Tris-N-alkylpyridinium-functionalised cyclotriguaiacylene hosts as axles in branched [4]pseudorotaxane formation

A series of [4]pseudorotaxanes composed of three-way axle threads based on the cyclotriguaiacylene family of crown-shaped cavitands and three threaded macrocyclic components has been achieved. These exploit the strong affinity for electron-poor alkyl-pyridinium units to reside within the electron-rich cavity of macrocycles, in this case dimethoxypillar[5]arene (DMP). The branched [4]pseudorotaxane= assemblies {(DMP)3∙L}3+,where L = N-alkylated derivatives of the host molecule (±)-tris-(isonicotinoyl)cyclotriguaiacylene, were characterised by NMR spectroscopy and mass spectrometry, and an energy-minimised structure of {(DMP)3∙(tris-(N-propyl-isonicotinoyl)cyclotriguaiacylene)}3+ was calculated. Crystal structures of N-ethyl-isonicotinoyl)cyclotriguaiacylene hexafluorophosphate and N-propyl-isonicotinoyl)cyclotriguaiacylene hexafluorophosphate each show ‘hand-shake’ self-inclusion motifs occurring between the individual cavitands

Metallo-cryptophane cages from cis-linked and trans-linked strategies

Trigonal bipyramidal metallo-cage species [Pd₃(dppp)₃(L)₂]∙6OTf (where dppp = bis(diphenylphosphino)propane, OTf = triflate and L is tris(iso-nicotinoyl)cyclotriguaiacylene (L1) or tris(fluoro-iso-nicotinoyl)cyclotriguaiacylene (FL1)) have been characterised in solution to exist predominantly as the anti-isomers. The crystal structure of [Pd₃(dppp)₃(FL1)₂]∙6OTf, however, was found to be the achiral syn-isomer. The complex [Pd₃Cl₃(L2)₂] (where L2 = tris(methylbenzimidazolyl)cyclotriguaiacylene) is a trans-linked M₃L₂ cage, observed by mass spectrometry and in the solid state as the anti-isomer. Ligand L2 also forms a 1:1 co-crystal with cyclotriguaiacylene

Lanthanide coordination polymers with pyridyl-N-oxide or carboxylate functionalised host ligands

The first examples of coordination polymers of hard-donor functionalised cyclotriveratrylene ligands with the lanthanide(iii) cations are reported, these include 1D 3-connected ladder structures and a 2D decorated kagome dual

Four new spin-crossover salts of [Fe(3-bpp)] (3-bpp = 2,6-bis[1H-pyrazol-3-yl]pyridine)

Four new salts of the well-known spin-crossover centre [Fe(3-bpp) ] are described: [Fe(3-bpp)][M(CN) ] (M = Ag, 1; M = Au, 2), [Fe(3-bpp)] [Au(SCN)] (3) and [Fe(3-bpp)][BPh ] (4) are reported. Monohydrate crystals of 1 and 2 are isostructural, and are better formulated as [Fe(3-bpp)] [M(CN)][M(CN)]·2H O (M = Ag or Au) with the mononuclear and trinuclear anion sites being disordered within each anion dyad. These groups are linked into a 2D network topology through N-H⋯X (X = N or O) hydrogen bonding between the cations and the cyanometallate anions, and the lattice water. In contrast, the complex cations in the solvate 4·2CHNO· (CH)O are completely encapsulated by phenyl groups from the BPh anions. Dried powder samples of 1-4 all exhibit very gradual thermal spin-state transitions centred at 198 ≤ T ≤ 291 K. ES mass spectrometry of 1-3 implies that extensive ligand exchange between the iron and coinage metal ions occurs in solution. Solid 1 and 2 are not emissive at room temperature upon irradiation in the UV

Encapsulation of sodium alkyl sulfates by the cyclotriveratrylene-based, [Pd6L8]12+ stella octangula cage

We have previously described a cyclotriveratrylene (CTV)-based complex, [Pd6L8]12+, that forms a highly symmetric stella octangula cage. Here we report on the ability of this system to host sodium salts of three alkyl sulfates; octyl (SOS), dodecyl (SDS) and tetradecyl (STS). 1H NMR chemical shift and diffusion coefficient measurements reveal that two molecules of alkyl sulfate reside in the cage, though rapid exchange between cage and bulk solvent is apparent. Host:guest association constants have been determined and support for the internalisation of the sulfates is available from 2D ROESY and NOESY data. © 2014 the Partner Organisations

An infinite chainmail of M6L6 metallacycles featuring multiple Borromean links

Borromean rings or links are topologically complex assemblies of three entangled rings where no two rings are interlinked in a chain-like catenane, yet the three rings cannot be separated. We report here a metallacycle complex whose crystalline network forms the first example of a new class of entanglement. The complex is formed from the self-assembly of CuBr2 with the cyclotriveratrylene-scaffold ligand (±)-tris(iso-nicotinoyl)cyclotriguaiacylene. Individual metallacycles are interwoven into a two-dimensional chainmail network where each metallacycle exhibits multiple Borromean-ring-like associations with its neighbours. This only occurs in the solid state, and also represents the first example of a crystalline infinite chainmail two-dimensional network. Crystals of the complex were twinned and have an unusual hollow tubular morphology that is likely to result from a localized dissolution-recrystallization proces