Themed collection 1st International Conference on Noncovalent Interactions

Welcome to this themed collection of RSC articles entitled: 1st International Conference on Noncovalent Interactions.

The application of weaker intermolecular attractions to the formation of crystals with desired physical and chemical properties is described. Representative structural examples are analysed critically and approaches are outlined for the future development of this important area.

Quantification of noncovalent interactions is the key for the understanding of binding mechanisms, of biological systems, for the design of drugs, their delivery and for the design of receptors for separations, sensors, actuators, or smart materials.

For various interactions electron charge shifts try to protect the former doublet or octet electronic structure of the Lewis acid centre.

This Perspective highlights the use of chalcogen bonding as a versatile synthon for the synthesis, catalysis and construction of both organic and inorganic materials.

This perspective examines the progress that has been made in using non-covalent interactions to control regioselectivity and site-selectivity in catalysis.

Hydrogen bonds with organic fluorine and other halogens as acceptors show a consistent picture in gas and solution phase in agreement with computations, whereas conflicting conclusions were drawn from crystallographic analyses.

Biomolecular building blocks (H-bonded and stacked base pairs) determine the structure of biomolecules (DNA).

Some strategies for driving co-crystal synthesis using a variety of competing non-covalent interactions are presented.

Far infrared spectroscopy as a tool for the study of inter and intramolecular interactions in complex molecular structures.

The development of solution-based anion receptor molecules which exploit halogen bonding interactions is an emerging area of research. This Feature Article reviews recent advances which have been made in this rapidly developing field, surveying the use of iodoperfluoroarene, haloimidazolium and halotriazole/triazolium halogen-bond-donor motifs in anion receptor design and describing the application of mechanically interlocked rotaxane and catenane frameworks as halogen bonding anion host systems.

This article highlights how π-stacking interactions have an important influence on the catalytic properties of transition metal complexes decorated with rigid polyaromatic ligands.

The formation of hydrogen bonding networks of nalidixic acid–Cu(II) complexes is discussed and may be a possible pathway leading to improved properties and increased efficiency of this antibiotic.

A perfluorinated aromatic link was used as a synthon in the design of bis-azo dyes.

Herein, we report the synthesis and crystal structures of three [2+2] supramolecular boxes assembled by halogen bonding.

DFT calculations reveal that a coordinating THF plays an essential role in regulating the stereoselectivity via C–H⋯π noncovalent interaction.

In the crystals of racemic axially chiral quinazolinones, the formation of intermolecular halogen bonds was detected.

Novel halogen bonded cocrystals of aromatic aldehydes have been synthesized. We present the halogen bond acceptor potential of the aldehyde group oxygen atom in competition with the hydroxy, methoxy and pyridine groups.

All-photonic and reversible switching of the composition of a supramolecular network is enabled by employing a dithienylethene guest.

The α-iodosulfone moiety acts as a new and effective halogen bond donor system in the solid state and in solution.

A bicomponent blend of linear building blocks leads to intermolecular halogen bonding, resulting in the formation of hexagonal arrays.

Herein, a series of halogenated UiO-66 derivatives was synthesized and analyzed for the breakdown of the CWA simulant dimethyl-4-nitrophenyl phosphate (DMNP) to analyze ligand effects.

The direct and selective α-halogenation of alkyl sulfones was achieved via base-mediated electrophilic halogenation, where reagent–solvent halogen bonding was found to control the selectivity through alteration of the effective size of the halogen source.

Key findings regarding the effects of ligand preorganisation via halogen bonding on the outcome of reactions at rhodium are reported.

The graphic shows a halogen bonding interaction between a tetrapodal platform attached to a 2-iodo-imidazole unit and bromide in water.

A host–guest FRET pair based on a carboxyfluorescein-labelled cucurbit[7]uril and DAPI was developed to sense DNA ratiometrically.

Weak though structure determining interactions exist between benzene and F₃CI or F₃CCH₂I; their natures are quite different and lead to different types of networks.

Something learnt from a golden trio: polymorphs of a [Au(NHC)₂][Au(CN)₂] double salt allow an understanding of the thermochromic and mechanochromic phosphorescence of the gold(I) complexes with extended aurophilicity.

An exceptionally strong synergy between aromatic π-stacking and n → π* interaction.

The cocrystal of triphenylphosphine with 1,3,5-trifluoro-2,4,6-triiodobenzene features a rare, moderately strong, and linear phosphorus–iodine halogen bond.

Herein we report the X-ray characterization of four sildenafil solvates where the conformation of the pyrazolo[3,4-d]pyrimidine and phenyl rings depends on the solvent.

The Br⋯N bonds in a series of halogen-bonded complexes change gradually from the typical intermolecular to the traditional covalent bond.

An in-depth structure database investigation and experimental charge density analysis of the OC⋯OC π-hole tetrel bonds.

Pallas's shine: extended intercationic Pd⋯Pd contacts of 3.30 Å show distinct MMLCT transitions and low-energy emissions.

A set of molecules locked in the CH⋯O H-bonding conformation has been used to correlate the magnitude of the downfield shift of the ¹H NMR signal due to the bridging hydrogen with the hybridization state of the acceptor oxygen and the CH⋯O H-bond strength.

Halide ions and tetraiodoethynyl-featured tetraphenylmethane are successfully assembled into robust diamond-like networks in the presence of tetraphenylphosphonium cations.

A supramolecular motif listed as ‘carbon bonded’ or ‘hydrogen bonded’ may have the character of both. We highlight the hybrid character of the non-covalent interaction in a bis-Schiff base of N-allyl isatin by combining theory and experiment.

Dispersion forces govern the interaction of graphene with mono- and tripodal pyrene–[60]fullerene derivatives and direct the formation of graphene nanobuds.

The self-assembly of strategically designed triazine-containing alkynylplatinum(II) terpyridine complexes yielded sophisticated helical ribbons through a balance of multiple non-covalent interactions.

The organization of a molecular Fe^III complex embedded in a halogen-bonded 2D network is chemically tuned to trigger temperature- and light-induced spin-state switching.

In situ ³¹P solid-state NMR studies of mechanochemical halogen bond formation provide insights into the cocrystallisation process and an estimate of the activation energy.

N-Oxides can act as tridentate halogen bond acceptors, or as tetradentate ligands in a pseudo-μ₄ mode with silver(I).

Flurorine promotes the electrophilicity of sulfur to the point that chalcogen bond formation affects the crystal packing in the solid.

Within the CSD sp² O-atoms cluster closer to the π-hole of NO₃⁻ when nitrate is coordinated to a metal.

Third-generation crystal engineering: using halogen bond/hydrogen bond equivalence.

The cationic complex [Fe(qsal)₂]⁺ (Hqsal = N-(8-quinolyl)salicylaldimine) is encapsulated in halogen-bonded 1D and 2D supramolecular networks to modulate its spin-state.

The common electrostatic features of ethynyl and iodoethynyl hydrogen- and halogen-bond donors, respectively, lead to synthon mimicry which can be employed in synthetic crystal engineering for the construction of identical supramolecular assemblies in the solid-state.

Metal-involving halogen bonding was detected in a series of associates of CHI₃ with trans-[PtX₂(NCNAlk₂)₂] (X = Cl, Br).

Demonstrating the power of network topology analysis on a 46 000 ų unit cell containing 12 independent Ag(I) coordination entities.

When two different H-bond acceptors compete for a single H-bond donor, the outcomes in crystal structures of simple molecules are consistent with the results of solution phase measurements in non-polar solvents.

The competition of two σ-hole(Bi)⋯π interactions is responsible for disorder of the benzene moiety in the crystal of bismuth(III) heteroboroxine–benzene complex.

Four Au–(μ-phosphinite)–In units form an unprecedented Au₂In₂ 12-membered metallacycle which intersects at the In centres an 8-membered ring containing two In–μ-phosphinate linkages, resulting in a tricyclic structure.

Infinite water clusters with a T5(2) motif were observed in porous crystals of 4-nitrostyrylpyridine hydrochloride, the behavior of which was revealed by solid-state ¹⁷O NMR spectroscopic analyses.

A CSD analysis and DFT study reveal that the nitrogen lone-pair in [N(PPh₃)₂]⁺ is partially intact and involved in intramolecular hydrogen bonding.

The positive ESPs that underlie anion-binding by N-heterocycles do not stem from a depletion of π-electron density, as widely assumed.

A series of photoresponsive halogen-bonded liquid crystals (LCs) were successfully constructed using molecular halogen and azopyridine compounds, which show interesting properties of photoinduced phase transition upon UV irradiation.

We report crystallographic evidence for the significance of C–H⋯π hydrogen bonds in the crystal stabilization of 1,4-di-O-benzoyl-myo-inositol. The strength of this otherwise weak hydrogen bond matches with the strength of O–H⋯O hydrogen bonds.

Intermolecular interactions of the cyclic conjugated molecule (DBA) with hydrogen, nitrogen and carbon dioxide molecules were evaluated by high level ab initio calculations.

Bundling of the hydrogen bonded 2-fold helical columns has been altered on the basis of a robust halogen bond between an iodine and anionic oxygen atom. This alteration causes a change of the space groups of the resulting crystals.

The possibility of regioselective activation of a dinitrile towards nucleophilic attack using a resonance-assisted hydrogen bond system is demonstrated.

A new type of concerted halogen bond–hydrogen bond interaction was found in the solid state structure of [RuI₂(H₂dcbpy)(CO)₂]⋯I₂⋯(MeOH)⋯I₂⋯[RuI₂(H₂dcbpy)(CO)₂].

We test whether the similarities between halogen and hydrogen bonds could be used to design a surface-confined halogen-bond based network.

Site-selective nitrenoid insertions are made possible with a postfunctionalized dirhodium(II)-catalyst equipped with a remote hydrogen bonding site.

A Double Mutant Cycle is built up using a supramolecular cage that binds two aromatic carboxylates in a stacked geometry is used to quantify aromatic stacking interactions.

Nanobowls with controlled openings and interior holes are created by self-assembly of homopolymers with hydrogen bonding and π–π interaction.

Multivariate correlation analysis, including designer π-interaction derived parameters, was applied to the study of the enantioselective fluorination of homoallylic alcohols via chiral anion phase transfer (CAPT) catalysis.

Studies of X–Ni–C₆F₄I⋯X–Ni–C₆F₄I halogen-bonded networks reveal pronounced differences between fluoride (X = F) and other halides: the ¹⁹F-MAS NMR spectrum is a sensitive probe of the halogen bond.

Alcohol solvents are significantly more polar than expected based on the measured H-bonding properties of monomeric alcohols in dilute solution.

Choice of solvent is used to direct the formation of either hydrogen bonds or halogen bonds in competitive self-assembly.

Borromean rings in black and white marble decorate Cappella Ruccellai (left, Florence) and were self-assembled under halogen bond control (right).