Tuning the photophysical properties of lanthanide(iii)/zinc(ii) ‘encapsulated sandwich’ metallacrowns emitting in the near-infrared range

Abstract

We have created a family of ‘encapsulated sandwich’ Zn16Ln(HA)16 metallacrowns and by detailed quantitative analysis demonstrated how the nature of the hydroximate ligand impacts photophysical properties of these complexes.

Lower Energy Excitation of Water Soluble Near‐Infrared Emitting Mixed‐Ligand Metallacrowns

“…Opti-MEM cell culture medium at least up to a concentration of 25 mg/mL. In addition, we have demonstrated previously the long-term stability of Zn 16 Ln(pyzHA) 16 [8] and Zn 16 Ln-(quinoHA) 16 [10] in solution (over one month) in water or methanol, respectively, by mass-spectrometry and 1 H NMR. It is worth noting that, when the proportion of H 2 quinoHA is increased, for example, the molar ratio of H 2 pyzHA : H 2 quinoHA being 8 : 8 or 4 : 12, the obtained MCs are mainly insoluble in water, suggesting that a majority of pyzHA 2À in the MC is necessary, and the 12 : 4 molar ratio of hydroxamic acids introduced into the reactions is adequate.…”

“…Moreover, the Ln III -centered photophysical properties of Zn 16 Ln-(HA) 16 can be finely tuned by the choice of the hydroximate ligands. [10] However, only Zn 16 Ln(pyzHA) 16 MCs, which exhibit absorption in the UV range, proved to be sufficiently water soluble and therefore suitable for biological applications. We have previously shown that Zn 16 Ln(pyzHA) 16 behaves well when placed with living HeLa cells demonstrating viability values superior to 90 % upon incubation with concentrations up to 45 μM of MC for 24 and 48 h. We have also assessed minimal inhibitory concentration (MIC) of Zn 16 Ln(pyzHA) 16 against microbes such as Escherichia coli (MIC: 250 μg/mL), Staphylococcus aureus (MIC: 125 μg/mL) and Candida albicans (MIC: 2000 μg/mL), for which it displays minimal toxicity (see Supporting Information).…”

Tapered Optical Fibers Coated with Rare-Earth Complexes for Quantum Applications

“…As a result, hydrogen atoms are absent from the central ion vicinity; thus nonradiative decay channels are suppressed . In order to allow binding to the surface of the TOF, we synthesized a modified version of the metallacrown complex based on the 2-quinaldic hydroxamic acid (QHA), where we used the 2-quinoxalinehydroxamic acid (QXA) ligand , that has an additional vacant nitrogen atom, which can be harnessed for surface binding. We synthesized the ligand from its precursor 2-quinoxalinecarboxylic acid and the corresponding metallacrown complex via a modified procedure from ref .…”

Long story short: donor set symmetry in [Eu(DOTA)(H2O)]−crystals determines the electronic structure

“…The effect of this donor set is expected to be significantly different from that of the other two. 14,35…”

“…The effect of this donor set is expected to be significantly different from that of the other two. 14,35 To investigate the effect of the coordination geometry and donor set, the compounds were crystallised and the electronic properties of the central europium(III) ions were probed using luminescence spectroscopy. The results show that the three europium(III) complexes have very similar coordination geometry, but different electronic properties.…”