Ni( ii ) complexes of the phosphine-oxime Ph 2 PC 6 H 4 -2-CH₌NOH
We report the solution and structural chemistry of nickel( ii ) complexes of the phosphine-oxime Ph 2 PC 6 H 4 -2-CH₌NOH (PCH₌NOH).
Chemistry↗
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Cobalt complexes of the chelating dicarboxylate ligand “esp”: a paddlewheel-type dimer and a heptanuclear coordination cluster
Reaction of CoCO 3 with α,α,α′,α′-tetramethyl-1,3-benzenedipropionic acid (H 2 esp) in EtOH forms the paddlewheel-type dimer Co 2 (esp) 2 (EtOH) 2 , which hydrolyzes in MeCN to give a bowl-shaped heptacobalt coordination cluster complex; both compounds display antiferromagnetic interactions between high-spin Co( ii ) ions.
Pakula, Ryan J.↗
Steric control of dioxygen activation pathways for Mn II complexes supported by pentadentate, amide-containing ligands
Steric control of dioxygen activation is demonstrated through O 2 titration and isotopic labeling experiments for two Mn( ii ) complexes.
Parham, Joshua D.↗
Effect of ligand substituents on nickel and copper [N 4 ] complexes: electronic and redox behavior, and reactivity towards protons
The ligand substituents have a major effect on the redox potentials, catalytic efficiency and robustness of the complexes in HER.
Kankanamalage, Pavithra H. A.↗
Chicken fat for catalysis: a scaffold is as important for molecular complexes for energy transformations as it is for enzymes in catalytic function
Metalloenzymes are remarkably active, specific, and efficient catalysts.Mimicking the active sites with organometallic complexes based on crystal structures has been a focus for many synthetic chemists. These surrogates have provided significant mechanistic insight into both the molecular complexes as well as the enzymes, however, one of the principle findings has been that just reproducing the active site is not adequate in reproducing the catalytic function. Specifically, the scaffold surrounding the active site plays a critical role in many aspects of catalysis, from positioning reactants optimally to positioning functional groups for reaction to creating the ideal environment for catalysis. Each of these can be controlled with both static positioning as well as small and large dynamics that can activate or control a specific part of the reaction. In this review, we will discuss the effect of organic/peptidic scaffolds, along with medium as an extension of the scaffold, and their varying impacts on catalytic reactivity.
Laureanti, Joseph A.↗
A zinc( II ) complex of di(naphthylethynyl)azadipyrromethene with low synthetic complexity leads to OPV with high industrial accessibility
Organic photovoltaics have reached high power conversion efficiencies (PCE) using non-fullerene acceptors (NFAs). However, the best NFAs tend to have complex syntheses, limiting scalability. Among polymer donors, regioregular poly(3-hexylthiophene) (P3HT) has the greatest potential for commercialization due to its simple synthesis and good stability, but PCEs have been limited. It is thus imperative to find scalable NFAs that give high PCE with P3HT. Herein we report a zinc( II ) complex of di(naphthylethynyl)azadipyrromethene (Zn(L2) 2 ) as a non-planar NFA that can be synthesized on the gram scale using inexpensive starting materials without chromatography column purification. The NFA has strong absorption in the 600–800 nm region. Time-dependent density-functional theory calculations suggest that the low-energy absorptions can be understood within a four-orbital model involving transitions between π-orbitals on the azadipyrromethene core. OPVs fabricated from P3HT:Zn(L2) 2 blends reached a PCE of 5.5%, and the PCE was not very sensitive to the P3HT:Zn(L2) 2 weight ratio. Due to its shape, Zn(L2) 2 shows isotropic charge transport and its potential as an electron donor is also demonstrated. The combination of simple synthesis, good PCE and photostability, and tolerance to the active material weight ratio demonstrates the potential of Zn(L2) 2 as an active layer material in OPVs.
36 MATERIALS SCIENCE↗
Tuning the excited-state deactivation pathways of dinuclear ruthenium( ii ) 2,2′-bipyridine complexes through bridging ligand design
A detailed photophysical study of binuclear complexes was performed using steady-state and time-resolved photoluminescence measurements at variable temperature. The results were compared with the prototypical [Ru(bpy) 3 ] 2+ .
Cerfontaine, Simon↗
Electrocatalytic syngas generation with a redox non-innocent cobalt 2-phosphinobenzenethiolate complex
A cobalt complex supported by the 2-(diisopropylphosphaneyl)benzenethiol ligand was synthesized and its electronic structure and reactivity were explored.
Orchanian, Nicholas M.↗
Comparing coordination uranyl( vi ) complexes with 2-(1 H -imidazo[4,5- b ]phenazin-2-yl)phenol and derivatives
The synthesis, characterization, emission, and electronic spectroscopy for complexes of derivatives of 2-(1 H -imidazo[4,5- b ]phenazin-2-yl)phenol with uranyl (UO 2 2+ ) and copper (Cu 2+ ) are detailed.
Hiti, E. A.↗
Synthesis of a series of M( ii ) (M = Mn, Fe, Co) chloride complexes with both inter- and intra-ligand hydrogen bonding interactions
Hydrogen bonding networks are vital for metallo-enzymes to function; however, modeling these systems is non-trivial. The development of 1st-row transition metal chloride complexes with intramolecular hydrogen-bonding interactions are detailed herein.
Leahy, Clare A.↗
Optimal system size for complex dynamics in random neural networks near criticality
In this article, we consider a model of dynamical agents coupled through a random connectivity matrix, as introduced by Sompolinsky et al. [Phys. Rev. Lett. 61(3), 259–262 (1988)] in the context of random neural networks. When system size is infinite, it is known that increasing the disorder parameter induces a phase transition leading to chaotic dynamics. We observe and investigate here a novel phenomenon in the sub-critical regime for finite size systems: the probability of observing complex dynamics is maximal for an intermediate system size when the disorder is close enough to criticality. We give a more general explanation of this type of system size resonance in the framework of extreme values theory for eigenvalues of random matrices.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Squeezed states and Hermite polynomials in a complex variable
Following the lines of the recent paper of J.-P. Gazeau and F. H. Szafraniec [J. Phys. A: Math. Theor. 44, 495201 (2011)], we construct here three types of coherent states, related to the Hermite polynomials in a complex variable which are orthogonal with respect to a non-rotationally invariant measure. We investigate relations between these coherent states and obtain the relationship between them and the squeezed states of quantum optics. We also obtain a second realization of the canonical coherent states in the Bargmann space of analytic functions, in terms of a squeezed basis. All this is done in the flavor of the classical approach of V. Bargmann [Commun. Pure Appl. Math. 14, 187 (1961)].
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Wind power curve modeling in complex terrain using statistical models
The simplest power curves model wind power only as a function of the wind speed at the turbine hub height. While the latter is an essential predictor of power output, wind speed information in other parts of the vertical profile, as well as additional atmospheric variables, are also important determinants of power. The goal of this work was to determine the gain in predictive ability afforded by adding wind speed information at other heights, as well as other atmospheric variables, to the power prediction model. Using data from a wind farm with a moderately complex terrain in the Altamont Pass region in California, we trained three statistical models—a neural network, a random forest and a Gaussian process model—to predict power output from various sets of aforementioned predictors. The comparison of these predictions to the observed power data revealed that considerable improvements in prediction accuracy can be achieved both through the addition of predictors other than the hub-height wind speed and the use of statistical models. To our knowledge, the use of the Gaussian process model in this context is new, in contrast to neural networks and random forests. The advantage of this model over the other two models is that it provides a much more natural way to estimate the uncertainty associated with its predictions. In addition, this study presents one of the most comprehensive analyses to date of the relative importance of various wind power curve inputs.
Bulaevskaya, V.↗
Restricted Hartree Fock using complex-valued orbitals: A long-known but neglected tool in electronic structure theory
Restricted Hartree Fock using complex-valued orbitals (cRHF) is studied. We introduce an orbital pairing theorem, with which we obtain a concise connection between cRHF and real-valued RHF, and use it to uncover the close relationship between cRHF, unrestricted Hartree Fock, and generalized valence bond perfect pairing. This enables an intuition for cRHF, contrasting with the generally unintuitive nature of complex orbitals. We also describe an efficient computer implementation of cRHF and its corresponding stability analysis. By applying cRHF to the Be + H{sub 2} insertion reaction, a Woodward-Hoffmann violating reaction, and a symmetry-driven conical intersection, we demonstrate in genuine molecular systems that cRHF is capable of removing certain potential energy surface singularities that plague real-valued RHF and related methods. This complements earlier work that showed this capability in a model system. We also describe how cRHF is the preferred RHF method for certain radicaloid systems like singlet oxygen and antiaromatic molecules. For singlet O{sub 2}, we show that standard methods fail even at the equilibrium geometry. An implication of this work is that, regardless of their individual efficacies, cRHF solutions to the HF equations are fairly commonplace.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
A liquid jet setup for x-ray scattering experiments on complex liquids at free-electron laser sources
In this paper we describe a setup for x-ray scattering experiments on complex fluids using a liquid jet. The setup supports Small and Wide Angle X-ray Scattering (SAXS/WAXS) geometries. The jet is formed by a gas-dynamic virtual nozzle (GDVN) allowing for diameters ranging between 1 μm and 20 μm at a jet length of several hundred μm. To control jet properties such as jet length, diameter, or flow rate, the instrument is equipped with several diagnostic tools. Three microscopes are installed to quantify jet dimensions and stability in situ. The setup has been used at several beamlines performing both SAXS and WAXS experiments. As a typical example we show an experiment on a colloidal dispersion in a liquid jet at the X-ray Correlation Spectroscopy instrument at the Linac Coherent Light Source free-electron laser.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Synthesis and characterization of an amethyrin-uranyl complex displaying aromatic character
The reaction among amethyrin and non-aqueous uranyl silylamide (UO2[N(SiMe 3 ) 2 ] 2 ) under anaerobic conditions afford a bench-stable uranyl complex. UV-Vis spectroscopy, cyclic voltammetry, as well as proton NMR spectroscopic analyses offer support for the conclusion that all six pyrrole subunits participate in coordination of the uranyl dication and that, upon complexation, the amethyrin-core undergoes a 2-electron oxidation to yield a formal 22 π-electron aromatic species.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Structural complexity in the f -block: small deviations of the complexation of lanthanides by O,Oʹ -diethylmonothiophosphate
Dithiophosphinic acids undergo radiolytic degradation during the extraction of actinides in used nuclear fuel. These will degrade into monothiophosphinic acids and then to phosphinic acids. To elucidate how the complexes that are formed during these radioactive separations change as the ligand degrades, the mixed donor ligand O,O′- diethylmonothiophosphate is chosen as an analog for the monothiophosphinic intermediate. Herein, the monothiophosphate complexes Ln 2 (OPS(OEt) 2 ) 6 (H 2 O) 8 (Ln = La) (La 2 L 6 H 2 O), Ln 2 (OPS(OEt) 2 ) 6 (EtOH) 4 (Ln = La) (La 2 L 6 EtOH), K 2 [Ln(OPS(OEt) 2 ) 5 (H 2 O) 2 ]·H 2 O·CH 2 Cl 2 , (Ln = Ce) (CeL 5 -α), K 2 [Ln(OPS(OEt) 2 ) 5 (H 2 O) 2 ]·H 2 O·CH 2 Cl 2 , (Ln = Pr) (PrL 5 -β), K[Ln(OPS(OEt) 2 ) 4 (H 2 O) 3 ], (Ln = Pr, Sm-Er) (ML 4 ), and K 3 [Ln(OPS(OEt) 2 ) 6 ], (Ln = Dy) (DyL 6 ) were synthesized and characterized using single-crystal X-ray diffraction and optical spectroscopy. Although the lanthanides contract in a nearly linear fashion, the structural changes observed as the f-block is traversed in these compounds are not necessarily a hard line but more so a blend of different structure types possible for each f-element. Furthermore, comparison of the Ln−O bond lengths shows a nearly linear contraction, but the Ln−S bond lengths do not monotonically decrease because of the hard Lewis acidity of the Ln 3+ cations.
37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗
Quantum simulator of an open quantum system using superconducting qubits: exciton transport in photosynthetic complexes
Open quantum system approaches are widely used in the description of physical, chemical and biological systems. A famous example is electronic excitation transfer in the initial stage of photosynthesis, where harvested energy is transferred with remarkably high efficiency to a reaction center. This transport is affected by the motion of a structured vibrational environment, which makes simulations on a classical computer very demanding. Here we propose an analog quantum simulator of complex open system dynamics with a precisely engineered quantum environment. Our setup is based on superconducting circuits, a well established technology. As an example, we demonstrate that it is feasible to simulate exciton transport in the Fenna–Matthews–Olson photosynthetic complex. Our approach allows for a controllable single-molecule simulation and the investigation of energy transfer pathways as well as non-Markovian noise-correlation effects.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗