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Two gas phase deuterium/hydrogen exchange reactions are described utilizing a simple inexpensive glass catalyst tube containing 0.5% Pd on alumina through which gas mixtures can be passed and products collected for analysis. The first of these exchange reactions involves H2 + D2, which proceeds at temperatures as low as 77 K yielding a mixture that includes HD. Products are analyzed by ¹H NMR spectrometry. At low temperatures, this reaction requires a catalyst, but it proceeds without a catalyst at high temperature of a gentle flame. The second deuterium/hydrogen exchange reaction involves CH4 + D2 producing a series of isotopologues, methane-dx, x = 0-4, with product analysis by GC-MS and ¹H NMR spectrometry. This reaction only takes place in the presence of a catalyst at elevated temperatures due to the large energy of activation of the sp³-carbon-to-hydrogen bond. Two outcomes have been observed in the literature regarding D/H exchange and methane. Some catalysts and temperature conditions yield a single-exchange result, methane-d1. Others yield multiple exchange results, such as we observe with our catalyst. The single exchange outcome is associated with lower temperatures. Two mechanisms, one by Kemball (1959) and one by Frennet (1974), have been put forth to explain single and multiple exchange outcomes. We discuss our results in the context of these mechanisms. Interested readers could develop a research experience for undergraduate chemistry students based on the open-ended experiments presented here. [ABSTRACT FROM AUTHOR]

In this laboratory experiment, students determine the number-average molar masses and second virial coefficients of polyethylene glycol (PEG) polymers ranging in molar mass from 200 to 1500 g mol-1 using vapor pressure osmometry (VPO). Students assess VPO in relation to accurate molar mass calculations of PEG polymers. Additionally, students use the second virial coefficients to identify any PEG self-interactions and any dependence of the second virial coefficient on PEG molar mass. This laboratory experiment is suitable for a biophysical or physical chemistry laboratory. [ABSTRACT FROM AUTHOR]

The strongly exothermic nature of reactions between molecular oxygen and all organic molecules as well as many other substances is explained in simple, general terms. The double bond in O2 is much weaker than other double bonds or pairs of single bonds, and therefore the formation of the stronger bonds in CO2 and H2O results in the release of energy, which is given off as heat or increases thermal motion. This explains why fire is hot regardless of fuel composition. The bond energies in the fuel play only a minor role; for example, the total bond energy of CH4 is nearly the same as that of CO2. A careful analysis in terms of bond enthalpies, counting double bonds as two bonds to keep the total number of bonds unchanged, gives the heat of combustion close to -418 kJ/mol (i.e., -100 kcal/mol) for each mole of O2, in good agreement (±3.1%) with data for >500 organic compounds; the heat of condensation of H2O, -44 kJ/mol, is also included in the analysis. For 268 molecules with ≥ 8 carbon atoms, the standard deviation from the predicted value is even smaller, 2.1%. This enables an instant estimate of the heat of combustion simply from the elemental composition of the fuel, even for a complex mixture or unknown molecular structure, and explains principles of biofuels production. The analysis indicates that O2, rather than fuels like octane, H2, ethanol, or glucose, is the crucial "energy-rich" molecule; we briefly explain why O2 is abundant in air despite its high enthalpy. [ABSTRACT FROM AUTHOR]

An integrated laboratory experiment applying concepts and techniques developed in organic chemistry, inorganic chemistry, and instrumental analysis is presented for use by students interested in undergraduate research. The experiment incorporates some advanced laboratory practices such as multistep organic synthesis and purification, detailed reaction mechanism, air-sensitive metalation techniques, variable-temperature NMR experiments, cyclic voltammetry, and single crystal X-ray crystallography. Subsequently, students are presented with an experience that mirrors fundamental inorganic chemistry research practices found in laboratories throughout the world. [ABSTRACT FROM AUTHOR]

Image While X-ray powder diffraction (XRPD) is a fundamental analytical technique used by solid-state laboratories across a breadth of disciplines, it is still underrepresented in most undergraduate curricula. In this work, we incorporate XRPD analysis into an inquiry-based project that requires students to identify the crystalline component(s) of familiar household products. Centering the project on materials which students encounter in their everyday lives helps to demystify the technique, making it accessible to everyone with a basic understanding of crystallinity and unit cells. In an XRPD study, each crystalline component generates a unique set of peaks in the diffractogram. Comparing the collected diffractogram to a library of diffractograms for known crystalline materials allows students to identify the crystalline components in their unknown. Students must determine for themselves the chemical compositions of the possible unknowns, and link their findings back to the analysis of the collected data. Initially challenging, this is the part of the work they respond to most strongly. This lab includes a data collection component, but its inquiry-based objectives can still be achieved by providing the students with simulated diffractograms when the appropriate instrumentation is unavailable. [ABSTRACT FROM AUTHOR]

In this laboratory experiment, students learn how to use ESI to accelerate chemical synthesis and to couple it with on-line mass spectrometry for structural analysis. The Hantzsch synthesis of symmetric 1,4-dihydropyridines is a classic example of a one-pot reaction in which multiple intermediates can serve to indicate the progress of the reaction as a function of the electrospray variable parameters. This reaction allows students to gauge the effects of the spray variables while observing the enhanced reaction rate through product analysis in the charged microdroplets. Soft ionization techniques used in conjunction with collisioninduced dissociation provide students experience with full scan MS to infer reaction progress and collision-induced fragmentation patterns for structural analysis. The experiment as a whole combines the physical phenomena of electrospray, Hantzsch chemical reactivity, and analytical measurements involving use of an ion trap mass spectrometer. [ABSTRACT FROM AUTHOR]

A simple and economical experimental setup is described that enables multiple individuals or groups within a laboratory class to measure the thermal melting of double stranded DNA simultaneously. The setup utilizes a basic spectrophotometer capable of measuring absorbance at 260 nm, UV plastic cuvettes, and a stirring hot plate. Students measure melting curves of short matched and mismatched DNA duplexes, and use quantitative analysis and first derivative curves to determine each duplex's transition melting temperature, Tm. Student data are highly reproducible among groups and from year to year, and give distinct transition melting temperatures for the different duplexes. The protocol could easily be adapted to investigate the effects of other parameters on DNA melting and stability, such as changes in base composition, chain length, and buffer ionic strength. [ABSTRACT FROM AUTHOR]

Three gold-nanoparticle (AuNP) undergraduate experiment modules that are focused on nanoparticles interfacial phenomena have been developed. Modules 1 and 2 explore the synthesis and characterization of AuNPs of different sizes but with the same total gold mass. These experiments enable students to determine how particle size affects the AuNP optical properties and ligand binding capacities. Module 3 investigates the fundamental mechanism governing organothiol self-assembly onto AuNPs and explores the fate of the sulfur-bounded hydrogen (RS-H) for organothiols on the AuNP surface. A benchtop centrifuge, a UV-vis spectrophotometer, and pH strips are needed. The depth of required chemistry knowledge is appropriate for upper-level chemistry students. [ABSTRACT FROM AUTHOR]

Enzyme kinetics is an essential part of a chemistry curriculum, especially for students interested in biomedical research or in health care fields. Though the concept is routinely performed in undergraduate chemistry/biochemistry classrooms using other spectroscopic methods, we provide an optimized approach that uses a real-time monitoring of the kinetics by quantitative NMR (qNMR) spectroscopy and a direct analysis of the time course data using Lambert-W function. The century old Michaelis-Menten equation, one of the fundamental concepts in biochemistry, relates the time derivative of the substrate to two kinetic parameters (the Michaelis constant KM and the maximum rate Vmax) and to the concentration of the substrate. The exact solution to the Michaelis-Menten equation, in terms of the Lambert-W function, is not available in standard curve-fitting tools. The high-quality of the real-time qNMR data on the enzyme kinetics enables a revisit of the concept of applying the progress curve analysis. This is particularly made feasible with the advent of analytical approximations of the Lambert-W function. Thus, the combination of NMR experimental time-course data with progress curve analysis is demonstrated in the case of enzyme (invertase) catalyzed hydrolysis reaction (conversion of sucrose to fructose and glucose) to provide students with direct and simple estimations of kinetic parameters of Michaelis-Menten. Complete details on how to implement the experiment and perform data analysis are provided in the Supporting Information. [ABSTRACT FROM AUTHOR]

In our previous article on CCl4 in this Journal, we presented an investigation of the fine structure of the symmetric stretch of carbon tetrachloride (CCl4) due to isotopic variations of chlorine in C35Clx37Cl4-x. In this paper, we present an investigation of the contributions from both the v = 0 to v = 1 excitation and the v = 1 to v = 2 excitation. We report the calculation of spectral contributions from excited state vibrational transitions (hot bands). All calculations and discussion are appropriate for the undergraduate physical chemistry laboratory as either an independent dry lab or a supplement to a pre-existing vibrational spectroscopy lab. [ABSTRACT FROM AUTHOR]

Lactone-size identification of d-ribonolactone derivatives has been debated for four decades due to complex lactone-ring rearrangements and acetal migration. This laboratory experiment for an upper-division undergraduate organic chemistry laboratory course describes a fast and reliable assignment of lactone-size derivatives from d-ribose using ¹H and ¹H-¹H NOESY NMR spectroscopy. In addition, the further derivatization of these lactones via O-acylation is described, followed by a theoretical study that allows conformational analysis of these molecules in solution using JANOCCHIO software. Overall, this experiment uses simple, inexpensive, and commercially available reagents, and the reactions are performed in mild conditions. The products are solid and can be either purified by crystallization or used directly in the next step of the synthesis. 13C, 2D ¹H-¹H COSY, and ¹H-13C HMQC or HSQC spectra are also analyzed. Therefore, this laboratory experiment allows students to explore several NMR techniques and relate them with basic NMR concepts, such as scalar coupling constants related to dihedral angles and the NOE effect, to predict lactone-size and conformation of the synthesized molecules in solution. [ABSTRACT FROM AUTHOR]

A two-part experiment using bubble rafts to analyze amorphous structures is presented. In the first part, the distinctions between crystalline and vitreous structures are examined. In the second part, the interface between crystalline and amorphous regions is considered. Bubble rafts are easy to produce and provide excellent analogy to recent research results on the atomic structure of silica glass. Ring statistics are employed to characterize the 2D structures and results from student bubble raft data are compared to results from atomically resolved images of amorphous 2D silica; the bubble rafts demonstrate good qualitative agreement. In these experiments, students learn how to characterize crystalline and amorphous materials and are introduced to current research results and analysis techniques for amorphous material structures. [ABSTRACT FROM AUTHOR]

A synthetic procedure is outlined where upper-level undergraduate organic chemistry students perform a two-week, semimicroscale aza-Baylis-Hillman reaction to generate an allylic sulfonamide product. Students evaluate several green chemistry reaction metrics of industrial importance (process mass intensity (PMI), E factor, and reaction mass efficiency) and specifically learn the pivotal role that PMI plays in improving operational sustainability. Advantages and disadvantages of the various metrics are highlighted within the context of a multicomponent transformation eliciting current research activity. [ABSTRACT FROM AUTHOR]

A demonstration to highlight the utility and ease of handling environmentally benign magnetically recoverable nanoparticle catalysts is described. The demonstration offers two powerful visuals. The first is a color change oxidation of tetramethylbenzidine by hydrogen peroxide catalyzed by Fe3O4 nanoparticles. The second, and more pedagogically relevant to discussion of catalyst recycling, is the retrieval of these nanoparticles from solution with an external magnet and subsequent reuse for further rounds of catalysis. The demonstration, useful to instructors of general chemistry and green chemistry courses or animators of outreach activities, requires a modest time investment of less than 5 min, yet adds striking visual aids to discussions of catalyst recycling and reuse. [ABSTRACT FROM AUTHOR]

A laboratory experiment in which students synthesize Ag, Au, and Pt nanoparticles (NPs) and use them to modify screen printed carbon electrodes for the electroanalysis of the hydrogen peroxide content in commercially available teeth whitening strips is described. This experiment is designed for two 3-h laboratory periods and can be adapted for upper-division undergraduate students in instrumental analysis, materials science, or physical chemistry laboratories. The experiment presented has already been used as a hands-on component in a Functional Nanomaterials Course, which exposed students to the analysis of the electrochemical properties of metal nanoparticles. Moreover, it allows for teaching the basics of nanoparticle synthesis and enables students to learn the fundamentals of electrochemical sensing with nanostructured materials. [ABSTRACT FROM AUTHOR]

A research project for senior undergraduates of chemistry has been developed to introduce syntheses of a series of monodispersed semiconductor PbS quantum dots (QDs) and their characterization methodologies. In this paper, we report the preparation of monodispersed semiconductor PbS QDs with sizes smaller than the exciton Bohr radius using a simple, one-step process, and the characterization of the QDs using a range of instruments, including Fourier-transform infrared spectroscopy, transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and energy-dispersive X-ray spectroscopy. Our synthesis approach involves dissolving powdered sulfur (as the S precursor) in 1-tetradecene and adding PbCl2 as the Pb precursor to the suspension as well as oleylamine as a capping ligand. The PbS QD project represents, we believe, an almost ideal opportunity to provide exposure of undergraduate students to nanotechnology research via syntheses and characterization of semiconductor nanoparticles. [ABSTRACT FROM AUTHOR]

This paper presents a simplified approach for the application of material efficiency metrics to linear and convergent synthesis plans encountered in organic synthesis courses. Computations are facilitated and automated using intuitively designed Microsoft Excel spreadsheets without invoking abstract mathematical formulas. The merits of this approach include (a) direct application of green chemistry principles to synthesis planning; (b) strongly linking green metrics calculations and synthesis strategy; (c) pinpoint identification of strengths and weaknesses of any synthesis plan's material efficiency performance using effective visual aids; (d) in-depth quantitative and qualitative critiquing of synthesis plan performance and strategy; and (e) giving opportunities to students to offer insightful suggestions to improve or "green up" published procedures based on their growing personal database of chemical reactions as they continue their education in chemistry. An extensive database of over 600 examples taken from Organic Syntheses was created as a repository of reliable examples that instructors can draw upon to create meaningful classroom pedagogical exercises and homework problem sets that couple material efficiency green metrics analyses and traditional learning of organic chemistry. [ABSTRACT FROM AUTHOR]

A series of pedagogical problem set exercises are posed that illustrate the principles behind material efficiency green metrics and their application in developing a deeper understanding of reaction and synthesis plan analysis and strategies to optimize them. Rigorous, yet simple, mathematical proofs are given for some of the fundamental concepts, particularly how metrics for overall plan material performance are related to their composite counterparts for individual reactions. Throughout this exposition, whenever a synthesis scheme is examined, it is converted into a compact tree diagram that is used to depict plans of any degree of complexity (linear or convergent) as a means to conveniently keep track of all reagents, intermediates, reaction yields, stoichiometric coefficients, number of branches, number of reaction steps, and convergent steps. We demonstrate that such tree diagrams facilitate the computation of material efficiency metrics for any individual reaction in a plan as well as for the entire plan. We also show how such diagrams may be used to plan schedules for reaction operations when multiple linear branches are run concurrently. For brevity the Supporting Information contains full solutions to posed problems. [ABSTRACT FROM AUTHOR]

This article describes a synergistic two-semester writing sequence for biochemistry courses. In the first semester, students select a putative protein and are tasked with researching their protein largely through bioinformatics resources. In the second semester, students develop original ideas and present them in the form of a research grant proposal. Both projects involve multiple drafts and peer review. The complementarity of the projects increases student exposure to bioinformatics and literature resources, fosters higher-order thinking skills, and develops teamwork and communication skills. Student feedback and responses on perception surveys demonstrated that the students viewed both projects as favorable learning experiences. [ABSTRACT FROM AUTHOR]

A simple, robust, and reproducible method was developed for the isolation of (-)-menthol from peppermint oil and to study the effect of different types of leaving groups, catalysts, solvents, and tertiary base on the extent of esterification of (-)-menthol to (-)-menthyl acetate. In this experiment, students compare leaving group properties of acetate and chloride ions from the acylating reagents acetic anhydride and acetyl chloride, respectively. The extent of conversion is compared when pyridine and 4-(dimethylamino)pyridine are used as catalysts, when N,N-diisopropylethylamine is used as tertiary base, and when the solvent is changed from dichloromethane to diethyl ether to N,N-dimethylformamide. Students are assessed on the chromatographic/spectroscopic purity and yield of (-)-menthol isolated and on their understanding of the factors that affect its extent of conversion to (-)-menthyl acetate. Full spectral characterization of both compounds is also conducted. They also complete a series of answers to questions based on lecture material presented on this topic, complete a crossword as a formative assessment tool, and are required to present a PowerPoint slide to their peers on a particular aspect of the bench to bedside development of peppermint oil for the treatment of irritable bowel syndrome. [ABSTRACT FROM AUTHOR]

A simple photometric assembly based in an LED as a light source and a photodiode as a detector is proposed in order to follow the absorbance changes as a function of the titrant volume added during the course of acid--base titrations in the presence of a suitable visual indicator. The simplicity and low cost of the electronic device allow the students to easily assemble the photometer and use it as a titration detector. The choice of the appropriate LED color should also demonstrate the principles of complementary colors. Concepts of data handling and relationship between the pH of the titration end point and indicator choice can be addressed. Errors associated with the use of wrong indicators can be demonstrated. The circuit assembly can highlight for the students the instrumentation and automation importance in modern chemical analysis. The discussion can be extended to relevant issues involved in this matter, such as light absorption, circuit analysis, and the hydrolysis concept, once they are involved and are closely related with the results obtained. [ABSTRACT FROM AUTHOR]

This work presents an approach that integrates the preparation of a coordination compound, potassium tris- (oxalato)ferrate(III), with its photochemical behavior and provides a possible application, the printing of a photograph using the cyanotype technique. Through this experiment, students can be taught several concepts that occur in a coordination chemistry course, including the thermodynamic aspects of forming a compound, its photochemistry, the detection of its photoproducts, and the observation of the formation of a new compound and the resulting intervalence band, which generates the blue print. [ABSTRACT FROM AUTHOR]

The definition of the kilogram, the unit of mass in the International System of Units (SI), has not changed in more than 125 years. The kilogram is still defined by the mass of a Pt--Ir cylinder conserved at the International Bureau of Weights and Measures. Science and technology have progressed to the point where it is likely the kilogram will be redefined in 2018 in terms of a constant of physics--the Planck constant, which is closely linked to the Avogadro and atomic mass constants. In this article, we illustrate by means of a simple experiment on how analytical chemistry is contributing to this project, how the new definition of the kilogram will be put into practice and what it may mean for chemists. Surprisingly, perhaps, this simple experiment allows us to determine the mass of an aluminum-27 atom, the mass of a carbon-12 atom (and the atomic mass constant), the Avogadro constant, and the Planck constant--all with uncertainty less than 1%--in close analogy to the way the most accurate experiment of this type achieves an uncertainty of parts in 108. Finally, we point out that a very different area of modern technology, namely voltage and resistance measurements using quantum electrical devices, provides a second high-accuracy way to implement the new definition. [ABSTRACT FROM AUTHOR]

The expansion or compression of gas confined in a pistonand- cylinder device is a classic working example used for illustrating the First and Second Laws of Thermodynamics. The balance of energy and entropy enables the estimation of a number of thermodynamic properties. The entropy generation (also called entropy production) resulting from this process can also be used to determine the feasibility and reversibility of a process. In this work, we present an extended discussion involving quantitative analysis of the effects of friction between a piston and the interior wall of a cylinder. Our findings indicate that the friction force caused by the movement of the piston is a main source of entropy generation in this process. This explanation does not appear in most textbooks dealing with similar problems. We also discuss, from a quantitative perspective, the effects of friction on the dynamic physical and thermodynamic properties, including entropy generation. Our findings suggest that engaging students in a discussion related to piston-and-cylinder problems involving the effects of friction could provide valuable insight into entropy generation in practical applications. [ABSTRACT FROM AUTHOR]

This series of three practical sessions centers on drugs that inhibit the enzyme acetylcholineesterase. This enzyme is responsible for the inactivation of acetylcholine and has been the target of drugs to treat glaucoma and Alzheimer's disease and for a number of insecticides and warfare agents. These sessions relate to a series of carbamate inhibitors that are classed as slowly reversible anticholinesterases and show how structure--activity relationships can guide the development of drug molecules. In Practical 1, each student group synthesizes one carbamate inhibitor of acetylcholinesterase. In Practical 2, students measure the activity of their inhibitor to derive an IC50 value suitable for comparison with the other derivatives made by the class. In Practical 3, students gain firsthand experience with structure--activity methods, such as a Hansch analysis, to investigate whether these can be used to make predictions of the activity of related compounds based on structural properties. This series gives students a rare insight into a number of the important aspects of drug discovery, that of drug synthesis, activity testing, and the construction of subsequent quantitative structure--activity relationships (QSARs). [ABSTRACT FROM AUTHOR]

The Paternò-Büchi photocycloaddition reaction is used as the basis for physical--organic final-year undergraduate laboratory experiments designed to emphasize the multidisciplinary approach to modern-day chemical practice. These reactions are performed using commercially available LED-based light sources, which offer a convenient and safe tool for teaching photochemistry. Using a series of substituted benzaldehydes and furan, experiments can be conducted to measure reaction rates and to isolate the products for structure determination. The experiments are deliberately broad in scope, covering mechanistic photochemistry, chemical kinetics, and photochemical organic synthesis in a holistic manner in order to demonstrate to students how topics usually taught separately are brought together. The reported experimental program also offers actinometry and quantum yield determinations, as well as NMR-based structural analysis, as potential routes for further elaboration of the experimental program [ABSTRACT FROM AUTHOR]

An exercise in molecular modeling that demonstrates the distinctive features of Fischer and Schrock carbene complexes is presented. Semi-empirical calculations (PM3) demonstrate the singlet ground electronic state, restricted rotation about the C-Y bond, the positive charge on the carbon atom, and hence, the electrophilic nature of the Fischer carbene complex. Likewise, the triplet ground state of the Schrock carbene complex, along with the negative charge on the carbon atom and nucleophilic behavior, is also demonstrated. [ABSTRACT FROM AUTHOR]

Here we present the development of a 13 week project-oriented biochemistry laboratory designed to introduce students to foundational biochemical techniques and then enable students to perform original research projects once they have mastered these techniques. In particular, we describe a semester-long laboratory that focuses on a biomedically relevant enzyme- Helicobacter pylori ( Hp) urease-the activity of which is absolutely required for the gastric pathogen Hp to colonize the human stomach. Over the course of the semester, students undertake a biochemical purification of Hp urease, assess the success of their purification, and investigate the activity of their purified enzyme. In the final weeks of the semester, students design and implement their own experiments to study Hp urease. This laboratory provides students with an understanding of the importance of biochemistry in human health while empowering them to engage in an active area of research. © 2015 by The International Union of Biochemistry and Molecular Biology, 43(5):333-340, 2015. [ABSTRACT FROM AUTHOR]

A fluorescence demonstration is described that incorporates several fundamental aspects of an introductory biochemistry course. A variation of a known leakage assay is utilized to prepare vesicles containing a quenched fluorophore. The vesicles are exposed to several osmotic environments ranging from isotonic to hypotonic. The degree of vesicle swelling, partial rupture or bursting, and subsequent release and dequenching of the encapsulated fluorophore can be observed. This demonstration introduces students to fluorescence, fluorescence quenching, lipid membrane dynamics, membrane permeability, and osmotic pressure. Students are also introduced to the lipid extrusion process and are able to observe the separation of compounds via size exclusion chromatography. This demonstration has the flexibility to be expanded to laboratory experiments that allow students to investigate a variety of membrane properties. [ABSTRACT FROM AUTHOR]

A multistep synthesis of 10-ethyl flavin was developed as an organic chemistry laboratory experiment for upper-division undergraduate students. Students synthesize 10- ethyl flavin as a bright yellow solid via a five-step sequence. The experiment introduces students to various hands-on experimental organic synthetic techniques, such as column chromatography, thin layer chromatography (TLC), extraction techniques, and characterizing intermediates and final products by IR and NMR spectroscopy. It also provides an opportunity for students to review important topics such as nucleophilic substitution reactions, hydrolysis of amides, condensation reactions, and reduction of aromatic nitro groups to amines. [ABSTRACT FROM AUTHOR]

An undergraduate analytical chemistry course has been adapted to a flipped course format. Course content was provided by video clips, text, graphics, audio, and simple animations organized as concept maps using the cloud-based presentation platform, Prezi. The advantages of using Prezi to present course content in a flipped course format are discussed. Results of an American Chemical Society analytical chemistry examination were encouraging. Results of pre- and postsurveys of student perception of their learning are summarized. [ABSTRACT FROM AUTHOR]

To provide a research-like experience to upper-division undergraduate students in a biochemistry teaching laboratory, isothermal titration calorimetry (ITC) is employed to determine the binding constants of lysozyme and its inhibitors, N-acetyl glucosamine trimer (NAG3) and monomer (NAG). The extremely weak binding of lysozyme/NAG is determined using a competitive binding assay. Such interactions between lysozyme and its inhibitors are visualized with PyMol software, by which the hydrogen bond formation in the complexes is used to explain the binding specificity. The hydrogen bond inventory in the binding interface correlates with the heat enthalpy determined or derived from ITC measurements. A possible explanation for such a correlation is presented and used for an extensive discussion in thermodynamics and ligand--receptor interactions. This laboratory exercise stimulates students' critical thinking about weak/strong binding interactions and the relationship between thermodynamics and structural changes. [ABSTRACT FROM AUTHOR]

The synthesis of (Z)-4-(4-nitrobenzylidene)-2-phenyloxazol-5(4H)-one, which is a potent immunomodulator and tyrosinase inhibitor, is described as an experiment for an upper-division undergraduate organic chemistry laboratory course. This compound is produced via an Erlenmeyer-Plöchl reaction in the absence of any additional solvents and is isolated without need of preparative chromatography, yielding up to 97% of product. [ABSTRACT FROM AUTHOR]

Industrial purification of biomolecules is commonly based on a sequence of chromatographic processes, which are adapted slightly to new target components, as the time to market is crucial. To improve time and material efficiency, modeling is increasingly used to determine optimal operating conditions, thus providing new challenges for current and future bioengineers. At the Karlsruhe Institute of Technology (KIT), mechanistic modeling of protein chromatography has long been part of the curriculum of the Bioengineering master's degree program, supported by exercises using simulation software. Emphasis lies on nonlinear preparative chromatography, where the result strongly depends on the sample concentration. For undergraduate students to gain hands-on experience in model-based optimization, a three-week, in-depth laboratory course was designed on the purification of a ternary mixture of proteins using ion-exchange chromatography and mechanistic modeling. Students apply in-house software ChromX, which is made available for download, together with tutorials on numerics and practical applications. This article presents the working principle of ChromX and results of the laboratory course for undergraduate students. [ABSTRACT FROM AUTHOR]

Cyclic voltammetry (CV) is a popular technique for the study of electrochemical mechanisms because the method can provide useful information on the redox couple. The technique involves the application of a potential ramp on an unstirred solution while the current is monitored, and then the ramp is reversed for a return sweep. CV is sometimes introduced in undergraduate chemistry laboratories. The CV waveform is dependent on several processes including charge transfer, diffusion, and coupled homogeneous reactions. Computer simulations are sometimes used to study these effects. An easy-to-use CV simulator was written in Microsoft Excel for the purpose of teaching undergraduate students and to serve as an entryway to more sophisticated electrochemical simulations. [ABSTRACT FROM AUTHOR]

A nationwide survey of the undergraduate physical chemistry course was conducted to investigate the depth and breadth of content that is covered, how content is delivered, how student understanding is assessed, and the experiences and beliefs of instructors. The survey was administered to instructors of physical chemistry (N = 331) at American Chemical Society certified colleges and universities in the United States. The majority of instructors (N = 187) provided contact information, allowing responses to be associated with their institution. The goal of this preliminary study is to provide an awareness of the current state of physical chemistry courses across the United States. Several relationships regarding the course curriculum were investigated such as depth versus breadth of course content, and goal for understanding versus types of assessment questions. Also, several relationships regarding instructor beliefs and experiences were investigated such as degree of teacher preparation experience versus course delivery, and instructor beliefs about the challenging nature of physical chemistry education versus proposed strategies to overcome those challenges. Information gained from this study may inform the development of new teaching practices, curriculum, assessments, and resources for physical chemistry education, as well as encourage instructors of physical chemistry and researches of chemical education to work together to improve student understanding of physical chemistry. [ABSTRACT FROM AUTHOR]

In this experiment, students carry out a modern organocatalytic reaction using IMes-HCl and NaOH to catalyze the formation of 1,3,4-triphenylcyclopentene from cinnamaldehyde and chalcone in water. Deprotonation of IMes-HCl with NaOH forms the AT-heterocyclic carbene IMes that reacts with cinnamaldehyde to form a homoenolate equivalent of cinnamate, which undergoes a conjugate addition to chalcone followed by an intramolecular aldol reaction to form a cyclopentane. Formation of a β-lactone and decarboxylation leads to 1,3,4-triphenylcyclopentene. This reaction introduces students to both organocatalysis and the use of carbonyl anion and homoenolate equivalents in synthesis. This novel and interesting chemistry was first reported in 2006, and the reaction was modified to be carried out in water under an air atmosphere in 2013. The very nonpolar product is easily purified chromatographically. The aliphatic protons form a somewhat complex pattern due to allylic and homoallylic coupling, but with no overlap, so that students can simulate the spectrum perfectly using Web-based software. This experiment can be combined with one of the four preparations of IMes-HCl reported in this Journal, which all use IMes as a ligand rather than an organocatalyst. [ABSTRACT FROM AUTHOR]

An experiment carried out by advanced undergraduate students in a project- based laboratory course is described. Taking into account the positive effects of working in teams, which has been key for successful research in industry and academia, a cooperative learning experience in the laboratory was developed. Students working in teams of four synthesize two alkaloid-derived thioureas starting from a chiral pool (quinidine and quinine). The thioureas are used to catalyze an enantioselective Michael reaction between acetylacetone and frans-4-methyl-β-nitrostyrene, providing a platform for discussion of stereochemistry and chirality transfer events. Qualitative analysis of the reaction enantioselectivity is performed by polarimetry, which allows students to assign product optical rotations (+ /-) with their absolute configurations (S/R). Students are exposed to an entire research process: analysis of primary literature, discussion with colleagues, planning laboratory schedules, and execution of experiments. [ABSTRACT FROM AUTHOR]

The coupling of a student experiment involving the preparation and use of a catalyst for the asymmetric epoxidation of an alkene with computational simulations of various properties of the resulting epoxide is set out in the form of a software toolbox from which students select appropriate components. At the core of these are the computational spectroscopic tools, whereby a measured spectrum can be interpreted in some detail using theoretical simulations. These include a range of modern chiroptical methods to accompany the increased use of such techniques in modern teaching laboratories. Computational experiments are captured in a Wiki-based electronic laboratory notebook, which features data-stamping, authenticated entries, and inclusion of semantically intact data via interactive models rendered within the Wiki using JSmol and its referencing via a digital object identifier (DOl) to a digital data repository. [ABSTRACT FROM AUTHOR]

In today's complex world, there is a continued demand for recently graduated forensic chemists (criminalists) who have some background in forensic experimental techniques. This article describes modern forensic experimental approaches designed and implemented from a unique instructional perspective to present certain facets of crime scene investigation. Physical evidence collection, handling, and evaluation are reviewed, as are challenges associated with carrying out these tasks. The interrelation of the responsibilities of the crime scene investigator and criminalist also is addressed, as this can be highlighted in an instructional setting. If the investigator does not collect sufficient evidence or collects the evidence improperly, the criminalist will be unable to effectively interpret the data. In this report, the authors describe their experiences at a mock crime scene designed for investigation by undergraduate forensic science students. Key points that must be considered include evidence collection, analysis of the evidence, interpretation of the results, and drawing conclusions from those interpretations. We have presented the information in a way that may be beneficial to instructors looking to create or update existing forensic science courses, or scholars interested in the drawbacks of certain aspects of evidence collection. [ABSTRACT FROM AUTHOR]

Wildfires lead to the loss of life and property in many parts of the world. Understanding their dangers and, more particularly, the underlying dynamics which lead to fires of catastrophic scale contributes to better awareness as well as prevention and firefighting capabilities within the affected areas. In order to enable a basic understanding of the mechanisms of fire propagation for high school and college students, we present here simple model experiments using match sticks that demonstrate the dangers of spatial coupling between individual reactive (combustible) elements leading to rapid spreading of the combustion reaction. Supplemented with easy-to-grasp numerical simulations, our work illustrates the dynamics of wildfires in impressive but controllable ways and puts wildfire propagation into the fascinating framework of excitable active media which have many equivalents in chemical, ecological, biological or societal systems. [ABSTRACT FROM AUTHOR]

In this article, the strategies and techniques used to successfully teach advanced inorganic chemistry, in the lecture and laboratory, to a legally blind student are described. At Fairfield University, these separate courses, which have a physical chemistry corequisite or a prerequisite, are taught for junior and senior chemistry and biochemistry majors. A student earns a separate grade in each the lecture (three credits) and the laboratory course (two credits). An overview of the course topics is given, followed by general accommodations and specific approaches that were used. Student assistants were very helpful and provided extra support for the blind student. Student assistants were utilized for the laboratory course, problem sets, and exams. Specific examples and detailed explanations of approaches that were helpful to the legally blind student throughout the entire course are provided. The legally blind student benefited from extensive, verbal description of complexes, figures, and diagrams. In addition, the student benefited from tactile description of figures and models. The student assistants and extra office hours were essential for the blind student to succeed and excel in advanced inorganic chemistry. The approaches discussed in this paper are the product of immediate and continual feedback from the student over the course of the semester. The student would frequently comment after class that he followed the lesson or was confused, and the latter comment elicited experimentation with different approaches. [ABSTRACT FROM AUTHOR]

A ´H NMR spectroscopy-based laboratory experiment explores mono- and disaccharide structural chemistry, and the enzyme-substrate specificity of glycosidic bond cleavage by β-glucosidase towards cellobiose (β-linked gluco-disaccharide) and maltose (α-linked gluco-disaccharide). Structural differences between cellobiose, maltose, and the glycolytic product glucose are established in terms of chemical shift changes and J-coupling constants of the anomeric proton peaks. The distinct anomeric proton signals observed in the 4.0-5.5 ppm range of glucose, cellobiose, and maltose spectra serve as a signature NMR feature to monitor the substrate specificity of β-glucosidase towards cellobiose as a substrate. This experiment consolidates carbohydrate structural chemistry and NMR spectroscopy as applied to investigate enzyme specificity in the context of a biochemistry laboratory experiment with hands-on NMR experience for upper-division undergraduates. [ABSTRACT FROM AUTHOR]

An integrative laboratory study addressing fundamentals of enzyme catalysis and their application to reactors operation and modeling is presented. Invertase, a β-fructofuranosidase that catalyses the hydrolysis of sucrose, is used as the model enzyme at optimal conditions (pH 4.5 and 45 °C). The experimental work involves 3 h of laboratory time for each student per week over four weeks. Students, organized in laboratory sessions of three groups with 3 or 4 students per group, work in a collaborative manner to obtain a set of replicates of initial reaction rate for different substrate concentrations, using both free and calcium alginate-immobilized Saccharomyces bayanus cells containing biologically active invertase. The results are shared by all of the groups for statistical data treatment, calculation of Michaelis-Menten kinetic parameters, and modeling of three types of classical reactors, a Continuous Stirred Tank Reactor (CSTR), a Plug Flow Reactor (PFR), and a Fluidized Bed Reactor (FBR), operating in continuous mode with immobilized invertase. For each reactor, the experimental conversion profile as a function of the feed flow rate is compared to predicted profiles based upon the kinetic parameters obtained. [ABSTRACT FROM AUTHOR]

A homology modeling laboratory experiment has been developed for an introductory molecular modeling course for upper-division undergraduate chemistry students. With this experiment, students gain practical experience in homology model preparation and assessment as well as in protein visualization using the educational version of PyMOL state-of-the-art molecular graphics. Students create a human serum albumin homology model with relatively high resolution at 1.77 Å (heavy atom model) and with reasonable values for bond lengths, angles, and dihedrals. The suggested tasks integrate different fundamental aspects of structural biology and protein modeling. Ramachandran plots and side chain rotamers are discussed. The assignments are shown to be good not only to teach homology modeling basics, but also to introduce several other concepts of structural bioinformatics such as protein sequence data mining, basic local alignment search tool (BLAST), and multiple sequence alignment. Homology modeling is demonstrated to be a cornerstone in molecular docking and drug design projects if the crystal structure of the protein of interest is not yet determined. [ABSTRACT FROM AUTHOR]

A flexible, rigorous laboratory experiment for upper-level biochemistry undergraduates is described that focuses on the Roundup Ready maize line. The work is appropriate for undergraduate laboratory courses that integrate biochemistry, molecular biology, or bioinformatics. In this experiment, DNA is extracted and purified from maize kernel and leaf samples collected from a Roundup Ready maize grower's field. A small segment of DNA (108 base pairs) specific to the Roundup Ready transgene that codes for CP4 5-enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) is amplified with polymerase chain reaction (PCR) to detect the presence of the gene in the maize samples. Students additionally choose a protein closely related to CP4 EPSPS as determined by amino acid sequence alignments. The selected amino acid sequences are submitted to an online protein modeling program where students compare their protein with the herbicide-resistant enzyme found in Roundup Ready crops. This experimental paradigm gives students a physical appreciation for the central dogma of biology, as they are exposed to products derived from the replication, transcription, and translation events belonging to a genetically modified crop. The PCR portion of the laboratory allows students to perform an in vitro replication of a portion of the NK603 transgene and identify the segment via ultraviolet radiation. In direct connection to the PCR portion, the protein structure elucidation gives rise to the central ideas of evolution--that slight changes in the genetic code of DNA, translated into proteins, produce novel protein structures with significantly different function. [ABSTRACT FROM AUTHOR]

A five-week miniproject is described for an upper-division experimental organic chemistry course. The activities include synthesis of a phenylboronic acid via a Grignard reaction and its use in a Suzuki-Miyaura cross-coupling reaction. Technical skills and concepts normally presented in practical organic chemistry courses are covered, including the use of an inert atmosphere (Schlenk tube technique), separation of mixtures (filtration), melting range determination, infrared (IR) spectrum, stoichiometric calculations and gas chromatography techniques. [ABSTRACT FROM AUTHOR]

The rapid academic and industrial development of nanotechnology has led to its implementation in laboratory teaching for undergraduate-level chemistry and engineering students. This laboratory experiment introduces the galvanic replacement reaction for synthesis of hollow metal nanoparticles and investigates the optical properties of these nanoparticles. Changes of localized surface plasmon resonance from solid to hollow nanoparticles are monitored by UV-vis spectroscopy, while corresponding morphological changes are validated by transmission electron microscopy. The optical properties are further investigated by the use of a laser pointer, laser irradiation, and surface-enhanced Raman spectroscopy. By performing these experiments, students gain practical knowledge for the synthesis of hollow metal nanoparticles and the underlying structure-dependent optical properties. [ABSTRACT FROM AUTHOR]

An interdisciplinary laboratory experiment involving second-year undergraduate organic chemistry and introductory inorganic chemistry undergraduate students is described. Organic chemistry students prepare a series of amine-bis(phenols) via a Mannich reaction, and characterize their products using melting point; FTIR; and ¹H, 13C, DEPT-135, and HSQC NMR experiments. In the inorganic chemistry laboratory, students utilize these amine ligands to prepare a series of octahedral titanium complexes, and characterize the resultant complexes using FTIR, and ¹H, 13C, DEPT-135, and HSQC NMR spectroscopy. Students are asked to revisit concepts such as the two- and three-dimensional representations of their target molecules and reaction mechanisms throughout both experiments. From these experiments, students gain an appreciation for the multidisciplinary nature of chemistry. [ABSTRACT FROM AUTHOR]

The stated purpose of this article is to provide teachers an inexpensive model for laboratory activity and demonstration of galvanic cells using a paper-based device. Metal strips, metal solutions, and KNO3 solution serve as electrodes, metal ions, and electrolyte, respectively. A paper-based device is not only a support for reactions, but also a salt bridge for electrolyte. This activity ought to be interesting to all levels of chemistry from middle school classes through potential applications in upper division college classes. Furthermore, teachers may design and fabricate a paper-based device for their classes in chemistry and also related fields. [ABSTRACT FROM AUTHOR]