How To Make Nitroaromatic Compounds Glow: Next-Generation Large X-Shaped, Centrosymmetric Diketopyrrolopyrroles.

摘要: Red-emissive π-expanded diketopyrrolopyrroles (DPPs) with fluorescence reaching λ=750 nm can be easily synthesized by a three-step strategy involving the preparation of diketopyrrolopyrrole followed N-arylation and subsequent intramolecular palladium-catalyzed direct arylation. Comprehensive spectroscopic assays combined first-principles calculations corroborated that both N-arylated fused DPPs reach locally excited (S1 ) state after excitation, internal conversion to states solvent structural relaxation, before eventually undergoing intersystem crossing. Only structurally relaxed is fluorescent, lifetimes in range several nanoseconds tens picoseconds nonpolar polar solvents, respectively. The correlate quantum yields, which from 6 % 88 % solvents 0.4 % 3.2 % solvents. A very inefficient (T1 population responsible for yields as high fully DPP