Diverse Self-Assembly from Predesigned Conformationally Flexible Pentanuclear Clusters Observed in a Ternary Copper(II)–Triazolate–Sulfoisophthalate System: Synthesis, Structure, and Magnetism

Self-assembly from the predesigned CuII5 secondary building unit (SBU) in the ternary CuII–triazolate–sulfoisophthalate system generates three interesting magnetic samples: an open pillared-layer framework with nanosized CuII30 metallamacrocycle-based sublayer (1), a (3,6)-connected 2-fold interpenetrating network consisting of alternating CuII5 and CuII1 cores (2), and a (4,8)-connected architecture constructed from centrosymmetric CuII7 clusters and four-branched 5-sulfoisophthalate (sip3–) connectors (3). These various structures significantly result from the variable connectivity and the slight expansion of the predetermined conformationally flexible CuII5 SBUs. Furthermore, these intriguing structural motifs in 1–3 essentially induce different magnetic phenomena. A field-dependent metamagnetic transition from antiferromagnetic ordering to weak ferromagnetism is observed in the frustrated CuII30-based sublayer of 1. The paramagnetic CuII1 core in 2 virtually contributes to an S = 1/2 spin ground state due to the completely compensated magnetic moment in the 1,2,3-triazolate (ta–)-bridged CuII5 cluster containing ribbon. In contrast, strong antiferromagnetic interactions in the locally centrosymmetric CuII7 cluster lead to an overall S = 1/2 spin ground state of 3. Thus, the SBU-derived self-assembly strategy provides important hints for polymetallic cluster based high-dimensional magnetic materials, which also brings a new vision for the design and construction of novel functional materials.