Novel extended tetrathiafulvalenes based on acetylenic spacers: synthesis and electronic properties

A selection of mono- and diacetylenic dithiafulvalenes was synthesized and employed for the construction of extended tetrathiafulvalenes (TTFs) with hexa-2,4-diyne-1,6-diylidene or deca-2,4,6,8-tetrayne-1,10-diylidene spacers between the two 1,3-dithiole rings. By stepwise acetylenic scaffolding using (E)-1,2-diethynylethene (DEE) building blocks, an extended TTF containing a total of 18 C(sp) and C(sp(2)) atoms in the spacer was prepared. The versatility of the acetylenic dithiafulvene modules was also established by the efficient synthesis of a thiophene-spaced TTF, employing a palladium-catalyzed cross-coupling reaction. The developed synthetic protocols allow functionalization of the extended TTFs in three general ways: with 1) peripheral substituents on the fulvalene cores, 2) alkynyl moieties laterally appended to the spacer, and 3) cobalt clusters involving acetylenic moieties. Strong chromophoric properties of the extended TTFs were revealed by linear and nonlinear optical spectroscopies. Extensive electrochemical studies and calculations on these compounds are also reported, as well as X-ray crystallographic analyses.     

High-performance liquid chromatography on dynamically modified silica : II. Modification of various silica packings with cetyltrimethylammonium bromide

High-performance liquid chromatography on silica using eluents containing cetyltrimethylammonium (CTMA) bromide was investigated, and adsorption isotherms were determined for two silica packings of different pore diameter and surface area. It was found that about one CTMA ion was adsorbed per square nanometer of the silica surface at pH 7.5 and at a concentration of 6 mM CTMA bromide in 50% of methanol.Fourteen different silica packings were compared using a test mixture, and thirteen were found to exhibit the same selectivity towards the test mixture, which included acids, bases and non-ionic compounds, thus providing a chromatographic system that is largely independent of the origin of the column material.The retention mechanisms for the five test compounds are discussed.     

Solvated positron chemistry. The reaction of hydrated positrons with chloride ions

The reaction of hydrated positrons (c_aq⁺ with cloride ions in aqueous solutions has been studied by means of positron annihilation angular correlation measurements. A rate constant of k = (2.5 ± 0.5) × 10¹⁰ M^?1 s^?1 was found. Probably the reacting positrons annihilated from an e⁺ Cl^? bound state resulting in an angular correlation curve 8% narrower than for the hydrated positron. Carbontetrachloride in benzene seems to give similar, but smaller effect.     

Jacobi functions: The addition formula and the positivity of the dual convolution structure

We prove an addition formula for Jacobi functions analogous to the known addition formula for Jacobi polynomials. We exploit the positivity of the coefficients in the addition formula by giving the following application. We prove that the product of two Jacobi functions of the same argument has a nonnegative Fourier-Jacobi transform. This implies that the convolution structure associated to the inverse Fourier-Jacobi transform is positive. The first author was partially supported by the Danish Natural Science Research Council.     

Perylenediimide--metal ion dyads for photo-induced electron transfer

A novel perylene diimide incorporating a tetradentate ligand was synthesized and the photophysical properties of its Cu(+), Cu(2+), and Fe(3+) complexes were investigated by fluorescence experiments.     

Cuspidal discrete series for semisimple symmetric spaces

We propose a notion of cusp forms on semisimple symmetric spaces. We then study the real hyperbolic spaces in detail, and show that there exists both cuspidal and non-cuspidal discrete series. In particular, we show that all the spherical discrete series are non-cuspidal.     

Household consumption, investment and life insurance

This paper develops a continuous-time Markov model for utility optimization of households. The household optimizes expected future utility from consumption by controlling consumption, investments and purchase of life insurance for each person in the household. The optimal controls are investigated in the special case of a two-person household, and we present graphics illustrating how differences between the two persons affect the controls.     

Magnetic structure of Ni(DCOO)2(D2O)2

Ni(HCOO)(2)(H(2)O)(2) is a structurally simple coordination polymer showing interesting magnetic phase transitions at low temperature (<16K). Previously published studies of these phase transitions have yielded inconsistent results, questioning the correctness of the published magnetic structure. Here heat capacity and magnetic susceptibility of a fully, a partly and a non-deuterated sample were measured, and they all exhibit magnetic phase transitions around 3 and 15 K. Neutron powder diffraction data was collected on the fully deuterated sample at various temperatures between 1.5 and 25 K. A magnetic model was refined against the neutron diffraction data using a spin system composed of two canted antiferromagnetic sublattices. The magnetic moments of the two sublattices show different magnitude, 1.7 μ(B) and 1.3 μ(B), and the temperature dependence of the magnetic sublattices is quite different. One of the sublattices shows the expected temperature behavior of an antiferromagnetic compound whereas the other sublattice follows a Brillouin like function with a slowly increasing magnetization below the Ne?el temperature.