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The sulfur-bridged compound 7α,15α-dibromo-6,7,14,15-tetrahydro-6α,14α-thiacycloocta[1,2-b:5,6-b′]diquinoline (10) yields an apohost crystal form plus a series of six lattice inclusion compounds. The diverse range of their X-ray crystal forms is described, and the structures are compared in crystal engineering terms. Compound 10 exhibits none of the anomalous properties shown earlier by its oxygen-bridged and nor-bromo cousins. Further, it demonstrates inclusion capabilities considerably superior to its methano-bridged analogue. Although the sulfur atom does not appear to be actively driving inclusion host behavior, closer analysis reveals that it is always involved. Multiple sulfur interactions are present in all these clathrate structures, most commonly involving bifurcated H···S···H motifs.

The very simple alicyclic compounds 3,7-dimethylbicyclo[3.3.0]octane-endo-3,endo-7-diol 3 and 2,6-dimethylbicyclo[3.3.0]octane-endo-2,endo-6-diol 5 were selected for study in the knowledge that these are awkwardly shaped molecules that are likely to pack in the solid state with some difficulty. The design philosophy behind the choice of these particular test molecules is explained. We expected that these isomeric diols would probably yield more than one crystal form if crystallized from a range of different solvents. Dialcohol 3 was found to give three (benzene clathrate, hemihydrate, and hydrate), and dialcohol 5 to give two (racemic and kryptoracemate/false conglomerate), crystal forms. The X-ray structures of these five very different crystalline solids (formed by two very similar model compounds) are described and contrasted. Our findings demonstrate that awkward molecules can be identified and indicate that the formation of alternative crystal forms is likely to be a comparatively frequent occurrence...

The sulfur-bridged compound 6,7,14,15-tetrahydro-6,14-thiacycloocta[1,2-b:5,6-b′]diquinoline (11) yields a solvent-free crystal form but also produces lattice inclusion compounds containing chloroform, water, and methanol. This latter behavior is in marked contrast to the noninclusion characteristics shown by its corresponding oxygen- and methano-bridged analogues. X-ray structures of the three different crystal types formed by 11 reveal that all contain a two-molecule repeat unit in which the S atom of the first is located within the V-shaped cleft of the second. This assembly is reminiscent of a ball and socket joint, and the adoption of this motif is the root cause of the unexpected solid-state inclusion properties shown by 11.

The dibromodiquinoline derivative 2 yields crystalline lattice inclusion compounds with a wide range of guest molecules. The solvent-free crystal structure is also formed. In all these, pairs of dibromodiquinoline molecules form centrosymmetric brick-like dimers by means of three different aromatic edge−face (EF) interactions. The resultant (EF)6 building blocks, which are virtually identical across the series of 13 crystal structures described, act as tectons that pack into layers. Guest molecules occupy interlayer spaces near the corners of the tectons, with the host−guest attractions acting as molecular mortar and allowing variation of the inclusion structures dependent on guest size, shape, and functionality. The apohost crystal structure demonstrates that guest-free packing of these molecular bricks (analogous to the dry stone construction method) is also favorable. The molecular substitution of a dibromodiquinoline unit required to ensure dimeric (EF)6 tecton formation is explained.

Reaction of the dipyridyl-substituted tetrapropoxycalix[4]arene 1 with palladium(II) chloride yields the unusual metallomacrocycle 2. The calixarene substituents of 1 and 2 show major conformational differences from X-ray determinations, and molecule 2 crystallizes as the inclusion compound (2).(CHCl3)x (x ∼ 7) in space group R3. Three repeating layers stack to form parallel tubes that contain the disordered guests. Intruding host propoxy groups constrict these tubes at every third layer, and the formation of this tubulate structure is explained in terms of the host wheel and axle topology.

Chloro-substituted diquinoline dibromide 6 is a versatile host molecule that includes guest molecules of different functionality in several different ways. The crystal structures of 6 and its lattice inclusion compounds with carbon disulfide, dichloromethane, acetone, chloroform, benzene, and toluene are reported and analyzed in crystal engineering terms. Also described is the quinolinium inclusion compound (11)·(acetophenone). The inclusion properties of 6, and the ways that it achieves these, are very different from those of its non-chlorinated parent, 4. Different types of aromatic interfacial packing are discussed. There is far greater dependence on these types of interactions and a complete absence of the aromatic edge−edge C−H···N dimer motif in the crystal structures of 6.

Dibromodiquinoline 8 forms lattice inclusion compounds when crystallized from solvents such as dichloromethane, tetrahydrofuran, chloroform, and benzene. The crystal structures of these compounds are described in crystal engineering terms, and are also compared with the solvent-free crystal structures of 8 and its nonbrominated precursor 6. Aromatic edge−edge double C−H···N interactions play a crucial role in all six solids. These comprise both cyclic hydrogen-bonded dimer and bifurcated C−H···N···H−C types. A diverse range of structurally different double C−H···N motifs is encountered in these, and closely related, compounds.

The tetrabromodiquinoline 2, and its tetraiodo counterpart 3, are members of the new tetrahalo aryl host family. They form lattice inclusion compounds when crystallized from many organic liquids, and the X-ray crystal structures of five such compounds are reported and analyzed in crystal engineering terms. Host molecules assemble into parallel staircases by means of aryl offset face-face and halogen-halogen interactions both within, and between, the staircases. The guests are situated in parallel interstitial channels. Variation of the type of included guest can result in significant changes to the construction and symmetry of the host staircase assemblies.

The diols 7-11 have been synthesized, and their X-ray crystal structures determined, to learn how to influence and control lattice hydroxy group hydrogen bonding using crystal engineering ideas. To obtain new lattice inclusion hosts precise structural rules can be defined which enable the necessary supramolecular interactions to be duplicated. In this manner the helical tubuland 10 and ellipsoidal clathrate 11 hosts were obtained for the first time and their chloroform inclusion compounds characterized. New synthetic routes were utilized to obtain the bicyclo[3.3.2]decane and 9-thiatricyclo[4.3.1.1(3,8)]undecane frameworks present in these compounds. The solid-state conformations of bicyclo[3.3.2]decane derivatives 9 and 10 are compared with prior predictions and studies made on this uncommon ring system.

The crystal structures of (Ph3PCl)2[Cu3Cl8] (1) (triclinic, space group P1, a = 9.480(6) A, b = 10.243(8) A, c = 11.232(6) A, α = 86.76(4)°, β = 66.62(5)°, γ = 83.92(4)°, Z = 1) and (Ph3PMe)2[Cu3Br8] (2) (triclinic, space group P1, a = 9.795(4) A, b = 10.472(4) A, c = 11.392(4) A, α = 86.67(3)°, β = 66.67(3)°, γ = 83.14(3)°, Z = 1), reported here, demonstrate a new supramolecular motif for cations of the type Ph3PY+ where Y is CH3 or Cl. The crystals contain columns of cations propagated by alternating 6-fold phenyl embraces (6PE) and pseudo-6PE: the pseudo-6PE described here contains four phenyl rings and two hetero groups (Cl or CH3), and is symbolized as 4P2Y. The zigzag sequence of cations engaged in ···6P···4P2Y···6P···4P2Y··· is similar to the zigzag chain of infinite 6-fold phenyl embraces (ZZI6PE) frequently adopted by Ph4P+ cations in crystals. One-dimensionally nonmolecular anion chains with repeat unit [Cu3X8] run parallel to and between the columns of cations. The coordination geometry in t...

A family of 4-substituted-1-cubanecarboxylic acids have been synthesized and their X-ray crystal structures analyzed. The rare syn-anti O−H···O catemer 6 is a recurring pattern in this series of compounds. Catemer 6 is observed in the crystal structures of 4-chloro-1-cubanecarboxylic acid (10), 4-bromo-1-cubanecarboxylic acid (11), 4-iodo-1-cubanecarboxylic acid (12), and 4-(methoxycarbonyl)-1-cubanecarboxylic acid (13). The ready occurrence of catemer 6 in this family is ascribed to its stabilization by auxiliary C−H···O hydrogen bonds formed by the relatively acidic cubyl C−H groups. The frequency of occurrence of 6 also facilitates its definition as a useful supramolecular synthon. As is true in many catemers, the formation of 6 is sensitive to steric factors. Therefore, the robustness of this synthon may be assessed by analyzing the crystal structures of molecules wherein the 4-substituent is too small (R = H, 14), too large (R = Ph, 15), or has a specific hydrogen bonding preference of its own (R = C...

A series of compounds (1−8) has been prepared in which a 1,4-dimethoxynaphthalene (DMN) group and either two thiol groups or a disulfide moiety are attached to the respective termini of rigid “norbornylogous” hydrocarbon bridges, 3, 5, 7, 9, and 13 bonds in length. Each of the molecules forms an adsorbate monolayer when its CH2Cl2 solutions are exposed to etched gold. Chemically reversible one-electron oxidation of the DMN group is observed in CH2Cl2 or CH3CN at potentials of 0.54−0.67 V vs ferrocene. Repeated potential cycling demonstates less monolayer degradation (a) in CH2Cl2 compared to CH3CN and (b) at subambient temperatures. Fast cyclic voltammetry experiments establish that the electron-transfer rates between the naphthalene group and the electrode surface are very fast (>103 s-1).

Any organic crystal structure can be simplified to a network wherein the molecules are the nodes and the supramolecular synthons are the node connections. This approach to crystal engineering is illustrated in this paper with reference to organic structures based on the diamond network. By introducing N· · ·Br synthons into this network, a 2-fold-catenated structure is obtained for the 1:1 complex between hexamethylenetetramine (HMT) and CBr4. The use of C−H· · ·N mediated synthons in the same network results in the 1:2 complex of 1,3,5,7-tetrabromoadamantane (AdBr4) with HMT. Further structural flexibility is achieved by the interchange of molecular and supramolecular synthons. Accordingly, the diamond-based crystal structures of tetrakis-(4-bromophenyl)methane and the 1:1 molecular complex of tetraphenylmethane and CBr4 are very similar. This near-identity arises because of the structural equivalence of the CBr4 molecular synthon and the Br4 supramolecular synthon and the ability of the CBr4 molecule to...