COOPERATIVE BINDING OF 6-(P-TOLUIDINYL)NAPHTHALENE-2-SULFONATE BY BETA-CYCLODEXTRIN DIMERS

A fluorimetric study shows that 6-(p-toluidinyl)naphthalene-2-sulfonat e (TNS-) forms binary complexes with dimeric -bis(6(A)-deoxy-6(A)-beta -cyclodextrin)glutaramide and its succinamide, malonamide, oxalamide, and urea analogues characterized by stability constants 13 010 +/- 20, 16 700 +/- 20, 11 000 +/- 10, 32 640 +/- 90, and 45 230 +/- 70 dm(3) mol(-1), respectively, in aqueous phosphate buffer at pH 7.0, I = 0.10 dm(3) mol(-1) and 298.2 K. These values are substantially greater tha n that for the beta-cyclodextrin . TNS- complex and are indicative of collaborative binding in the beta-cyclodextrin dimer complexes, The fa ctors affecting the stabilities of the cyclodextrin dimer complexes an d their fluorescence characteristics are discussed, and comparisons ar e made with related systems.