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The title compound, C18H21N3O3, was prepared from 1,3,5-benzenetricarbonyl trichloride and cyclopropylamine. Its crystal structure was solved in the monoclinic space group P21/c. In the crystal, the three amide groups of the molecule are inclined at angles of 26.5 (1), 36.9 (1) and 37.8 (1)° with respect to the plane of the benzene ring. The molecules are linked by N—H...O hydrogen bonds, forming two-dimensional supramolecular aggregates that extend parallel to the crystallographic ab plane and are further connected by C—H...O contacts. As a result of the supramolecular interactions, a propeller-like conformation of the title molecule can be observed.

In the crystal structure of the title compound, C26H36N2O4, the tripodal molecule exists in a conformation in which the substituents attached to the central arene ring are arranged in an alternating order above and below the ring plane. The heterocyclic unit is inclined at an angle of 79.6 (1)° with respect to the plane of the benzene ring. In the crystal, the molecules are connected via N—H...O bonds, forming infinite supramolecular strands. Interstrand association involves weak C—H...O and C—H...π interactions, with the pyridine ring acting as an acceptor in the latter case.

In the crystal of the title compound, C18H14O10·2H2O, the arene rings of the biphenyl moiety are tilted at an angle of 24.3 (1)°, while the planes passing through the carboxyl groups are rotated at angles of 8.6 (1) and 7.7 (1)° out of the plane of the benzene ring to which they are attached. The crystal structure is essentially stabilized by O—H...O bonds. Here, the carboxyl groups of neighbouring host molecules are connected by cyclic R22(8) synthons, leading to the formation of a three-dimensional network. The water molecules in turn form helical supramolecular strands running in the direction of the crystallographic c-axis (chain-like water clusters). The second H atom of each water molecule provides a link to a methoxy O atom of the host molecule. A Hirshfeld surface analysis was performed to quantify the contributions of the different intermolecular interactions, indicating that the most important contributions to the crystal packing are from H...O/O...H (37.0%), H...H (26.3%), H...C/C...H (18.5%) and C...O/O...C (9.5%) interactions.

In the crystal structures of the formamide monosolvate (1a) and the n-propanol/H2O solvate/hydrate (1b) of the title compound, C38H50N4O3 (1), the tripodal host molecule adopts a conformation in which the substituents attached to the central benzene ring are arranged in an alternating order above and below the ring plane. As a result of the different nature of the involved guest species, the crystal components in 1a create a three-dimensional supramolecular architecture, while the crystal structure of 1b consists of two-dimensional supramolecular aggregates extending parallel to the crystallographic ab plane.

Various functional groups have been considered as acceptors for halogen bonds, but the oxime functionality has received very little attention in this context. In this study, we focus on the analysis of the hydrogen and halogen bond preferences observed in the crystal structures of 5-halogeno-1H-isatin-3-oximes. These molecules can be involved in various non-covalent interactions, and the competition between these interactions has a decisive influence on their self-organization. In particular, we were interested to see whether the crystal structures of 5-halogeno-1H-isatin-3-oximes, especially bromine- and iodine-substituted ones, are characterized by the presence of halogen bonds formed with the oxime functionality. The oxime group proved its ability to compete with the other strong donor and acceptor sites by participating in the formation of cyclic hydrogen-bonded heterosynthons oxime∙∙∙amide and Ooxime∙∙∙Br/I halogen bonds.

The complex of 2,4,6-triethyl-1,3,5-tris[(4-methyl-1H-indazol-1-yl)methyl]benzene with ammonium hexafluorophosphate, C39H42N6·NH4+·PF6−, crystallizes in the monoclinic space group P21 with two molecules of the receptor, two NH4+ and two PF6− ions in the asymmetric unit. In each of the complexes the ammonium ion resides in the cavity of the receptor molecule and is fixed in its position by three N—H...N bonds, while the remaining hydrogen atom of the cation acts as a bifurcated binding site for N—H...F bonding to the counter-anion. The crystal is composed of one-dimensional supramolecular aggregates extending along the a-axis direction.

In the crystal structure of the title compound, C30H50N4O4, the two bis(hydroxyethyl)amino moieties and the 2,4-dimethylpyridinylamino unit of the molecule are located on one side of the central benzene ring, while the ethyl substituents are oriented in the opposite direction. The dihedral angle between the planes of the aromatic rings is 73.6 (1)°. The conformation of the molecule is stabilized by intramolecular O—H...O (1.86–2.12 Å) and C—H...N (2.40, 2.54 Å) hydrogen bonds. Dimers of inversion-related molecules represent the basic supramolecular entities of the crystal structure. They are further connected via O—H...O hydrogen bonding into undulating layers extending parallel to the crystallographic bc plane. Interlayer interaction is accomplished by weak C—H...π contacts.

Abstract Among the 1,3,5-trisubstituted 2,4,6-triethylbenzenes bearing pyrazolyl groups, the compounds with 3,5-dimethylpyrazolyl moieties were found to be effective receptors for ammonium ions (NH4 +). The current study investigated the extent to which the incorporation of an additional alkyl group in the 4-position of the pyrazole ring affects the binding properties of the new compounds. 1H NMR spectroscopic titrations and investigations using isothermal titration calorimetry revealed that this small structural variation leads to a significant increase in the binding strength towards NH4 + and also improves the binding preference for NH4 + over K+. In addition to the studies in solution, crystalline complexes of the new triethyl- and trimethylbenzene derivatives, bearing 3,4,5-trialkylpyrazolyl groups, with NH4 +PF6 − were obtained and analyzed in detail. It is noteworthy that two of the crystal structures discussed in this work are characterized by the presence of two types of ammonium complexes. Studies focusing on the development of new artificial ammonium receptors are motivated, among other things, by the need for more selective ammonium sensors than those based on the natural ionophore nonactin.

The crystal structures of the title compounds, methyl 3,5-dimethylbenzoate (C10H12O2; 1), 3,5-bis(bromomethyl)phenyl acetate (C10H10Br2O2; 2) and 5-hydroxybenzene-1,3-dicarbaldehyde (C8H6O3; 3) were determined by single-crystal X-ray analysis. The crystals of 1 are composed of strands of C—H...O=C bonded molecules, which are further arranged into layers. As a result of the presence of two bromomethyl substituents in compound 2, molecular dimers formed by crystallographically non-equivalent molecules are connected to structurally different two-dimensional aggregates in which the bromine atoms participate in Br...Br bonds of type I and type II. In the case of compound 3, which possesses three donor/acceptor substituents, the molecular association in the crystal creates a close three-dimensional network comprising Caryl—H...Ohydroxy, Cformyl—H...Oformyl and O—H...Oformyl bonds.

A series of mono- and dicationic 1,3,5-trisubstituted 2,4,6-triethylbenzenes containing pyridinium groups in combination with aminopyrimidine-/aminopyridine-based recognition units were synthesized and crystallographically studied. The combination of neutral and ionic building blocks represents a promising strategy for the development of effective and selective artificial receptors for anionic substrates. In the crystalline state, the investigated compounds show a tendency to bind the counterion PF6− in the cavity formed by the three functionalized side-arms. The intermolecular interactions with the PF6− ion comprise N-H∙∙∙F and C-H∙∙∙F bonds. Detailed analysis of various supramolecular motifs, including interactions with solvent molecules, provides deeper insights into the processes of molecular recognition. The information obtained is useful in the development of new receptor molecules for anions and in the selection of the most appropriate counterion.

Abstract New representatives of 2,4,7‐trisubstituted 9,9‐dialkyl‐9H‐fluorenes were prepared and used for crystallographic investigations as well as initial binding studies towards metal ions and carbohydrates. The binding studies, which included 1H NMR spectroscopic titrations and fluorescence measurements, demonstrated the ability of the tested fluorene‐based compounds to act as complexing agents for ionic and neutral substrates. Depending on the nature of the subunits of the fluorene derivatives, “turn on” or “turn off” fluorescent chemosensors can be developed. Compounds composed of 4,6‐dimethylpyridin‐2‐yl‐aminomethyl moieties have the potential to be used as sensitive “turn‐on” chemosensors for some metal ions.