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A required first-year laboratory course was overhauled into a semester-long biosciences course-based undergraduate research experience (BioCURE) with a goal of enhancing learning and improving retention. Student attributes and outcomes were continually monitored by the University's Institutional Research office over a 5-year period and compared against the pre-BioCURE (traditional Biology lab course). Success in the BioCURE was found to be correlated with a passing grade (ABC) in prerequisite majors' chemistry as opposed to nonmajors' chemistry; concurrent enrollment in either majors' or nonmajors' chemistry was less effective than prerequisite majors' chemistry. This unique metric, of assessing the value of a chemistry course as seen through the success in a subsequent bioscience course, provides the authors with convincing evidence to encourage educators to focus on a rigorous, early academic chemistry foundation as well as emphasize interconnections with other disciplines. Diving deeper, success in a more challenging chemistry course prior to taking a required biology course during biological science students' first two collegiate years correlated with increases in student success in biological sciences degree plans, as evidenced by subsequent increases in retention into the third year and six year graduation rates. Students with ABC grades in any first-year chemistry course had a higher rate of graduating in an initially chosen bioscience discipline, but majors' chemistry benefited at-risk students disproportionately more than high-GPA students showing that early chemistry success is critical for strengthening a diverse STEM workforce.

Carbohydrates are an essential group of molecules to the organic chemistry classroom providing molecular relevance to a common ingredient in chemical biology. While the meticulous elucidation of the carbohydrate structures by Fischer and others is an engaging topic in the lecture, there are few laboratory experiments that can emulate carbohydrate complexity. Advanced and multidimensional NMR (2D NMR) techniques such as correlation spectroscopies (COrrelation SpectroscopY (COSY), [superscript 13]C Distortionless Enhancement by Polarization Transfer (DEPT), and HETeronuclear CORrelation (HETCOR) or Heteronuclear Single Quantum Coherence (HSQC)) have become more routine as they require less time on today's instruments and are taught more often in lecture. A laboratory experiment is described for second-year introductory undergraduate organic chemistry students that involves the transformation of nutraceutical N-acetyl-d-glucosamine to a-chloroglucosamine tetraacetate. After synthesis and simple workup, students collect four different NMR spectra from which they identify each [superscript 1]H signal in the product. Students learn to identify each signal's multiplicity and how multiple NMR experiments are used to characterize a product. Student confidence in NMR characterization was assessed on a small subset through postlab questions and pre- and postsurvey data.

Additions to the popular evaporation rate determination laboratory of alcohol-based hand-rub sanitizers are described here. Significantly, inquiry-driven protocols for formulating hand-rub sanitizers, falling-ball viscometry, and sanitizer efficacy are included. Incorporation of familiar substances ("molecular relevance") enables students to assimilate knowledge and connect to and recognize interrelated disciplines. To stimulate engagement and project ownership, students were given the opportunity to alter sanitizer formulations by varying the amount and molecular weight of the gelling agent. Viscosities were determined using a falling-ball viscometer to integrate physics and fluid dynamics concepts into these experiments. Lastly, to stress microbiological applications and determine the efficacy of their hand sanitizers, students tested the formulated hand sanitizers for qualitative efficacy using agar plating of skin secretions and comparing colonies formed from sanitized versus nonsanitized hands. Chemistry students with diverse interests recognized links across disciplinary boundaries (e.g., increased their awareness of physical properties of hand sanitizers and the relationship of molecular-scale phenomena to these properties). This three-hour laboratory provides an interdisciplinary supplement directly designed for freshman chemistry and engineering chemistry undergraduates and increases integration among biology, chemistry, engineering, and physics.

Glyphosate (N-(phosphonomethyl)glycine) is the most widely used herbicide on earth. A simple assay to quantify glyphosate concentrations in environmental samples was developed as part of an interdisciplinary effort linking introductory laboratory courses in chemistry, biology, and microbiology. In this 3 h laboratory experiment, students used UV-vis spectroscopy to quantify glyphosate in prepared unknowns and supernatants from glyphosate-treated soil samples. Regression analysis indicated that the assay is linear up to 20.0 ppm, making it particularly useful for detection of low levels of glyphosate in environmental samples. The assay can be used to quantify the activity of glyphosate-degrading soil microorganisms by comparing glyphosate levels between autoclaved and nonautoclaved soil slurries.

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) A °, while nitrogen atoms are coordinated by the central zinc cation with bond lengths of 2.207 (3) and 2.211 (3) A. 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. [ABSTRACT FROM AUTHOR]

Polyampholyte hydrogels have shown promise as functional biomaterial platforms with resistance to nonspecific protein adsorption (nonbiofouling). Yet there are few zwitterionic cross-linkers available to complement these materials and to provide an extended charge density throughout the 3D network. The recent development of peptide-based zwitterionic cross-linkers has shown merit. Indeed, the use of functionalizable amino acids permits the synthesis of a series of peptide-based zwitterionic methacrylate and methacrylamide cross-linkers. Methacrylate additions prior to peptide coupling provide an outside-in strategy when using natural l -serine or l -lysine as substrates to produce a series of methacrylate and methacrylamide combinations, expanding the library of peptide-based cross-linkers. Here, we describe the preparation of such dipeptide combinations as Ser-Lys, Lys-Ser, and Lys-Lys in zwitterionic bis(methacrylate/methacrylamide) cross-linkers. To highlight the utility of this method and its potential to increase the distance between zwitterionic components, syntheses of the tripeptide Lys-Gly-Lys dimethacrylamide and Ser-Gly-Ser dimethacrylate are reported. [ABSTRACT FROM AUTHOR]

The structure of the title complex, [Ag(C11H15N3S)2]PF6, has monoclinic (P21/c) symmetry, and the silver atom has a distorted square-planar geometry. The coordination complex crystallized from mixing silver hexa­fluorido­phosphate with a concentrated tetra­hydro­furan solution of N,N-di­ethyl­phenyl­azo­thio­formamide [ATF; systematic name: 3,3-diethyl-1-(phenyl­imino)­thio­urea] under ambient conditions. The resultant coordination complex exhibits a 2:1 ligand-to-metal ratio, with the silver(I) atom having a fourfold AgN2S2 coordination sphere, with a single PF6 counter-ion. In the crystal, however, one sulfur atom from an ATF ligand of a neighboring complex coordinates to the silver atom, with a bond distance of 2.9884 (14) Å. This creates a polymeric zigzag chain propagating along the c-axis direction. The chains are linked by C—H···F hydrogen bonds, forming slabs parallel to the ac plane. [ABSTRACT FROM AUTHOR]

Redox-active ligands lead to ambiguity in often clearly defined oxidation states of both the metal center and the ligand. The arylazothioformamide (ATF) ligand class represents a redox-active ligand with three possible redox states (neutral, singly reduced, and doubly reduced). ATF--metal interactions result in strong colorimetric transitions allowing for the use of ATFs in metal detection and/or separations. While previous reports have discussed dissolution of zerovalent metals, the resulting oxidation states of coordination complexes have proved difficult to interpret through X-ray crystallographic analysis alone. This report describes the X-ray crystallographic analysis combined with computational modeling of the ATF ligand and metal complexes to deconvolute the metal and ligand oxidation state of ATF--metal complexes. Metal(ATF)2 complexes that originated from zerovalent metals were found to exist as dicationic metal centers containing two singly reduced ATF ligands. When employing CuI salts instead of Cu0 to generate ATF--copper complexes, the CuI in the resulting complexes remained in its oxidation state, and the ATF ligand remained "innocent", existing in its neutral state. Although the use of CuX (X = Br or I) or [Cu(NCMe)4]Y (Y = BF4 or PF6) generated species of the type: [(ATF)Cu(μ-X)]2 and [Cu(ATF)2]Y, respectively, the ATF ligand remained in its neutral state for each species type. [ABSTRACT FROM AUTHOR]

With the growing demand for measurements of organophosphate (OP) pesticide use in agriculture along with the potential threat of OP-based chemical warfare agents, there is a need for new devices or surfaces that can quickly degrade OPs into less toxic substances in a variety of environments. Using surface-initiated atom transfer radical polymerization and post-polymerization synthesis, we prepared a series of quaternary ammonium fluoride-based polymer brushes designed to absorb and degrade OPs. Specifically, a polymer brush was formed using 2-dimethylamino-ethyl methacrylate (DMAEMA) as monomer, which, following post-polymerization quaternization of the tertiary amine with alkylating agents and fluoride ion exchange, afforded the OP-reactive polymer surfaces. Poly(DMAEMA) brushes were grown to thicknesses of ~100 nm on silicon wafers and glass slides and characterized by ellipsometry, atomic force microscopy, and Raman spectroscopy. Quaternization and subsequent ion exchange of the brushes were characterized by Raman spectroscopy and X-ray photoelectron spectroscopy, respectively. The interaction of the brushes with OPs was evaluated using the OP-based pesticide coumaphos, through the presence of the highly fluorescent degradation product chlorferon; analyzed qualitatively via fluorescence microscopy; and confirmed via nuclear magnetic resonance and mass spectrometry. We found that the fluoride form of the brush reliably degraded coumaphos deposited via controlled solution-based applications and aerosol applications (electrohydrodynamic jetting) and from microcontact printing of the dried solid directly onto the brush. No degradation was seen for coumaphos deposited on poly(DMAEMA) or the iodide form of the quaternized brush. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We report a general diffusion basedmethod to form micrometer-scalelateral chemical gradients in polymer brushes via selective alkylation.A quaternized brush gradient is derived from a concentration gradientof alkylating agent formed by diffusion in permeable media arounda microchannel carrying the alkylating agent. Polymer brushes containingboth charge and aromatic gradients are formed using the alkylatingagents, methyl iodide and benzyl bromide, respectively. The gradientsare quantitatively characterized by confocal Raman spectroscopy andqualitatively by fluorescence microscopy. The length and gradientstrength can be controlled by varying the diffusion time, concentrations,and solvents of the alkylating agent solutions. This microfluidicbrush gradient generation method enables formation of 2-D chemicalpotential gradients with a diversity of shapes. [ABSTRACT FROM AUTHOR]

Finding new sources of biologically active compounds for anticancer or antimicrobial therapies remains an active area of research. Azothioformamides (ATFs) with a 1,3 N=N-C=S heterodiene backbone are a new class of biologically active compounds that chelate metals (e.g., Cu) forming stable ATF metal coordination complexes. In this study, ATF ligands were prepared with pyrrolidine, piperidine, N -methylpiperazine, and morpholine substituents on the formamide as to add more heterocyclic drug-like character for biological studies. Formamide derivatives were then complexed with various Cu(I) salts to form coordination complexes. Cu(I) salts were selected as to create potential bioactive compounds with less toxicity. Binding association constants of each Cu(I) salt to ATF ligands were extrapolated from UV-vis titration studies and were corroborated with DFT calculations using a hybrid functional B3LYP method. It was observed that the smaller pyrrolidine functionalized ATFs bound to the Cu(I) salts had stronger binding than any of the larger six-membered-ring heterocycles with association values in the 10 4 - 10 5 M -1 range. The ATF-Cu(I) salt coordination complexes were then evaluated for antimicrobial activity against two bacteria ( Staphylococcus aureus , Escherichia coli ), one yeast ( Candida albicans ), four human cancer lines (A-549, K-562, HT-1080, MDA-MB-231), and two normal human lines (MRC-5, HFF). The ATF ligands themselves were inactive against all microbes and most human lines except K-562 cells, which were sensitive to three of the four ligands (IC 50 's = 7.0-25.5 μM). Most ATF-Cu(I) complexes showed low to medium micromolar activity against Candida albicans (IC 50 's 2.6-24.8 μM) and Staphylococcus aureus (IC 50 's = 3.4-37.7 μM), with increasing activity corresponding to complexes with higher binding association constants. The antiproliferative properties of ATF-Cu(I) metal salt complexes against mammalian cells were mixed, with low to medium micromolar activity across all cell lines. Notably, several ATF-Cu(I) salt coordination complexes showed submicromolar activity against the HT-1080 fibrosarcoma line (0.52-0.69 μM). The results demonstrate promising activity of ATF-Cu(I) complexes, particularly with pyrrolidine as the formamide component. These studies suggest that the stronger binding association values correlate to higher levels of biological activity., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The structure of the title complex, [Ag(C 11 H 15 N 3 S) 2 ]PF 6 , has monoclinic ( P 2 1 / c ) symmetry, and the silver atom has a distorted square-planar geometry. The coordination complex crystallized from mixing silver hexa-fluorido-phosphate with a concentrated tetra-hydro-furan solution of N , N -di-ethyl-phenyl-azo-thio-formamide [ATF; systematic name: 3,3-diethyl-1-(phenyl-imino)-thio-urea] under ambient conditions. The resultant coordination complex exhibits a 2:1 ligand-to-metal ratio, with the silver(I) atom having a fourfold AgN 2 S 2 coordination sphere, with a single PF 6 counter-ion. In the crystal, however, one sulfur atom from an ATF ligand of a neighboring complex coordinates to the silver atom, with a bond distance of 2.9884 (14) Å. This creates a polymeric zigzag chain propagating along the c -axis direction. The chains are linked by C-H⋯F hydrogen bonds, forming slabs parallel to the ac plane.

The coupling of pentenylcarbene complexes and 2-alkynylbenzoyl derivatives affords naphthocycloheptanones in a single step involving simultaneous construction of both the seven-membered ring and one of the aromatic rings. Aryl tethered systems undergo intramolecular cyclopropanation.