Institute of Functional Interfaces, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Sci Rep. 2012;2:921. doi: 10.1038/srep00921. Epub 2012 Dec 4.
A novel class of metal organic frameworks (MOFs) has been synthesized from Cu-acetate and dicarboxylic acids using liquid phase epitaxy. The SURMOF-2 isoreticular series exhibits P4 symmetry, for the longest linker a channel-size of 3 × 3 nm(2) is obtained, one of the largest values reported for any MOF so far. High quality, ab-initio electronic structure calculations confirm the stability of a regular packing of (Cu(++))(2)- carboxylate paddle-wheel planes with P4 symmetry and reveal, that the SURMOF-2 structures are in fact metastable, with a fairly large activation barrier for the transition to the bulk MOF-2 structures exhibiting a lower, twofold (P2 or C2) symmetry. The theoretical calculations also allow identifying the mechanism for the low-temperature epitaxial growth process and to explain, why a synthesis of this highly interesting, new class of high-symmetry, metastable MOFs is not possible using the conventional solvothermal process.
一种新型的金属有机骨架（MOFs）已经通过液相外延法由醋酸铜和二羧酸合成。SURMOF-2 同晶系列具有 P4 对称性，对于最长的连接体，得到了 3×3nm(2)的通道尺寸，这是迄今为止报道的任何 MOF 中最大的通道尺寸之一。高质量的从头算电子结构计算证实了具有 P4 对称性的（Cu(++))(2)- 羧酸盐桨轮平面的规则堆积的稳定性，并表明 SURMOF-2 结构实际上是亚稳的，向具有较低的两倍（P2 或 C2）对称性的体 MOF-2 结构的转变具有相当大的活化能垒。理论计算还可以确定低温外延生长过程的机制，并解释为什么使用传统的溶剂热法不可能合成这种具有高对称性、亚稳性的新型 MOFs。
