Kua Jeremy, Gyselbrecht Charles R
Department of Chemistry and Biochemistry, University of San Diego, 5998 Alcala Park, San Diego, California 92110, USA.
J Phys Chem A. 2008 Sep 25;112(38):9128-33. doi: 10.1021/jp8047983. Epub 2008 Aug 28.
Heterotrimeric arylboroxines can be favorably formed by designing one of the arylboronic acid monomers to contain a pendant Lewis base. Using density functional theory (B3LYP//6-311+G*) calculations including Poisson-Boltzmann implicit solvent, we found that AB2 trimeric arylboroxines were thermodynamically favored over A2B, A3, or B3, where A and B are monomeric arylboronic acids with and without a pendant Lewis base, respectively. The most stable AB2 trimers were formed when the B monomer contained electron-withdrawing substituents, particularly halogens in the para-position or pi-acceptors in the meta-position. On the other hand, adding different para-substituents to the A monomer did not significantly change the energetics. Our calculations also suggest that ABC trimers with three different monomers will not be significantly favored over AB2 trimers when making small electronic perturbations, by changing the substituents on each monomer.
通过设计其中一种芳基硼酸单体使其含有一个侧链路易斯碱，可以顺利地形成异三聚体芳基硼酸酯。使用包括泊松-玻尔兹曼隐式溶剂的密度泛函理论（B3LYP//6-311+G*）计算，我们发现AB₂三聚体芳基硼酸酯在热力学上比A₂B、A₃或B₃更有利，其中A和B分别是带有和不带有侧链路易斯碱的单体芳基硼酸。当B单体含有吸电子取代基时，尤其是对位的卤素或间位的π-受体时，会形成最稳定的AB₂三聚体。另一方面，在A单体上添加不同的对位取代基不会显著改变能量学。我们的计算还表明，当通过改变每个单体上的取代基进行小的电子扰动时，具有三种不同单体的ABC三聚体不会比AB₂三聚体更受青睐。
