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Crystal structures of a series of tripodal triethylbenzene-based compounds, bearing phenoxy groups substituted by one to three halogen atoms, are characterized by the presence of inversion-symmetric dimers.

In the title 1:1 co-crystal, [Cu(C24H24N8O6)]·C11H11N3O4, each of the crystal components forms undulating layers which stack alternately along the b-axis direction. Molecules of the CuII complex are connected via C—H...O hydrogen bonds involving the nitro and keto oxygen atoms, thus forming supramolecular networks. Molecules of the arylhydrazone component are linked by C—H...O interactions into zigzag strands showing no interstrand association.

The title compound shows a mol­ecular framework with the di­phenyl­ethyne unit slightly deviating from planarity and the l-alanine moieties adopting a distorted helical conformation. The crystal structure features a two-dimensional network supported by N—H⋯O and C—H⋯O hydrogen bonding., The di­phenyl­ethyne unit of the title mol­ecule, C24H24N2O6, deviates slightly from planarity. The l-alanine moieties adopt distorted helical conformations of opposite winding direction. Infinite ribbons of N—H⋯O=C-connected mol­ecules represent the basic supra­molecular entities of the crystal structure. These aggregates are linked by C—H⋯O hydrogen bonds involving the oxygen atoms of the methyl carboxyl­ate units. The crystal studied was refined as an inversion twin.

Correction for ‘Binding modes of methyl α-d-glucopyranoside to an artificial receptor in crystalline complexes’ by Linda Köhler et al., RSC Adv., 2021, 11, 22221–22229. DOI: 10.1039/d1ra03390e.

The 5-iodo- and 5-ethynyl-substituted dimethyl isophthalates show mol­ecular frameworks with methyl carboxyl­ate moieties being tilted or perfectly planar with respect to the benzene ring, respectively. Crystal structures feature a three- or two-dimensional supra­molecular aggregation in the iodo and ethynyl derivatives, respectively, supported by C—H⋯I and C—H⋯O hydrogen bonding as well as I⋯O and π–π inter­actions., In dimethyl 5-iodo­isophthalate, C10H9IO4, (I), the planes through the methyl carboxyl­ate moieties are tilted with respect to the benzene ring, whereas the mol­ecular framework of dimethyl 5-ethynylisophthalate, C12H10O4, (II), is perfectly planar. The crystal structure of (I) is stabilized by a three-dimensional supra­molecular network comprising C—H⋯O=C hydrogen bonds, as well as I⋯O=C inter­actions. In the crystal of (II), the mol­ecules are connected via C—Hethyn­yl⋯O=C hydrogen bonds to infinite strands. Moreover, π–π arene stacking inter­actions connect the mol­ecular chains into two-dimensional supra­molecular aggregates.

The syntheses and crystal structures ofN-(7-bromomethyl-1,8-naphthyridin-2-yl)acetamide dioxane hemisolvate, C11H10BrN3O·0.5C4H8O2, (I), and bis[N-(7-dibromomethyl-1,8-naphthyridin-2-yl)acetamide] dioxane hemisolvate, 2C11H9Br2N3O·0.5C4H8O2, (II), are described. The molecules adopt a conformation with the N—H hydrogen pointing towards the lone electron pair of the adjacent naphthyridine N atom. The crystals of (I) are stabilized by a three-dimensional supramolecular network comprising N—H...N, C—H...N and C—H...O hydrogen bonds, as well as C—Br...π halogen bonds. The crystals of compound (II) are stabilized by a three-dimensional supramolecular network comprising N—H...N, C—H...N and C—H...O hydrogen bonds, as well as C—H...π contacts and C—Br...π halogen bonds. The structure of the substituent attached in the 7-position of the naphthyridine skeleton has a fundamental influence on the pattern of intermolecular noncovalent bonding. While the Br atom of (I) participates in weak C—Br...Oguestand C—Br...π contacts, the Br atoms of compound (II) are involved in host–host interactionsviaC—Br...O=C, C—Br...N and C—Br...π bonding.

X-ray analyses of a series of benzene-based tripodal molecules 1–9, bearing either bromo-substituted pyrazole groups or analogues lacking the bromo substituents, provide interesting insights into the molecular recognition phenomena and also give information about the different conformations which adopt the tripodal molecules in the solvent-free crystals and in solvates. The crystal packings are characterized by the presence of C–H⋯O, C–H⋯N, C–H⋯Br and C–H⋯Cl hydrogen bonds as well as C–Br⋯N, C–Br⋯Br, C–Br⋯Cl and C–Br⋯π halogen bonds. The conformations observed in the case of the triethyl- and trimethoxybenzene-based compounds can be defined as ab'ab'ab', ab'ab'ba', ab'ab'bb', ab'aa'ba', ab'aa'bb', aa'ab'ba' and aa'aa'aa' with the pyrazole-bearing arms arranged either in an aaa or an aab fashion.

A series of azines featuring differently halogen and protic group substituted pyridine, pyrimidine and pyridazine compounds have been synthesized and studied in terms of their crystal structures in order to develop a better understanding of the links between structural conditions and molecular packing behavior. Complemented by the structure results of related compounds known from the literature, intermolecular contact relationships connected to the present substance types were found, having potential use in future crystal engineering of similar compounds. This primarily involves the formation of N⋯I contacts aside from specific halogen⋯halogen and hydrogen bond type interactions.

Crystal structures of two 4-substituted derivatives of 2-acetyl­phenol are discussed comparatively with reference to modes of hydrogen bonding., In the title compounds, C10H8O2, (I), and C13H14O3, (II), the 2-acetyl-4-ethynylphenol unit displays a planar geometry, which is stabilized by an intra­molecular O—H⋯O hydrogen bond. The crystal structure of (I) is constructed of infinite strands, along [101], of C—H⋯O=C hydrogen-bonded mol­ecules, which in turn are linked by C—H⋯π inter­actions. In the crystal of (II), which crystallized with three independent mol­ecules per asymmetric unit, the non-polar parts of the mol­ecules form hydro­phobic layered domains, parallel to (10-1), which are separated by the polar groups. While the 2-acetyl­phenol part of the mol­ecules are involved in O—H⋯O=C hydrogen bonding, the ternary OH groups creates a cyclic pattern of O—H⋯O hydrogen bonds.

Four new host compounds of dumbbell shape featuring bulky 2,3,4,5-tetraphenylcyclopenta-2,4-dien-1-ol moieties attached to both ends of a linear spacer element of different lengths comprising both 1,4-phenylene and ethynylene subunits are synthesized and corresponding crystal inclusions involving DMSO, DMF, MeCN, and THF as guest solvents (seven examples of inclusion compounds) are isolated. X-ray structural analysis shows the formation of 1:2 host/guest entities being a basic supramolecular motif of the crystal inclusions. Nevertheless, additional solvent molecules seem to be necessary for stabilization of the crystal structure in most cases of the inclusion species indicating the occurrence of unusually high stoichiometric ratios of included solvent as a specific characteristic of the new type of host molecule.

A new polymorph of di(thio­phen-3-yl) ketone differing from the previous structure by the mol­ecular assembly is reported and comparatively discussed., The crystal structure of the title compound, C9H6OS2, represents a new polymorph. The crystal structure was solved in the ortho­rhom­bic space group Pbcn with one half of the mol­ecule in the asymmetric unit. The thio­phene rings are perfectly planar and twisted with respect to each other, showing the mol­ecule to be in an S,O-trans/S,O-trans conformation. In the crystal, C—H⋯O hydrogen bonds connect the mol­ecules into layers extending parallel to the ab plane. The crystal structure also features π–π inter­actions.

The ethynyl­pyrimidine moiety displays an almost planar geometry. In the crystal, mol­ecules are linked by O—H⋯N and C—Hpyrimidine⋯O hydrogen bonds, forming a three-dimensional supra­molecular architecture., In the title compound, C9H9ClN2O, the ethynyl­pyrimidine moiety displays an almost planar geometry. In the crystal, mol­ecules are linked by O—H⋯N and C—Hpyrimidine⋯O hydrogen bonds, forming a three-dimensional supra­molecular architecture.

In the crystal structure of 2,2′′-bis­(2,7-di­chloro-9-hy­droxy-9-fluoren­yl)-1,1′:4′,1′′-terphenyl as the tris­(tri­ethyl­amine) solvate, the diol host mol­ecule possesses a ‘folded’ mol­ecular conformation with inversion symmetry. Two of the three solvent mol­ecules form O—H⋯N hydrogen bonds and the third one forms C—H⋯N hydrogen bonds with the host compound., In the title solvate, C44H26Cl4O2·3C6H15N, the asymmetric part of the unit cell comprises two halves of the diol mol­ecules, 2,2′′-bis­(2,7-di­chloro-9-hy­droxy-9H-fluoren-9-yl)-1,1′:4′,1′′-terphenyl, and three mol­ecules of tri­ethyl­amine, i. e. the diol mol­ecules are located on crystallographic symmetry centres. Two of the solvent mol­ecules are disordered over two positions [occupancy ratios of 0.567 (3):0.433 (3) and 0.503 (3):0.497 (3)]. In the diol mol­ecules, the outer rings of the 1,1′:4′,1′′-terphenyl elements are twisted with reference to their central arene ring and the mean planes of the fluorenyl moieties are inclined with respect to the terphenyl ring to which they are connected, the latter making dihedral angles of 82.05 (8) and 82.28 (8)°. The presence of two 9-fluoren-9-ol units attached at positions 2 and 2′′ of the terphenyl moiety induces a ‘folded’ geometry which is stabilized by intra­molecular C—H⋯O hydrogen bonds and π–π stacking inter­actions, the latter formed between the fluorenyl units and the central ring of the terphenyl unit [centroid–centroid distances = 3.559 (1) and 3.562 (1) Å]. The crystal is composed of 1:2 complex units, in which the solvent mol­ecules are associated with the diol mol­ecules via O—H⋯N hydrogen bonds, while the remaining solvent mol­ecule is linked to the host by a C—H⋯N hydrogen bond. The given pattern of inter­molecular inter­actions results in formation of chain structures extending along [010].

Sixteen new bisurea compounds incorporating versatile proteinogenic amino acids as well as nipecotic acid have been synthesized via addition reaction to aryl diisocyanates. The products were analytically characterized and their ability for anion recognition was studied by UV/Vis spectroscopy. In the presence of fluoride, acetate or dihydrogenphosphate ions, hyperchromic and bathochromic peak shifts were determined. By way of contrast, bromide, iodide, or hydrogensulfate ions cause no significant change of absorbance. The special effect of heterocyclic derivatives was explained by molecular modeling calculations. In addition, the crystal structure of the byproduct dimethyl N,N′-(1,4-phenylene)dicarbamate is discussed.

Four trityl compounds differing both in the functional group (OH, OMe, NH2) at the specific trityl carbon and a para substituent, being bromine or phenyl at one of the phenyl groups, have been prepared and structurally studied by means of single crystal X-ray diffraction and making use of Hirshfeld surface analysis. Compared to the structures of corresponding prototypes and analogues, specific interaction modes and packing motifs including cluster aggregates as well as non-cluster type structures depending on the substitution and involving polymorphism were found, opening potential trend prediction with reference to crystal engineering being useful in this compound class.

Crystalline inclusion compounds of diol hosts 1 and 2 typical of a basic 2,2″-[1,1′:4′,4″]-terphenyl moiety with two attached 9-fluorenol or tert-butyl-substituted 9-fluorenol units and a variety of aprotic guest molecules have been prepared and studied with reference to their crystal structures. Common and differing structural features among one another and including previously described host–guest complexes of 1 and 2 with protic instead of aprotic guest species are distinguished, indicating potential uses in promising supramolecular inclusion formation and underscoring solvent inclusion.

A rather easily structured permethylated dinitro calix[4]arene was found to exhibit large, stable and rigid channels in the solid state. These were obtained as guest free as well as solvent filled species and proved to reversibly adsorb selected organic solvents. Combined use of QMB measurements and X-ray powder diffraction revealed the predominantly reversible interaction of dichloromethane vapour with the channel structure as well as the integrity of the nanopores during adsorption and desorption. Examination of the flexible host component by NMR spectroscopy revealed a mixture of interchanging conformational isomers which could explain the high sensitivity of the crystallization process from the employed solvents.

The diol host compound 2 featuring a structure with two 9-fluorenol moieties attached in 3,3′-position to a biphenyl core unit has been synthesized and is shown to form crystalline inclusion complexes with organic guest molecules. Aside from the single-crystal X-ray structures of unsolvated 2 in two polymorphous forms (2A, 2B), structures of five inclusion compounds with 1,4-dioxane (2a), DMSO (2b), diethylamine (2c), acetic acid (2d), and ethyl acetate (2e) are described and comparatively discussed in the interaction behavior including corresponding host compounds with different attachment mode of the biphenyl unit and the diphenylhydroxymethyl-substituted equivalent.

The synthesis, structural and chemosensing properties of several lower rim-dansylated calix[4]arenes bearing different methylene bridge substituents are described. Compared to bridge-unsubstituted pendants neither the conformational nor the fluorescence characteristics of the calixarene core are perceptibly influenced by the bridge substituent. X-ray structure as well as NMR measurements indicates the lower rim-propoxylated and-dansylated calixarenes to adopt the cone conformation capable of the complexation of Cu2+ ions at micromolar level. Fluorescent measurements point to selective 1:2 calixarene: Cu2+ complex formation with sensing parameters being of a suitable level to make the use as a potentially immobilisable chemosensor for the detection of Cu2+ ions promising.

Two new linker-type molecules 1a and 1b composed of o-hydroxyacetophenone coordinative groups attached to linear ethynylene or 1,4-phenylenediethynylene spacer units have been synthesised and structurally characterised. An X-ray crystallographic study for both compounds has shown structures with strong intramolecular hydrogen bonds fitting in the model of ‘Intramolecular Resonance Assisted Hydrogen Bond (IRHAB)’. Initial coordination experiments with Cu(II) were performed and the resulting materials characterised by PXRD. The similarity of the copper coordination between these compounds and copper(II) acetylacetonate complexes was demonstrated by XPS measurements. Based on the evidence of these studies, and on elemental analysis, the formation of the corresponding coordination polymers comprising Cu(II) and the linkers has been proposed

Two new crystalline host compounds of bisfluorenol type featuring an elongated core structure compared to a known parent molecule (2,2′′-[1,1′:4′,1′′]-terphenylyl versus 2,2′-biphenylyl) have been synthesized. Crystalline inclusion compounds involving protic guest molecules have been prepared and studied with reference to their crystal structures. Conformational changes as against the prototype compound due to prevention of the intramolecular hydrogen bond between the hydroxy groups give rise to a specific mode of host–guest association, showing preference to the formation of infinite hydrogen bonded chains instead of discrete host–guest units. Potentiality for crystal engineering using respective two-component molecular systems is indicated.

Fourteen new derivatives of 9,10-anthraquinone or 9,10-dimethoxyanthracene were designed, synthesised and characterised. Regarding the structure, the compounds are π-conjugated (cross and linear, respectively) and feature thiophene terminated side arms attached to five different positions of the anthraquinone or anthracene core. The synthesis of the compounds involves a cross-coupling procedure in the key reaction steps. Crystal structures of compounds 5 and 19 have been studied. The thiophene containing title compounds 1–5 can be reduced and oxidised by a two step redox process. The electrochemical parameters have been analysed by cyclic voltammetry (CV). Theoretical calculations in the framework of all-electron density functional theory (DFT) were used to investigate the electronic structure of the individual free molecules. Furthermore, calculations of the transport properties of model devices containing compounds 1–3 and respective reduced hydroquinone derivatives assembled at Au(111) electrodes were carried out to evaluate their potential for the application as redox-active switches.

The new linker-type ligand 1, featuring two L-phenylalanine-terminated urea moieties attached to the para positions of a central phenylene unit has been synthesized. Its coordination polymer formed with lead(II) and containing DMF and water as solvent molecules has been prepared and structurally studied by X-ray crystallography.

The diol host compound 2 has been synthesised and its behaviour to form crystalline inclusion compounds is discussed in comparison with an analogous ethynylene spaced host compound 1. The rotation around the fluorenol–anthracene bonds in 2 is highly restricted as indicated by solution NMR spectroscopy, molecular mechanics and semi-empirical calculations. Single-crystal X-ray structures of the inclusion complexes of 2 with 1-BuOH (2a), morpholine/H2O (2b) and DMSO (2c) are in agreement with the bent geometry of the anthracene ring system suggested by the calculations. The structures exhibit specific modes of hydrogen bond interactions.

X-ray crystal structures of several novel diametrically bridge-disubstituted calix[4]arenes are presented, revealing the calixarene core in the rare 1,2-alternate conformation. Structural comparisons suggest a tunable inclusion behavior depending on the bridge substituents, which is a promising tool for supramolecular host guest design in terms of “synthon engineering”.

In the title compound, C30H20O2S2, the dihedral angles between the central azulene ring system (r.m.s. deviation = 0.039 Å) and the pendant benzene rings are 28.96 (7) and 55.15 (7)°. The dihedral angles between the benzene rings and their attached acetylsulfanyl groups are 59.60 (10) and 84.79 (10)°. The expected π–π stacking interactions are not observed in the crystal structure; instead, the packing features C—H...O hydrogen bonds, which link the molecules intoC(12) [010] chains, which are supported by weak C—H...π contacts.

The formation of crystalline host–guest complexes of three constitutionally isomeric host compounds 1–3 featuring two diphenylhydroxymethyl groups attached in different positions to a biphenylylene central moiety is studied. Dependent on the connection mode (2,2′-, 3,3′-, or 4,4′-) with reference to the biphenylylene unit, a distinctly different complex behavior of the host compounds is observed. X-ray crystal structures of the solvent-free hosts are reported including a third polymorph with respect to already known polymorphous structures. The crystal structures of eight host–guest complexes of 1–3, including a pair of complexes differing only in the host/guest stoichiometry, are described and comparatively discussed covering the structures of known complex species of the isomeric hosts. Correlations between the constitutional isomerism of the host molecules and their conformational as well as packing structures in the crystalline state, both in unsolvated and solvent complexed form, are demonstrated pro...

The X-ray crystal structure of an acetonitrile solvate of 5,11,17,23-tetra-tert-butyl-26,28-dihydroxy-25,27-dimethoxycalix[4]arene that is 1a, showing the unusual coexistence of two basic conformations in the crystal, that is, cone and 1,2-alternate, is analyzed. In contrast to this conformational coexistence of crystallographically independent molecules, the predominant conformation in solution and also in the related toluene (1b) and toluene/acetonitrile (1c) solvates is the cone conformation. With the help of calculations on the ground state energy of the single conformers and DSC measurements as well as crystallization experiments of 1 in toluene/acetonitrile mixtures of different ratio a possible explanation of this phenomenon is given.

A new trigonal host molecule 1 featuring three 4-(9-hydroxy-9-fluorenyl)phenyl units symmetrically attached to a benzene core was synthesized and is shown to yield a 1:3 (host:guest) crystalline inclusion compound with DMSO (1a). The crystal structure of 1a is distinguished by a rare case of piedfort arrangement of host molecules and a unique hexameric cluster formation of DMSO.

Three upper rim site lipophilic calix[4]arenes 1–3 featuring different para-alkanoyl substituents at the phenolic moieties, i.e.n-hexanoyl, n-octanoyl and 3-cyclohexylpropanoyl groups, are reported to complex, aside from the common solvent molecule n-butanol, different keto and hydroxylic terpene guest molecules such as (−)-menthone, (−)-menthol or (+)-carvone in the solid state. Although for all six inclusion compounds described here, a strict 1 : 1 host : guest stoichiometry is observed, complementary size and polarity relationships between the cone shaped calixarene cavity and the guest molecule emerge from single crystal X-ray structural study. Dependent on the structure of the guest molecule, the calixarenes are arranged in a head-to-head or head-to-tail orientation in the crystalline packing, giving rise to capsular or otherwise deeply enclosed inclusion mode of the guest molecules, respectively. Furthermore, the O-acyl atoms of the calixarenes were found to be directly involved in host–guest interaction. In order to estimate the degree of isostructurality of the host frameworks and to examine the influence of the guest molecules on the solid-state conformation of these calixarene molecules, isostructurality comparison, cell similarity and molecular isometricity calculations were carried out revealing a rare case of supramolecular morphotropism for the pair of (−)-menthone and (−)-menthol inclusions of the n-hexanoyl substituted calixarene. Structure–inclusion property relationship was examined by QMB measurements of thin layers of the calixarenes. Vapor studies with different terpenes and common organic solvents show an increased affinity towards guest molecules with polar functionalities, whereas small solvent molecules like acetone are bound considerably better than the more bulky terpene molecules.

Crystal structures of the configurational isomers of benzil monoxime (1 and 2), a p-methoxy derivative (3) and its solvated species with triethylamine (3a) are reported showing specific influences of the molecular configuration, substitution and solvation on the conformational property and packing behaviour of the molecules. Based on the observed interdependences, in particular involving modes of interaction, potential utilization of the 1,2-dione monoxime functional unit for the purpose of crystal engineering seems promising.

The new host compounds 2 and 3 containing a biphenyl or terphenyl moiety attached to the 1-position of a bulky 2,3,4,5-tetraphenylcyclopentadiene-1-ol building unit have been synthesized. Crystal structures of corresponding inclusion complexes with n-hexane (2a), DMSO (2b) and THF (3a) are reported and comparatively discussed involving known inclusion structures of 1, being the parent of this particular class of host molecules. The structural modification from 1 via 2–3 gives rise to distinct changes of the inclusion property concerning molecular assembly and stoichiometric ratio of the crystal components.

The aromatic monoboranes 1, 2 and bisboranes 3, 4 of which 4 is a newly synthesised compound have been studied with reference to their supramolecular behaviour in the crystalline state. While the monoboranes crystallise purely, the bisboranes form channel-type solvent inclusions with m-xylene (3a) and nitrobenzene (4a) in the crystals, showing their potential as clathrate hosts in the realm of optically and electronically interesting compounds.

Three lower rim n-propyl substituted calix[4]arenes (1–3) with varied number and position of the modifying groups have been prepared. Inclusion compounds (five species) involving different kinds of guest solvents have been isolated. Their X-ray crystal structures were determined and comparatively discussed using isostructurality calculations. Two of the inclusion compounds obtained (1a and 1b) are polymorphs containing the same host and guest molecules in equal stoichiometric ratio but different Z′ values caused by a phase transition around 140 K. The inclusion compounds 2a and 2b refer to the interesting case of a mixed solvent complex while 3a allows studying the effect of full lower rim n-propyl substitution.

Two host compounds 2,7-dibromo-9-ethynyl-9-fluorenol (1) and 2,7-dibromo-9-trimethylsilylethynyl-9-fluorenol (2) were synthesized and their inclusion properties studied. Crystals of the host compounds show interesting change of colour from yellow to colourless upon guest complexation. To determine this phenomenon the crystal structures of guest-free compounds and five selected clathrates, involving diethylamine, triethylamine, pyridine, and 1,4-dioxane as the guest, have been determined by X-ray diffraction. The various modes of supramolecular interaction observed in these crystals are used as a basis for explaining colour changes accompanying guest inclusion.

International audience; Four crystalline inclusion compounds of the 2,2'-bis(9-hydroxy-9-fluorenyl)biphenyl host 1, containing diethylene glycol (1:1) (1a), bis(2-aminoethyl)amine (1:1) (1b), methacrylic acid (1:1) (1c) and 2-cyclopenten-1-one (1:2) (1d), have been studied by X-ray diffraction analysis from single crystals. Departure from the expectation, the multifunctional and conjugate functional guest molecules, potentially being able to offer multiple H donor-/acceptorships or other modes of polar interaction due to the conjugation, do not result in the formation of infinitely connected networks in the crystal structures. Instead of this, discrete 2:2 host-guest aggregates (1a, 1b), guest dimers (1c) and rather conventional host-guest units (1d) are found. Hence, inherent shielding effects of the host molecule owing to the fluorenyl moieties and the presence of a strong intramolecular hydrogen bond, impeding multiple intermolecular association, are not overcome by the merits of the guest molecules, showing that the host compound 1 is superior by structural constancy in its crystalline inclusions.

The new cyclophane type host compounds 1–3, containing rigid aromatic units and two exo-topic carboxylic acid functions, have been synthesized. Crystalline solvent inclusions, involving the dicarboxylic acid hosts and their corresponding ester intermediates 6 (a–c), namely 1·DMSO (1:4), 2·pyridine (1:3), 3·pyridine (1:4), 6a·pyridine (1:2) and 6a·benzene (1:2), have been prepared and studied using X-ray diffraction on single-crystals. Moreover, X-ray structure analyses of the solvent-free crystals of the 6 (a, b) intermediates were also carried out for comparison. Co-crystals of the carboxylic hosts 1–3 contained H-bonded 1:2 host-guest associates as building blocks, together with additional space-filling guests, whereas only loosely bounded space-filling solvent molecules were found in the two solid inclusion compounds of the 6a cyclophane ester host. In addition to the mentioned conventional H-bond interactions between carboxylic hosts and their guests, the crystal structures proved to be held together ...

The simple triarylmethanol hosts, 2 and 4, and their silicon analogues, I and 3, have been studied for comparison of the formation of crystalline inclusion compounds. Clathrate formation experiments showed that replacement of the carbinol C atoms in 2 and 4 by Si atoms to give I and 3 resulted in a distinct increase of the capability to form inclusion compounds with organic guests, in particular with alcohols. Moreover, the naphthyl derivatives are much more efficient than the phenyl species, irrespective of the carbinol and silanol features. In order to investigate and compare the guest recognition modes and packing relations of hosts 1-4 in their crystalline inclusion compounds, I I selected co-crystals, namely 1-DMSO (2:1), 3-EtOH (1: 1), 3-i-PrOH (1: 1), 3-acetone (1: 1), 3-DMSO (1: 1), 3-THF (1: 1), 3-piperidine (1: 1), 4-acetone (1: 1), 4-DMSO (1: 1), 4-1,4-dioxane (1: 1) and 4-benzene (1: 1), were studied by X-ray diffraction from single crystals. The survey contains additional I I crystal structures from the literature and provides a detailed discussion of isostructurality relationships. Journal of Inclusion Phenomena and Macrocyclic Chemistry

A series of compounds 1–5 featuring a structure composed of linear or trigonal ethynyl and aryl containing rigid construction elements with attached terminal adamantyl stoppers were synthesized to study their structures and enclathrating properties. While only the linear tetraethynylenic prototype molecule 1 exhibited versatile inclusion behavior, the compounds 2–5 were found to be inefficient. X-Ray crystal structures of the inclusion compounds between 1 and THF, cyclohexanol and aniline as well as of the unsolvated compounds 3, 4 and 5 are reported, throwing light on the respective modes of crystalline packing affected by molecular dimension and shape parameters.

Inclusion properties of a new family of clathrate hosts (1–4) containing two 9-hydroxy-9-fluorenyl units or chloro-, bromo- and t-butyl-substituted derivatives of this group attached in the 3,3′-position to a basic 2,2′-binaphthyl construction element are reported (115 examples of clathrates). The crystal structures of six selected clathrates, involving dimethylsulfoxide, cyclopentanol, diethylether, benzylamine, chloroform and acetone as the guest, have been determined by X-ray diffraction, showing varied modes of supramolecular interaction dependent on the host and guest constitutions, while the formation of an intramolecular hydrogen bond between the hydroxy groups of the fluorenol units is a common structural feature (except in 3a) controlling twisted conformation of the host molecules.

A new onium salt host molecule 1 featuring a spiro-type ammonium backbone was synthesized and shown to form a crystalline inclusion compound with chloroform, 1 · chloroform (1:2), the crystal structure of which is reported. The host molecular interactions including C–H···Br, Cl···Cl and aromatic stacking contacts are typical of the packing structure.

A new tetrasubstituted tetraaza macrotricycle 1 was prepared and shown to form a crystalline inclusion compound with chloroform, 1 chloroform (1:2). Crystal structures of the two compounds are reported. In the unsolvated 1, tightly interlocked packing of the molecules involving π-stacking interactions of the aromatic groups is determined while in the inclusion compound with chloroform the solvent molecules are accommodated into channels possessing C—H···FFN contact to 1.

New host molecules, 1(a, b) and 2(a, b), each containing two bulky borneol or fenchol terminal groups attached to ethynylene central units of different lengths, have been synthesized. Their properties of crystalline inclusion with a variety of organic guests, including alcohols, amines and dipolar aprotic compounds, are reported (26 examples of inclusion compounds). The crystal structures of four selected inclusion compounds have been determined by X-ray diffraction, showing varied modes of supramolecular interaction dependent on the host and guest constitutions. Varying stoichiometries, host–guest compositions and appearance of disorder all indicate match/mismatch phenomena in the molecular recognition process under the build-up of macroscopic crystals. All these crystalline associations are organized through the hydrogen bonding capability of the host hydroxyl groups, thus corresponding to coordinato-clathrate scenery.

Two clathrates between the 2,2‘-bis(9-hydroxy-9-fluorenyl)biphenyl host and chloroform guest, having 1:2 (α-phase) and 1:1 (β-phase) stoichiometries, have been obtained in the same vial by fast evaporation of a supersaturated solution in chloroform. The structures of the pseudodimorphs were determined by single-crystal X-ray diffraction. Their thermal properties were studied by using combined thermogravimetry-differential scanning calorimetry (TG-DSC), variable temperature X-ray powder diffraction in the temperature interval 20−250 °C, and DSC in the low-temperature interval from −140 to 20 °C. The thermal decomposition behavior of the α- and β-phase pseudodimorphs, a difference in the desolvation onset temperatures, as well as an occurrence of endothermic peaks in the low-temperature DSC curves (order−disorder transition of the guest component) have been explained on the basis of the structural data.

The reactions of substituted dichlorosilane monomers,Cl2SiRR′, with two equivalents of lithium aryl acetylide(1), LiC ≡ C-4-C6H4-Ph, afford RR′Si(C ≡ C-4-C6H4-Ph)2 (6: R,R′ =CH3; 7: R = CH3, R′ = CH=CH2; 8: R,R′ = Ph). An isomeric mixture of meso, (R,R)- and (S,S)-Bis[2-(N,N-dimethylaminomethyl)ferrocenyl]dichlorosilane (5) was used as starting chlorosilyl compound for reaction with LiC ≡ C-4-C6H4-Ph to give (FcN)2Si(C ≡ C-4-C6H4-Ph)2 (9). A detailedcharacterization of 6, 7, 8 and 9 has been carried out by 1H-NMR, 13C-NMR, 29Si-NMR, IR and UV-VIS spectroscopy. The crystal structure of 9 has been determined by X-ray diffraction analysis.

New organosilicon compounds 1–3 featuring bulky triphenylsilyl moieties attached to rigid linear or trigonal spacer units have been synthesized and demonstrated to act as clathrate hosts, yielding crystalline inclusion compounds mostly with apolar and aprotic dipolar guest molecules, while the nonbulky dimethylphenylsilyl or trimethylsilyl substituted analogous compounds 4 and 5, which were also synthesized, proved inefficient. X-ray crystal structures of the inclusion compounds 1·DMF (1:1), 1·pyridine (1:1), 2·1,4-dioxane (2:1), 2·pyridine (2:1), 2·p-xylene (2:1), 2·H2O (2:1) as well as of the unsolvated compounds 2 and 5 are described, and thermal stability studies of selected clathrates are reported.

An improved crystal structure of the title compound, C6H6N2O3, is reported. The structure, previously solved [Liet al.(1987).Jiegou Huaxue (Chin. J. Struct. Chem.),6, 20–24] in the orthorhombic space groupPca21and refined toR= 0.067, has been solved in the orthorhombic space groupPbcmwith data of enhanced quality, giving an improved structure (R= 0.0485). The molecule adopts a planar conformation with all atoms lying on a mirror plane. The crystal structure is composed of molecular sheets extending parallel to theabplane and connectedviaC—H...O contacts involving ring H atoms and O atoms of theN-oxide and nitro groups, while van der Waals forces consolidate the stacking of the layers.

The asymmetric unit of the title compound, C8H3BrN2, consists of two molecules. The crystal structure features undulating molecular sheets with the molecules linked by C—H...N hydrogen bonds with one N atom acting as a bifurcated acceptor. N...Br interactions also occur [N...Br = 2.991 (3) and 3.099 (3) Å]. Interlayer association is accomplished by offset face-to-face arene interactions [centroid–centroid distance = 3.768 (4) Å].

A new type of dumb-bell-shaped host molecule (6-8) has been synthesised, of which 1,8-bis((1)-adamantyl)-1,3,5,7-octatetrayne (8 = BAOT) forms an open porous architecture when cocrystallised with a number of typical solvent molecules. Adamantyl substituents attached to a tetraalkyne spacer build up the walls of parallel channels wherein guest molecules are aligned. Surprisingly, the tetraalkyne unit is significantly bent. Desolvation experiments provide evidence for a reversible inclusion of guests. In the case of the inclusion of 2-butanone, a partial substitution by symmetrical and asymmetrical long-chain chromophores during crystallisation was possible. Stained crystals showed optical frequency doubling. The crystal structure analysis revealed a centric space group, although considerable translational and orientational disorder was present. Application of scanning pyroelectric microscopy revealed that the growth of inclusion compounds with 2-butanone produced polar ordering of guest molecules, which were aligned in two macro-domains of opposing polarity. The resulting orientation of the carbonyl dipoles is in agreement with the theoretical prediction of a Markov model of spontaneous polarity formation based on molecular recognition processes on growing crystal faces. The present case represents a new example of a property-driven supramolecular synthesis.

The title compound, C22H19NO4S, has an almost planar geometry supported by intramolecular N—H...O and C—H...O hydrogen bonds. The thiophene ring is inclined to the azulene ring by 4.85 (16)°, while the ethoxycarbonyl groups are inclined to the azulene ring by 7.0 (2) and 5.7 (2)°. In the crystal, molecules are linked by pairs of N—H...O hydrogen bonds, forming inversion dimers with anR22(12) ring motif. The dimers are linkedviaC—H...π interactions, forming sheets parallel to (10-1).