Proton phototransfer reactions in aprotic solvents

Solvatochromism of β-Naphthol

“…47 These frequencies are also collected in Table 1. A similar red shift in basic solvents such as tetrahydrofuran (THF), Et 2 O, and ACN has been previously observed 13 and attributed to HBing.…”

“…Early experiments centered on steady-state absorption and fluorescence measurements. ,,− By use of the Förster cycle, these spectroscopic data successfully predicted the excited-state acidity constant from the ground-state p K a value and the excited-state energy difference, E RO − − E ROH , between the unprotonated and protonated forms of the photoacid. Hence the more blue-shifted (red-shifted) the acid (anion) fluorescence, the stronger the excited-state acidity.…”

“…31,32 On the other hand, the formation of bimolecular HBed complexes between naphthols and various proton acceptors in nonpolar solvents is well documented. 4,6,10,13,[33][34][35] In the presence of ethers and esters, both absorption and emission bands of naphthols shift to the red. 10 Addition of amines to solutions of naphthols in low-polarity solvents leads to the appearance of a new, low-energy fluorescence band.…”

Spectral-Luminescent Properties of Neutral and Ionic Cresols

“…The change in the relative quantum yield of fluorescence of the base and the linked acid is determined by the acid-base equilibrium constants of an aromatic compound in the ground and singlet excited states and the competition between the direct and inverse reactions and the deactivation of the excited base and the linked acid. The large change in pK a of aromatic compounds on excitation is well understood for objects possessing convenient spectral characteristics [10][11][12][13][14]. However, to this point the possibility of formation of cationic forms of cresols has not been discussed in the literature, despite the fact that both anthropogenic [15] and natural cresols [16] are present in large amounts in the atmosphere [17] and hydrosphere [18].…”