Template‐Free Self‐Assembly of Molecular Trefoil Knots and Double Trefoil Knots Featuring Cp*Rh Building Blocks

Abstract

on the occasiono fhis 65th birthday Abstract: Understanding and controlling the topology of self-assembled structures plays af undamentalr ole in supramolecular chemistry. Herein, the preparation of as eries of tetranuclear metallarectangles and hexanuclear trefoil knots featuring Cp*Rh buildingb locks by template-free self-assembly with four different rigid and flexible ligandsi sd escribed. Transformations between the trefoil knots and the corre-sponding macrocycles can be induced by using concentration effects. Remarkably,t he hexanuclear trefoil knot 5 was shown to assemble further to provide rare examples of [12+ +1] heteronuclear double trefoil knots (5a/5 b/5 c/5 d) through coordination of the amide oxygen atoms to the secondary metal ions Na + /K + /Ca 2 + /Cd 2 + .T he synthetic results are supported by single-crystal XRD.[a] Dr.

Coordination-Directed Construction of Molecular Links

“…Only the signals corresponding to the tetranuclear macrocycle were observed in the NMR spectra of 56 until the concentration was decreased to 0.1 mM. Moreover, a mild and reversible topological transformation between the octanuclear Solomon link and a [6Rh + 2Ag] heterometallic trefoil knot , was realized by introducing and then removing silver­(I) ions.…”

Highly selective synthesis and near-infrared photothermal conversion of metalla-Borromean ring and [2]catenane assemblies

“…Changing the concentration or ratio of methanol to DMF has been shown to induce reversible supramolecular transformations between metalla [2]catenanes and the corresponding monorectangles. 53,54 This structural interconversion might be due to a weakening of the p-p stacking interactions by changing the concentration or the addition of DMF molecules. This inspired us to explore whether the transformation of metalla-Borromean rings could also occur, given the existence of multiple p-p stacking interactions between E5 and central unit of L1.…”

“…Fujita and coworkers reported a number of catenanes and a 7 1 knot through the coordination of Ag + ions and pyridine peptides, but their structural transformations were not studied. 34,35 The group of Jin has reported the selective construction of a series of intricate structures, such as molecular Borromean ring assemblies, [44][45][46][47][48][49][50][51] Solomon links, [52][53][54] 3 1 , 55 double trefoil, 56 and 4 1 knots, 57 and [2,3,4]catenanes. 24,58 The topological transformations between these structures were explored in detail through concentration-, solvent-and hostguest chemistry effects or via the chemical reactivity of the metal ions and organic ligands.…”

Backbone‐Directed Self‐Assembly of Interlocked Molecular Cyclic Metalla[3]Catenanes

“…Half‐sandwich metal‐containing precursors have been useful choices for the construction of interlocked structures . Combined with binuclear half‐sandwich organometallic clips and suitable pyridyl ligands, the selective formation of molecular Borromean rings, metalla[2]catenanes, metalla[3]catenanes, non‐catenane interlocked ring‐in‐ring motifs, knots, and Solomon links has been realized using coordination‐driven assembly. Nevertheless, interlocked cyclic metalla[3]catenanes comprising half‐sandwich organometallic fragments remains unknown.…”