Spectroscopic properties of the molecular ions BeX+ (X=Na,K, Rb): forming cold molecular ions from an ion–atom mixture by stimulated Raman adiabatic process

In this theoretical work, we calculate potential energy curves, spectroscopic parameters and transition dipole moments of molecular ions BeX⁺ (X=Na, K, Rb) composed of alkaline ion Be and alkali atom X with a quantum chemistry approach based on the pseudopotential model, Gaussian basis sets, effective core polarisation potentials and full configuration interaction. We study in detail collisions of the alkaline ion and alkali atom in quantum regime. Besides, we study the possibility of the formation of molecular ions from the ion–atom colliding systems by stimulated Raman adiabatic process and discuss the parameters regime under which the population transfer is feasible. Our results are important for ion–atom cold collisions and experimental realisation of cold molecular ion formation.     

Modulating opto-electronic and magnetic responses of Mo- and Zn-adsorbed LiNbO3 (1 1 1) surface for advanced energy harvesting applications: A comprehensive study

This study aimed to comprehensively investigate the optoelectronic and magnetic properties of Mo, Zn/LiNbO₃ (1 1 1) material. The primary objectives were to understand the potential for manipulating the material's magnetism and to elucidate the origin of spin-polarized states and magnetic moments, particularly with respect to the unpaired d orbitals of Nb, Mo, and Zn atoms. To achieve these objectives, we employed the Pardew–Burke–Ernzerhof (PBE) method within the Generalized Gradient Approximation (GGA + U) framework. This computational approach allowed us to examine the optoelectronic and magnetic characteristics of the material in detail. Our research yielded several key findings that enhance our understanding of Mo, Zn/LiNbO₃ (1 1 1) material. We observed a modest improvement in the material's absorption capacity within the visible spectrum, accompanied by a discernible red-shift. Notably, our study involved the calculation of the dielectric function and refractive constant of the material, revealing a strong correlation between absorption trends and the dielectric constant. Furthermore, our investigation uncovered that Mo, Zn/LiNbO₃ (1 1 1) exhibits distinct conduction and valence bands, with p and d orbitals predominantly contributing to each, respectively. The energy gap of the material falls within a range of 0.30–1.04 eV. A particularly significant finding was the narrower band gap of Mo, Zn/LiNbO₃ (1 1 1) material, which can be attributed to the superposition of Mo-d and Zn-p orbit energy levels with O-p orbit energy levels, ultimately forming a covalent bond. Importantly, our research demonstrated the material's heightened optical absorption within the visible spectrum, suggesting its suitability for various photonic and optoelectronic applications. Additionally, we calculated a wide range of optical characteristics, including the dielectric function, absorption coefficient, energy loss, reflectivity, refractive index, extinction coefficient, and optical conductivity, providing a comprehensive assessment of the material's optical properties.     

In vivo encapsulation of nucleic acids using an engineered nonviral protein capsid

In Nature, protein capsids function as molecular containers for a wide variety of molecular cargoes. Such containers have great potential for applications in nanotechnology, which often require encapsulation of non-native guest molecules. Charge complementarity represents a potentially powerful strategy for engineering novel encapsulation systems. In an effort to explore the generality of this approach, we engineered a nonviral, 60-subunit capsid, lumazine synthase from Aquifex aeolicus (AaLS), to act as a container for nucleic acid. Four mutations were introduced per subunit to increase the positive charge at the inner surface of the capsid. Characterization of the mutant (AaLS-pos) revealed that the positive charges lead to the uptake of cellular RNA during production and assembly of the capsid in vivo. Surprisingly, AaLS-pos capsids were found to be enriched with RNA molecules approximately 200-350 bases in length, suggesting that this simple charge complementarity approach to RNA encapsulation leads to both high affinity and a degree of selectivity. The ability to control loading of RNA by tuning the charge at the inner surface of a protein capsid could illuminate aspects of genome recognition by viruses and pave the way for the development of improved RNA delivery systems.     

Observation of superparamagnetism to flux closure behaviour in ZnO nanoparticle agglomerates

In this paper we have tried to understand the nature of magnetism in ZnO nanoparticle samples with an intrinsic 50?ppm trace of Fe impurity. When the samples are annealed we observe formation of nanoparticle agglomerates and the size increases with annealing temperature. When the sample is annealed at 600?°C we observe superparamagnetic behaviour, and the magnetic hysteresis along with the coercive field below the blocking temperature is almost independent of the cooling field. When the sample is annealed at 900?°C we observe reduction of saturation magnetization but the magnetic hysteresis and the coercive field are now dependent on the cooling field, indicating magnetic correlation and ordering within the agglomerated nanograins. We propose a simple model that explains the reduction of magnetization as being due to a vortex-state-like flux closure formation.     

Abnormal N-heterocyclic carbene palladium complex: living catalyst for activation of aryl chlorides in Suzuki-Miyaura cross coupling

Palladium complexes bearing abnormal N-heterocyclic carbene were used as catalysts in Suzuki-Miyaura cross coupling of aryl chlorides at 25 °C. The catalyst remained active for 10 successive catalytic runs and can activate 4-chlorotoluene at 25 °C with 0.01 mol% catalyst loading resulting in a TON of 9500 within 6 h.     

Kinetic Analysis and Optimization for the Catalytic Esterification Step of PPT Polymerization

Summary: A well‐validated kinetic scheme has been studied for PPT, poly(propylene terephthalate) polymerization process in batch and semi‐batch mode with tetrabutoxytitanium (TBOT), a proven catalyst. Optimization study and analysis for PPT are rare, as the industrial relevance of PPT just became vibrant due to the commercial availability of one of its monomers in industrial scale in the recent past. Correctness of the analysis is checked by a new approach and parameters for the model are estimated from available experimental data. Solubility of terephthalic acid (TPA) is less in reaction medium and this effect is also considered along with the reaction scheme. Several simulations have been performed to see various process dynamics and this ultimately helps in formulating optimization problems. Using recently developed and well tested real‐coded non‐dominated sorting genetic algorithm‐II, a state‐of‐the art evolutionary optimization algorithm, a couple of three objective optimization problems have been solved and corresponding Pareto sets are presented. Results show remarkably promising aspects of productivity enhancement with an improvement in product quality. Sensitivity analysis for relatively uncertain solubility parameter is also performed to estimate its effect over the proposed optimal solutions.

Multiobjective Pareto front for 3 objectives: degree of polymerization, time and (bTPA + bPG).     

Rhodium(III) complexes of 1-Alkyl-2-{(o-thioalkyl) phenylazo}imidazoles: synthesis,structure, spectral characterization,DNA binding study and DFT calculation

Transition Metal Chemistry - The Rh(III) complexes of 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazole (SRaaiNR′, 1; R = R′= Me (a); R = Me, R′= Et...     

Two-photon fluorescent probe for hydrogen sulfide based on a red-emitting benzocoumarin dye

Hydrogen sulfide (H₂S) is an endogenous gasotransmitter and plays intriguing biological roles. To study the biological role of H₂S, efficient fluorescent probes are in great demand. For imaging of H₂S in deep-tissue, a two-photon probe that emits in the red wavelength region is of choice to avoid the autofluorescence from intrinsic biomolecules. Here, we disclose such a probe, which, developed based on an acetyl benzocoumarin fluorophore, can be excited at 900?nm under two-photon excitation and emit in the red region. The probe shows high reactivity, selectivity, and sensitivity in in vitro assays. Two-photon microscopic imaging of H₂S in HeLa cells aided by the probe demonstrates that it is potentially useful to study H₂S level changes in cells and tissues influenced by external stimuli.     

In situ 1,3-dipolar azide cycloaddition reaction: synthesis of functionalized d-glucose based chiral piperidine and oxazepine analogues

Functionalized furanose-fused piperidines 4-6 and oxazepines 15-17, useful precursors for structurally unique bioactive nucleosides as well as for potential glycosidase inhibitors, have been synthesized by the application of 1,3-dipolar azide cycloaddition (DAC) reaction on d-glucose based substrates. The strategy works well even with the nucleoside analogue 8, affording the bicyclic nucleoside analogues 11 and 12.