No abstract

A high-molecular-weight and well-defined ladder polyphenylsilsesquioxane (Ph-LPSQ) was synthesized via a new three-step approach: monomer self-organization in solution, lyophilization, and surface-confined polycondensation. A ladder superstructure, which served as a template to direct the polycondensation, was self-assembled from the 1,3-diphenyl-tetrahydroxy-disiloxane monomer (M) in acetonitrile solution. Following that, it was lyophilized to form a thin layer on the inner surface of a flask. Subsequently, polycondensation of the ordered monomeric thin layer was performed under a triethylamine (TEA) atmosphere. This strategy increased the ladder regularity of the Ph-LPSQ by preventing common complications faced in solution polycondensation of silanol-containing monomers, such as cyclization and gelation side reactions. 29Si NMR analysis showed a very narrow peak (peak width at half-height, w 1/2 = 2.5 ppm) at δ = –78.5 (corresponding to a Ph-SiO3/2unit), indicating a high degree of regularity of the polymer structure.

A luminescent supramolecular chiral Au16 ring with 4.822 nm perimeter that self-assembled from a tetrameric array of achiral Au2 units is described. Intra- and intermolecular Au...Au interactions play an important role in directing its chiral self-assembly.

Preparation of real ladder polysiloxanes (LPSs), including both oxygen‐bridged ladder polysilsesquioxanes (LPSQs) and organo‐bridged ladder polysiloxanes (OLPSs), had been a great challenge to polymer chemists from 1960 until the successful synthesis of LPSs via the supramolecular architecture‐directed stepwise coupling polymerization (SCP) in the early 1980s. This opened up a new field of LPS‐based advanced materials. As key building blocks, LPSs are used to construct a variety of polysiloxanes with special steric configurations and functions, such as mesomorphic LPSs, tubular polysiloxanes (TPs), and pseudo‐sieve‐plate polysiloxanes (pseudo‐SPSs). With excellent temperature and radiation resistance, good solubility, and fine optical and mechanical properties, all these polysiloxanes demonstrate very promising prospects in the advanced materials realm. Here, the synthesis of well‐ordered LPSs is presented and features of fishbone‐like and rowboat‐like liquid crystalline polysiloxanes are discussed. Special emphasis is given to typical applications of LPSs, TPSs, and pseudo‐SPSs in the areas of liquid crystal displays, microelectronics packaging, and nonlinear optical materials.

A novel soluble aryl amide-bridged ladderlike polymethylsiloxane (A-LPMS) was synthesized by stepwise coupling polymerization on the basis of amido H-bonding self-assembling template from monomer N,N'-bis(3-methyldiethoxylsilylpropyl)-[4,4'-oxybis(benzyl amide)]. The monomer was prepared in a high yield by the hydrosilylation reaction of template agent N,N'-diallyl-[4,4'-oxybis(benzyl amide)] with methyldiethoxysilane in the presence of dicyclopentadienylplatinum dichloride (Cp(2)PtCl(2)) as catalyst. A variety of techniques including (1)H NMR, (13)C NMR, (29)Si NMR, FTIR, XRD, DSC, and, especially, static and dynamic light scattering and viscosimetry were combined to confirm the presence of the ordered ladderlike structure of polymer A-LPMS.

On the rung way: Concerted self‐organization of an α,ω‐bis(triphenylenetetrahydroxy)disiloxane through π–π‐stacking and H‐bonding interactions generates a supramolecular channel in which silanol groups are entrapped between two hydrophobic columns. Ordered polycondensation leads to a high‐molecular‐weight, soluble, ladder cis‐isotactic polysilsesquioxane (see picture).

A novel kind of soluble ladderlike poly(phenylsilsesquioxane) (LPPS) was prepared by stepwise coupling polymerization. Various techniques, such as fluorescence spectroscopy, X‐ray diffraction (XRD), molecular simulation and calculation, were combined to indicate that the steric structure in LPPS was predominantly cis‐isotactic. It is anticipated that stepwise coupling polymerization is a useful synthetic method for preparing ladderlike poly(silsesquioxane)s with cis‐isotactic structure, which have potential applications as functional polymers or as precursors for the further synthesis of novel advanced polymers.

A [3+3] modular self‐assembly gives rise to the formation of a molecular bowl or crown with syn,syn,syn conformation (see picture). These structures are analogues of calix[3]arenes and can function as anion receptors. Interestingly, an NO3− ion is found to distort from a trigonal plane into a trigonal pyramid when binding to the bottom of the molecular bowl.