To efficiently synthesize 4-azaaryl-benzo-fused five-membered heterocycles, the installation of a 2-pyridyl group using carboxyl-directed ortho-C-H activation is indispensable, as it drives decarboxylation and allows for meta-C-H bond alkylation. This protocol's defining features are its high regio- and chemoselectivity, its broad substrate scope, and its excellent functional group tolerance, all achieved under redox-neutral conditions.
It is challenging to precisely regulate the network extension and configuration of 3D-conjugated porous polymers (CPPs), leading to a restricted capacity for systematically adjusting network architecture and exploring its impact on doping efficiency and electrical conductivity. Face-masking straps on the polymer backbone's face, we suggest, are key to controlling interchain interactions in higher-dimensional conjugated materials, in contrast to linear alkyl pendant solubilizing chains, which are unable to mask the face. Cycloaraliphane-based face-masking strapped monomers were employed, demonstrating that the strapped repeat units, in contrast to conventional monomers, effectively mitigate strong interchain interactions, prolong network residence time, modulate network growth, and enhance chemical doping and conductivity in 3D conjugated porous polymers. Due to the straps doubling the network crosslinking density, the chemical doping efficiency increased by a factor of 18 compared to the control non-strapped-CPP. The manipulation of the knot-to-strut ratio within the straps led to the production of CPPs with diverse network sizes, crosslinking densities, and dispersibility limits, while simultaneously impacting the synthetically tunable chemical doping efficiency. The processability difficulty encountered with CPPs has, for the first time, been overcome by the introduction of insulating commodity polymers into their makeup. Conductivity of thin films created from the combination of CPPs and poly(methylmethacrylate) (PMMA) can now be evaluated. The porous network made of poly(phenyleneethynylene) displays a conductivity that is three orders of magnitude less than that of strapped-CPPs.
The process of crystal melting by light irradiation, termed photo-induced crystal-to-liquid transition (PCLT), yields dramatic changes in material properties with high spatiotemporal resolution. However, the multiplicity of compounds demonstrating PCLT is surprisingly low, thereby impeding the further functionalization of PCLT-active materials and a deeper study into PCLT's fundamental principles. We report on a novel class of PCLT-active compounds, heteroaromatic 12-diketones, whose PCLT activity is fundamentally driven by conformational isomerisation. One particular diketone among the studied samples displays a development of luminescence before the crystal undergoes melting. As a result, the diketone crystal manifests dynamic, multi-step fluctuations in luminescence color and intensity during continuous ultraviolet irradiation. The sequential PCLT processes of crystal loosening and conformational isomerization, preceding macroscopic melting, account for the observed evolution of this luminescence. The investigation, employing single-crystal X-ray diffraction structural characterization, thermal analysis, and theoretical calculations on two PCLT-active and one inactive diketone, exhibited weaker intermolecular interaction patterns within the PCLT-active crystal lattices. Our analysis of the PCLT-active crystals uncovered a unique crystal packing pattern, exhibiting an ordered layer of diketone core components and a disordered layer of triisopropylsilyl substituents. The integration of photofunction with PCLT, as demonstrated in our research, sheds light on the fundamental processes of molecular crystal melting, and will contribute to the diversification of molecular design strategies for PCLT-active materials, surpassing current limitations of structures such as azobenzenes.
Fundamental and applied research is strongly focused on the circularity of present and future polymeric materials, as undesirable end-of-life consequences and waste accumulation are global societal concerns. Thermoplastics and thermosets recycling or repurposing stands as an attractive remedy for these issues, however, both options encounter reduced material properties after reuse, alongside the mixed nature of typical waste streams, presenting a roadblock to refining the properties. Dynamic covalent chemistry, when applied to polymeric materials, allows the creation of targeted, reversible bonds. These bonds can be calibrated to specific reprocessing conditions, thereby mitigating the hurdles of conventional recycling. This review analyzes the key attributes of varied dynamic covalent chemistries that facilitate closed-loop recyclability, and further investigates recent synthetic methodologies towards the integration of these chemistries into innovative polymers and existing commodity plastics. We subsequently delineate the interplay between dynamic covalent bonds and polymer network architecture in shaping thermomechanical properties relevant to application and recyclability, emphasizing predictive physical models of network restructuring. Ultimately, we investigate the economic and environmental ramifications of dynamic covalent polymeric materials in closed-loop processing, leveraging data from techno-economic analysis and life-cycle assessment, including minimum selling prices and greenhouse gas emissions. Each segment analyzes the interdisciplinary hurdles in adopting dynamic polymers extensively, and explores new avenues and future directions for circularity in polymer-based materials.
Extensive research in materials science has long focused on cation uptake as a critical area of study. We examine a molecular crystal containing a charge-neutral polyoxometalate (POM) capsule, [MoVI72FeIII30O252(H2O)102(CH3CO2)15]3+, that houses a Keggin-type phosphododecamolybdate anion [-PMoVI12O40]3-. A cation-coupled electron-transfer reaction transpires within the molecular crystal, facilitated by an aqueous solution composed of CsCl and ascorbic acid, used as a reducing agent. Specifically, crown-ether-like pores within the MoVI3FeIII3O6 POM capsule surface capture multiple Cs+ ions and electrons, and Mo atoms are also captured. Utilizing both single-crystal X-ray diffraction and density functional theory, the positions of Cs+ ions and electrons are elucidated. Egg yolk immunoglobulin Y (IgY) The uptake of Cs+ ions exhibits high selectivity from an aqueous solution including various alkali metal ions. Cs+ ions are liberated from the crown-ether-like pores through the application of aqueous chlorine as an oxidizing agent. These findings underscore that the POM capsule uniquely functions as a redox-active inorganic crown ether, distinctly different from the non-redox-active organic counterpart.
A myriad of elements, including the intricacies of microenvironments and the influence of weak interactions, is crucial in determining the supramolecular response. Infected total joint prosthetics We explore the fine-tuning of rigid macrocycle-based supramolecular architectures, resulting from the interplay of their geometric configurations, molecular dimensions, and the impact of guest molecules. Anchoring two paraphenylene-based macrocycles at different sites of a triphenylene derivative yields dimeric macrocycles distinguished by their shapes and configurations. Remarkably, these dimeric macrocycles demonstrate tunable supramolecular interactions with their guest molecules. A solid-state 21 host-guest complex was noted between 1a and the C60/C70 combination, whereas a peculiar 23 host-guest complex, designated as 3C60@(1b)2, was found between 1b and C60. Expanding the realm of novel rigid bismacrocycle synthesis, this work presents a new strategy for creating various supramolecular structures.
The Tinker-HP multi-GPU molecular dynamics (MD) package is expanded with Deep-HP, a scalable solution for integrating PyTorch/TensorFlow Deep Neural Network (DNN) models. Deep-HP elevates the MD capabilities of DNNs by orders of magnitude, enabling nanosecond simulations of 100,000-atom biomolecular systems, and potentially linking DNNs to any standard (FFs) or many-body polarizable (PFFs) force fields. The ANI-2X/AMOEBA hybrid polarizable potential, intended for ligand binding research, now allows for the calculation of solvent-solvent and solvent-solute interactions using the AMOEBA PFF, and the ANI-2X DNN handles solute-solute interactions. GSK690693 inhibitor AMOEBA's physical long-range interactions, explicitly included in ANI-2X/AMOEBA, are handled via a highly efficient Particle Mesh Ewald implementation, ensuring the preservation of ANI-2X's precise solute short-range quantum mechanical description. A user-defined DNN/PFF partition structure allows for hybrid simulations that encompass key biosimulation ingredients, such as polarizable solvents and counterions. AMOEBA forces are primarily assessed, with ANI-2X forces incorporated solely through corrective steps, ultimately leading to an order of magnitude acceleration enhancement compared to standard Velocity Verlet integration. When simulating durations exceeding 10 seconds, we calculate the solvation free energies of charged and uncharged ligands in four different solvents, and also determine the absolute binding free energies of host-guest complexes featured in SAMPL challenges. The average errors for ANI-2X/AMOEBA are examined within the framework of statistical uncertainty, falling within the range of chemical accuracy relative to experimental data. Biophysics and drug discovery research now have access to a pathway for large-scale hybrid DNN simulations, through the Deep-HP computational platform, and at a force-field cost-effective rate.
Transition metal-modified Rh-based catalysts have been extensively investigated for CO2 hydrogenation, owing to their notable activity. Undeniably, a comprehensive understanding of promoters' molecular activities is hindered by the ill-defined structural nature of the heterogeneous catalytic substrates. Via surface organometallic chemistry and the thermolytic molecular precursor strategy (SOMC/TMP), we developed well-defined RhMn@SiO2 and Rh@SiO2 model catalysts in order to analyze the enhancement effect of manganese in CO2 hydrogenation.