Discrete Complexes Immobilized onto Click-SBA-15 Silica: Controllable Loadings and the Impact of Surface Coverage on Catalysis

Azidopropyl functionalized mesoporous silica SBA-15 were prepared with variable azide loadings of 0.03–0.7 mmol g^–1 (∼2–50% of maximal surface coverage) through a direct synthesis, co-condensation approach. These materials are functionalized selectively with ethynylated organic moieties through a copper-catalyzed azide alkyne cycloaddition (CuAAC) or “click” reaction. Specific loading within a material can be regulated by either the azide loading or limiting the alkyne reagent relative to the azide loading. The immobilization of ferrocene, pyrene, tris­(pyridylmethyl)­amine (TPA), and iron porphyrin (FeTPP) demonstrates the robust nature and reproducibility of this two-step synthetic attachment strategy. Loading-sensitive pyrene fluorescence correlates with a theoretically random surface distribution, rather than a uniform one; site-isolation of tethered moieties ∼15 Å in length occurs at loadings less than 0.02 mmol g^–1. The effect of surface loading on reactivity is observed in the oxygenation of SBA-15-[Cu^I(TPA)]. SBA-15-[Mn^II(TPA)]-catalyzed epoxidation exhibits a systematic dependence on surface loading. A comparison of homogeneous, site-isolated and site-dense complexes provides insight into catalyst speciation and ligand activity

Comparison of performance of BioPPSy with literature methods for predicting the logarithm of aqueous solubility.

<p>Comparison of performance of BioPPSy with literature methods for predicting the logarithm of aqueous solubility.</p

Snapshot of the BioPPSy software.

<p>Snapshot of the BioPPSy software.</p

Comparison of performance of BioPPSy with literature methods for predicting the logarithm of Caco-2 cell permeability.

<p>Comparison of performance of BioPPSy with literature methods for predicting the logarithm of Caco-2 cell permeability.</p

Comparison of performance of BioPPSy with literature methods for predicting the logarithm of blood-brain barrier permeability.

<p>Comparison of performance of BioPPSy with literature methods for predicting the logarithm of blood-brain barrier permeability.</p

Two-dimensional Covalent Organic Framework Thin Films Grown in Flow

Two-dimensional covalent organic frameworks (2D COFs) are crystalline polymer networks whose modular 2D structures and permanent porosity motivate efforts to integrate them into sensing, energy storage, and optoelectronic devices. These applications require forming the material as a thin film instead of a microcrystalline powder, which has been achieved previously by including a substrate in the reaction mixture. This approach suffers from two key drawbacks: COF precipitates form concurrently and contaminate the film, and variable monomer and oligomer concentrations during the polymerization provide poor control over film thickness. Here we address these challenges by growing 2D COF thin films under continuous flow conditions. Initially homogeneous monomer solutions polymerize while pumped through heated tubing for a given residence time, after which they pass over a substrate. When the residence time and conditions are chosen judiciously, 2D COF powders form downstream of the substrate, and the chemical composition of the solution at the substrate remains constant. COF films grown in flow exhibit constant rates of mass deposition, enabling thickness control as well as access to thicker films than are available from previous static growth procedures. Notably, the crystallinity of COF films is observed only at longer residence times, suggesting that oligomeric and polymeric species play an important role in forming the 2D COF lattice. This approach, which we demonstrate for four different frameworks, is both a simple and powerful method to control the formation of COF thin films

Discrete, Hexagonal Boronate Ester-Linked Macrocycles Related to Two-Dimensional Covalent Organic Frameworks

Discrete, Hexagonal Boronate Ester-Linked Macrocycles Related to Two-Dimensional Covalent Organic Framework

Cotton Fabric Functionalized with a β‑Cyclodextrin Polymer Captures Organic Pollutants from Contaminated Air and Water

Cotton fabric is covalently functionalized with a porous β-cyclodextrin polymer by including the fabric in the polymerization mixture. The resulting functionalized fabric (CD-TFP@cotton) sequesters organic micropollutants, such as bisphenol A, from water with outstanding speed and a capacity 10-fold higher than that of untreated cotton. The functionalized fabric also readily captures volatile organic compounds (VOCs) from the vapor phase more quickly and with a capacity higher than that of untreated cotton as well as three commercially available fabric-based adsorbents. Volatile adsorbed pollutants were fully extracted from CD-TFP@cotton under reduced pressure at room temperature, permitting simple reuse. These properties make cotton functionalized with the cyclodextrin polymer of interest for water purification membranes, odor controlling fabrics, and respirators that control exposure to VOCs. This functionalization approach is scalable, likely to be amenable to other fibrous substrates, and compatible with existing fiber manufacturing techniques

<i>SIRT3</i> from chromosomal to base pair level demonstrating the location and characteristics of the two <i>SIRT3</i> SNPs significantly associated with adjusted mean age at death.

<p>A. <i>SIRT3</i> is located on chromosome 11p15.5, 21332 bp in length with 5 exons.<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115616#pone.0115616-Kent1" target="_blank">[30]</a> Of 12 <i>SIRT3</i> SNPs genotyped, two were significantly associated with age at death, rs511744 and rs4758633, denoted by the blue arrows. These two SNPs are approximately 450 base pairs apart, located just after exon 1. Even though very close in physical location, there was a significant gender × rs4758633 interaction effect (p = 0.08) but not rs511744 (p = 0.49). These two SNPs are not in mammalian conserved regions (MCR) indicating they are likely not causal but in LD with the functional variant. SNPs denoted by a red dash are missense variants; a green dash denotes a synonymous variant. B. Adjusted mean age at death for males and females for rs511744. Data were calculated by multivariable linear regression with adjustment for BMI, smoking, alcohol consumption and comorbidities. Genotype frequency distribution did not differ between males and females for rs511744 (p = 0.86) C. Adjusted mean age at death for males and females for rs4758633. Genotype frequency distribution did differ for rs4758633 (p<0.01).D. rs511744 and rs4758633 are in moderate LD (r² value between 0.5-0.8) for both males and females.</p

Diverse Reactions of PhI(OTf)₂ with Common 2‑Electron Ligands: Complex Formation, Oxidation, and Oxidative Coupling

The crystal structures of bis-pyridine stabilized iodine dications [PhI­(pyr)₂]²⁺ are reported as triflate salts, representing the first ligand supported iodine dications to be structurally characterized. The pyridine complexes are susceptible to ligand exchange in reaction with stronger N-based donors such as 4-dimethylaminopyridine. Attempts to extend this reactivity to N-heterocyclic carbene and phosphine ligands, as has been accomplished in the earlier p-block groups, resulted in redox chemistry, with oxidation of the ligands rather than coordination