Intermolecular Hydrogen Bonding Modulates Triplet-Triplet Annihilation Upconversion in a Cationic Sensitizer as Revealed by Transient Electronic Spectroscopy.
Metal-free triplet-triplet annihilation upconversion (TTA-UC) under long-wavelength excitation rules out metal toxicity and improves biocompatibility, showing great potential for biomedical use of photon upconversion materials. Intermolecular hydrogen bonding commonly occurs in biological environments, yet its effects...