Clay-Supported Cu(II) Catalyst: An Efficient, Heterogeneous, and Recyclable Catalyst for Synthesis of 1,4-Disubstituted 1,2,3-Triazoles from Alloxan-Derived Terminal Alkyne and Substituted Azides Using Click Chemistry

<div><p></p><p>A novel series of alloxan-derived 1,4-disubstituted 1,2,3-triazoles was synthesized in excellent yields under catalytic conditions using a click reaction strategy through 1,3-dipolar cycloaddition. Their structures have been ascertained on the basis of spectroanalytical and elemental analysis data. Synthesis of hybrid compounds with varying substitutions in the triazole ring was achieved by reaction between alloxan-derived terminal alkyne and a pertinent azide derivative in the presence of clay-Cu(II) as the catalyst in methanolic medium. Also, comparative evaluation of various catalytic systems [viz., CuI, CuSO₄, CuI-zeolite, K10Ti, and clay-Cu(II)] was investigated. Of these catalytic systems, clay-Cu(II) was observed to be the best. The catalyst was recyclable for several runs without showing significant loss in its activity. The good selectivity, cost-efficiency, short reaction time, milder reaction conditions, and simple workup procedure are the added salient features of this synthetic protocol.</p></div

From Molecules to Devices: A DFT/TD-DFT Study of Dipole Moment and Internal Reorganization Energies in Optoelectronically Active Aryl Azo Chromophores

The present paper elicits a very useful, computational exploration of molecular architectonics of benzothiazole scaffold. The investigation elucidates hopping transport phenomenon in donor–acceptor ensembles lying within a same molecule, comprising an azo group as the core entity. In depth electronic and charge transfer behavior of certain substituted aryl azo benzothiazoles (organic π conjugated) considering notions of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) has been investigated. Moreover, the effect of structural variation in aryl azo moiety (−CF₃, −SCH₃) in presence/absence of solvent has been examined. Also, the impact of disparate solvents namely, polar protic, polar aprotic, and nonpolar solvents has been deduced. Interestingly, results indicate that (<i>E</i>)-2-((4-(trifluoromethyl)­phenyl)­diazenyl)­benzo­[<i>d</i>]­thiazole (BAF) and (<i>E</i>)-2-(phenyldiazenyl)­benzo­[<i>d</i>]­thiazole (BAB) have affirmed to be the promising candidates for the organic charge transfer material in organic light emitting diodes (OLEDs). It was observed that the substituent (−SCH₃) deeply perk up the properties of resulting compound, i.e., (<i>E</i>)-2-((4-(methylthio)­phenyl)­diazenyl)­benzo­[<i>d</i>]­thiazole (BAS) which demonstrated to be an efficient entrant for photovoltaic devices (dye sensitized solar cells (DSSCs)) as dictated by the internal reorganization energies. Furthermore, in order to substantiate these results vis-à-vis to gain a deep insight to consider these molecules as powerful hole/electron carrier mobilizer, their electron density has also been computed. Results obtained by natural bond orbital (NBO) analysis, provide a strong support to the intramolecular charge transfer properties (ICT). An unprecedented explanation of change in the dipole moment substantiates the ICT properties. Besides, HOMO–LUMO gaps, ionization potentials (IPs), electron affinities (EAs), chemical hardness, and light harvesting efficiency (LHE) have been computed to comprehend the nature of the moiety in a more ameliorate way. Also, vibrational findings of BAS placed it as a propitious candidate for <i>in vivo</i> biosensing applications

Hydrogen generation from NaBH₄ hydrolysis using Co-B/AlPO₄ and Co-B/bentonite catalysts

<p>Aluminium phosphate and bentonite supported Co-B catalyst were synthesized via two step impregnation-reduction method for sodium borohydride hydrolysis. The synthesized catalysts were characterized by XRD, FTIR, XPS, FE-SEM, FE-TEM, BET, ICP-AES techniques and tested for NaBH₄ hydrolysis reaction. The results demonstrated that the synthesized supported Co-B catalysts greatly facilitate the NaBH₄ hydrolysis reaction. Highest hydrolysis rate observed for Co-B/AlPO₄ and Co-B/bentonite catalysts are 6.50 and 3.91 L min⁻¹ g⁻¹, respectively, with 2 wt% NaBH₄, 5 wt% NaOH solution at 30 °C. The hydrogen generation rate was found to increase with experimental temperature. Activation energy for the hydrolysis reaction was observed to be 37 and 40.2 kJ mol⁻¹ for Co-B/AlPO₄ and Co-B/bentonite catalysts, respectively.</p

Sustainable Bis-benzoxazines from Cardanol and PET-Derived Terephthalamides

This paper deals with the preparation of sustainable benzoxazines that exhibit enormous potential to compete with the existing petro-based advance performance thermosets. The phenolic component used for the synthesis of benzoxazine is derived from naturally occurring cardanol, which is obtained from cashew nut tree, Anacardium occidentale. Polyethylene terephthalate (PET) was chosen as a sustainable feedstock for the amine fraction used to prepare the benzoxazine monomer containing amide linkages. Microwave-assisted aminolysis of PET was performed to obtain bis­(amino-ethyl) terephthalamide (BAET) and α,ω-aminoligo­(ethylene terephthalamide) (AOET), which were employed as the difunctional amine for the preparation of bis-benzoxazines. In comparison to the traditional method, microwave-assisted aminolysis of PET was found to be significantly faster, and the reaction completion time could be brought down appreciably. Mannich-like condensation of cardanol with PET-derived terephthalamides and paraformaldehyde led to the formation of bis-benzoxazines with amide linkages, the structure of which was confirmed through FT-IR and ¹H NMR spectroscopy. The curing behavior of the bis-benzoxazines was studied using nonisothermal differential scanning calorimetry. The presence of amide linkages in addition to the polar group formed during the ring opening of benzoxazines led to the improvement in adhesive strength, which was quantified in terms of lap shear strength

Sustainable Upcycling of Nitrogen-Enriched Polybenzoxazine Thermosets into Nitrogen-Doped Carbon Materials for Contriving High-Performance Supercapacitors

Nitrogen-enriched polybenzoxazine thermosets derived from the ring-opening polymerization of side-chain-type benzoxazine-functionalized polyethylenimine resins (Bz-pei) have been previously reported by our group. In view of the appreciable nitrogen content and significant char yield, these thermosets have been envisioned as enticing carbon precursors and therefore have been sustainably upcycled to nitrogen-doped carbon materials. It is worth mentioning that the sustainable upcycling method should circumscribe energy as well as cost consumption, due to which carbon materials in the present work have been developed under moderate carbonization conditions, without chemical activation treatment. The developed nitrogen-doped carbon materials have been characterized by using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, elemental analysis, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The pore topography has been analyzed using scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) analysis has been performed, while the Brunauer–Emmett–Teller (BET) surface area has been determined using nitrogen adsorption–desorption experiments. A comparison of the results obtained from electrochemical investigations performed in a three-electrode setup shows that carbon material upcycled from the guaiacol-based polybenzoxazine thermoset, exhibiting 6.4% nitrogen doping in the carbon framework (labeled as C-GP81), exhibits an impressive capacitance of 700 F g–1 at 10 A g–1 current density, suggesting excellent efficiency and rate capability of the obtained N-doped carbon-material-based supercapacitor electrodes. Furthermore, the carbon material designated as C-GP81 could deliver a maximum energy density (Ed) of 48 Wh kg–1 at a power density (Pd) of 8400 W kg–1 in a three-electrode configuration. The performance of the crafted supercapacitor device for the present study has surpassed the performance reported for polybenzoxazine-derived carbons. Additionally, the performance of carbon material labeled as C-GP81 has been evaluated for its potential as an active component in the electrodes of a symmetric device

Acid-Catalyzed, Silica-Supported, One-Pot Benzoylation Route to Synthesize 2-(Substituted Phenyl)oxazolo[4,5-b]pyridines Under Ambient Conditions

<div><p></p><p>The present paper describes a silica-supported, perchloric-acid-catalyzed, efficient protocol for the synthesis of 2-(phenyl)oxazolo[4,5-b]pyridine derivatives. This strategy has high conversion, simple workup procedures, ambient conditions, short reaction times, and a reusable catalyst. Structures of the synthesized compounds have been established on the basis of elemental analysis and spectral data (IR, ¹H NMR, ¹³C NMR, and mass spectrometry). Moreover, to investigate the mechanistic details of the reaction and to ascertain the regioselective outcome of the product, local nucleophilicity descriptors N_k at B3LYP/6-311G++(d, p) level were determined and analyzed.</p></div

Table_1_Genomic profile of SARS-CoV-2 Omicron variant and its correlation with disease severity in Rajasthan.xlsx

BackgroundOmicron, a new variant of Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2), was first detected in November 2021. This was believed to be highly transmissible and was reported to evade immunity. As a result, an urgent need was felt to screen all positive samples so as to rapidly identify Omicron cases and isolate them to prevent the spread of infection. Genomic surveillance of SARS-CoV-2 was planned to correlate disease severity with the genomic profile.MethodsAll the SARS-CoV-2 positive cases detected in the state of Rajasthan were sent to our Lab. Samples received from 24 November 2021 to 4 January 2022 were selected for Next-Generation Sequencing (NGS). Processing was done as per protocol on the Ion Torrent S5 System for 1,210 samples and bioinformatics analysis was done.ResultsAmong the 1,210 samples tested, 762 (62.9%) were Delta/Delta-like and other lineages, 291 (24%) were Omicron, and 157 (12.9%) were invalid or repeat samples. Within a month, the proportion of Delta and other variants was reversed, 6% Omicron became 81%, and Delta and other variants became 19%, initially all Omicron cases were seen in international travelers and their contacts but soon community transmission was seen. The majority of patients with Omicron were asymptomatic (56.7%) or had mild disease (33%), 9.2% had moderate symptoms, and two (0.7%) had severe disease requiring hospitalization, of which one (0.3%) died and the rest were (99.7%) recovered. History of vaccination was seen in 81.1%, of the previous infection in 43.2% of cases. Among the Omicron cases, BA.1 (62.8%) was the predominant lineage followed by BA.2 (23.7%) and B.1.529 (13.4%), rising trends were seen initially for BA.1 and later for BA.2 also. Although 8.9% of patients with Delta lineage during that period were hospitalized, 7.2% required oxygen, and 0.9% died. To conclude, the community spread of Omicron occurred in a short time and became the predominant circulating variant; BA.1 was the predominant lineage detected. Most of the cases with Omicron were asymptomatic or had mild disease, and the mortality rate was very low as compared to Delta and other lineages.</p

Influence of the physicians’ clinical suspicion score of tuberculosis on the frequency of <i>Mycobacterium tuberculosis</i> culture -positive results in active pulmonary and extrapulmonary TB patients according to their HIV status.

<p>NA: not available; AFB: acid fast bacilli; TB: tuberculosis; HIV: Human Immunodeficiency Virus. *TB diagnosis by culture within the group considered. CSTB: clinical suspicion of TB.</p

Comparative proportions of the semi-quantitative smear microscopy results (AFB score) obtained in groups of patients with active pulmonary TB enrolled at the different centers independent of their HIV-status.

<p>AFB: acid fast bacilli.</p>*<p><i>p</i> value of the cumulative group (++ and +++) <i>versus</i> the mean of total enrolled patients with the same AFB score.</p

Analysis of combination of the tests evaluated over 53 active pulmonary TB patients and 82 HCA being concomitantly tested and stratified by HIV status.

<p>Footnotes: HIV: human immunodeficiency virus; TB: tuberculosis; TST: Tuberculin skin test; HCA: healthy community adults; QFT-GIT: QuantiFERON® Gold in Tube (indeterminate results included as negative results); SM: smear microscopy.</p>*<p>X square test was used for statistical analysis.</p