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A new pyridine-bis(carboxamide)-based ligand with a bithiophene pendant, 2Tcbx, was synthesized. Its lanthanide ion (Ln III ) complexes, [Ln(2Tcbx) 2 ] 3+ , were isolated and their photophysical properties were explored. Upon excitation at 360 nm, these complexes display emission in the near-infrared (NIR) with efficiencies of 0.69% for Ln III = Yb III , 0.20% for Ln III = Nd III , and 0.01% for Ln III = Er III , respectively. Concurrent 1 O 2 formation was seen for all complexes, with efficiencies of 19% for the Yb III complex, 25% for the Nd III complex, and 9% for the Er III complex. When exciting at a longer wavelength, 435 nm, only Ln III emission was observed and larger efficiencies of Ln III -centered emission were obtained. The lack of 1 O 2 generation indicates that energy pathways involving different ligand conformations, which were investigated by transient absorption spectroscopy, are involved in the sensitization process, and enable the wavelength-dependent generation of 1 O 2 .