Effect of protonation on the photophysical properties of 4-substituted and 4,7-disubstituted quinazoline push-pull chromophores

Abstract

White-light emission from single molecular systems has attracted a great deal of attention due to their advantages over multicomponent emitters. Azaheterocyclic push-pull derivatives have been demonstrated to be white emitters by combining neutral and protonated forms in the appropriate ratio, although limited cases of white-light emission have been reported from quinazoline derivatives. Herein, we describe a series of push-pull 4-substituted and 4,7-disubstituted quinazolines that show white photoluminescence both in solution and in the solid state. All of the materials were prepared by straightforward Suzuki-Miyaura crosscoupling reactions and the compounds exhibited remarkable emission solvatochromism. In some cases the presence of acid prompted the appearance of emission bands of complementary colors. Thus, multicolor photoluminescence, including white light, could be finely tuned by the controlled protonation of the electron-deficient quinazoline ring.

Phosphorescent cyclometalated platinum(ii) complexes with phenyldiazine N^C ligands

“…The Suzuki–Miyaura cross-coupling reaction was used according to a method previously reported in the literature (ESI, Scheme S1†). 16–18 The N^C cyclometalated chloro-Pt( ii ) complexes 1–24 were prepared according to the well-established method of synthesis for the traditional counterparts, by treating the Pt( ii ) μ-chloro-bridged dimer complexes with the pyridine, 4-methoxy-pyridine or pyrimidine ancillary ligand, in low to moderate yields (Schemes 1–4). 14 These air-stable compounds were isolated in high purity as solids after column chromatography on silica gel with the appropriate eluent.…”

“…The diazine rings exhibit a stronger π-deficient character than pyridine due to the presence of a second N atom and have been used as the attracting part in numerous push–pull structures. 16…”

Exploring Solvent and Substituent Effects on the Excited State Dynamics and Symmetry Breaking of Quadrupolar Triarylamine End-Capped Benzothiazole Chromophores by Femtosecond Spectroscopy

“…FU was used for the study of the excited state dynamics in the fs–ps time scale. The method has been described in detail previously. , Briefly, the samples were excited at 400 nm by the second harmonic of a Ti:sapphire mode-locked femtosecond laser (800 nm, 80 fs pulse duration, 80 MHz repetition frequency). The samples were put in rotating cells with a 1 mm path length.…”

4‐substituted push‐pull quinazoline chromophores with extended π‐conjugated linker

“…Often, protonation of pushpull azaheterocyclic chromophores leads to extinction of emission, but in some cases red-shifted emission is observed and white light emission can be observed through partial protonation by combination of blue emission of the neutral form and orange/red emission of protonated form [21][22][23] and have found application as white organic light emitting diodes [20]. The emission properties of push-pull quinazoline chromophores are therefore highly sensible to their environment [20,24,25].…”