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Université de Fribourg

On the coordination behaviour of NO₃⁻ in coordination compounds with Ag⁺Part 1. Solubility effect on the formation of coordination polymer networks between AgNO₃ and L(L= ethanediyl bis(isonicotinate) as a function of solvent

Robin, Adeline Y. ; Sagué, Jorge L. ; Fromm, Katharina M.

In: CrystEngComm, 2006, vol. 8, p. 403-416

The influence of the solubility of AgNO₃ in three solvent systems is studied for the reaction between AgNO₃ and the ligand L(= ethanediyl bis(isonicotinate)). Three solid state structures are obtained, differing in the relative ratio Ag : L in the first case, and in polymorphism in the second. The Ag–O(NO₃⁻) distance correlates strongly with the solubility of AgNO₃ in...

Université de Fribourg

Silver coordination compounds as light-stable, nano-structured and anti-bacterial coatings for dental implant and restorative materials

Slenters, Tünde Vig ; Hauser-Gerspach, Irmgard ; Daniels, Alma U. ; Fromm, Katharina M.

In: Journal of Materials Chemistry, 2008, vol. 18, p. 5359-5362

Silver coordination polymer chains were deposited on Au(111) as a model surface, as well as on gold alloy and titanium as dental implant and restorative materials. The topography of the surface was analysed on the model substrate and it was found to be a nano-structured crystalline material. In vitro investigations in a flow chamber imitating the oral environment prove the anti-bacterial...

Université de Fribourg

Counterion effect on the formation of coordination polymer networks between AgNO₃ and L (2,2′-oxybis(ethane-2,1-diyl) diisonicotinate) Part 2

Sague, Jorge L. ; Meuwly, Markus ; Fromm, Katharina M.

In: CrystEngComm, 2008, vol. 10, p. 1542-1549

Herein we report the synthesis and characterization by single crystal X-ray diffraction of three new silver(I) complexes {[Ag₂·L₂](NO₃)₂(H₂O)₄} (1), {[Ag₂·L₂](NO₃)₂} (2) and {[Ag₂·L₂](NO₃)₂} (3). Whereas compounds 2 and 3 are...

Université de Fribourg

Amino acids in iron oxide mineralization: (incomplete) crystal phase selection is achieved even with single amino acids

Mantion, Alexandre ; Gozzo, Fabia ; Schmitt, Bernd ; Stern, Willem B. ; Gerber, Yvonne ; Robin, Adeline Y. ; Fromm, Katharina M. ; Painsi, Monika ; Taubert, Andreas

In: The Journal of Physical Chemistry C, 2008, vol. 112, no. 32, p. 12104–12110

Iron oxides are important minerals in biology and materials science. Using biomimetic synthesis, a variety of iron oxides have been fabricated. However, it is still not clear how growth modifiers like amino acids and peptides select different crystal phases of a complex material like iron oxide. The current paper shows that already with single amino acids, (incomplete) crystal phase selection is...

Université de Fribourg

Antimicrobial coatings for implant surfaces

Brunetto, Priscilla S. ; Fromm, Katharina M.

In: Chimia, 2008, vol. 62, no. 4, p. 249-252

Body-foreign materials are used more and more frequently in our lives: joint implants (hips, knees, fingers, etc.), catheters, pacemakers, dental and aesthetic implants, etc. The increasing numbers of patients requiring such implants also raises the absolute numbers of implant-related infections. Thus, it is known that body-foreign materials are prone to bacterial adhesion and subsequent biofilm...

Université de Fribourg

Coordination polymer networks with s-block metal ions

Fromm, Katharina M.

In: Coordination Chemistry Reviews, 2008, vol. 252, no. 8-9, p. 856-885

Université de Fribourg

Silver nanoparticle engineering via oligovaline organogels

Mantion, Alexandre ; Guex, A. Geraldine ; Foelske, Annette ; Mirolo, Laurent ; Fromm, Katharina M. ; Painsi, Monika ; Taubert, Andreas

In: Soft Matter, 2008, vol. 4, no. 3, p. 606-617

L-Valine-based oligopeptides with the chemical structure Z–(L-Val)₃–OMe and Z–(L-Val)₂–L-Cys(S-Bzl)–OMe form stable organogels in butanol. Both peptides are efficient gelators, but Z–(L-Val)₂–L-Cys(S-Bzl)–OMe crystallizes more readily than Z–(L-Val)₃–OMe. The two peptides can form mixed fibers, which also gel butanol. The resulting organogels are very similar to...

Université de Fribourg

Analogy of the Coordination Chemistry of Alkaline Earth Metal and Lanthanide Ln²⁺ Ions: The Isostructural Zoo of Mixed Metal Cages [IM(OtBu)₄{Li(thf)}₄(OH)] (M=Ca, Sr, Ba, Eu), [MM′₆(OPh)₈(thf)₆] (M=Ca, Sr, Ba, Sm, Eu, M′=Li, Na), and their Derivatives with 1,2-Dimethoxyethane

Maudez, William ; Meuwly, Markus ; Fromm, Katharina M.

In: Chemistry - A European Journal, 2007, vol. 13, no. 29, p. 8302 - 8316

As previously shown, alkali and alkaline earth metal iodides in nonaqueous, aprotic solvents behave like transition metal halides, forming cis- and trans-dihalides with various neutral O-donor ligands. These compounds can be used as precursors for the synthesis of new mixed alkali/alkaline earth metal aggregates. We show here that Ln²⁺ ions form isostructural cluster compounds....

Université de Fribourg

Transport properties of solid state crown ether channel systems

Fromm, Katharina M. ; Bergougnant, Rémi D.

In: Solid State Sciences, 2007, vol. 9, no. 7, p. 580-587

Single crystals of [(H₂O)⊂(DB18C6)(μ₂-H₂O)2/2][(H₃O)⊂(DB18C6)(μ₂-H₂O)2/2]I₃ 1 were shown to possess ideally stacked crown ether molecules which form channels running in one direction through the solid state structure. By immersion of single crystals of 1 into NaOH, ion exchange takes place to yield the compound...

Université de Fribourg

From simple rings to one-dimensional channels with calix[8]arenes, water clusters, and alkali metal ions

Bergougnant, Rémi D. ; Robin, Adeline Y. ; Fromm, Katharina M.

In: Tetrahedron, 2007, vol. 63, no. 44, p. 10751-10757

The macrocycle 4-tert-butylcalix[8]arene (L) was reacted with alkali metal carbonates (Li₂CO₃, Na₂CO₃, K₂CO₃, Rb₂CO₃, and Cs₂CO₃) at the interface of a biphasic THF/water system. Needle-like crystals with a general formula [Ax(4-tert-butylcalix[8]arene-xH)(THF)y(H₂O)z] (with A=Li, Na, K, Rb, Cs,...