2013
DOI: 10.1002/ejoc.201201655
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Cucurbit[7]uril Host–Guest Complexes with Biguanidinium Cations in Aqueous Solution

Abstract: The host–guest complexations of a series of biguanidinium cations (metformin and phenformin) and bis(biguanidinium) dications (chlorhexidine and alexidine) by the host molecule cucurbit[7]uril (CB[7]) in aqueous solution have been investigated by 1H NMR spectroscopy and ESI mass spectrometry. Metformin forms both 1:2 and 1:1 host–guest complexes, whereas phenformin forms only a 1:1 complex. The two bis(biguanidinium) dications both form sequential 1:1, 2:1 and 3:1 host–guest complexes, however, the mechanism i… Show more

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Cited by 13 publications
(3 citation statements)
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“…Binding to CB[7] occurs over the benzyl moiety which stabilizes the N 3 N 1 tautomer of the diprotonated from, raising the p K a1 value to 6.41 and the p K a2 value to 10.72. We have observed a negative (albeit small) p K a shift with the CB[7] binding of the diabetic drug metformin ( 23 ) . With the diprotonated form of this small biguanide molecule, the positive charges are close together and cannot independently bind to the two portals of CB[7], weakening the binding compared to the monoprotonated conjugate base.…”
Section: Ground State Acid‐base Equilibriamentioning
confidence: 99%
“…Binding to CB[7] occurs over the benzyl moiety which stabilizes the N 3 N 1 tautomer of the diprotonated from, raising the p K a1 value to 6.41 and the p K a2 value to 10.72. We have observed a negative (albeit small) p K a shift with the CB[7] binding of the diabetic drug metformin ( 23 ) . With the diprotonated form of this small biguanide molecule, the positive charges are close together and cannot independently bind to the two portals of CB[7], weakening the binding compared to the monoprotonated conjugate base.…”
Section: Ground State Acid‐base Equilibriamentioning
confidence: 99%
“…4B, rows 2-4). Additionally, a panel of internal standards with known solution-phase affinities for CB [7] (with a range of binding constants; K a = 5 Â 10 5 -5 Â 10 12 M À1 ) [38][39][40][41] was run in order to ensure that the solid-phase data were consistent with the known solution binding (Fig. 4B, graph 1B-1F).…”
mentioning
confidence: 99%
“…For instance, the biguanide functional group is found in drug molecules used to treat hypoglycemia and type 2 diabetes. MacGillivray and Macartney [64] studied the host-guest complexation of metformin, phenformin, chlorhexidine, and alexidine with CB [7] employing ESI-MS. The species observed in the ESI-MS spectra corresponded to 1:2 and 1:1 hostguest complexes for biguanidinium cation metformin, only 1:1 for biguanidinium cation phenformin and 1:1, 2:1 and 3:1 for both dications (chlorhexidine and alexidine).…”
Section: The Combination Of Hydrophobic and Dipole Interactions In Th...mentioning
confidence: 99%