Intermolecular Interactions and Spectroscopic Signatures of the Hydrogen-Bonded System—n-Octanol in Experimental and Theoretical Studies

n-Octanol is the object of experimental and theoretical study of spectroscopic signatures and intermolecular interactions. The FTIR measurements were carried out at 293 K for n-octanol and its deuterated form. Special attention was paid to the vibrational features associated with the O-H stretching and the isotope effect. Density Functional Theory (DFT) in its classical formulations was applied to develop static models describing intermolecular hydrogen bond (HB) and isotope effect in the gas phase and using solvent reaction field reproduced by Polarizable Continuum Model (PCM). The Atoms in Molecules (AIM) theory enabled electronic structure and molecular topology study. The Symmetry-Adapted Perturbation Theory (SAPT) was used for energy decomposition in the dimers of n-octanol. Finally, time-evolution methods, namely classical molecular dynamics (MD) and Car-Parrinello Molecular Dynamics (CPMD) were employed to shed light onto dynamical nature of liquid n-octanol with emphasis put on metric and vibrational features. As a reference, CPMD gas phase results were applied. Nuclear quantum effects were included using Path Integral Molecular Dynamics (PIMD) and a posteriori method by solving vibrational Schrödinger equation. The latter applied procedure allowed to study the deuterium isotope effect.     

Production of 64Cu on the Sherbrooke TR-PET cyclotron

At energies £15 MeV, ⁶⁴Cu is most readily produced using the ⁶⁴Ni(p,n)⁶⁴Cu reaction. Space restrictions in the TR-PET target selector required a target system of compact design that would still allow the quick and easy removal of the irradiated target. The target consists of a ⁶⁴Ni-plated rhodium disc held in place by a threaded cooling assembly. For removal, the cooling block is rotated slightly, allowing the disc to fall into a shielding container. The nickel is dissolved and the ⁶⁴Cu separated by anion exchange or electrochemical deposition. Yields of up to 330 mCi of radiochemically pure ⁶⁴Cu have been obtained.     

Monte-Carlo method for determining the quenching function from variable heating rate measurements

In thermoluminescence (TL) measurements radiative recombination takes place at various temperatures. Typically, the quantum efficiency of luminescence decreases with increasing temperature. We call this mechanism the thermal quenching. There is no simple method to ‘restore’ unquenched TL data. This paper presents an algorithm, based on the Monte-Carlo method, for calculating the quenching function and restoring the unquenched TL curve. For this purpose we use a series of TL glow curves measured at the same initial conditions with variable heating rates. The method is quite general and no particular kinetic model of TL need to be assumed. The reliability of the method is tested using computer generated TL glow curves obeying the simple trap model (STM) kinetics.     

Dose-rate effect in the model of semi-localized transitions (SLT)

The model of semi-localized transitions (SLT) unifies two standard models of thermoluminescence (TL) and optically stimulated luminescence (OSL) kinetics – the simple trap model (STM) and the model of localized transitions (LT). SLT equations were previously formulated for the heating stage of TL. This paper presents SLT equations for the excitation and fast relaxation stages. Exemplary calculations were performed to show the occurrence of dose-rate effect – previously found in STM. It is shown that the dose-rate effect occurs for both – localized and delocalized TL glow peaks.     

Methandiide Complexes (R2CM2) of the Heavier Alkali Metals (M=Potassium,Rubidium, Cesium): Reaching the Limit?

Size does matter : Whereas geminal bimetallic bis(amidophosphorano)methandiide complexes of the heavy alkali metals K and Rb are relatively stable, that of Cs, the largest and most electropositive of the alkali metals, decomposes to form a cyclic product, which cocrystallizes with benzylcesium.

     

Synthesis, structure, and reactivity of a stabilized calcium carbene: R(2)CCa

Attempted 2-fold deprotonation of the bis(iminophosphorano)methane ligand, H(2)C(Ph(2)P=NSiMe(3))(2) (4-H(2)), with a calcium amide led only to mono-deprotonation. The crystal structure of (4-H)(2)Ca shows two tridentate ligands with short Ca-N and a rather long Ca-C bond. Reaction of 4-H(2) with a dibenzylcalcium complex gave the desired 2-fold deprotonation and formation of 4-Ca, which crystallized as a dimeric complex. Analysis of the calculated atomic and group charges in 4-H(2), (4-H)(2)Ca, and [4-Ca](2) showed that the negative charge at the imine nitrogens only slightly increases upon successive deprotonation of 4-H(2). The electron density at the central carbon, however, increases considerably: the charge on the carbene carbon in [4-Ca](2) is ca. -1.8. The negative charge in 4(2)(-) is therefore mainly located on the carbon. Reaction of [4-Ca](2) with benzophenone in benzene gave the remarkably stable adduct [4-Ca](2) x O=CPh(2), which was characterized by X-ray diffraction. Reaction of [4-Ca](2) with adamantylcyanide gave exclusive formation of the adduct [4-Ca](2) x (N identical withCR)(2), which did not react further, even at higher temperatures. Addition of cyclohexyl isocyanate to a benzene solution of [4-Ca](2) gave immediate [2 + 2]-cycloaddition and formation of a dianionic tetradentate ligand that binds to Ca(2+) through two nitrogens, the central carbon, and an oxygen. This product crystallized as a dimer with bridging oxygen atoms.