Blue-light emission of mesoporous SBA-15 covalently bonded with carbazole chromophore

Much attention has been paid to carbazole derivatives for their potential applications as optical materials. For the first time, the blue-light-emitting carbazole chromophore has been covalently bonded to the ordered mesoporous SBA-15 (The resultant hybrid mesoporous materials are denoted as carbazole–SBA-15) by co-condensation of tetraethoxysilane (TEOS) and prepared compound 3-[N-3-(triethoxysilyl)propyl]ureyl-9-ethyl-carbazole (denoted as carbazole–Si) in the presence of Pluronic P123 surfactant. The results of 1H NMR and Fourier transform infrared (FTIR) reveal that carbazole–Si has been successfully synthesized. Small-angle X-ray diffraction patterns (XRD) and Nitrogen (N2) adsorption/desorption measurements were employed to characterize the mesostructure of carbazole–SBA-15. Solid-state 29Si magic-angle spinning (MAS) NMR was used to confirm the preservation of the carbazole group and estimate the degree of hydrolysis-condensation. Photoluminescence (PL) measurements show that carbazole–SBA-15(0.07) [carbazole–Si:(TEOS+carbazole–Si) molar ratio is 0.07] hybrid mesoporous material exhibits a monomeric emission in the “light blue” region with a PL quantum yield ∼31%. Compared with carbazole–Si, the Icar/Ccar (relative luminescence intensity divided by the content of carbazole) of carbazole–SBA-15(0.07) increases 24 times. The luminescence decays for 3-amino-9-ethyl-carbazole (denoted as carbazole–NH2) and carbazole–Si are single-exponential functions of time, while those for carbazole–SBA-15 mesoporous materials are fitted by double-exponential functions. The stability studies on carbazole–Si and carbazole–SBA-15(0.07) show that the carbazole chromophore in the resultant hybrid mesoporous material exhibits better thermal stability than in carbazole–Si compound. The excellent luminescent properties and thermal stability enable the hybrid mesoporous material to have potential use as blue-light-emitting material in optical field.