Study of the interactions between substituted 2,2 '-bithiophenes and cyclodextrins

The interactions of 4,4'-dimethoxy-2,2'-bithiophene (DMO44BT), 4,4'-dibutox y-2,2'-bithiophene (DBO44BT), and 2,2'-bithiophene (BT) with alpha- and/or beta-cyclodextrins (CD) were investigated by absorption and steady-state fl uorescence spectroscopy. The absorption spectra in all cases are only sligh tly shifted going from water to the CD cavity showing that the ground state conformations of the bithiophenes in the CD cavity remain similar to that found in water. From fluorescence measurements, it was found that DMO44BT a nd DBO44BT form 1:2 (guest:host) complexes with alpha-CD, while DMO44BT and BT form 1:1 complexes with beta-CD. The nature of the interactions involve d in the inclusion complexes are discussed. (C) 1998 Elsevier Science B.V. All rights reserved.