ChemistryOpen最新文献

This article explores the possible presence of a pentacle valence bond structure in C$$ cyclic molecules. At this end, we have used quantum chemistry tools to elucidate the possible arrangement and the nature of chemical bonds within linear, cyclic, and three-dimensional structures only formed by five carbon atoms. While the linear structure is clearly the most stable one, local minima were obtained for both bi- and three-dimensional structures. Using the localization-delocalization matrices approach, we characterize both the minimum linear structure and the cyclic ones. Interestingly, the linear structure is a combination of ionic and covalent bonds, albeit the four distances are almost identical, when using Density Functional Theory. For cyclic C$$, the pentacle bonding arrangement emerges as a significant Lewis structure, indicative of an unusual formal configuration characterized by five intersecting C−C bonds. Our calculations show that this pentacle arrangement in cyclic C$$ scheme is also present in the more known cyclo-pentadienyl molecule.

Catalytic transformation of CO₂ into value-added chemical products can provide an appropriate solution for the raising environmental issues. To date, various metal-organic frameworks (MOFs) with transition metal ions have been explored for CO₂ capture and conversion, but alkaline earth metal-based MOFs are comparatively less studied. Metal ions like Sr(II) having relatively large radius give rise to a high coordination number resulting in higher stability of the MOFs. Moreover, the introduction of N-rich functional group in organic linker like −NH₂, −CONH− and triazole into MOF backbone enhance their CO₂ capture and conversion efficiency. Herein, the effect of amine group on the catalytic efficiency of MOFs for CO₂ cycloaddition with epoxides under solvent free and ambient conditions are presented. The di-carboxylates, such as 5-aminoisophthalate (AmIP) and 5-bromoisophthalate (BrIP) were utilized to synthesize Sr(II) based MOFs. The Zn(II) MOF was synthesized using tetra-carboxylate containing amide spacer (OAT) and 4-amino-4H-1,2,4-triazole (AMT). All three MOFs exhibited porous networks with guest available volume ranging from 15 to 58 %. The catalytic efficiency of the MOFs towards carbon dioxide fixation reaction was explored. The catalytic performances revealed that the presence of amine group in the channels enhances the catalytic efficiency of the MOFs.

Base-filling, i. e., post-synthetic furnishing of an oligonucleotide scaffold with base moieties or their analogues, is an interesting alternative to the conventional approach of sequential coupling of building blocks (modified or otherwise). Reversible attachment of the base moieties is particularly attractive as it allows the use of dynamic combinatorial chemistry and usually leads to higher fidelity. This concept article summarizes the various backbones and coupling reactions used for base-filling over the past fifteen years, discusses the impact of base stacking and pairing on efficiency and fidelity and highlights potential and realized applications.

This study focuses on six D-π-A systems, utilizing diverse π-spacers as bridges. Comprehensive analysis through Density Functional Theory (DFT) and Time-dependent Functional Theory (TD-DFT) methods at B3LYP using 6-31G (d.p) basis set explores geometrical, electrical, optical, photovoltaic, and absorption properties. E_HOMO, E_LUMO, and energy gap (E_gap), for all of these dyes have been determined and discussed using ground state optimization. TD-DFT calculates optical properties, unveiling enhanced excitation energies and HOMO-LUMO energy levels, indicative of improved electron injection and dye regeneration processes. Examination of energy gap, open-circuit voltage (VOC), free energy change (ΔGinject), light harvesting efficiency (LHE), and absorption spectra reveals D4 dye′s lower Egap and robust absorption in the visible spectrum. Molecular tailoring emerges as a promising technique for optimizing D-π-A sensitizer design, offering potential advancements in DSSCs applications.

Controlling the local concentration of metal complexes at the surface of ionic liquids (ILs) is a highly sought-after objective due to its pivotal implications in supported ionic liquid phase (SILP) catalysis. Equally important is to avoid per- and polyfluorinated substances due to environmental concerns. Herein, we investigate the surface enrichment of Ru polypyridyl complexes with fluorine-free alkylic side groups of varying lengths and shapes, using the hydrophilic IL [C₂C₁Im][OAc] as solvent. Additional charged carboxylate groups are included into the polypyridyl ligands to increase the solubility of the complex in the IL. When the ligand system is functionalized with long and hydrophobic alkyl side chains, the complex predominantly localizes at the IL/vacuum interface, as deduced from angle-resolved X-ray photoelectron spectroscopy. Conversely, in the presence of short or more bulky substituents, no surface enrichment is observed. This buoy-like behaviour with fluorine-free side groups is explored for 0.05 %_mol to 1 %_mol solutions. Intriguingly, surface saturation occurs at approximately 0.5 %_mol, which is beneficial to the efficient operation of catalytic systems featuring high surface areas, such as SILP catalysts.

This study reports the design, synthesis, and antibacterial evaluation of a library of novel polyheterocyclic derivatives featuring a unique fused pyrimidopyridopyrazole moiety. A cyclocondensation reaction between an amino−pyrazolopyridopyrimidine precursor and malonates afforded a series of pyrimidopyridopyrazolopyrimidine derivatives. Further diversification was achieved through nucleophilic cyclocondensation, yielding a collection of complex polyheterocyclic systems encompassing various ring structures. All synthesized compounds were rigorously characterized using spectroscopic techniques and elemental analysis. The antibacterial activity of the newly synthesized compounds was assessed against a panel of Gram-positive and Gram-negative bacteria. Notably, several compounds exhibited promising antibacterial activity, highlighting their potential as leads for the development of novel antibiotics.

Direct 3D printing of liquid metal is difficult to form and easy to destroy. In this paper, we developed a 3D printed composite material consisting of a thermoplastic polyurethane (TPU) matrix and liquid metal (LM) dispersed droplets, and introduced the method for realizing 3D printed devices with this composite material: First, the LM is added to 10~50wt %TPU at 190~200 °C through ultrasonic blending to prepare blended ink. After solid cooling, the LM-TPU composite fiber with a diameter of 600 μm was prepared by Wellzoom desktop extruder at 190 °C at an extrusion speed of 400 mm/min. It has excellent elasticity, with a tensile limit of 0.637 N/m², and the TPU could evenly wrap LM droplets. Finally, the LM-TPU fiber is 3D printed at 240 °C by using a 3D printer, and 2D/3D flexible electronic devices with heating and conductive functions could be prepared. The microcircuit has good electrical conductivity; after adding voltage, the circuit has heat release; it could be used as heating equipment to keep warm and used in various flexible wearable electronic products.

Multicomponent reactions (MCRs) offer a highly useful and valuable strategy that can fulfill an important role in synthesizing complex polysubstituted compounds, by simplifying otherwise long sequences and increasing their efficiency. The total synthesis of selected natural products employing three-component reactions as their common strategic MCR approach, is reviewed on a case-by-case basis with selected targets conquered during the last 15 years. The revision includes detailed descriptions of the selected successful sequences; relevant information on the isolation, and bioactivity of the different natural targets is also briefly provided.

Silver/polymeric vesicle composite nanoparticles with good antibacterial properties were fabricated in this study. Silver nanoparticles (AgNPs) were prepared in situ on cross-linked vesicle membranes through the reduction of silver nitrate (AgNO₃) using polyvinylpyrrolidone (PVP) via coordination bonding between the Ag⁺ ions and the nitrogen atoms on the vesicles. X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis), and transmission electron microscopy (TEM) analyses confirmed the formation of AgNPs on the vesicles. The antibacterial test demonstrated good antibacterial activity against both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) for the produced AgNP-decorated vesicles. The minimum inhibitory concentration (MIC) values of the AgNP-decorated vesicles for E. coli and S. aureus were 8.4 and 9.6 μg/mL, respectively. Cell viability analysis on the A549 cells indicated that the toxicity was low when the AgNP concentrations did not exceed the MIC values, and the wound healing test confirmed the good antibacterial properties of the AgNP-decorated vesicles.