Rajbanshi, Arbin2010-05-042010-05-042010-05-04http://hdl.handle.net/2097/3879Supramolecular synthesis relies upon the creative and rational use of the common intermolecular forces and a proper understanding of these forces is critical for design and assembly of molecular building blocks into extended networks. The strength of seven substituted pyridines as hydrogen-bond acceptors was probed using a series of fifteen mono/dicarboxylic acids to demonstrate the interrelationship between the charge on the substrate and its ability to form co-crystals/salts. The higher charge in the acceptor led to proton transfer (100% yield) from the hydrogen bond donor to give a salt, whereas the lower charge led to co-crystals. This specificity observed for small molecules was extended to an investigation of selectivity in ditopic molecules. A series of nineteen hydrogen-bond donors, including fifteen carboxylic acids and four cyanoximes, were tested for binding preferences against ten ditopic ligands with variable charges. The overall supramolecular yield of 82% (9/11) proved a high degree of reliability in terms of best acceptor/donor approach, hence establishing the efficiency of the calculated charges as a guideline for molecular recognition processes. Solubility and thermal properties of pharmaceutical drug mimics were altered via formation of co-crystals/salts. The ligands and their co-crystals/salts with five even-chain dicarboxylic acids were synthesized and their comparative solubility in pure water and in pH 6.8 buffer solution measured. Solubility enhancement to a degree of 9x is observed for pharmaceutical drug haloperidol, whereas decrease in solubility down to 81% is achieved for 2-amino-5-(3-pyridyl)pyrimidine (which has agrochemical significance). Also the thermal and solubility behavior of these co-crystals were shown to reflect the properties of their parent co-crystallizing agents, allowing for a modulation of physical properties. Finally, the specificity and selectivity of the intermolecular interactions observed for small molecules were applied in the synthesis of hydrogen and halogen-bonded capsules. Several resorcinarene-based cavitands were synthesized and their upper rim decorated with acetamidopyridyl, aminopyrazinyl, 3-pyridyl, and 4-pyridyl moieties with hydrogen and halogen-bonding potentials. A homomeric hydrogen-bonded capsule was formed with self-assembly of acetamidoethynylcavitand via N-H···O=C interactions, whereas a heteromeric halogen-bonded capsule, the very first of its kind, was formed with N···I halogen-bonded interaction between 3-pyridylcavitand and tetrafluoroiodo-substituted calixarene.en-US© the author. This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).http://rightsstatements.org/vocab/InC/1.0/co-crystalssupramolecular chemistrymolecular capsulescavitandssolubilitymolecular recognitionDissertationChemistry, Organic (0490)