| A series of stereodynamic transition metal/organic ligand complexes are described. Tripodal ligands were prepared via multi-step syntheses, and correlations between triggered conformational changes and optical properties of the metal complexes were studied by a wide variety of spectroscopic techniques. Generally, the ligands were synthetic analogs of the compound tris(2-pyridylmethyl)amine (TPA).; A dynamic NMR study of 1-(quinolin-2-yl)-N,N-bis(quinolin-2-ylmethyl)ethanamine (MeTQA) provided clear evidence that, although Cu(II) is coordinated by all three quinolines of the ligand, Cu(I) only coordinates the arm containing the methyl group and one of the two other arms which are in exchange. To achieve more control over the dynamic behavior, a trans-piperidine tripodal ligand was prepared by asymmetric synthesis. This compound showed very interesting "on-off" behavior as a chiroptical switch: the Cu(I) and Cu(II) states of the complex showed dramatically different geometries and resulted in strongly different circular dichroism spectra. In this new complex, the Cu(I) state has one dissociated quinoline arm, but, unlike the McTQA complexes, the dissociated arm is not in rapid exchange on the NMR timescale.; Chiral TPA analog synthesis was studied as a means to determine absolute configuration of primary amines. Using simple derivatization as described for the synthesis of chiral tripodal ligands in combination with conformational analysis and exciton-coupled circular dichroism studies of its coordination complexes, it was possible to assign the absolute configuration of the starting amine.; The tripodal ligands generally showed poor water solubility. Several tris(3,4,5-trialkoxy-6-phenyl-2-pyridylmethyl)amine ligands were prepared and were found to be soluble in both organic solvents and water. Interestingly, the ZnII coordination complex of these ligands gave an excimer fluorescence spectrum in acetonitrile, providing a probe for zinc sensing.; Lastly, a biological molecular switch was investigated involving the remarkable metabolic conversion of an enzyme inhibitor to an activator. Stimulated by the discovery that p-aminobenzoic acid (PABA) inhibits the production of melanin, the kinetics studies of tyrosinase in the presence of PABA indicated classical non-competitive inhibition for PABA. However, its major metabolite, p-aminohippuric acid (PAHA) was found to increase the rate of DOPAchrome formation. |
