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


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 forms monuclear and dinuclear complexes with these metal ions in aqueous or hydro-alcoholic media. With regard to L1, only mononuclear CdII complex is highly fluorescent at 368 nm, while 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, NMR studies and DFT calculation were performed to explain this peculiarity. The discrimination between CdII and ZnII is mainly due to the different coordination environment of the metal ions in the mononuclear complexes, namely the CdII is coordinated by both the side arms of each ligand while ZnII is bound only to one coordinating unit.

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Publication details

The article was received on 08 Jan 2018, accepted on 09 Mar 2018 and first published on 12 Mar 2018

Article type: Paper
DOI: 10.1039/C8NJ00113H
Citation: New J. Chem., 2018, Accepted Manuscript
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    CdII/ZnII discrimination by 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, Accepted Manuscript , DOI: 10.1039/C8NJ00113H

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