Gram-scale synthesis of two-dimensional polymer crystals and their structure analysis by X-ray diffraction

Abstract

The rise of graphene, a natural two-dimensional polymer (2DP) with topologically planar repeat units, has challenged synthetic chemistry, and has highlighted that accessing equivalent covalently bonded sheet-like macromolecules has, until recently, not been achieved. Here we show that non-centrosymmetric, enantiomorphic single crystals of a simple-to-make monomer can be photochemically converted into chiral 2DP crystals and cleanly reversed back to the monomer. X-ray diffraction established unequivocal structural proof for this synthetic 2DP, which has an all-carbon scaffold and can be synthesized on the gram scale. The monomer crystals are highly robust, can be easily grown to sizes greater than 1 mm and the resulting 2DP crystals exfoliated into nanometre-thin sheets. This unique combination of features suggests that these 2DPs could find use in membranes and nonlinear optics.

Vertical 2D Heterostructures

“…The quest for dimensionally reduced graphene analogs has reached almost all corners of the periodic table, and the available toolbox of nanosheet materials can be pragmatically (rather than systematically) classified into the following categories: graphene, chalcogenides, oxides and hydroxides, group IV semiconductors and Zintl phases (9, 10), ceramics and nitrides (11)(12)(13), and soft 2D materials such as polymers and coordination networks (14,15). For a comprehensive treatment of the 2D building blocks that are available for the assembly of heterostructures, the reader is referred to recent reviews on the topic as well as related reviews within this volume (4,(16)(17)(18)(19)(20).…”

Interplay Between Mechanochemistry and Sonochemistry

“…If all-carbon graphene has so far attracted enormous attention in mass media, the fact that polymerized organic crystals can also be exfoliated to create two-dimensional sheets should likewise open a new age of innovation in materials design. The subject is in its infancy, but two recent papers in Nature Chemistry will pave the way for these exciting 2D-polymers [72,73]. Both studies exploit the photopolymerization of single crystals, in particular anthracene-based monomers, where photochemical dimerization is facilitated by aromatic unit stacking.…”

The plastics revolution: how chemists are pushing polymers to new limits

“…Using the same approach, Schlüter and Benjamin King, head of the chemistry department at the University of Nevada, Reno, have independently produced different types of 2D polymer 9,10 . Now collaborators, the two researchers hope that they will soon be able to make these sheets in kilogram batches, easily enough to distribute samples to research groups around the world.…”