Erasable Coordination Polymer Multilayers on Gold

Patterned polymeric multilayered assemblies through hydrogen bonding and metal coordination

Patterned polymeric multilayered assemblies were formed using a combination of metal coordination and hydrogen bonding interactions. We proved that the hydrogen bonding interaction between diamidopyridine and thymine can be employed for polymeric multilayer assemblies. We then combined this strategy along with a second supramolecular interaction, metal coordination. These interactions proved to be orthogonal to one another on the surface, making each discrete region individually responsive to external stimuli.

Functional soft materials from metallopolymers and metallosupramolecular polymers

Synthetic polymers containing metal centres are emerging as an interesting and broad class of easily processable materials with properties and functions that complement those of state-of-the-art organic macromolecular materials. A diverse range of different metal centres can be harnessed to tune macromolecular properties, from transition- and main-group metals to lanthanides. Moreover, the linkages that bind the metal centres can vary almost continuously from strong, essentially covalent bonds that lead to irreversible or 'static' binding of the metal to weak and labile, non-covalent coordination interactions that allow for reversible, 'dynamic' or 'metallosupramolecular', binding. Here we review recent advances and challenges in the field and illustrate developments towards applications as emissive and photovoltaic materials; as optical limiters; in nanoelectronics, information storage, nanopatterning and sensing; as macromolecular catalysts and artificial enzymes; and as stimuli-responsive materials. We focus on materials in which the metal centres provide function; although they can also play a structural role, systems where this is solely their purpose have not been discussed.

Synergism in multicomponent self-propagating molecular assemblies

Multicomponent self-propagating molecular assemblies (SPMAs) have been generated from an organic chromophore, a redox-active polypyridyl complex, and PdCl(2). The structure of the multicomponent SPMA is not a linear combination of two assemblies generated with a single molecular constituent. Surface-confined assemblies formed from only the organic chromophore and PdCl(2) are known to follow linear growth, whereas the combination of polypyridyl complexes and PdCl(2) results in exponential growth. The present study demonstrates that an iterative deposition of both molecular building blocks with PdCl(2) results in an exponentially growing assembly. The nature of the assembly mechanism is dictated by the polypyridyl complex and overrides the linear growth process of the organic component. Relatively smooth, multicomponent SPMAs have been obtained with a thickness of ∼20 nm on silicon, glass, and indium-tin oxide (ITO) coated glass. Detailed information of the structure and of the surface-assembly chemistry were obtained using transmission optical (UV/Vis) spectroscopy, ellipsometry, atomic force microscopy (AFM), synchrotron X-ray reflectivity (XRR), and electrochemistry.

Supramolecular functionalization of electron-beam generated nanostructures

Electron-beam lithography was used to pattern poly(styrene-co-(methyldiaminotriazine) styrene) (PS-Triaz). These polymer nanopatterns were utilized as molecular scaffolds for assembling complementary thymine-functionalized CdSe-ZnS quantum dots (Thy-QDs) via three-point hydrogen-bonding molecular recognition. This interaction was very specific, with N-methyl thymine-functionalized QDs (MeThy-QDs) not depositing on the surfaces. The "lock and key" specificity of the assembly is mirrored in the disassembly process, where complete removal of the QD was observed using a competing thymine guest.

Bridged coordination polymer multilayers with tunable properties

Coordination multilayers consisting of Pd(II) pincer-type complexes and poly(vinyl pyridine) were synthesized and characterized. Film properties were found to be dependent on and could be tuned by varying bath deposition concentrations, polymer molecular weight, and solution additives that compete with binding. Generally, smoother, thinner films were obtained with lower poly(vinyl pyridine) deposition bath concentrations. Likewise, film thickness and roughness could be reduced by employing a higher-molecular-weight poly(vinyl pyridine). Film properties could also be influenced by using acetonitrile as a solution additive, effectively driving the binding equilibrium slightly toward the free species.