title: Synthesis of Catecholate Ligands with Phosphonate Anchoring Groups.
abstract: New catecholate ligands containing protected phosphonate anchoring groups in the 4-position of the catecholate ring were synthesized. The catechol 4-diethoxyphosphorylbenzene-1,2-diol, ((Et)phoscat)H2, was prepared in three steps from pyrocatechol; whereas, the catechol 4-(diethoxyphosphorylmethyl)benzene-1,2-diol, ((Et)Bnphoscat)H2, containing a methylene spacer between the catecholate ring and phosphonate anchor, was prepared from protocatechuic acid in six linear steps. Both catechol derivatives were further elaborated to their trimethylsilyl-protected counterparts to facilitate their binding to nanocrystalline metal oxides. Electronic spectroscopy and cyclic voltammetry were used to probe the electronic properties of the phosphonate-functionalized catecholates in charge-transfer complexes of the general formula (catecholate)Pd(pdi) (pdi = N,N'-bis(mesityl)phenanthrene-9,10-diimine). These studies show that attachment of the phosphonate anchor directly to the 4-position of the ((Et)phoscat)(2-) ligand significantly perturbs the donor ability of the catecholate ligand; however, incorporation of a single methylene spacer group in ((Et)Bnphoscat)(2-) helps to isolate catecholate from the electron-withdrawing phosphonate group.
authors.affiliation: †Department of Chemistry, University of California, Irvine, California 92697, United States.
authors.forename: Elaine
authors.initials: E
authors.lastname: Seraya
authors.affiliation: ‡Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697, United States.
authors.forename: Zhongyue
authors.initials: Z
authors.lastname: Luan
authors.affiliation: †Department of Chemistry, University of California, Irvine, California 92697, United States.|‡Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697, United States.
authors.forename: Matt
authors.initials: M
authors.lastname: Law
authors.affiliation: †Department of Chemistry, University of California, Irvine, California 92697, United States.
authors.forename: Alan F
authors.initials: AF
authors.lastname: Heyduk