Lanthanide(III) Complexes of Bis‐semicarbazone and Bis‐imine‐Substituted Phenanthroline Ligands: Solid‐State Structures,Photophysical Properties,and Anion Sensing |
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Authors: | Sandeep Nadella Dr. Paulraj M. Selvakumar Dr. Eringathodi Suresh Dr. Palani S. Subramanian Prof. Dr. Markus Albrecht Dr. Michael Giese Dr. Roland Fröhlich |
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Affiliation: | 1. Analytical Science Division, Central Salt and Marine Chemicals Research Institute (CSIR), Bhavnagar – 364?002, Gujarat (India);2. Institut für Organische Chemie, RWTH Aachen University, Landoltweg 1, 52070 Aachen (Germany);3. Organisch‐Chemsiches Institut der Universit?t Münster, Corrensstrasse 40, 48149, Münster (Germany) |
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Abstract: | Phenanthroline‐based hexadentate ligands L1 and L2 bearing two achiral semicarbazone or two chiral imine moieties as well as the respective mononuclear complexes incorporating various lanthanide ions, such as LaIII, EuIII, TbIII, LuIII, and YIII metal ions, were synthesized, and the crystal structures of [ML1Cl3] (M=LaIII, EuIII, TbIII, LuIII, or YIII) complexes were determined. Solvent or water molecules act as coligands for the rare‐earth metals in addition to halide anions. The big LnIII ion exhibits a coordination number (CN) of 10, whereas the corresponding EuIII, TbIII, LuIII, and YIII centers with smaller ionic radii show CN=9. Complexes of L2, namely [ML2Cl3] (M=EuIII, TbIII, LuIII, or YIII) ions could also be prepared. Only the complex of EuIII 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. 31P NMR spectroscopic studies revealed the formation of a [EuL2(ATP)] coordination species. |
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Keywords: | chirality crystal structures lanthanides phosphate ions sensors |
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