On the Mechanism of the Fluorescence Reaction System of Salicylfluorone-Surfactant-Hydroxypropyl-β-cyclodextrin

The mechanism of the fluorescence reaction system of salicylfluorone(SAF)-surfactant(SF)-hydroxypropyl-β-cyclodextrin (HP-β-CD) was studied. As shown by the experimental results: the fluorescence intensity of SAF was enhanced to different extents by the addition of SF, and most significant enhancement of intensity was given by non-ionic SF′s, such as Triton X-100, and OP; the cause for this effect was deduced as the formation of hydrogen bond between ethoxy groups of SF and hydroxy groups of SAF; the fluorescence intensity of SAF was enhanced to a greater extent by simultaneous addition of SF and HP-β-CD, and similarly greater extent of enhancement was caused by non-ionic SF′s; it was deduced that besides the formation of hydrogen bond as described above, the increase of fluorescence intensity was caused by the increase of hydrophilicity of SAF due to its ortho-OH groups leading to the wrapping and complexing of phenyl group of SAF by entering into the cavity of HP-β-CD molecule, and restricting the alkyl chain of SF from entering into the cavity, thus leading to increase of rigidity and raise of rate of production of fluorescence quanta.