Weak Intermolecular Interactions in the Solid State

Contemporary research in Supramolecular Chemistry is focused on the studies of weak noncovalent intermolecular, viz. supramolecular interactions as the driving force in self-assembly and molecular recognition, especially important being the solid state studies by single crystal X-ray diffraction. Recent advances have been achieved in the studies on hydrogen and halogen bonded systems, π···π, cation ···π, CH···anion, anion···π interactions and metal ion coordination in molecular self-assembly and molecular recognition in various systems such a resorcinarenes, ditopic receptors, rotaxanes and 6 4 L M tetrahedra

Exploring the role of neutral/ionized TPI hydrogen bonds and OPI halogen bonds for multifacial recognition in 5-halouracils/aminoazine cocrystals

Ten new heterodimers were synthesized in different stoichiometry to explore the role exerted by potential proton-transfer reactions in the supramolecular structures of A-B cocrystals formed by 5-haloderivatives of uracil (halogen = F, Cl, Br, I; coformer A) coupled with aminoazines as 2-aminoadenine simulants (melamine, 2,4,6-triaminopyrimidine, 2,6-diaminopyridine; coformer B) for pyrimidine nucleobase recognition. The crystallographic analysis showed that in all binary cocrystals the expected three-point hydrogen bonds (TPI), charged or uncharged depending on the acid/base properties of the components, were used for WC interfacial recognition. Moreover, the general ability of pyrimidine nucleobases to provide electron donating groups to halogen bonding has been confirmed in six of eight cocrystals containing the 5-bromo or 5-Iododerivatives coupled with 2,4,6-triaminopyrimidine or 2,6-diaminopyridine. “Lateral” one-point halogen bonds cooperate with hydrogen bonds in directing the overall crystal structures. Considerations of the relative acidities of coformers A and of the relative basicities of coformers B allowed us to design and characterize by single-crystal X-ray diffraction the first ternary pyrimidine nucleobase-containing cocrystal based on the JANUS-WEDGE concept [1]: the (1:1:1) triad showing a 2,4,6-triaminopyrimidine molecule wedged via neutral and ionized TPI between the 5-fluorouracil/1-methyluracil pair in reverse WC fashion (Fig. 1)

Trans-Bis[bis(diphenylphosphino)methane-κ2P,P′]dichlororuthenium(II) dichloromethane disolvate acetone hemisolvate hemihydrate

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(E)-7-(Pyren-1-yl)hept-6-enoic acid

The title compound, C23H20O2, is a precursor of a pyrene-based supra­molecular element for non-covalent attachment to a carbon nanotube. The asymmetric unit contains three independent mol­ecules. The carb­oxy­lic acid group in each of these mol­ecules serves as an inter­molecular hydrogen-bond donor and acceptor, generating the commonly observed double O—H⋯O hydrogen-bond motif in an eight-membered ring. Weaker C—H⋯O, π–π [centroid–centroid distance = 3.968 (4) Å] and C—H⋯π inter­actions are also found in the crystal structure

cis-Aquabis[bis(diphenylphosphino)ethane-j2P,P000]chlororuthenium(II) hexafluorophosphate dichloromethane sesquisolvate hemihydrate

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cis-[Bis(diphenylphosphino)ethane-κ2P,P′]dichlororuthenium(II) dichloromethane disolvate

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Three 2,5-dialkoxy-1,4-diethynylbenzene derivatives

2,5-Diethoxy-1,4-bis[(trimethylsilyl)ethynyl]benzene, C(20)H(30)O(2)Si(2), (I), constitutes one of the first structurally characterized examples of a family of compounds, viz. the 2,5-dialkoxy-1,4-bis[(trimethylsilyl)ethynyl]benzene derivatives, used in the preparation of oligo(phenyleneethynylene)s via Pd/Cu-catalysed cross-coupling. 2,5-Diethoxy-1,4-diethynylbenzene, C(14)H(14)O(2), (II), results from protodesilylation of (I). 1,4-Diethynyl-2,5-bis(heptyloxy)benzene, C(24)H(34)O(2), (III), is a long alkyloxy chain analogue of (II). The molecules of compounds (I)-(III) are located on sites with crystallographic inversion symmetry. The large substituents either in the alkynyl group or in the benzene ring have a marked effect on the packing and intermolecular interactions of adjacent molecules. All the compounds exhibit weak intermolecular interactions that are only slightly shorter than the sum of the van der Waals radii of the interacting atoms. Compound (I) displays C-H...pi interactions between the methylene H atoms and the acetylenic C atom. Compound (II) shows pi-pi interactions between the acetylenic C atoms, complemented by C-H...pi interactions between the methyl H atoms and the acetylenic C atoms. Unlike (I) or (II), compound (III) has weak nonclassical hydrogen-bond-type interactions between the acetylenic H atoms and the ether O atoms.info:eu-repo/semantics/publishedVersio