No abstract

The heterobimetallic complexes [Mn((i)PrNPPh(2))(3)Cu((i)PrNHPPh(2))] (1) and [Fe((i)PrNPPh(2))(3)Cu((i)PrNHPPh(2))] (2) have been synthesized by the one pot reaction of LiN(i)PrPPh(2), MCl(2) (M = Mn, Fe), and CuI in high yield. Addition of excess CuI into 2 or directly to the reaction mixture led to the formation of a heterotrimetallic [Fe((i)PrNPPh(2))(3)Cu(2)((i)PrNPPh(2))] (3) in good yield. Complexes 1-3 have been characterized by means of elemental analysis, paramagnetic (1)H NMR, UV-vis spectroscopy, cyclic voltammetry, and single crystal X-ray analysis. In all three complexes, Mn or Fe are in the +2 oxidation state and have a high spin electron configuration, as evidenced by solution Evans' method. In addition, the oxidation state of Fe in complex 3 is confirmed by zero-field (57)Fe Mössbauer spectroscopy. X-ray crystallography reveals that the three coordinate Mn/Fe centers in the zwitterionic complexes 1-3 adopt an unusual trigonal planar geometry.

Incorporation of an interpenetrating polymer network into an existing single polymer network enables augmentation of the original substrate’s mechanical properties, and translation of this concept from purely synthetic materials to natural-synthetic hybrid systems provides the opportunity to reinforce mechanical properties of bulk biological substrates. In many disease states, bodily tissues experience a deterioration of mechanical properties which renders them prone to further material failure. Herein, a tissue-supplementing technique is described in which an interpenetrating biomimetic hydrogel is polymerized in situ throughout cartilage tissue. The treatment restores the inferior compressive properties of osteoarthritic cartilage to that of healthy cartilage, preferentially localizing to weaker regions of tissue. Furthermore, the treatment technique preserves cartilage under harsh articulation conditions, showing promise as a materials-based treatment for early-stage osteoarthritis.

The bidentate metalloligand (NMe 2 ) 2 Zr( i PrNPPh 2 ) 2 (1) has been synthesized and treated with (COD)PtMe 2 to generate the heterobimetallic Zr/Pt species (NMe 2 ) 2 Zr( i PrNPPh 2 ) 2 PtMe 2 (2). Complex 2 can be treated with TMSCl to generate the dichloride species Cl 2 Zr( i PrNPPh 2 ) 2 PtMe 2 (3), a useful precursor for generating a range of Zr/Pt complexes featuring different Zr substituents. Upon treatment with lithio or Grignard reagents, Cl(Me 3 SiCH 2 )Zr( i PrNPPh 2 ) 2 PtMe 2 (4), (Me 3 SiCH 2 ) 2 Zr( i PrNPPh 2 ) 2 PtMe 2 (5), and Me 2 Zr( i PrNPPh 2 ) 2 PtMe 2 (6) have been synthesized. Complexes 1-6 have been characterized using X-ray crystallography, revealing an unmistakable trend in Pt-Zr distance as a function of the electron-releasing ability of the Zr-bound X-type ligands. In addition, the solid-state structure of 6 reveals isomerization of the chelating metalloligand from a cis to a trans configuration about Pt and an unusual anagostic interaction between one of the Ptbound Me groups and the electron-deficient Zr center. This isomerization is accompanied by a thermoneutral methyl group exchange process between Zr and Pt.