Direction-dependent secondary bonds and their stepwise melting in a uracil-based molecular crystal studied by infrared spectroscopy and theoretical modeling
Chemical Physics Letters
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Szekrényes, Z., Nagy, P., Tarczay, G., Maggini, L., Bonifazi, D., & Kamarás, K. (2018). Direction-dependent secondary bonds and their stepwise melting in a uracil-based molecular crystal studied by infrared spectroscopy and theoretical modeling. Chemical Physics Letters, 691 163-168. https://doi.org/10.1016/j.cplett.2017.11.006
Three types of supramolecular interactions are identified in the three crystallographic directions in crystals of 1,4-bis[(1-hexylurac-6-yl)ethynyl]benzene, a uracil-based molecule with a linear backbone. These three interactions, characterized by their strongest component, are: intermolecular double H-bonds along the molecular axis, London dispersion interaction of hexyl chains connecting these linear assemblies, and $\pi$--$\pi$ stacking of the aromatic rings perpendicular to the molecular planes. On heating, two transitions happen, disordering of hexyl chains at 473 K, followed by H-bond melting at 534 K. The nature of the bonds and transitions was established by matrix-isolation and temperature-dependent infrared spectroscopy and supported by theoretical computations.
External DOI: https://doi.org/10.1016/j.cplett.2017.11.006
This record's URL: https://www.repository.cam.ac.uk/handle/1810/285937