Publications

Energetics of contact pairs

No abstract is provided for this article.

Inorganic Graphene Analogs

In the last four to five years, there has been a great resurgence of research on two-dimensional inorganic materials, partly because of the impetus received from graphene research. Unlike graphene, which is a gap-less material, most inorganic layered materials are semiconductors or insulators. Some of them, as exemplified by MoS 2 , exhibit unexpected properties, not unlike graphene, with possible applications. Thus, layered metal chalcogenides are being explored intensely, and MoS 2 is emerging as a wonder material. In this article, we present the synthesis and properties of nanosheets composing single or few layers of these fascinating materials. Besides metal chalcogenides, boron nitride, borocarbonitrides (B x C y N z ), metal oxides, and metal-organic frameworks are also discussed.

CCDC 221802: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Fabrication of large-area PbSe films at the organic–aqueous interface and their near-infrared photoresponse

An organic–aqueous interfacial reaction at room temperature has been employed to synthesize large-area self-assembled films consisting of PbSe single crystallites. The use of the films for the low-cost fabrication of IR-photodetectors has been explored. (111)-oriented single crystallites of PbSe self-assemble to form robust large-area films. The near-infrared photoresponse of the film measured at room temperature showed large responsivity and gain owing to trap-associated mechanisms. Low-cost, mild reaction conditions and tunability of the nature of deposits make the present strategy useful for synthesizing large-area films of functional materials for possible opto-electronic applications.

Crystallographic study of the transition in Ti sub 2 O sub 3.

Titanium oxide lattice parameter changes in 390 to 470 K range studied by X ray crystallography, noting correlation of distension with resistivity changes

EXAFS studies of arsenic chalcogenide glasses

An EXAFS study at the AsK edge of the ternary glasses As2(S, Se)3 and As2(Se, Te)3 and the binary As2S3, As2Se3 and As2Te3 glasses has been carried out. Radial structure functions show that the environment of As in glasses of intermediate compositions is quite different from that in the binary glasses. In the As2(S, Se)3 system, this might arise from chemical disorder in the network while in the As2(Se, Te)3 system increased ionicity could be the cause of this behaviour. Glasses where the constituent atoms are of similar size seem to exhibit fewer peaks in the radial structure function.

Selectivity in the Interaction of Electron Donor and Acceptor Molecules with Graphene and Single-Walled Carbon Nanotubes

Interaction of electron donor and acceptor molecules with graphene samples prepared by different methods as well as with single-walled carbon nanotubes (SWNTs) has been investigated by isothermal titration calorimetry (ITC). The ITC interaction energies of the graphene samples and SWNTs with electron acceptor molecules are higher than those with electron donor molecules. Thus, tetracyanoethylene (TCNE) shows the highest interaction energy with both graphene and SWNTs. The interaction energy with acceptor molecules varies with the electron affinity as well as with the charge-transfer transition energy for different aromatics. Metallic SWNTs interact reversibly with electron acceptor molecules, resulting in the opening of a gap.

5-(DISUBSTITUTED)AMINO-1,2,3,4-THIATRIAZOLES

not available

Boron- and nitrogen-doped carbon nanotubes and graphene

Multi-walled, single-walled and double-walled carbon nanotubes as well as graphene can be doped with boron and nitrogen. B2H6 has been generally used as the boron source while NH3 or pyridine is employed as the nitrogen source. Doping carbon nanotubes and graphene with boron and nitrogen brings about significant changes in the electronic structure and properties. Such doping not only results in desirable properties but also allows manipulation of properties for specific purposes. Doping with boron- and nitrogen-causes marked changes in the Raman spectra of the carbon nanostructures. In this article, we present the synthesis, characterization and properties of boron- and nitrogen-doped carbon nanotubes and graphene.

ChemInform Abstract: Basic Building Units, Self‐Assembly and Crystallization in the Formation of Complex Inorganic Open Architectures

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

CCDC 600777: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Near infrared detectors based on HgSe and HgCdSe quantum dots generated at the liquid–liquid interface

HgSe and Hg0.5Cd0.5Se quantum dos (QDs) are synthesized at room temperature by a novel liquid–liquid interface method and their photodetection properties in the near-IR region are investigated. The photodetection properties of our Te-free systems are found to be comparable to those of the previously reported high performance QD vis-IR detectors including HgTe. The present synthesis indicates the cost-effectiveness of selenium based IR detectors owing to the abundance and lower toxicity of selenium compared to tellurium.

Anderson localization of IR light in 1D nanosystems

This contribution reports on the observation of a strong light localization of Anderson type in 1D systems consisting of ship-shaped carbon nanotubes. Such a localization of infrared (IR) light was observed using Fourier transform infrared spectroscopy under attenuated total reflection geometry within the spectral range of 2-20 µm. Such an IR light localization manifests itself in the form of a significant interference profile of the optical transmission over the full wavenumber range of 400-4000cm-1.

Metallic ReO₃ Nanoparticles.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

13C-n.m.r. studies of the conformational changes in proline oligomers brought about by lithium and calcium salts

A detailed 13C-n.m.r. investigation has been carried out on the conformational changes in proline oligomers brought about by interaction with lithium and calcium perchlorates. Interaction of lithium and calcium salts with Piv-(Pro)n-OMe, n = 2, 4 and 5 results in trans-cis isomerization. In the case of pentaproline, metal salts also give rise to other trans-isomers caused by the rotation about the C α C(O) bond (Ψ, cis). Calcium salts seem to stabilize cis'-isomers and produce effects somewhat different from those of lithium salts.

XPS and X-ray absorption edge studies of the surface and bulk valence states of cerium in CeCo₂

XPS and LIII X-ray absorption edge studies regarding the valence state of cerium have been carried out on the intermetallic compounds CeCo2, which becomes superconducting at low temperatures. It is observed from XPS that the surface shows both Ce3+ and Ce4+ valence states, while the X-ray absorption edge studies reveal only Ce4+ in the bulk. Thus valence fluctuation and superconductivity do not coexist in the bulk of this compound.

Infrared spectroscopic study of C₇ intramolecular hydrogen bonds in peptides

The ir‐spectra in the NH stretching region of Piv‐Pro‐NHMe and Boc‐Pro‐NHMe have been studied in carbon tetrachloride and chloroform solutions over a wide range of concentrations. Based on the concentration dependence of the NH stretching bands, it has been shown that the characteristic NH stretching band due to the C 7 intramolecular hydrogen bond is around 3335 cm −1 . Intermolecular hydrogen bonding also occurs to a small extent in these peptides, giving rise to a slight concentration dependence of the NH stretching bands. The band around 3335 cm −1 need not necessarily be due to C 7 hydrogen bonds alone as proposed by Tsuboi et al. or to intermolecular hydrogen bonding alone as proposed by Maxfield et al.; this conclusion is supported by studies on Boc‐Leu‐NHMe, which undergoes only intermolecular hydrogen bonding. We have shown that Z‐Aib‐Aib‐OMe and Z‐Aib‐Ala‐OMe form C 7 intramolecular hydrogen bonds in addition to C 5 intramolecular hydrogen bonds. The present studies also show that all the peptides studied exist in more than one conformation in solution.

Improved method for the synthesis of alkyl azides