Sensitized near-infrared luminescence from polydentate triphenylene-functionalized Nd3+, Yb3+, and Er3+ complexes
Hexa-deutero dimethylsulfoxide (DMSO-d6) solutions of terphenyl-based Nd3+, Yb3+, and Er3+ complexes functionalized with a triphenylene antenna chromophore exhibit room temperature near-infrared luminescence at wavelengths of interest for the optical telecommunication network (~ 1330 and ~ 1550 nm). The sensitizing process takes place through the triplet state of triphenylene as can be concluded from the oxygen dependence of the sensitized luminescence. A significant fraction of the excited triphenylene triplet state is quenched by oxygen, instead of contributing to the population of the luminescent state of the lanthanide ion. The luminescence lifetimes of the triphenylene-functionalized lanthanide complexes ((2)Ln) are in the range of microseconds with a lifetime of 18.6 µs for (2)Yb, 3.4 µs for (2)Er, and 2.5 µs for (2)Nd in DMSO-d6. These luminescence lifetimes seem almost completely dominated by the vibrational quenching by the organic groups in the polydentate ligand and solvent molecules, which leads to low overall luminescence quantum yields.
