An emerging strategy for making ordered materials is modular construction, which connects preformed molecular subunits to neighbours through interactions of properly selected reactive sites. This strategy has yielded remarkable materials, including metal-organic frameworks joined by coordinative bonds, supramolecular networks linked by strong non-covalent interactions, and covalent organic frameworks in which atoms of carbon and other light elements are bonded covalently. However, the strategy has not yet produced covalently bonded organic materials in the form of large single crystals. Here we show that such materials can result from reversible self-addition polymerizations of suitably designed monomers. In particular, monomers with four tetrahedrally oriented nitroso groups polymerize to form diamondoid azodioxy networks that can be fully characterized by single-crystal X-ray diffraction. This work forges a strong new link between polymer science and supramolecular chemistry by showing how predictably ordered covalent or non-covalent structures can both be built using a single modular strategy.

An inherently chiral C -symmetric triaminotribenzotriquinacene was condensed in racemic and enantiomerically pure form with a bis(salicylaldehyde) to form [2+3] salicylimine cage compounds. Investigations on the chiral self-sorting revealed that while entropy favors narcissistic self-sorting in solution, selective social self-sorting can be achieved by exploiting the difference in solubility between the homochiral and heterochiral cages. Gas sorption measurements further showed that seemingly small structural differences can have a significant impact on the surface area of microporous covalent cage compounds.

Aromatic C-nitroso compounds (Ar-N═O) and related species have a rich chemical history, and they continue to interest researchers in many fields. Among the most distinctive and puzzling properties of these compounds is their ability to dimerize reversibly to form azodioxy compounds. The present review subjects this intriguing phenomenon to comprehensive analysis. All aspects of the subject are examined in detail, including the structures of monomeric and dimeric forms, the mechanism of dimerization, features that favor or disfavor dimerization, thermodynamic and kinetic factors, dimerization under specific conditions (including in solution, in the solid state, and on surfaces), and the special associative behavior of dinitroso and polynitroso compounds. By summarizing the current state of knowledge, the review promises to spur further advances in the evergreen field of C-nitroso chemistry, including the discovery of new ways to exploit the reversible dimerization of nitrosoarenes.

The strategy of chirality-assisted synthesis, which makes use of enantiomerically pure building blocks that are designed to associate in a single geometric orientation, was applied to synthesize an octameric hydrogen-bonded capsule with a cavity volume of 2300 Å . This cube-shaped capsule forms even host-guest complexes with tetraalkylammonium ions, and accommodates the large tetrahexadecylammonium cation in its cavity. The use of an enantiopure building block was shown to be highly beneficial for capsule formation, whereas its racemate also generates a large amount of ill-defined aggregates in solution and crystallizes as a hydrogen-bonded network.

We describe a simple way to build giant macrocyclic hydrocarbons by the reversible formation of carbon-carbon bonds. Specifically, extended spirobifluorene-substituted derivatives of Wittig's hydrocarbon were synthesized and found to undergo oligomerization, giving the largest hydrocarbon that has been crystallized and characterized by X-ray diffraction to date.