Regioisomerism in cationic sulfonyl-substituted [Ir(C^N)2(N^N)]+ complexes: its influence on photophysical properties and LEC performance

In a series of regioisomeric [Ir(C^N) 2 (bpy)] + complexes containing methylsulfonyl groups on the cyclometallating ligands, the influence of the substitution position on photophysical, electrochemical and LEC device properties is investigated

Redox cycling of iridium(III) complexes gives versatile materials for photonics applications

The cyclometallated iridium(III) complex [Me4N][Ir(ppy)2(cat)] (Hppy = 2-phenylpyridine; H2cat = benzene-1,2-diol) has been prepared under inert atmosphere and has been structurally characterized by single crystal X-ray diffraction. Under ambient conditions, the fully reduced complex (as formulated) undergoes rapid one-electron oxidation both in solution and in the solid state to a species containing a semiquinone ligand. The resultant neutral complex [Ir(ppy)2(sq)] (sq = o-semiquinone) was also prepared by exposing the reaction mixture to O2 during the course of the reaction. Electron paramagnetic resonance (EPR) spectroscopy confirms the diamagnetic nature of the complex [Me4N][Ir(ppy)2(cat)] and indicates that the unpaired electron in [Ir(ppy)2(sq)] resides primarily on the sq ligand. The photophysical, electrochemical, and spectroelectrochemical properties of [Ir(ppy)2(sq)] were investigated and reveal the changes in absorption as the complex is converted into the catecholate and quinone forms

On ordinal utility, cardinal utility, and random utility

Though the Random Utility Model (RUM) was conceived  entirely in terms of ordinal utility, the apparatus throughwhich it is widely practised exhibits properties of  cardinal utility.  The adoption of cardinal utility as a  working operation of ordinal is perfectly valid, provided  interpretations drawn from that operation remain faithful  to ordinal utility.  The paper considers whether the latterrequirement holds true for several measurements commonly  derived from RUM.  In particular it is found that  measurements of consumer surplus change may depart from  ordinal utility, and exploit the cardinality inherent in  the practical apparatus.

Modular synthesis of simple cycloruthenated complexes with state-of-the-art performance in p-type DSCs

A modular approach based on Suzuki-Miyaura cross coupling and Miyaura borylation has been used to prepare two cyclometallated [Ru(N^N) 2 (C^N)] + complexes which possess either a carboxylic or phosphonic acid group attached via a phenylene spacer to the 4-position of the pyridine ring in the C^N ligand. The key intermediate in the synthetic pathway is [Ru(bpy) 2 ( 1 )] + where bpy = 2,2'-bipyridine and H 1 is 4-chloro-2-phenylpyridine. The crystal structure of [Ru(bpy) 2 ( 1 )][PF 6 ] is presented. Reaction of [Ru(bpy) 2 ( 1 )][PF 6 ] with 4-carboxyphenylboronic acid leads to [Ru(bpy) 2 (H 6 )][PF 6 ], while the phosphonic acid analogue is isolated as the zwitterion [Ru(bpy) 2 (H 5 )]. The cyclometallated complexes have been characterized by mass spectrometry, multinuclear NMR spectroscopy, absorption spectroscopy and electrochemistry. [Ru(bpy) 2 ( 5 )] adsorbs onto NiO FTO/NiO electrodes (confirmed by solid-state absorption spectroscopy) and its performance in p-type dye-sensitized solar cells (DSCs) has been compared to that of the standard dye P1; two-screen printed layers of NiO give better DSC performances than one layer. Duplicate DSCs containing [Ru(bpy) 2 (H 5 )] achieve short-circuit current densities ( J SC ) of 3.38 and 3.34 mA cm –2 and photoconversion efficiencies ( η ) of 0.116 and 0.109%, respectively, compared to values of J SC = 1.84 and 1.96 mA cm –2 and η = 0.057 and 0.051% for P1. Despite its simple dye structure, the performance of [Ru(bpy) 2 (H 5 )] parallels the best-performing cyclometallated ruthenium(II) dye in p-type DSCs reported previously (He et al , J. Phys. Chem. C , 2014, 118 , 16518) and confirms the effectiveness of a phosphonic acid anchor in the dye and the attachment of the anchoring unit to the pyridine (rather than phenyl) ring of the cyclometallating ligan

Accessibility appraisal of integrated land-use-transport strategies: methodology and case study for the Netherlands Randstad area

Conventional approaches to measuring accessibility benefits are not capable of fully measuring the total accessibility benefits of integrated land-use-transport strategies, in which both land-use and transport changes form part of the policy strategy. In this paper a comprehensive methodology for analysing accessibility impacts and accessibility benefits, which is based on location-based and utility-based accessibility measures within an integrated land-use-transport interaction modelling framework, is described and applied in a case study. The case study examines the accessibility benefits and related user benefits of intensive mixed-use strategies aimed at increasing the density and diversity of activities around railway stations for the Randstad area of the Netherlands for the 1996-2030 period. A heavy concentration of activities near railway stations is shown to result in decreasing marginal returns for public-transport users and disbenefits for car users. © 2006 a Pion publication printed in Great Britain

Scalable, Economical, and Practical Synthesis of 4-(Difluoromethyl)pyridin-2-amine, a Key Intermediate for Lipid Kinase Inhibitors

A new, scalable, rapid, high yielding, and practical synthesis of 4-(difluoromethyl)pyridin-2-amine provides a key intermediate for the preparation of numerous protein kinase inhibitors and clinical candidates targeting phosphoinositide 3-kinase (PI3K) and the mechanistic target of rapamycin (mTOR) kinase. Starting from 2,2-difluoroacetic anhydride, an efficient five-step and two-pot procedure to prepare 4-(difluoromethyl)pyridin-2-amine (1) has been developed. Noteworthy aspects of this strategy include the avoidance of an amination process using a sealed vessel. Each step of the synthetic route has been optimized, and key intermediates have been isolated and characterized prior to the final two-pot procedure, which has been successfully applied for large-scale production

Search for a bound di-neutron by comparing 3^3He(e,e'p)d and 3^3H(e,e'p)X measurements

We report on a search for a bound di-neutron by comparing electron-induced proton-knockout $(e,e'p)$ measurements from Helium-3 ($^3$He) and Tritium ($^3$H). The measurements were performed at Jefferson Lab Hall A with a 4.326 GeV electron beam, and kinematics of large momentum transfer $Q^2 \approx 1.9$ (GeV/$c$)$^2$ and $x_B>1$, to minimize contributions from non quasi-elastic (QE) reaction mechanisms. Analyzing the measured $^3$He missing mass ($M_{miss}$) and missing energy ($E_{miss}$) distributions, we can distinguish the two-body break-up reaction, in which the residual proton-neutron system remains bound as a deuteron. In the $^3$H mirror case, under the exact same kinematic conditions, we do not identify a signature for a bound di-neutron with similar binding energy to that of the deuteron. We calculate exclusion limits as a function of the di-neutron binding energy and find that, for binding equivalent to the deuteron, the two-body break-up cross section on $^3$H is less than 0.9% of that on $^3$He in the measured kinematics at the 95% confidence level.Comment: 6 pages, 3 figure

The Amidase Domain of Lipoamidase Specifically Inactivates Lipoylated Proteins In Vivo

BACKGROUND:In the 1950s, Reed and coworkers discovered an enzyme activity in Streptococcus faecalis (Enterococcus faecalis) extracts that inactivated the Escherichia. coli and E. faecalis pyruvate dehydrogenase complexes through cleavage of the lipoamide bond. The enzyme that caused this lipoamidase activity remained unidentified until Jiang and Cronan discovered the gene encoding lipoamidase (Lpa) through the screening of an expression library. Subsequent cloning and characterization of the recombinant enzyme revealed that lipoamidase is an 80 kDa protein composed of an amidase domain containing a classic Ser-Ser-Lys catalytic triad and a carboxy-terminal domain of unknown function. Here, we show that the amidase domain can be used as an in vivo probe which specifically inactivates lipoylated enzymes. METHODOLOGY/PRINCIPAL FINDINGS:We evaluated whether Lpa could function as an inducible probe of alpha-ketoacid dehydrogenase inactivation using E. coli as a model system. Lpa expression resulted in cleavage of lipoic acid from the three lipoylated proteins expressed in E. coli, but did not result in cleavage of biotin from the sole biotinylated protein, the biotin carboxyl carrier protein. When expressed in lipoylation deficient E. coli, Lpa is not toxic, indicating that Lpa does not interfere with any other critical metabolic pathways. When truncated to the amidase domain, Lpa retained lipoamidase activity without acquiring biotinidase activity, indicating that the carboxy-terminal domain is not essential for substrate recognition or function. Substitution of any of the three catalytic triad amino acids with alanine produced inactive Lpa proteins. CONCLUSIONS/SIGNIFICANCE:The enzyme lipoamidase is active against a broad range of lipoylated proteins in vivo, but does not affect the growth of lipoylation deficient E. coli. Lpa can be truncated to 60% of its original size with only a partial loss of activity, resulting in a smaller probe that can be used to study the effects of alpha-ketoacid dehydrogenase inactivation in vivo