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Synthesis and Fluorescence Properties of Isatin‐Based Spiro Compounds: Switch off Chemosensing of Copper(II) Ions
Author(s) -
Kundu Ashis,
Pathak Sudipta,
Pramanik Animesh
Publication year - 2013
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201300153
Subject(s) - chemistry , isatin , malononitrile , fluorescence , metal ions in aqueous solution , quinoline , triethylamine , photochemistry , dimethylformamide , solvent , acetone , pyridine , ion , nuclear chemistry , inorganic chemistry , organic chemistry , physics , quantum mechanics , catalysis
A series of isatin‐based spiro compounds 2′,7′‐diamino‐2‐oxo‐1′,4′‐dihydrospiro[indoline‐3,4′‐quinoline]‐3′‐carbonitriles have been synthesized by heating mixtures of isatins, malononitrile, and meta ‐phenylenediamine to reflux in ethanol. Some of the compounds have high fluorescence quantum yields ( Φ F =ca. 0.8) and long fluorescence lifetimes ( τ =ca. 9.0 ns) in the polar solvent acetone. The value of Φ F decreases with increasing polarity of the solvents in the sequence acetone, CH 3 CN, N , N ‐dimethylformamide, and MeOH. All of the compounds fluoresce in a weak basic medium, such as triethylamine, but do not emit in acetic acid. Efficient and selective fluorescence quenching occurs for Cu 2+ ions in solution through complexation, which can be used for detection of Cu 2+ ions in the presence of several other metal ions. Preliminary studies show that these isatin‐based spiro compounds can be used as fluorescence probe for bioimaging of human squamous epithelium and peripheral blood mononuclear (PBM) cells and also for detecting Cu 2+ ions in living cells.