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The discovery of new and functional macrocyclic host compounds is an important part of supramolecular chemistry. Since the experimental synthesis, prism[n]arenes (Pr[n]As), a class of naphthol‐based macrocyclic arenes, have attracted much attention. In this work, from the perspective of theoretical calculation and research, Pr[n]As (n = 4 ~ 7) were studied by density functional theory (DFT) calculations and molecular dynamics (MD) simulations. The prismatic configuration isomers, electronic structures, absorption spectra, and host‐guest chemistry were discussed thoroughly. DFT calculation results showed that 1,5‐, 3,7‐, and "hybrid" 15,37‐Pr[n]As were the most representative configurations with the rigid prismatic molecular skeleton. Based on time‐dependent density functional theory (TD‐DFT), the absorption spectra of Pr[n]As were all in the range of ultraviolet light which were mainly attributed to π‐π* transitions. The molecular cavities of Pr[n]As were electron‐rich and capable of accommodating a variety of cations or electron‐conjugated molecules. MD simulation results showed that a Pr[n]A molecule was able to capture the guest molecule into its molecular cavity and maintain in the state of equilibrium in solvents. [ABSTRACT FROM AUTHOR]

Background: Safflower (Carthamus tinctorius L.) is an important economic crop and a traditional medicinal material rich in flavonoids, which can alleviate cardiovascular and cerebrovascular pathologies. Thus, many candidate genes involved in safflower flavonoid biosynthesis have been cloned. However, owing to the lack of a homologous gene expression system, research on gene function is limited to model plants. Therefore, a gene function identification protocol for safflower must be established. Results: In the present study, using safflower callus as the experimental material, Agrobacterium and biolistic transient expression systems were established. In the Agrobacterium transient expression system, the highest transformation rate was obtained at the original Agrobacterium concentration of OD600 0.4, infiltration concentration of OD600 0.6, infection for 20 min, co-culture for 3 days, and acetosyringone concentration of 100 μmol·L−1. In the biolistic transient expression system, the highest transformation efficiency was observed at helium pressure of 1,350 psi, vacuum degree of -0.8 bar, flight distance of 6.5 cm, one round of bombardment, plasmid concentration of 3 μg·shot−1, and gold particle concentration of 100 μg·shot−1. Further, these two transient expression systems were used for the functional analysis of CtCHS1 as an example. After overexpression, relative CtCHS1 expression increased, particularly in Agrobacterium-transformed calli. Additionally, the contents of some flavonoids were altered; for instance, naringenin and genistein levels were significantly increased in Agrobacterium-transformed calli, whereas luteolin, luteolin-7-O-rutinoside, and apigenin derivative levels were significantly decreased in biolistic-transformed calli. Conclusion: Using safflower callus as the experimental material, highly efficient Agrobacterium and biolistic transient expression systems were successfully established, and the utility of both systems for investigating gene function was demonstrated. The proposed safflower callus transient expression systems will be useful for further functional analyses of flavonoid biosynthetic genes in safflower. [ABSTRACT FROM AUTHOR]

• The homogenous and hybrid configurational isomers of pagoda[ n ]arenes are proposed and obtained by DFT calculations. • Electronic structure analysis reveals the π-electron rich nature within molecular cavity of pagoda[ n ]arenes. • Pagoda[ n ]arenes are able to accommodate various electron-deficient or organic conjugated guests besides cations. Studies on the synthesis, characterization, and applications of new macrocyclic host species have greatly promoted the development of supramolecular chemistry. Recently, pagoda[ n ]arenes (Pa[ n ]As), a class of anthracene-based macrocyclic arenes, were reported by Chen's group. Pa[ n ]As are inherently endowed with many fascinating properties. In order to fully understand Pa[ n ]As and expand their potential applications, the structures, properties, and supramolecular chemistry of Pa[ n ]As are systematically studied by using a computational approach. Based on density functional theory (DFT) calculations, nine homogenous Pa[ n ]As (n = 4∼6) and six hybrid Pa[4]As are discussed in detail because of their rigid pagoda molecular frameworks and their lower energies. The frontier molecular orbitals and electrostatic potential maps reveal the nature of their electronic structures. Correspondingly, UV–vis spectra are predicted by time-dependent (TD)-DFT calculations. Moreover, Pa[ n ]A molecules are capable of forming host‒guest complexes and self‒assemblies by noncovalent interactions. H-bonding, ion···pi, C H···pi, and van der Waals (vdW) interactions are addressed with the reduced density gradient (RDG) analysis. Finally, molecular dynamics (MD) simulations in the solvent show that Pa[ n ]As are able to recognize guests and maintain a dynamic equilibrium in the form of host-guest complexes. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The lowest-energy conformations of thiapillar[5]arenes are obtained by DFT calculations. • Electronic structure analysis reveals the evolution from electronegativity to electropositivity in the molecular cavities of thiapillar[5]arenes. • Thiapillar[5]arenes are able to accommodate various guests based on the electronic complementarity and the spatial matching. • The sulfur-containing derivatizations of pillar[ n ]arenes are expected to expand the application prospects in supramolecular biology and electrochemistry related fields. The chemical modification of bridging groups of the pillar[ n ]arenes is an important way to functional derivatization and expand the application fields. So far, however, there have been few reports on this issue. On the basis of experimental reports, a series of thiapillar[5]arene structures with sulfur, sulfoxide and sulfone as bridging groups are proposed in this work. By using density functional theory (DFT) calculations, thiapillar[5]arenes are studied systematically at the ωB97XD/6-311G(d,p) level of theory. All the structures have regular pentagonal shape with the point group of D 5. The substitution of bridging methylene by sulfur leads to a significant enlargement in the molecular cavity, an extension of the spatial delocalization of the electrons, and a redshift of the absorption spectrum. The bridging groups of sulfoxide and sulfone can greatly improve the solvent effects in polar solvents, which is followed by the weakening of the pi-electron donating capacity inside the molecular cavity. Thiapillar[5]arenes have rich host–guest chemistry and can recognize a variety of guest species. Interestingly, the inclusion of thiapillar[5]arenes to ferrocene is a synergistic result of electronic and spatial effects. The sulfur-containing derivatizations of pillar[ n ]arenes are expected to expand the application prospects in supramolecular biology and electrochemistry related fields. [ABSTRACT FROM AUTHOR]

A detailed mechanism investigation of the formation of B−N, Si−N and C−N bonds is conducive to the design and synthesis of siliconboroncarbonitride (SiBCN) ceramics to meet application requirements under extreme conditions. Boron trichloride (BCl3), methyldichlorosilane (MDCS) and methylvinyldichlorosilane (MVCS) are the most commonly used raw materials, and they can react with amino compounds, such as ammonia (NH3), methyl ammonium (CH3NH2), and hexamethyldisilazane (HMDZ, (CH3)6Si2NH) in the synthesis of SiBCN precursors. In this paper, quantum chemical calculations were used to study the ammonolysis mechanism of three raw materials with three amino compounds at the M06‐2X/6‐311G(d,p) level of theory. The structural properties, reaction pathways, energy barriers, reaction rates, and other aspects were discussed in detail. The results show that compounds containing B−N, Si−N and C−N bonds can be formed through a synergistic reaction mechanism with the release of ammonium chloride or trimethylchlorosilane (TMCS). The ammonolysis processes of BCl3 have absolute advantages in both kinetics and thermodynamics. The reaction of MDCS has the lowest energy barrier. All ammonolysis reactions are thermodynamically exothermic processes. The calculated results agree well with the experimental observations and provide an explanation for the initiation process of precursor synthesis. [ABSTRACT FROM AUTHOR]

Safflower (Carthamus tinctorius L.) is cultivated in various countries for the flavonoid compounds it contains. These flavonoids have been used in many industries as drugs and/or dyes. Over 60 flavonoids have been isolated from safflower. These flavonoids can be divided into two groups: special and common, both of which are active pharmaceutical ingredients efficacious in the treatment of cardiovascular and cerebrovascular diseases. Gene functions have been studied to figure out the biosynthesis of flavonoids in safflower. However, there is no comprehensive summary of the flavonoids in safflower. Research was recognised through systematic searches of ScienceDirect, PubMed, Web of Science, and CNKI databases by searching terms of " Carthamus tinctorius L.", "safflower", "flavonoid", "pharmacology", and "gene". More than 200 research reports were included after eligibility checks. This study summarizes the application of flavonoids in medicine and other industries. Comprehensively collects the chemical structure information of the two groups of flavonoids, and organic acids, alkaloids, spermidine, polyacetylene, and polysaccharides. The mechanism of two groups of flavonoids in treatment of cardiovascular and cerebrovascular diseases was describe in detail, and pharmacological mechanisms of protecting liver, lung and bone, and anti-cancer and anti-inflammatory were also summarised. Besides, the study updated the latest information on the molecular biology of safflower flavonoids. It is found that two groups of flavonoids in safflower have obvious differences in application, chemical structure, pharmacological mechanism, and biosynthetic pathway. It is hoped that this summative research will provide a new insight to flavonoids research in safflower. [Display omitted] • Flavonoids in safflower classified into two into two groups according to chemical structure in this review. • There are differences in the mechanisms of the two groups of flavonoids in improving cardiovascular and cerebrovascular diseases. • Research progress on special flavonoids' biosynthetic pathway in safflower was analysed. [ABSTRACT FROM AUTHOR]