Investigation of H-bond on fluorescence changes in benzene derivations and different acceptor systems

In this study, benzene derivatives of phenol and naphtol were selected as donor systems and mixed with dioxane and TEA (triethylamine), which were chosen as acceptors. H-bond formation in the phenol-triethylamine binary system was investigated by both UV absorption and emission spectroscopies. The changes in the absorption and emission spectra by H-bond formation and the equilibrium of the H-bonded complexes were studied at both the ground and excited states. In addition, equilibrium constants at different temperatures and thermodynamic properties related to equilibrium (enthalpy, fere energy change and entropy values of H-bond formation) were calculated. A shift to longer wavelengths and differences in absorption and fluorescence intensities in the absorption and emission spectra were observed. Moreover, H-bond formation in various solvents with different dielectric constants was investigated. Changes in entropy related to the formation of hydrogen bonded complexes generally had negative values at both ground and excited states. These values were observed to increase with the increase in the dielectric constants of the solvent systems; therefore, H-bonded complexes grew more stable with the increase in the dielectric constants of the solvent systems.

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