An octanuclear [Co(II)2-Co(III)2]2 interlocked grid--example of an inorganic [2]catenane

An oxalic dihydrazide based flexible polydentate amidrazone ligand undergoes spontaneous [2 x 2] grid assembly, followed by partial disassembly, and then reassembly in the presence of Co(NO3)2.6H2O and NH4(NCS) to form a unique octanuclear [Co(II)2-Co(III)2]2 interlocked, single braided 4 + 4 [2]catenane.     

A circular tris[2]catenane from molecular 'figure-of-eight'

A 'figure-of-eight'-shaped molecule with Pd(ii) at the node was self-assembled into an unprecedented circular tris[2]catenane via reversible double catenation at both loops of the 'figure-of-eight' molecule.     

Half-rotation in a [2]catenane via interconvertible Pd(II) coordination modes

Reaction of a [2]catenane with Pd(OAc)2 binds both macrocycles to the metal, locking them in position; treatment with PdCl2, however, results in coordination of only one ring, producing a half-turn in the relative orientation of the [2]catenane components in both solution and the solid state.     

A reverse donor-acceptor bistable [2]catenane

A [2]catenane, composed of a pi-electron-rich bis-1,5-dioxynaphthalene[38]crown10 (BDNP38C10) ring, mechanically interlocked with a large macrocycle containing two disubstituted tetraarylmethane "speed bumps" and two different pi-electron-deficient units--namely, naphthalene dimide (NpI) and bipyridinium (BIPY(2+)) units--has been synthesized from a [2]rotaxane, containing the former recognition unit, after performing two sequential Cu(I)-catalyzed azide-alkyne cycloadditions with a linker containing the latter recognition unit. The product, which exists as a single co-conformer, wherein the BDNP38C10 ring encircles the NpI unit, undergoes equilibration to give approximately equal amounts of the other co-conformer in which the BDNP38C10 ring encircles the BIPY(2+) unit.     

A Bistable Poly[2]catenane Forms Nanosuperstructures

Side‐chain poly[2]catenanes at the click of a switch! A bistable side‐chain poly[2]catenane has been synthesized and found to form hierarchical self‐assembled hollow superstructures of nanoscale dimensions in solution. Molecular electromechanical switching (see picture) of the material is demonstrated, and the ground‐state equilibrium thermodynamics and switching kinetics are examined as the initial steps towards processible molecular‐based electronic devices and nanoelectromechanical systems.

     

Versatile formation of [2]catenane and [2]pseudorotaxane structures; threading and noncovalent stoppering by a self-assembled macrocycle

A self-assembled dimeric macrocycle between 4,4'-bis(4-pyridylmethoxy)biphenyl (L) and (en)Pd(NO(3))(2) was constructed, and its interactions with cyclodextrins of different cavity size resulted in the formation of [2]catenane and [2]pseudorotaxane systems, respectively. The structures were identified by 1D and 2D NMR spectroscopy and cold spray ionization mass (CSI-MS) spectrometry.     

Anion-templated assembly of a [2]catenane

The first example of a [2]catenane structure to be synthesized using anion templation is described. The nature of the anion template is demonstrated to be crucial to the assembly process, with only chloride anion producing the [2]catenane in acceptable yield. Anion binding studies reveal a dramatic catenation effect on anion selectivity properties as compared to a noncatenated acyclic receptor.     

A new infinite inorganic [n]catenane from silver and bis(2-methylimidazolyl)methane ligand

A new type of 1D infinite inorganic [n]catenane framework was self-assembled by silver nitrate and bis(2-methylimidazolyl)methane, while a comparatively one-dimensional zigzag cationic chain was generated by AgNO(3) and bis(imidazol-1-yl)methane.     

Construction of a hetero pseudo[2]rota[2]catenane

A novel ammonium template containing three ammonium sites was synthesized. Two ammoniums located on the linear component served as template for cucurbit[6]uril to form the CB-based pseudo[2]rotacane while another one located on the macrocyclic component played a role of template for clipping reaction. As a result of a ‘‘threading-followed-by-clipping' approach, a novel hetero pseudo[2]rota[2]catenane was successfully constructed.     

A [2]catenane constructed around a rhodium(III) center used as a template

Rhodium(III) has been used as a templating metal center for building a [2]catenane. In the first stage, a Rh(phen)(2) motif has been incorporated into a large ring. Subsequently, a 2,2'-bipyridine derivative has been threaded through the ring, this process being driven by coordination of the chelate to the Rh(III) center. The formation of the second ring has been performed using the ring-closing metathesis approach. Contrary to the other catenanes synthesized around transition metals, the second ring is formed at the rear of the coordination unit which it contains, by cyclizing two flexible end-functionalized fragments attached at the 4 and 4' positions of the 2,2'-bipyridine chelate.