Synthesis, characterization, and photophysical properties of some heterodimetallic bisporphyrins of ytterbium and transition metals - Enhancement and lifetime extension of Yb³⁺ emission by transition-metal porphyrin sensitization

A series of d-f heterodimetallic bisporphyrin complexes (YbZn, YbPd, and YbPt), in which a Yb^III porphyrinate moiety is linked to a transition-metal porphyrinate moiety by a flexible three-carbon chain, were synthesized. They were fully characterized by high-resolution mass spectrometry, ¹H and ³¹P NMR spectroscopy, electronic absorption, and fluorescence methods. Variable-temperature near-infrared photoluminescence studies showed that the transition-metal porphyrinate moiety would enhance the ytterbium(III) emission centered at about 998 nm and extend its emission lifetime. YbPd and YbPt showed large two-photon absorption cross-section values because of the interaction between the porphyrin units, which caused a loss of centrosymmetry. Optical limiting investigation demonstrated that [Yb(TPP)(L _OMe)] and YbPt have comparable performance to C₆₀ by virtue of their heavy-metal effect. Our results indicate that these bisporphyrin dimetallic complexes will find valuable applications in the field of nonlinear optics.