Abstract/Details

Crystallization of polar organic materials from solution


2003 2003

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Abstract (summary)

The ability of a chemical compound to crystallize in a variety of shapes has sparked the imagination of scientists for many years. Particularly since the external shape of a crystal is associated with some of the most important characteristics of the crystalline product, including chemical stability, solubility, processing characteristics and more.

Models for predicting crystal shape use geometrical rules and energy calculations of the interactions between the building blocks of the crystal, but often ignore the environment in which the crystal grows. Systems that contain polar molecules tend to be influenced by the environment, since polar molecules interact with polar solvents, and this interaction influences the final shape.

Three of the most prominent models for predicting crystal shape: the Bravais-Friedel-Donnay-Harker (BFDH) model, the equilibrium model, and the attachment energy model, have been explored in this thesis. Two major kinetic theories: two dimensional nucleation and screw dislocation have been explored as well. The latter, also known as the BCF growth mechanism, serves as a basis for a proposed model to predict the shape of polar organic crystals grown from solution. The model accounts for the solute-solvent interactions at the interface by using face specific and solvent specific properties. Polar solute-polar solvent interactions were incorporated using a method developed by Fowkes. A description of the size and the nature of the intermolecular interactions along the different growth directions is a prerequisite for application of the model. Using this model, the shapes of urea grown from polar solvents was successfully predicted.

In an effort to extend the functionality of this model, amino acids were selected as model systems. The selection of a reliable force field, the description of charge distribution and the nature of the growth unit were found to be primary factors in modeling the interactions between highly polar organic molecules. The method proposed to determine these factors involves quantitative measures, as the comparison of the calculated lattice energy to the sublimation enthalpy, and heuristic rules which are based on experience.

The shapes of α-glycie and L-alanine grown from aqueous solution were successfully predicted and compared with experimental results.

Indexing (details)


Subject
Organic chemistry;
Pharmacology;
Chemical engineering
Classification
0490: Organic chemistry
0491: Pharmacology
0542: Chemical engineering
Identifier / keyword
Applied sciences, Pure sciences, Amino acids, Crystallization, Polar organic materials
Title
Crystallization of polar organic materials from solution
Author
Bisker-Leib, Vered
Number of pages
167
Publication year
2003
Degree date
2003
School code
0118
Source
DAI-B 64/02, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Advisor
Doherty, Michael F.
University/institution
University of Massachusetts Amherst
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3079595
ProQuest document ID
287934079
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/287934079
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