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UV-vis and NMR spectroscopic techniques were employed to demonstrate the ability of the synthetic macrocyclic host cucurbit[7]uril (CB7) to solubilize and stabilize widely used fungicides and anthelmintic drugs of the benzimidazole family in water, namely, albendazole (ABZ), carbendazim (CBZ), thiabendazole (TBZ), fuberidazole (FBZ), and the parent benzimidazole (BZ). CB7 binds the protonated forms of these guests very strongly (e.g., K = 2.6 x [10.sup.7] L/mol for ABZ) but their neutral forms significantly more weakly (e.g., K =6.5 x [10.sup.4] L/mol for ABZ), which reflects a complexation-induced increase of their [pK.sub.a] values by 2.6 units for ABZ, 2.5 units for CBZ, 4.0 units for TBZ, 3.8 units for FBZ, and 3.5 units for BZ. The absolute drug solubilities increased upon complexation from 0.003 to 0.300 mmol/L for ABZ, from 0.160 to 1.12 mmol/L for CBZ, from 0.110 to 1.11 mmol/L for TBZ, and from 0.25 to 0.75 mmol/L for FBZ (for BZ, the solubility enhancement was found to be insignificant). Complexation by CB7 further improves the photostability of the drugs and alters their photophysical properties. Key words: supramolecular chemistry, cucurbit[n]urils, benzimidazole drugs, [pK.sub.a] shifts, solubility enhancement, photostability, drug delivery. On a fait appel aux techniques spectroscopiques d'UV-vis et de RMN pour evaluer l'habilite de l'hote macrocyclique de synthase, cucurbit[7]urile (CB7) a solubilizer et a stabiliser dans l'eau des fongicides et des medicaments antihelmintiques largement utilises, de la famille du benzimidazole, en particulier l'albenzole (ABZ), la carbendazime (CBZ), le thiabendazole (TBZ), le fuberidazole (FBZ) et le produit fondamental, le benzimidazole (BZ). Le CB7 se lie fortement a la forme protonee de ces hotes (par exemple, K = 2,6 x [10.sup.7] L/mol pour l'ABZ), mais les formes neutres sont beaucoup plus faibles (par exemple, K = 6,5 x [10.sup.4] L/mol pour l'ABZ) ce qui est un reflet de l'augmentation induite par la complexation des valeurs de leurs [pK.sub.a] qui est de 2,6 unites pour l'ABZ, de 2,5 unites pour le CBZ, de 4,0 unites pour le TBZ, de 3,8 unites pour le FBZ et de 3,5 unites pour le BZ. Les solubilitees absolues des medicaments augmentent par complexation de 0,003 a 0,300 mmol/L pour l'ABZ, de 0,160 a 1,12 mmol/L pour le CBZ, de 0,110 a 1,11 mmol/L pour le TBZ et de 0,25 a 0,75 mmol/L pour la FBC ; pour le BC, on a trouvee que l'augmentation de solubilite est insignifiante. La complexation des medicaments avec le CB7 augmente de plus la photostabilite des medicaments et elle altere leurs proprieetes photophysiques. Mots-cles: chimie supramoleculaire, cucurbit[n]uriles, medicaments a base de benzimidazole, [pK.sub.a], administration des medicaments. [Traduit par la Redaction], Introduction When guest molecules are noncovalently encapsulated inside water-soluble macrocyclic container compounds such as cyclodextrins, calixarenes, or cucurbiturils, a modification of their chemical and physicochemical properties always occurs owing to [...]

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