Excimer formation in inclusion complexes of antihypertensive drugs with HP-α- and HP-β-cyclodextrins

The inclusion complexation behavior of three antihypertensive drugs, viz., salbutamol, sotalol and atenolol with hydroxypropyl-α-cyclodextrin (HP-α-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) is investigated by UV-visible, steady state/time resolved fluorescence and PM3 methods and compared with complexation with α-CD and β-CD. In the presence of any of the CDs, dual emission is observed in these drugs, whereas in the absence of CDs, single emission is seen. Addition of CD to aqueous solutions of the drugs results in excimer emission. In CD solutions, the monomer emission intensity decreases regularly while excimer emission intensity increases. The excimer emission is concluded to be due to a 1:2 inclusion complex between the CD and the drugs.