Raman spectroscopy of tris-(hydroxymethyl)aminomethane as a model system for the studies of α-chymotrypsin activation by crown ether in organic solvents

Raman spectroscopy is employed to study tris-(hydroxymethyl)aminomethane and its complexes with 18-crown-6. The results obtained are used to interpret the known effect of α-chymotrypsin activation by crown ether in organic solvents. Raman spectra of the samples lyophilized from aqueous solutions at various pH values are measured in solid state, acetonitrile and cyclohexane.     

Frequency dependent conductivity of the interrupted strand model

We present rigorous results on the frequency dependence of the Kubo-Greenwood conductivity of the interrupted-strand — or bond-percolation model, for which exists strong evidence to be relevant for a class of quasi one-dimensional organic conductors and for some mixed valent complex compounds like K₂Pt(CN)₄ Br_0.30 3H₂O. The model describes a linear sequence of one-dimensional metallic boxes or segments separated from each other by perfectly insulating lattice defects. We used both Lotentzian and rectangular averages to obtain the frequency-averaged conductivity as a well-defined physical quantity and found a sharply peaked structure of the conductivity spectrum resulting from the non-zero energy level spacing of one metallic box. Since one has to look very carefully on different frequency average procedures and on the consequences of the energy spectrum of an entire strand one has to precise arguments and results on the low frequency behaviour of the conductivity obtained from numerical considerations recently proposed by P.S. Riseborough.     

The spin statistics connection for dyons

Goldhaber's spin-statistics connection for electric-pole-magnetic-pole composite dyons is deduced in a gauge-invariant way by connecting the spatial interchange operator with a rotation.Supported in part by the National Science Foundation.Supported in part by the National Science Foundation.     

General alloy analogs of itinerant magnetic systems

Magnetically disordered, strong correlated itinerant electron systems are studied within the Hubbard model. Following an alloy analogy, the approximated system hamiltonian contains local vectoral magnetic fields at the atomic sites, which can be oriented into all space directions. The statistical system of the localized magnetic moments (due to the fields) is treated by the aid of a generalized CPA-technique. Supposing a macroscopic magnetic structure of sublattice antiferromagnetism, the formation of incomplete antiferromagnetic ordering of the localized moments is examined. The results show, that the electron density plays an essential roll for the question, whether or not it is possible to go beyond the pure (itinerant) antiferromagnetic state. Including the results of earlier papers for homogeneous macroscopic magnetic structure, on the whole scale of electron densities it is summed up (at zero temperature), where the different states (without-, with incomplete- or with complete magnetic order) are able to exist. It is shown, for fixed density respectively, which different phases are passed through on changing the coupling constant.Work supported by the Deutsche Forschungsgemeinschaft     

Synthesis of pyrrolidine-substituted benzamides via iodocyclization of β-enaminoesters

Novel 2-, and N-substituted 5-methylene-pyrrolidine benzamides and 2-, 3-, and N-substituted 5-methylene-2-pyrroline benzamides were synthesized for the first time in a straightforward manner and in good yields via iodocyclization of γ- and α-alkenyl-β-enaminoesters, respectively. The key step in the process is the synthesis of the methylene-pyrrolidine iodide and methylene-2-pyrroline iodide intermediates. Functional group inter-conversion of these iodides to their amino analogs, and their subsequent coupling to benzoic acids via EDC, afforded the above pyrrolidine/2-pyrroline-substituted benzamides in yields of around 75%.