Abstract
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 π-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 electrondonating heteroatoms: O and N offer lone pair electrons to the contacting RY* (1-center Rydberg) or LP* (1-center valence antibond lone pair) orbitais 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 π-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-π interactions between the metal ion and π-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.
Original language | English |
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Pages (from-to) | 2143-2156 |
Number of pages | 14 |
Journal | Journal of Computational Chemistry |
Volume | 31 |
Issue number | 11 |
DOIs | |
Publication status | Published - Aug 2010 |
Externally published | Yes |
Keywords
- Calix[4]arene-N-azacrown-5
- Density functional theory (dft)
- Molecular syringe
- Natural bond orbital (nbo)
- Supramolecular chemistry