Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan, Hunan 411105, People's Republic China.
J Comput Chem. 2010 Aug;31(11):2143-56. doi: 10.1002/jcc.21503.
The chemically switchable actions well imitate the function of a "molecular syringe," has been studied in theory using the 1,3-alternate calix [4]arene bearing a nitrogen-containing crown cap at one side and a bis(ethoxyethoxy) group at another side by the pi-basic calixtube as a pipette and the crown ring as a rubber cap. The model is characterized by geometry optimization using density functional theory (DFT) at B3LYP/6-31G level. The obtained optimized structures are used to perform natural bond orbital (NBO) and frequency analysis. The electron-donating heteroatoms: O and N offer lone pair electrons to the contacting RY* (1-center Rydberg) or LP* (1-center valence antibond lone pair) orbitals of K(+), Ag(+). The results indicate that when the nitrogen atom in the crown ring is protonated, K(+) and Ag(+) will be pushed out to the bis(ethoxyethoxy) side through a pi-basic calixtube. When the nitrogen.H(+) in the crown ring is deprotonated, K(+) and Ag(+) are sucked back to the crown-capped side again. In the course of the coordination, both the intermolecular electrostatic interactions and the cation-pi interactions between the metal ion and pi-orbitals of the two pairs facing inverted benzene rings play a significant role. It is believed that this prototype of a "molecular syringe" is a novel molecular architecture for the action of metal cations.
通过使用一侧带有含氮冠醚的 1,3-交替杯 [4]芳烃和另一侧带有双（乙氧基乙氧基）基团的 π-碱性 calixtube 作为吸管，冠环作为橡胶帽，在理论上研究了化学可切换作用，很好地模拟了“分子注射器”的功能。该模型的特点是使用密度泛函理论（DFT）在 B3LYP/6-31G 水平上进行几何优化。获得的优化结构用于进行自然键轨道（NBO）和频率分析。供电子杂原子：O 和 N 提供孤对电子给接触的 RY*（1 中心 Rydberg）或 LP*（1 中心价反键孤对）轨道的 K(+)、Ag(+)。结果表明，当冠环上的氮原子质子化时，K(+)和 Ag(+)将通过 π-碱性 calixtube 被推到双（乙氧基乙氧基）侧。当冠环上的氮.H(+)脱质子化时，K(+)和 Ag(+)又被吸回到冠封端侧。在配位过程中，金属离子与两对相对倒置苯环的π轨道之间的分子间静电相互作用和阳离子-π相互作用都起着重要作用。相信这种“分子注射器”的原型是一种用于金属阳离子作用的新型分子结构。
