Realizing a 4,3,3-connected tfe topology in an imidazole-linked three-dimensional covalent organic framework

Reticular chemistry relies on translating molecular geometry into periodic topology, yet many theoretically possible nets remain inaccessible because low-symmetry multinodal connectivity is difficult to crystallize. Here we report TU-433, an imidazole-linked three-dimensional covalent organic framework that realizes the first tfe topology COF and, to our knowledge, the first 4,3,3-connected reticular framework in either COFs or MOFs. Through topological simplification, an 8-connected aldehyde node and a trigonal 3-connected amine node evolve into a trinodal network containing one 4-connected and two crystallographically distinct 3-connected vertices. Crystallographic analysis, porosity measurements, spectroscopy, microscopy, electrochemical characterization, and computational modeling establish a non-interpenetrated crystalline framework with permanent microporosity, exceptional aqueous stability, polarized imidazole-rich pore environments, and measurable charge-transport capability derived from its conjugated heteroaromatic backbone. Beyond topological novelty, TU-433 functions as a robust adsorbent for anionic pollutants, delivering the highest reported Acid Orange 7 uptake among known adsorbents, together with efficient capture of Cr(vi) and Mn(vii) oxo-anions, regenerability, and activity in real textile wastewater. Mechanistic studies reveal that proton-responsive imidazole sites, π-rich pore walls, and confinement within the tfe lattice cooperate to drive adsorption. This work expands the accessible topology landscape of COFs and demonstrates how unprecedented connectivity can be coupled to practical water-remediation function.