Emissive Organogel Mediated Construction of Hydrazide Linked Flexible Covalent Organic Polymer for the Separation of Aniline for Water Purification

A flexible covalent organic polymer (COP) has been successfully synthesized via dynamic covalent gel (DCG) formation through imine condensation reaction between 6-hydrazinonicotinic hydrazide hydrate and benzene-1,3,5-tricarboxaldehyde within 7 min. Herein, an emissive organogel mediated protocol has been developed for the construction of amorphous polymer (COP), selectively in N,N-dimethyl acetamide (DMA). Interestingly, two non-emissive building block units have been engaged for the construction of green emissive COP-gel. The green emission of COP-gel is generated by the intermolecular H-bonding assisted aggregation induced emission phenomenon. The dried COP can efficiently adsorb aniline molecules into its cavities and separate them from binary mixtures of aniline/nitrobenzene and aniline/water, respectively. The UV-vis and emission spectroscopy of COP solution in DMA with the addition of nitrobenzene and aniline have been further investigated. The dispersion solution of COP in DMA shows bluish-white light emission. Photophysical investigation of COP in DMA suggests that the origin of the distinct emission quenching of COP for aniline and nitrobenzene is different. Our findings mark a significant step forward in the development of functionalized COP as a material for the separation of aniline from miscible binary solvent mixtures.