Abstract
A new fluorescent molecular receptor 3 based on the cone confirmation of calix[4]arene appended with 2-[4-(N,N-dimethylaminophenyl)iminoethoxy] moieties was synthesised, which exhibits selective fluorescence ‘Turn-On’ response in the presence of only Hg2+ ions among the various metal ions tested with a detection limit up to the nanomolar range. The fluorescence behaviour of receptor 3 in the presence of Hg2+ ions is attributed to the alteration in electronic properties of 3, i.e. working of intramolecular charge transfer (ICT) phenomenon on Hg2+ ions complexation. The nitrogen atoms of the imino moieties got involved in the coordination with mercury ions, which enhances the electron-withdrawing ability of imino nitrogen atoms and, hence, leads to an ICT process consequently resulting in the appearance of an emission band at 444 nm.
Acknowledgements
We are thankful to CSIR (New Delhi) for financial support (Ref. No. CSIR Scheme 01 (2167) 07/EMR-II) and Guru Nanak Dev University for providing research facility.