Raman spectroscopic monitoring of droplet polymerization in a microfluidic device.

Microfluidic methodologies are becoming increasingly important for rapid formulation and screening of materials, and development of analytical tools for multiple sample screening is a critical step in achieving a combinatorial 'lab on a chip' approach. This work demonstrates the application of Raman spectroscopy for analysis of monomer composition and degree of conversion of methacrylate-based droplets in a microfluidic device. Droplet formation was conducted by flow focusing on the devices, and a gradient of component composition was created by varying the flow rates of the droplet-phase fluids into the microchannels. Raman data were collected using a fiber optic probe from a stationary array of the droplets/particles on the device, followed by partial least squares (PLS) calibration of the first derivative (1600 cm(-1) to 1550 cm(-1)) allowing successful measurement of monomer composition with a standard error of calibration (SEC) of +/-1.95% by volume. Following photopolymerization, the percentage of double bond conversion of the individual particles was calculated from the depletion of the normalized intensity of the C[double bond, length as m-dash]C stretching vibration at 1605 cm(-1). Raman data allowed accurate measurement of the decrease in double bond conversion as a function of increasing crosslinker concentration. The results from the research demonstrate that Raman spectroscopy is an effective, on-chip analytical tool for screening polymeric materials on the micrometre scale.

Microfluidic platform for the generation of organic-phase microreactors.

Rapid prototyping photolithography of a thiolene-based resin was used to fabricate microfluidic devices stable to aliphatic and aromatic organic solvents. The swelling of the cross-linked polymer matrix in various organic solvents was quantified, and the solvent resistance properties of these microfluidic devices are described. Discrete droplets of hexanes and toluene of uniform size were generated in microfluidic devices inside a water matrix containing SDS surfactant (SDS = sodium dodecyl sulfate). Variation of water and organic flow rates in the fluidic channels was used to control droplet size and separation. Droplet composition could be controlled by varying flow rates of two joined organic streams. Organic-phase synthetic reactions within the droplets were demonstrated with the bromination of alkenes inside benzene droplets.

Insertion of SO2 into a sulfide-bridged M-Ge bond: synthesis, characterization, and reactivity of the O-germyl-S-sulfoxylate.

Addition of SO(2) to [formula: see text](1) results in the insertion of SO(2) into the Pd-Ge bond to give the O-germyl-S-sulfoxylate insertion isomer (Et3P)2Pd(mu-S)S(O)OGe[N(SiMe3)2]2 (2). Heating solutions of 2 results in the formation of (Et3P)Pd(SGe[N(SiMe3)2]2OSOGe[N(SiMe3)2]2S) (3) and a LnPd(0) fragment. X-ray crystal structures of 2 and 3 are reported.

Reactions of palladium germylene complexes: formation of sulfide bridges.

Reactivity of three novel Pd germylene species is presented. (Et(3)P)(2)PdGe[N(SiMe(3))(2)](2) (1) and (dppe)PdGe[N(SiMe(3))(2)](2) (6) react with COS to give the sulfide bridged species (Et3P)2Pd(mu S)Ge[N(SiMe3)2]2 (2) and (dppe)Pd(mu S)Ge-[N(SiMe3)2]2 (7) (dppe = (diphenylphosphino)ethane). (Ph(3)P)(2)PdGe[N(SiMe(3))(2)](2) (4) reacts with COS to give the disulfide bridged complex (Ph(3)P)(2)Pd(muS)(2)Ge[N(SiMe(3))(2)](2) (5) resulting in Pd-Ge bond cleavage. This phosphine dependent reactivity is explored. Crystal structures of 2, 5, 7, and the dimeric form of complex 2, (8), are reported. In the presence of excess germylene, complexes 2 and 5 are shown to partially regenerate their parent palladium germylene complexes, 1 and 4, respectively, via photolysis or heating.

Structures of anhydrous and hydrated copper(II) hexafluoroacetylacetonate.

Crystal structure analyses are reported for anhydrous copper(II) hexafluoroacetylacetonate (Cu(hfac)(2)) and for two of its hydrates. The anhydrous compound (Cu(hfac)(2), 1: P1; at 100 K, a = 5.428(1), b = 5.849(1), c = 11.516(3) A; alpha = 81.47(2), beta = 74.57(2), gamma = 86.96(2) degrees; Z = 1) contains centrosymmetric square-planar complexes with close intermolecular Cu.F contacts. The geometry of the complex is similar to that previously reported for Cu(hfac)(2).toluene. The monoaquo compound (Cu(hfac)(2)(H(2)O), 2: P2(1)/c; at 100 K, a = 10.8300(8), b = 6.5400(6), c = 21.551(3) A; beta = 90.282(8) degrees; Z = 4) consists of square-pyramidal molecules with apical H(2)O ligands, and close-lying F atoms in the sixth coordination sites. The major difference between this structure and the two other polymorphs previously reported is the nature and direction of hydrogen bonds. The yellow-green solid formed from Cu(hfac)(2) with excess H(2)O is identified as the trihydrate. In crystalline form it is the previously unreported [trans-Cu(hfac)(2)(H(2)O)(2)].H(2)O (3: P1; at 150 K, a = 8.3899(3), b = 9.6011(3), c = 11.4852(4) A; alpha = 72.397(2), beta = 79.161(2), gamma = 87.843(2) degrees; Z = 2). There is no conclusive evidence in favor of any solid with the composition Cu(hfac)(2).2H(2)O.