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This paper describes the syntheses of several functionalized dihydropyrene (DHP) molecular switches with different substitution patterns. Regioselective nucleophilic alkylation of a 5-substituted dimethyl isophthalate allowed the development of a workable synthetic protocol for the preparation of 2,7-alkyne-functionalized DHPs. Synthesis of DHPs with surface-anchoring groups in the 2,7- and 4,9-positions is described. The molecular structures of several intermediates and DHPs were elucidated by X-ray single-crystal diffraction. Molecular properties and switching capabilities of both types of DHPs were assessed by light irradiation experiments, spectroelectrochemistry, and cyclic voltammetry. Spectroelectrochemistry, in combination with density functional theory (DFT) calculations, shows reversible electrochemical switching from the DHP forms to the cyclophanediene (CPD) forms. Charge-transport behavior was assessed in single-molecule scanning tunneling microscope (STM) break junctions, combined with density functional theory-based quantum transport calculations. All DHPs with surface-contacting groups form stable molecular junctions. Experiments show that the molecular conductance depends on the substitution pattern of the DHP motif. The conductance was found to decrease with increasing applied bias.

Diorganotin(IV) derivatives of 4‐acyl‐5‐pyrazolones Q2SnR2[HQ = 3‐methyl‐1‐phenyl‐4‐R‐5‐pyrazolone: HQnPe, R = neopentylcarbonyl; HQiPr, R = isopropylcarbonyl; HQtBu, R = tert‐butylcarbonyl; HQCy, R = cyclohexylcarbonyl; HQCp, R = cyclopentylcarbonyl; HQEtCp, R = (ethylcyclopentyl)carbonyl] have been synthesized and characterized spectroscopically (IR, far‐IR, 1H, 13C and 119Sn NMR) and structurally (X‐ray). Steric bulkiness in the acyl fragment of HQtBuinduces partial dissociation in solution of (QtBu)2SnMe2, which exists as an equilibrium mixture of six‐ and five‐coordinate tin species. Single‐crystal X‐ray structure determinations of several representative complexes are presented. Whereas the dialkyltin(IV) complexes are always trans‐octahedral, a diphenyltin(IV) derivative exists in the solid state that has the two phenyl groups in a cisarrangement. DMol3 and CASTEP DFT studies of this unprecedented cis, and the corresponding transconfigurations, show the former to be slightly more stable, in agreement with the diffraction study. Solid‐state 119Sn cross‐polarization magic‐angle spinning NMR spectroscopic data show that the isotropic chemical shifts (δiso,mas) and chemical‐shift anisotropies/spans (Δδ/Ω) that characterize the diphenyl(IV) derivatives are markedly removed from values measured for the corresponding dimethyl and di‐n‐butyl derivatives, thereby adding further evidence for a stable cisconfiguration in the diphenyl(IV) systems. This is supported by GIPAW DFT calculation of the 119Sn isotropic shifts and chemical‐shift anisotropies/spans from fully relaxed structures by using the CASTEP code, which provides a direct link between the cisdiphenyl(IV) arrangement and the reported differences in the 119Sn NMR spectroscopic parameters.

Extension of previous work on the lanthanideIII ion complexes of ptertbutyltetrathiacalix[4]arene has led to a variety of structurally characterised species containing oxo, hydroxo and aqualigands presumably derived from water present in the preparative medium, along with the thiacalixarene in various stages of deprotonation. The overall stoichiometry of some species is remarkably complicated due to the presence of simple anions and multiple solvents. Simplest is the binuclear complex [μH2OLnOdmf22HL·dmf2]·nS dmf = dimethylformamide [1Ln, Ln = Sm nS = 2dmf, Eu nS = 1.5dmf·2MeCN], also the bestdefined of all the arrays studied. The heaviest lanthanides give trinuclear LnOH3·2LnLH·xdmf·yH2O 2Ln, Ln = Yb, Lu, while both oxo and hydroxo species are isolable with Eu: trinuclear Eu3OLLHLH4·13dmf 3 and tetranuclear Eu4OOH2LLH22LH4·12dmf 9, both somewhat atypical species containing uncoordinated thiacalixarene molecules within the lattice. Anion NO3, ClO4 coordination, as in the tri and tetranuclear species, 4–6Ln, 9, 10Ln, 11Ln, 12, seems especially favoured for the lighter lanthanides. In these arrays, the Ln3and Ln4aggregates are triangular or quasisquareplanar, except for Gd4O2LH24·2H2O·2MeOH·2dmf·3.375CH2Cl212, where there is a Zdisposition. Most common is an Ln3O core, which spans the gamut of Ln in three sets of crystal forms with cells of similar dimensions: for Ln = La...Nd, Ln3OHNO34LH22·4.5dmf 5Ln space group C2m, and Sm...Lu, Ln3ONO3LH2·4H2O·2dmso·2MeCN·3py 6Ln space group P21n, conformity with crystallographic symmetryentails disorder of the Ln atoms; in a further form of lowersymmetry Pn, pyHLn3ONO32LH2·2MeCN·xH2O·ydmso·1.5py·MeOH 7Ln, Ln = La, Ce, with no imposed crystallographic symmetry, some disorder persists, but none is found in the crystallographically unrelated form of 8Pr, Pr3ONO3LH2·16H2O·2MeCN·5py. Ln4OHNO33L2·8dmf·2dmso·3H2O 10Ln, Ln = Pr...Gd, previously defined for Nd has a squareplanar Ln4O array sandwiched between a pair of L ligands, with a similar form found for Ln4OClO42L2·xdmf·yH2O 11Ln, Ln = La...Nd.

In toluene fullerene C70forms 2:1 complexes with p‐benzylcalix[5]arene (1) and p‐phenylcalix[5]arene (2), [C70⊂12]⋅6 (C7H8) and [C70⊂22]⋅7 (C7H8). The fullerene molecules are completely shrouded by two calix[5]arenes in addition to terminal benzyl groups from other supermolecules, [C70⊂12], and solvent. Within the capsule‐like supermolecules the calixarenes have distinctly different arrangements relative to the principal axis of the fullerene; for [C70⊂12]⋅6 (C7H8) the oxygen planes of the two calixarenes are skewed by 37.0 and 47.5°, whereas in [C70⊂22]⋅7 (C7H8) the principal axes of the fullerene and the two encapsulating calixarenes are more closely aligned with the corresponding angles at 9.7 and 8.6°, and features a pentaphenyl inter‐calixarene embrace. The Hirshfeld surfaces of these two complexes have been investigated for a detailed understanding of the orientation and nature of interactions of C70with the cavitand‐type molecules and toluene.

p-But-calix[5]arene forms crystalline inclusion complexes with o- and m-carboranes in toluene or dichloromethane–hexane, but not with the p-isomer, the extended structures being based on 1 : 1 host–guest supermolecules, with the p-But-substituents creating a snug fit for o- and m-carborane; p-carborane forms a highly hexane soluble complex, induced by grinding, which crystallizes as fibres. Solution phase studies showed the presence of a 1 : 1 host–guest stoichiometry with all three isomeric carboranes as determined from Job plots. The association constants for the o- and m-carborane complexes are 6.4 ± 0.3 M−1 and 3.8 ± 0.1 M−1 respectively, whereas the p-isomer is only weakly associated. Competition experiments involving all three isomers show rapid exchange on the NMR time scale, and no selectivity in solution is evident. Selective association involving the o- and m-isomers in the solid state is therefore remarkable, and it is a manifestation of crystal packing forces which embodies the differences in dipole moments of the carboranes.

A new paradigm for the synthesis of 4′-pyridyl terpyridines using polyethyleneglycol (PEG) as a benign reaction medium is described, with the compounds readily accessible in high purity in ca.4 hours using a ‘one pot’ procedure. This method requires no product purification and affords the desired compounds in reasonable yield without the formation of unwanted side products.

The novel 2,7-bis((TIPS)ethynyl)-10b,10c-diethyldihydropyrene photochrome (TIPS = triisopropylsilyl) was observed to undergo thermal rearrangement to 2,7-bis(TIPS-ethynyl)-pyrene in the solid state. The transformation proceeds stepwise with ethyl groups “dancing” out of the dihydropyrene core toward the periphery of the polycyclic framework. The formation of two regioisomers occurs initially and is followed by two progressive de-ethylations to give a pyrene. This transformation occurs in the solid crystalline state and represents a unique example of a single-crystal-to-single-crystal (SC-SC) transformation involving C–C bond cleavages with hydrocarbon fragments escaping the ordered crystalline structure. Detailed characterizations of the transformation by in situ temperature-dependent X-ray single-crystal diffraction supported by thermal analysis, HPLC-mass spectrometry experiments, NMR spectroscopy, and theoretical calculations, are reported.

Reaction of equimolar amounts of sodium para-sulfonato-calix4arene, tetraphenylphosphonium chloride and ytterbium chloride in water results in the formation of a mineral clay-like structure, where the hydrophobic tetraphenylphosphonium cations interpose a bilayer arrangement based on a 2D coordination polymer of calix4arene5−NaYb3.

The crystal structure of the title compound, [ReCl4(C8H10N2)2], has been determined by X‐ray diffraction at 11 K and by neutron diffraction at 20 K. The accurate and extensive data sets lead to more precise determinations than are available from earlier work. The agreement in atomic positional and displacement parameters at these very low temperatures is good. The results will facilitate re‐examination of the magnetic structure of the complex. The Re atom lies on a special position and the molecule has twofold crystallographic symmetry.

Precise X‐ray determinations of the crystal structure of the 1:2 complex of N‐ethyl‐N‐methyl­morpholinium and 7,7,8,8‐tetra­cyano‐p‐quinodi­methanide, abbreviated as MEM–TCNQ or MEM(TCNQ)2(C7H16NO+·2C12H4N40.5−), have been performed at 293 and at 10 K. Evidence for the expected spin‐Peierls transition at 19 K is not found, and this may follow from radiation damage to the crystal or from insufficient equipment sensitivity.

The crystal structure of Na2Fe(CN)5(NO)·2D2O, disodium penta­cyano­nitro­syl­ferrate(III) bis­(dideuterium oxide), has been determined by X‐ray diffraction at 11 and 293 K, and by neutron diffraction at 15 K. The accurate and extensive data sets lead to more precise determinations than are available from earlier work. The agreement in atomic positional and displacement parameters between the determinations at low temperature is very good.