Aromatic carbon nitride (PhCN) has become an important luminescent material due to its excellent optical properties and has attracted attention in photoluminescence and electroluminescence applications. Normally, PhCN is synthesized by thermal polymerization of 2,4-diamino-6-phenyl-1,3,5-triazine (DPT). However, the polymerization mechanism is still unclear. Here we investigated the polymerization process of 2,4-diamino-6-phenyl-1,3,5-triazine (DPT) at different temperatures. The results indicate that at 350 ℃, DPT decomposes into benzonitrile and cyanamide; the phenyl group does not participate in polymerization and the cyanamide polymerizes into melem. As the temperature increases to 370 ℃, the phenyl group gradually engages in polymerization, while the generation of melem diminishes and eventually ceases at 410 ℃. The characterization of its optical properties indicates that the phenyl substituent leads to an increase in the degree of conjugation and promotes the π-electron delocalization, resulting in a redshift in the UV-vis absorption and PL spectra. This work provides foundational insights into the synthesis, structure, and optical properties of PhCN, which are expected to facilitate further exploration and broader applications.
Anye Shi,Huihui Li,Shu Yin,Bin Liu,Jiachi Zhang,Yuhua Wang
Single layer g-C 3 N 4 could be obtained from a protonic acid treatment of g-C 3 N 4 or a new sandwich-like orientation growth of melamine. Through the self-assembly of melamine and polyacrylamide by hydrogen bonds and electrostatic interactions, g-C 3 N 4 , with extended planarized atomic single layer, exhibits superiority in both photocatalytic hydrogen evolution and photocatalytic degradation under visible light irradiation. Besides low efficiency, the acid exfoliation will destroy the delocalized π-system by inducing O atoms. The decrease of conjugation degree increases the optical gaps, making it hard for g-C 3 N 4 to capture photons. On the contrary, the facile sandwich-like orientation growth of melamine highly keeps the conjugation degree of g-C 3 N 4 and extends its delocalized π-system. Such single layer g-C 3 N 4 is more active even better than N-doped TiO 2 under visible light irradiation.
In this study, two fluorescence conjugated microporous polymers based on perylene tetraanhydride bisimide (DP4A0 and DP4A2) were prepared via Sonogashira–Hagihara cross-coupling polymerization for the efficient detection of o-nitrophenol (o-NP). They were well characterized via FT-IR, solid state 13C NMR, elemental analysis, and other material characterization techniques. The experiments proved that both CMPs possess high thermal and chemical stability and a porous nature with Brunauer–Emmett–Teller (BET) specific surface areas of 41.3 and 402.1 m2 g−1. Importantly, owing to signal amplification by the conjugated skeleton, DP4A0 and DP4A2 exhibit extremely high sensitivity to o-NP with Ksv values of 1.83 × 104 and 1.69 × 104 L mol−1 and limits of detection of 5.73 × 10−9 and 7.36 × 10−9 mol L−1, respectively. The sensing performance of DP4A0 and DP4A2 was dependent on the position of crosslinking points and crosslinking density. Finally, super amplified quenching was considered the electron transfer mechanism and hydrogen bond interactions were also present.
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