Ligand Metathesis in Surface-Bound Alkoxyzirconium Complexes. 2. Preparation of Alkanecarboxylate Complexes in Ultrahigh Vacuum

Electrochemically Active Surface Zirconium Complexes on Indium Tin Oxide

“…The stoichiometry of deposition of 1 onto ITO in ultrahigh vacuum (UHV) was found to be similar to that on other oxide surfaces examined. ,,,, Chemisorption involves protolytic loss of primarily one tert -butoxide ligand to give 2 ; a small amount of 2 ‘, formed from a second protonolysis step, may also be present at room temperature (by XPS: C/Zr [≈300 K] = 12.7; [≈430 K] = 10.1; for 2 , expected C/Zr = 12; for 2 ‘, expected C/Zr = 8) 21 (Scheme ). Reaction of analogues of either 2 or 2 ‘ with carboxylic acids gives dicarboxylates ( 3 and 3 ‘, respectively; Scheme ); apparently, reaction of species such as 3 with a third equivalent of carboxylic acid is sterically unfavorable …”

“…We had previously demonstrated that attachment of alkanecarboxylic acids to oxide surfaces could be stabilized against removal by evaporation or solvent wash-off by using zirconium alkoxide complex-derived interfaces. , We had also shown that a variety of ligand types can be introduced subsequently into the coordination sphere of the Zr by simple exchange of residual tert -butoxy ligands with a variety of carboxylic acids and phenols. ,, Thus, because 2 is easy to prepare, and because it is subject to ligand exchange with a variety of species, this methodology is versatile for rapid and variable surface modification of ITO electrodes.…”

“…We have previously exploited the reactivity of surface OH groups of metal oxides for surface functional group quantification and modification using organometallic reagents, − and we have reported that bonding of carboxylic acids to oxide surfaces can be stabilized using zirconium alkoxide complex-derived interfaces. , Because of the ease of ligand metathesis in these surface-bound alkoxides, they represent a versatile interface for formation of families of surface-bound materials from a common, easy-to-prepare precursor. ,, We now report that these synthetic methodologies can be used to bond a simple, electrochemically active ferrocenecarboxylate derivative to the ITO surface via ligand metathesis at Zr in a process that obviates tedious tethering group synthesis and attachment. Happily, we find that the Zr complex interface does not deleteriously affect the electrochemical behavior of the ligated ferrocenecarboxylate species.…”

“…16,17 Because of the ease of ligand metathesis in these surfacebound alkoxides, they represent a versatile interface for formation of families of surface-bound materials from a common, easy-to-prepare precursor. 16,18,19 We now report that these synthetic methodologies can be used to bond a simple, electrochemically active ferrocenecarboxylate derivative to the ITO surface via ligand metathesis at Zr in a process that obviates tedious tethering group synthesis and attachment. Happily, we find that the Zr complex interface does not deleteriously affect the electrochemical behavior of the ligated ferrocenecarboxylate species.…”

Enhanced Bonding of Alkanephosphonic Acids to Oxidized Titanium Using Surface-Bound Alkoxyzirconium Complex Interfaces

“…We have reported the use of surface zirconium complexes, which are prepared by reaction of zirconium alkoxides with surface hydroxyl groups, to enhance bonding between carboxylic acids and metal oxides or oxidized metal surfaces. − For example, we found that surface Zr η 2 -carboxylates 1 are more stable with regard to thermal desorption 1,2 or washing 3 than are adducts formed spontaneously by simple reaction of the carboxylic acid and the oxide surface. Alkanephosphonic acids are another broad class of organic acids which have been used to protect, lubricate, and enhance adhesion properties of the surface of substrates as diverse as steel, aluminum, and paper .…”