Post transition metal substituted Keggin-type POMs as thin film chemiresistive sensors for HO and CO detection.

Chemiresitive sensing allows the affordable and facile detection of small molecules such as HO and CO. Herein, we report a novel class of Earth-abundant post transition metal substituted Keggin polyoxometalates (POMs) for chemiresistive sensing applications, with conductivities up to 0.01 S cm under 100% CO and 65% Relative Humidity (RH).

Vesicles, fibres, films and crystals: A low-molecular-weight-gelator [Au(6-thioguanosine)]Cl which exhibits a co-operative anion-induced transition from vesicles to a fibrous metallo-hydrogel.

We describe a simple coordination compound of Au(I) and 6-thioguanosine, [Au(6-tGH)]Cl, that has a rich self-assembly chemistry. In aqueous solution, the discrete complex assembles into a supramolecular fibre and forms a luminescent hydrogel at concentrations above about 1 mM. Below this concentration, the macromolecular structure is a vesicle.

Hierarchical self-assembly in an RNA-based coordination polymer hydrogel.

An RNA-based coordination polymer is formed by the aqueous reaction of Cu ions with the thionucleoside enantiomer (-)6-thioguanosine, (6tGH). The resulting polymer, [Cu(μ-S-thioG)]1, has a one-dimensional structure based on a [Cu-S] core and undergoes extensive hierarchical self-assembly transforming from oligomeric chains → rod → cable → bundle through which a fibrous gel forms, that undergoes syneresis to form a self-supporting mass. The assembly involves the formation of helical cables/bundles and, in combination with the intrinsic photoemission of the polymer, results in the material exhibiting circularly polarised luminescence (CPL).

Circularly polarised luminescence in an RNA-based homochiral, self-repairing, coordination polymer hydrogel.

The aqueous equimolar reaction of Ag(i) ions with the thionucleoside enantiomer (-)6-thioguanosine, ((-)6tGH), yields a one-dimensional coordination polymer {Ag(-)tG} , the self-assembly of which generates left-handed helical chains. The resulting helicity induces an enhanced chiro-optical response compared to the parent ligand. DFT calculations indicate that this enhancement is due to delocalisation of the excited state along the helical chains, with 7 units being required to converge the calculated CD spectra.

Bottom-up device fabrication the seeded growth of polymer-based nanowires.

The bottom-up assembly of nanoelectronic devices from molecular building blocks is a target of widespread interest. Herein we demonstrate an seeded growth approach to produce a nanowire-based electrical device. This exploits the chemisorption of block terpolymer-based seed fibres with a thiophene-functionalised corona onto metal electrodes as the initial step.

Addressing the properties of "Metallo-DNA" with a Ag(i)-mediated supramolecular duplex.

The silver-nucleoside complex [Ag(i)-(3-cytidine)], , self-assembles to form a supramolecular metal-mediated base-pair array highly analogous to those seen in metallo-DNA. A combination of complementary hydrogen-bonding, hydrophobic and argentophilic interactions drive the formation of a double-helix with a continuous silver core. Electrical measurements on show that despite having Ag···Ag distances within <5% of the metallic radii, the material is electrically insulating.

Marine antifouling performance of polymer coatings incorporating zwitterions.

Zwitterionic materials display antifouling promise, but their potential in marine anti-biofouling is still largely unexplored. This study evaluates the effectiveness of incorporating small quantities (0-20% on a molar basis) of zwitterions as sulfobetaine methacrylate (SBMA) or carboxybetaine methacrylate (CBMA) into lauryl methacrylate-based coatings whose relatively hydrophobic nature encourages adhesion of the diatom Navicula incerta, a common microfouling organism responsible for the formation of 'slime'. This approach allows potential enhancements in antifouling afforded by zwitterion incorporation to be easily quantified.

A coordination polymer for the site-specific integration of semiconducting sequences into DNA-based materials.

Advances in bottom-up material design have been significantly progressed through DNA-based approaches. However, the routine integration of semiconducting properties, particularly long-range electrical conduction, into the basic topological motif of DNA remains challenging. Here, we demonstrate this with a coordination polymer derived from 6-thioguanosine (6-TG-H), a sulfur-containing analog of a natural nucleoside.

From Monochrome to Technicolor: Simple Generic Approaches to Multicomponent Protein Nanopatterning Using Siloxanes with Photoremovable Protein-Resistant Protecting Groups.

We show that sequential protein deposition is possible by photodeprotection of films formed from a tetraethylene-glycol functionalized nitrophenylethoxycarbonyl-protected aminopropyltriethoxysilane (NPEOC-APTES). Exposure to near-UV irradiation removes the protein-resistant protecting group, and allows protein adsorption onto the resulting aminated surface. The protein resistance was tested using proteins with fluorescent labels and microspectroscopy of two-component structures formed by micro- and nanopatterning and deposition of yellow and green fluorescent proteins (YFP/GFP).

Two-Dimensional Frameworks Based on Ag(I)-N Bond Formation: Single Crystal to Single Molecular Sheet Transformation.

A series of new two-dimensional coordination framework materials, based on Ag(I)-N bond formation, has been synthesized and structurally characterized by single crystal methods. Reactions between the poly-monodentate bridging ligand N,N'-((1r,4r)-cyclohexane-1,4-diyl)bis(1-(pyridin-3-yl)methanimine), L1, and silver salts yield compounds {[Ag(L1)(MeCN)](CFSO)}, 1, {[Ag(L1)(PFO)]·HO}, 2, and {Ag(L1)(tosylate)}, 3. The frameworks of these materials exhibit two distinct net topologies: 3.

Interference lithographic nanopatterning of plant and bacterial light-harvesting complexes on gold substrates.

We describe a facile approach for nanopatterning of photosynthetic light-harvesting complexes over macroscopic areas, and use optical spectroscopy to demonstrate retention of native properties by both site-specifically and non-specifically attached photosynthetic membrane proteins. A Lloyd's mirror dual-beam interferometer was used to expose self-assembled monolayers of amine-terminated alkylthiolates on gold to laser irradiation. Following exposure, photo-oxidized adsorbates were replaced by oligo(ethylene glycol) terminated thiols, and the remaining intact amine-functionalized regions were used for attachment of the major light-harvesting chlorophyll-protein complex from plants, LHCII.

Versatile thiol-based reactions for micrometer- and nanometer-scale photopatterning of polymers and biomolecules.

Thiol-based chemistry provides a mild and versatile tool for surface functionalization. In the present work, mercaptosilane films were patterned by utilizing UV-induced photo-oxidation of the thiol to yield sulfonate groups via contact and interferometric lithography (IL). These photo-generated sulfonic acid groups were used for selective immobilization of amino-functionalized molecules after activation with triphenylphosphine ditriflate (TPPDF).

Fabrication of Self-Cleaning, Reusable Titania Templates for Nanometer and Micrometer Scale Protein Patterning.

The photocatalytic self-cleaning characteristics of titania facilitate the fabrication of reuseable templates for protein nanopatterning. Titania nanostructures were fabricated over square centimeter areas by interferometric lithography (IL) and nanoimprint lithography (NIL). With the use of a Lloyd's mirror two-beam interferometer, self-assembled monolayers of alkylphosphonates adsorbed on the native oxide of a Ti film were patterned by photocatalytic nanolithography.

Fast, simple, combinatorial routes to the fabrication of reusable, plasmonically active gold nanostructures by interferometric lithography of self-assembled monolayers.

We describe a fast, simple method for the fabrication of reusable, robust gold nanostructures over macroscopic (cm(2)) areas. A wide range of nanostructure morphologies is accessible in a combinatorial fashion. Self-assembled monolayers of alkylthiolates on chromium-primed polycrystalline gold films are patterned using a Lloyd's mirror interferometer and etched using mercaptoethylamine in ethanol in a rapid process that does not require access to clean-room facilities.

Zwitterionic poly(amino acid methacrylate) brushes.

A new cysteine-based methacrylic monomer (CysMA) was conveniently synthesized via selective thia-Michael addition of a commercially available methacrylate-acrylate precursor in aqueous solution without recourse to protecting group chemistry. Poly(cysteine methacrylate) (PCysMA) brushes were grown from the surface of silicon wafers by atom-transfer radical polymerization. Brush thicknesses of ca.

Fabrication of molecular nanopatterns at aluminium oxide surfaces by nanoshaving of self-assembled monolayers of alkylphosphonates.

Nanoshaving, by tracing an atomic force microscope probe across a surface at elevated load, has been used to fabricate nanostructures in self-assembled monolayers of alkylphosphonates adsorbed at aluminium oxide surfaces. The simple process is implemented under ambient conditions. Because of the strong bond between the alkylphosphonates and the oxide surface, loads in excess of 400 nN are required to pattern the monolayer.

Generic methods for micrometer- and nanometer-scale surface derivatization based on photochemical coupling of primary amines to monolayers of aryl azides on gold and aluminum oxide surfaces.

A series of aryl azide terminated thiols and phosphonic acids has been synthesized, and used to prepare self-assembled monolayers on (respectively) gold and aluminum oxide surfaces. The rates of photoactivation were determined using contact angle measurement and X-ray photoelectron spectroscopy (XPS). The behavior of a diazirine functionalized aryl thiol was also studied.

Spectroscopic and atomic force microscopy characterization of the electrografting of 3,5-bis(4-diazophenoxy)benzoic acid on gold surfaces.

The synthesis of a bipodal diazonium salt, 3,5-bis(4-diazophenoxy)benzoic acid, and the study of its electrochemical deposition on gold surfaces is presented. The presence of the organic layer on the gold surface was characterized using atomic force microscopy and X-ray photoelectron spectroscopy, demonstrating the presence of phenyl groups, indicative of the grafted layer as well as the formation of multilayers, dependent on the electrografting conditions.

Micrometer and nanometer scale photopatterning of proteins on glass surfaces by photo-degradation of films formed from oligo(ethylene glycol) terminated silanes.

Exposure of films formed by the adsorption of oligo(ethylene glycol) (OEG) functionalized trichlorosilanes on glass to UV light from a frequency-doubled argon ion laser (244 nm) causes photodegradation of the OEG chain. Although the rate of degradation is substantially slower than for monolayers of OEG terminated thiolates on gold, it is nevertheless possible to form micrometer-scale patterns by elective adsorption of streptavidin to exposed regions. A low density of aldehyde functional groups is produced, and this enables derivatization with nitrilotriacetic acid via an amine linker.

Large area nanopatterning of alkylphosphonate self-assembled monolayers on titanium oxide surfaces by interferometric lithography.

We demonstrate that interferometric lithography offers a fast, simple route to nanostructured self-assembled monolayers of alkylphosphonates on the native oxide of titanium. Exposure at 244 nm using a Lloyd's mirror interferometer caused the spatially periodic photocatalytic degradation of the adsorbates, yielding nanopatterns that extended over square centimetre areas. Exposed regions were re-functionalised by a second, contrasting alkylphosphonate, and the resulting patterns were used as templates for the assembly of molecular nanostructures; we demonstrate the fabrication of lines of polymer nanoparticles 46 nm wide.