Well-Balanced Ambipolar Charge Transport of Diketopyrrolepyrrole-Based Copolymers: Organic Field-Effect Transistors and High-Voltage Logic Applications

A poly (3,6-bis(thiophen-2-yl)−2,5-bis(2-decyltetradecyl)−2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione-co-(2,3-bis(phenyl)acrylonitrile)) (PDPADPP) copolymer, composed of diketopyrrolopyrrole (DPP) and a cyano (nitrile) group with a vinylene spacer linking two benzene rings, is synthesized via a palladium-catalyzed Suzuki coupling reaction. The electrical performance of PDPADPP in organic field-effect transistors (OFETs) and circuits is investigated. The OFETs based on PDPADPP exhibit typical ambipolar transport characteristics, with the as-cast OFETs demonstrating low field-effect hole and electron mobility values of 0.016 and 0.004 cm² V⁻¹ s⁻¹, respectively. However, after thermal annealing at 240 °C, the OFETs exhibit improved transport characteristics with highly balanced ambipolar transport, showing average hole and electron mobility values of 0.065 and 0.116 cm² V⁻¹ s⁻¹, respectively. To verify the application of the PDPADPP OFETs in high-voltage logic circuits, compact modeling using the industry-standard small-signal Berkeley short-channel IGFET model (BSIM) is performed, and the logic application characteristics are evaluated. The circuit simulation results demonstrate excellent logic application performance of the PDPADPP-based ambipolar transistor and illustrate that the device annealed at 240 °C exhibits ideal circuit characteristics.     

Cysteine adsorption on the Au(111) surface and the electron transfer in configuration of a scanning tunneling microscope: A quantum-chemical approach

Adsorption of two forms, molecule and radical, of amino acid L-cysteine (Cys) on the Au₁₂ cluster that simulates the (111) face of single-crystal gold is studied in the framework of the density functional theory. Effects of solvation of adsorbed Cys particles and lateral interaction in a monolayer are analyzed. The simulation predicts a commensurate adsorption energetics of the molecule and radical, with a difference between the “on-top,” “hollow,” and “bridge” positions. An analysis of lateral electrostatic interactions points to the stability of a cluster comprising six Cys particles, which conforms to the size of a fragment observed experimentally. Adsorption calculations are used to build three-dimensional isosurfaces (STM images), where the tungsten needle of the scanning tunneling microscope is simulated by a tungsten atom or by small clusters. The calculated images are sensitive to both the Cys shape and the orientation of adsorbed Cys particles. Calculation results are compared with fresh in situ submolecular-resolution STM data. Simulated images (with commensurate contributions made by sulfur atom and amino group) built for Cys radical adsorbed in the “on-top” position give best conformance to experiment.     

Cloning, overexpression, purification, and characterization of receptor-interacting protein 3 truncation inEscherichia coli

To facilitate structural studies of receptor-interacting protein 3 (RIP3), we developed a large-scale expression system of a glutathione-S-transferase (GST) fused with an 82 amino acid RIP3 protein inEscherichia coli. RIP3 truncation was subcloned into the pGEX-4T-1 vector and overexpressed in BL21(DE3)RIL cells. The soluble RIP3 protein was successfully purified to homogeneity using GST tag, an anion-exchange column, and gel filtration chromatography. The purity, identity, and conformation of the RIP3 protein were determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blotting, matrix-assisted laser desorption ionization mass spectrometry, circular dichroism, and fluorescence spectroscopic studies. RIP3 showed dominance of the α-helix structure and temperature-dependent conformational change.     

Kinetic study on degradation of gaseous acetone over thin-film TiO2 photocatalyst in a continuous flow system

The effects of mixing condition by baffles, inlet concentration and face velocity on the photocatalytic degradation (PCD) of gaseous acetone over thin-film TiO₂ have been examined in a continuous flow system. The PCD rate increased upon installing baffles at a low inlet concentration and a high face velocity.     

New members of a class of iron-thiolate-nitrosyl compounds: trinuclear iron-thiolate-nitrosyl complexes containing Fe(3)S(6) core

The neutral trinuclear iron-thiolate-nitrosyl, [(ON)Fe(mu-S,S-C(6)H(4))](3) (1), and its oxidation product, [(ON)Fe(mu-S,S-C(6)H(4))](3)[PF(6)] (2), were synthesized and characterized by IR, X-ray diffraction, X-ray absorption, electron paramagnetic resonance (EPR), and magnetic measurement. The five-coordinated, square pyramidal geometry around each iron atom in complex 1 remains intact when complex 1 is oxidized to yield complex 2. Magnetic measurements and EPR results show that there is only one unpaired electron in complex 1 (S(total) = 1/2) and no unpaired electron (S(total) = 0) in 2. The detailed geometric comparisons between complexes 1 and 2 provide understanding of the role that the unpaired electron plays in the chemical bonding of this trinuclear complex. Significant shortening of the Fe-Fe, Fe-N, and Fe-S distances around Fe(1) is observed when complex 1 is oxidized to 2. This result implicates that the removal of the unpaired electron does induce the strengthening of the Fe-Fe, Fe-N, and Fe-S bonds in the Fe(1) fragment. A significant shift of the nuNO stretching frequency from 1751 cm(-1) (1) to 1821, 1857 cm(-1) (2) (KBr) also indicates the strengthening of the N-O bonds in complex 2. The EPR, X-ray absorption, magnetic measurements, and molecular orbital calculations lead to the conclusion that the unpaired electron in complex 1 is mainly allocated in the Fe(1) fragment and is best described as {Fe(1)NO}7, so that the unpaired electron is delocalized between Fe and NO via d-pi* orbital interaction; some contributions from [Fe(2)NO] and [Fe(3)NO] as well as the thiolates associated with Fe (1) are also realized. According to MO calculations, the spin density of complex 1 is predominantly located at the Fe atoms with 0.60, -0.15, and 0.25 at Fe(1), Fe(2), and Fe(3), respectively.     

Creating surfactant nanoparticles for block copolymer composites through surface chemistry

A simple strategy to tailor the surface of nanoparticles for their specific adsorption to and localization at block copolymer interfaces was explored. Gold nanoparticles coated by a mixture of low molecular weight thiol end-functional polystyrene (PS-SH) (Mn = 1.5 and 3.4 kg/mol) and poly(2-vinylpyridine) homopolymers (P2VP-SH) (Mn = 1.5 and 3.0 kg/mol) were incorporated into a lamellar poly(styrene-b-2-vinylpyridine) diblock copolymer (PS-b-P2VP) (Mn = 196 kg/mol). A library of nanoparticles with varying PS and P2VP surface compositions (FPS) and high polymer ligand areal chain densities was synthesized. The location of the nanoparticles in the PS-b-P2VP block copolymer was determined by transmission electron microscopy. Sharp transitions in particle location from the PS domain to the PS/P2VP interface, and subsequently to the P2VP domain, were observed at FPS = 0.9 and 0.1, respectively. This extremely wide window of FPS values where the polymer-coated gold nanoparticles adsorb to the interface suggests a redistribution of PS and P2VP polymers on the Au surface, inducing the formation of amphiphilic nanoparticles at the PS/P2VP interface. In a second and synthetically more challenging approach, gold nanoparticles were covered with a thiol terminated random copolymer of styrene and 2-vinylpyridine synthesized by RAFT polymerization. Two different random copolymers were considered, where the molecular weight was fixed at 3.5 kg/mol and the relative incorporation of styrene and 2-vinylpyridine repeat units varied (FPS = 0.52 and 0.40). The areal chain density of these random copolymers on Au is unfortunately not high enough to preclude any contact between the P2VP block of the block copolymer and the Au surface. Interestingly, gold nanoparticles coated by the random copolymer with FPS = 0.4 were dispersed in the P2VP domain, while those with FPS = 0.52 were located at the interface. A simple calculation for the adsorption energy to the interface of the nanoparticles with different surface arrangements of PS and P2VP ligands supports evidence for the rearrangement of thiol terminated homopolymers. An upper limit estimate of the adsorption energy of nanoparticles uniformly coated with a random arrangement of PS and P2VP ligands where a 10% surface area was occupied by P2VP -mers or chains was approximately 1 kBT, which indicates that such nanoparticles are unlikely to be segregated along the interface, in contrast to the experimental results for nanoparticles with mixed ligand-coated surfaces.     

Study on the Relationship between the Emission of Chlorine and UV/VIS Sensitive Organic Matter from Heating MSWI Baghouse Ash: Using an Optical UV/VIS Spectrometer as the On‐Line Monitoring Sensor

In this study the baghouse ash (fly ash) from municipal solid waste incineration (MSWI) plants was heated in a fixed bed reactor, from 25 °C to 800 °C. An optical fiber UV/VIS spectrometer was employed as the real‐time monitor to probe the emission behaviors of organic compounds. A two‐dimensional (2D) correlation technique was used to specify organic matter existing in exhausted gas. Three adsorbents, including water, acetone and cyclohexane, were used to adsorb the organic and molecular chlorine in the gas emitted from the reactor. Concentrations of molecular chlorine (Cl₂), total organic carbon (TOC), and total inorganic carbon (TIC) in these adsorbents were analyzed to evaluate the reactions occurring in fly ash. We have found that generation temperatures of molecular chlorine were found mainly at 200 °C and 750 °C, which are attributed to the dechlorination of chlorinated‐organic compounds and vaporization of heavy metal chlorides, respectively. 2D correlation UV/VIS spectra are useful to extract valuable information from the one‐dimensional UV/VIS of emitted gas. The identified organic species would be diethyl‐amine, dibenzo‐p‐dioxin, thioxanthone, 1,4‐dichloro‐anthraquinone, benzene, 1‐naphthalene azo, azulene, dibenzanthrone, 1‐chloro‐4‐notroso‐benzene and 4‐nitro‐toluene. The emission behaviors of dibenzo‐p‐dioxin, thioxanthone, azulene and dibenzanthrone were reported, and we concluded that the chlorine emission is almost always earlier than the release of these UV/VIS‐sensitive organic compounds.     

ON THE MULTIPLE CYCLES OF BACTERIORHODOPSIN AT HIGH pH

Bacteriorhodopsin (bR) shows at least two parallel photocycles at pH 10.5, suggesting that more than one form of bR exists in alkaline bR sample. Upon the absorption of visible light, the different forms of bR at high pH yield different parallel intermediates: M₄₁₂ with two rise and two decay components; and R, an extremely fast rising and extremely slow decaying intermediate with an absorption peak at 350 nm. The kinetics and spectra do not agree with the proposal of Kouyama el al. (1988, Biochemistry 27,5855–5863) that the 350 nm-absorbing species is the N intermediate which follows M₄₁₂ and that the slow decaying M₄₁₂ is an M-like photoproduct of N. Our results basically agree with the proposal of Dacshazy et al. (1988, Proc. Natl. Acad. Sci. USA 85,6358–6361) that the fast and slow decaying M₄₁₂ intermediates and R are in independent photocycles arising from different forms of bR. The different forms of bR are probably in dynamic equilibrium with their ratios controlled by pH and ionic strength.     

Simultaneous determination of niflumic acid and its prodrug, talniflumate in human plasma by high performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of niflumic acid and its prodrug, talniflumate, in human plasma. Niflumic acid and talniflumate were eluted isocratically with methanol-water (73:27, v/v, adjusted to pH 3.5 by acetic acid) at a fl ow rate of 1 mL/min. Indomethacin was used as an internal standard. Signals were monitored by an UV detector at 288 nm. Retention times of indomethacin, niflumic acid and talniflumate were 5.9, 7.2 and 13.5 min, respectively. Calibration plots were linear over the range 50-5000 ng/mL for niflumic acid and 100-5000 ng/mL for talniflumate. The limits of quantitation were 50 ng/mL for niflumic acid and 100 ng/mL for talniflumate. The intra- and inter-day relative standard deviations (RSD) of niflumic acid and talniflumate were less than 10% and the accuracies were higher than 90%. This method is rapid, sensitive and reproducible for the determination of niflumic acid and talniflumate in human plasma.     

Multifunctionality and crystal dynamics of a highly stable, porous metal-organic framework [Zn4O(NTB)2

A porous metal-organic framework [Zn(4)O(NTB)(2)].3DEF.EtOH (1), in which (3,6)-connected nets are doubly interpenetrated to generate curved three-dimensional channels, has been prepared. Framework 1 exhibits high permanent porosity (Langmuir surface area, 1121 m(2)/g; pore volume, 0.51 cm(3)/cm(3)), high thermal stability (up to 430 degrees C), high hydrogen adsorption capacity (1.9 wt % at 77 K and 1 atm), selective organic guest binding ability (K(f)()( )(): MeOH > pyridine > benzene > dodecane), and guest-dependent blue luminescence (lambda(max) depending on guest identity). Most interestingly, the framework sustains single crystallinity even at 400 degrees C and 10(-)(5) Torr, and the framework components undergo reversible dynamics, mainly rotational motion, in response to removal and rebinding of the guest molecules.