Stretchable light-emitting electrochemical cells using an elastomeric emissive material.

Dispersing an ionic transition metal complex into an elastomeric matrix enables the fabrication of intrinsically stretchable light-emitting devices that possess large emission areas (∼175 mm(2)) and tolerate linear strains up to 27% and repetitive cycles of 15% strain. This work demonstrates the suitability of this approach to new applications in conformable lighting that require uniform, diffuse light emission over large areas.

Templated self-assembly of glass microspheres into ordered two-dimensional arrays under dry conditions.

This paper describes a new approach to mesoscale self-assembly in which a stream of nitrogen is used to propel micrometer-scale components toward a template of patterned liquid adhesive drops. This approach combines the use of capillary forces to hold the components in place with dry processing conditions. Eliminating the use of a liquid medium to suspend components is an important goal for mesoscale self-assembly methods because it eliminates the need for special encapsulation to protect electrically functional components. We demonstrate the dry self-assembly approach by assembling 100 microm glass microspheres into a variety of 2D patterns. A study of defects in these arrays relates parameters associated with the template--density of binding sites and volume of liquid adhesive comprising the drops--to the frequency of defects arising from the incorporation of additional microspheres into the array. Optimized template parameters and self-assembly conditions yield 2D arrays with defect rates of approximately 4-5%. We also demonstrate the versatility of this self-assembly method by producing ordered binary arrays of clear and black glass microspheres.

Selectively metallized polymeric substrates by microcontact printing an aluminum(III) porphyrin complex.

We report a simple, low-cost method for the fabrication of copper wires and contacts on a wide range of flexible, rigid, and inert polymeric substrates. This method relies on procedures to oxidize the polymeric substrates to form surface-bound carboxylic acid groups. Patterning of an aluminum porphyrin ink using microcontact printing results in the formation of an aluminum porphyrin monolayer that is covalently anchored to the oxidized polymer surface via an aluminum-carboxylate bond. We characterize this monolayer using ultraviolet-visible absorption spectra, reflection-absorption infrared spectroscopy, and contact angle measurements. Patterned aluminum porphyrin monolayers bind a Pd/Sn colloidal catalyst from solution that subsequently initiates the selective deposition of copper in an electroless plating solution. We demonstrate the fabrication of patterned copper films on a variety of both flexible and rigid polymers with minimum feature sizes of 2 microm over 2 cm(2) substrates. Measurements of electrical resistivity of copper wires fabricated on flexible poly(ethylene naphthalate) (PEN) substrates as a function of the bending radius show no negative impact on electrical performance at bending radii as small as 500 microm. Permanently damaging the PEN substrate by creasing (corresponding to a bending radius of 100 microm) results in only a modest increase in resistivity.

Coordination polymers based on aluminum(III) porphyrins.

Aluminum(III) porphyrin carboxylate complexes have shown an affinity for a sixth nitrogenous ligand. The use of isonicotinic or nicotinic acid, which offers both a carboxylate and a nitrogen donor in the same molecule, resulted in the formation of one-dimensional (1-D) coordination polymers. The complexes and their linear oligomers have been characterized by (1)H NMR spectroscopy and nanoelectrospray ionization spectrometry. X-ray analyses confirmed the formation of the 1-D polymers in the solid state.

Controlling the ON/OFF threading of a terpyridine containing [2]pseudorotaxane ligand via changes in coordination geometry.

A 1,2-bis(pyridinium)ethane type axle containing a terpyridine chelate group, when combined with 24-membered crown ethers, forms [2]pseudorotaxanes, the stability of which can be controlled by coordination of metal ions with different geometries.

Aluminium(III) porphyrins as supramolecular building blocks.

Aluminium(III) porphyrin-carboxylate complexes, including a porphyrin pentamer, have been characterised by NMR spectroscopy, MALDI spectrometry and single crystal X-ray diffraction; these complexes can also be coordinated by a sixth, nitrogenous, ligand to the aluminium(III) centre.

Wire-type ruthenium(II) complexes with terpyridine-containing [2]rotaxanes as ligands: Synthesis, characterization, and photophysical properties.

[2]Rotaxanes based on the 1,2-bis(pyridinium)ethane subset[24]crown-8 ether motif were prepared that contain a terminal terpyridine group for coordination to a transition-metal ion. These rotaxane ligands were utilized in the preparation of a series of heteroleptic [Ru(terpy)(terpy-rotaxane)]2+ complexes. The compounds were characterized by 1D and 2D 1H NMR spectroscopy, X-ray crystallography, and high-resolution electrospray ionization mass spectrometry. The effect of using a rotaxane as a ligand was probed by UV/Vis/NIR absorption and emission spectroscopy of the Ru(II) complexes. In contrast with the parent [Ru(terpy)(2)]2+ complex, at room temperature the examined complexes exhibit a luminescence band in the near infrared region and a relatively long lived triplet metal-to-ligand charge-transfer (3MLCT) excited state, owing to the presence of strong-electron-acceptor pyridinium substituents on one of the two terpy ligands. Visible-light excitation of the Ru-based chromophore in acetonitrile at room temperature causes an electron transfer to the covalently linked 4,4'-bipyridinium unit and the quenching of the MLCT luminescence. The 3MLCT excited state, however, is not quenched at all in rigid matrix at 77 K. The rotaxane structure was found to affect the absorption and luminescence properties of the complexes. In particular, when a crown ether surrounds the cationic axle, the photoinduced electron-transfer process is slowed down by a factor from 2 to 3. Such features, together with the synthetic and structural advantages offered by [Ru(terpy)2]2+-type complexes compared to, for example, [Ru(bpy)3]2+-type compounds, render these rotaxane-metal complexes promising candidates for the construction of photochemical molecular devices with a wire-type structure.

Host-guest interactions template: the synthesis of a [3]catenane.

Formation of a [3]catenane containing dibenzo-24-crown ether wheels and a large dipyridiniumethane ring is templated by formation of a host-guest adduct between the [3]catenane and the external crown ether.

Pseudo-polyrotaxanes based on a protonated version of the 1,2-bis(4,4'-bipyridinium)ethane-24-crown-8 ether motif.

Protonated 1,2-bis(4,4'-bipyridinium)ethane axles and dibenzo-24-crown-8 ether wheels thread to form [2]pseudorotaxanes which associate in the solid state to form pseudopolyrotaxanes by hydrogen bonding or pi-stacking.