Organic micro/nanospheres assembled from a [2 + 2] Schiff base macrocycle for efficient adsorption of zinc ions and dyes

The solid micro/nanospheres of uniform size precipitated from the Schiff base condensation reaction showed good adsorption capacity towards Zn 2+ , and displayed satisfactory adsorption capacities and good reusabilities towards the dyes CV, MB, and NR. • Macrocycle M exhibited AIEE characteristics in DMF/water and displayed a highly selective recognition of Zn 2+ in DMF. • The micro/nanospheres of M showed an adsorption capacity of 121 mg·g −1 towards Zn 2+ . • The micro/nanospheres displayed satisfactory adsorption capacities and good reusabilities towards the dyes CV, MB, and NR. A Schiff base macrocycle ( M ) containing both isophthalamide and bissalicylaldehyde scaffolds was successfully designed and synthesized. M exhibited typical aggregation-induced enhanced emission characteristics in a mixed solvent of DMF/water, and showed high selectivity for the recognition of Zn(II) over other metal ions. The binding process, binding ratio, and association constant of M with Zn(II) were estimated through UV–vis and fluorescence spectra titrations, isothermal titration calorimetry, and 1 H NMR titration experiments, and the detection limit towards Zn(II) was calculated as 1.03 × 10 −7 mol·L −1 . Interestingly, a large amount of micro/nanospheres of M with remarkable size uniformity were obtained from the reaction medium with sulfuric acid as a catalyst. On the basis of exploring the formation process of the micro/nanospheres and the key factors affecting their morphology and size, the Zn(II) and dye adsorption experiments were carried out. The results indicated that the micro/nanospheres of M can be applied to Zn(II) and dye adsorption with satisfactory removal rates.