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Anion–π interactions, intuitively repulsive forces, turned from controversial to a well-established non-covalent interaction over the past quarter of a century. Within this time frame the question “Anion–π interactions. Do they exist?” could be answered and even more importantly its functional relevance was proven. The present feature article summarizes the experimental findings of anion–π studies in the gas phase, solution and in the solid state and highlights the application of anion–π interactions in anion recognition, sensing and transport as well as in catalysis. Moreover, the biochemical relevance of this weak intermolecular force is comprehensively reviewed. [ABSTRACT FROM AUTHOR]

Crystal engineering provides tools to the rational design of materials with desired structures or properties. We have exploited the analogy between hydrogen bonds and halogen bonds to trap I2 in the channels of crystal structures, thus stabilizing the otherwise unfavourable tetrahalides via charge transfer interactions. [ABSTRACT FROM AUTHOR]

The syntheses and full characterization of novel ruthenium complexes based on 1,3-dicyanobenzene are described. Crystal structures are reported for both [1,3-(cis-RuCl(P(CH3)3)4N≡C)2C6H4][PF6]2 (1cis) and [1,3-(trans-RuCl(dppe)2N≡C)2C6H4][H2PO4]2 (3′). Ligand substitution in the homobimetallic complex (3) leads easily to the monometallic analogue, [1,3-(trans-RuCl(dppe)2N≡C)C6H4(C≡N)][PF6] (4). A heterobimetallic complex, [1,3-(trans-RuCl(dppe)2N≡C)C6H4(C≡N–FeCp(dppe))][PF6]2 (5), of satisfactory purity is also obtained. [Copyright &y& Elsevier]

Review: [88 refs. [ABSTRACT FROM AUTHOR]

Enantiomerically pure cyclohexylhemicucurbit[8]uril (cycHC[8]), possessing a barrel-shaped cavity, has been prepared in high yield on a gram scale from either (R,R,N,N′)-cyclohex-1,2-diylurea and formaldehyde or cycHC[6]. In either case, a dynamic covalent library is first generated from which the desired cycHC can be amplified using a suitable anion template. [ABSTRACT FROM AUTHOR]

The binding of different categories of alkyl ammonium (secondary and tertiary mono- and di-ammonium) salts with resorcinarenes and a pyrogallarene through weak interactions was analysed in all phases. 1H NMR spectroscopy and electrospray ionisation mass spectrometry were utilized in analysing the complexes in solution and in the gas phase, respectively. The 1H NMR titration studies in methanol-d4 reveal that the association constants for the 1 : 1 complexes vary according to the electronic properties of the hosts as well as the size, geometric orientation and charge concentration of the guest cations with binding constants of up to 950 M−1 in some cases. Mass spectrometry reveals 1 : 1 monomeric and 1 : 2 dimeric complexes in the gas phase. Six co-crystals, three of which are dimeric host–guest capsular assemblies, two open inclusion complexes and a pseudocapsular methanol solvate, were analysed in the solid state through single-crystal X-ray diffraction. The crystal structures confirm that the complexes are held together by multiple cation…π, CH…π and hydrogen bond interactions. [ABSTRACT FROM AUTHOR]