Lanthanide Podands with a Short Tripodal Ligand: The Missing Piece of Puzzle

• Published in: European journal of inorganic chemistry Vol. 2021; no. 3; pp. 276 - 282
• Main Authors: Sa, Jing‐Peng, Guénée, Laure, Pal, Prodipta, Hamacek, Josef
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 22.01.2021; Wiley Subscription Services, Inc; Wiley-VCH Verlag
• Subjects: Acetonitrile; Analytical chemistry; Binding sites; Biochemistry; Biochemistry, Molecular Biology; Biophysics; Chemical Sciences; Chemistry; Chemistry, Inorganic & Nuclear; Complexation; Coordination chemistry; Crystal structure; Inorganic chemistry; Life Sciences; Ligands; Mass spectrometry; NMR; Nuclear magnetic resonance; Physical Sciences; Science & Technology; Spectrophotometry; EQUILIBRIUM-CONSTANTS; LUMINESCENCE; QUANTITATIVELY ADDRESSING COOPERATIVITY; COMPLEXES; MULTIWAVELENGTH SPECTROSCOPIC DATA; SIMPLE THERMODYNAMIC MODEL; TERBIUM; SELF-ASSEMBLY PROCESSES
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202000861

A new small tripodal ligand L2 has been synthetized and used for lanthanide complexation in acetonitrile. This podand has a short distance between the carbon anchor and the binding sites, but this structural motif still leads to the formation of stable tripodal mononuclear complexes. Indeed, the crystal structure of a C3‐symmetrical mononuclear complex with EuIII shows a helical wrapping of binding strands around the cation. Similar tripodal complexes are formed with L2 along the LnIII series. The selected ones were characterized with different techniques including NMR, mass spectrometry and spectroscopy. As shown with spectrophotometric and NMR titrations, the LnL2 complexes are moderately stable (log β∼7) but remain unchanged in large metal excess. In addition, luminescence lifetimes confirm the complexation of trivalent lanthanide in a single well‐protected coordination environment. Small Lanthanide Podands. A short tripodal ligand forms compact mononuclear complexes with lanthanide cations in acetonitrile. Their characterization in terms of structure, thermodynamic stability and photophysical properties provides valuable information on the way of designing new mono or polynuclear lanthanide‐containing supramolecular systems.