Binding studies of cucurbit[7]uril with gold nanoparticles bearing different surface functionalities
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Section snippets
Result and discussion
We have designed a series of nanoparticles with benzylammonium terminal group possessing different functionalities at the para position of the benzene ring, which is the least sterically hindered position for binding process based on the reported crystal structures of cucurbiturils.50, 51 Seven quaternary amine (DMBA) and five tertiary amine (MMBA) derivatives (Fig. 1) were synthesized to represent a wide range of functionalities that bring at least one of the following attributes to the
Conclusion
We have used isothermal titration calorimetry to monitor the binding interactions of CB[7] with twelve different AuNPs. Binding studies revealed that NP1–NP7 possessing DMBA head groups showed a higher binding affinity toward CB[7] compared to NP8–NP12 having MMBA head groups. Insertion of the tBu group at the para position of the benzene ring led to a lower binding due to the steric effect. Although not very strong difference in Ka constants was observed between electron donating and
Acknowledgements
This work was supported by the NIH (NIH R01 EB014277). T.M. is grateful to the Japan Society for the Promotion of Sciences (JSPS) for a Postdoctoral Fellowship for Research Abroad and for the Strategic Young Researcher Overseas Visits Program for Accelerating Brain Circulation.
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