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Graphyne is a theorized allotrope of carbon. Its structure is one-atom-thick planar sheets of sp and sp2-bonded carbon atoms arranged in crystal lattice. It can be seen as a lattice of benzene rings connected by acetylene bonds. Depending on the content of acetylene groups, graphyne can be considered a mixed hybridization, spn, where 1 < n < 2, and thus differs from the hybridization of graphene (considered pure sp2) and diamond (pure sp3). The existence of graphyne was conjectured before 1960, and attracted attention after the discovery of fullerenes. Although not synthesized yet, periodic graphyne structures and their boron nitride analogues were shown to be stable on the basis of first-principles calculations using phonon dispersion curves and ab-initio finite temperature, quantum mechanical molecular dynamics simulations. Graphdiyne (graphyne with diacetylene groups) has successfully been synthesized on copper substrates. Recently it has been advertised as a concurrent for graphene, due to the potential of direction-dependent Dirac cones. Graphdiyne exhibits a nanoweb-like structure characterized by triangular and regularly distributed pores, which make it look like a nanoporous membrane. In fact, due to the effective size of its pores, which almost matches the van der Waals diameter of the helium atom, graphdiyne could behave as an ideal two-dimensional membrane for helium chemical and isotopic separation. The application of a graphdiyne based membrane as an efficient two-dimensional sieve for water filtration and purification technologies has been also postulated. ==Structure== Graphyne has yet to be synthesized in significant quantities for study but through the use of computer models scientists have been able to predict several properties of the substance on assumed geometries of the lattice. The proposed structures of graphyne are derived from inserting acetylene bonds in place of Carbon-Carbon single bonds in a graphene lattice. Graphyne is theorized to exist in several different geometries. This variety is due to the multiple arrangements of sp and sp2 hybridized carbon. The proposed geometries include a hexagonal lattice structure and a rectangular lattice structure. Out of the theorized structures the rectangular lattice of 6,6,12-graphyne hold the most potential for future applications. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「graphyne」の詳細全文を読む スポンサード リンク
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