using a solenoid coil with an iron core of 2.5 cm diameter. The core was positioned a couple of millimeters away from the substrate in order to provide a substantially uniform magnetic field over the extent of the substrate. This uniform magnetic field was sufficient to bias the magnetic moments of the beads in the direction perpendicular to the substrate. However, the same field had little effect on the magnetization of the micromagnets because of their very high shape anisotropy (extremely large magnetic energy would be required to turn the micromagnets' magnetization out of the plane). We report the facile microstructuring of conjugated polymers 1±5 (see Scheme 1) into hexagonally ordered twodimensional (2D) arrays by evaporative cooling with the subsequent condensation of water droplets onto a dilute solution of polymer in carbon disulfide. This report is the first example in which rigid rod-like polymers are microstructured into inverse hexagonal arrays by the formation, and subsequent crystallization of ªbreath figuresº. [1,2] Micro-and nanostructuring of organic semiconductors is of critical importance in the fabrication of photonic bandgap materials and heterojunction devices, such as photovoltaic cells and thin-film transistors.[3±5] A variety of templating methods based on self-assembly have been developed to create structures with micrometer and submicrometer dimensions. These include templating using ordered arrays of colloidal particles, [6±10] templating using an emulsion, [11] honeycomb structures formed by polymers with rod±coil architecture, [4,12±14]

The optical properties of thin films of poly[p-(2,5-didodecylphenylene)ethynylene] (DPPE) have been investigated. In chloroform solution the DPPE exhibit structured blue emission with a lifetime of 0.4 ns. In contrast to the solution, pristine DPPE films show a broad featureless green fluorescence with a nonexponential decay with time constants of 1.15 ns (8%) and 5.9 ns (92%). Upon annealing, the emission spectrum returns to a structured blue emission similar to the solution, and the fluorescence decay is nonexponential with a component at 0.45 ns (38%) and 90 ps (62%). Both spin-cast and annealed films possess similar absorption spectra, suggesting that the lifetime difference is due to an excimer-like state in the pristine film and efficient fluorescence from isolated chains within the annealed films. The decrease of the fluorescence lifetime from 0.4 ns (DPPE in solution) to 90 ps (annealed DPPE films) is further attributed to the lack of conformational disorder found within the ordered solid state.

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The reaction of [(C5H5)(CO)Fe]2^-CO)^-CH)+PF6•, 1, with ethylene produced [(C5H5)(CO)Fe]2Oi-CO)Ot-CCH2CH3)+PF6", 4, in 68% yield. 4 reacted with trimethylamine to give [(C5H5)(CO)Fe]2(^-CO)(M-C=CHCH3), 5, in 84% yield. 1 reacted regioselectively with propene, 1-butene, 1-pentene, ieri-butylethylene, styrene, butadiene, allylbenzene, and isobutylene to give similar µ-alkylidyne products in 76-85% yields. The syn addition of hydrocarbation was established by the reaction of 1 with (£)-and (Z)-1,2-dideuterio-3,3-dimethyl-1 -butene, 23-E and 23-Z. The rate of the reaction of 1 with fra«s-2-butene at -50 °C followed second-order kinetics with k2 = 9.2 ± 0.7 X 10'1 23 M'1 s'1. Competition techniques were used to measure the relative reactivity of 1 toward alkenes at -50 °C, and electron-donating alkyl substituents substantially increased the reactivity of the alkene. The deuterium kinetic isotope effect for the reaction of 1 with propene and isobutylene at -50 °C was found to be 0.74 ± 0.03 and 0.80 ± 0.03. The regiochemistry, relative rates, and kinetic isotope effects are consistent with a transition state for the rate-determining step of hydrocarbation which involves only initiation of a bond from (21) Casey, C.