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Free, publicly-accessible full text available February 10, 2024
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Free, publicly-accessible full text available October 3, 2023
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Two efficient lanthanide ion sensitizers 2,6-bis(oxazoline)-4-phenyl-pyridine (PyboxPh, 1 ) and 2,6-bis(oxazoline)-4-thiophen-2-yl-pyridine (Pybox2Th, 2 ) were synthesized. 1 crystallizes in the monoclinic space group P 21/ c with cell parameters a = 16.3794(4) Å, b = 7.2856(2) Å, c = 11.7073(3) Å, β = 97.229(1)° and V = 1385.97(6) Å 3 . 2 crystallizes in the monoclinic space group P 21/ n with cell parameters a = 5.9472(2), b = 16.0747(6), c = 14.3716(5) Å, β = 93.503(1)° and V = 1371.35(8) Å 3 . Photophysical characterization of 1 shows that its triplet state energy is located at 22 250 cm −1 and efficient energy transfer is observed for Eu III and Tb III . Solutions of [Ln(PyboxPh) 3 ] 3+ in dichloromethane display an emission efficiency of 37.2% for LnEu and 24.0% for LnTb. The excited state lifetimes for Eu III and Tb III are 2.227 ms and 723 μs, respectively. The triplet state energy of 2 is located at 19 280 cm −1 and is therefore too low to efficiently sensitize Tb III emission. However, the sensitization of Eu III is effective, with an emission quantum yield of 14.5% and an excited state lifetime of 714 μs. This shows that themore »
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We report the solution structure of a europium-nicotianamine complex predicted from ab initio molecular dynamics simulations with density functional theory. Emission and excitation spectroscopy show that the Eu 3+ coordination environment changes in the presence of nicotianamine, suggesting complex formation, such as what is seen for the Eu 3+ –nicotianamine complex structure predicted from computation. We modeled Eu 3+ –ligand complexes with explicit water molecules in periodic boxes, effectively simulating the solution phase. Our simulations consider possible chemical events ( e.g. coordination bond formation, protonation state changes, charge transfers), as well as ligand flexibility and solvent rearrangements. Our computational approach correctly predicts the solution structure of a Eu 3+ –ethylenediaminetetraacetic acid complex within 0.05 Å of experimentally measured values, backing the fidelity of the predicted solution structure of the Eu 3+ –nicotianamine complex. Emission and excitation spectroscopy measurements were also performed on the well-known Eu 3+ –ethylenediaminetetraacetic acid complex to validate our experimental methods. The electronic structure of the Eu 3+ –nicotianamine complex is analyzed to describe the complexes in greater detail. Nicotianamine is a metabolic precursor of, and structurally very similar to, phytosiderophores, which are responsible for the uptake of metals in plants. Although knowledge that nicotianamine binds europiummore »
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A new naphthylsalophen and its 3 : 2 ligand-to-lanthanide sandwich-type complexes were isolated. When excited at 380 nm, the complexes display the characteristic metal-centred emission for Nd III , Er III and Yb III . Upon 980 nm excitation, in mixed lanthanide and the Er complexes, Er-centred upconversion emission at 543 and 656 nm is observed, with power densities as low as 2.18 W cm −2 .