Title
Luminescent Eu3+ complexes in acetonitrile solution: anion sensing and effect of water on the speciation
Author
Fabio Piccinelli, Marco Leonzio, Marco Bettinelli, Andrea Melchior, Georgina Faura, Marilena Tolazzi
Year
2016
Journal
Inorganica Chimica Acta
Abstract
In this paper the trifluoromethansulphonate (CF3SO3-, OTf-, triflate) Eu3+ complexes of a new family of imine-based ligands with 1:1 ligand to metal mole ratio have been employed for luminescence sensing of NO3-, F-, Cl-, Br-, I-, CH3COO- and ClO4-, in non-anhydrous acetonitrile (wet AN = wAN) solution. The ligands show different donor ability and stereochemistry. In particular, they consist of the trans racemic isomers containing pyridine or furan as donating ring [N,N’-bis(2-pyridylmethylidene)- 1,2-(R,R+S,S)-cyclohexanediamine, L1; N,N’-bis(2-furanylmethylidene)- 1,2-(R,R+S,S)-cyclohexanediamine, L2 and the cis (meso) isomer containing the pyridine ring N,N’-bis(2-pyridylmethylidene)- 1,2-(R,S)-cyclohexanediamine, L3]. As far as the sensitivity and the selectivity towards the different anions are concerned, the donor ability of the heteroaromatic ring within the ligand backbone, plays a crucial role: the poorly donating furan-based ligand L2 shows the best sensitivity and selectivity towards nitrate. On the other hand, the stereochemistry of the pyridine-based ligand shows a significant effect on the bromide sensing. The effects of the water content on the stability of these complexes have been also studied. Even though the speciation in non-anhydrous is the same as in anhydrous AN (1:1 EuL and 1:2 EuL2 species), their stability is significantly lower. The reasons for this behavior are proposed to be mainly found in the different solvation of both Eu3+ ion and the ligands.
Instrument
FP-8200
Keywords
Fluorescence, Ligand binding, Inorganic chemistry, Materials