Solid-State Photoluminescence of Diphenylnaphthalenes Studied by Photophysical Measurements and Crystallographic Analysis.

Thanks to recent developments in spectrophotometric instruments, the spectra, quantum yields (Φ), and lifetimes () of photoluminescence from organic and inorganic compounds can be readily determined not only in solution but also in the solid state. It is known that naphthalene emits fluorescence in solution, but not in the solid state. In a previous paper, we reported that solid-state emission can be seen from biaryl compounds comprised of chromophores that show no emission in the solid state. In this work, we prepared diphenylnaphthalenes (DPNs), and the spectra and the Φ and values of fluorescence were determined in solution and the solid state, as well as the crystallographic features. The 2,6-Diphenylnphthalene (26DPN) showed solid-state emission in the wavelength region for longer than those in solution, while the emission spectra of the others in the solid state were similar to those in solution. The crystal structure of 26DPN belonged to a herringbone motif, whereas those of the others were column-stacked structures. Based on these spectroscopic and crystallographic facts, the relationship between the crystal motif and the emission features in the solid state is discussed.