Detection of Zn(II) ions by fluorescent pyrene-derived molecular probes

Abstract

Two pyrene-based molecular probes have been synthesised from ortho- and meta-bis(azidodimethyl)benzene and their coordination with Fe(III), Al(III), Fe(II), Zn(II), Ni(II), Cu(II), Cd(II), Hg(II), Ca(II), Mg(II) and Na(I) cations is described. The greatest spectral changes were observed with Zn(II) salts, which are important analytical targets in environmental and biological chemistry, and a detailed investigation on the influence of the counter-ion (F⁻ , Cl⁻ , Br⁻ , I⁻ , , , , and ) was undertaken. Density functional theory studies suggest that Zn(II) is bound in the cleft of the probes in a 1:1 host:guest ratio. A significant hypsochromic shift is observed in the excimer band in the presence of metal salts and is greatest upon the addition of Zn(ClO₄)₂.The limit of Zn(II) detection is in the nanomolar range for the meta-isomer and the binding process is reversible allowing the system to be recycled several times. A protocol is proposed that would allow detection of Zn(II) in aqueous samples.

Keywords::

• zinc
• pyrene
• excimers
• fluorescence sensors
• DFT

Acknowledgements

KJW thanks the organisers of 2013 8-IMSIC (Profs Jeffery Davis, Amar Flood and Lyle Isaacs) held in Arlington for the invitation to write a manuscript for the special edition of Supramolecular Chemistry in honour of this event.

Additional information

Funding

KJW thanks the NSF [OCE-0963064] for funding the ongoing research in the Wallace Laboratory.Supplemental dataSupplemental data for this article can be accessed here: http://dx.doi.org/10.1080/10610278.2013.835050.