Evaluation of the chemo- and shape-selective association of a bowl-type dodecavanadate cage with an electron-rich group

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 48; no. 21; pp. 7138 - 7143
• Main Authors: Kikukawa, Yuji, Kitajima, Hiromasa, Hayashi, Yoshihito
• Format: Journal Article
• Language: English
• Published: England 07.06.2019
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c9dt00462a

The host-guest interaction between a half spherical-type dodecavanadate ( V12 ) and a neutral molecule guest was evaluated by monitoring the flip of a VO 5 unit caused by the presence or absence of a guest in the cavity of V12 . In N , N -dimethylformamide (DMF), V12 adopted the guest-free form ( V12-free ). By the addition of several guest molecules, such as acetonitrile, nitromethane, and dichloromethane, the structural conversion to the guest-inserted form ( V12(guest) ) was observed with the affinity constants of 137 ± 10 M −1 , 0.14 ± 0.1 M −1 , and 0.15 ± 0.1 M −1 , respectively. In the case of 1,2-dichloroethane, 1,2-dibromoethane, and 1,2-diiodoethane, the constants were 35 ± 5 M −1 , 114 ± 5 M −1 , and 2.1 ± 0.5 M −1 , respectively, suggesting that the bromo group is the best fit to the cavity of the bowl. A cyclic carbonate, 5- and 6-membered lactones, cyclobutanone, and hexanal were inserted into the V12 host, while a non-cyclic carbonate, non-cyclic and 7-membered cyclic ester, a ketone with a 5-membered ring, and benzaldehyde showed no effect on the guest insertion. The V12 host preferred to hold a guest with an electron-rich group, and the bowl-type structure showed the unique shape-selective interaction with the guest. The affinity between a guest molecule and a dodecavanadate host molecule was evaluated via monitoring the structural transformation caused by the presence of a guest molecule.