Persistent Link:
http://hdl.handle.net/10150/612051
Title:
Crystal Engineering with Piperazinediones
Author:
Khanal, Pitambar
Issue Date:
2016
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Embargo:
Release after 15-Jun-2016
Abstract:
Non covalent interactions are valuable tools for crystal engineering. Hydrogen bonding often plays a central role for molecular association among possible non covalent interactions. Together with hydrogen bonding, arene-arene interactions and van der Waals interactions can control crystal assembly. Understanding non covalent interactions permits the design of molecules whose functionalities can interact non covalently so that molecules will pack in a predicted fashion. For two decades Prof. Mash's group has been studying crystal packing based on a piperazinedione core scaffold which can have three orthogonal non covalent interactions and lead to controlled three dimensional crystal packing. Alkoxy-substituted piperazinediones were previously studied for crystal packing and liquid crystal properties. It was found that alkoxy piperazinediones pack in three dimesions as designed and exhibit interesting thermochemical properties. Given that small changes in structure can cause large changes in packing and liquid crystal properties, the replacement of alkoxy groups with alkyl groups in molecules provides an opportunity to investigate the role of oxygen in crystal packing and liquid crystal properties. A series of alkyl piperazinediones was synthesized in a convergent way where an intermediate tetrabromide was converted into a series of tetra alkyne piperazinediones, then into tetra alkyl piperazinediones. This approach overcame limitations in the synthesis of alkoxy piperazinediones, where every target molecule requires 10 to 11 steps starting from 2,3-dimethylbenzene-1,4-diol (Scheme 2.1). Crystal structure analyses were done for three different piperazinediones. It appears that crystal packing of alkyl piperazinediones mimics that of alkoxy piperazinediones.
Type:
text; Electronic Dissertation
Keywords:
Organic Synthesis; Piperazinediones; Chemistry; Crystal Engineering
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Chemistry
Degree Grantor:
University of Arizona
Advisor:
Mash, Eugene A., Jr.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleCrystal Engineering with Piperazinedionesen_US
dc.creatorKhanal, Pitambaren
dc.contributor.authorKhanal, Pitambaren
dc.date.issued2016-
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.description.releaseRelease after 15-Jun-2016en
dc.description.abstractNon covalent interactions are valuable tools for crystal engineering. Hydrogen bonding often plays a central role for molecular association among possible non covalent interactions. Together with hydrogen bonding, arene-arene interactions and van der Waals interactions can control crystal assembly. Understanding non covalent interactions permits the design of molecules whose functionalities can interact non covalently so that molecules will pack in a predicted fashion. For two decades Prof. Mash's group has been studying crystal packing based on a piperazinedione core scaffold which can have three orthogonal non covalent interactions and lead to controlled three dimensional crystal packing. Alkoxy-substituted piperazinediones were previously studied for crystal packing and liquid crystal properties. It was found that alkoxy piperazinediones pack in three dimesions as designed and exhibit interesting thermochemical properties. Given that small changes in structure can cause large changes in packing and liquid crystal properties, the replacement of alkoxy groups with alkyl groups in molecules provides an opportunity to investigate the role of oxygen in crystal packing and liquid crystal properties. A series of alkyl piperazinediones was synthesized in a convergent way where an intermediate tetrabromide was converted into a series of tetra alkyne piperazinediones, then into tetra alkyl piperazinediones. This approach overcame limitations in the synthesis of alkoxy piperazinediones, where every target molecule requires 10 to 11 steps starting from 2,3-dimethylbenzene-1,4-diol (Scheme 2.1). Crystal structure analyses were done for three different piperazinediones. It appears that crystal packing of alkyl piperazinediones mimics that of alkoxy piperazinediones.en
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectOrganic Synthesisen
dc.subjectPiperazinedionesen
dc.subjectChemistryen
dc.subjectCrystal Engineeringen
thesis.degree.namePh.D.en
thesis.degree.leveldoctoralen
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplineChemistryen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorMash, Eugene A., Jr.en
dc.contributor.committeememberHruby, Victor J.en
dc.contributor.committeememberNjardarson, Jonen
dc.contributor.committeememberMIller, Walter B, IIIen
dc.contributor.committeememberMash, Eugene A., Jr.en
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.