Pyrene-containing Macrocyclic Triazoliums For Anion Recognition

Macrocyclic receptors have excellent size matching effects and multiple binding sites,and have attracted wide interest in the field of supramolecular chemistry research.Click reaction is considered an efficient and flexible strategy for the preparation of macrocyclic receptors with different configurations due to its high efficiency,mild reaction conditions and easy operation.Since anions play an important role in environmental,industrial production,and biology,the development of artificial receptors for anion recognition has attracted the attention of chemists.In this paper,a series of triazolium macrocyclic receptors with different anions recognition sites were synthesized by click reaction.Ultrasonic absorption spectroscopy,fluorescence spectroscopy and ¹H NMR were used to explore the sensing ability and recognition mechanism of the target molecules.The details are listed as follows:1.A novel fluorescent macrocyclic receptor 2-1 containing amide（NH）and triazolium（CH）⁺multiple recognition sites was synthesized by click reaction.The UV-visible spectroscopy and fluorescence spectroscopy can be used to ratio fluorescent sense dihydrogen phosphate（the monomer peak decreases and the aggregation state peaks upward）.For other anions such as F^-,Cl^-,Br^-,I^-,AcO^-,the fluorescence quenching response is shown,and the fluorescence recognition ability I^->Br^->Cl^->F^->AcO^-is opposite to the Hofmeister sequence of the anion.The mechanism of complexation between the acceptor molecule and the anion was studied by ¹H NMR titration.As well as Pi was selectively identified.its binding mode was studied by DFT calculation.2.Neutral macrocyclic triazole receptor 3-2 and cationic macrocyclic triazolium receptor 3-1 containing pyrene fluorophore were successfully synthesized by1.3-dipolar cycloaddition reaction using extreme dilution method.The macrocyclic triazole receptor 3-2 can selectively recognize Hg²⁺with larger complexation constant and lower detection limit.Its ionic macrocyclic triazolium receptor 3-1 can be used to ratio sense phosphate anions（Pi,PPi）,and two different modes of complexation are described.Between the complexation constant size(K_PPi>K_Pi)and the shift value of proton hydrogen in 1HNMR titration（H_a、H_b、H_c>H_a′、H_b′、H_c′）are proved trend of complexation between ions and receptor（PPi>Pi）.the drastic change of fluorescence and ultraviolet after adding Pi is due to complex 3-1·Pi itself polymerizes to form a dimer.3.A triazolium-based macrocyclic probe molecule 4-1 with ratiometric fluorescence recognition for ATP was synthesized.The combination of fluorescence spectroscopy,ultraviolet absorption spectroscopy,¹HNMR titration and dynamic light scattering（DLS）proved the host-guest complex formed between ATP and receptor is more likely to self-assemble to form denser aggregates in aqueous solution.Achieving favourable detection to ATP in vitro or in vivo,As well as a blue-green dual-channel response in vivo.