Aggregate of alkoxy-bridged Re(I)-rectangles as a probe for photoluminescence quenching

Alkoxy-bridged rhenium(I) rectangles [{(CO)(3)Re(mu-OR)(2)Re(CO)(3)}(2)(mu-bpy)(2)] (1, R = C(4)H(9); 2, R = C(8)H(17); 3, R = C(12)H(25); bpy = 4,4'-bipyridine) comprising long alkyl chains form optically transparent aggregates and exhibit luminescence enhancement in the presence of water. The aggregation of Re(I)-rectangle was followed using a light-scattering technique. Presumably, the enhanced luminescence efficiency resulted from restriction of torsional molecular motion in the aggregates. In addition, the rate of bimolecular quenching of Re(I)-aggregates in the triplet excited state by various electron donors (amines) and acceptors (quinones) was efficient. These results indicate that the excited state of aggregated Re(I) surfactants with an electron acceptor and donor facilitate the electron-transfer quenching process after they became preassociated inside the Re(I)-aggregated species. These synthesized compounds may be useful fluorescent materials in optoelectronic applications.     

Analytical expression for transient chronoamperometric current at ultramicroband electrode

Analytical solution of non-steady state chronoamperometric current at ultramicroband electrode is derived. The analytical expression for current (Padé approximant), valid for entire time domain is compared with the analytical and digital simulation data. A satisfactory agreement with the available limiting cases of analytical expressions and digital simulation data is noted. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 10, pp. 1244–1250. The text was submitted by the authors in English.     

In silico based virtual screening and mixed mode QM/MM calculation identifies caffeine scaffold for designing potential inhibitors for tyrosyl tRNA synthetase of Mycobacterium tuberculosis

Aminoacyl tRNA synthetases are novel antibacterial drug target because of their important role in protein synthesis. In this study, we performed high throughput virtual screening of 205883 compounds from Asinex ligand database to identify potential specific inhibitors for Tyrosyl tRNA synthetase of Mycobacterium tuberculosis (MtbTyrRS). Compounds are ranked based on the glide extra precision docking score. It is noted that the top ranked compounds have caffeine scaffold. The top five caffeine analogs are further evaluated for other drug‐like properties. The binding energies of caffeine analogs are estimated using mixed mode quantum mechanics/molecular mechanics calculation. The results show that these caffeine analogs have good absorption, distribution, metabolism, and excretion properties and high binding affinity to the MtbTyrRS. This suggests that caffeine could be a new scaffold for designing inhibitors against Tyrosyl tRNA synthetase of M. tuberculosis. The top five caffeine analogs are also subjected to docking calculations with human cytosolic and mitochondrial Tyrosyl tRNA synthetases to ascertain their specificities toward MtbTyrRS. The comparative docking studies indicate that the top five caffeine analogs are specific for MtbTyrRS. © 2014 Wiley Periodicals, Inc.     

Synthesis of novel benzo naphtho naphthyridines from 2,4-dicloroquinolines

A schematic study on the condensation of 2,4-dichloroquinolines ( 1 ) with 1-naphthyamine ( 2 ) in the presence of CuI as a catalyst to functionalized mono ( 3 ) and di ( 4 ) substituted naphthylamino quinolines was described. Consequently, these mono- and di-substituted amines on polyphosphoric acid-catalyzed cyclization reaction with p-toluic acid and acetic acid to yield the linear benzo[b]naphtho[2,1-g][1,8]naphthyridines ( 5 ) and angular benzo[b]naphtho[2,1-h] naphthyridines ( 6 ) in good yields. In addition to descried the similar synthesis of benzo[g]naphtho [2,1-b][1,8]naphthyridines ( 12 ) and benzo[h]naphtho[2,1-g][1,8]naphthyridines ( 13 ) from 2,4-dichlorobenzo[h]quinoline ( 8 ) with various anilines ( 9 ) through my intermediates ( 10 and 11 ).     

Effect of ZrO2 on the conductivity of PVC-LiAsF6-DBP polymer electrolytes

The preparation and characterization of composite polymer electrolytes PVC-LiAsF₆-DBP for different concentrations of ZrO₂ have been investigated. X-ray and FTIR studies indicate complex formation between the polymer and salt and that the complex remains mainly in the amorphous phase. The electrical conductivity values measured by a.c impedance spectroscopy are found to depend upon the ZrO₂ concentration. The temperature dependence of the conductivity of the polymer films obeys the VTF relation. The conductivity values are presented and the results are discussed.     

The Anti-inflammatory Activiy of Metal Complexes of Heterocyclic Thiosemicarbazones, 2-Substituted Pyridine N-Oxides and 2-Pyridylthioureas

The thiosemicarbazones and their related metal complexes were shown to be potent anti-inflammatory agents in rodents at 8 mg kg⁻¹. They were effective in blocking induced edema and endotoxic shock while blocking both local and central pain processes. The ability of the agents to function as anti-inflammatory agents is multifold. First, Tumor Necrosis Factor-alpha (TNFα) and Interleukin-1 (IL-1) release was markedly reduced by the agents. Second, high-affinity receptor binding on fibroblasts of TNFα and IL-1 was significantly inhibited. Third, cellular events, e.g. lysosomal enzymes of specific cells, such as macrophages, were inhibited and prostaglandin cyclo-oxygenase and leukotriene 5′-lipoxygenase enzymic synthetic rates were significantly reduced, which should cause an overall reduction of the inflammatory process.     

Effect of ceramic oxide on PVC-PMMA hybrid polymer electrolytes

The preparation and characterization of PVC-PMMA-LiBF₄/LiAsF₆-DBP composite polymer electrolytes for different concentrations of ZrO₂ have been investigated. FTIR studies indicate complex formation between the polymers, salt and plasticizer. The electrical conductivity values measured by ac impedance spectroscopy were found to depend upon the ZrO₂ concentration. The temperature dependence of the conductivity of the polymer films seems to obey the VTF relation. The conductivity values are presented and the results are discussed.     

Computer Simulation of Electron Diffraction Studies of Various Microcrystalline Bodies

Electron diffraction of various microcrystalline bodies has been studied and examined by using computer simulation. Diffracted intensity studies indicated that the peak height increases with the scattering factor. First peak of FCC packed and crystalline observed at S = 6.01 Å and for HCP S = 5.0 Å. The amplitude of waves is most probably the same in the distribution function and providing a spectrum of interatomic distances in the crystalline bodies.     

Superfast Synthesis of Stabilized Silver Nanoparticles Using Aqueous Allium sativum (Garlic) Extract and Isoniazid Hydrazide Conjugates: Molecular Docking and In-Vitro Characterizations

Green synthesis of silver nanoparticles (AgNPs) was synthesized from fresh garlic extract coupled with isoniazid hydrazide (INH), a commonly used antibiotic to treat tuberculosis. A molecular docking study conducted with the selected compounds compared with anthranilate phosphoribosyltransferase (trpD) from Mycobacterium tuberculosis. The aqueous extract of garlic was prepared and mixed with silver nitrate (AgNO3) solution for the superfast synthesis of stable AgNPs. INH was then conjugated with AgNPs at different ratios (v/v) to obtain stable INH-AgNPs conjugates (AgNCs). The resulting AgNCs characterized by FTIR spectra revealed the ultrafast formation of AgNPs (<5 s) and perfectly conjugated with INH. The shifting of λmax to longer wavelength, as found from UV spectral analysis, confirmed the formation of AgNCs, among which ideal formulations (F7, F10, and F13) have been pre-selected. The zeta particle size (PS) and the zeta potential (ZP) of AgNPs were found to be 145.3 ± 2.1 nm and −33.1 mV, respectively. These data were significantly different compared to that of AgNCs (160 ± 2.7 nm and −14.4 mV for F7; 208.9 ± 2.9 nm and −19.8 mV for F10; and 281.3 ± 3.6 nm and −19.5 mV for F13), most probably due to INH conjugation. The results of XRD, SEM and EDX confirmed the formation of AgNCs. From UV spectral analysis, EE of INH as 51.6 ± 5.21, 53.6 ± 6.88, and 70.01 ± 7.11 %, for F7, F10, and F13, respectively. The stability of the three formulations was confirmed in various physiological conditions. Drug was released in a sustainable fashion. Besides, from the preferred 23 compounds, five compounds namely Sativoside R2, Degalactotigonin, Proto-desgalactotigonin, Eruboside B and Sativoside R1 showed a better docking score than trpD, and therefore may help in promoting anti-tubercular activity.