title: From molecular germanates to microporous Ge@C via twin polymerization.
abstract: Four molecular germanates based on salicyl alcoholates, bis(dimethylammonium) tris[2-(oxidomethyl)phenolate(2-)]germanate (1), bis(dimethylammonium) tris[4-methyl-2-(oxidomethyl)phenolate(2-)]germanate (2), bis(dimethylammonium) tris[4-bromo-2-(oxidomethyl)phenolate(2-)]germanate (3) and dimethylammonium bis[2-tert-butyl-4-methyl-6-(oxidomethyl)phenolate(2-)][2-tert-butyl-4-methyl-6-(hydroxymethyl)phenolate(1-)]germanate (4), were synthesized and characterized including single crystal X-ray diffraction analysis. In the solid state, compounds 1 and 2 exhibit one-dimensional hydrogen bonded networks, whereas compound 4 forms separate ion pairs, which are connected by hydrogen bonds between the dimethylammonium and the germanate moieties. The potential of these compounds for thermally induced twin polymerization (TP) was studied. Germanate 1 was converted by TP to give a hybrid material (HM-1) composed of phenolic resin and germanium dioxide. Subsequent reduction with hydrogen provided a microporous composite containing crystalline germanium and carbon (Ge@C -C-1, germanium content ∼20%). Studies on C-1 as an anode material for Li-ion batteries revealed reversible capacities of ∼370 mA h gGe@C(-1) at a current density up to 1384 mA g(-1) without apparent fading for 500 cycles.
authors.affiliation: Technische Universität Chemnitz, Fakultät für Naturwissenschaften, Institut für Chemie, Professur Koordinationschemie, 09107 Chemnitz, Germany. michael.mehring@chemie.tu-chemitz.de.
authors.forename: Philipp
authors.initials: P
authors.lastname: Kitschke
authors.forename: Marc
authors.initials: M
authors.lastname: Walter
authors.forename: Tobias
authors.initials: T
authors.lastname: Rüffer
authors.forename: Heinrich
authors.initials: H
authors.lastname: Lang
authors.forename: Maksym V
authors.initials: MV
authors.lastname: Kovalenko
authors.forename: Michael
authors.initials: M
authors.lastname: Mehring