A Free, Tricoordinate Stannylium Cation

Tris(2,4,6-triisopropylphenyl)stannylium tetrakis(pentafluorophenyl)borate constitutes a free, tricoordinate tin cation according to its X-ray structure. There is no coordination between the cation and either solvent or anion, and there are no atoms at apical positions. DFT calculations confirm the structure and indicate that there is no agostic bonding between the ortho isopropyl methinyl hydrogens and the Sn atom. Calculation of the 119Sn chemical shift is in good agreement with the observed value

A Free, Tricoordinate Stannylium Cation

Tris(2,4,6-triisopropylphenyl)stannylium tetrakis(pentafluorophenyl)borate constitutes a free, tricoordinate tin cation according to its X-ray structure. There is no coordination between the cation and either solvent or anion, and there are no atoms at apical positions. DFT calculations confirm the structure and indicate that there is no agostic bonding between the ortho isopropyl methinyl hydrogens and the Sn atom. Calculation of the 119Sn chemical shift is in good agreement with the observed value

A Free, Tricoordinate Stannylium Cation

Tris(2,4,6-triisopropylphenyl)stannylium tetrakis(pentafluorophenyl)borate constitutes a free, tricoordinate tin cation according to its X-ray structure. There is no coordination between the cation and either solvent or anion, and there are no atoms at apical positions. DFT calculations confirm the structure and indicate that there is no agostic bonding between the ortho isopropyl methinyl hydrogens and the Sn atom. Calculation of the 119Sn chemical shift is in good agreement with the observed value

A Free, Tricoordinate Stannylium Cation

Tris(2,4,6-triisopropylphenyl)stannylium tetrakis(pentafluorophenyl)borate constitutes a free, tricoordinate tin cation according to its X-ray structure. There is no coordination between the cation and either solvent or anion, and there are no atoms at apical positions. DFT calculations confirm the structure and indicate that there is no agostic bonding between the ortho isopropyl methinyl hydrogens and the Sn atom. Calculation of the 119Sn chemical shift is in good agreement with the observed value

Comparison of concentration of SOC in desert steppe between 2004 and 2010.

†<p>from Wang (2009).</p>‡<p>Figures in parentheses indicate the percent change between the 2004 and 2010 sampling dates.</p

Biomimetic Anchor for Surface-Initiated Polymerization from Metal Substrates

In this paper, we demonstrate the first use of a catecholic initiator for surface-initiated polymerization (SIP) from metal surfaces to create antifouling polymer coatings. A new bifunctional initiator inspired by mussel adhesive proteins was synthesized, which strongly adsorbs to Ti and 316L stainless steel (SS) substrates, providing an anchor for surface immobilization of grafted polymers. Surface-initiated atom transfer radical polymerization (SI-ATRP) was performed through the adsorbed biomimetic initiator to polymerize methyl methacrylate macromonomers with oligo(ethylene glycol) (OEG) side chains. X-ray photoelectron spectroscopy, surface FT-IR, and contact angle analysis confirmed the sequential grafting of initiator and polymer, and ellipsometry indicated the formation of polymer coatings of up to 100 nm thickness. Cell adhesion experiments performed with 3T3-Swiss albino fibroblasts showed substantially reduced cell adhesion onto polymer grafted Ti and 316L SS substrates as compared to the unmodified metals. Moreover, micropatterning of grafted polymer coatings on Ti surfaces was demonstrated by combining SI-ATRP and molecular assembly patterning by lift-off (MAPL), creating cell-adhesive and cell-resistant regions for potential use as cell arrays. Due to the ability of catechols to bind to a large variety of inorganic surfaces, this biomimetic anchoring strategy is expected to be a highly versatile tool for polymer thin film surface modification for biomedical and other applications

Partial ANOVA table showing degrees of freedom (DF) and <i>P</i>-values from GLM analysis (at α = 0.05) of TN, SOC, MBC and C∶N ratio in the study sites across grazing intensity (GI) and depths (D).

<p>NS not significant.</p

Correlation between SOC, TN, MBC, and C/N for study sites (incorporating all depths and all stocking rates, n = 240 in desert steppe, n = 160 in typical steppe).

**<p>means significant difference at the <i>P</i>≤0.001 level;</p>*<p>means significant difference at the <i>P</i>≤0.05 level;</p>†<p>All values are Pearson correlation coefficient (range 0–1).</p

Concentration and mass of soil organic carbon (SOC) and total nitrogen (TN) for soils from ungrazed (UG), lightly grazed (LG), moderately grazed (MG), and heavily grazed (HG) sites sampled in 2010 in the Desert and Typical steppe, Inner Mongolia.

<p>Different small letters indicate significant differences between different stocking rates (<i>P</i><0.05).</p

Mean monthly air temperature and rainfall distribution for typical steppe and desert steppe in 2010.

<p>Variation of annual average temperature and annual average precipitation from 1990–2010 in typical steppe and desert steppe.</p