Optical Properties Of Triazine Organic Polymers

Covalent organic frameworks（COFs）are a kind of porous materials with regular structures and high specific surface areas,which have broad applications in sensing,adsorption and other fields.However,traditional COFs are weakly responsive to visible light.As porous polymers with tunable electronic structure and high stability,triazine polymers are extremely important in solving environmental problems due to their unique structures.This topic studies the application of triazine polymers in the fluorescence detection of residual aromatic nitro compounds in pesticides and as photocatalysts for the degradation of toxic and stable organic dyes.First,a novel triazine-based organic polymer TTRZ with aπ-conjugated system was synthesized and characterized by BET and FTIR.The specific surface area of TTRZ was 553.63 m²g^-1with the polydisperse pore size,which was beneficial to adsorption of aromatic nitro groups compounds.In addition,TTRZ owned the perfectπ-conjugated structure and stronger rigidity,which endowed TTRZ nanoparticles the higher fluorescence intensity.Second,TTRZ was used as the fluorescent probe to detect aromatic nitro compounds.The Ksv value of 2,4,6-trinitrophenol（TNP）could reach1.15×10⁵M^-1,and the detection limit was as low as 27 ppb.Then,the fluorescence quenching mechanism of TNP on TTRZ was further elucidated.The results showed that the quenching of TNP was attributed to dynamic quenching,electron and energy transfer.In addition,the cellulose acetate membrane combined with TTRZ was prepared for TNP detection,and it was discovered that the surface fluorescence of the membrane was significant quenched after dropping TNP solution,indicating that TTRZ can visually detect aromatic nitro compounds.Finally,the covalent triazine polymer DA-CTF was synthesized by solvothermal method,and the structure of DA-CTF was characterized by SEM,FTIR and BET.The results showed that triazine group was introduced by cyano self-polymerization of monomers.DA-CTF was composed of electron donor-acceptor structure with the specific surface area of 924.14 m²g^-1.In addition,the valence band of the semiconductor was 1.68 e V and the conduction band was-0.6 e V.It was found that DA-CTF could degrade Rh B and MB under irradiation of visible light.and the rate constants（k）were0.04096 min^-1and 0.04843 min^-1respectively.Cycle tests proved that DA-CTF possessed good stability and reusability.And the organic dyes can be completely degraded into CO₂and water.Superoxide anion,hydroxyl radical and hole simultaneously acted on the degradation of organic dyes by EPR measurement.The excellent antibacterial properties of DA-CTF were also demonstrated under illumination of visible light.The results highlighted the potential of DA-CTF as a metal-free photocatalyst to degrade organic dyes and antibacterial in wastewater.