How Pure is Pure? Metal Complexation Studies Directed Towards Pharmaceutical Drug Purification

Catalytic processes play critical roles in the modern-day industrial syntheses of many commonplace materials such as plastics, fuel production, electronics, and pharmaceuticals. Transition metal catalysts may become homogeneously embedded within solid nanomaterials during their synthetic scheme, which can result in deleterious effects on both the construction and durability of the material as well as its intended functionality. Traditional purification methods of these materials rely upon harsh reaction conditions that may either affect or allow for specific functionalities. Arylazothioformamide (ATF) ligands have proven to be a mild alternative for their ability to chelate these solid transition metal catalysts. This work will describe the synthetic steps towards developing a versatile library of ATF ligands, the characterization of those already synthesized, and initial chelation studies directed towards the purification of pharmaceutical drugs which employ catalytic processes in their production

The synthesis and structural properties of a chloridobis{N-[(4-methoxyphenyl)imino]pyrrolidine-1-carboxamide}zinc(II) (acetonitrile)trichloridozincate coordination complex

The title complex, [ZnCl(C12H15N3O2)2][ZnCl3(CH3CN)], was synthesized and its structure was fully characterized through single-crystal X-ray diffraction analysis. The complex crystallizes in the orthorhombic system, space group Pbca (61), with a central zinc atom coordinating one chlorine atom and two pyrrolidinyl-4-methoxyphenyl azoformamide ligands in a bidentate manner, utilizing both the nitrogen and oxygen atoms in a 1,3-heterodiene (N=N—C=O) motif for coordinative bonding, yielding an overall positively (+1) charged complex. The complex is accompanied by a [(CH3CN)ZnCl3]− counter-ion. The crystal data show that the harder oxygen atoms in the heterodiene zinc chelate form bonding interactions with distances of 2.002 (3) and 2.012 (3) Å, while nitrogen atoms are coordinated by the central zinc cation with bond lengths of 2.207 (3) and 2.211 (3) Å. To gain further insight into the intermolecular interactions within the crystal, Hirshfeld surface analysis was performed, along with the calculation of two-dimensional fingerprint plots. This analysis revealed that H...H (39.9%), Cl...H/H...Cl (28.2%) and C...H/H...C (7.2%) interactions are dominant. This unique crystal structure sheds light on arrangement and bonding interactions with azoformamide ligands, and their unique qualities over similar semicarbazone and azothioformamide structures

The Use of Thin-Film Polymeric Surfaces to Model Quorum Sensing Capabilities in Bacterial Bioflims

The surface of thin-film polymer brushes is analogous to naturally occurring, ubiquitous, bacterial biofilms. Bacterial biofilms rely heavily on their ability to shuttle hormones through the polymeric surface of bacterial biofilms. This phenomenon is known as quorum sensing which functions to regulate gene expression and allows the biofilm to better adapt to its environment. The intention of this research project is to use synthetic thin-film polymeric surfaces to model such capabilities. The project thus far has primarily utilized the living radical polymerizations of poly(2-hydroxyl ethyl methacrylate) (poly(HEMA)) on silicon wafer surfaces due to its terminal hydroxyl group and high potential for post-polymerization functionalization. The surfaces of the poly(HEMA) brushes have been functionalized with several acyl chloride groups of differing carbon-chain lengths. These surfaces are currently undergoing characterization with the use of Atomic Force Microscopy. The wetting properties of these functionalized surfaces are being determined using contact angle measurements and goniometry. Further characterization will be done utilizing Raman Spectroscopy as well as fluorescent microscopy. This will facilitate our capability to use the thin-film polymeric surfaces to model quorum sensing capabilities in bacterial biofilms

Total Synthesis and Derivation of Humulones and Lupulones as Possible Biologically Active Agents

Humulones and lupulones have affirmed themselves as key ingredients in the multi-billion dollar brewing industry. Originally exploited for their bacteriostatic properties, these compounds also exhibit high levels of biological activity against a variety of diseases. Although quantifiable, the isolation and separation of specific humulones and lupulones has proven difficult, thus establishing efficient synthetic routes will be of value to those desiring exact bittering qualities and to the pharmaceutical community. Our investigations are towards developing a synthetic route to a library of humulones, lupulones, and their derivatives as possible biologically active agents against myriad diseases. The key step in our efficient syntheses of individual humulones is a copper mediated asymmetric oxidative dearomatization involving a chiral ligand. New compounds will be biologically tested through our collaborations. Active agents may lead to a transformation in hops as sources to the next generation of medicines

Key features and updates for Origin 2018

Abstract OriginLab’s newest version update to Origin and OriginPro includes ease-of-use features, like Origin Central updates and creation of an App Center, as well as larger changes like the addition of Unicode characters, alteration to how user files are stored and visually searched, and user input formula in cells within worksheets. These features add additional value to an already powerful data analysis and plotting software package

Synthesis of β‑<i>C</i>‑GlcNAc Ser from β‑<i>C</i>‑Glc Ser

The glycosylation of proteins, specifically installation of <i>O</i>-GlcNAc on Ser/Thr residues, is a dynamic control element for transcription repression, protein degradation, and nutrient sensing. To provide homogeneous and stable structures with this motif, the synthesis of a C-linked mimic, <i>C</i>-GlcNAc Ser, has been prepared from the <i>C</i>-Glc Ser by a double inversion strategy using azide to insert the C-2 nitrogen functionality. The <i>C</i>-Glc Ser was available by a ring-closing metathesis and hydroalkoxylation route

Polymer Brushes Patterned with Micrometer-Scale Chemical Gradients Using Laminar Co-Flow

We present a facile microfluidic method for forming narrow chemical gradients in polymer brushes. Co-flow of an alkylating agent solution and a neat solvent in a microfluidic channel forms a diffusion-driven concentration gradient, and thus a gradient in reaction rate at the interface of the two flows, leading to a quaternization gradient in the underlying poly­(2-(dimethylamino)­ethyl methacrylate) polymer brush. The spatial distribution of the quaternized polymer brush is characterized by confocal Raman microscopy. The quaternization gradient length in the polymer brush can be varied with the injection flow rate and the distance from the co-flow junction. A chemical gradient in the polymer brush as narrow as 5 μm was created by controlling these parameters. The chemical gradient by laminar co-flow is compared with numerical calculations that include only one adjustable parameter: the reaction rate constant of the polymer brush quaternization. The calculated chemical gradient agrees with the experimental data, which validates the numerical procedures established in this study. Flow of multiple laminar streams of reactive agent solutions enables single-run fabrication of brush gradients with more than one chemical property. As one example, four laminar streamsneat solvent/benzyl bromide solution/propargyl bromide solution/neat solventgenerate multistep gradients of aromatic and alkyne groups. Because the alkyne functional group is a click-reaction available site, the alkyne gradient could allow small gradient formation with a wide variety of chemical properties in a polymer brush

General Method for Forming Micrometer-Scale Lateral Chemical Gradients in Polymer Brushes

We report a general diffusion based method to form micrometer-scale lateral chemical gradients in polymer brushes via selective alkylation. A quaternized brush gradient is derived from a concentration gradient of alkylating agent formed by diffusion in permeable media around a microchannel carrying the alkylating agent. Polymer brushes containing both charge and aromatic gradients are formed using the alkylating agents, methyl iodide and benzyl bromide, respectively. The gradients are quantitatively characterized by confocal Raman spectroscopy and qualitatively by fluorescence microscopy. The length and gradient strength can be controlled by varying the diffusion time, concentrations, and solvents of the alkylating agent solutions. This microfluidic brush gradient generation method enables formation of 2-D chemical potential gradients with a diversity of shapes

Proton Diffusion in Hydrogels under Different Solidification Procedures

Trichloroethylene (TCE) continues to be a major carcinogenic pollutant found the superfund sites in the United States. TCE is regulated at parts per billion levels in drinking water by the United States Environmental Protection Agency (EPA). Bioremediation is an important strategy in degrading TCE, but pH control is critical in complete degradation of TCE. In this study, different solidification procedures of polymer hydrogels were evaluated for use in protecting microorganisms degrading TCE by adsorbing and diffusing out acid. Different hydrogel polymers crosslinking agents and cross-linking times were tested to determine the effect on acid diffusivity. A diaphragm cell was used to measure the rate at which acid moves through the hydrogels. We discovered that increasing physical and chemical crosslinking improves structural support of the hydrogels. Acid diffusion rate results were statistically insignificant relative to a 10% PVA cryogel control. However, it was observed that with the addition of ionic substances such that of potassium chloride, effective diffusivity increased approximately 100% for both chemical and physical crosslinking. These results help provide important knowledge in building the structure of the membranes while maintaining high diffusivity rate which contribute to the strategy of bioremediation