Precision Chemistry最新文献

To develop porous organic frameworks, precise control of the stacking manner of two-dimensional porous motifs and structural characterization of the resultant framework are important. From these points of view, porous molecular crystals formed through reversible intermolecular hydrogen bonds, such as hydrogen-bonded organic frameworks (HOFs), can provide deep insight because of their high crystallinity, affording single-crystalline X-ray diffraction analysis. In this study, we demonstrate that the stacking manner of hydrogen-bonded hexagonal network (HexNet) sheets can be controlled by synchronizing a homological triangular macrocyclic tecton and a hydrogen-bonded cyclic supramolecular synthon called the phenylene triangle. A structure of the resultant HOF was crystallographically characterized and revealed to have a large channel aperture of 2.4 nm. The HOF also shows thermal stability up to 290 °C, which is higher than that of the conventional HexNet frameworks.

Graphdiyne (GDY) science is a new and rapidly developing interdisciplinary field that touches on various areas of chemistry, physics, information science, material science, life science, environmental science, and so on. The rapid development of GDY science is part of the trend in development of carbon materials. GDY, with its unique structure and fascinating properties, has greatly promoted fundamental research toward practical applications of carbon materials. Many important applications, such as catalysis and energy conversion, have been reported. In particular, GDY has shown great potential for application in the field of catalysis. Scientists have precisely synthesized a series of GDY-based multiscale catalysts and applied them in various energy conversion and catalysis research, including ammonia synthesis, hydrogen production, CO₂ conversion, and chemical-to-electrical energy conversion. In this paper, we systematically review the advances in the precisely controlled synthesis of GDY and aggregated structures, and the latest progress with GDY in catalysis and energy conversion.

To rationalize the design of D-π-A type organic small-molecule nonlinear optical materials, a theory guided machine learning framework is constructed. Such an approach is based on the recognition that the optical property of the molecule is predictable upon accumulating the contribution of each component, which is in line with the concept of group contribution method in thermodynamics. To realize this, a Lewis-mode group contribution method (LGC) has been developed in this work, which is combined with the multistage Bayesian neural network and the evolutionary algorithm to constitute an interactive framework (LGC-msBNN-EA). Thus, different optical properties of molecules are afforded accurately and efficiently─by using only a small data set for training. Moreover, by employing the EA model designed specifically for LGC, structural search is well achievable. The origins of the satisfying performance of the framework are discussed in detail. Considering that such a framework combines chemical principles and data-driven tools, most likely, it will be proven to be rational and efficient to complete mission regarding structure design in related fields.

Among the various two-dimensional (2D) materials, more than 99% of them are noncentrosymmetric. However, since the commonly used substrates are generally centrosymmetric, antiparallel islands are usually inevitable in the growth of noncentrosymmetric 2D materials because of the energetic equivalency of these two kinds of antiparallel islands on centrosymmetric substrates. Therefore, achieving the growth of noncentrosymmetric 2D single crystals has long been a great challenge compared with the centrosymmetric ones like graphene. In this review, we presented the remarkable efforts and progress in the past decade, through precise chemical processes. We first discussed the great challenge and possible strategies in the growth of noncentrosymmetric 2D single crystals. Then, we focused on the advancements made in producing representative noncentrosymmetric 2D single crystals, including hexagonal boron nitride (hBN), transition metal dichalcogenides (TMDs), and other noncentrosymmetric 2D materials. At last, we summarized and looked forward to future research on the growth of layer-, stacking-, and twist-controlled noncentrosymmetric 2D single crystals and their heterostructures.

The precise synthesis of subporphyrinoid hybrids with π-expanded topologies and unique material properties plays a promising role in the design of functional macrocycles. Easy, selective, and controllable routes to boron subphthalocyanine–subnaphthalocyanine hybrids, Bsub(Pc_3-p-Nc_p)s, are desirable for this purpose yet synthetically challenging due to random mixtures of C_s-, C_3v-, and, in some cases, C₁-symmetric compounds that form during traditional statistical mixed cyclotrimerizations. Herein, we addressed this issue by developing a sterically driven mixed cyclotrimerization with enhanced selectivity for the targeted C_s-symmetric hybrid and complete suppression of sterically crowded macrocyclic byproducts. This process, coupled with a rationally designed precursor bearing bulky phenyl substituents, enabled the synthesis and characterization of bay-position phenylated Ph₂-(R_p)₈Bsub(Pc₂-Nc₁) hybrids with halogens (R_p = Cl or F) in their peripheral isoindole rings. Reaction selectivity ranged between 59 and 72% with remarkable yields, significantly higher than that of conventional mixed cyclotrimerizations. These findings were augmented by theoretical calculations on precursor Lewis basicity as guiding principles into hybrid macrocycle formation. Additionally, the incorporation of unfused phenyl groups and halogen atoms into the hybrid framework resulted in fine-tuned optical, structural, electronic, and electrochemical properties. This straightforward approach achieved improved selectivity and controlled narrowing of the product distribution, affording the efficient synthesis of structurally sophisticated Bsub(Pc₂-Nc₁) hybrids. This then expands the library of 3-dimensional π-extended macrocycles for use in a range of applications, such as in optoelectronic devices with precisely tailored optical properties.

High selectivity toward alkenes in oxidative dehydrogenation (ODH) of light alkanes makes boron-based materials promising catalysts. However, many key mechanistic aspects are still debated due to the challenge of capturing fleeting reaction intermediates. Kinetic analysis, including determining reaction orders and activation energy, could be informative for reactions involving radical intermediates but has not been extensively exploited. This Review summarizes the current understanding of the apparent alkane reaction order and the apparent activation energy in the boron-catalyzed ODH. Despite varying compositions and structures, a majority of boron-based catalysts share many common features, including alkene selectivity, the evolution and the formation of active site, and the apparent kinetic properties. These common trends could be attributed to the shared gas-phase radical-mediated reaction pathways and the formation of active hydroxylated boron oxide species on boron-containing materials under ODH conditions. Values of apparent alkane reaction orders and apparent activation energies are sensitive and reliable experimental measures of the contributions of the gas-phase radical-mediated and surface-mediated pathways, suggesting the outline of a general mechanistic framework of the boron-catalyzed ODH.