We study numerically the binding of one semiflexible charged polymer onto an oppositely charged sphere. Using parameters appropriate for DNA-histone complexes, we find complete wrapping for intermediate salt concentrations only, in agreement with experiments. For high salt concentrations, a strongly discontinuous dewrapping occurs. For low salt concentrations, we find multiple conformational transitions, leading to an extended DNA configuration. The wrapped states are characterized by spontaneously broken rotational and mirror symmetries, giving rise to four distinct structures.

We investigate the complexation behavior between a semiflexible charged polymer and an oppositely charged sphere with parameters appropriate for the DNA-histone system. We determine the ground state of a simple free energy expression (which includes electrostatic interactions on a linear level) numerically and use symmetry arguments to divide the obtained DNA configuration into broad classes, thereby obtaining global phase diagrams. We pay specific attention to the effects of salt concentration, DNA length variation, DNA charge renormalization, and externally applied force on the obtained complex structures.

Complexation between a stiff charged cylinder and an oppositely charged semiflexible polymer is studied using linear Debye-Hückel theory (valid for large enough salt concentration or weakly charged polymers). The salt-concentration-dependent phase diagram features helical and, favored for increasing stiffness of the wrapping polymer, straight wrapping morphologies. Non-linear (counterion release) effects are discussed on the scaling level.

Mixed metal alkoxides containing main group elements with ns z electron configurations of the general formula M (OtBu)3 M' (M = In, TI; M' = Ge, Sn, Pb), M' (OtBu)3 M (OtBu)3 M' (M = divalent metal atom, M'= Ge, Sn) and (OtBu)M'(OtBu)2M(OtBu)2M(OtBu)2M'(OtBu) (M = Co, Ni; M'= Ge, Sn) can be reacted with simple metal carbonyls. The products obtained are composed of a one-dimensional array of metal atoms held together by direct metal-metal bonds or by bridging alkoxide groups. The following compounds have been isolated and characterized by IR and NMR spectroscopy and X-ray diffraction (M'=Ge, Sn, Pb; M=In, T1; MT=transition metal): M'(OtBu)3M-Mr(CO),, (CO),M r-M(OtBu)3 M'-MT(CO),, M'(OtBu)3 M-MT(CO)n M (OtBu)3 M' , (CO)n MT-M' (OtBu)3 M (OtBu)3 M'-Mr(CO)., (CO)n MT-M' [OtBu] (OtBu)2 M (OtBu)2 M(OtBu)2 [OtBu] M'-MT(CO)n and (CO)n M T-M'(OtBu)3 M-MT(CO)n M (OtBu)a M'-MT(CO),~. In addition, an oligomeric species of the general formula [Sn(OtBu)3In-Mo(CO)4].-Sn(OtBu)aIn-Mo(CO)s with n ~ 9, 10 has been isolated.

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