Single Crystals of Double-Stranded, Entwined, Helical Metallopolymers With Hexanuclear Zirconium Knots Achieved by...

Synthetic one-dimensional (1D) helical polymers are an intriguing class of functional materials that have been pursued for decades. Despite numerous reports of single-stranded helical polymers, the synthesis of double-stranded, entwined helical polymers with deterministic atomic coordinates remains a significant challenge. Herein, through judicious linker conformation engineering, we target two double-stranded helical metallopolymer single crystals that consist of robust hexanuclear Zr₆O₄(OH)₄ clusters and inherently helical methano- or ethano-Tröger base (TB) scaffolds. The racemic TB linkers undergo spontaneous resolution and narcissistic self-sorting to from large single crystals of helical metallopolymer conglomerate, which can be rendered homochiral by employing enantiopure TB linkers. Characterization by single-crystal X-ray diffraction showed that, the two homochiral strands are bound together through Zr₆-carboxylate knots, which further arrange with respect to 6₁ screw axis to engender 1D hexagonal channels. The resulting chemically stable metallopolymer conglomerates were demonstrated to be capable of catalyzing the normally acidic hydrolysis of orthoformates in basic solution with exceptional reactivity and selectivity, while the homochiral version was shown to be a remarkable chiral fluorescent sensor for amino alcohols. Our work, therefore provides an unparalleled example where linker conformation engineering serves as powerful tool for architecting sophisticated helical polymeric structures and achieving enzyme-mimic catalysis and recognition.