Synthesis of Vinylene‐Linked Two‐Dimensional Conjugated Polymers via the Horner–Wadsworth–Emmons Reaction

Abstract

In this work, we demonstrate the first synthesis of vinylene‐linked 2D CPs, namely, 2D poly(phenylenequinoxalinevinylene)s 2D‐PPQV1 and 2D‐PPQV2, via the Horner–Wadsworth–Emmons (HWE) reaction of C 2‐symmetric 1,4‐bis(diethylphosphonomethyl)benzene or 4,4′‐bis(diethylphosphonomethyl)biphenyl with C 3‐symmetric 2,3,8,9,14,15‐hexa(4‐formylphenyl)diquinoxalino[2,3‐a:2′,3′‐c]phenazine as monomers. Density functional theory (DFT) simulations unveil the crucial role of the initial reversible C−C single bond formation for the synthesis of crystalline 2D CPs. Powder X‐ray diffraction (PXRD) studies and nitrogen adsorption‐desorption measurements demonstrate the formation of proclaimed crystalline, dual‐pore structures with surface areas of up to 440 m2 g−1. More importantly, the optoelectronic properties of the obtained 2D‐PPQV1 (Eg=2.2 eV) and 2D‐PPQV2 (Eg=2.2 eV) are compared with those of cyano‐vinylene‐linked 2D‐CN‐PPQV1 (Eg=2.4 eV) produced by the Knoevenagel reaction and imine‐linked 2D COF analog (2D‐C=N‐PPQV1, Eg=2.3 eV), unambiguously proving the superior conjugation of the vinylene‐linked 2D CPs using the HWE reaction.