Issue 10, 2018

CdII/ZnII discrimination using 2,5-diphenyl[1,3,4]oxadiazole based fluorescent chemosensors

Abstract

The coordination properties and photochemical response of two fluorescent ligands 2,5-bis{2-[bis(2-pyridylmethyl)aminomethyl]phenyl}[1,3,4]oxadiazole (L1) and 2,5-bis{2-[(1,4,7-triazacyclononane-1-yl)methyl]phenyl}[1,3,4]oxadiazole (L2) towards ZnII and CdII are reported. The ligands contain the 2,5-diphenyl[1,3,4]oxadiazole (PPD) fluorescent probe linked to two coordinating units, namely dipicolylamine (DPA) for L1 and 1,4,7-triazacyclononane (TACN) for L2, through a methylene spacer. Both ligands form mononuclear and dinuclear complexes with these metal ions in aqueous or hydro-alcoholic media. With regard to L1, only the mononuclear CdII complex is highly fluorescent at 368 nm, while the mononuclear ZnII and dinuclear CdII and ZnII complexes are not emissive. Ligand L2 forms an excimer emitting at 474 nm only in the presence of one equivalent of CdII, and potentiometric, spectrophotometric, spectrofluorimetric, and NMR studies and DFT calculations were performed to explain this peculiarity. The discrimination between CdII and ZnII is mainly due to the different coordination environments of the metal ions in the mononuclear complexes; namely CdII is coordinated by both the side arms of each ligand, while ZnII is bound only to one coordinating unit.

Graphical abstract: CdII/ZnII discrimination using 2,5-diphenyl[1,3,4]oxadiazole based fluorescent chemosensors

Supplementary files

Article information

Article type
Paper
Submitted
08 yan 2018
Accepted
09 mar 2018
First published
12 mar 2018

New J. Chem., 2018,42, 7869-7883

CdII/ZnII discrimination using 2,5-diphenyl[1,3,4]oxadiazole based fluorescent chemosensors

M. Formica, G. Ambrosi, V. Fusi, L. Giorgi, M. Arca, A. Garau, A. Pintus and V. Lippolis, New J. Chem., 2018, 42, 7869 DOI: 10.1039/C8NJ00113H

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