Abstract
Long-wavelength electronic absorption spectra of 4-hydroxy-1-naphthaldehyde, its dimer complexes, and 4-hydroxy-3-(piperidine-1-ylmethyl)-1-naphthaldehyde are investigated using time-dependent density functional theory with the TPSSh functional within a continuum solvation model. The results are correlated to recent experimental findings on solvent-, pH-and concentration-dependent absorption. It is confirmed that with decreasing wavelength the spectrum is dominated by the deprotonated (360nm-400 nm), the dimer (340nm-370 nm) and the monomer (<280 nm) species. The potential use of hydroxynaphthaldehydes for the design of tautomeric switches is discussed.