Mukkamala Saratchandra Babu, Anson Christopher E, Powell Annie K
Institut für Anorganische Chemie der Universität Karlsruhe, Engesserstrasse 15, D76131 Karlsruhe, Germany.
J Inorg Biochem. 2006 May;100(5-6):1128-38. doi: 10.1016/j.jinorgbio.2006.02.012. Epub 2006 Feb 28.
The structure-directing influence of the organic dicarboxylates malonate, succinate, glutarate and adipate as templating species on the hydrothermal formation of CaCO(3) was investigated at different temperatures (60, 80, 90, 120, 150 and 190 degrees C) and with a range of molar ratios of [Ca(2+)]/[templating species] (20, 14.3, 10, 7.7, 5, 1, 0.5 and 0.33). In the presence of the dicarboxylates, one, two or three polymorphs of CaCO(3) - calcite, aragonite and vaterite - could be formed, depending on the reaction conditions. In addition changes in crystal morphology were observed for the CaCO(3) polymorphs depending on the concentration of the template. In contrast, synthesis under ambient conditions of temperature and pressure resulted only in calcite formation, although template-dependent morphological changes were again observed. Crystalline products were all characterized by powder X-ray patterns and SEM (Scanning Electron Microscopy) micrographs. The ambient reactions with the chelating, dinucleating carboxylato ligands H(3)heidi and H(5)hpdta produce more profound changes in calcite morphology. With H(3)heidi rounded calcite crystals with shapes similar to that of otoliths are formed and with H(5)hpdta the formation of microtrumpets of constructed from bundles of nanocrystals of calcite is observed. The possible mode of action of these ligands on calcite formation is discussed in the context of known coordination chemistry with other metal ions.
研究了丙二酸、琥珀酸、戊二酸和己二酸等有机二羧酸盐作为模板剂对碳酸钙水热形成的结构导向影响，实验在不同温度（60、80、90、120、150和190℃）下进行，并采用了一系列[Ca(2+)]/[模板剂]的摩尔比（20、14.3、10、7.7、5、1、0.5和0.33）。在二羧酸盐存在的情况下，根据反应条件，碳酸钙的一种、两种或三种多晶型物——方解石、文石和球霰石——都可能形成。此外，观察到碳酸钙多晶型物的晶体形态会因模板剂浓度而发生变化。相比之下，在常温常压条件下合成仅生成方解石，尽管再次观察到了依赖模板剂的形态变化。结晶产物均通过粉末X射线衍射图谱和扫描电子显微镜（SEM）照片进行表征。与螯合的双齿羧基配体H(3)heidi和H(5)hpdta的常温反应对方解石形态产生了更显著的变化。使用H(3)heidi会形成形状类似于耳石的圆形方解石晶体，而使用H(5)hpdta则观察到由方解石纳米晶体束构成的微喇叭的形成。在与其他金属离子的已知配位化学背景下，讨论了这些配体对方解石形成的可能作用方式。
