Studies of the packing of cocrystals of alkynoic acids with amine and pyridine acceptors

We have been successful in generating and determining the crystal structure of a new type of carboxylic acid cocrystal with a pyridine-based acceptor. In order to extend our work on the solid-state reactivity and crystal engineering of pyridine- or amine : carboxylic acid cocrystals, it seemed worthwhile to attempt to generate two-dimensional layer structures with van der Waals spacings between the layers. We decided to use an "extended" planar acceptor, viz., trans-1,2-bis(4-pyridyl)ethylene 1, with the expectation that the extended conjugation would promote the formation of planar arrays when cocrystals were synthesized with carboxylic acids.

We have synthesized a cocrystal with 4-pentynoic acid 2, and have just completed an X-ray structure determination. As can be seen, planar arrays indeed are formed!

Is this part of a bigger picture? We think so....when we synthesized cocrystals of 1 and 2-butynoic acid, CHCCOOH, it happened again:

Stay tuned for further developments.

This material is based upon work supported by the National Science Foundation under Grant No. DMR-0089257. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation (NSF).

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Bruce Foxman (