Very long-distance magnetic coupling in a dicopper(II) metallacyclophane with extended π-conjugated diphenylethyne bridges

Self-assembly of the rigid rodlike ligand N,N'-4,4'-diphenylethynebis(oxamate) (dpeba) and Cu(2+) ions affords a novel dinuclear copper(II) metallacyclophane (nBu(4)N)(4)[Cu(2)(dpeba)(2)]·4MeOH·2Et(2)O (1) featuring a very long intermetallic distance (r = 15.0 ?). Magnetic susceptibility measurements for 1 reveal a moderately weak but nonnegligible intramolecular antiferromagnetic coupling between the two metal centers across the double para-substituted diphenylethynediamidate bridge (J = -3.9 cm(-1); H = -JS(1)S(2), where S(1) = S(2) = S(Cu) = (1)/(2)). Density functional electronic structure calculations on 1 support the occurrence of a spin polarization mechanism.     

Binaphthyl platform as starting materials for the preparation of electron rich benzo[g,h,i]perylenes. Application to molecular architectures based on amino benzo[g,h,i]perylenes and carborane combinations

Valuable amino benzo[g,h,i]perylenes have been obtained through a one pot electrophilic aromatic substitution--Scholl reaction sequence. Novel molecular architectures combining 3D-o-carborane and planar amino benzo[g,h,i]perylene units are described. Photophysical properties of amino benzo[g,h,i]perylene and the carborane-appended derivatives are discussed.     

The fate of optical excitations in small hydrated ZnS clusters: a theoretical study into the effect of hydration on the excitation and localisation of electrons in Zn4S4 and Zn6S6

In this paper we explore the effect of water on the excited state properties of ZnS nanostructures by means of time-dependent density functional theory (TD-DFT) calculations. Using these TD-DFT calculations we show that the effect of water on the optical absorption spectra is primarily a small blue-shift and that a secondary effect is that spectroscopic features that correspond to dark excitations for the anhydrous nanostructures gain intensity and new absorption peaks are predicted to appear. The effect of adsorbed water on the localisation of excited states is to produce small shifts in the values of the excited stabilisation energies but, more importantly, it results in the formation of extra minima when compared with the case for anhydrous ZnS. Finally, the effect of water on photoluminescence (PL) energies is predicted to be small but the appearance of extra minima induced by the presence of adsorbed water is expected to lead to a splitting/broadening of the PL signal.     

Hyperelliptic parametrizations of $$\pmb {\mathbb {Q}}$$ Q -curves

The Ramanujan Journal - In this paper, our aim is to find the radii of starlikeness and convexity of the Ramanujan type function for three different kinds of normalization by using their...     

Improved thermosets obtained from cycloaliphatic epoxy resins and γ‐butyrolactone with lanthanide triflates as initiators. I. Study of curing by differential scanning calorimetry and Fourier transform infrared

3,4‐Epoxycyclohexylmethyl 3,4‐epoxycyclohexane carboxylate was cured with different proportions of γ‐butyrolactone with lanthanum, samarium, and ytterbium triflates as catalysts. The curing was studied with differential scanning calorimetry (DSC) and Fourier transform infrared in the attenuated‐total‐reflection mode (FTIR/ATR). FTIR/ATR was used to monitor the competitive reactive processes and to quantify the evolution of the epoxide, lactone, and intermediate spiroorthoester groups. The glass‐transition temperature of the crosslinked materials was high and increased when the proportion of lactone decreased. The kinetics were studied with DSC experiments and were analyzed with isoconversional procedures. The differences in the reactivities of the systems were related to the Lewis acidity of the lanthanide salt used as the initiator. An increase in the proportion of lactone produced an increase in the reaction rate. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2337‐2347, 2005