开发具有高活性和选择性的氧还原反应(ORR)电催化剂对于提升下一代能源技术的性能至关重要,这取决于催化还原分子氧的效率。在细胞色素c氧化酶(C c Os)的结构中,与Fe轴向位置结合的组氨酸咪唑残基在促进O 2选择性还原为水方面起着至关重要的作用。受大自然的启发,我们在此报告了与咪唑配体连接的 Co III corrole 1的合成及其电催化 ORR 和 O 2结合特征。与不含咪唑类似物相比,配合物1在 0.1 mol/L KOH 溶液中,与可逆氢电极 (RHE) 相比,半波电位E 1/2 = 0.82 V 的选择性四电子/四质子 (4e - /4H + ) ORR 的活性显着增强。重要的是,我们证明了束缚的轴向咪唑配体在热力学和动力学上提高了1的O 2结合能力,这对于提高电催化ORR性能至关重要。这项工作提出了一个例子,通过引入轴向咪唑配体来增强 O 2结合和活化,从而提高 Co 咔咯的电催化
Polymorphic Diversity: <i>N</i>-Phenylbenzamide as a Possible Polymorphophore
作者:Caitlin F. Zipp、Heini W. Dirr、Manuel A. Fernandes、Helder M. Marques、Joseph P. Michael
DOI:10.1021/cg400356s
日期:2013.8.7
In this work, we identify and describe a moiety that may be capable of encouraging the formation of polymorphs. Four new N-phenylbenzamide-based compounds have been synthesized yielding four pairs of polymorphs upon recrystallization. The structures of these have been discussed and compared with the previously reported polymorphs of N[2-(hydroxymethyl)phenyl]benzamide. The results indicate that the conformation of the N-phenylbenzamide group is generally constant but is sometimes altered by the crystal packing. The N-phenylbenzamide group is capable of intermolecular N-H center dot center dot center dot O hydrogen bonding but requires a change in conformation which is generally resisted by the molecule. As a consequence, weak forces such as C-H center dot center dot center dot O, C-H center dot center dot center dot N, C-H center dot center dot center dot pi, and pi center dot center dot center dot pi interactions play significant but varying roles in these structures. One possible reason for the varying nature of the pi center dot center dot center dot pi interactions may be due to the variation of the electrostatic potential across the N-phenylbenzamide group in which negative and positive regions alternate across the face of the molecule. It is the combination of all these attributes that possibly leads to polymorphism being observed in the structures reported here.