Synthesis of molecular 85 and 51 knots from azaindolyl bithiophene ligands

Abstract The synthesis of molecular topology beyond conventional symmetric knots remains a formidable challenge. Here, we report the first synthesis of the molecular 8_5 knot—a low-symmetry, representative pretzel knot with eight crossing points—via coordination-driven self-assembly. This knot was assembled from eight 4-azaindolyl ligand strands (L) and eight binuclear metal blocks (E1-Rh). These components intertwine in three-dimensional space in an alternating up-and-down fashion, forming a closed loop featuring eight crossings. Successful construction of this elusive 8_5 knot relies on our newly developed 4-azaindolyl ligand strand, whose unique electronic and steric properties enable tunable topological organisation. Exploiting this ligand design, we further systematically synthesized two 5_1 torus knots in high yields by tuning the size of the binuclear metal motifs, thereby validating the platform's broad applicability. This study fills a key gap concerning low-symmetry eight-crossing molecular knots and establishes a versatile route to accessing diverse molecular topologies.