Key words
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lanthanide; tripod; thermodynamics; kinetics; luminescence; sensor; analytical; paramagnetic
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Research programs
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COST-Action D38 - Meta-based Systems for Molecular Imaging Applications
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Short description
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This project is focused on development of new analytical sensors based on modulation of luminescence or relaxivity of Ln(III) complexes. In order to obtain thermodynamically and kinetically stable compounds, we have designed several tripodal ligands to bind Ln(III) in the seven- or eight-coordinate cavities, which leaves one or two free positions for interacting with an anionic analyte. In addition, these metal-based systems with exchanging water molecules may potentially result in new paramagnetic probes for magnetic resonance imaging. The particular interest is devoted to the development of dual (luminescent and paramagnetic) probes for imaging biological events. First, we will target monometallic complexes with neutral ligands, but our work will be further extended for water-soluble ligands containing carboxylic groups. We plan to investigate thermodynamic, kinetic and photophysical properties of these complexes, which (i) brings a better insight into their stabilities required for future applications in vivo (low toxicity), and (ii) allows to make predictions for new, moe efficient compounds. Consequently, the detailed studies of interactions between selected Ln(III) complexes and analytes such as fluoride, carboxylic acids, aminoacids and other biologically interesting anions will be undertaken. Related analytical procedures based on the luminescent and paramagnetic responses Ln(III) complexes will be worked out.
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Further information
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Full name of research-institution/enterprise: Université de Genève Département de Chimie Minérale, Analytique et Appliquée
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Partners and International Organizations
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BE, CH, CY, CZ, DE, ES, FI, FR, GR, HU, IT, NL, PL, PT, TR, UK
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Abstract
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The thermodynamic studies with the symmetrical ether-bridged ligand L1 have been enriched with calorimetry studies in order to gain information about enthalpy and entropy changes during complexation processes. The stability constants closely reflect the values fitted from spectrophotometric titrations. The obtained data will be published soon. The synthesis of an analogous amine-bridged ligand L2 has been performed and optimised. To avoid the formation of polysubstituted amines, an alternative strategy using a transition metal template (Ni, Pb) was elaborated. The preparation and characterisation of mononuclear complexes of L2 with lanthanides are currently under progress. Simultaneously, synthetic pathways for the preparation of unsymmetrical ligands bearing ether- or amine-bridged platforms have been investigated. The proposed reaction scheme leads to octadentate ligands with terminal carboxamide or carboxylate functions. Moreover, a new presumably water-soluble tripodal ligand with pending hydroxy groups is under study. These investigations will be further pursued beyond this project.
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References in databases
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Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. +41 31 322 74 82 Swiss Project-Number: C07.0078
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