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P1

Fluorescence Dynamics of Coumarin Molecule in Supramolecular Confinements: from Cyclodextrin, through Double in Micelle, to Thiolated Dimer


Fluorescence dynamics of coumarin molecule in supramolecular complexes based on cyclodextrin and thiolated cyclodextrin is determined. The supramolecular confinement of coumarin, C522, in cyclodextrin, CD, cavity with additional placement of this complex into the reverse sodium dioctyl sulfosuccinate, AOT, micelle as the double confinement is compared. The ultrafast decay in the case of w=3 ranges from 9.5 to 16 ps, with an average of 12.6 ps, in the case of the C522/micelle system and from 9.0 to 14.5 ps, with an average of 11.8 ps, in the case of the C522/CD/micelle system. Increasing the w values (from 10 to 40) result in a decrease of the ultrafast decay values in both cases to an average value of about 6.5 ps. The average ultrafast decay times are 12.6 ps and 6.5 ps for the micelle sizes of w = 3 and w = 40, respectively. These results clearly demonstrate the effect of the micelle and this study can shed some light on solvation of the complex system as a potential model for biology. The solvation and confinement of coumarin C153 within supramolecular host/guest complexes based on ß-cyclodextrin (ß-CD) and 6-deoxy-6-thio-ß-cyclodextrin (ß-CD-SH) in water are studied by fluorescence spectroscopy. For ß-CD/C153, the 1:1 complex is proposed, and for ß-CD-SH/C153 both the 1:1 and 2:1 complexes are believed to be formed. The 2:1 ß-CD-SH/C153 complex has an association constant of 4.2×105?M-1 and a C153 population of 82?%, which are interestingly high values, indicating that the proposed ß-CD-SH dimers structure are connected by covalent disulfide bonds; this is supported by mass spectrometry. Solvation related to fast hydrogen-bond rearrangement as a part of fluorescence relaxation is determined by the ultrafast components of time-resolved spectroscopy to be 3 and 7 ps for the 1:1 ß-CD/C153 and 2:1 ß-CD-SH/C153 complexes, respectively.

  1. Eduard Jane, Vojtech Szoecs, Olga Grancicova, Tibor Palszegi, Michal Zitnan, Ignac Bugar, Dusan Lorenc, Dusan Velic: Fluorescence Dynamics of Coumarin C522 as a Function of Micelle Confinement along with Cyclodextrin Supramolecular Complex Formation, ChemPhysChem. - 13, (2012), 4207-4217
  2. Marianna Gregova Trencanova, Vojtech Szoecs, Sona Halaszova, Monika Jerigova, Ludovit Haizer, Eduard Jane, Dusan Velic: Fluorescence Dynamics of Monocyclodextrin- and Bis(thiol-cyclodextrin)-Coumarin C153 Complexes, ChemPhysChem. - Vol. 16, No. 11 (2015), 2466 2473