Multiscale charge injection and transport properties in self-assembled monolayers of biphenyl thiols with varying torsion angles

This article describes the molecular structure-function relationship for a series of biphenylthiol derivatives with varying torsional degree of freedom in their molecular backbone when self-assembled on gold electrodes. These biphenylthiol molecules chemisorbed on Au exhibit different tilt angles with respect to the surface normal and different packing densities. The charge transport through the biphenylthiol self-assembled monolayers (SAMs) showed a characteristic decay trend with the effective monolayer thickness. Based on parallel pathways model the tunneling decay factor β was estimated to be 0.27??(-1) . The hole mobility of poly(3-hexylthiophene)-based thin-film transistors incorporating a biphenylthiol SAM coating the Au source and drain electrodes revealed a dependence on the injection barrier with the highest occupied molecular orbital (HOMO) level of the semiconductor. The possible role of the resistivity of the SAMs on transistor electrodes on the threshold voltage shift is discussed. The control over the chemical structure, electronic properties, and packing order of the SAMs provides a versatile platform to regulate the charge injection in organic electronic devices.     

The exohedral Diels-Alder reactivity of the titanium carbide endohedral metallofullerene Ti2C2@D(3h)-C78: comparison with D(3h)-C78 and M3N@D(3h)-C78 (M=Sc and Y) reactivity

The chemical functionalization of endohedral (metallo)fullerenes has become a main focus of research in the last few years. It has been found that the reactivity of endohedral (metallo)fullerenes may be quite different from that of the empty fullerenes. Encapsulated species have an enormous influence on the thermodynamics, kinetics, and regiochemistry of the exohedral addition reactions undergone by these species. A detailed understanding of the changes in chemical reactivity due to incarceration of atoms or clusters of atoms is essential to assist the synthesis of new functionalized endohedral fullerenes with specific properties. Herein, we report the study of the Diels-Alder cycloaddition between 1,3-butadiene and all nonequivalent bonds of the Ti(2)C(2)@D(3h)-C(78) metallic carbide endohedral metallofullerene (EMF) at the BP86/TZP//BP86/DZP level of theory. The results obtained are compared with those found by some of us at the same level of theory for the D(3h)-C(78) free cage and the M(3)N@D(3h)-C(78) (M=Sc and Y) metallic nitride EMFs. It is found that the free cage is more reactive than the Ti(2)C(2)@D(3h)-C(78) EMF and this, in turn, has a higher reactivity than M(3)N@D(3h)-C(78). The results indicate that, for Ti(2)C(2)@D(3h)-C(78), the corannulene-type [5,6] bonds c and f, and the type B [6,6] bond 3 are those thermodynamically and kinetically preferred. In contrast, the D(3h)-C(78) free cage has a preference for addition to the [6,6] 1 and 6 bonds and the [5,6] b bond, whereas M(3)N@D(3h)-C(78) favors additions to the [6,6] 6 (M=Sc) and [5,6] d (M=Y) bonds. The reasons for the regioselectivity found in Ti(2)C(2)@D(3h)-C(78) are discussed.     

Potential and limitations of ensemble docking

A major problem in structure-based virtual screening applications is the appropriate selection of a single or even multiple protein structures to be used in the virtual screening process. A priori it is unknown which protein structure(s) will perform best in a virtual screening experiment. We investigated the performance of ensemble docking, as a function of ensemble size, for eight targets of pharmaceutical interest. Starting from single protein structure docking results, for each ensemble size up to 500,000 combinations of protein structures were generated, and, for each ensemble, pose prediction and virtual screening results were derived. Comparison of single to multiple protein structure results suggests improvements when looking at the performance of the worst and the average over all single protein structures to the performance of the worst and average over all protein ensembles of size two or greater, respectively. We identified several key factors affecting ensemble docking performance, including the sampling accuracy of the docking algorithm, the choice of the scoring function, and the similarity of database ligands to the cocrystallized ligands of ligand-bound protein structures in an ensemble. Due to these factors, the prospective selection of optimum ensembles is a challenging task, shown by a reassessment of published ensemble selection protocols.     

Classical driven transport in open systems with particle interactions and general couplings to reservoirs

We study nonequilibrium steady states of lattice gases with nearest-neighbor interactions that are driven between two reservoirs. Density profiles in these systems exhibit oscillations close to the reservoirs. We demonstrate that an approach based on time-dependent density functional theory copes with these oscillations and predicts phase diagrams of bulk densities to a good approximation under arbitrary boundary-reservoir couplings. The minimum or maximum current principles can be applied only for specific bulk-adapted couplings. We show that they generally fail to give the correct topology of phase diagrams but can still be useful for getting insight into the mutual arrangement of different phases.     

Models in Boundary Quantum Field Theory Associated with Lattices and Loop Group Models

In this article we give new examples of models in boundary quantum field theory, i.e. local time-translation covariant nets of von Neumann algebras, using a recent construction of Longo and Witten, which uses a local conformal net on the real line together with an element of a unitary semigroup associated with . Namely, we compute elements of this semigroup coming from H?lder continuous symmetric inner functions for a family of (completely rational) conformal nets which can be obtained by starting with nets of real subspaces, passing to its second quantization nets and taking local extensions of the former. This family is precisely the family of conformal nets associated with lattices, which as we show contains as a special case the level 1 loop group nets of simply connected, simply laced groups. Further examples come from the loop group net of at level 2 using the orbifold construction.     

Glass-forming ability of soda lime borate liquids

We investigate the composition dependence of glass-forming ability (GFA) of a series of iron-containing soda lime borate liquids by substituting Na₂O for B₂O₃. We have characterized GFA by measuring the glass stability against crystallization using a differential scanning calorimeter (DSC). The results show that the GFA decreases when substituting Na₂O for B₂O₃. Moreover, we find that there is no direct link between the kinetic fragility and GFA for the soda lime borate series studied herein. We have also discovered and clarified a striking thermal history dependence of the glass stability against crystallization. In particular, the two glasses containing 20 and 25 Na₂O mol% do not exhibit crystallization exotherms during the second DSC upscan at 10 and 20 K/min following prior slow (10 and 20 K/min) downscans. This indicates that the glass stability of these compositions can be enhanced by cooling their melts to the glassy state slowly, before any reheating. We explain this phenomenon in terms of the thermal history dependence of boron speciation.     

On the Banach ⁎-algebra crossed product associated with a topological dynamical system

Given a topological dynamical system $\Sigma =(X,\sigma )$, where X is a compact Hausdorff space and σ a homeomorphism of X, we introduce the Banach ^?-algebra crossed product ${?}^1(\Sigma )$ most naturally associated with Σ and initiate its study. It has a richer structure than its well investigated $C^{?}$-envelope, as becomes evident from the possible existence of non-self-adjoint closed ideals. We link its ideal structure to the dynamics, determining when the algebra is simple, or prime, and when there exists a non-self-adjoint closed ideal. A structure theorem is obtained when X consists of one finite orbit, and the algebra is shown to be Hermitian if X is finite. The key lies in analysing the commutant of $C(X)$ in the algebra, which is shown to be a maximal abelian subalgebra with non-zero intersection with each non-zero closed ideal.     

Synthesis of a soluble poly(fluorenone)

The synthesis and characterisation of a soluble poly(fluorenone) is presented, a polymer with high electron affinity with potential for use in plastic electronic devices as an n-type material.     

A quinhydrone-type 2 ratio 1 acceptor-donor charge transfer complex obtained via a solvent-free reaction

A 2 : 1 2-methoxybenzoquinone (BQ(OMe))-hydroquinone (H2Q) complex (5), obtained as single crystals by a solvent-free reaction, combines dipolar and pi-pi interactions, as well as hydrogen bonding.