SYNTHESIS OF SOME DITHIOCARBAMATE DERIVATIVES AND THEIR ANTIMICROBIAL ACTIVITY

Some new, 2-[(N-substituted aminothiocarbonylthio)acetyl]aminothiazole, N-substituted aminothiocarbonylthioacetylaminodiphenylmethane and 9-[(N-substituted aminothiocarbonylthio)acetyl]aminofluorene derivatives were synthesized by reacting 2-(chloroacetyl) aminothiazole, chloroacetylaminodiphenylmethane, and 9-(chloroacetyl)aminofluorene with secondary amine dithiocarbamate derivatives in acetone respectively. The structure elucidation of the compounds was performed by IR, ¹H-NMR, and FAB⁺-MS spectral data. The substances were tested for their antimicrobial activity.     

Selective extraction of fungicide carbendazim in fruits using β‐cyclodextrin based molecularly imprinted polymers

Considering the importance of developing a new analytical approach for pesticide residue detection for the sake of ensuring food safety, a β‐cyclodextrin based molecularly imprinted polymer was prepared for selective determination of carbendazim. The polymers consist of a porous and hollow structure demonstrating the selective abundant adsorption sites for carbendazim molecule. The selectivity and adsorption capacity of the imprinted polymers were analyzed with dispersive solid‐phase extraction and analyzed with high performance liquid chromatography coupled with ultraviolet. The results of imprinted polymers were higher than non‐imprinted polymers with the maximum adsorption capacity of 3.65 mg/g within 30 min of total adsorption time. The reusability of the imprinted polymers was determined to evaluate its effectiveness and stability, which proved that the polymers lost 10% efficiency within seven consecutive recycles. The developed method displayed good linearity over the concentration range of 0.05–2.0 mg/L. The recovery percentage of 81.33–97.23 with relative standard deviations of 1.49–4.66% was obtained from spiked apple, banana, orange, and peach samples with a limit of detection of 0.03 mg/L and a limit of quantification of 0.10 mg/L (signal to noise ratio = 3/10). The overall performance of the proposed method evident that this technique provided a desirable outcome and it can be used as a convenient approach, as it qualifies the analytical standards.     

DFT-D4 counterparts of leading meta-generalized-gradient approximation and hybrid density functionals for energetics and geometries

Previously, we introduced DFT-D3(BJ)ω B97X-V and ω B97M-V functionals and assessed them for the GMTKN55 database [Najibi and Goerigk, J Chem. Theory Comput. 2018, 14, 5725]. In this study, we present DFT-D4 damping parameters to build the DFT-D4 counterparts of these functionals and assess these in comparison. We extend our analysis beyond GMTKN55 and especially turn our attention to enzymatically catalyzed and metal–organic reactions. We find that B97M-D4 is now the second-best performing meta-generalized-gradient approximation functional for the GMTKN55 database and it can provide noticeably better organometallic reaction energies compared to B97M-D3(BJ). Moreover, the aforementioned DFT-D3(BJ)-based functionals have not been thoroughly assessed for geometries and herein we close this gap by analyzing geometries of noncovalently bound dimers and trimers, peptide conformers, water hexamers and transition-metal complexes. We find that several of the B97(M)-based methods—particularly the DFT-D4 versions—surpass the accuracy of previously studied methods for peptide conformer, water hexamer, and transition-metal complex geometries, making them safe-to-use, cost-efficient alternatives to the original methods. The DFT-D4 variants can be easily used with ORCA4.1 and above.     

Characterization of 60 GHz Multi Quantum well passively mode-locked laser under optical self-injection locking

The quality and pulse compression of the 60 GHz millimeter wave signals generated by 750 μm long InAlGaAs Multi Quantum Well (MQW) passively mode locked laser under free running and optical self-injection locked conditions are experimentally characterized in terms of longitudinal modes under certain bias currents that range from 24 mA to 90 mA. Initially, the MQW laser is characterized in free running condition with no external injection. The measurements reflect that the free spectral range of laser under test is around 61 GHz and exhibit more than 22 lasing modes. The laser is then integrated into low phase noise self-injection locking oscillator by feeding a part of output RF signal back into the laser cavity to enhance passive mode locking. By doing so the microwave line width of our laser is reduced from 900 kHz to 24 kHz with significant increase in output of resultant beat tones which exhibits strong passive mode locking. This is the first time that the free running microwave line width of MQW laser is reduced up to this level. It is evident from our experimental investigation that as we increase the power and phase correlation between different longitudinal modes inside laser cavity through optical self-injection, the strength of the passively mode locked mechanism is significantly increased and the phase noise of radio frequency signal is drastically reduced.     

An interactive weight space reduction procedure for nonlinear multiple objective mathematical programming

To make a decision that is defined by multiple, conflicting objectives it is necessary to know the relative importance of the different objectives. In this paper we present an interactive method and the underlying theory for solving multiple objective mathematical programming problems defined by a convex feasible region and concave, continuously differentiable objective functions. The relative importance of the different objectives for a decision maker is elicited by using binary comparisons of objective function vectors. The method is cognitively easy to use and in test problems has rapidly converged to an optimal solution.     

Organic–inorganic hybrid porous aerogel: efficient catalyst in transesterification reactions

Hybrid silica-based porous aerogels containing propylsulfonic acid and methyl functionalities were prepared by co-condensation route from the corresponding mercaptopropyltriethoxysilane and methyltriethoxysilane precursors using aqueous ammonia as hydrolyzing agent in the absence of any organic templates. The hybrid aerogel was dried under supercritical CO₂ and characterized by SEM, TEM, ¹³C CP-MAS NMR, ²⁹Si MAS NMR, TG/DTA, and nitrogen adsorption/desorption analyses. The hybrid-silica aerogel containing propylsulfonic acid serves as an efficient heterogeneous acid catalyst in transesterification of fatty acid esters with methanol in a batch reactor.     

Cyclometalated Iridium (III) complexes: Recent advances in phosphorescence bioimaging and sensing applications

The phosphorescence bioimaging and sensing applications of Iridium (III) complexes, in particular to subcellular organelle staining as well as sensing of biologically important analytes, have been reviewed here. The bioimaging applications of the metal complexes provide an attractive alternative to fluorescent organic compounds in the construction of biosensors and biolabels because of having certain advantages.     

Dielectric properties of four room temperature ferroelectric and antiferroelectric multi-component liquid crystalline mixtures

Dielectric properties of four recently formulated room temperature multi-component liquid crystalline mixtures with paraelectric (SmA*), ferroelectric (SmC*) and antiferroelectric (SmC*_A) phases have been studied as a function of temperature and frequency. Under planer anchoring condition, dielectric spectroscopy revealed all the characteristic modes: low frequency P_L and high frequency P_H mode in SmC*_A phase, Goldstone mode (GM) in SmC* phase and soft mode (SM) in SmA* phase. Dielectric behaviour has also been studied under the application of DC bias electric field. With bias electric field, we have been able to study the soft mode dielectric behaviour in the SmC* phase. An unknown high frequency mode (X-mode) with and without bias is also observed in SmC* phase. Dielectric results are explained in the light of generalised Landau theory. The mixtures show very high soft mode electroclinic coefficient in the SmA* phase in addition to fast switching in SmC*_A and SmC* phases [30].     

Development of an experimental set‐up for low‐temperature spectroscopic studies of matrix‐isolated molecules and molecular ices using synchrotron radiation

An experimental set‐up for studying photophysics and photochemistry of molecules in an inert gas medium (matrix‐isolated) and in the ice phase at low temperatures has been developed and commissioned at the Photophysics beamline, Indus‐1 synchrotron radiation source. This end‐station uses an in‐house‐developed closed‐cycle cryostat for achieving cryo‐temperatures (～10 K). Synchrotron radiation from the Photophysics beamline is used as the source of UV–VUV photons and the system is equipped with a Fourier transform infrared spectrometer for characterization of the molecular species formed at low temperature. Various individual components of the end‐station like closed‐cycle cryostat, experimental chamber, gas mixing and deposition systems are tested to ascertain that the desired performance criteria are satisfied. The performance of the composite system after integration with the Photophysics beamline is evaluated by recording IR and UV–VUV photoabsorption spectra of sulfur dioxide at low temperatures (10 K), both in the ice phase as well as isolated in argon matrices. Results obtained are in good agreement with earlier literature, thus validating the satisfactory performance of the system. As an off‐shoot of the study, the VUV absorption spectrum of matrix‐isolated SO₂ in argon matrix up to 10.2 eV is reported here for the first time. This experimental end‐station will provide new opportunities to study photon‐induced reactions in molecules of environmental, astrochemical and industrial importance. Details of the design, development and initial experimental results obtained are presented.