Acridinylresorcinol host 3 (9-(3,5-dihydroxy-1-phenyl)acridine) forms such adducts as 3.(benzene), 3.(chloroform), 3.0.5(toluene), and 3.(isobutyl benzoate). Modified acridinol host 4 (9-(3,5-dihydroxy-1-phenyl)-4-hydroxyacridine) having an additional OH group on the acridine ring affords such adducts as 4.(benzene), 4.(chloroform), 4.0.5(toluene).0.5(water), 4.(methanol).(water), and 4.(ethyl acetate). In the crystals, hosts 3 and 4 form hydrogen-bonded (O-H...O-H) poly(resorcinol) chains which are linked together via interchain O-H...N hydrogen bonds to give a coordinatively saturated (O-H...O-H...N) 2D net composed of doubly hydrogen-bonded and antiparallel-stacked, self-complementary cyclic dimer 3(2) or 4(2) as a rigidified building block, the otherwise flexible O-H...O-H hydrogen bonds being thereby taken in a cyclophane-like structure. This network turns out to be remarkably well preserved among the above adducts. Guest molecules, which are disordered in many cases, are incorporated in the cavities left. The binding of small polar guests to host 4 is primarily due to hydrogen bonding to the OH group on the acridine ring. The latter therefore acts only as a polarity modifier of preserved cavities. Adduct 3.(benzene), that is, 3(2).2(benzene) readily loses one of two guest molecules bound in each cavity to give a microporous half-filled adduct 3(2).(benzene) which adsorbs 1 mol of benzene to regenerate the starting full adduct without involving a phase change, as confirmed by X-ray powder diffractions and reversible Langmuir-type adsorption/desorption isotherms. The self-complementarity strategy for designing rigid crystal structures is discussed with a particular reference to the possibility of systematic perturbation/variation approaches in crystal engineering.

The formation behavior of organized organo-modified nanodiamond films and polymer nanocomposites has been investigated using nanodiamonds of several different particle sizes and outermost-surface compositions. The nanodiamond particle sizes used in this study were 3 and 5 nm, and the outermost surface contained -OH and/or -COOH groups. The nanodiamond was organo-modified to prepare -OH cations and -COO anions on the outermost surface by carboxylic anion of fatty acid and long-chain phosphonium cation, respectively. The surface of nanodiamond is known to be covered with a nanolayer of adsorbed water, which was exploited here for the organo-modification of nanodiamond with long-chain fatty acids via adsorption, leading to nanodispersions of nanodiamond in general organic solvents as a mimic of solvency. Particle multilayers were then formed via the Langmuir-Blodgett technique and subjected to fine structural analysis. The organo-modification enabled integration and multilayer formation of inorganic nanoparticles due to enhancement of the van der Waals interactions between the chains. Therefore, "encounters" between the organo-modifying chain and the inorganic particles led to solubilization of the inorganic particles and enhanced interactions between the particles; this can be regarded as imparting a new functionality to the organic molecules. Nanocomposites with a transparent crystalline polymer were fabricated by nanodispersing the nanodiamond into the polymer matrix, which was achievable due to the organo-modification. The resulting transparent nanocomposites displayed enhanced degrees of crystallization and improved crystallization temperatures, compared with the neat polymer, due to a nucleation effect.

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Well-dispersed polymer/organo-modified nanodiamond composites were created using crystalline fluorinated polymers as a matrix. All crystalline fluorinated polymers in this study were heat-resistant and became transparent via high-temperature drawing. The polyvinylidene-fluoride-based copolymer had a lowmelting point for a fluororesin and was easy to handle. Both fluorocarbonand hydrocarbon-modified nanodiamond formed well-dispersed nanocomposites in polyvinylidene-fluoride-based fluorocopolymers. The former was prepared due to excellent miscibility, and the latter was obtained by the so-called "nucleation effect". In this case, the nucleation effect was induced by the "epitaxial growth" resulting from the affinity between the end of the polymer chain and the modified chain and the similarity between the crystal structures of the modified-chain molecule and the corresponding polymer. However, fabricating a nanocomposite by combining hydrocarbon-modified fine particles and a fluorinated polymer is not universally feasible, and this system was unique. Ethylene-tetrafluoroethylene and perfluoroalkoxyalkane polymers showing high-melting points cannot form a nanohybrid with hydrocarbonmodified inorganic nanoparticles. In addition, to form a nanocomposite via melt-compounding, the desorption temperature of the modified chain of the outermost surface of the organo-nanodiamond had to be increased. Phosphonic acid containing fluorocarbon chainmodified nanodiamond satisfied all these requirements. The obtained nanocomposite exhibited enhanced physical properties and unique nanodiamond characteristics. POLYM. COMPOS., 40:E842-E855, 2019. POLYMER COMPOSITES-2019 FIG. 1. (a) Diagrams of application development by nanohybridization of several organo-modified NDs and polymers. (b) Schematic illustration of the research strategy in this study.