Multilayer Films with Nanocontainers: Redox‐Controlled Reversible Encapsulation of Guest Molecules

Stable multilayer films with cucurbit[8]uril have been fabricated on the basis of the alternating layer‐by‐layer assembly of a novel side‐chain pseudopolyrotaxane and a photoreactive polyanion. The as‐prepared multilayer films exhibit good properties as surface‐imprinted multilayers, because cucurbit[8]uril molecules that are locked inside the multilayers can act as nanocontainers with specific binding to certain guest molecules, and the loading and release of the guest is redox‐controllable and reversible.     

Resorcinarene Bis‐Thiacrowns: Prospective Host Molecules for Silver Encapsulation

Mixed‐donor atom tetramethoxy resorcinarene bis‐thiacrown hosts, in which the crown unit contains both hard oxygen and soft sulfur donor atoms, were synthesized for soft metal cation binding. The binding properties were investigated both in solution and in the solid state by NMR spectroscopy and X‐ray crystallography. It was found that the resorcinarene bis‐thiacrowns were able to complex silver cations with remarkable affinity forming readily 1:2 host–guest complexes in solution. The solid state structures also revealed that the bis‐thiacrowns form silver complexes in an unanticipated endo‐ and exo‐cavity fashion within the same host molecule. Both the solution and solid state studies indicated the sulfur atoms to be the major contributing donor atoms in forming the binding interactions with silver cations.     

HZSM-5分子筛中邻近酸中心上的协同催化作用

总结了HZSM-5分子筛中邻近的酸中心协同催化作用的研究进展, 包括布朗斯特酸(B酸)和路易斯酸 (L酸)的协同催化、 B酸和B酸的协同催化作用. 综述了通过多种表征手段下协同催化作用机理的研究进展, 以及实验与理论计算相结合并相互验证的研究结果, 对邻近酸中心协同作用下反应分子的共同吸附、 活化与转化路径的特点进行了分析与总结, 提出了对邻近酸中心协同催化作用进行深入研究的关键科学问题和可能的解决方案.     

Sol–Gel Encapsulation of Molecules to Generate Functional Optical Materials: A Molecular Programming Approach

The extraordinary opportunities offered by integrating solution chemistry of molecular entities with the solid-state nature of the gel provide the basis for designing a number of novel molecular materials. Herein, we present a strategy based on encapsulation of suitable response active species to impart useful optical properties to sol–gel glasses. The basic concept of this molecular programming approach is based on deliberate incorporation of response-active species in the silica gel framework to elicit specific optical responses. Design of molecular materials for device applications depends on selection of molecules which exhibit well-defined electronic or optical response, and assembly of these molecular components into a geometric structure that retains the rigidity, addressability, and stability necessary for practical applications. The approach is based on using molecules as active species and sol–gel glass as structural matrix in which the molecules are selectively integrated. A designer approach that employs specific molecules for generating optical signals is described. As such the properties of these silica-based glasses can be tuned by varying the composition of encapsulated species. These modified glasses exhibit substantially altered optical properties as compared to pristine silica sol–gels. The optical response of these materials provide initial examples toward designing novel materials whose optical and/or photonic responses can be modulated by structural integration of specific dopant entities.     

复合物邻二甲苯…NH3(ND3)分子间的振动

Resonant two photon ionization spectra of S1←S0 transition in complex o xylene…NH3(ND3) in supersonic molecular beam are observed using resonant two photon ionization,together with time of flight mass spectrometry. The spectra exhibit rich information on the complex intermolecular vdW vibrational modes.We have tentatively assigned all the observed spectral features.By analyzing the spectra,the stretching vibrational frequencies and two bending vibrational frequencies of the the complex are obtained.The structure of the complex has been obtained by ab initio computation method.     

Reversible Light‐Driven Polymerization of Polyoxometalate Tethered with Coumarin Molecules

A new photosensitive polyoxometalate (POM) organic–inorganic hybrid compound has been prepared by covalently tethering coumarin moieties onto a Mn–Anderson cluster. This compound has been fully characterized by ¹H NMR, ¹³C NMR, FTIR, and UV/Vis spectroscopy, and ESI‐MS. This organic–inorganic hybrid compound can undergo reversible light‐driven polymerization and this process has been characterized in detail.     

Application of the Monte Carlo Method to Modeling Kinetic Processes of Polyatomic Molecules and Clusters: III. Kinetics of Reversible Reactions of Polyatomic Molecules

The Monte Carlo simulations of the reversible isomerization is carried out. The rate constants for the forward and reverse reaction of dichloroethylene cis–trans isomerization are determined for a broad range of initial conditions. Its is shown that the mutual effect of two actively interacting reactions occurring with energy exchange leads to a number of kinetic features of the process: characteristic changes in the rate constants during the process and the dependence of the equilibrium values of rate constants on pressure. The physical nature of these features associated with the disturbance of the function of distribution over vibrational energy due to the reaction is discussed.     

Encapsulation of Large,Neutral Molecules in a Self-Assembled Nanocage Incorporating Six Palladium(II) Ions

What a large interior space in a molecule! Self-assembled cage compound 1 has a nanosized cavity (8 Å in diameter) and can encapsulate as many as four molecules of o-carborane. A bulky guest, 1,3,5-tri-tert-butylbenzene, once encapsulated by means of thermally activated slippage, cannot escape from the cavity at room temperature since it is larger than the cavity entrance.     

含三氟甲基手性毗邻双螺环氧化吲哚的合成

以10 mol%β-ICD作催化剂,靛红衍生的MBH-碳酸酯与3-(2,2,2-三氟次乙基)氧化吲哚为原料,经不对称[3+2]环加成反应,合成了10个含三氟甲基的手性毗邻双螺环氧化吲哚类化合物(3a^3j),收率68%~98%,dr值97/3~>99/1,ee值96%~>99%,其结构经^1H NMR,^13C NMR确证。     

Palladium(II) Complexes of 1-Phosphaisoprene Molecules and Polymers: Reversible Cross-Linking of a Phosphorus-Containing Polymer

The anionic polymerization of 1-phosphaisoprene [Mes*P=C(Me)−CH=CH₂ (E- 1 )] affords poly(1-phosphaisoprene) 2 in high yield (75 %). Concentrated solutions of polymer 2 (M_n=21,800 g mol⁻¹; Đ=1.02) a P-analogue of natural rubber, undergo gelation upon treatment with [Pd(cod)Cl₂] (0.15 P equiv). Evidence for P-coordination of 2 to Pd^II was obtained by ³¹P and ¹H NMR spectroscopy. The gelation is reversed by the addition of PMe₃ and the reformation of recoverable 2 along with [Pd^II−PMe₃] complexes were confirmed by ³¹P NMR spectroscopy. The use of labile metal-ligand bonds to reversibly form gels is unprecedented and has relevance to self-healing materials. In contrast, coordination of 2 to [Pd(η³-C₃H₅)(μ-Cl)]₂ affords the well-defined complex 2 ⋅ [Pd(η³-C₃H₅)Cl] which was characterized by ³¹P, ¹H, ¹³C{¹H} NMR spectroscopy and GPC. This polymer chemistry was complemented by detailed molecular model studies of the coordination chemistry of monomer 1-phosphaisoprene E- 1 with [Pd(cod)Cl₂] and [Pd(η³-C₃H₅)(μ-Cl)]₂].