Indium(III) Trifluoromethanesulfonate: a Reusable Catalyst for the Sol-vent-free Synthesis of some Quinazolinones/thiones

An environmentally friendly and clean procedure gives octahydroquinazolinones/thiones by a simple Bigi-nelli condensation of urea/thiourea, aromatic aldehydes, and cyclic 1,3-diones in the presence of indi-um(III) trifluoromethanesulfonate (In(OTf)3) in solventless conditions. This method has advantages such as avoidance of the organic solvents, high yield of pure products without any by-product, short reaction times and operational simplicity.(doi: 10.5562/cca2087

Ultra-stable nanofluid containing Functionalized-Carbon Dots for heat transfer enhancement in Water/Ethylene glycol systems: Experimental and DFT studies

A facile hydrothermal method was applied to synthesize functionalized-carbon dot nanoparticles. The analysis revealed a low crystallinity with amorphous nature for particles with a size below 17 nm, which were functionalized with oxygen (17.9%) and nitrogen (12.2%). A nanofluid was formed by dispersing the nanoparticles in a mixture of water and ethylene glycol. The zeta potential measurement confirmed the stability of the nanofluid (-61.5 mV). Viscosity and density measurements revealed that the suspended nanoparticles did not noticeably increase the viscosity (maximum 8%) and density (maximum 1.2%). The thermal conductivity increased as temperature and nanoparticle concentration increased, and a maximum enhancement of 21% was obtained at 45 °C and 0.5 Wt%. Then, the convection heat transfer was investigated in the turbulent regime. The results showed a remarkable enhancement of the convective heat transfer coefficient (34%) at the Reynolds number of 15529 and 0.5 Wt%. Finally, the density functional theory (DFT) method was applied to interpret the long-term stability of the nanofluid. These results showed that the surface functional groups play a prominent role in the stability of the nanofluids. The calculations indicate that the bonding between the functionalized nanoparticles and the solvent fluid occurs through hydrogen bonds and electrostatic dipolar interactions

A Three-Dimensional Dynamic Supramolecular "Sticky Fingers" Organic Framework.

Engineering high-recognition host-guest materials is a burgeoning area in basic and applied research. The challenge of exploring novel porous materials with advanced functionalities prompted us to develop dynamic crystalline structures promoted by soft interactions. The first example of a pure molecular dynamic crystalline framework is demonstrated, which is held together by means of weak "sticky fingers" van der Waals interactions. The presented organic-fullerene-based material exhibits a non-porous dynamic crystalline structure capable of undergoing single-crystal-to-single-crystal reactions. Exposure to hydrazine vapors induces structural and chemical changes that manifest as toposelective hydrogenation of alternating rings on the surface of the [60]fullerene. Control experiments confirm that the same reaction does not occur when performed in solution. Easy-to-detect changes in the macroscopic properties of the sample suggest utility as molecular sensors or energy-storage materials

Unveiling the impact of laser power variations on microstructure, corrosion, and stress-assisted surface crack initiation in laser powder bed fusion-processed Ni-Fe-Cr alloy 718

Corrosion and stress-corrosion related failures often compromise the integrity of critical metallic components during their service, raising significant concerns. It is crucial to comprehend the crack initiation mechanism and the impact of alloy microstructure on this crack initiation process. It is known that the introduction of unique microstructures through metal additive manufacturing brings new challenges. This study aims to investigate, for the first time, the effects of microstructural alterations resulting from fluctuations in laser power during laser powder bed fusion on the surface cracking initiation mechanism and electrochemical behaviour of Ni-Fe-Cr alloy 718, which is widely used in applications that require exceptional strength and corrosion resistance. To carry out this investigation, microcapillary electrochemical methods were combined with high-resolution techniques (TEM, SEM, AFM). The findings emphasize the existence of an optimal range of process parameters that effectively mitigate corrosion and crack initiation susceptibility. This work demonstrated that slight deviations in laser power from this optimal value result in diverse alterations at the micro and submicron scales. These alterations include increased subgrain width, porosity, dislocation density, density of nanovoids, and distribution of carbides. Importantly, these changes, particularly in dislocation and nanovoid densities caused by minor variations in process parameters, significantly affect the material's susceptibility to corrosion initiation and stress-assisted surface cracking

Playing with the weakest supramolecular interactions in a 3D crystalline hexakis[60]fullerene induces control over hydrogenation selectivity

Weak forces can play an essential role in chemical reactions. Controlling such subtle forces inreorganization processes by applying thermal or chemical stimuli represents a novel synthetic strategyand one of the main targets in supramolecular chemistry. Actually, to separate the differentsupramolecular contributions to the stability of the 3D assemblies is still a major challenge. Therefore,a clear differentiation of these contributions would help in understanding the intrinsic nature as well asthe chemical reactivity of supramolecular ensembles. In the present work, a controlled reorganization ofan hexakis[60]fullerene-based molecular compound purely governed by the weakest van der Waalsinteractions known,i.e.the dihydrogen interaction-usually called stickyfingers-is illustrated. This pre-reorganization of the hexakis[60]fullerene under mild conditions allows a further selective hydrogenationof the crystalline materialviahydrazine vapors exposure. This unique two-step transformation process ismonitored by single-crystal to single-crystal diffraction (SCSC) which allows the direct observation of themolecular movements in the lattice and the subsequent solid-gas hydrogenation reaction

A Three-dimensional Dynamic Supramolecular “Sticky Fingers” Organic Framework

Engineering high recognition host-guest materials is a burgeoning area in basic and applied research. The challenge of exploring novel porous materials with advanced functionalities with the possibility of being largely scalable, prompted us to develop dynamic crystalline structures promoted by soft interactions. Herein, we demonstrate the first example of a pure molecular dynamic crystalline framework held together by means of weak van der Waals interactions. The presented organic fullerene-based material exhibits a non-porous dynamic crystalline structure capable of undergoing single-crystal to single-crystal reactions. Exposure to hydrazine vapors induce structural and chemical changes that evince the toposelective hydrogenation of alternating rings on the surface of the [60]fullerene. Control experiments confirm that the same reaction does not occur when performed in solution. This easily to detect change in the macroscopic properties paves the way for the real application of these materials

A three-dimensional dynamic supramolecular 'sticky fingers' organic framework

Engineering high-recognition host-guest materials is a burgeoning area in basic and applied research. The challenge of exploring novel porous materials with advanced functionalities prompted us to develop dynamic crystalline structures promoted by soft interactions. The first example of a pure molecular dynamic crystalline framework is demonstrated, which is held together by means of weak "sticky fingers" van der Waals interactions. The presented organic-fullerene-based material exhibits a non-porous dynamic crystalline structure capable of undergoing single-crystal-to-single-crystal reactions. Exposure to hydrazine vapors induces structural and chemical changes that manifest as toposelective hydrogenation of alternating rings on the surface of the [60]fullerene. Control experiments confirm that the same reaction does not occur when performed in solution. Easy-to-detect changes in the macroscopic properties of the sample suggest utility as molecular sensors or energy-storage material

Covalent modification of reduced graphene oxide with piperazine as a novel nanoadsorbent for removal of H2S gas

In the present research, piperazine grafted-reduced graphene oxide RGO-N-(piperazine) was synthesized through a three-step reaction and employed as a highly efficient nanoadsorbent for H2S gas removal. Temperature optimization within the range of 30–90 °C was set which significantly improved the adsorption capacity of the nanoadsorbent. The operational conditions including the initial concentration of H2S (60,000 ppm) with CH4 (15 vol%), H2O (10 vol%), O2 (3 vol%) and the rest by helium gas and gas hour space velocity (GHSV) 4000–6000 h−1 were examined on adsorption capacity. The results of the removal of H2S after 180 min by RGO-N-(piperazine), reduced graphene oxide (RGO), and graphene oxide (GO) were reported as 99.71, 99.18, and 99.38, respectively. Also, the output concentration of H2S after 180 min by RGO-N-(piperazine), RGO, and GO was found to be 170, 488, and 369 ppm, respectively. Both chemisorption and physisorption are suggested as mechanism in which the chemisorption is based on an acid–base reaction between H2S and amine, epoxy, hydroxyl functional groups on the surface of RGO-N-(piperazine), GO, and RGO. The piperazine augmentation of removal percentage can be attributed to the presence of amine functional groups in the case of RGO-N-(piperazine) versus RGO and GO. Finally, analyses of the equilibrium models used to describe the experimental data showed that the three-parameter isotherm equations Toth and Sips provided slightly better fits compared to the three-parameter isotherms