Elucidation of multiple-point interactions of pyranine fluoroprobe during the gelation

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 72; no. 2; pp. 332 - 338
• Main Authors: Yilmaz, Yasar, Uysal, Nihan, Gelir, Ali, Guney, Orhan, Aktas, Demet K., Gogebakan, Savas, Oner, Aylin
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01-03-2009
• Subjects: Acrylamide - chemistry; Arylsulfonates - chemistry; Electrostatic interaction; Fluorescent Dyes - chemistry; Fluoroprobe; Gels - chemistry; Intragel complexation; Molecular Structure; Phase Transition; Polymerization; Spectral shift; Spectral shift; Polymerization; Intragel complexation; Fluoroprobe; Electrostatic interaction
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2008.09.012

We have studied the multiple-point interactions of the pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt; 3sPyOH) fluoroprobe with polymer chains during the free-radical polymerization of acrylamide (AAm) by using the steady state fluorescence measurements. We observed a considerable blue shift from 515
nm to 406
nm in the emission spectra due to a C–O ether bond formation between the hydroxylic oxygen of 3sPyOH and a terminal C-atom of the growing AAm chain. Furthermore ionic (electrostatic) interactions occur between the three ionized sulfonic acid groups (
SO
3
−) of 3sPyOH and protonated amide groups on the AAm chains. These electrostatic interactions also cause a gradual red shift in the maximum of the short-wavelength-peak, from 406
nm to 430
nm. The results showed that the pyranine can be used as a probe for real time monitoring of the polymerization process of AAm system since it monitors both the progression of the polymerization via chemical binding over OH group and the change in the local density of the polymerizing sample by means of the gradual red shift in the short-wavelength-peak via ionic interactions over
SO
3
− groups.