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Lanthanide(III) Complexes of Bis‐semicarbazone and Bis‐imine‐Substituted Phenanthroline Ligands: Solid‐State Structures, Photophysical Properties, and Anion Sensing
Author(s) -
Nadella Sandeep,
Selvakumar Paulraj M.,
Suresh Eringathodi,
Subramanian Palani S.,
Albrecht Markus,
Giese Michael,
Fröhlich Roland
Publication year - 2012
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.201201705
Subject(s) - chemistry , lanthanide , imine , luminescence , semicarbazone , phenanthroline , molecule , derivative (finance) , crystallography , stereochemistry , ion , inorganic chemistry , organic chemistry , materials science , catalysis , optoelectronics , financial economics , economics
Abstract Phenanthroline‐based hexadentate ligands L 1 and L 2 bearing two achiral semicarbazone or two chiral imine moieties as well as the respective mononuclear complexes incorporating various lanthanide ions, such as La III , Eu III , Tb III , Lu III , and Y III metal ions, were synthesized, and the crystal structures of [ML 1 Cl 3 ] (M=La III , Eu III , Tb III , Lu III , or Y III ) complexes were determined. Solvent or water molecules act as coligands for the rare‐earth metals in addition to halide anions. The big Ln III ion exhibits a coordination number (CN) of 10, whereas the corresponding Eu III , Tb III , Lu III , and Y III centers with smaller ionic radii show CN=9. Complexes of L 2 , namely [ML 2 Cl 3 ] (M=Eu III , Tb III , Lu III , or Y III ) ions could also be prepared. Only the complex of Eu III showed red luminescence, whereas all the others were nonluminescent. The emission properties of the Eu derivative can be applied as a photophysical signal for sensing various anions. The addition of phosphate anions leads to a unique change in the luminescence behavior. As a case study, the quenching behavior of adenosine‐5′‐triphosphate (ATP) was investigated at physiological pH value in an aqueous solvent. A specificity of the sensor for ATP relative to adenosine‐5′‐diphosphate (ADP) and adenosine‐5′‐monophosphate (AMP) was found. 31 P NMR spectroscopic studies revealed the formation of a [EuL 2 (ATP)] coordination species.