Characterization of a Novel Curcumin based Schiff base Ligand, Synthesized by Microwave Method

A new Schiff base ligand derived from curcumin and ethylenediamine has been synthesized by the microwave irradiation method. The synthesized ligand was characterized by using FT-IR, UV-VIS, Molar conductance, NMR, PL and DLS studies. The results confirmed that the successful formation of Curcumin Based Schiff Base ligand. The ligand synthesized was stable at room temperature, completely soluble in hot methanol/DMF, partially soluble in ethanol/DMSO/acetone and insoluble in water. The spectra studies of FTIR and UV-visible confirmed the formation of the azomethine group in the ligand. NMR spectrum confirmed the presence of aromatic proton, hydroxyl proton, amine proton etc in the ligand. The luminescent property of the ligand was confirmed by the photoluminescence spectroscopic method. The low molar conductance value showed the non-electrolytic nature of the ligand. The dynamic light scattering studies showed that the ligand synthesized was in nanometer scale. The structure of the ligand was also proposed based on the analysis reports.

Dissolution of bamboo hemicellulose in 1-butyl-3-methylimidazolium halide-based ionic liquids

Understanding the dissolution of hemicellulose in ionic liquids (ILs) is important in order to explore efficient utilization of ILs for fractionating lignocellulose and extracting hemicellulose. In this study, three ILs, namely 1-butyl-3-methylimidazolium chloride (BmimCl), 1-butyl-3-methylimidazol-ium bromide (BmimBr), and 1-butyl-3-methylimidazolium iodide (BmimI), were used as solvents to dissolve bamboo hemicellulose over the temperature range of 80 °C to 150 °C. Representative hemicellulose with a solubility higher than 9.0 g/100 g IL was regenerated and characterized. The interaction between the hemicellulose and ILs was evaluated using carbon-13 nuclear magnetic resonance. The results showed that the solubility of hemicellulose in the ILs was in the following order: BmimCl > BmimBr > BmimI. Though moderate degradation of the hemicellulose possibly occurred during dissolution, the main chain of the hemicellulose was almost unchanged. The enhanced solubility of the hemicellulose was because of the formation of hydrogen bonds between the hydroxyl proton of the hemicellulose and anion of the ILs.

Structure, aromaticity, and bonding in subporphyrins: theoretical study of [14]tribenzosubporphine(1.1.1)hydroxyboron(III) and [14]subporphine(1.1.1)hydroxyboron(III) complexes

A theoretical analysis of the structure, aromaticity, magnetic properties and bonding in TBSPBOH and SPBOH complexes was performed. Geometry optimizations were carried out in the gas-phase at the B3LYP/6-31G(d) theory level. 1 H and 13 C NMR spectra of these complexes were evaluated at the B3LYP/6-311+G(2d,p)-PCM theory level in CHCl 3 solution. The vector field induced by an external magnetic field was computed at the CHF/6-31G(d) theory level using the CTOCD-DZ formulation. In these cone-shaped molecules, the 14-π electron current induced in them by an external magnetic field does not follow a [14]-annulene path but the inner edge of the macrocycle. Therefore, the 14-π electron aromatic core corresponding to this induced current is constituted by the three meso C atoms, the three N atoms, and the six C atoms directly bonded to them. The involvement of the N atoms in the 14-π aromatic core implies that one of the B - N bonds is a weaker B←N dative bond whose presence is reflected in the geometry of these complexes, which display larger average B - N bond lengths than in tripyrrolylborane. Thus, according to our analysis, structure, aromaticity and bonding in these systems are closely related. The anisotropic effect is somewhat larger in SPBOH than in TBSPBOH, and the larger curvature of the former makes larger relative shielding constants possible, not only for the hydroxyl proton but also for the outer atoms.

The T, p-Dependence of the Chemical Shift of the Hydroxyl Protons in Deeply Supercooled Methanol and Water

The hydroxyl proton chemical shifts δ (H-O) of supercooled methanol (Tmin= 149 K) and water have been determined (Tmin= 183 K), and the pressure dependence of these shifts was measured up to 200 MPa. In both compounds the downfield shift of δ (H-O) continues down to the lowest temperatures reached. This result disagrees with the two state models for the hydrogen bond formation in both liquids. The isotherms δ(H2O) show for T< 273 K an upfield shift that becomes more pronounced with decreasing temperature. For δ ( H-O-CH3), increasing p causes at all temperatures a downshift

The Concentration and Temperature Dependence of the Deuterium Quadrupole Coupling Parameter and Rotational Correlation Time of Ethanol-Carbon Tetrachloride Binary Mixtures

Concentration and temperature dependent measurements of the hydroxyl proton chemical shift and deuterium longitudinal relaxation time of binary mixtures of ethanol and carbon tetrachloride were made over a 60 degree temperature range. Concentrations ranged from 1.02 mole percent to neat ethanol.