Precision Chemistry最新文献

We report the precise design and synthesis of a fluorescent ligand (E)-4-(((2,6-di-(1H-pyrazol-1-yl)-pyridin-4-yl)-methylene)-amino)-N,N-diphenylaniline (bpp-TPA), achieved through the covalent integration of a fluorophore triphenylamine (TPA) with the coordination subunit 2,6-bis-(pyrazol-1-yl)-pyridine (bpp), which provides a N₆ octahedral coordination environment optimized for Fe-(II), allowing us to prepare a mononuclear complex [Fe-(bpp-TPA)₂]·(CF₃SO₃)₂, bpp-TPA-Fe. This complex exhibits a reversible thermally induced spin-state switching with a T _1/2 of 311 K. Meanwhile, the fluorescent intensity of bpp-TPA-Fe intensified distinctly upon spin-state conversion, reaching its maximum emission at 360 K, clearly indicative of a synergistic coupling between the SCO process and luminescent behavior. Benefiting from its carefully engineered intramolecular motional dynamics and donor-acceptor (D-A) molecular architecture, bpp-TPA-Fe simultaneously exhibits pronounced aggregation-induced emission (AIE) and twisted intramolecular charge transfer (TICT) properties. Furthermore, large bathochromic shifts in the emission spectra with the increase in solution polarity are realized in this complex. This work exemplifies a highly precise molecular design strategy to construct multifunctional molecular materials with tunable magneto-optical properties, opening avenues for next-generation smart material applications.

Alkali metal cations (AM⁺) and hydroxide anions (OH^-) intricately influence Pt-catalyzed hydrogen evolution and oxidation reactions (HER/HOR) in alkaline media, a topic of ongoing debate. Here, we systematically investigate their effects using twenty-eight electrolytes with independently varied Na⁺ and OH^- concentrations ranging from 0.001 to 1.0 M. Our studies reveal a strong correlation between electrical double layer (EDL) thickness and HER/HOR rates. Increasing the OH^- concentration positively shifts the potential of zero free charge and enhances the negative surface charge on Pt within the HER/HOR potential regime. This reduces the EDL thickness, strengthens interfacial electric fields, and facilitates water dissociation during HER and H_ad/OH^- recombination during HOR, boosting the corresponding reaction rates. At a fixed pH, increasing Na⁺ concentrations initially reduces the EDL thickness and enhances HER/HOR activity. However, further increasing Na⁺ concentrations beyond 0.1 M paradoxically increases the EDL thickness and suppresses the HER/HOR rates. This counterintuitive behavior is attributed to the formation of ion pairs at the outer Helmholtz plane under high Na⁺ concentration conditions, which weakens the surface electric field and slows the reaction kinetics. At the highest pH 14, the even stronger interfacial electrical field induces partial dehydration of the secondary hydration shell, which adversely impacts the interfacial water structure and suppresses the HER/HOR activities despite a significant decrease in EDL thickness. This study elucidates the intricate effects of Na⁺ and OH^- concentrations on EDL thickness and establishes the critical role of EDL thickness and the surface electric field in modifying the surface water structure and thus the HER/HOR kinetics, providing valuable insights for the design of next-generation electrochemical systems.

Solving the ground state of quantum many-body systems remains a fundamental challenge in physics and chemistry. Recent advancements in quantum hardware have opened new avenues for addressing this challenge. Inspired by the quantum-enhanced Markov chain Monte Carlo (QeMCMC) algorithm, which was originally designed for sampling the Boltzmann distribution of classical spin models using quantum computers, we introduce a quantum-assisted variational Monte Carlo (QA-VMC) algorithm for solving the ground state of quantum many-body systems by adapting QeMCMC to sample the distribution of a (neural-network) wave function in VMC. The central question is whether such a quantum-assisted proposal can potentially offer a computational advantage over classical methods. Through numerical investigations for the Fermi-Hubbard model and molecular systems, we demonstrate that the quantum-assisted proposal exhibits larger absolute spectral gaps and reduced autocorrelation times compared to conventional classical proposals, leading to more efficient sampling and faster convergence to the ground state in VMC as well as a more accurate and precise estimation of physical observables. This advantage is especially pronounced for specific parameter ranges, where the ground-state configurations are more concentrated in some configurations separated by large Hamming distances. Our results underscore the potential of quantum-assisted algorithms to enhance classical variational methods for solving the ground state of quantum many-body systems.

Six-membered N-heterocycles, such as 2-pyridones, are crucial in bioactive compounds and prevalent in natural products and pharmaceuticals, necessitating innovative synthesis approaches. Traditional methods, typically reliant on the transition-metal-catalyzed direct cyclization of alkynes, face limitations in product complexity. This study introduces a [1 + 2 + 3] annulation strategy for synthesizing 2-pyridones, employing anilines and CF₃-ynones through a base-promoted metal-free catalytic system. This method offers a more streamlined approach to generating polysubstituted 2-pyridones, demonstrating enhanced functional group compatibility across substrates compared with existing transformations. The anilines’ adjacent dialkyl amino groups significantly contribute to the reaction, serving as both proton reservoirs and directing groups, facilitating the formation of 2-pyridones. This reaction involves a ring closure/opening sequence, followed by aza-6π-electrocyclization and a C–C bond cleavage-driven aromatization process. The method’s synthetic utility is further validated by its applicability in subsequent transformations, marking an advancement in the synthesis of complex N-heterocyclic compounds.