Long Xia, Meng Ruijie, Wu Weike, Ma Yurong, Yang Dong, Qi Limin
Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry, Peking University (PKU), Beijing 100871 (P.R. China), Fax: (+86) 1062751708.
Chemistry. 2014 Apr 7;20(15):4264-72. doi: 10.1002/chem.201304229. Epub 2014 Mar 18.
Besides studies on the mineralization process, research on the demineralization of minerals provides another way to understand the crystallization mechanism of biominerals and fabricate crystals with complicated morphologies. The formation of ordered arrays of c-axis-oriented calcite microneedles with a tri-symmetric structure and lengths of more than 20 μm was realized on a large scale for the first time through anisotropic dissolution of calcite substrates in undersaturated aqueous solution in the presence of ammonium salts. The lengths and the aspect ratios of the calcite microneedles can be tuned by simply changing the concentrations of the ammonium salts and the dissolution time. The shape of the transverse cross sections of the calcite microneedles obtained in the presence of NH4 Cl and NH4 Ac is almost regularly triangular. The tri-symmetric transverse cross-section geometry of the calcite microneedles could be attributed to the tri-symmetric feature of rhombohedral calcite atomic structures, the synergetic interactions between electrostatic interaction of ammonium ions and dangling surface carbonate groups, and the ion incorporation of halide ions.
除了对矿化过程的研究外，对矿物脱矿作用的研究为理解生物矿物的结晶机制和制备具有复杂形态的晶体提供了另一种途径。通过在铵盐存在下，方解石基底在不饱和水溶液中的各向异性溶解，首次大规模实现了具有三对称结构且长度超过20μm的c轴取向方解石微针有序阵列的形成。通过简单地改变铵盐浓度和溶解时间，可以对方解石微针的长度和纵横比进行调节。在氯化铵和醋酸铵存在下获得的方解石微针的横向横截面形状几乎呈规则三角形。方解石微针的三对称横向横截面几何形状可归因于菱面体方解石原子结构的三对称特征、铵离子与表面悬空碳酸根离子静电相互作用之间的协同作用以及卤离子的离子掺入。
