There is a good evidence in nature that most of the dynamic biological systems are self-assembled in water by differential solvation. The concept of gradually changing water solubility along a molecule, has been proposed to be differential solvation in our laboratories. For example, nucleic acid structure is composed of a nitrogenous base, a five-member sugar and a phosphate group. Each of these groups individually have different solubility in water. Accordingly, when dispersed in water, the molecules arrange themselves by taking this solubility demand into consideration and ordered arrangements rather than random accumulations are observed. In longer chain structures such as oligomers or polymers (i.e. DNA) this gradual change in solubility leads to the thermodynamically favored helical structure. By adopting the helical structure, the phosphate group, most soluble part of DNA structure, has the highest contact with the aqueous medium while the least soluble part, that is the nitrogenous base is hidden within the molecule. This also enables the nitrogenous bases to make hydrogen bonds with each other rather than water, which is also capable of making hydrogen bonds. With differential solvation, the latter is avoided and the double helix is established. With all these in mind, examining such a phenomena with simple molecules will prove this concept further. To do this, we designed dynamic systems which recognize and form regular supramolecular assemblies. Two sets of compounds were designed and synthesized; 1) compound has carboxylic acid at one end and a solvochromic compound on the other end which are connected to each other via ethylene glycol units, 2) compound has carboxylic acid at one end and a solvochromic compound on the other end which are connected to each other via alkyl chains. This presentation will describe the synthesis and assemblies of these two sets of compounds in water with NMR, DLS, fluorescence and UV-vis spectroscopy.

Differential solvation: Proof of concept by solvochromic and temperature-responsive properties of alkyl/triethylene glycol side chains

256th National Meeting (2018)

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