NOPR Collection:

Solvent-free facile synthesis of di-octyl phthalate over heterogeneous sulfated zirconia acid catalyst

2017-07-18T12:01:11Z

Title: Solvent-free facile synthesis of di-octyl phthalate over heterogeneous sulfated zirconia acid catalyst Authors: Parmar, Ajay M; Saravanan, K; Tyagi, Beena; Srinivasan, Kannan Abstract: The present study reports the synthesis of di-octylphthalate (DOP),widely used as a plasticizer, via solvent-free esterification of phthalic acid and n-octanol over sulfated zirconia (SZr) heterogeneous acid catalyst. A comparison with other heterogeneous acid catalysts such as K-10 acid activated clay, zeolites (β and Y), Amberlyst-15 resin shows the superior activity of SZr, exhibiting maximum conversion of n-octanol (88%) with 93% DOP selectivity at 160 °C in 6 h. The rate of the reaction for SZr catalyst is computed as 17.3 mmol h⁻¹ g⁻¹. The catalyst activity is stable upon recycling for up to five cycles. The weak acid sites of the catalyst are postulated as the responsible active centres involved in the reaction. The reaction has been successfully scaled up over twenty five times; and the product DOP (67 g, 99% by GC) isolated and characterized by FT-IR and ¹H NMR spectroscopy.It is noteworthy that the activity of SZr catalyst is comparable with that of H₂SO₄ and p-toluene sulphonic acid (p-TSA), which clearly suggetsits potential as an efficient alternative to conventional commercial homogeneous acid catalysts for the synthesis of DOP. Page(s): 747-755

Effect of charge and spin multiplicity on hyperpolarizabilities of donor-acceptor substituted polyenes

2017-07-18T12:03:48Z

Title: Effect of charge and spin multiplicity on hyperpolarizabilities of donor-acceptor substituted polyenes Authors: Ghosh, Subhadip; Roy, Ria Sinha; Banerjee, Paramita; Mondal, Avijit; Hatua, K; Nandi, Prasanta K Abstract: Theoretical studies of the ground state structure and nonlinear optical (NLO) properties of a number of donor-acceptor substituted singlet and triplet (neutral) and doublet (mono-positive and mono-negative) polyenes have been carried out. The variation of NLO property of the investigated molecules has been explained by using previously derived relationships between the different order polarizabilities and ground state dipole moment obtained in the framework of the standard sum-over-state expressions of Orr-Ward-Bishop and the generalized Thomas-Kuhn sum rule. The effect of charge and spin multiplicity on the molecular hyperpolarizabilities have been discussed in terms of relative changes of polarizability and ground state dipole moment. Among the investigated polyenes, the isotropic polarizability and the second-hyperpolarizability are predicted to be larger for the doublet anions in which the NH₂ group is pyramidal. The position of nitrogen atom in the -conjugative path strongly modulates the magnitudes of both the first- and second-hyperpolarizabilities of the investigated polyenes. Page(s): 756-766

Layer-by-layer synthesis of nano Prussian blue electrochromic thin film modified electrodes

2017-07-17T09:48:10Z

Title: Layer-by-layer synthesis of nano Prussian blue electrochromic thin film modified electrodes Authors: Shaal, Shaza Al; Karabet, Francois; Kellawi, Hasan Abstract: A novel simple non-electrical fully controlled method has been developed for synthesis of modified electrodes by Prussian blue thin film on indium tin oxide substrates. The method comprises a tiny spot of silver as a sacrificed anode applied on one corner of the substrate by using layer-by-layer method for deposition nano Prussian blue thin film layers of electrodes (LBL/Ag), from a solution of equal concentrations of ferric chloride and potassium ferricyanide. The morphology of Prussian blue nanoparticles has been investigated by scanning electron microscopy and atomic force microscopy. The Prussian blue thin film thickness has been calculated. The Prussian blue film exhibits linear increase in the UV-vis light absorbance with the number of deposited layers, indicating that well organized lamellar systems are involved, which is consistent with the results based on the cyclic voltammetry measurements. These results show excellent electrochemical and reversible stable thin films, favorable for various applications such as electrochromic devices. Page(s): 767-773

Geminally biotinylated cyclotriphosphazenes as molecular binding probe

2017-07-17T09:42:26Z

Title: Geminally biotinylated cyclotriphosphazenes as molecular binding probe Authors: Ma, Xuebin; Xu, Tingting; Chen, Wei; Wang, Rui; Xu, Zheng; Chi, Bo; Ye, Zhiwen Abstract: Biotinylated cyclotriphosphazenes polymer (g-BTP) with geminal octopus-like molecular shape has been prepared and characterized by ³¹P-NMR, ¹H-NMR and Matrix-assisted laser desorption ionization-time of flight-mass spectrometry (Maldi-Tof-Ms). Analysis of the size distribution of the complexes showed that the aggregated g-BTP/avidin complexes were rather polydispersed and uniform as compared to complexes formed by random coil biotinylated linear polymer (BLP) and avidin. Binding kinetics studies show that both of g-BTP and BLP can bind avidin very quickly. The binding ability as evaluated by Scatchard plot indicates the binding ability of g-BTP to be about 5.5 times that of BLP. Page(s): 774-779