NOPR Collection:

Theoretical study of ¹¹B NMR chemical shifts of prototypical boranes: The case of closo-[B₁₂H₁₂]^2-, nest-B₁₁H₁₅, and arachno-B₁₀H₁₆

2018-02-20T07:02:43Z

Title: Theoretical study of ¹¹B NMR chemical shifts of prototypical boranes: The case of closo-[B₁₂H₁₂]^2-, nest-B₁₁H₁₅, and arachno-B₁₀H₁₆ Authors: Morales-Bayuelo, A; Lavín, J M Catalán; Ramírez-Tagle, R Abstract: The structural and electronic dependence of the ¹¹B chemical shifts for a series of borane structures, namely, closo-[B₁₂H₁₂]^2-, nest-[B₁₁H₁₅], and arachno-[B₁₀H₁₆] are investigated using density functional theory calculations. Three types of environments are identified for the borane systems, in increasing order of chemical shielding as: B-H < B-H-B < B-B-B. The obtained chemical shifts are in good agreement with the available experimental results and reflect the extent of heterogeneity of the electronic environments present in these chemical systems in terms of symmetry and the number of boron cores. In addition, results of molecular quantum similarity studies using similarity descriptors such as overlap and coulomb indices and Euclidean distances are also reported. Page(s): 143-149

Theoretical investigation into the cooperativity effect and thermodynamic property of β-nitroguanidine∙C₂F₄∙H₂O ternary complex

2018-02-20T06:55:27Z

Title: Theoretical investigation into the cooperativity effect and thermodynamic property of β-nitroguanidine∙C₂F₄∙H₂O ternary complex Authors: Li, Bin; Zhao, Guang-ming; Guo, Xiao-juan Abstract: The H-bonding cooperativity effects in β-NQ (nitroguanidine)∙∙∙C₂F₄∙∙∙H₂O ternary complex are investigated by the B3LYP and MP2(full) methods with the 6-311++G(2df,2p) basis set. The thermodynamic cooperativity effects are evaluated at 298.15 K. The result shows that C₂F₄ can be used as a wastewater treatment agent for β-NQ. The influence of the N–H∙∙∙O or O–H∙∙∙F H-bonding interaction on the N–H∙∙∙F interaction is more pronounced than that of the latter on the former. The weak cooperativity effect appears in the linear complex while the notable anti-cooperativity effect is seen in the cyclic system. The enthalpy change is the major factor driving the cooperativity. There is no obvious correlation between the cooperativity effects evaluated by interaction energies and those from thermodynamic data. The complexation energies (E_int.) correlate well with the local minima of surface electrostatic potentials (V_S_,min) or internal charge separations (Π). AIM (atom in molecule) analysis is used to reveal the nature of cooperativity effect. It can be inferred that the wastewater treatment for explosives can be viewed as a cooperativity process of coexisting intermolecular interactions, and also a thermodynamic cooperativity process. Page(s): 150-162

Binding interaction of a piperazinylquinoline derivative with β-cyclodextrin and Cd²⁺ ions

2018-02-20T06:44:58Z

Title: Binding interaction of a piperazinylquinoline derivative with β-cyclodextrin and Cd²⁺ ions Authors: Sumithra, M; Selvan, G Tamil; Suganthi, S; Selvakumar, P Mosae; Enoch, Israel VMV Abstract: Cd²⁺ ion sensing by 3-methyl-2-(piper-azin-l-yl)quinoline using fluorescence spectroscopy is reported. The host-guest complex formation of the compound with β-cyclodextrin is studied using UV-visible absorption, fluorescence, and 2-dimensional ROESY spectroscopic methods. The stoichiometry and the mode of binding of the compound with the host molecule are reported. The 1:1 Cd²⁺ complexation of the compound is effected on encapsulation by β-cyclodextrin. Page(s): 163-167

Ion-pair single-drop microextraction with ATR-FTIR determination of phosphate in water samples

2018-02-20T06:38:05Z

Title: Ion-pair single-drop microextraction with ATR-FTIR determination of phosphate in water samples Authors: Chandrawanshi, Swati; Verma, Santosh Kumar; Deb, Manas Kanti Abstract: A simple, rapid and green ion-pair single-drop microextraction procedure followed by attenuated total reflectance-Fourier transform infrared technique has been developed for the analysis of phosphate in water samples. This method is based on the extraction of the phosphate-cetyltrimethylammonium bromide ion-pair by the single-drop extraction procedure. The linear range for calibration plot of phosphate is 1-900 ng mL^-1, with good correlation coefficient (r² = 0.998). The limit of detection, limit of quantification, standard deviation and relative standard deviation of six replicate measurements are respectively 0.34 ng mL^-1, 1.12 ng mL^-1, 0.001 and 0.94-3.36%. The significant parameters such as selection of solvent, their volume, ion-pair reagent and their concentration, extraction time, stirring rate, sample pH, extraction temperature and effect of salt concentration are studied and optimized. The present method is successfully applied for the quantification of phosphate in water samples with minimal solvent consumption and sensitivity as compared with the conventional methods. Page(s): 168-174

NOPR Collection:

Theoretical study of 11B NMR chemical shifts of prototypical boranes: The case of closo-[B12H12]2-, nest-B11H15, and arachno-B10H16

Theoretical investigation into the cooperativity effect and thermodynamic property of β-nitroguanidine∙C2F4∙H2O ternary complex

Binding interaction of a piperazinylquinoline derivative with β-cyclodextrin and Cd2+ ions

Ion-pair single-drop microextraction with ATR-FTIR determination of phosphate in water samples

Theoretical study of ¹¹B NMR chemical shifts of prototypical boranes: The case of closo-[B₁₂H₁₂]^2-, nest-B₁₁H₁₅, and arachno-B₁₀H₁₆

Theoretical investigation into the cooperativity effect and thermodynamic property of β-nitroguanidine∙C₂F₄∙H₂O ternary complex

Binding interaction of a piperazinylquinoline derivative with β-cyclodextrin and Cd²⁺ ions