Development of Fluoride-Ion Primary Batteries: The Electrochemical Defluorination of CF .

The lithium-carbon monofluoride (Li-CF ) couple has the highest specific energy of any practical battery chemistry. However, the large polarization associated with the CF electrode (>1.5 V loss) limits it from achieving its full discharge energy, motivating the search for new CF reaction mechanisms with reduced overpotential.

An Efficient Synthesis of Geminal-Dialkyl Dienes for Olefin Metathesis Polymerization.

A robust synthesis of -dialkyl acyclic diene monomers has been developed. This route is scalable, flexible, and biorenewable, allowing for the production of a wide range of diene monomers of different lengths and different -dialkyl substitution starting from unsaturated esters derived from seed oils. The metathesis polymerization of these monomers and the hydrogenation of the resulting polyolefins leads to telechelic -dialkyl polyethylenes, which can be used as elastomers in the synthesis of polyurethanes and other block polymers.

Re(tBu-bpy)(CO)Cl Supported on Multi-Walled Carbon Nanotubes Selectively Reduces CO in Water.

The selective electrochemical reduction of CO to CO in water by a Re(tBu-bpy)(CO)Cl catalyst incorporated into multi-walled carbon nanotubes (MWCNT) was investigated. Current densities of ∼4 mA/cm and selectivities (FE) of 99% were achieved at -0.56 V vs RHE in CO-saturated aqueous KHCO solutions.

Room-temperature cycling of metal fluoride electrodes: Liquid electrolytes for high-energy fluoride ion cells.

Fluoride ion batteries are potential "next-generation" electrochemical storage devices that offer high energy density. At present, such batteries are limited to operation at high temperatures because suitable fluoride ion-conducting electrolytes are known only in the solid state. We report a liquid fluoride ion-conducting electrolyte with high ionic conductivity, wide operating voltage, and robust chemical stability based on dry tetraalkylammonium fluoride salts in ether solvents.

In Situ Polysulfide Detection in Lithium Sulfur Cells.

Lithium sulfur batteries promise significant improvements in specific energy compared to Li-ion, but are limited by capacity fade upon cycling. Efforts to improve durability have focused on suppressing the solubility of intermediate polysulfides in the electrolyte. Here we describe an in situ electrochemical polysulfide detection method based on the cyclic volatmmetric response.

Manipulating the ABCs of self-assembly via low-χ block polymer design.

Block polymer self-assembly typically translates molecular chain connectivity into mesoscale structure by exploiting incompatible blocks with large interaction parameters (χ). In this article, we demonstrate that the converse approach, encoding low-χ interactions in ABC bottlebrush triblock terpolymers (χ [Formula: see text] 0), promotes organization into a unique mixed-domain lamellar morphology, which we designate LAM Transmission electron microscopy indicates that LAM exhibits ACBC domain connectivity, in contrast to conventional three-domain lamellae (LAM) with ABCB periods. Complementary small-angle X-ray scattering experiments reveal a strongly decreasing domain spacing with increasing total molar mass.

Megasupramolecules for safer, cleaner fuel by end association of long telechelic polymers.

We used statistical mechanics to design polymers that defy conventional wisdom by self-assembling into "megasupramolecules" (≥5000 kg/mol) at low concentration (≤0.3 weight percent). Theoretical treatment of the distribution of individual subunits—end-functional polymers—among cyclic and linear supramolecules (ring-chain equilibrium) predicts that megasupramolecules can form at low total polymer concentration if, and only if, the backbones are long (>400 kg/mol) and end-association strength is optimal.

Homo- and heterometallic luminescent 2-D stilbene metal-organic frameworks.

Metal-organic frameworks (MOFs) can provide a matrix for the assembly of organic chromophores into well-defined geometries, allowing for tuning of the material properties and study of structure-property relationships. Here, we report on the effect of the coordinated metal ion on the luminescence properties of eight isostructural MOFs having the formula M(1)2M(2)L3(DMF)2 (M(1) = M(2) = Zn (1), Cd (2), Mn (3), Co (4); M(1) = Zn, M(2) = Cd (5), Mn (6), Co (7); M(1) = Co, M(2) = Mn (8); L = trans-4,4'-stilbene dicarboxylate), synthesized by reaction of the appropriate metal nitrate or mixtures of metal nitrates with LH2 in DMF. The crystal structures of 2, 3 and 5-8 were determined by X-ray diffraction to be composed of trinuclear metal clusters linked by stilbene dicarboxylate linkers in a paddlewheel geometry, extending to form a 2-D layered structure.

The modification of indium tin oxide with phosphonic acids: mechanism of binding, tuning of surface properties, and potential for use in organic electronic applications.

Transparent metal oxides, in particular, indium tin oxide (ITO), are critical transparent contact materials for applications in next-generation organic electronics, including organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs). Understanding and controlling the surface properties of ITO allows for the molecular engineering of the ITO-organic interface, resulting in fine control of the interfacial chemistries and electronics. In particular, both surface energy matching and work function compatibility at material interfaces can result in marked improvement in OLED and OPV performance.

Diastereoselective heterogeneous bromination of stilbene in a porous metal-organic framework.

Postsynthetic modification of a porous MOF, Zn(4)O(trans-4,4'-stilbene dicarboxylate)(3), with Br(2) results in diastereoselective bromination of the stilbene units. This is a heterogeneous process, with the stereocontrol originating in the rigidity of the coordinated ligand and the porous nature of the MOF, which allows "solution-like" access to reactive sites. X-ray diffraction and N(2) sorption studies suggest that partial bromination serves to increase the stability of this interpenetrated MOF structure.

Intramolecular electron-transfer rates in mixed-valence triarylamines: measurement by variable-temperature ESR spectroscopy and comparison with optical data.

The electron spin resonance spectra of the radical cations of 4,4'-bis[di(4-methoxyphenyl)amino]tolane, E-4,4'-bis[di(4-methoxyphenyl)amino]stilbene, and E,E-1,4-bis{4-[di(4-methoxyphenyl)amino]styryl}benzene in dichloromethane exhibit five lines over a wide temperature range due to equivalent coupling to two 14N nuclei, indicating either delocalization between both nitrogen atoms or rapid intramolecular electron transfer on the electron spin resonance time scale. In contrast, those of the radical cations of 1,4-bis{4-[di(4-methoxyphenyl)amino]phenylethynyl}benzene and E,E-1,4-bis{4-[di(4-n-butoxyphenyl)amino]styryl}-2,5-dicyanobenzene exhibit line shapes that vary strongly with temperature, displaying five lines at room temperature and only three lines at ca. 190 K, indicative of slow electron transfer on the electron spin resonance time scale at low temperatures.

High-speed, sub-15 nm feature size thermochemical nanolithography.

We report a nanolithography technique that allows simultaneous direct control of the local chemistry and topography of thin polymer films. Specifically, a heated atomic force microscope (AFM) tip can write sub-15 nm hydrophilic features onto a hydrophobic polymer at the rate of 1.4 mm per s.

Intervalence transitions in the mixed-valence monocations of bis(triarylamines) linked with vinylene and phenylene-vinylene bridges.

(E)-4,4'-Bis[bis(4-methoxyphenyl)amino]stilbene, 1, (E,E)-1,4-bis[4-[bis(4-methoxyphenyl)amino]styryl]benzene, 2, and two longer homologues, (E,E,E)-4,4'-bis[4-[bis(4-methoxyphenyl)amino]styryl]stilbene, 3, and (E,E,E,E)-1,4-bis(4-[4-[bis(4-methoxyphenyl)amino]styryl]styryl)benzene, 4, have been oxidized to their mono- and dications using tris(4-bromophenyl)aminium hexachloroantimonate. The intervalence charge-transfer (IVCT) band of 1(+) is narrow and asymmetric and exhibits only weak solvatochromism. Analysis of this band indicates that 1(+) is a class-III or class-II/III borderline mixed-valence species.

High charge-carrier mobility in an amorphous hexaazatrinaphthylene derivative.

An isomeric mixture of a tris(pentafluorobenzyl ester) derivative of hexaazatrinaphthylene forms stable amorphous films with an effective charge-carrier mobility of 0.02 cm2/Vs, while the pure 2,8,15-isomer exhibits widely differing morphologies and carrier mobilities (0.001-0.

A fluorine-substituted hexakisdecyloxy- hexa-peri-hexabenzocoronene.

[structure: see text] The first fluorine-substituted hexabenzocoronene has been synthesized and is much more readily reduced than its nonfluorinated analogues. Thin films of this material show columnar order at room temperature, and the charge-carrier mobility measured by the pulse-radiolysis time-resolved microwave conductivity technique is comparable to that of other hexabenzocoronene materials.

Electronic coupling in mixed-valence dinuclear ferrocenes and cobaltocenes with saturated bridging groups.

We have synthesised a series of new dinuclear metallocenes [{M(Cp*)(C5H4)}2X] (Cp* = eta5-pentamethylcyclopentadienyl; M = Fe, Co, X = CMe2, SiMe2, GeMe2; M = Fe, X = Si2Me4). For the neutral dicobalt complexes, magnetic susceptibility measurements reveal intramolecular antiferromagnetic interactions of -21 and -14 cm(-1) for SiMe2- and GeMe2-bridged species, respectively, but negligible interaction for the CMe2-bridged compound. In contrast, intervalence charge-transfer (IVCT) data for the mixed-valence monocations of both Fe and Co complexes show electronic coupling to decrease in the order CMe2 > SiMe2 > GeMe2.

A mixed-valence bis(diarylamino)stilbene: crystal structure and comparison of electronic coupling with biphenyl and tolane analogues.

The E-4,4'-bis[di(p-anisyl)amino]stilbene cation is a class-III mixed-valence species with electronic coupling comparable to that in its biphenyl-bridged analogue, whereas its tolane-bridged analogue belongs to class II.

Delocalization in platinum-alkynyl systems: a metal-bridged organic mixed-valence compound.

A complex featuring two triarylamine redox centers bridged by Pt, trans-bis(triethylphosphine)-bis{4-[bis(4-methoxyphenyl)amino]phenylethynyl} platinum(II), has been synthesized as a model system for pi-conjugated Pt-containing polymers. Analysis of the intervalence charge-transfer band displayed by its mixed-valence monocation affords a quantitative assessment of electronic delocalization through the Pt bridge; this is found to be only slightly smaller than that determined for a benzene-bridged analogue. These results are supported by density functional theory calculations, which show that the active orbitals involved in the electron-transfer process in both cases have similar delocalization through the bridging unit.

A novel coordination mode for pentalene in trinuclear chromium complexes.

The first chromium pentalene complexes have been characterized; in these the ligand displays a hitherto-unknown bonding mode whereby a dimeric [Cr(Cp*)](2)(mu-OR) unit is bound (mu:eta(2):eta(2))- to one face, and Cp*Cr is bound eta(5)- to the other. The magnetic properties of these compounds can be understood as the superposition of those of a chromocene and an antiferromagnetically coupled Cr[bond]Cr bonded unit.

[V(eta5-C5H5)]2C8H6: a bimetallic pentalene-bridged complex with multiple bonding between the metal atoms.

The bimetallic complex [V(Cp)]2Pn, containing a V-V triple bond, has been synthesised; the vanadium centres adopt a syn-coordination and the complex exhibits a high-spin/low-spin equilibrium in both solution and the solid-state.

Pentalene complexes of group 7 metal carbonyls: an organometallic mixed-valence system with very large metal-metal electronic coupling.

The bimetallic complexes [M(CO)(3)](2)(mu:eta(5):eta(5)-Pn) (Pn = pentalene, C(8)H(6); M = Mn, Re) have been synthesized and characterized crystallographically; the Mn compound was isolated as solely the anti-isomer, while the Re analogue was formed as a mixture of anti- and syn-isomers. [Mn(CO)(3)](2)(mu:eta(5):eta(5)-Pn) may be reduced chemically to its mono- and dianions; the mixed-valence Mn(I)/Mn(0) monoanion is shown by ESR, vibrational, and electronic spectroscopies to be a Robin-Day class III system with an exceptionally large electronic coupling between the metal centers.