| Supramolecular chemistry is one of the chemistry that investigated noncovalent interaction between molecules. Cucurbit[n]uril (CB[n], n=5-8,10), a cyclic host molecules comprising of n glycoluril units bridged by2n methylene groups, possesses a hydrophobic inner cavity and two restrictive portals lined with ureido carbonyl groups. It is well known in the formation of host-guest complexes with a range of guests. CB[n]s have been exploited in material science, catalytic science, life science, environmental chemistry, and many others areas. In this paper, a series of guests were designed and synthesized. The interaction of these guests with CB[n](n=7,8) was studied as follows:1. The interaction of systems containing cucurbit[8]uril and [CmMV]2+(m=4,5,7,12) with1,4-dihydroxybenzene (HB), or2,6-dihydroxynaphthalene (HN) was investigated by1H NMR, NOES Y, ESI-MS, UV-vis spectra and optimized molecular modeling study. The experiment results revealed the different locations of the long alkyl chain in the1:1:1CT complexes formed among CB[8],[CmMV]2+(m=4,5,7,12) and HB(HN) in water solution. In the case of1:1:1inclusion complex of [CmMV]2+-CB[8]-HB (m≥5), the long alkyl chain were located inside the hydrophobic cavity of CB[8]. When m≤4, the1:1:1inclusion complex of [CmMV]2+-CB[8]-HB was formed with alkyl chain located outside the host cavity. After addition of HN to the solution of [C12MV]2+-CB[8]-HB, HN could form a more stable CT complex with viologen unit inside the CB[8] cavity to kick HB and the alkyl chain out of the cavity of CB[8]. The results will be a significant addition to the understanding of cucurbituril binding of guests for supramolecular chemists. The discovery might be also very useful for providing an opportunity to design more advanced molecular machines or supramolecular switches based on folding/unfolding motion.2. A novel highly sensitive and selective fluorescent sensor PMV for Zn2+in pure water has been developed. Moreover, PMV shows a obvious "Switch-Off’ state after supramolecular nanocapsule fomation upon CB[8] was added to the system. Whereas, a bright "Switch-On" state was observed with the rupture of the capsule when1-amantadine hydrochloride was added following. Furthermore, The possible ICT mechanism of the fluorescence enhancement and quenching was investigate by studying the inclusion complexes of PMV-Zn2+with CB[7] and CB[8].3. Complex1can form stable1:1or1:2inclusion complexes with CB[7]in aqueous solution. Whereas it can only form a1:1inclusion complex with CB[8]. Moreover, Complex1taking a U-shaped conformation inside the cavity of CB[8] with Ru complex as a blocker in inclusion complex with CB[8]. In the presence of the sacrificial electron donor TEOA, the photoinduced stable MV+· dimer inside one CB[8] cavity was formed. This process could be used to create a novel light driven molecular "lock", which can be "unlock" by molecular oxygen. The light driven molecular "lock" and "unlock" processes can be repeated for several times with good reversibility. We believe that this system may provide some fundamental understanding for further design and synthesis of potential light-driven molecular devices and machines.4. A series of Ru(dpy)3derivatives complex3were designed and synthesized. The supramolecular self-assembly of complex3with CB[n](n=7,8) in aqueous solution was investigated by using1H NMR,2D NMR, and ESI-MS spectra. The experimental results revealed that complex3a,3b can interact with CB[7] or CB[8] to form1:1inclusion complexes. It was found that the cavity size and the length of alkyl chain played an important role in the formation of the bonding modes. The photochemistry properties of inclusion complex of3b with CB[8] were studied by using NMR, Uv-vis spectra and electrochemistry. The photoinduced MV+· radical could be stabilized upon addition of CB[8] in the presence of the sacrificial electron donor TEOA. |
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