An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Poster SessionsNano-ball allophane is a naturally occurring aluminum silicate mineral with hollow spherical morphology.Diameter of the mineral is observed as 3.5 to 5.0 nm with TEM, and cation exchange experiments have proven the existence of some pores along the spherule wall.Chemical structure of the wall is similar to that of imogolite with nano-tube structure, where orthosilicates are bonded inside of gibbsite vacant site (imogolite sheet).However, whole chemical structure of the nano-ball has not been clarified.We succeeded to tentatively construct the whole chemical structure of the ball by assuming an expanded truncated octahedron composed of hexagonal imogolite sheets.By changing size of the imogolite sheets, diameters of the ball become 1.5 nm, 3.0 nm, 4.5 nm, and so on.Here we present full-structural optimization results for the nano-ball with diameter of 1.5 nm.Gaussian 03 for UNIX revision C.01 with HF/6-31G(d) method was used for calculations.The 6-coordinated Al and the 4-coordinated Si atom in the optimized structure were stable and no change in its ball shape structure.The calculated O・・・O atom distance in the vacant octahedral site that is substituted with orthosilicate has average 2.62 Å.Meanwhile, in the outer vacant octahedral sheet, the distance has average value of 4.25 Å for.It can be said that these contractions from substituted Si atom cause transformation of a planar gibbsite sheet to a material with spherical shape.Until now, there are no reports on the evidence of smallest nano-ball allophane except with diameter of 3.5 to 5.0 nm.However, our calculation result confirmed that the smallest of nano-ball allophane is stable and possible exists in the soil natural environmental.
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