Structure and Dynamics of the [Zn(NH3)(H2O)5]2+ Complex in Aqueous Solution Obtained by an ab initio QM/MM Molecular Dynamics Study.

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Synthesis and characterization of gallium oxide nanoparticles

This review is based on the literature describing several methods for the synthesis of gallium oxide nanoparticles. Several techniques have been used for the synthesis of gallium oxide Ga₂O₃ nanoparticles. Gallium oxide Ga₂O₃ nanoparticles have been synthesized from different precursors. Different synthetic methods and different precursors produce nanoparticles which vary in size and shape. Over a dozen of synthetic methods for preparation of gallium oxide Ga₂O₃ nanoparticles together with the characterization techniques used have been discussed.     

T-Analyst: a program for efficient analysis of protein conformational changes by torsion angles

T-Analyst is a user-friendly computer program for analyzing trajectories from molecular modeling. Instead of using Cartesian coordinates for protein conformational analysis, T-Analyst is based on internal bond-angle-torsion coordinates in which internal torsion angle movements, such as side-chain rotations, can be easily detected. The program computes entropy and automatically detects and corrects angle periodicity to produce accurate rotameric states of dihedrals. It also clusters multiple conformations and detects dihedral rotations that contribute hinge-like motions. Correlated motions between selected dihedrals can also be observed from the correlation map. T-Analyst focuses on showing changes in protein flexibility between different states and selecting representative protein conformations for molecular docking studies. The program is provided with instructions and full source code in Perl.     

Structure and dynamics of the [Zn(NH3)(H2O)5]2+ complex in aqueous solution obtained by an ab initio QM/MM molecular dynamics study

A model complex of the hexahydrated zinc(ii) cation with one water substituted by ammonia in aqueous solution has been studied by hybrid ab initio quantum mechanical/molecular mechanical (QM/MM) molecular dynamics (MD) at the double-zeta Hartree-Fock (HF) quantum mechanical level. The first solvation shell, consisting of 5 + 1 ligand(s) at mean distances of 2.2 and 2.1 A, respectively, from the Zn(ii) ion, was found to remain stable with respect to exchange processes within the simulation time. The labile second shell consists on average of approximately 19 water molecules. For structural elucidation of the pentaaquozinc(ii) amine complex in aqueous solution several data sets such as radial distribution functions (RDF), coordination number distributions (CND) and different angular distributions (ADF, tilt and theta angle) were employed. Dynamics were characterised by the ligands' mean residence time (MRT), ion-ligand stretching frequencies and the vibrational and librational motions of water ligands. The labile second shell's MRT value decreases upon introduction of one NH(3) ligand to 7.2 ps from the 10.5 ps observed for the hexaaquozinc(ii) complex.     

Synthesis,Structures, and Antibacterial Activities of Four Similar 1D Metal-organic Polymers with Different Metal Ions

Four similar 1D metal-organic polymers [Cd(impc)₂(H₂O)₂]_n ( 1 ), [Co(impc)₂(H₂O)₂]_n ( 2 ), [Mn(impc)₂(H₂O)₂]_n ( 3 ), and {[Cu(impc)₂] · [jy2H₂O}_n ( 4 ) based on an asymmetric 5-(1H-imidazole-l-yl)-3-pyridinecarboxylic acid (Himpc) were prepared hydrothermally and structurally characterized. According to the frontier molecular orbital (FMOs) calculations, the photoluminescence of 1 should be assigned as the n→π* transition. The antibacterial properties of 1 – 4 were studied. 1 exhibited good antibacterial activities towards B. subtilis and S. aureus with the smallest MIC value of 2 μg · mL^–1. Compared with Co^II, Mn^II and Cu^II ions, the polymer with Cd^II ion has the better antibacterial activity. Our work preliminarily reveals that the metal ions also have different influences on antibacterial activities of complexes.     

Radiocharacterization of the 99mTc�Crufloxacin complex and biological evaluation in Staphylococcus aureus infected rat model

^99mTc?Crufloxacin (^99mTc?CRUN) complex was prepared by reaction of different amounts of reduced sodium pertechnetate with different amount of Rufloxacin (RUN) antibiotic for the in vivo scintigraphic localization of the Staphylococcus aureus (S. aureus) infectious foci in Male Wister Rats (MWR) model. The ^99mTc?CRUN complex was radiochemically and biologically characterized in terms of radiochemical stability in saline, serum, in vitro binding with S. aureus and biodistribution in artificially infected with S. aureus MWR. The ^99mTc?CRUN complex showed stability more than 90% up to 240 min in normal saline with a maximum stability value of 98.10 ± 0.18% at 30 min after reconstitution. At 37 °C the complex showed in vitro permanence in serum up to 16 h with 13.90% side products during incubation. The ^99mTc?CRUN complex showed saturated in vitro binding with S. aureus at different intervals with a maximum uptake value of 71.50%. Infected to normal muscle, infected to inflamed and inflamed to normal muscles ratios were approximately 6.04, 4.31 and 1.40. Based on the stability of the complex in saline, serum, in vitro binding with S. aureus and biodistribution results, the ^99mTc?CRUN complex is recommended for in vivo scintigraphic localization of the S. aureus in vivo infectious foci in human.     

Excited state relaxation dynamics of model green fluorescent protein chromophore analogs: evidence for cis-trans isomerism

Two green fluorescent protein (GFP) chromophore analogs (4Z)-4-(N,N-dimethylaminobenzylidene)-1-methyl-2-phenyl-1,4-dihydro-5H-imidazolin-5-one (DMPI) and (4Z)-4-(N,N-diphenylaminobenzylidene)-1-methyl-2-phenyl-1,4-dihydro-5H-imidazolin-5-one (DPMPI) were investigated using femtosecond fluorescence up-conversion spectroscopy and quantum chemical calculations with the results being substantiated by HPLC and NMR measurements. The femtosecond fluorescence transients are found to be biexponential in nature and the time constants exhibit a significant dependence on solvent viscosity and polarity. A multicoordinate relaxation mechanism is proposed for the excited state relaxation behavior of the model GFP analogs. The first time component (τ(1)) was assigned to the formation of twisted intramolecular charge transfer (TICT) state along the rotational coordinate of N-substituted amine group. Time resolved intensity normalized and area normalized emission spectra (TRES and TRANES) were constructed to authenticate the occurrence of TICT state in subpicosecond time scale. Another picosecond time component (τ(2)) was attributed to internal conversion via large amplitude motion along the exomethylenic double bond which has been enunciated by quantum chemical calculations. Quantum chemical calculation also forbids the involvement of hula-twist because of high activation barrier of twisting. HPLC profiles and proton-NMR measurements of the irradiated analogs confirm the presence of Z and E isomers, whose possibility of formation can be accomplished only by the rotation along the exomethylenic double bond. The present observations can be extended to p-HBDI in order to understand the role of protein scaffold in reducing the nonradiative pathways, leading to highly luminescent nature of GFP.     

Characterization of the mixed self-assembled monolayer at the molecular scale

The mixed SAM obtained by the self-assembly of the monothiolated calix[4]crown-5 receptor 1 and the subsequent addition of the thiolated alkylferrocene guest 3 was characterized at the molecular scale by the favorable receptor-guest interactions by using cyclic voltammetry (CV).     

Rapid Preparation and Easy Quality Control Procedures for 99mTc‐Tin‐Nano Colloid: A Lymphoscintigraphic Agent

^99mTc‐Tin‐nano colloid is a radiopharmaceutical that can be useful in evaluation of the patients with breast cancer. The current method for preparation requires a lengthy boiling water bath procedure, and the recommended quality control procedure is cumbersome and time consuming. Using a microwave oven, the heating time necessary to provide a maximum labeling efficiency has been reduced to 10 second. A new mini paper chromatography (MPC) system has been developed to analyze the radiochemical purity (RCP) of the labeled preparation involving two different developing solvents. The recommended thin layer chromatography (TLC) system involving the use of an Al₂O₃ coated plate requires an average time for drying and development of 34.5 ± 0.44 min (n = 30) to complete, whereas the new MPC system has an average developing time of 2.1 ± 0.2 min (n = 20). For RCP values the MPC and TLC methods are correlated closely (r = 0.94). The combined use of the microwave oven heating method and over quick quality control system will facilitate the rapid emergency use of ^99mTc‐Tin‐nano colloid.     

New aqua rhenium oxocomplex; synthesis,characterization, thermal studies,DFT calculations and catalytic oxidations

The aqua rhenium oxocomplex [ReO(OH)(H₂O)₄]^2? (1) has been prepared and characterized by spectroscopy, thermogravimetry, and elemental analysis and its reactivity towards triphenylphosphine has been evaluated. Complex (1) acts as a catalyst precursor in the presence of molecular oxygen for the oxidation of PPh₃ to OPPh₃. This proceeds through complex intermediates like [Re(PPh₃)_n]³⁺ (2), and [ReO(PPh₃)_n]³⁺ (3). The newly prepared complex (1) was also employed as catalyst for catalytic oxidation of cyclohexane. The geometry of [ReO(OH)(H₂O)₄]^2? has also been optimized in the singlet state by the DFT method with B3LYP level of theory.