United Complexes or [2]Catenanes: Curvature-Controlled Cooperative π-Coordination Mimicking θ-Curve Motifs
Year: 2026
Type: preprint
Abstract: Control over the solid-state self-assembly of (M 3 L 2 ) 2 -type entangled complexes (M = Cuᴵ, Agᴵ) and interlocked [2]catenanes was achieved through structural modification of the curved tripodal arms of triarylmethane-based ligands (L). When 3-pyridyl groups served as terminal coordination donors on appropriately curved tripodal arms, cooperative metal–acetylene π-coordination, reminiscent of the secondary cross-linking found in nontrivial θ -curve motifs of entangled proteins, generated additional intercomponent connectivity and bridged the two M 3 L 2 cages to form a “united” complex. In contrast, incorporation of 4-pyridyl donors reduced the curvature of the tripodal arms and afforded a normal [2]catenane lacking such inter-cage cross-linking. Furthermore, insertion of an m -phenylene–ethynylene spacer produced a unique dissymmetric [2]catenane in the crystalline state. These results demonstrate that subtle changes in ligand geometry can regulate secondary connectivity while preserving the underlying (M 3 L 2 ) 2 entangled framework, thereby providing access to distinct interlocked architectures. The introduction and control of θ -curve-like secondary linkages thus offer a new design principle for coordination-driven nanostructures based on molecular entanglement.
Source: ChemRxiv
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214676557