Spectrophotometric study of the supramolecular complexes of [60]- and [70]Fullerenes with biscalix[6]arene and crown[4]calix[6]arene

[60]- and [70]Fullerenes have been shown to form 1:1 supramolecular complexes with bis[2-(5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41-pentahydroxycalix[6]arenyl-oxy ethyl ether) (1) and 5,11,17,23,29,35-hexa-tert-butyl-37,38,40,41-tetra hydroxyl-39,42-(crown-4)calix[6]arene (2) in CHCl3 medium by electronic absorption spectroscopy. Formation constants (K) of the complexes of [60]- and [70]fullerenes with 1 and 2 have been determined at room temperature from which free energy of formation values of the complexes have been estimated. The very high formation constant value of [60]fullerene/1 complex (5900 dm3 mol-1) in indicative of formation of inclusion complex. Moreover, PM3 calculations reveal that intermolecular interaction between [60]fullerene and 1 proceeds through quite deep energy molecular orbital.     

An efficient and modified biginelli one‐pot synthesis of new isoxazole substitted 3,4‐dihydropyrimidin‐2(1H)‐ones and thiones catalyzed by VCl3

An efficient and modified Biginelli one‐pot synthesis of new‐isoxazole substituted 3,4‐dihydropyrimidin‐2(1H)‐ones and thiones from aromatic aldehydes, ketoamide and urea/thiourea in acetonitrile using VCl₃ as the catalyst is described.     

QM/MM study of the interaction between zigzag SnC nanotube and small toxic gas molecules

Adsorptions of small toxic molecules such as CO, N₂, HCN, SO₂, H₂CO, and NH₃ on a single‐walled (6,0) SnC nanotube (SnCNT) are investigated using Quantum Mechanics/Molecular Mechanics (QM/MM) methodology. The calculations are carried out at the B3LYP/6‐311++G(d,p)//LANL2DZ:UFF level of theory. The high layer of the model consists of a pyrene‐type ring on the nanotube surface as the adsorption site, where one gas molecule is allowed to interact. Conversely, for the adsorption of the two molecules, a larger site like a coronene ring is used for the high layer. Adsorption energy, Gibbs free energy change, Mulliken charge transfer, and total electron‐density maps are computed in each case. The adsorption strength of the gas molecule on the SnCNT surface is also analyzed from the density of states projected to different atoms (PDOS) of the nanotube–adsorbate complexes. The adsorptions of CO and N₂ on the (6,0) SnCNT surface require to cross potential barriers, and the corresponding transition structures are identified by ONIOM‐IRC calculations. For the remaining four molecules, the processes of adsorption are predicted to be barrier‐less. The calculations for the adsorption of H₂CO on (5,0) and (7,0) SnCNT surfaces are extended to study the effect of the size of the nanotube. Results for the adsorption of a single molecule on (6,0) SnCNT using B3LYP functional are compared with those obtained from a dispersion corrected functional such as M06‐2X. © 2015 Wiley Periodicals, Inc.     

Simple Chemical Route Synthesis of Fe2O3 Nanoparticles and its Application for Adsorptive Removal of Congo Red from Aqueous Media: Artificial Neural Network Modeling

Nanocrystalline Fe₂O₃ powder was synthesized by a simple chemical route involving FeCl₃ and NaOH. The Fe₂O₃ powder thus prepared was characterized using x-ray diffraction study, scanning electron microscopy, and Fourier transform infrared spectroscopy. The adsorption properties of crystalline Fe₂O₃ powder have been investigated with an aim to explore a possible low cost and efficient way to remove Congo red (CR) from waste water. Fe₂O₃ powder was found as an excellent adsorbent for CR from aqueous medium. Adsorption capacity as much as 203.66 mg g^?1 is reported at room temperature. Effect of different experimental parameters such as reaction pH, initial CR dye concentration, adsorbent dose, and reaction temperature were studied on adsorption capacity of Fe₂O₃ powder and modeled by artificial neural network (ANN). Optimal ANN structure (4–5–1) shows minimum mean squared error (MSE) of 0.00235 and determination coefficient (R²) of 0.991 with Levenberg–Marquardt algorithm. Isotherm analysis of experimental data exhibited better fit to the Langmuir isotherm. The adsorption process was found to follow second-order kinetics as depicted by the analysis of experimental results. Thermodynamic study shows that the adsorption process is endothermic, spontaneous, and thermodynamically favorable in the temperature range of 27°C to 60°C.     

Structural features of some small carbonyls in the 1,3nπ states: An mcscf study

Structural features of a series of tetraatomic carbonyls in the ^1,3nπ* states are studied by using a recently proposed MCSCF algorithm at the INDO/2 level. The computed geometrical parameters and the inversion barrier heights agree quite well with the available experimental or ab initio theoretical data. The calculated transition energies turn out to be somewhat lower than the experimental counterparts. The specific MCSCF algorithm used is found to have excellent convergence properties.     

Synthesis of 3‐aminomethylidenechroman‐2‐carboxamides by a Sequential One‐pot Three Component Reaction and by Post‐Passerini Condensation Modification

3‐Arylaminomethylidenechroman‐2‐carboxamide has been synthesized by a one‐pot three component reaction among 3‐formylchromone, aromatic amine, and cyclohexyl isocyanide. 3‐(N‐alkylsubstitued/unsubstituted)aminomethylidenechroman‐2‐carboxamides were synthesized by heating Passerini products derived from chromone‐3‐carbaldehyde with different aliphatic primary amines. The products obtained from the reactions of aliphatic primary amines readily form chromeno[2,3‐c]pyrrole when heated in acetic acid. Bischromanones have also been synthesized using this methodology.     

Correlation analysis of reactivity in the addition of substituted benzylamines to ethyl α-cyanocinnamate

The kinetics of addition of a number of ortho-, meta-, and para-substituted benzylamines to ethyl α-cyanocinnamate (ECC) in acetonitrile have been studied. The reaction is first-order with respect to the amine and ECC. The rates of reaction of meta- and para-substituted benzylamines showed excellent correlations with Taft's σ₁ and σ_R⁰, and with σ₁ and σ_R^BA values, respectively. The reaction of the ortho-compounds showed a very good correlation with Charton's triparametric equation. The reaction is subject to steric hindrance by the ortho-substituents. A mechanism involving formation of a zwitterionic intermediate in a slow step followed by a fast proton transfer has been proposed. © 1996 John Wiley & Sons, Inc.     

Relative reactivities of glycerophosphates towards permanganate in perchloric acid medium

Summary The reactivities of - and -glycerophosphates towards MnO ₄ ^– in HClO₄ medium have been examined. The reactions between glycerophosphates and MnO ₄ ^– are first order with respect to [glycerophosphate], [MnO ₄ ^– ] and [H⁺]. There is no evidence for cleavage of the C–O–P bond rather than the terminal –CH₂OH group being oxidized to the respective phosphoglyceraldehyde.     

A quantum stochastic Lie-Trotter product formula

A Trotter product formula is established for unitary quantum stochastic processes governed by quantum stochastic differential equations with constant bounded coefficients.