Dinuclear gold (I)-di-N-heterocyclic carbene complexes: syntheses,structure, density functional theory calculation and photoluminescence study

The synthesis and characterizations for a series of dinuclear gold (I)-di-NHC complexes, 1–8 through the trans-metalation method of their respective silver (I)-di-NHC complexes, i–viii are reported (where NHC = N-heterocyclic carbene). The successful complexation of a series of unusual non-symmetrical and symmetrical di-NHC ligands, 3,3'-(ethane-1,2-diyl)-1-alkylbenzimidazolium-1'-butylbenzimidazolium (with alkyl = methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, benzyl) with the gold (I) ions are suggested by elemental analysis, Fourier transform-infrared, ¹H- and ¹³C-NMR data. The ¹³C-NMR spectra of 1–8 show a singlet sharp peak in the range of 190.00–192.00 ppm, indicating the presence of a carbene carbon that bonded to the gold (I) ion. From single crystal X-ray diffraction data, the structure of complex 6 with the formula of [di-NHC-Au (I)]₂·2PF₆ is obtained [where NHC = 3,3'-(ethane-1,2-diyl)-1-hexylbenzimidazolium-1'-butylbenzimidazolium]. The photophysical study in solid state of 6 displays an intense photoluminescence with a strong emission maxima, λ_em = 480 nm, upon excitation at 340 nm at room temperature. Interestingly, the emission maximum at 77 K shows a structural character with a strong peak at 410 nm, a medium at 433 nm and a weak at 387 nm, accompanied by a tail band to about 500 nm.     

Effect of solvation on the molecular structure,vibrational assignment,nature of bonding,and the antiviral drug-like potential of troxerutin against HBV proteins

Drugs used in the management of Hepatitis B virus (HBV) infection are largely based on nucleosides or their analogues and these have several side-effects. These drugs only inhibit viral replication, cannot eliminate cccDNA and present with serious long-term effects. Hence, researchers are now searching for potential targets that present with less side-effect and are more effective. The study was aimed at evaluating and comparing the antiviral drug-like potential of troxerutin against various HBV proteins and entecavir. In this study, troxerutin was purified, synthesized and characterized using ¹H NMR, ¹³C NMR and FT-IR. In addition, detailed investigation using density functional theory (DFT), and in-silico molecular docking of troxerutin and entecavir against various HBV proteins were conducted. The spectral analysis (NMR and FT-IR) confirmed the presence of characteristic functional groups with the presence of C–H, C–C and OH bonds/vibrations. Docking result showed excellent binding affinities across all four HBV proteins with the bindings scores for troxerutin (−6.3 to −7.1 kcal/mol) that was similar to those of entecavir (−6.2 to −7.8 kcal/mol). Unlike entecavir, troxerutin did not show any predicted hepatotoxicity but appears to be immunotoxic with an LD₅₀ value of 1000 mg/kg. Given the anti-HBV potential of troxerutin this study has revealed, further in-vivo and in-vitro studies are needed to validate these findings.     

Hydrothermal growth and controllable synthesis of flower-shaped TiO2 nanorods on FTO coated glass

Journal of Sol-Gel Science and Technology - In this study, the hydrothermal method is used for growing and characterization of titanium dioxide (TiO2) nanorods on the fluorine-doped tin oxide (FTO)...     

Determination of nicotinamide by stopped-flow injection method in pharmaceutical formulations

A simple stopped-flow injection system with spectrophotometric detection was proposed for the determination of nicotinamide (NAM) in pharmaceutical formulations. In this system cyanogen chloride formed from the combination of an acidic KSCN with the NaClO streams reacts with injected NAM to form glutaconic aldehyde. Then the product of these three components was coupled with another buffered (pH 3.5) stream of barbituric acid and directed towards the detector. A 45 s after sample injection the pump was stopped for 130 s. During this time the reactants in the flow cell were provided with the required temperature (40 °C) by placing the cell in a home made cell jacket to increase the yield of the polymethine dye product. Eventually, the absorbance of the formed pink color dye was monitored spectrophotometrically at 560 nm and NAM in the concentration range of 1.0–25.0 μg/mL (R = 0.9974 and D.L = 0.5 μg/mL) was determined. The results obtained by this method were compared statistically and agree with those obtained by the method described in the British Pharmacopoeia.     

A true random number generator based on the photon arrival time registered in a coincidence window between two single-photon counting modules

True random number generators are essential components for communications to be confidentially secured. In this paper a new method is proposed to generate random sequences of numbers based on the difference of the arrival times of photons detected in a coincidence window between two single-photon counting modules.     

Multifunctional approaches to provide potential pharmacophores for the pharmacy shelf: Heracleum sphondylium L. subsp. ternatum (Velen.) Brummitt.

Heracleum sphondylium L. subsp. ternatum (Velen.) Brummitt. commonly known as “hogweed” is traditionally used to manage several human ailments. This investigation assessed, for the first time, the enzyme inhibitory properties, antioxidant activity, phytochemical profile, antimutagenic, and antimicrobial potential of the ethyl acetate, methanol, and water extracts of H. sphondylium. We also established the possible interactions of identified phenolic compounds with cholinesterases, amylase, glucosidase, and tyrosinase using in silico docking studies. Chlorogenic acid was found in high amounts in the methanol extract of H. sphondylium. The methanol extract was an effective inhibitor of acetylcholinesterase (1.70 mg galantamine equivalent (GALAE)/g extract) while the ethyl acetate extract showed pronounced inhibitory action against butyrylcholinesterase (1.77 mg GALAE/g extract). The extracts exhibited low inhibition against amylase (0.12-0.84 mmol acarbose equivalent (ACAE)/g extract) and a more pronounced inhibition against glucosidase (2.29–3.65 mmol ACAE/g extract). In silico results showed that rutin and quercetin (-70.4 and -72.2 Kcal/mol, for rutin and quercetin respectively) docked to the enzymatic cavity of acetylcholinesterase but these phenolic compounds showed less affinity with butyrylcholinesterase (-15.0 and -5.2 Kcal/mol, for rutin and quercetin respectively). The extracts did not induce any mutations on the bacterial strains, while they have excellent antimutagenic capacity against well-known mutagens (inhibition values 98%, 97% and 96%). The methanol extract (0.78 mg/ml) showed moderate antifungal activity while the ethyl acetate extract (0.78–3.12 mg/ml) showed weak to moderate antimicrobial activity. This study provides valuable baseline data which might serve for the development of future pharmacophores for the management of human ailments.     

A numerical investigation of the resonance of gas-filled microbubbles: resonance dependence on acoustic pressure amplitude

The general Keller–Herring equation for free gas bubbles is augmented by specific terms to describe the elasticity, viscosity and thickness of the encapsulating shell in ultrasound contrast agent microbubbles. A numerical investigation that analyses the acoustic backscatter from bubbles is employed to identify resonance frequencies that can be compared, for increasing driving pressure amplitude, with linear approximations obtained via analytical considerations. Calculations for bubbles of the size employed in diagnostic ultrasound, between 2 and 6 μm diameter, that are immersed in water and blood and exposed to monochromatic insonation, causing the bubbles to undergo stable cavitation, reveal that the resonance frequency diverges from the linear approximation as the pressure amplitude is increased. The shift in resonance, to lower frequency values, is found to be more pronounced for larger bubbles with the calculated value differing by up to 40% from the linear approximation. The results of this simulation might be potentially useful in preparation of formulations of ultrasound contrast agents with the specifically desired features, such as for instance resonance frequency.     

Determination of nanomole quantities of lower aldehydes by cold-vapour atomic absorption spectrometry

A method is described for the determination of 10–100 nmole of methanal and 20–150 nmole of ethanal and propanal. The method is based on the oxidation of aldehydes to the corresponding acids by mercuric ion which in turn is reduced to elemental mercury, followed by cold-vapour atomic absorption spectrometry. Calibration plots were constructed between the concentration of each aldehyde and absorbance, while the calibration from the conventional cold vapour procedure was used for total aldehydes determination. The method is selective and can be used for aldehyde determination in the presence of ketones, acetals, alcohols, acids, esters, ethers, organic chlorides and epoxides. This simple method is characterised by 98–102% recoveries and standard deviations of 3%.     

New reproducing kernel Hilbert spaces on semi-infinite domains with existence and uniqueness results for the nonhomogeneous telegraph equation

We introduce new reproducing kernel Hilbert spaces on a semi-infinite domain and demonstrate existence and uniqueness of solutions to the nonhomogeneous telegraph equation in these spaces if the driver is square-integrable and sufficiently smooth.     

Lowest electronic states of neutral and ionic LiN

We have investigated the potential energy curves (PECs) of the LiN heteronuclear diatomic molecule, including its ionic species LiN⁺ and LiN⁻, using explicitly correlated multi-reference configuration interaction (MRCI-F12) calculations in conjunction with the correlation consistent quintuple-𝜁 basis set. The effect of core–valence correlation, scalar relativistic effects, and the size of the basis sets has been investigated. A comprehensive set of spectroscopic constants determined based on the above-mentioned calculations are also reported for the lowest electronic states and all systems, including dissociation energies, harmonic and anharmonic vibrational frequencies, and rotational constants. Additional parameters, such as the dipole moments, equilibrium spin-orbit constants, excitation energies, and rovibrational energy levels, are also documented. We found that the three triplet states of LiN, namely, X ³∑⁻, A ³Π, and 2 ³∑⁻, exhibit substantial potential wells in the PEC diagrams, while the quintet states are repulsive in nature. The ground state of the anion also shows a deep potential well in the vicinity of its equilibrium geometry. In contrast, the ground and excited states of the cation are very loosely bound. Charge transfer properties of each of these states are also analyzed to obtain an in-depth understanding of the interatomic interactions. We found that the core–valence correlation has a substantial effect on the calculated spectroscopic constants.