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Ratiometric Fluorescent Nanosensors for Copper(II) Based on Bis(rhodamine)‐Derived PMOs with J‐Type Aggregates
Author(s) -
Qiu Xiaoyong,
Han Shuhua,
Hu Yongfeng,
Sun Baowen
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201406143
Subject(s) - fluorescence , rhodamine , quantum yield , siloxane , moiety , metal ions in aqueous solution , copper , photochemistry , chemistry , rhodamine b , metal , materials science , stereochemistry , polymer , organic chemistry , photocatalysis , catalysis , physics , quantum mechanics
By using pentyl‐linked bis(rhodamine)‐derived tetra‐siloxane (PRh‐Si 4 ) as the organosilica precursor, highly ordered PRh‐bridged periodic mesoporous organosilicas (PRhPMOs) were prepared. When excited at λ =500 nm, the PRhPMO suspension that contained metal ions showed two separate emission peaks at λ =550 and 623 nm. The first peak, located at λ =550 nm, was due to ring‐opening of the spiro structure in the rhodamine moiety and the second, located at λ =623 nm, originated from fluorescent aggregates of the PRh units embedded in the silica framework of the PRhPMO. By using the different intensity ratios of the two fluorescence signals (FI 550/623 ), PRhPMOs could be used as turn‐ON type fluorescent ratiometric chemosensors for Cu 2+ . Furthermore, based on the single‐exciton theory, it was deduced that the fluorescent aggregates formed were of the J‐type and had a coplanar configuration. Consequently, PRhPMOs display a longer fluorescence lifetime and greater fluorescent quantum yield than the respective monomers dissolved in solution, which is consistent with the experimental results.