Visible-light sensitized luminescent europium(iii)-β-diketonate complexes: bioprobes for cellular imaging

Abstract

Visible-light sensitized luminescent europium(III) molecular materials are of considerable importance because their outstanding photophysical properties make them well suited as labels in fluorescence-based bioassays and low-voltage driven pure red-emitters in optoelectronic technology. One challenge in this field is development of visible-light sensitizing ligands that can form highly emissive europium(III) complexes with sufficient stability and aqueous solubility for practical applications. Indeed, some of the recent reports have demonstrated that the excitation-window can be shifted to longer-wavelengths in europium(III)-β-diketonate complexes by appropriate molecular engineering and suitably expanded π-conjugation in the complex molecules. In this review, attention is focused on the latest innovations in the syntheses and photophysical properties of visible-light sensitized europium(III)-β-diketonate complexes and their application as bioprobes for cellular imaging. Furthermore, luminescent nanomaterials derived from long-wavelength sensitized europium(III)-β-diketonate complexes and their application in life sciences are also highlighted.

Europium and terbium thiocyanates: Syntheses, crystal structures, luminescence and magnetic properties

“…The luminescence efficiency of lanthanide compounds considerably depends on the coordinated organic ligands (the antenna effect). The strategy of this approach lies in selection of appropriate ligands for building stable complexes with high emission [6]. The presence of water molecules in the metal coordination sphere causes considerable luminescence quenching.…”

Amine‐Functionalized Silica Nanoparticles Incorporating Covalently Linked Visible‐Light‐Excitable Eu3+ Complexes: Synthesis, Characterization, and Cell‐Uptake Studies

“…[20][21][22] The development of visible-light-excitable Eu 3+ antenna complexes, which avoid the harmful UV irradiation and possess high molar-absorption coefficients, augments their attractiveness in this scenario. [23][24][25] The drawback of poor water solubility of these complexes can be overcome by incorporating them into silica nanoparticles, which provide better water dispersibility. [26][27][28] Hence, the past decade has witnessed a surge in research for the development of luminescent silica nanoparticles, whose optical properties and biocompatibilities are promising for various biological applications, by incorporating visible-light-excitable Eu 3+ complexes.…”

Syntheses, Structures, and Photophysical Properties of Eu and Lu Diketonates with a Neutral Polydentate Imidazolylmethanamine Ligand

“…The absorption spectrum of 2 quantified in extinction is shown in Figure S13, and the extinction coefficients of the bands are in the (1-2) ϫ 10 4 range. [4,10,14,[23][24][25][26][27]41,42] Metal-centered emission of Ln III complexes is normally associated with the antenna effect, [16,19] that is, energy transfer from excited ligand states into emissive triplet states of the lanthanide ions. These types of electronic transitions were previously described in various heteroligand lanthanide complexes based on β-diketonates.…”

“…17240 cm -1 ) resonant level of Eu III along with poor back energy transfer to the ligand. The Eu III complex displays a standard set of narrow bands in the range from λ = 570 to 720 nm, which correspond to the 5 D 0 Ǟ 7 F 0-5 transitions, [6,9,10,16,[28][29][30]34] and there is a sharp intense peak at λ = 612 nm ( 5 D 0 Ǟ 7 F 2 ). To experimentally determine the energy of the lowest triplet state of the NNO ligand, we have prepared and spectroscopically studied the [Gd(tta) 3 (NNO)] complex (for details, see Supporting Information).…”