogen species.