The vibronic absorption spectra and electronic states of proflavine in aqueous solution

Theoretical study of the excitation of proflavine H-dimers in an aqueous solution: the effect of functionals and dispersion corrections

“…The photoinduced redistribution of the monomer electron density (we will not analyze it, since it is already performed in ref. 88) is much weaker than that during the dimerization of dye molecules in the ground state, and even less when the dimer is excited (Fig. 7).…”

“…As expected, the dispersion corrections did not affect the μ and M values within the same functional. An analysis of the negative solvatochromism of the PF monomer and its relation to dipole moments ( μ GS > μ EES ) was given in our previous work, 88 and we will not discuss it here, since in this case, we are primarily interested in the dimer. In the case of a dimer, both functionals and dispersion corrections significantly affect the structure of the dimer (see above), so the values of the dimer dipole moment, which is the sum of the approximately oppositely directed dipole moments of two dye molecules, have a significant scatter (especially for an excited state), so both are very sensitive to the angle between them (see Table 4).…”

“…Theoretical calculations of the absorption and emission of the PF monomer were carried out by various authors, [81][82][83][84][85][86][87] including our group. 88 In particular, according to their results, the absorption band of the PF monomer with a maximum at 444 nm is caused by the S 0 -S 1 (HOMO -LUMO) transition, and the corresponding transition moment is directed along the long chromophore axis. At the same time, a complete computational analysis of the structure, energy, and excitation of the PF dimer has not yet been performed.…”

Environmentally Driven Symmetry Breaking Quenches Dual Fluorescence in Proflavine

“…Proflavine is a small cationic organic molecule with C 2 v symmetry (see Figure ), and its photophysical properties have been well characterized by experimental ,− and theoretical studies , in various condensed-phase environments. In polar solvents, the absorption and fluorescence line shapes are featureless and close to mirror images of each other but show an unusually large Stokes shift for a small, rigid molecule that should undergo only minimal nuclear reorganization upon excitation (0.24 and 0.36 eV in methanol and water, respectively).…”

Gas-Phase Fluorescence of Proflavine Reveals Two Close-Lying, Brightly Emitting States

“…Other recent experimental and theoretical studies of proflavine’s photophysics offer further insights into relaxation processes at play within this chromophore. ,,− Of particular note are experiments that combined UV (248 nm) photodissociation with mass spectrometry to indirectly measure the average emission wavelengths and quantum yield of proflavine ions in mass-selected aqueous nanodroplets. , Distinct water loss envelopes were assigned to radiative and nonradiative decay pathways. Results indicated that in smaller nanodroplets the fluorescence of proflavine shifts to higher energies (a blue shift) and that its quantum yield increases substantially compared to proflavine ions in larger droplets and bulk solution.…”