Synthesis, characterization, and DFT/TD-DFT calculations of highly phosphorescent blue light-emitting anionic iridium complexes

Highly phosphorescent blue-light-emitting anionic iridium complexes (C4H9)4N[Ir(2-phenylpyridine)2(CN)2] (1), (C4H9)4N[Ir(2-phenyl-4-dimethylaminopyridine)2(CN)2] (2), (C4H9)4N[Ir(2-(2,4-difluorophenyl)-pyridine)2(CN)2] (3), (C4H9)4N[Ir(2-(2,4-difluorophenyl)-4-dimethylaminopyridine)2(CN)2] (4), and (C4H9)4N[Ir(2-(3,5-difluorophenyl)-4-dimethylaminopyridine)2(CN)2] (5) were synthesized and characterized using NMR, UV-vis absorption, and emission spectroscopy and electrochemical methods. In these complexes color and quantum yield tuning aspects are demonstrated by modulating the ligands with substituting donor and acceptor groups on both the pyridine and phenyl moieties of 2-phenylpyridine. Complexes 1-5 display intense photoluminescence maxima in the blue region of the visible spectrum and exhibit very high phosphorescence quantum yields, in the range of 50-80%, with excited-state lifetimes of 1-4 micros in acetonitrile solution at 298 K. DFT and time dependent-DFT calculations were performed on the ground and excited states of the investigated complexes to provide insight into the structural, electronic, and optical properties of these systems.     

Different Faces of the Shearlet Group

Recently, shearlet groups have received much attention in connection with shearlet transforms applied for orientation sensitive image analysis and restoration. The square integrable representations of the shearlet groups provide not only the basis for the shearlet transforms but also for a very natural definition of scales of smoothness spaces, called shearlet coorbit spaces. The aim of this paper is twofold: first we discover isomorphisms between shearlet groups and other well-known groups, namely extended Heisenberg groups and subgroups of the symplectic group. Interestingly, the connected shearlet group with positive dilations has an isomorphic copy in the symplectic group, while this is not true for the full shearlet group with all nonzero dilations. Indeed we prove the general result that there exist, up to adjoint action of the symplectic group, only one embedding of the extended Heisenberg algebra into the Lie algebra of the symplectic group. Having understood the various group isomorphisms it is natural to ask for the relations between coorbit spaces of isomorphic groups with equivalent representations. These connections are examined in the second part of the paper. We describe how isomorphic groups with equivalent representations lead to isomorphic coorbit spaces. In particular we apply this result to square integrable representations of the connected shearlet groups and metaplectic representations of subgroups of the symplectic group. This implies the definition of metaplectic coorbit spaces. Besides the usual full and connected shearlet groups we also deal with Toeplitz shearlet groups.     

Variation of Loewner Chains,Extreme and Support Points in the Class $$S^0$$ in Higher Dimensions

We introduce a family of natural normalized Loewner chains in the unit ball, which we call “geräumig”—spacious—which allow us to construct, by means of suitable variations, other normalized Loewner chains which coincide with the given ones from a certain time on. We apply our construction to the study of support points, extreme points, and time-\(\log M\)-reachable mappings in the class \(S^0\) of mappings admitting parametric representation.     

Contact points and fractional singularities for semigroups of holomorphic self-maps of the unit disc

We study boundary singularities which can appear for infinitesimal generators of one-parameter semigroups of holomorphic self-maps of the unit disc. We introduce “regular” fractional singularities and characterize them in terms of the behavior of the associated semigroups and K?nigs functions. We also provide necessary and sufficient geometric criteria on the shape of the image of the K?nigs function for having such singularities. In order to do this, we study contact points of semigroups and prove that any contact (not fixed) point of a one-parameter semigroup corresponds to a maximal arc on the boundary to which the associated infinitesimal generator extends holomorphically as a vector field tangent to this arc.     

Global attractors for the coupled suspension bridge system with temperature

This paper deals with the long‐term properties of the thermoelastic nonlinear string‐beam system related to the well‐known Lazer–McKenna suspension bridge model (0.1) In particular, no mechanical dissipation occurs in the equations, because the loss of energy is entirely due to thermal effects. The existence of regular global attractors for the associated solution semigroup is proved (without resorting to a bootstrap argument) for time‐independent supplies f,g,h and any . Copyright © 2015 John Wiley & Sons, Ltd.     

CE assay of methylmalonyl-coenzyme-a mutase activity

Methylmalonyl-coenzyme A mutase (MCM) is a 5'-deoxyadenosylcobalamin-linked mitochondrial enzyme that catalyzes the isomerization of L-methylmalonyl-coenzyme A to succinyl-coenzyme A. We described a method for methylmalonyl-CoA and succinyl-CoA separation by CE, suitable for the evaluation of MCM activity. The working conditions for optimal separation were obtained in order to achieve the best resolution in the shortest analysis time. The optimization of buffer composition together with other variables, such as injection time, separation voltage, migration time, and capillary temperature, resulted in a solution of 30 mM NaH2PO4 containing 15 mM SDS, pH 3.2. Separations were carried out in an uncoated fused-silica capillary (55 cm, 50 microm id) at -25 kV, reading at 254 nm. The method performance was evaluated by measuring total and holo-MCM activity in biological matrices such as rat liver and human peripheral blood lymphocytes (PBL). The mean MCM activity was expressed in nmol/h/mg protein of tissue/cell extract and was calculated from the amount of reaction product formed. The rapidity of analysis and utmost precision (repeatability and within-laboratory reproducibility) point out the potentialities of the proposed method for the differential diagnosis of methylmalonic acidemia, in relation to protein or coenzyme defects.     

Embedding effects on charge-transport parameters in molecular organic materials

We present a generalized version of the tight-binding approach to determine the electronic coupling parameter in charge (hole) transport phenomena in organic materials. The main novelty of this approach is that the "embedding effects" of the environment (either a solvent or a crystal packing) can be explicitly included in the calculation by considering an embedded dimer. One of the main features shown by the application of the method to both model systems and oligoacene crystals is that the routinely used "energy splitting in a dimer" approximation gives reasonable results even if the transfer units are not equivalent by symmetry but the embedding effects are properly taken into account.     

Convenient route to enantiopure fmoc-protected morpholine-3-carboxylic acid

Enantiopure Fmoc-protected morpholine-3-carboxylic acid was synthesized from dimethoxyacetaldehyde and serine methyl ester through a short and practical synthetic route. The preparation consisted of a five-step process based on reductive amination, intramolecular acetalization, and concomitant elimination of the anomeric methoxy substituent, followed by hydrogenation of the double bond and final acidic ester hydrolysis. The optical purity of both enantiomers of the title amino acid was demonstrated by HPLC analysis of the corresponding amide derivatives obtained from coupling with chiral (S)-(-)-1-phenylethylamine. Moreover, the synthesis of a model tripeptide showed full compatibility of the title Fmoc-amino acid with solid-phase peptide synthesis, thus allowing the application of Fmoc-morpholine-3-carboxylic acid in peptidomimetic chemistry on the solid phase.