Synthesis of BaZrS3 and BaHfS3 Chalcogenide Perovskite Films Using Single-Phase Molecular Precursors at Moderate Temperatures

Chalcogenide perovskites have garnered interest for applications in semiconductor devices due to their excellent predicted optoelectronic properties and stability. However, high synthesis temperatures have historically made these materials incompatible with the creation of photovoltaic devices. Here, we demonstrate the solution processed synthesis of luminescent BaZrS₃ and BaHfS₃ chalcogenide perovskite films using single-phase molecular precursors at sulfurization temperatures of 575 °C and sulfurization times as short as one hour. These molecular precursor inks were synthesized using known carbon disulfide insertion chemistry to create Group 4 metal dithiocarbamates, and this chemistry was extended to create species, such as barium dithiocarboxylates, that have never been reported before. These findings, with added future research, have the potential to yield fully solution processed thin films of chalcogenide perovskites for various optoelectronic applications.     

Natural Product‐Mimetic Scaffolds with Privileged Heterocyclic Systems: Design,Synthesis, and Evaluation of Antioxidant Activity of Quinazoquinobenzothiazinones

Structurally diverse quinazolinoquinolinobenzothiazinones based on rutaecarpine structural framework with hybrid structural features of three medicinally privileged heterocyclic systems has been synthesized as natural product‐mimetic scaffolds involving the use of multi‐step reaction sequences. The synthesized quinazolinoquinolinobenzothiazinones have been evaluated for their antioxidant and radical scavenging activities.     

High-performance thin-layer chromatographic method for quantitative determination of 4alpha-methyl-24beta-ethyl-5alpha-cholesta-14,25-dien-3beta-ol, 24beta-ethylcholesta-5,9(11),22E-trien-3beta-ol, and betulinic acid in Clerodendrum inerme

A sensitive, selective, precise, and robust high-performance thin-layer chromatography method was developed and validated for analysis of two new recently isolated sterols, 4alpha-methyl-24beta-ethyl-5alpha-cholesta-14,25-dien-3beta-ol (1) and 24beta-ethylcholesta-5,9(11),22E-trien-3beta-ol (2), and a triterpene, betulinic acid (3), in Clerodendrum inerme extract. The method employed HPTLC plates precoated with silica gel 60F(254 )as the stationary phase. To achieve good separation, an optimised mobile phase consisting of toluene-acetone (94:06, v/v) was used (R(f )0.48, 0.34, and 0.22 for compounds 1, 2, and 3, respectively). Densitometric determination of the above compounds was carried out in reflection/absorption mode at 620 nm. Optimised chromatographic conditions provide well separated compact spots for the compounds 1, 2, and 3. The calibration curves were linear in the concentration range of 100-2500 ng/spot. The method was validated for precision, robustness, and recovery. The limits of detection and quantitation were 5, 6, and 10 microg/mL and 14, 18, and 29 microg/mL, respectively, for 1, 2, and 3. The method reported here is reproducible and convenient for quantitative analysis of these compounds in the aerial parts of C. inerme.     

Dynamic Bio-Barcode Assay Enables Electrochemical Detection of a Cancer Biomarker in Undiluted Human Plasma: A Sample-In-Answer-Out Approach

There is a need for biosensing systems that can be operated at the point-of-care (POC) for disease screening and diagnostics and health monitoring. In spite of this, simple to operate systems with the required analytical sensitivity and specificity in clinical samples, using a sample-in-answer-out approach, remain elusive. Reported here is an electrochemical bio-barcode assay (e-biobarcode assay) that integrates biorecognition with signal transduction using molecular (DNA/protein) machines and signal readout using nanostructured electrodes. The e-biobarcode assay eliminates multistep processing and uses a single step for analysis following sample collection into the reagent tube. A clinically relevant performance for the analysis of prostate specific antigen (PSA) in undiluted and unprocessed human plasma: a log-linear range of 1 ng mL⁻¹–200 ng mL⁻¹ and a LOD of 0.4 ng mL⁻¹, was achieved. The e-biobarcode assay offers a realistic solution for biomarker analysis at the POC.     

Steady state and time-resolved fluorescence study of isoquinoline: reinvestigation of excited state proton transfer

In the present work we report some hitherto unnoticed features in the steady state and time-resolved measurements of isoquinoline in water and trifluoroethanol (TFE). Absorption spectra reveal that in water, neutrals as well cationic species are present. Emission spectrum shows structured features at shorter wavelengths accompanied with a broad band around 375 nm, which correspond to neutrals and cations respectively. However, time-resolved data indicate that protonation does not take place in the excited state in water. On the contrary, in stronger hydrogen bonding solvent TFE, distribution of decay components is observed and at longer wavelengths a small rise time is present. This is ascribed to neutral and cation-like species present in the ground as well as in the excited state. The difference in the results is explained in terms of different excited state potential energy surfaces for water and TFE; particularly, the presence of a rather small barrier for protonation in case of TFE.     

Deoxygenative reduction of carbon dioxide to methane, toluene, and diphenylmethane with [Et2Al]+ as catalyst

The strong Lewis acid [Et(2)Al](+) catalyzes the reduction of carbon dioxide with hydrosilanes under mild conditions to methane. In benzene solution, the side products toluene and diphenylmethane are also obtained through Lewis acid catalyzed benzene alkylation by reaction intermediates.     

Raman investigations of Zn1−xCoxO nanocrystals: role of starting precursors on vibrational properties

The Raman spectra of sol–gel derived Co‐doped ZnO nanoparticles (NPs) in the spectral range 100–1500 cm⁻¹ were investigated. In the sol–gel method, three different series of Co‐doped ZnO particles, i.e. Zn_1−xCo_xO (x = 0.05, 0.10, 0.15, and 0.20), were obtained using three different starting precursors, viz. cobalt chloride hexahydrate, cobalt acetate tetrahydrate, and cobalt nitrate hexahydrate, respectively. It has been observed that cobalt acetate is a better precursor in comparison to cobalt chloride and cobalt nitrate to obtain single‐phase Co‐doped ZnO NPs. As for cobalt acetate‐derived NPs, no hidden secondary phase of Co₃O₄ was observed for the lower (x = 0.05) Co concentration. The Fröhlich interaction associated with the longitudinal modes was found to be destroyed with increasing Co concentration due to structural disorder and defects induced by the dopant. In addition to ZnO and Co₃O₄ vibrational modes, a few additional modes near 550 and 715 cm⁻¹ were also observed in all cases, which could be attributed to the modes due to Co doping in ZnO. Copyright © 2011 John Wiley & Sons, Ltd.     

Correlation of CSF neuroinflammatory molecules with leptomeningeal cortical subcortical white matter fractional anisotropy in neonatal meningitis

It has been previously hypothesized that the high fractional anisotropy (FA) values in leptomeningeal cortical subcortical white matter (LCSWM) regions of neonatal brain with bacterial meningitis is due to the presence of adhesion molecules in the subarachnoid space, which are responsible for adherence of inflammatory cells over the subarachnoid membrane. The aim of this study was to look for any relationship between FA values in LCSWM regions and various neuroinflammatory molecules (NMs) in cerebrospinal fluid (CSF) measured in neonates with bacterial meningitis. Diffusion tensor imaging was performed on 18 term neonates (median age, 10.5 days) having bacterial meningitis and 10 age-/sex-matched healthy controls. CSF enzyme-linked immunosorbent assay was performed to quantify NMs [soluble intracellular adhesion molecules (sICAM), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta)]. Significantly increased FA values were observed in LCSWM regions of the patients compared to controls. A significant positive correlation was observed between FA values in LCSWM regions and NMs [sICAM (r=0.67, P=.006), TNF-alpha (r=0.69, P=.005) and IL-1beta (r=0.82, P=.000)] in CSF of these patients. No difference in FA values (P=.99) in LCSWM regions was observed between patients with sterile (0.12+/-0.02) and culture-positive CSF study (0.12+/-0.02). FA may be used as noninvasive surrogate marker of NMs in neonatal meningitis in assessing therapeutic response in future.     

Developments in the synthesis of α,α-dibromoacetophenones and related compounds

Increasing demand of α,α-dibromoketones, as highly reactive and easy-to-handle precursors to carry out selective organic transformations, to synthesize heterocyclic compounds of therapeutic interest and lack of any compilation on this subject prompted us to assemble the methods available for their synthesis.