Full Record

New Search | Similar Records

Author
Title DESIGN, SYNTHESIS, AND CHARACTERIZATION OF INDANE 2,5-DIKETOPIPERAZINES FOR LIQUID CRYSTAL APPLICATIONS
URL
Publication Date
Date Accessioned
Degree Level doctoral
University/Publisher University of Arizona
Abstract Non-covalent interactions are of great importance in biology, chemistry, and material sciences. Although much information about different types of non-covalent interactions is available, incorporating them in a molecular design to generate a molecule that can undergo association to form a molecular assembly with bulk properties of interest is a challenge. To understand and harness intermolecular interactions, we have designed an indane 2,5-diketopiperazine (DKP) scaffold. Crystal engineering studies with this scaffold show that the molecules assemble into one dimensional tapes via reciprocal amide hydrogen bonds, tapes assemble into two dimensional sheets via arene-arene interactions, and sheets assemble into three dimensional solids via van der Waals contacts. A series of tetraalkoxy-substituted DKPs previously investigated exhibited liquid crystalline behavior. A new class of DKPs with one alkoxy substituent, rather than two, on each benzene ring has been synthesized. Thermochemical studies of the new DKPs by differential scanning calorimetry and polarized optical microscopy show that they are not liquid crystalline as expected. However, in the process of making the DKPs, conformationally constrained tyrosine analogues, (R)- and (S)-5-hydroxy-2-aminoindan- 2-carboxylic acids, were prepared by chromatographic separation of diastereomeric dipeptide derivatives formed from N-Boc-L-phenylalanine. Absolute configurations were assigned by X-ray crystallographic analysis. The series of tetraalkoxy-substituted DKPs showed a remarkable trend in freezing point. The freezing point for the series decreases with an increase in alkyl chain length. To understand the relationship between the crystal packing interactions and the freezing point trend, a study of the association of DKPs in solution by NMR was initiated. An Nmethylated 2,5-diketopiperazine was previously synthesized and studied by NMR using chloroform as solvent to obtain equilibrium constants for self association. Attempted multi-step syntheses of a more lipophilic N-3,7-dimethyloctyl 2,5-diketopiperazine, which was expected to have solubility in non-interfering solvents such as carbon disulfide, benzene, and carbon tetrachloride, failed. In response, a direct and concise method for accessing N-alkyl DKPs was developed, and an N-decyl 2,5-diketopiperazine was synthesized. X-ray crystallographic analysis of the N-decyl 2,5-diketopiperazine reveals formation of dimers via hydrogen bonding in the solid state.
Subjects/Keywords Indane 2,5-diketopiperazines; Liquid crystals; Chemistry; Crystal engineering; Hydrogen bonding
Contributors Mash, Eugene A. Jr (advisor); Glass, Richard S. (committeemember); Loy, Douglas A. (committeemember); Aspinwall, Craig A. (committeemember); Zheng, Zhiping (committeemember); Mash, Eugene A. Jr. (committeemember)
Language en
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.
Country of Publication us
Record ID handle:10150/202756
Repository arizona-diss
Date Retrieved
Date Indexed 2020-04-23
Issued Date 2011-01-01 00:00:00

Sample Search Hits | Sample Images

…122 Ethyl (R)-2-amino-5-methoxyindan-2-carboxylate [(R)-76]. ......................... 123 (2R,5ʹS)-5ʹ-Benzyl-5-bromo-6-methoxyspiro[indane-2,2ʹ-piperazine]-3ʹ,6ʹdione [(R,S)-77]…

…molecule that can undergo association to form a molecular assembly with bulk properties of interest is a challenge. To understand and harness intermolecular interactions, we have designed an indane 2,5-diketopiperazine (DKP) scaffold. Crystal…

…Scheme 1.5. Symmetrical cycloalkyl substituted DKPs studied by Whitesides and coworkers.42 32 Figure 1.6. Designed 2,5-diketo-1,4-piperazine molecular scalfold 32.6, 7 Indane 2,5-diketopiperazine 33 (Scheme 1.6) has been an attractive…

.