Molecular Assemblies Confined in a Controlled Angstrom-Range Solid Space

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We dispersed four kinds of graphitic angstrom-range spaces : the graphitic slit micropores of heat-treated activated carbon fibers (ACFs), graphitic films of oriented slit-micropores, point defect-induced pore spaces in C60 crystals, and micropore-donated carbon aerogels. Their atomic and pore structures were determined by X-ray diffraction and molecular probe method, respectively. The nano-oriented structure of the pore oriented graphitic film was characterized by atomic force microscopy (AFM). AFM showed that slit-pores have a considerably good mutual orientation. The fine micropore structures were determined by N_2 adsorption at 77 K and He adsorption at 4.2 K In particular, He adsorption was effective for elucidation of ultramicropore structures. The structure of H_2O and CCl_4 confined in a slit-micropore of ACFs having different widths from 0.7 nm to 1.3 nm were determined by in situ X-ray diffraction at the temperature range of -150 to 30ﾟC.The electron radial distribution function of H_2O confined in the micropore at 30ﾟC was completely different from that of bulk liquid water 30ﾟC.The structure of H_2O molecules in micropores did not change even at -150ﾟC.On the other hand, CCl_4 molecules confined in micropores of pore widths except for 1.0 nm had a liquid like structure, but ones in 1.0 nm-width pores had a plastic cystalline structure. The Grand Canonical Monte Calro simulation anticipated this structural anomaly for CCl_4 molecules in micropores of the 1.0 nm width. The activated carbon aerogels had bimodal distribution of uniform mesopores and micropores, of which pore widths can be controlled by the preparation conditions. The pore geometry could be approximated by a cylinder form. The molecular defets in C_<60> crystals could be controlled by the recrystallization and it was shown that a plenty of molecular defects form the connected micropores.