Hydrogen- and halogen-bond driven co-crystallizations: from fundamental supramolecular chemistry to practical materials science

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dc.contributor.author Widanalage Dona, Tharanga Kumudini Wijethunga
dc.date.accessioned 2015-11-10T14:20:06Z
dc.date.available 2015-11-10T14:20:06Z
dc.date.issued 2015-12-01 en_US
dc.identifier.uri http://hdl.handle.net/2097/20497
dc.description.abstract A series of co-crystallizations between four biimidazole based compounds with nine symmetric aliphatic di-acids and fifteen perfluorinated halogen-bond donors were carried out to determine if a MEPS based ranking can be used to effectively assign selectivity in hydrogen- and halogen-bond interactions. The results suggested that a simple electrostatic view provides a reliable tool for successfully implementing the practical co-crystal synthesis with desired connectivity. MEPS based selectivity guidelines for halogen-bond interactions were explored in co-crystallizations between twelve asymmetric ditopic acceptors and nine halogen-bond donors. If the difference between the two acceptor sites is below 35 kJ/mol, no selectivity was observed; above 65 kJ/mol halogen bond selectivity dominates and mid ΔE range was recognized as the grey area where predictions cannot be made. To examine competition between hydrogen and halogen bonds, five heteroaryl-2-imidazoles were co-crystallized with fifteen halogen-bond donors. It was found that halogen bonds prefer best the acceptor site, demonstrating that a suitably activated halogen-bond donor can compete with a strong hydrogen-bond donor. The benefits of ‘double activation’ for promoting halogen bond effectiveness was explored with nine haloethynylnitrobenzenes. The positive potential on halogen atoms was enhanced through a combination of an sp-hybridized carbon and electron-withdrawing nitro group(s). Iodoethynylnitrobenzenes were identified as the most effective halogen-bond donors reported to date and the compounds were exploited for the interaction preferences of nitro group and nitro⋯X-Csp interactions were identified as synthetic tools for energetic co-crystal assembly. A synthetic strategy for the deliberate assembly of molecular polygons was developed utilizing bifurcated halogen bonds constructed from N-oxides and complementary halogen-bond donors via co-crystallization. A convenient, effective, and scalable protocol for stabilizing volatile liquid chemicals with co-crystallization was achieved. Through the use of halogen-bonding, liquid iodoperfluoroalkanes were transformed into crystalline materials with low-vapor pressure, considerable thermal stability and moisture resistance. To stabilize the energetic compound ethylenedinitramine, a co-crystallization approach targeting the acidic protons was employed. Eight co-crystals were obtained and the acceptors were identified as supramolecular protecting groups leading to diminished reactivity and enhanced stability while retaining the desirable energetic properties. en_US
dc.language.iso en en_US
dc.publisher Kansas State University en
dc.subject Co-crystal en_US
dc.subject Halogen bond en_US
dc.subject Hydrogen bond en_US
dc.subject Crystal engineering en_US
dc.subject Supramolecular chemistry en_US
dc.subject Energetic co-crystal en_US
dc.title Hydrogen- and halogen-bond driven co-crystallizations: from fundamental supramolecular chemistry to practical materials science en_US
dc.type Dissertation en_US
dc.description.degree Doctor of Philosophy en_US
dc.description.level Doctoral en_US
dc.description.department Chemistry en_US
dc.description.advisor Christer B. Aakeroy en_US
dc.subject.umi Materials Science (0794) en_US
dc.subject.umi Molecular chemistry (0431) en_US
dc.subject.umi Organic Chemistry (0490) en_US
dc.date.published 2015 en_US
dc.date.graduationmonth December en_US


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