Efficient greenish blue electrochemiluminescence from fluorene and spirobifluorene derivatives

The spectroscopic and electrochemical behavior as well as electrogenerated chemiluminescence (ECL) of a series of donor-π-donor derivatives bearing triphenylamine groups as donor connected to a fluorene, 2,7-bis-(4-(N,N-diphenylamino)phen-1-yl)-9,9'-dimethylfluorene (1), or spirobifluorene core, 2,7-bis-(4-(N,N-diphenylamino)phen-1-yl)-9,9'-spirobifluorene (2) and 2,2',7,7'-tetrakis(4-(N,N-diphenylamino)phen-1-yl)-9,9'-spirobifluorene (3), were investigated. Besides a high photoluminescence (PL) quantum yield in solution (between 81 and 87%), an efficient radical ions annihilation process induces intense greenish blue ECL emission that could be seen with the naked eye. Only the tetrasubstituted spirobifluorene derivative (compound 3) shows weak ECL obtained by a direct annihilation mechanism. Because the energy of the annihilation reaction is higher than the energy required to form the singlet excited state, the S-route could be considered the pathway followed by the ECL process in these molecules. The ECL emissions recorded by direct ion-ion annihilation show two bands compared to the single structureless PL band. The ECL spectra obtained by a coreactant approach using benzoylperoxide as a coreagent show no differences relative to that produced by annihilation, except for an increasing of ECL intensity for all compounds.     

Non-divisibility and non-Markovianity in a Gaussian dissipative dynamics

We study a stochastic Schrödinger equation that generates a family of Gaussian dynamical maps in one dimension permitting a detailed exam of two different definitions of non-Markovianity: one related to the explicit dependence of the generator on the starting time, the other to the non-divisibility of the time-evolution maps. The model shows instances where one has non-Markovianity in both senses and cases when one has Markovianity in the second sense but not in the first one.     

An efficient mixed-ligand Pd catalytic system to promote C-N coupling for the synthesis of N-arylaminotriazole nucleosides

Make it unique! A mixed-ligand system of Pd/Synphos/Xantphos promotes effective C-N coupling in the synthesis of various N-arylaminotriazole and N-arylaminopurine nucleoside analogues. This catalytic system is strikingly powerful and efficient, allowing for unparalleled substrate scope and high product yields as well as promotion of C-Cl bond activation for C-N coupling (see scheme).     

The Monge problem in Wiener space

We address the Monge problem in the abstract Wiener space and we give an existence result provided both marginal measures are absolutely continuous with respect to the infinite dimensional Gaussian measure γ.     

Bis(4‐methylphenylsulfonyl)amino 4‐methylbenzenesulfonate: a new member of the (RSO2)ON(SO2R)2 family

The title compound, C₂₁H₂₁NO₇S₃, consists of an SO₂ON(SO₂)₂ central fragment and three terminal 4‐methylphenyl groups each attached at a sulfonyl S atom. The most obvious characteristic is the presence of two nearly face‐to‐face benzene rings, with their centroids separated by a rather short distance [3.7808 (18) Å], but with a rather slanted relative orientation [dihedral angle = 20.63 (13)°] so as to preclude a strong intramolecular π–π interaction. The third benzene ring is nearly perpendicular to the other two [dihedral angles = 71.62 (14) and 70.4 (13)°]. The packing of the structure is directed by two C—H...O hydrogen bonds involving aromatic H atoms (methyl H atoms are strictly non‐interacting), which define chains running in the [100] direction. These one‐dimensional chains evolve parallel to each other and exhibit no significant lateral interactions.     

Pairs of positive periodic solutions of second order nonlinear equations with indefinite weight

We study the problem of the existence and multiplicity of positive periodic solutions to the scalar ODE$u^{″}+\lambda a(t)g(u)=0,\lambda >0,$ where $g(x)$ is a positive function on ${\mathbb{R}}^{+}$, superlinear at zero and sublinear at infinity, and $a(t)$ is a T-periodic and sign indefinite weight with negative mean value. We first show the nonexistence of solutions for some classes of nonlinearities $g(x)$ when λ is small. Then, using critical point theory, we prove the existence of at least two positive T-periodic solutions for λ large. Some examples are also provided.     

A one-dimensional coagulation–fragmentation process with a dynamical phase transition

We introduce a reversible Markovian coagulation–fragmentation process on the set of partitions of {1,…,L}$\{1,\dots ,L\}$ into disjoint intervals. Each interval can either split or merge with one of its two neighbors. The invariant measure can be seen as the Gibbs measure for a homogeneous pinning model (Giacomin (2007) [10]). Depending on a parameter λ$\lambda$, the typical configuration can be either dominated by a single big interval (delocalized phase), or composed of many intervals of order 1$1$ (localized phase), or the interval length can have a power law distribution (critical regime). In the three cases, the time required to approach equilibrium (in total variation) scales very differently with L$L$. In the localized phase, when the initial condition is a single interval of size L$L$, the equilibration mechanism is due to the propagation of two “fragmentation fronts” which start from the two boundaries and proceed by power-law jumps.     

Hamiltonian structural analysis of curved beams with or without generalized two-parameter foundation

The solution of curved Timoshenko beams with or without generalized two-parameter elastic foundation is presented. Beam can be subjected to any kind of loads and imposed external actions, distributed or concentrated along the beam. It can have external and internal restraints and any kind of internal kinematical or mechanical discontinuity. Moreover, the beam may have any spatial curved geometry, by dividing the entire structure into segments of constant curvature and constant elastic properties, each segment resting or not on elastic foundation. The foundation has six parameters like a generalized Winkler soil with the addition of other two parameters involving the link between settlements in transverse direction, as occurs for Pasternak soil model. The solution is obtained by the Hamiltonian structural analysis method, based on an energetic approach, solving a mixed canonical Hamiltonian system of twelve differential equations, leading to the fundamental matrix. The solution, numerically expressed or in closed form, is fast and simple to be implemented on a software, being the solving matrix always of order 12 for any kind of geometry and loads, without increasing in computational complexity. Numerical examples are given, comparing the results of the proposed procedure with the literature data, for rectilinear and curved beams with different soil properties.