Quencing of perylene fluorescence by Ag+ ions via exciplex formation

✍ Scribed by H. Dreeskamp; A. Laufer; M. Zander

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 344 KB
• Volume: 112
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(84)85573-6

✦ Synopsis

The fluorescence of perylene in alcoholic solution is dynamically quenched by AgC104 resulting in a new emission band with its maximum around 480 nm. Analysis of fluorescence decay curves at various emission wavelen,tis proves the formation of a perylene/Ag+ ion esciples in the quenching reaction.

The fluorescence of perylene and some other compounds in fluid solution is not readily quenched by heavy-atom induced intersystem crossing (ISC) in contrast to that of most other polycyclic aromatic hydrocarbons [ 1 ,z]. This was attributed to the difference in the energy gaps between S1 and the accepting triplet state which is assumed to be T, in the case of perylene and a higher triplet state T,, in most other cases [3,4]. However, quenching of perylene fluorescence is well known to occur via exciplex formation [5,6], e.g. with aromatic amines.

Recently silver (AgNO3) in ethanolic solution of perylene have been shown to decrease the perylene fluorescence quantum yield and moreover significantly change the emission spectrum; no changes in the absorption and excitation spectra were detected [7]. Even more pronounced spectral changes are induced in methanolic solutions by AgClO4_(fig. 1). Following silver salt addition the fluorescence emission spectra appear to resuh from a superposition of the perylene spectrum and a new broad and unstructured .emssion with its maximum around 480 mn.

The perchlorate anion cannot be responsible for these observations since LiClO4 did not induce any changes in flubrescence quantum yield and spectrum_ Ag+ ions on the-other hand have been found to.