We successfully developed an unprecedented route to carbazole synthesis through a visible light-photocatalysed formal (4+2) cycloaddition of indole-derived bromides and alkynes. This novel protocol features extremely mild conditions, a broad substrate scope and high reaction efficiency.

Fe3O4@SiO2 particles were prepared on the gram-scale by selecting Na3Cit as the modifier with binary solvent and were assembled into colloidal amorphous arrays with unique and attractive optical properties for EPD.

Amorphous photonic structures (APSs) with non-iridescent, non-fading, vivid structural colors have attracted great attention in several fields. Tremendous efforts have been dedicated to developing the effective and low-cost approaches for APSs with full-color displays. Resulting from the isotropic photonic pseudogap, APSs have non-iridescent structural colors. We demonstrate that incorporating Fe3O4@SiO2 black nanoparticles into the interspace of the periodically arranged SiO2 white nanospheres can synthesize APSs with different colors. The addition of Fe3O4@SiO2 black nanoparticles can enhance the saturation of the non-iridescent structural colors of the APSs by reducing the incoherent scattering in the visible spectrum. In this case, different non-iridescent colors originate from the different diameters of the SiO2 white nanospheres, and we obtained red, orange, yellow, green, and purple APSs with high reflective index successfully. The APSs with different colors may have potential applications in coatings, cosmetics, textiles, and displays. Moreover, as we use Fe3O4@SiO2 as the additive, APSs can be recycled through its magnetic property.

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This unprecedented approach towards highly functionalized carbazoles is characterized by mild reaction conditions, a broad substrate scope, and high reaction efficiency.