Inorganic monolayers formed at an organic template: a Langmuir-Blodgett route to monolayer and multilayer films of zirconium octadecylphosphonate

Metal Phosphonates Applied to Biotechnologies: A Novel Approach to Oligonucleotide Microarrays

“…An inorganic system that we have found to meet these requirements is a series of thin films of metal organophosphonates and organophosphates. [41][42][43][44][45][46][47] In the solid-state, many examples form layered structures with organic sheets separating continuous inorganic networks of metal ions coordinated by the phosphonate or phosphate oxygen atoms. [48] An example is the layered Zr(O 3 PC 6 H 5 ) 2 shown in Figure 4.…”

“…This surface can subsequently be used to adsorb another layer of an organophosphonate or phosphate that deposits as a type of self-assembled monolayer. [41] Our groups have used this chemistry to form monolayer films of organophosphonates with organic groups ranging from simple alkanes [41] to azobenzene, [45] tetrathiafulvalene, [55] phenoxy and biphenoxy groups, [43] and porphyrins. [46] The zirconium phosphonate-modified surfaces can be prepared in different ways, but often involve binding of Zr 4 + ions to phosphorylated groups deposited onto silica [50,51,54,[56][57][58][59][60][61] or gold ( Figure 6).…”

“…2005, 11, 1980 -1988 www.chemeurj.org 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim ated on hydrophobic supports by using Langmuir-Blodgett (LB) methods. [41][42][43][44][45][46] The LB process begins with an octadecylphosphonic acid (ODPA) Langmuir monolayer that is deposited onto the hydrophobic solid support in such a way that the hydrophilic acid group (PO 3 H 2 ) is directed away from the support (Figure 7). [41,42] The substrate is then removed from the LB trough and exposed to a solution of Zr 4 + ions that bind to give a monolayer of the zirconated octadecylphosphonic acid (ODPA-Zr).…”

“…The same situation arises in the zirconated LB films. The strongly binding zirconium ions cross-link the original monolayer, providing a well-defined interface of zirconium phosphonate sites [41,42] that sticks strongly to the surface, because it is no longer a traditional LB film of individual molecules physisorbed to the surface but rather a network or monolayer tape in which adhesion comes from the sum of all molecules in a cross-linked array. The zirconium phosphonate films are not soluble in organic solvents, and dissolve in water only below pH 1.…”

Microscopic Frictional Response of Sodium Oleate Self-Assembled on Steel

“…The packing density of the self-assembled monolayer is indicated by the FWHM (full width at half maxima). Here the FWHM for the methylene group is found to be 18.5 cm -1 , which indicates that a reasonably closed packed monolayer has formed [31]. Figure 2 shows the friction of the SAM to increase nonlinearly with load to reach a peak of about 8 nN at 17 nN normal load and then to decline with increasing load to a value of about 4-5 nN when the normal load is in the 30-40 nN regime.…”