Vibrational overtone spectra of chloroanilines--evidence for intramolecular hydrogen bonding in o-chloroaniline

The near infrared vibrational overtone absorption spectra of liquid phase aniline and chloroanilines are reported. The analysis of the observed CH and NH local mode mechanical frequency values shows that intramolecular hydrogen bonding occurs between NH2 group and chlorine atom in o-chloroaniline. This observation supports the conclusion drawn from microwave spectroscopic studies reported earlier.     

Calibrating a J2 plasticity material model using a 2D inverse finite element procedure

Material models are the key ingredients to accurately capture the global mechanical response of structural systems. The use of finite element analysis has proven to be effective in simulating nonlinear engineering applications. However, the choice of the appropriate material model plays a big role in the value of the numerical predictions. Such models are not expected to exactly reproduce global experimental response in all cases. Alternatively, the measured global response at specific domain or surface points can be used to guide the nonlinear analysis to successively extract a representative material model. By selecting an initial set of stress–strain data points, the load–displacement response at the monitoring points is computed in a forward incremental analysis without iterations. This analysis retains the stresses at the integration points. The corresponding strains are not accurate since the computed displacements are not anticipated to match the measured displacements at the monitoring points. Therefore, a corrective incremental displacement analysis is performed at the same load steps to adjust for displacements and strains everywhere by matching the measured displacements at the monitoring points. The stress–strain vectors at the most highly stressed integration point are found to establish an improved material model. This model is used within a multi-pass incremental nonlinear finite element analysis until the discrepancy between the measured and the predicted structural response at the monitoring points vanishes. The J2 flow theory of plasticity is used as a constitutive framework to build the tangent elastic–plastic matrices. The applicability of the proposed approach is demonstrated by solving 2D inverse continuum problems. The comparisons presented support the effectiveness of the proposed approach in accurately calibrating the J2 plasticity material model for such problems.     

New Triazinoindole Bearing Benzimidazole/Benzoxazole Hybrids Analogs as Potent Inhibitors of Urease: Synthesis,In Vitro Analysis and Molecular Docking Studies

Twenty-four analogs based on triazinoindole bearing benzimidazole/benzoxazole moieties (1–25) were synthesized. Utilizing a variety of spectroscopic methods, including ¹H-, ¹³C-NMR, and HREI-MS, the newly afforded compounds (1–25) were analyzed. The synthesized analogs were tested against urease enzyme (in vitro) as compared to the standard thiourea drug. All triazinoindole-based benzimidazole/benzoxazole analogs (1–25) exhibited moderate to excellent inhibition profiles, having IC₅₀ values of 0.20 ± 0.01 to 36.20 ± 0.70 μM when evaluated under the positive control of thiourea as a standard drug. To better understand the structure–activity relationship, the synthesized compounds were split into two groups, “A” and “B.” Among category “A” analogs, analogs 8 (bearing tri-hydroxy substitutions at the 2,4,6-position of aryl ring C) and 5 (bearing di-hydroxy substitutions at the 3,4-position of aryl ring C) emerged as the most potent inhibitors of urease enzyme and displayed many times more potency than a standard thiourea drug. Besides that, analog 22 (which holds di-hydroxy substitutions at the 2,3-position of the aryl ring) and analog 23 (bearing ortho-fluoro substitution) showed ten-fold-enhanced inhibitory potential compared to standard thiourea among category “B” analogs. Molecular docking studies on the active analogs of each category were performed; the results obtained revealed that the presence of hydroxy and fluoro-substitutions on different positions of aryl ring C play a pivotal role in binding interactions with the active site of the targeted urease enzyme.     

Synthesis,In Vitro Anti-Microbial Analysis and Molecular Docking Study of Aliphatic Hydrazide-Based Benzene Sulphonamide Derivatives as Potent Inhibitors of α-Glucosidase and Urease

A unique series of sulphonamide derivatives was attempted to be synthesized in this study using a new and effective method. All of the synthesized compounds were verified using several spectroscopic methods, including FTIR, ¹H-NMR, ¹³C-NMR, and HREI-MS, and their binding interactions were studied using molecular docking. The enzymes urease and α-glucosidase were evaluated against each derivative (1–15). When compared to their respective standard drug such as acarbose and thiourea, almost all compounds were shown to have excellent activity. Among the screened series, analogs 5 (IC₅₀ = 3.20 ± 0.40 and 2.10 ± 0.10 µM) and 6 (IC₅₀ = 2.50 ± 0.40 and 5.30 ± 0.20 µM), emerged as potent molecules when compared to the standard drugs acarbose (IC₅₀ = 8.24 ± 0.08 µM) and urease (IC₅₀ = 7.80 ± 0.30). Moreover, an anti-microbial study also demonstrated that analogs 5 and 6 were found with minimum inhibitory concentrations (MICs) in the presence of standard drugs streptomycin and terinafine.     

Integrated Adsorption–Photodegradation of Organic Pollutants by Carbon Xerogel/Titania Composites

Recent studies on the removal of pollutants via adsorption include the use of carbon-based adsorbents, due to their high porosity and large surface area; however, such materials lack photoactive properties. This study evaluates the synergistic effect of integrated mesoporous carbon xerogel (derived from resorcinol formaldehyde) and titanium dioxide (TiO₂) for combined adsorption and photodegradation application. The complex formed between carbon xerogel and TiO₂ phase was investigated through FTIR, proving the presence of a Ti-O–C chemical linkage. The physicochemical properties of the synthesised adsorbent–photocatalyst were probed using FESEM, BET analysis and UV–Vis analysis. The kinetics, equilibrium adsorption, effect of pH, and effect of adsorbent dosage were investigated. The expansion of the absorbance range to the visible range was verified, and the corresponding band gap evaluated. These properties enabled a visible light response when the system was exposed to visible light post adsorption. Hence, an assistive adsorption–photodegradation phenomenon was successfully executed. The adsorption performance exhibited 85% dye degradation which improved to 99% following photodegradation. Further experiments showed the reduction of microorganisms under visible light, where no microbial colonies were observed after treatment, indicating the potential application of these composite materials.     

Radiosynthesis and Biodistribution of <Superscript>99m</Superscript>Tc-Metronidazole as an <Emphasis Type="Italic">Escherichia coli</Emphasis> Infection Imaging Radiopharmaceutical

Bacterial infection poses life-threatening challenge to humanity and stimulates to the researchers for developing better diagnostic and therapeutic agents complying with existing theranostic techniques. Nuclear medicine technique helps to visualize hard-to-diagnose deep-seated bacterial infections using radionuclide-labeled tracer agents. Metronidazole is an antiprotozoal antibiotic that serves as a preeminent anaerobic chemotherapeutic agent. The aim of this study was to develop technetium-99m-labeled metronidazole radiotracer for the detection of deep-seated bacterial infections. Radiosynthesis of ^99mTc-metronidazole was carried by reacting reduced technetium-99m and metronidazole at neutral pH for 30 min. The stannous chloride dihydrate was used as the reducing agent. At optimum radiolabeling conditions, ~ 94% radiochemical was obtained. Quality control analysis was carried out with a chromatographic paper and instant thin-layer chromatographic analysis. The biodistribution study of radiochemical was performed using Escherichia coli bacterial infection-induced rat model. The scintigraphic study was performed using E. coli bacterial infection-induced rabbit model. The results showed promising accumulation at the site of infection and its rapid clearance from the body. The tracer showed target-to-non-target ratio 5.57 ± 0.04 at 1 h post-injection. The results showed that ^99mTc-MNZ has promising potential to accumulate at E. coli bacterial infection that can be used for E. coli infection imaging.     

Advancements in biocatalysis: From computational to metabolic engineering

Through several waves of technological research and un-matched innovation strategies, bio-catalysis has been widely used at the industrial level. Because of the value of enzymes, methods for producing value-added compounds and industrially-relevant fine chemicals through biological methods have been developed. A broad spectrum of numerous biochemical pathways is catalyzed by enzymes, including enzymes that have not been identified. However, low catalytic efficacy, low stability, inhibition by non-cognate substrates, and intolerance to the harsh reaction conditions required for some chemical processes are considered as major limitations in applied bio-catalysis. Thus, the development of green catalysts with multi-catalytic features along with higher efficacy and induced stability are important for bio-catalysis. Implementation of computational science with metabolic engineering, synthetic biology, and machine learning routes offers novel alternatives for engineering novel catalysts. Here, we describe the role of synthetic biology and metabolic engineering in catalysis. Machine learning algorithms for catalysis and the choice of an algorithm for predicting protein-ligand interactions are discussed. The importance of molecular docking in predicting binding and catalytic functions is reviewed. Finally, we describe future challenges and perspectives.     

An MCl inf4 p2− moiety (M = copper,zinc, cadmium and mercury) stabilized by bis(ethylenediamine)copper(II) cation

Summary New ionic bimetallic complexes of the type [Cu(en)₂]-[MCl₄], where M = Cu^II, Zn^II, Cd^II and Hg^II, were prepared by reacting bis(ethylenediamine)copper(II) dichloride (1 mol) with copper, zinc, cadmium and mercury dichlorides (1 mol) in absolute alcohol. Elemental analyses, conductivity and magnetic susceptibility measurements, and spectroscopic data (such as i.r., u.v.-vis. and e.p.r.) confirm that the compounds are 22 electrolytes in MeOH and that the copper(II) ion is paramagnetic, maintaining its square-planar geometry, while metal ions in the anionic moiety of the complexes achieve their usual tetrahedral environment. An augmented magnetic moment has been observed in the [Cu(en)₂] [CuCl₄] complex, which is attributed to the ferromagnetic effect and TIP.Author to whom all correspondence should be directed.     

The Vibrational Spectra of Some Monosubstituted Phenyl Derivatives of Group VI a Elements

The vibrational frequencies for diphenyl selenide, diphenyl telluride, diphenyl diselenide, diphenyl ditelluride, diphenyl disulfide mercury and diphenyl diselenide mercury have been assigned and were consistent with the vibrational assignments for diphenyl ether, diphenyl sulfide and diphenyl disulfide previously reported. The vibrational assignments for diphenyl telluride confirmed the linearity of the Gordy Rule plot for the t-vibration of Group VI A elements.