UV-Vis, fluorescence and NMR spectroscopic investigations on inclusion properties of a designed tetrahomocalix[8]arene with fullerenes C60 and C70 in solution.

Abstract The present article reports the spectroscopic investigations on non-covalent interaction of fullerenes C 60 and C 70 with a macrocyclic receptor molecule, namely, 1,3,5,7-tetrahomo- p - tert -butylcalix[8]arene ( 1 ) in toluene. Jobs method of continuous variation reveals 1:1 stoichiometry for the fullerene complexes of 1 . The most fascinating feature of the present study is that 1 binds selectively C 60 compared to C 70 as obtained from binding constant ( K ) data of C 60 - 1 ( K C60- 1 ) and C 70 - 1 ( K C70- 1 ) complexes which are enumerated to be 265,000 dm 3  mol −1 and 63,430 dm 3  mol −1 , respectively, and selectivity in binding ( K C60- 1 /K C70- 1 ) is estimated to be 4.18 as obtained from UV–Vis study. Steady state fluorescence studies reveal quenching of fluorescence of 1 in presence of fullerenes and the K value of the C 60 - 1 and C 70 - 1 complexes are estimated to be 80,760 and 68,780 dm 3  mol −1 , respectively, with selectivity in binding (K C60- 1 /K C70- 1 ) ∼1.18. 1 H NMR analysis provides very good support in favor of strong binding between C 60 and 1 . The high value of K value for C 60 - 1 complex indicates that 1 forms an inclusion complex with C 60 .