Molecules in solution tend to interact, both with identical molecules (oligimerization) and different ones (intermolecular forces and coordination). With each new association additional molecules with distinct spectroscopic signals appear. While novel configurations may be characterizable upon isolation, an equilibrium ensemble of molecules can also be studied by modeling spectrophotometric titrations. By properly varying the composition and measuring spectroscopic output for the entire range, the data can then be analyzed via equilibrium-restricted factor analysis. This powerful mathematical tool not only leads to the determination of the spectroscopic signature for each distinct absorber that exists during the course of the titration, but also yields the binding constants for each of the self-assembly events. This presentation will demonstrate the applicative breadth of such in situ characterizations by highlighting the self-assembly of several coordinatively-bonded supramolecular structures (grid, tetrahedron, and cube), as well as the oligimerization of methylene blue in aqueous solution.

What's going on in that solution? Characterizing the ensembles of molecules in complicated chemical solutions

244th National Meeting (2012)

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