New Pt(II) and Pd(II) complexes with donor-acceptor Schiff bases are conveniently prepared in only two steps. The complexes efficiently absorb in the red part of the spectrum (epsilon > 10(5) M-1 cm(-1)) and show moderate to strong room-temperature phosphorescence in the near-infrared (NIR) region. Particularly, Pt(H) complexes possess phosphorescence quantum yields (Phi) of similar to 10%, but the emission of the respective Pd(II) complexes is less efficient (Phi approximate to 1%-2%). The complexes exhibit solvatochromic behavior, in which the absorption and emission spectra shift bathochromically in polar solvents. The Pt(II) complexes are embedded in polystyrene to produce oxygen-sensing materials. The Pd(II) and Pt(II) complexes are demonstrated to be efficient sensitizers in triplet-triplet annihilation-based upconversion systems.