Charge transfer excited states sensitization of lanthanide emitting from the visible to the near-infra-red

Since the pioneering studies of Weissman in the 1940s, the sensitization of lanthanide luminescence via the antenna effect is becoming extremely classical. The photophysical sensitization process generally involves an energy transfer from the triplet excited state of an organic or a transition metal containing an antenna chromophore. Recently, the direct lanthanide sensitization from charge transfer excited state appears as an alternative process resulting in a red-shift of the excitation wavelength far in the visible thanks to the design of ligands with appropriate donor–acceptor charge transfer transitions. This review presents the research endeavor in this area and underlines related applications in nonlinear optics.

Visible irradiation of the ILCT induces direct sensitization from CT excited state for visible and NIR lanthanide luminescence. Design of ILCT antenna is reviewed to optimize the long wavelength lanthanide sensitization of this alternative process.Figure optionsDownload high-quality image (64 K)Download as PowerPoint slideHighlights
► Ln(III) sensitization via antenna effect can effectively proceed from the singlet ILCT excited state of the antenna.
► The lanthanide ion surrounding and the kinetic from the ILCT state are also relevant in order to “build” efficient sensitizers.
► ILCT process enables f-element sensitization with lower energy wavelength that the triplet mediated one.
► The lanthanide emission brightness is higher due to the strong absorption of the ILCT transitions.
► ILCT sensitization process makes compatible the development of lanthanide complexes for nonlinear optical applications and particularly multi-photon absorption.