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Versatile Para‐Substituted Pyridine Lanthanide Coordination Complexes Allow Late Stage Tailoring of Complex Function
Author(s) -
Starck Matthieu,
Fradgley Jack D.,
De Rosa Davide F.,
Batsanov Andrei S.,
Papa Maria,
Taylor Michael J.,
Lovett Janet E.,
Lutter Jacob C.,
Allen Matthew J.,
Parker David
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202103243
Subject(s) - chemistry , pyridine , electron paramagnetic resonance , lanthanide , substituent , cationic polymerization , ligand (biochemistry) , photochemistry , crystallography , medicinal chemistry , polymer chemistry , ion , organic chemistry , nuclear magnetic resonance , biochemistry , physics , receptor
Abstract A series of cationic and neutral p −Br and p −NO 2 pyridine substituted Eu(III) and Gd(III) coordination complexes serve as versatile synthetic intermediates. Nucleophilic aromatic substitution occurs readily at the para position under mild conditions, allowing C−N and C−C bond forming reactions to take place, permitting the introduction of azide, amino and alkynyl substituents. For Eu(III) complexes, this approach allows late stage tuning of absorption and emission spectral properties, exemplified by the lowering of the energy of an LMCT transition accompanied by a reduction in the Eu−N py bond length. Additionally, these complexes provide direct access to the corresponding Eu(II) analogues. With the Gd(III) series, the nature of the p ‐substituent does not significantly change the EPR properties (linewidth, relaxation times), as required for their development as EPR spin probes that can be readily conjugated to biomolecules under mild conditions.