Direct Synthesis of Dipyrrolyldipyrrins from SNAr Reaction on 1,9-Dihalodipyrrins with Pyrroles and Their NIR Fluorescence “Turn-On” Response to Zn2+

A set of dipyrrolyldipyrrins have been efficiently synthesized from a direct SNAr reaction on 1,9-dihalodipyrrins with pyrroles and show intense absorption in the NIR region (650–800 nm, as HCl salts). Substituents on both 1,9-dihalodipyrrins and pyrroles greatly affected the reactivity of this SNAr reaction and the absorption properties of the resultant dipyrrolyldipyrrins. These dipyrrolyldipyrrins show sensitive and selective “turn-on” fluorescence response toward Zn2+.