N-2-Aryl-1,2,3-triazoles: A Novel Class of UV/Blue-Light-Emitting Fluorophores with Tunable Optical Properties

The N-2-aryl-1,2,3-triazole derivatives (NATs) were developed as a new class of UV/blue-light-emitting fluorophores. Though both N-1-aryl-1,2,3-triazoles and N-2-aryl-1,2,3-triazoles gave strong photo absorption under excitation at 330 nm, only the N-2-analogous showed strong fluorescence emission in the UV/blue range with high efficiency in various solvents (quantum yield F around 0.3-0.5). Significant substituted group effects were observed, allowing tunable optical properties with emission (lambda(max)) from 350-400 nm and Stokes shift from 3893 nm. The computational studies along with X-ray crystal structures indicated the significance of the effective conjugation between triazole ring and aryl groups on the N-2 position. The planar intramolecular charge transfer (PICT) mechanism was proposed, which was supported by solvent effect studies. Simple derivatizations gave NAT-modified lysine and strong UV/blue emitting bis-NAT (Phi = 0.76, lambda(max) = 390), which suggested the great potential of this new class of fluorophores in biological and material science research.