Photophysical properties of rhodamine isomers: A two-photon excited fluorescent sensor for trivalent chromium cation (Cr 3+)

• Published in: Analytica chimica acta Vol. 665; no. 2; pp. 215 - 220
• Main Authors: Wan, Yan, Guo, Qianjin, Wang, Xuefei, Xia, Andong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 30.04.2010; Elsevier
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Fluorescence on/off; Fluorescent sensor; General, instrumentation; Rhodamine; Spectrometric and optical methods; Trivalent chromium ion (Cr 3+); Two-photon excitation; Rhodamine; Fluorescent sensor; Trivalent chromium ion (Cr 3+); Fluorescence on/off; Two-photon excitation; Fold; Förster resonance energy transfer; Fluorescence; Selectivity; Metal; Fluorescence spectrometry; Isomer; Chromium ion; Absorption; Detection limit; Trivalent cation; ); Trivalent chromium ion (Cr; Concentration; Chemical sensor; Wavelength; Sensitivity; Chromium; Detection; Application; Conformation
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2010.03.035

We introduce a new rhodamine-based fluorescent chemosensor, FD8 which exhibits a distinct two-photon excited fluorescence (TPEF) on/off characteristic upon binding Cr 3+ ions. By coordination with metal cation, conformation of FD8 changes from spirocyclic to open-ring, resulting in remarkable enhancement of absorption and fluorescence both in one- and two-photon excitations. As a result, a 29-fold enhancement of two-photon excited fluorescent intensity was observed when 10 eq. Cr 3+ was added to the FD8 solution. The detection limit of Cr 3+ cation concentration down to 1 μM (0.01 eq. of FD8) was achieved under our experimental condition. Besides the excitation within ultraviolet regime by fluorescence resonance energy transfer (FRET) mechanism, the TPEF on/off behavior further extends the excitation to near infrared regime (the biological optimal window of 700–1200 nm), and shows more effective sensitivity. The broad excitation wavelength, on/off fluorescence and high selectivity to Cr 3+ enable FD8 to be a powerful Cr 3+ cation sensor with potential application, especially in biological detection. To the best of our knowledge, this is the first report about two-photon fluorescent sensor for Cr 3+ ions.