Synthesis and immobilization of molecular switches onto titaniumdioxide nanowires

The precursor [Fe^III(L)Cl (L = N,N′-bis(2′-hydroxy-3′-methyl-benzyliden)-1,7-diamino-4-azaheptane) is combined with [Mo(CN)₈]^4? yields a star shaped nona-nuclear cluster, [Mo^IV{(CN)Fe^III(L)}₈]Cl₄. This Fe₈Mo molecule is a high-spin system at room temperature. On cooling to 20 K some of the iron(III) centres in the molybdenum(IV)-star switch to the low-spin state as proven by Mössbauer spectroscopy. This molecule was deposited on TiO₂ nanowires by electrostatic interactions between the cluster cations and the surface functionalized titanium oxide nanowire. The synthesis and surface binding of the multistable molecular switch was demonstrated using IR and UV–Vis spectroscopy (high-resolution) transmission electron microscopy ((HR)TEM) and Mössbauer spectroscopy. High- and low-temperature Mössbauer spectra indicate that the spin state transition of the free cluster molecules is preserved after surface binding. The above results emphasize the possibility of fabricating molecule-based low-dimensional structures by using traditional bottom-up approaches based on the electrostatic interaction between the cluster cations and polymer functionalized nanowires. These results can be generalized for the application to both charged and non-charged molecules.     

M(N3)2(L)]n: building 3-D MII-azido networks with new topologies

Novel 3D topologies combining diazine and azido bridges between MnII magnetic centres have been obtained and characterised by low-temperature magnetic measurements.     

Relativity restored: Dirac anisotropy in QED3

We show that, at long length scales and low energies and to leading order in 1/N expansion, the anisotropic QED in 2+1 dimensions renormalizes to an isotropic limit. Consequently, the (Euclidean) relativistic invariance of the theory is spontaneously restored at the isotropic critical point.     

Boson Stars: Rotation, Formation, and Evolution

Boson stars are descendants of the so-calledgeons of Wheeler, except that they are built from scalarparticles instead of electromagnetic fields. If scalarfields exist in nature, such localized configurations kept together by their self-generatedgravitational field can form within Einstein's generalrelativity. In the case of complex scalar fields, anabsolutely stable branch of such non-topologicalsolitons with conserved particle number exists. Thepresent surge of interest stems from the speculativepossibility that these compact objects could provide aconsiderable fraction of the non-baryonic part of dark matter. In any case, they may serve as aconvenient laboratory for studyingnumerically rapidly rotating bodies in generalrelativity and the generation of gravitational waves.Furthermore, we mention how to detect boson stars by gravitationallensing or gravitational redshift. Finally, we explorethe evolution of boson stars within scalar-tensortheories.     

“Neglect of Diatomic Differential Overlap” in nonempirical quantum chemical orbital theories. II. A polynomial expansion for Δ−1/2 in terms of Legendre and Chebyshev polynomials

Several attempts to justify the Neglect of Diatomic Differential Overlap (NDDO ) approximation in terms of a power series expansion for Δ^?1/2 (Δ is the overlap matrix) have been made (cf. Part I). The new approach for attaining an optimal approximation of Δ^?1/2 represented here transfers the problem of finding an optimal matrix polynomial to an approximation problem of real functions within the spectrum of Δ. Best approximations are derived by use of Legendre and Chebyshev polynomials. © 1995 John Wiley & Sons, Inc.     

Steroide und Sexualhormone. 248. Mitteilung. Die Partialsynthese von 5α-Dihydrohirundigenin und von 5α-dihydroanhydrohirundigenin

A partial synthesis of dihydroanhydrohirundigenin ( 4 ), a hydrogenation product of naturally occurring anhydrohirundigenin ( 2 ) is described. Furthermore 4 is transformed into the formal dihydroderivative 14 of hirundigenin ( 1 ).