Schwich, TorstenBarlow, AdamCifuentes, MarieSzeremeta, JSamoc, MarekHumphrey, Mark2020-12-202020-12-200947-6539http://hdl.handle.net/1885/218414Very large molecular two- and three-photon absorption cross-sections are achieved by appending ligated bis(diphosphine)ruthenium units to oligo(p-phenyleneethynylene) (OPE)-based “stars” with arms up to 7 phenyleneethynylene (PE) units in length. Extremely large three- and four-photon absorption cross-sections, through the telecommunications wavelengths range and beyond, are obtained for these complexes upon optimizing OPE length and the ruthenium-coordinated peripheral ligand. Multi-photon absorption (MPA) cross-sections are optimized with stars possessing arms 2 PE units in length. Peripheral ligand variation modifies MPA merit and, in particular, 4-nitrophenylethynyl ligand incorporation enhances maximal MPA values and “switches on” four-photon absorption (4PA) in these low molecular-weight complexes. The 4-nitrophenylethynyl-ligated 2PE-armed star possesses a maximal four-photon absorption cross-section of 1.8×10−108 cm8 s3 at 1750 nm, and significant MPA activity extending beyond 2000 nmapplication/pdfen-AU201710.1002/chem.2017020392020-11-23