Journal of Molecular Structure 

About: Journal of Molecular Structure is an academic journal published by Elsevier BV. The journal publishes majorly in the area(s): Chemistry & Hydrogen bond. It has an ISSN identifier of 0022-2860. Over the lifetime, 33965 publications have been published receiving 460852 citations.

The Cologne Database for Molecular Spectroscopy, CDMS: a useful tool for astronomers and spectroscopists

Abstract: The general features of the internet browser-accessible Cologne Database for Molecular Spectroscopy (CDMS) and recent developments in the CDMS are described in the present article. The database consists of several parts; among them is a catalog of transition frequencies from the radio-frequency to the far-infrared region covering atomic and molecular species that (may) occur in the interstellar or circumstellar medium or in planetary atmospheres. As of December 2004, 280 species are present in this catalog. The transition frequencies were predicted from fits of experimental data to established Hamiltonian models. We present some examples to demonstrate how the combination of various input data or a compact representation of the Hamiltonian can be beneficial for the prediction of the line frequencies.

Interaction of drugs with bovine and human serum albumin

Abstract: The study on the interaction of antithyroid drugs: 2-mercapto-1-methylimidazole (Methimazole, MMI) and 6 n -propyl-2-thiouracil (PTU) with two kinds of serum albumin: bovine (BSA) and human (HSA) has been undertaken. Fluorescence emission spectra of serum albumin in the presence of MMI or PTU, recorded at the excitation wavelengths 280 and 295 nm, clearly show that the studied drugs act as quenchers. A decrease in fluorescence intensity at 340 or 350 nm, when excited at 280 or 295 nm, respectively, is attributed to changes in the environment of the protein fluorophores caused to the presence of the ligand. The 295 nm lights excites tryptophan residues, while the 280 nm lights excites both tryptophan and tyrosine residues. A comparison of quenching effects, when protein is excited at 295 and 280 nm, reveals that the tryptophanyl group interacts with the ligand. The differences in interactions of pyrimidine derivatives with HSA and BSA were observed using spectrofluorimetry technique. As the HSA structure contains only one tryptophanyl residue (Trp 214), while BSA has two ones (Trp 135 and Trp 214), the similar decrease of fluorescence points at the subdomain IIA, where Trp 214 was located, as a binding site of the studied drugs.

Synthesis and characterization by FTIR spectroscopy of silica aerogels prepared using several Si(OR)4 and R′′Si(OR′)3 precursors

Abstract: We report the synthesis and Fourier Transform Infrared spectroscopy characterization results dealing with the surface modification of silica aerogels obtained via a two-step sol–gel process where various silicon precursors and co-precursors were used. The hydrolysis and poly-condensation steps were followed by carbon dioxide supercritical drying (Tc = 31.1 °C; Pc = 73.7 bar). The silicon precursors contain four identical hydrolysable alkoxy groups (methoxy or ethoxy), while in the co-precursors, one of the alkoxy groups is substituted by a non-hydrolysable alkyl group (methyl, ethyl, n-propyl, iso-butyl, n-octyl, vinyl or phenyl). Identically, surface-functionalized silica aerogels were obtained from various silicon precursor/co-precursor combinations and their chemical structures were compared. The infrared spectroscopy revealed the existence of chemically comparable solid networks with some differences due to the nature of the silicon precursors.

Materials selection guidelines for membranes that remove co2 from gas mixtures

Abstract: Membrane technology has been investigated for removing CO 2 from mixtures with light gases such as CH 4 , N 2 and H 2 , and optimal membranes with high CO 2 permeability and high CO 2 /light gas selectivity are of great interest. This overview describes the material science approaches to achieve high CO 2 solubility and CO 2 /light gas solubility selectivity by introducing polar groups in polymers. CO 2 solubility and CO 2 /N 2 solubility selectivity in both liquid solvents and solid polymers containing a variety of polar groups are discussed. Optimum materials appear to have a solubility parameter of about 21.8 MPa 0.5 to achieve both high solubility and high solubility selectivity. However, the introduction of polar groups can decrease CO 2 diffusion coefficients and can make a material more size-selective, which is detrimental to, for example, CO 2 /H 2 separation properties. So far, ether oxygens in ethylene oxide (EO) units appear to provide a good balance of CO 2 separation and permeation properties. One drawback of using pure poly(ethylene oxide) (PEO) is its strong tendency to crystallize. This report reviews strategies for incorporating high concentrations of EO units into polymers while suppressing crystallization. A simple model, based on free volume theory, is used to correlate a wide range of CO 2 permeability coefficients in PEO containing materials, and the results are satisfactory, particularly given the simplicity of the model. Crosslinked poly(ethylene glycol) acrylate (XLPEO) containing branches with methoxy end groups exhibit the highest CO 2 permeability (i.e. 570 Barrers) and highest CO 2 /H 2 selectivity (i.e. 12) at 35 °C and infinite dilution among all PEO containing materials reported to date. Because such materials do not crystallize at typically accessible temperatures, CO 2 /H 2 selectivity can be further improved by decreasing temperature. For example, at an upstream pressure of 4.4 atm, CO 2 /H 2 pure gas selectivity reaches a value of 40 at −20 °C while maintaining a CO 2 permeability of 52 Barrers.