Origin of the high-energy emission of 1,1′-diethyl-2,2′-cyanine dye

✍ Scribed by Christian Königstein; Gottfried Köhler

• Book ID: 103994249
• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 317 KB
• Volume: 84
• Category: Article
• ISSN: 1010-6030
• DOI: 10.1016/1010-6030(94)03867-8

✦ Synopsis

In addition to the yellow emission ascribed to the 3 aggregates of l,l'-diethyl-2,2'-cyanine, this compound also exhibits a high-energy emission around 400 nm in dilute aqueous solutions (c<~D-~ mol 1-l). It was found using time-resolved emission measurements that protonation of l,l'-diethyl-2,2'-cyanine is responsible for this emission. At pH<4, the excited state protolytic reaction competes with ground state protonation. Both pathways give the same excited species, luminescing at 400 nm. The non-protonated form shows only weak fluorescence. The excited state lifetime of the protonated form is 4.5 ns.