“…These data are summarized in Tables and . HDA and PSA multilayers formed using Hf 4+ are essentially identical to those synthesized using Zr 4+ , and this result is fully consistent with the work reported by the Page group using Hf 4+ in the construction of bisphosphonate layered materials …”
We report on the growth of oriented multilayer assemblies where the layers are connected through
coordination to Zr4+ and Hf4+ ions. Layer orientation is achieved by asymmetric coordination at each layer.
We demonstrate R−O−PO3
2-−M4+−-O3S−R and R−O−PO3
2-−M4+−-O2C−R directional coordination
in multilayer assemblies. The synthetic approach to the formation of oriented multilayers is to use a
ω-hydroxyalkanoic acid or a ω-hydroxyalkanesulfonic acid in combination with phosphorylation chemistry
at the hydroxyl group to activate the interface at each step, allowing for the growth of additional, oriented
layers. The resulting interface is resistant to chemical attack, and Fourier transform IR data reveal only
limited order of the aliphatic portions of the layers.
“…These data are summarized in Tables and . HDA and PSA multilayers formed using Hf 4+ are essentially identical to those synthesized using Zr 4+ , and this result is fully consistent with the work reported by the Page group using Hf 4+ in the construction of bisphosphonate layered materials …”
We report on the growth of oriented multilayer assemblies where the layers are connected through
coordination to Zr4+ and Hf4+ ions. Layer orientation is achieved by asymmetric coordination at each layer.
We demonstrate R−O−PO3
2-−M4+−-O3S−R and R−O−PO3
2-−M4+−-O2C−R directional coordination
in multilayer assemblies. The synthetic approach to the formation of oriented multilayers is to use a
ω-hydroxyalkanoic acid or a ω-hydroxyalkanesulfonic acid in combination with phosphorylation chemistry
at the hydroxyl group to activate the interface at each step, allowing for the growth of additional, oriented
layers. The resulting interface is resistant to chemical attack, and Fourier transform IR data reveal only
limited order of the aliphatic portions of the layers.
“…The low solubility of the complex formed between phosphonates and several metal ions makes the structures especially robust, in contrast to Langmuir−Blodgett layers, which are characterized by weak interlayer associations. Zirconium phosphonate (ZP) layered complexes are most common, but other metal ions have been used as well. ,, The structures are built up one layer at a time with control over the specific molecular identity of each layer, affording exquisite control over the chemical, electrical, or optical properties of each layer and, consequently, of the entire film. 1 Structures of Oligobisphosphonates Used in This Work: (a) 2,2‘-Bithiophene-5,5‘-diylbis(phosphonic acid) (BDP); (b) 2,2‘:5‘,2‘‘:5‘‘,2‘‘‘-Quaterthiophene-5,5‘‘‘-diylbis- (phosphonic acid) (QDP); (c) 1,12-Dodecanediylbis- (phosphonic acid) (DDBPA); (d) 1,6-Hexanediylbis- (phosphonic acid) (HBPA)…”
Section: Introductionmentioning
confidence: 99%
“…( complexes are most common, but other metal ions have been used as well. 23,38,39 The structures are built up one layer at a time with control over the specific molecular identity of each layer, affording exquisite control over the chemical, electrical, or optical properties of each layer and, consequently, of the entire film. One application for which three-dimensional, layer-by-layer control of multilayer structure could potentially be useful is in optical information storage.…”
We report on the lifetime and motional dynamics of Zirconium
Phosphonate (ZP) monolayers
containing oligothiophene chromophores in a range of concentrations.
Monolayers were formed on fused
silica substrates and on a 15 Å oxide layer formed on crystalline
Si(100) substrates. For both interfaces, the
fluorescence lifetime behavior of the chromophores is identical and
does not depend on chromophore
concentration within the monolayer. Transient anisotropy
measurements reveal that, for both substrates, the
chromophores are oriented at ∼35° with respect to the surface
normal. For monolayers formed on silica,
there is no evidence for chromophore motion, while motion is seen for
monolayers formed on silicon. Despite
the substantial similarity between the two families of monolayers, the
surface roughness of the primed silicon
substrate allows for greater motional freedom of the chromophores in
the monolayers. We discuss these findings
in the context of the differences in substrate surface roughness and
domain sizes as measured by atomic force
microscopy (AFM).
“…One goal of the work we present here is to extend the lock-and-key strategy beyond the organic systems we have studied previously 10-13 to include inorganic systems. Understanding the aqueous chemistry of zirconium is also a matter of practical significance in the construction of robust multilayer assemblies. − We have measured fluorescence lifetimes and rotational diffusion dynamics of the probe molecule PCA in solutions of Zr 4+ “aged” between 0 and 110 h to understand the limit of structural information that can be obtained using the lock-and-key strategy. Lifetimes were found to decrease with solution age, and the rotational diffusion behavior of PCA in these solutions reveals that growth of zirconium hydrous polymers occurs until they approach an upper size limit.…”
We report on the hydrolytic polymerization of zirconium in aqueous solution using the transient optical response
of the fluorescent molecule 1-pyrenecarboxlyic acid (PCA) as a probe. We have measured the fluorescence
lifetimes and rotational diffusion dynamics of PCA in “aged” aqueous solutions of tetravalent zirconium to
understand the ability of fluorescent probes to report on the structural aspects of hydrous metal oxide self-assembly. The degree of polymerization, and therefore the extent of solute organization, is controlled by
allowing the Zr4+ solutions to polymerize (age) for selected amounts of time at 85 °C. Fluorescence lifetimes
and reorientation times measured for PCA in zirconium solutions increase rapidly, approaching a constant
value after 30 h of aging. The data point to growth of polymers that achieve a maximum volume. The
reorientation data place limits on the size and shape of polymers and provide insight into the mechanism for
their growth.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
