Hydrogen-bonded supramolecular polymers: A literature review

Supramolecular polymer science has matured into a technology ready for industrial application. This review begins with an overview of the principles underlying self-assembly of supramolecular polymers. Polymers developed over the past decade are discussed, with emphasis placed on stable hydrogen bonded structures that exhibit useful material properties. The commercial potential of such supramolecular polymers is also considered.     

Hydrogen-bonded nanotubes as a model for DNA transcription

Using the energy asymmetries in the hydrogen-bonded structures, the model is formulated explaining melting of DNA double chain and also explaining further decay of only one of the obtained single chains. The model is similar to the Scott's model of alpha-helix, where the spiral is substituted with interacting discs. The explanation of mentioned DNA transformation is based on the estimate of free energy of discs with an even number of hydrogen bonds, and an estimate of melting point temperature for the subsystem of odd index fibers and transition temperature of the subsystem of even index fibers.     

Flexible Luminescent Hydrogen-bonded Organic Framework for the Separation of Benzene and Cyclohexane

A nonplanar phenothiazine derivative with three cyano moieties (PTTCN) is designed and synthesized to achieve functional crystals for absorptive separation of benzene and cyclohexane. PTTCN can crystallize into two kinds of crystals with different fluorescence colors in different solvent systems. The molecules in two crystals are in different stereo isomeric forms of nitrogen, quasi axial (ax), and quasi equatorial (eq). The crystals with blue fluorescence in ax form may selectively adsorb benzene by a single-crystal-to-single-crystal (SCSC) transformation, but separated benzene from a benzene/cyclohexane equimolar mixture with a low purity of 79.6%. Interestingly, PTTCN molecules with eq form and benzene co-assembled to construct a hydrogen-bonded framework (X-HOF-4) with S-type solvent channels and yellow-green fluorescence, and can release benzene to form nonporous guest-free crystal under heating. Such nonporous crystals strongly favor aromatic benzene over cyclohexane and may selectively reabsorb benzene from benzene/cyclohexane equimolar mixture to recover original framework, and the purity of benzene can reach ≈96.5% after release from framework. Moreover, reversible transformation between the nonporous crystals and the guest-containing crystals allows the material to be reused.