New fluorescent pH sensors based on covalently linkable PET rhodamines Aigner, Daniel Borisov, Sergey M. Orriach Fernández, Francisco José Fernández Sánchez, Jorge Fernando Saf, Robert Klimant, Ingo pH sensor Fluorescence Rhodamine Photoinduced electron transfer Covalent dye coupling Click chemistry Financial support from the Austrian Science Fund FWF (Project no. P 21192-N17) and from the Spanish Ministry of Education (Joint Project no. AT2009-0019) is gratefully acknowledged. The authors thank the Institute of Organic Chemistry, Graz University of Technology, particularly Jana Rentner, MSc for kind support in performing LC-MS. Furthermore, we thank Johann Pichler, Institute of Inorganic Chemistry, Graz University of Technology, for acquiring 19F-NMR spectra, as well as Sarah Schiller and Stefan Schobesberger. A new class of rhodamines for the application as indicator dyes in fluorescent pH sensors is presented. Their pH-sensitivity derives from photoinduced electron transfer between non-protonated amino groups and the excited chromophore which results in effective fluorescence quenching at increasing pH. The new indicator class carries a pentafluorophenyl group at the 9-position of the xanthene core where other rhodamines bear 2-carboxyphenyl substituents instead. The pentafluorophenyl group is used for covalent coupling to sensor matrices by “click” reaction with mercapto groups. Photophysical properties are similar to “classical” rhodamines carrying 2′-carboxy groups. pH sensors have been prepared with two different matrix materials, silica gel and poly(2-hydroxyethylmethacrylate). Both sensors show high luminescence brightness (absolute fluorescence quantum yield ΦF≈0.6) and high pH-sensitivity at pH 5–7 which makes them suitable for monitoring biotechnological samples. To underline practical applicability, a dually lifetime referenced sensor containing Cr(III)-doped Al2O3 as reference material is presented. 2020-07-30T07:33:08Z 2020-07-30T07:33:08Z 2012-09-15 info:eu-repo/semantics/article Aigner, D., Borisov, S. M., Fernández, F. J. O., Sánchez, J. F. F., Saf, R., & Klimant, I. (2012). New fluorescent pH sensors based on covalently linkable PET rhodamines. Talanta, 99, 194-201. [http://dx.doi.org/10.1016/j.talanta.2012.05.039] http://hdl.handle.net/10481/63199 10.1016/j.talanta.2012.05.039 eng http://creativecommons.org/licenses/by-nc-nd/3.0/es/ info:eu-repo/semantics/openAccess Atribución-NoComercial-SinDerivadas 3.0 España Elsevier