Manipulation of N,O-nucleophilicity: efficient formation of 4-N-substituted 2,4-dihydro-3H-1,2,4-triazolin-3-ones

A new efficient two-step synthesis of 2,4-dihydro-3H-1,2,4-triazolin-3-ones (triazolinones) from readily available amines is reported. Our novel conditions using hexamethyl disilazane, bromotrimethylsilane, and a catalytic amount of ammonium sulfate smoothly cyclize 1-formyl and 1-acetyl semicarbazides to the target triazolinones. This transformation features simultaneous manipulation of N- and O-nucleophilicity as well as differentiation of the nucleophilicity of a urea and an acyl carbonyl.     

Current Trends in the Application of Nanomaterials for the Removal of Pollutants from Industrial Wastewater Treatment—A Review

In the recent decades, development of new and innovative technology resulted in a very high amount of effluents. Industrial wastewaters originating from various industries contribute as a major source of water pollution. The pollutants in the wastewater include organic and inorganic pollutants, heavy metals, and non-disintegrating materials. This pollutant poses a severe threat to the environment. Therefore, novel and innovative methods and technologies need to adapt for their removal. Recent years saw nanomaterials as a potential candidate for pollutants removal. Nowadays, a range of cost-effective nanomaterials are available with unique properties. In this context, nano-absorbents are excellent materials. Heavy metal contamination is widespread in underground and surface waters. Recently, various studies focused on the removal of heavy metals. The presented review article here focused on removal of contaminants originated from industrial wastewater utilizing nanomaterials.     

Electrochemistry and electrogenerated chemiluminescence of twisted anthracene-functionalized bimesitylenes

The electrochemistry, spectroscopy, and electrogenerated chemiluminescence (ECL) of a variety of 2- and 4-fold anthracene-functionalized tetraarylbimesityls, AB1-4, were investigated. AB1-4 compounds contain a bimesityl core with 2- and 4-fold anthracene functionalities, which generate a rigid D(2d)-symmetric structure. Cyclic voltammetry of AB1 and AB2 showed two reversible, closely spaced one-electron transfers for both oxidation and reduction, and that of AB3 and AB4 showed four reversible, closely spaced one-electron transfers for oxidation and reduction in a benzene/acetonitrile solution. The multielectron transfer properties of all four compounds were confirmed by chronoamperometric experiments with an ultramicroelectrode and digital simulations. These serve as models to probe how interacting groups on a molecule affect the energies of successive electron transfers. AB1-4 compounds are highly fluorescent in nonaqueous solvents and display blue-green emission. They produce very strong ECL with emission at 480 nm, near that of the photoluminescence spectra that can be assigned to emission by direct formation of the singlet via the S-route.     

Twisted bimesitylene-based oxadiazoles as novel host materials for phosphorescent OLEDs

The D_2d-symmetric bimesitylene core has been exploited for designing novel host materials required in the construction of phosphorescence-based organic light emitting devices. The oxadiazole-functionalized twisted bimesitylenes are found to exhibit high band gap (triplet energies), and excellent glass transition temperatures and thermal stabilities for ready exploitation as host materials. The electron-transporting ability and respectable luminance efficiencies with triplet dopants (up to 19.0 cd/A) allow oxadiazole-functionalized bimesitylenes as promising materials for phosphorescence-based light emitting devices, namely PHOLEDs.     

A simple, fast, and easy assay for transition metal-catalyzed coupling reactions using a paper-based colorimetric iodide sensor

A paper-based colorimetric iodide sensor (PBCIS) that consists of filter paper treated with starch and an oxidant is developed. It has been employed as a protocol to obtain the extent of conversion of aryl iodides in C-C, C-N, C-O and C-S bond formations, including polymer-supported Heck reactions, by transition metal catalysts such as palladium, nickel and copper.     

Mechanical properties and crystallization of high-density polyethylene composites with mesostructured cellular silica foam

In this study, composites of high-density polyethylene (HDPE) with mesostructured cellular foam (MCF) silicas have been prepared by melt mixing and studied for the first time. Two different MCF silica analogues having different pore size were used, i.e., 12 nm (MCF-12) and 50 nm (MCF-50). The MCF content in the mesocomposites was 1, 2.5, 5, and 10 mass%. All HDPE/MCF-50 mesocomposites exhibited improved mechanical properties compared with neat HDPE, indicating that the mesocellular silica foam particles with the large mesopore size can act as efficient reinforcing agents. On the other hand, the MCF-12 silica with the smaller size mesopores induced inferior mechanical properties, mainly due to the poorer dispersion of the silica particles and the formation of large aggregates. The mesocellular silica foam particles also affected the thermal properties and the crystallization characteristics of HDPE. Crystallization of mesocomposites was faster than that of neat HDPE. Crystallization kinetics was analyzed with the Avrami equation for both isothermal and non-isothermal conditions. For isothermal crystallization, the Avrami exponent increased with increasing crystallization temperature from 2 to 3. In non-isothermal crystallization, the values of the Avrami exponent increased from 3 to 6.3 with decreasing cooling rate. Lower activation energy values of non-isothermal crystallization were calculated using the isoconversional method of Friedman, as well as using the Kissinger’s equation. Finally, the nucleation efficiency of the mesocellular silica foam particles was estimated from data associated with non-isothermal crystallization, according to the method of Dobreva.     

Highly Potential Antifungal Activity of Quantum-Sized Silver Nanoparticles Against Candida albicans

The antifungal activity of polyvinylpyrrolidone (PVP)-stabilized quantum-sized silver nanoparticles (SNPs) against the growth of Candida albicans has been demonstrated in the present study. C. albicans is a known opportunistic human pathogen causing superficial and systemic infections. Research data carried out on C. albicans so far have shown unequivocally that it develops resistance against conventional antifungal drugs and that the infections it causes are difficult to cure with conventional antifungal agents. Hence, it is urgent to find newer materials for the treatment of infections caused by C. albicans that must be safe for the host. PVP-capped SNPs were synthesized, and its surface plasmon band was observed at 410 nm. The growth of C. albicans was markedly inhibited when the cells were incubated with SNP. The minimum inhibitory concentration (MIC) of SNP was determined as 70 ng/ml, and this value is relatively lower when compared with the conventionally used antifungal drugs such as amphotericin B (0.5 μg/ml), fluconazole (0.5 μg/ml), and ketoconazole (8 μg/ml). The viability of SNP-treated cells was checked by measuring the metabolic activity using XTT assay. Field emission scanning electron microscopic (FE-SEM) and transmission electron microscopic (TEM) analyses of the cells treated with SNP have lost the structural integrity to a greater extent.