Impact of immobilized polysaccharide chiral stationary phases on enantiomeric separations

Immobilized polysaccharide-based chiral stationary phases (CSPs) are gaining importance in the resolution of racemic compounds due to their stable nature on working with normal solvents and those prohibited for use with coated phases (tetrahydrofuran, chloroform, dichloromethane, acetone, 1,4-dioxane, ethyl acetate, and certain other ethers). This review discusses the use of immobilized polysaccharide CSPs in the chiral resolution of various racemates by liquid chromatography. The discussion includes immobilization methodologies, enantioselectivities, efficiencies, and a comparison of chiral recognition capabilities of coated vs. immobilized CSPs. Some applications of immobilized CSPs to the chiral resolution of racemic compounds are also presented.     

Homogeneous polynomials with isomorphic milnor algebras

We recall first Mather’s Lemma providing effective necessary and sufficient conditions for a connected submanifold to be contained in an orbit. We show that two homogeneous polynomials having isomorphic Milnor algebras are right-equivalent.     

Study of optoelectronic energy bands and molecular energy levels of tris (8-hydroxyquinolinate) gallium and aluminum organometallic materials from their spectroscopic and electrochemical analysis

For the purpose of investigating electro-molecular absorption bands, energy gaps, E_g and molecular energy levels (ionization potential, IP and electron affinity, EA) of tris (8-hydroxyquinolinate) gallium and aluminum, spectral analysis in conjunction with electrochemical measurements was carried out. UV-Vis-NIR and FTIR spectroscopic measurements were used to assign the electronic and molecular absorption bands in both of the materials. The XRD and scanning electronic microscopy (SEM) technique showed the amorphous nature. From the recorded data of cyclic voltammetry (CV) and materials absorption coefficient, HOMO, LUMO energy levels and energy gaps for Gaq3 and Alq3 were calculated. A bit smaller value of energy gap for Gaq3 (2.80 eV) compared to that of Alq3 (2.86 eV) has been ascribed to the differences in electronic configuration and coordinated bond lengths related to the central metal atom with respect to the quinolinate ligands. A higher value of HOMO energy level for the Alq3 (IP = 6.3 eV) revealed the need of higher potentials to oxidize its molecules comparing to that of Gaq3 (IP = 5.8 eV). It was observed that cationic metals have a direct effect on the physical and chemical behaviors of such organometallic materials that can be exploited to be used in tuning their properties to match the desired application in OSC and/or OLED technologies.     

Optical properties of a-Se90In10−x Snx chalcogenide thin films before and after gamma irradiation

Amorphous Se₉₀In_10?xSn_x (x=2, 4, 6, and 8) thin films of thickness 1000 Å were prepared on glass substrates by the thermal evaporation technique. Optical parameters of the films were investigated, in the wavelength range 400–700 nm, before and after irradiation by 4, 8, and 12 kGy doses of γ-ray. The optical absorption coefficient α for as-deposited and gamma irradiated films was calculated from the reflectance R and transmittance T measurements, which were recorded at room temperature. From the knowledge of α, at different wavelengths, the optical band gap E_g was calculated for all compositions of Se–In–Sn thin films before and after gamma irradiation. Results indicate that allowed indirect optical transition is predominated in as-deposited and irradiated films. Besides, it is found that the band gap decreases with increasing Sn concentration and this is attributed to the corresponding decrease in the average single bond energy of the films. The band gap, after irradiation at different doses of γ-ray, was found to decrease for all compositions of the studied films. This post-irradiation decrease in the band gap was interpreted in terms of a bond distribution model.     

Preparation, structure and spasmolytic activities of some derivatives of harmine series of alkaloids

Keeping in view the interesting chemistry and pharmacological importance of harmine series of bases -- the beta-carboline alkaloids, a number of new derivatives of tetrahydroharmine and harmalol have been prepared and characterized through spectral studies. Some of these derivatives showed spasmolytic activity. It was observed that all the N-acyl tetrahydroharmine derivatives are stable, not labile and no ring opening occurs in these compounds, as reported recently.     

A note on: Quasi-linear quotients and shellability of pure simplicial complexes

The purpose of this note is to point out a careless error in the algebraic criterion of shellability of a pure simplicial complex Δ given in [1 Anwar, I., Raza, Z. (2015). Quasi-linear quotients and shellability of pure simplicial complexes. Commun. Algebra 43:4698–4704.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]].     

On the metric dimension of barycentric subdivision of Cayley graphs

Acta Mathematicae Applicatae Sinica, English Series - In a connected graph G, the distance d(u, v) denotes the distance between two vertices u and v of G. Let W = {w 1, w 2, ···, w...     

Liquid chromatographic-tandem mass spectrometric assay for the simultaneous quantification of Camptosar and its metabolite SN-38 in mouse plasma and tissues

A simple, rapid and sensitive LC-MS/MS bioanalytical method has been developed to simultaneously quantify Camptosar (CPT-11) and its active metabolite, SN-38, in mouse plasma and tissues. A single step protein precipitation with acetonitrile in 96-well plates was used for sample preparation. Camptothecin (CPT) was used as the internal standard. Fast separation of SN-38, CPT-11 and CPT was carried out isocratically on a C18, 2 mm x 50 mm, 5 microm HPLC column with a mobile phase containing acetonitrile and 20 mM ammonium acetate (pH 3.5) and a 2.5 min chromatographic run time. The API 4000 MS/MS system was operated in positive ionization multiple reaction monitoring mode, and the transitions for SN-38, CPT-11 and CPT were 393.4 --> 349.3, 587.6 --> 167.2 and 349.3 --> 305.3, respectively. The SN-38 and CPT-11 concentrations in samples were calculated from a standard curve of peak area ratios of the analyte to that of the internal standard using a 1/chi2 weighted linear regression. The quantitation limit of 0.5 ng/mL was achieved by using a low sample volume (100 microL) of plasma or tissue homogenates. The assay was linear over the concentration range of 0.5-500 ng/mL with acceptable precision and accuracy. The method was used for the quantification of CPT-11 and SN-38 in plasma and tissues to support a preclinical pharmacokinetics and tissue distribution study of CPT-11 in mice.     

A Tetranuclear Propane-1,3-Dithiolate Complex, [Fe2(CO)5{Ph2P(CH2)3}{(µ-SCH2)2CH2}]2, with a Bridging 1,6-Bis(diphenylphosphino)hexane Ligand

The 2:1 molar reaction of [Fe₂(CO)₆{(µ-SCH₂)₂CH₂}] (1) and a bidentate diphosphine ligand, 1,6-bis(diphenylphosphino)hexane (dpph), in the presence of Me₃NO resulted in the isolation of [Fe₂(CO)₅{Ph₂P(CH₂)₃}{(µ-SCH₂)₂CH₂}]₂ (2) as red crystals in 71?% yield. The dpph ligand in compound 2, coordinates two Fe₂S₂ subunits as bridging mode and hence makes a linkage between two [Fe₂(CO)₅{(µ-SCH₂)₂CH₂}] fragments. Each Fe₂S₂ butterfly of the complex consists of two fused Fe(S-C-C-C-S) six-membered rings, one of which attains a chair conformation, and the other is necessarily in a boat conformation. Compound 2 has unequivocally been characterized by elemental analysis, IR, ¹H NMR and ³¹P NMR spectroscopy together with single crystal X-ray diffraction studies. Crystals of 2 are triclinic, space group P-1, a = 9.918(4) Å, b = 10.347(3) Å, c = 14.581(5) Å, α?=?72.239(12)º, β?=?80.342(12)º, γ?=?68.550(14)º and Z = 1.

Graphic Abstract

A novel tetranuclear propane-1,3-dithiolate complex, [Fe₂(CO)₅{Ph₂P(CH₂)₃}{(μ-SCH₂)₂CH₂}]₂ (2), bearing a bridging bis(diphenylphosphino)hexane (dpph) ligand, was synthesized from the Me₃NO aided room temperature displacement of carbonyls from [Fe₂(CO)₆{(μ-SCH₂)₂CH₂}] (1), and structurally characterized.

     

Pharmacological Justification for the Medicinal Use of Plumeria rubra Linn. in Cardiovascular Disorders

Plumeria rubra (L.) is a traditional folkloric medicinal herb used to treat cardiovascular disorders. The present investigation was methodically planned to investigate the pharmacological foundations for the therapeutic effectiveness of P. rubra in cardiovascular illnesses and its underlying mechanisms. Ex vivo vaso-relaxant effects of crude leaf extract of P. rubra were observed in rabbit aorta ring preparations. Hypotensive effects were measured using pressure and force transducers connected to the Power Lab data acquisition system. Furthermore, P. rubra displayed cardioprotective properties in rabbits when they were exposed to adrenaline-induced myocardial infarction. In comparison to the intoxicated group, the myocardial infarction model showed decreased troponin levels, CK-MB, LDH, ALT, ALP, AST, and CRP, as well as necrosis, apoptosis, oedema, and inflammatory cell enrollment. P. rubra has revealed good antioxidant properties and prolonged the noradrenaline intoxicated platelet adhesion. Its anticoagulant, vasorelaxant, and cardioprotective effects in both in vivo and ex vivo investigations are enabled by blocking L-type calcium channels, lowering adrenaline, induced oxidative stress, and tissue tear, justifying its therapeutic utility in cardiovascular disorders.