Spectrophotometric Study of the Interaction of β‐Cyclodextrin with Hydroxamic acids

Cyclodextrins have attracted considerable interest because of their ability to form stable inclusion complexes with a wide variety of inorganic and organic guest molecules. In the present communication, binding constant of β‐cyclodextrin and a series of substituted benzohydroxamic acids (X‐C₆H₄CON(OH)H), X=H, 4‐NO₂, 4‐Me 4‐OMe, and 2‐OH and N‐phenylbenzohydroxamic acid (C₆H₅CON(OH)C₆H₅) were determined at 27°C spectrophotometrically. In all the cases the formation of 1:1 host‐guest complex was established. The addition of β‐CD results in an increase in the absorbance intensity but does not cause a shift in λ_max. The values of binding constants are in good agreement with in those determined from kinetic and pH metric techniques.     

Predicting DNA–intercalator binding: the development of an arene–arene stacking parameter from SAPT analysis of benzene‐substituted benzene complexes

A series of substituted naphthalimides were synthesized and intercalated into the DNA sequence d(GCGCGCGC)₂, and an experimental ΔT_m value was obtained. Two‐parameter QSAR analyses were performed to generate a theoretical ΔT_m value. Although by no means exhaustive in terms of parameter selection, the correlations did not yield statistics that indicated the models met the threshold for significance at the 95% confidence level. Rather than continue with an exhaustive search of all possible QSAR parameters, a one‐parameter QSAR analysis was performed utilizing a novel arene–arene stacking parameter, designated Π^π, developed from Symmetry‐Adapted Perturbation Theory (SAPT) energy decomposition studies of calculated benzene‐substituted benzene dimer binding energies. The QSAR analysis using the Π^π stacking parameter yielded statistics suggesting the model was significant at the 95% confidence level. The approach of developing a novel QSAR parameter via SAPT calculations, rather than exhaustively searching all traditional QSAR parameters, is presented both as a new approach for QSAR studies and as a unique application of SAPT. Copyright © 2013 John Wiley & Sons, Ltd.     

Solubility of pentane, 2-methylbutane,and cyclopentane in liquid nitrogen at 77.4 K

The solubilities of pentane, 2-methylbutane (isopentane) and cyclopentane were measured in liquid nitrogen at 77.4 K by the filtration method. The solubilities of the C₅ hydrocarbons in liquid nitrogen at 77.4 K vary from 1.8×10^–8 mole fraction for cyclopentane, to 3.0×10^–8 mole fraction for pentane and 3.2×10^–7 mole fraction for 2-metylbutane. Correlations between the solubilities of alkanes, alkenes and cyclic hydrocarbons in liquid nitrogen, and some properties of solutes [normal boiling point T _b , enthalpy of vaporization at normal boiling point H _b and the mean of the enthalpy of vaporization and the enthalpy of melting [(H _b +H _m )/2] are presented.     

Formation of α‐SF5‐Enolate Enables Preparation of 3‐SF5‐Quinolin‐2‐ones, 3‐SF5‐Quinolines,and 3‐SF5‐Pyridin‐2‐ones: Evaluation of their Physicochemical Properties

This study describes, for the first time, the generation of a SF₅‐substituted ester enolate from benzyl SF₅‐acetate under soft enolization conditions, which in turn participates in aldol addition reactions in high yield. The reaction was applied in the synthesis of 3‐SF₅‐quinolin‐2‐ones, 3‐SF₅‐quinolines, and 3‐SF₅‐pyridin‐2‐ones, none of which have previously been reported. To provide guidelines for their use in drug discovery, the physicochemical properties of these building blocks were determined and compared with those of their CF₃‐ and t‐Bu‐analogues.     

Effect of rope mat and random orientation on mechanical and thermal properties of banana ribbon-reinforced polyester composites and its application

The present work deals with the characterization of banana ribbon, a new natural fiber, and the effect of rope mat and random orientation on the mechanical and thermal properties of banana ribbon-reinforced polyester composites. Of all the fabricated composites, the banana ribbon rope mat composites showed improved mechanical and thermal properties compared to randomly oriented composites and other natural fiber composites. The surface morphologies of fractured mechanical testing samples were studied by scanning electron microscope to probe the fiber–matrix interaction. Furthermore, the mat composites are used to fabricate windshield of four wheelers and mudguard of two wheelers.