Light‐Harvesting Ytterbium(III)–Porphyrinate–BODIPY Conjugates: Synthesis, Excitation‐Energy Transfer, and Two‐Photon‐Induced Near‐Infrared‐Emission Studies

Abstract

Based on a donor-acceptor framework, several conjugates have been designed and prepared in which an electron-donor moiety, ytterbium(III) porphyrinate (YbPor), was linked through an ethynyl bridge to an electron-acceptor moiety, boron dipyrromethene (BODIPY). Photoluminescence studies demonstrated efficient energy transfer from the BODIPY moiety to the YbPor counterpart. When conjugated with the YbPor moiety, the BODIPY moiety served as an antenna to harvest the lower-energy visible light, subsequently transferring its energy to the YbPor counterpart, and, consequently, sensitizing the Yb(III) emission in the near-infrared (NIR) region with a quantum efficiency of up to 0.73% and a lifetime of around 40 μs. Moreover, these conjugates exhibited large two-photon-absorption cross-sections that ranged from 1048-2226 GM and strong two-photon-induced NIR emission.

Near-infrared fluorescent probes in cancer imaging and therapy: an emerging field

“…Currently, two main strategies are adopted to shift BODIPY into NIRF dyes, modifying the phenyl rings and merging the 3-and 5-phenyl rings with the aza-BODIPY core, which forms six-membered rings and reduces the torsion angles formed by peripheral phenyl groups and the central core. 26,27 Enhancement of co-planarity between phenyls and the central core results in NIR bathochromic shifts, probably due to electron delocalization. 28 Diphenyl dithienyl aza-BODIPY was synthesized through the substitution of phenyl groups by thiophene in aza-BODIPY.…”

Near-IR Two Photon Microscopy Imaging of Silica Nanoparticles Functionalized with Isolated Sensitized Yb(III) Centers

“…Only a few notable examples of red emitters have been reported. [14][15][16][17] Ytterbium complexes are ideal candidates for NIR-to-NIR biphotonic microscopy because of the 2 F 5/2 → 2 F 7/2 ytterbium (III) transition around 1000 nm, an emission at higher wavelength than the incident laser. 1 1 8 8 , 1 1 9 9 This emission has been used for 3D imaging of a mouse brain vascular network.…”

Highly Emitting Near-Infrared Lanthanide “Encapsulated Sandwich” Metallacrown Complexes with Excitation Shifted Toward Lower Energy

“…Captured excitation energy is then transferred to the lanthanide ion which, in turn, lights up with characteristic emission bands. 20 Different NIR luminescent lanthanide molecules and materials have been created based on mononuclear complexes with macrocyclic and acyclic ligands 21−23 and, more recently, nanoparticles, 24−26 dendrimers, 27−31 mesoporous solids, 32−34 MOFs, 35−38 and 3d-4f heterometallic clusters. 39−43 Quantitative sensitization efficiencies can be achieved; 44 however, despite numerous efforts, the highest reported overall quantum yields for NIR-emitting lanthanide complexes containing C–H bonds are inferior: 3.8% for Yb 3+ , 0.42% for Nd 3+ , and 0.033% for Er 3+ .…”