Oxomolybdenum(VI) and (IV) complexes of pyrazole derived ONO donor ligands – synthesis,crystal structure studies and spectroelectrochemical correlation

Four cis-dioxomolybdenum complexes of general formula [MoO₂(Lⁿ)EtOH] (n = 1–4) and one oxomolybdenum(IV) complex [MoO(L⁴)EtOH], with potentially tridentate Schiff bases derived from 5-methyl pyrazole-3-carbohydrazide and salicylaldehyde/substituted salicylaldehyde/o-hydroxy acetophenone have been prepared. The Mo(IV) complex is derived from the Mo(VI) dioxo complex by oxotransfer reaction with PPh₃. The complexes are characterized by elemental analysis, electronic spectra, IR, ¹H NMR, and by cyclic voltammetry. All the Mo(VI) species are crystallographically characterized. The complexes have a distorted octahedral structure in which the ligand behaves as a binegative donor one, leaving the pyrazole –N uncoordinated towards the metal center. It is also revealed from the crystal structure that the Mo(VI) center enjoys an NO₅ donor environment.     

Dual Solvatochromism of Neutral Red

Abstract— The effect of solvent polarity on the electronic absorption and fluorescence properties of neutral red (NR), a phenazine-based dye of biological importance has been investigated in several neat and mixed solvents. An unusual dual solvatochromic behavior has been observed that reveals the existence of two closely spaced electronic excited states in NR. In low-polarity solvents the fluorescence of the NR is mainly emitted from the localized excited state, whereas in high-polarity solvents the emission from the charge transfer state dominates. The dipole moments of the localized and charge transfer states of NR have been estimated from the solvatochromic shifts. The dipole moment of the localized excited state (4.8 D) is only slightly higher than that of the ground state (2.0 D), while that of the charge transfer state is drastically higher (17.5 D). Fluorescence quantum yields and the life-times of NR have been determined in different solvents and correlated with the solvatochromic shifts.     

Experimental and theoretical study of the reaction between bicyclo[2.2.1]hept-5-en-endo-2-ylmethylamine and 2-[(2-allylphenoxy)methyl]oxirane

In reactions of bicyclo[2.2.1]hept-5-en-endo-2-ylmethylamine with 2-[(2-allylphenoxy)methyl]oxirane alongside the product of amine monoalkylation a compound was obtained and isolated by chromatography on silica gel resulting from the reaction of the monoalkylated substance with the initial epoxide. The structure of new aminoalcohols and the regiochemistry of the oxirane opening were examined using IR, 1H NMR, and mass spectra. The features of the reaction mechanism were considered applying quantum-chemical calculations in the level of theory PCM/B3LYP/6-3aG(d).     

Polyhydroxamic Acid Sorbents for Uranium Recovery

Crosslinked polyacrylamides were synthesized by solution polymerization using benzoyl peroxide as the radical initiator. The water–insoluble polymer obtained was functionalized by reacting with hydroxylamine to convert the amide group into hydroxamic acid group. The resultant functionalized polymer was characterized in terms of moisture uptake, elemental composition, IR spectra, thermal stability, exchange capacity and heavy metal sorption. The sorbent, obtained in particulate form, was investigated for its sorption properties with respect to uranium from uranyl nitrate solutions under unstirred batch conditions. This paper will concentrate on preparation, characterization and performance evaluation with respect to uranium sorption as a function of concentration, time, solution pH and temperature. The potential of this sorbent for uranium and other heavy metal ion recovery from sea water is ascertained.     

Interaction of 3H+ (as HTO) and 36Cl− (as Na36Cl) with crushed granite and corresponding fracture infill material investigated in column experiments

The transport of ³H⁺ (as HTO) and ³⁶Cl^? (as Na³⁶Cl) was investigated in the dynamic system, i.e., in the columns filled with crushed pure granite and fracture infill of various grain sizes. The aim of column experiments was to determine important transport parameter, such as the retardation, respectively distribution coefficients, Peclet numbers and hydrodynamic dispersion coefficients. Furthermore, the research was focused to quantification of the effect of grain size on migration of studied radionuclides. The experimental breakthrough curves were fitted by a model based on the erfc-function, assuming a linear reversible equilibrium sorption/desorption isotherm, and the above mentioned transport parameters were determined. The results showed that influence of grain size on sorption of ³H⁺ and ³⁶Cl^? was negligible. Retardation and distribution coefficients of both tracers converged to one and zero, respectively, in case of all fractions of crushed granite and infill material. Generally, the presumed ion exclusion of ³⁶Cl in anionic form was proved under given conditions, only very weak one seems to exist in a case of infill material. In principal, both radionuclides behaved as non-sorbing, conservative tracers. On the other hand, the influence of grain size on Peclet numbers value and on dispersion coefficient was observed for both crystalline materials, namely in agreement with theoretical suppositions that the values of Peclet numbers decrease with increasing grain size and values of dispersion coefficient increase.     

Chemical Composition of Essential Oil from Pilea microphylla and its Antimicrobial Activity

Chemistry of Natural Compounds -     

Plasma Based Synthesis of Nanomaterials for Development of Plasmon Enhanced Infrared Responsive Optoelectronic Device

Plasma Chemistry and Plasma Processing - We report plasma based fabrication of an optoelectronic device with plasmon enhanced infrared sensitivity realized by integrating plasmonic gold...