Abstract This paper describes the rheological behavior of liquid metal eutectic gallium‐indium (EGaIn) as it is injected into microfluidic channels to form stable microstructures metal. EGaIn well‐ ;suited for this application because its properties at room temperature: behaves like an elastic material until experiences a critical surface stress, which point yields and flows readily. These allow fill microchannels rapidly when sufficient pressure applied inlet channels, yet maintain...

A great GaIn: Micrometer-sized conformal electrodes formed from the title compound are shown to be ideal for measuring electrical properties of self-assembled monolayers. The image shows bifurcation EGaIn between a metal needle and an Ag surface (not shown) at point indicated by two white arrows. portion above arrows will form electrode. Supporting information this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z703642_s.pdf or author. Please note: publisher...

Molecules designed to carry out photochemical energy conversion typically employ several sequential electron transfers, as do photosynthetic proteins. Yet, these molecules not achieve the extensive charge transport characteristic of semiconductor devices. We have prepared a large molecule in which four perylene-3,4:9,10-tetracarboxydiimide (PDI) that both collect photons and accept electrons are attached central zinc 5,10,15,20-tetraphenylporphyrin (ZnTPP) donor. This self-assembles into...

Functional molecular wires are essential for the development of electronics. Charge transport through molecules occurs primarily by means two mechanisms, coherent superexchange and incoherent charge hopping. Rates in which dominates decrease approximately exponentially with distance, precludes using these as effective wires. In contrast, rates hopping prevails should display nearly distance independent, wirelike behavior. We now able to determine how each mechanism contributes overall...

This Perspective reviews strategies for tuning the surface chemistry of colloidal semiconductor nanocrystals (quantum dots, QDs) to function as photoredox catalysts or sensitizers redox organic transformations. These include (i) charge density encourage high-affinity interactions between QD and substrate (or co-catalyst) in absence a covalent linkage, (ii) maximizing QD's catalytic area through ligand exchange, (iii) using "hole shuttle" ligands efficiently extract oxidative equivalents from...

This paper describes the use of cadmium sulfide quantum dots (CdS QDs) as visible-light photocatalysts for reduction nitrobenzene to aniline through six sequential photoinduced, proton-coupled electron transfers. At pH 3.6-4.3, internal yield photons-to-reducing electrons is 37.1% over 54 h illumination, with no apparent decrease in catalyst activity. Monitoring QD exciton by transient absorption reveals that, each step catalytic cycle, sacrificial reductant, 3-mercaptopropionic acid,...

Climate change and global energy demands motivate the search for sustainable transformations of carbon dioxide (CO2) to storable liquid fuels. Photocatalysis is a pathway direct conversion CO2 CO, one step within light-powered reaction networks that could, if efficient enough, transform solar landscape. To date, best performing photocatalytic reduction systems operate in nonaqueous solvents, but technologically viable fuels will likely water. Here we demonstrate catalytic photoreduction CO...

The synthesis as well the structural and photophysical characterization of two isoleptic bis-cyclometalated Pt(II) Pd(II) complexes, namely [PtL] [PdL], bearing a tailored dianionic tetradentate ligand (L2–) are reported. isostructural character intermolecular interactions [PdL] were assessed by NMR spectroscopy X-ray diffraction analysis. Both complexes show fully ligand-controlled aggregation, demonstrating that judicious molecular design can tune properties. In fact, introduction fluorine...

This paper compares the structural and electrical characteristics of self-assembled monolayers (SAMs) n-alkanethiolates, SCn (n = 10, 12, 14), on two types silver substrates: one used as-deposited (AS-DEP) by an electron-beam evaporator, prepared using method template-stripping. Atomic force microscopy showed that template-stripped (TS) surfaces were smoother had larger grains than AS-DEP surfaces, reflectance−absorbance infrared spectroscopy SAMs formed TS substrates more crystalline...

This paper describes a quantitative analysis of the chemical composition organic/inorganic interfaces colloidal 3.1-nm CdSe quantum dots (QDs) synthesized with trioctylphosphine oxide (TOPO) as coordinating solvent and purified by successive precipitations from chloroform/methanol solvent/nonsolvent system. A combination X-ray photoelectron spectroscopy, inductively coupled plasma-atomic emission NMR (both 1H 31P) reveals that only ligands form stable population on surface QDs are X-type...

This paper describes the use of several methods template stripping (TS) to produce ultraflat films silver, gold, palladium, and platinum on both rigid polymeric mechanical supports: a composite glass ultraviolet (UV)-curable adhesive (optical adhesive, OA), solder, poly(dimethyl siloxane) (PDMS) OA, bare OA. Silicon supporting its native oxide layer (Si/SiO2) serves as for (mTS), in which metal film is mechanically cleaved from template, chemical (cTS), film−template immersed solution...

A combination of transient absorption (TA) and time-resolved photoluminescence (TRPL) spectroscopies performed on solution-phase samples colloidal CdSe quantum dots (QDs) allows the construction a time-resolved, charge carrier-resolved map decay from first excitonic state QD. Data TA TRPL yield same six exponential components, with time constants ranging ∼1 ps to 50 ns, for decay. Comparison signals in visible near-infrared (NIR) spectral regions enables determination relative contributions...

Transient absorption (TA) spectroscopy of solution-phase mixtures colloidal CdS quantum dots (QDs) with acid-derivatized viologen molecules, N-[1-heptyl],N'-[3-carboxypropyl]-4,4'-bipyridinium dihexafluorophosphate (V(2+)), indicates electron transfer occurs from the conduction band QD to LUMO V(2+) after photoexcitation a band-edge exciton in QD. Analysis magnitude ground state bleach as function molar ratio QD:V(2+) yields QD-ligand adsorption constant, K(a) (4.4 × 10(4) M(-1)) for ligands...

Coordination of phenyldithiocarbamate (PTC) ligands to solution-phase colloidal CdSe quantum dots (QDs) decreases the optical band gap, E(g), QDs by up 220 meV. These values DeltaE(g) are largest shifts achieved chemical modification surfaces and are-by more than an order magnitude in energy-the bathochromic for either solution or solid phases. Measured upon coordination PTC correspond apparent increase excitonic radius 0.26 +/- 0.03 nm; this delocalization is independent size QD radii, R =...

This review outlines the set of technical approaches to answering three major questions about surface chemistry colloidal semiconductor quantum dots (QDs): (i) What is chemical structure ligands on QD? (ii) How many each type ligand are (iii) intermolecular (geometry) Each section addresses accessability relevant techniques—which include 1D and 2D NMR, vibrational electronic absorption transient spectroscopies, various elemental analyses—and their sensitivity applicability specified...

We observe well-defined regions of superexchange and thermally activated hopping in the temperature dependence charge recombination (CR) a series donor-bridge-acceptor (D-B-A) systems, where D = phenothiazine (PTZ), B p-phenylene (Ph(n)), n 1-4, A perylene-3,4:9,10-bis(dicarboximide) (PDI). fit to CR rates 3 4 compounds yields activation barriers 1290 2030 cm(-1), respectively, which match closely with theoretically predicted experimentally observed for planarization terphenyl quaterphenyl....

The study of photoinitiated electron transfer in donor–bridge–acceptor molecules has helped elucidate the distance dependence rates and behavior various mechanisms. In all reported cases, energies bridge electronic states involved change dramatically as length is varied. We report here, contrast, an instance which bridge, therefore over transferred, can be varied without significantly changing relevant states. A series having phenothiazine (PTZ) donors, 2,7-oligofluorene (FL n ) bridges,...

Photosensitization of molecular catalysts to reduce CO2 CO is a sustainable route storable solar fuels. Crucial the sensitization process highly efficient transfer redox equivalents from sensitizer catalyst; in systems with sensitizers, this often slow because it gated by diffusion-limited collisions between and catalyst. This article describes photosensitization meso-tetraphenylporphyrin iron(III) chloride (FeTPP) catalyst colloidal, heavy metal-free CuInS2/ZnS quantum dots (QDs) using 450...

This paper describes the use of electrostatic assemblies negatively charged colloidal CuInS2/ZnS quantum dot (QD) sensitizers and positively charged, trimethylamino-functionalized iron tetraphenylporphyrin catalysts (FeTMA) to photoreduce CO2 CO in water upon illumination with 450 nm light. system achieves a turnover number (TON) (per FeTMA) after 30 h illumination, selectivity 99%. Its sensitization efficiency (TON per Joule photons absorbed) is factor 11 larger than previous record for...