Interaction Between Cucurbit[8]uril and HCl Salts of 3,4,7,8-Tetramethyl-1,10-phenanthroline

Abstract

To explain ¹H NMR results where two different inclusion orientation isomer complexes of cucurbit[8]urils (Q[8], host) and protonated 3,4,7,8-tetramethyl-1,10-phenanthroline (guest) were observed. The STO-3G and B3LYP/3-21G* calculations were performed on the inclusion complexes of cucurbit[8]urils (Q[8], host) and protonated or free 3,4,7,8-tetramethyl-1,10-phenanthroline (guests). The results of ab initio and DFT energy calculations reveal that the “anti-” orientation was a preponderant alternative structure in 1:2 complexes of Q[8] and the guest, and the inclusion complexes were stabilized by protonation of the guest. The pH influence was investigated which further confirmed these calculation results by electronic absorption spectroscopy.

Keywords:

• Cucurbiturils
• Inclusion complexes
• ¹H NMR
• Quantum chemistry calculations
• UV-vis spectra

Acknowledgements

This work is based on the awards of the International Collaborative Project of the Ministry of Science and Technology (ICPMST, No. 2003DF000030), the Foundation of the Governor of Guizhou Province (FGGP), and the International Collaborative Project of Guizhou Province (ICPGP).