Spectroscopic Study the Interaction of Cucurbit[n]urils with 1-Naphthol,2-Naphthol

Interaction of cucurbit[n]urils with two naphthol isomers and the influence of pH on the interaction were studied by using UV-Vis spectroscopy and fluorescence spectrophotometry.The experimental results revealed that cucurbit[8]urils always forms a 1∶1 complex with the naphthol isomers.However,UV-Vis spectroscopy and fluorescence spectrophotometry method showed no obvious interaction of cucurbit[6]urils and cucurbit[7]urils with naphthol isomers in all pH values.Formation constant of Kf was found to be 4.2×104 L·mol-1,1.6×104 L·mol-1 of 1-naphthol and 2-naphthol with cucurbit[8]urils respectively by using fluorescence spectrophotometry.Formation constant of Kf was found to be 4.2×104 L·mol-1,5.4×104 L·mol-1 of 1-naphthol and 2-naphthol with cucurbit[8]urils respectively by using UV-Vis spectroscopy.There is no interaction between cucurbit[8]urils and the naphthol isomers in strong alkalescent medium.The cucurbit[8]urils could include the guest with a 1∶1 ratio in acid and neutral medium.