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Most chemistry students struggle with interpreting and understanding NMR (nuclear magnetic resonance) spectra and the general concepts of NMR spectroscopy. NMR spectroscopy seems to be difficult to both teach and learn. Therefore, the corresponding courses should be investigated in more detail. We conducted a survey with N = 39 German university lecturers in NMR spectroscopy on their course content as well as on their estimations on the importance of certain topics for understanding NMR spectroscopy in detail and found the most recent problems, conceptions, and content structure. The participants were asked to rate a list of items (belonging to [superscript 1]H NMR spectroscopy) twice: First in terms of appearance in their lecture or course and second according to their personal relevance. Our results showed that, on the one hand, students learn about the physical and chemical backgrounds and theoretical basics for understanding [superscript 1]H NMR spectroscopy and, on the other hand, about essential knowledge for practical analyzing and interpreting [superscript 1]H NMR spectra. The most covered and most important topics are the practical ones related to spectra interpretation, e.g., chemical shift, spin-spin coupling, and further background knowledge for peak analysis. Therefore, most lecturers focus on teaching usage-oriented conceptual knowledge more than theoretical backgrounds, which means that analyzing spectra is paramount, especially for beginner students. Furthermore, this review visualizes an evidence-based ranking for the most covered and as most relevant estimated NMR spectroscopy lecture contents as well as students' greatest learning difficulties in Germany. Lecturers and students are now able to validate their lectures or course structure.

A didactic sequence is proposed using an infrared puzzle and a didactic questionnaire for the teaching-learning of infrared spectroscopy at the upper secondary level. The didactic sequence that was designed was implemented in person in the subject of Chemistry IV at the high school level, corresponding to the sixth semester of the curriculum of the National School of Sciences and Humanities (CCH), Vallejo Campus, of the National Autonomous University of Mexico. In the didactic sequence, students understand the importance of functional groups where they determine organic compounds, by identifying regularities, properties, and structure of alcohols, aldehydes, ketones, and carboxylic acids. After applying the didactic sequence, a post-test questionnaire was applied, and the results showed that the students significantly improved their knowledge of IR when using the puzzle that allowed them to correctly identify the bands that identify the carbonyl group.

Students in a typical instrumental analysis course may learn more than 30 analytical techniques. There are more than 150 components associated with the instrumentation that they learn. To help students organize this large amount of information, we classified these components into four categories: sources, samples, discriminators, and detectors. In this work, color-coded pictograms are used to help students identify components associated with a particular instrumental technique. For example, a UV-visible spectrophotometer can be depicted by using four color-coded pictograms. Pictograms were created for instrumentation on each of the following topics: spectroscopy, electrochemistry, chromatography, elemental analysis, surface analysis, and thermal analysis. Methods to incorporate these pictograms into the instrumental analysis course and assess their effectiveness are provided.

We present a showcase of our experience with videos complementing analytical chemistry lectures to familiarize undergraduate students with instrumental element analysis. This includes a detailed account of how we planned, produced, and utilized a video to review the course content at the end of the semester. The analytical case study focused on the determination of magnesium in two well water samples with emphasis on flame atomic absorption spectroscopy, while also comparing results with inductively coupled plasma optical emission spectroscopy and titration measurements. During the lecture, we engaged students by asking them for suggestions on how to carry out the measurements before showing the respective video sections. A survey among the students revealed a remarkably positive response to this approach. We demonstrate our video production approach by making decisions and choices from the video production, such as recording and editing, explicit and conclude with practical advice for planning and producing similar videos to visualize case studies.

Triboluminescence is a fascinating phenomenon that can engage students' interest in chemistry. However, safe, cost-effective, and accessible laboratory experiments featuring highly triboluminescent substances are limited. To bridge this gap, we present a simple, rapid, semimicro test tube preparation of the visually engaging manganese complex [MnBr[subscript 2](Ph[subscript 3]PO)[subscript 2]], conducted by high school students. During the laboratory session, students practice various laboratory skills, including handling semimicro quantities of substances, ascertaining the melting point, and recrystallizing the synthesized complex. They also investigate the complex's triboluminescent, fluorescent, and magnetic properties through straightforward and illustrative experiments. Furthermore, this laboratory activity has been successfully implemented in an undergraduate chemistry didactics course for chemistry educators. The experiment's simplicity, combined with the safety of starting materials and use of nontoxic solvents, makes it an optimal choice for a variety of educational environments, such as high school and university laboratory sessions, science clubs, and public science outreach activities.

Chemometric techniques such as partial least-squares (PLS) regression have been applied with huge success to a wide array of chemical problems including multicomponent analysis of analytes in complex mixtures. Despite this, there are few examples of laboratory pedagogical exercises that involve students in the acquisition of chemical data from infrared spectroscopic-based instrumentation, followed by quantitative chemometric analysis using PLS. In this article, we present a computational activity that introduces undergraduate students in an instrumental analysis laboratory setting to data acquisition using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy followed by data analysis using PLS. The first part of the activity involved students creating mixture designs of binary terpene components consisting of p-cymene and limonene. These mixtures were then analyzed using an ATR-FTIR spectrometer, where students became familiarized with the instrument and were shown how to characterize and differentiate the aforementioned terpenes using their generated FTIR spectra. The second part of the activity involved preprocessing the acquired FTIR spectral data from the first part followed by the simultaneous quantitative determination of the prepared terpenes using PLS. On the basis of student surveys, it can be concluded that this convenient and inexpensive activity was ultimately successful in introducing students to the use of chemometrics for quantitative analysis of terpenes using an ATR-FTIR. This easy-to-do two-week activity can be used as a standalone for instrumental analysis laboratory classes and can even be integrated in advanced courses in applied spectroscopy and chemometrics.

Quinacridone red and violet are visually different colors, an observation confirmed by their visible reflectance spectra and CIE L*a*b* coordinates. However, their IR spectra are extremely similar. Though chemically identical, the two quinacridones are polymorphs. In this experiment, designed for and tested by nonscience majors, the pigments are extracted from oil paints with hexane in a short procedure involving sonification and centrifugation. ATR-FTIR spectra of the recovered brilliantly colored powders reveal the presence of a calcium carbonate filler in one of the two paints. Factoring out the carbonate bands, the spectra are nearly identical. Students must reconcile the evidence of color and the evidence of the spectra.

Vibrational fine structure observed in the published He-I UV photoelectron spectra of H[subscript 2] and N[subscript 2] molecules recorded at room temperature and under microwave excitation or at 700 °C have been reexamined and compared with calculations of the Franck-Condon factors (FCFs) using simple harmonic oscillator wave functions and/or those obtained using Morse potentials. In general, FCFs are used to explain vibronic transitions of molecules observed in the UV-vis and photoelectron spectra of diatomic and polyatomic molecules, which can be computed using differing levels of complexity. We advocate constructing the vibrational wave functions numerically, rather than analytically, with the help of a program such as Excel, Origin, or Python. In this way students can also verify the normalization and orthogonality of the wave functions using numerical integration routes provided within these programs. Special attention is drawn to possible deviations of the FCFs of the vibrationally excited molecules from those of the ground states.

Quantum dots are colloidal semiconductor nanocrystals that display size-dependent electronic and optical properties. These materials are a visual demonstration of a quantum-mechanical effect. Here we present a laboratory exercise for undergraduate/Bachelor students as an introduction to colloidal nanocrystals and quantum dots. The students synthesize three sizes of indium phosphide (InP) nanocrystals and perform one core/shell synthesis of indium phosphide cores shelled with zinc sulfide (InP/ZnS). The obtained quantum dots are characterized by quantitative UV--vis, photoluminescence, and 1H NMR spectroscopy. Students are acquainted with several concepts: nanocrystal synthesis, colloids, Beer-Lambert law, quantum confinement, photoluminescence, and surface chemistry. For each concept, background information is provided, rendering this report a comprehensive introduction for students and teachers. Indium phosphide is a safer material to handle in the undergraduate lab compared to cadmium selenide (CdSe), cesium lead bromide (CsPbBr[subscript 3]), or lead sulfide (PbS) nanocrystals.

This paper introduces hands-on curricular modules integrated with research in atmospheric ice nucleation, which is an important phenomenon potentially influencing global climate change. The primary goal of this work is to promote meaningful laboratory exercises to enhance the competence of students in the fields of science, technology, engineering, and math (STEM) by applying an appropriate methodology to laboratory ice nucleation measurements. To achieve this goal, three laboratory modules were developed with 18 STEM interns and tested by 28 students in a classroom setting. Students were trained to experimentally simulate atmospheric ice nucleation and cloud droplet freezing. For practical training, this work utilized a simple freezing assay device called the West Texas Cryogenic Refrigerator Applied to Freezing Test (WT-CRAFT) system. More specifically, students were provided with hands-on lessons to calibrate WT-CRAFT with deionized water and apply analytical techniques to understand the physicochemical properties of bulk water and droplet freezing. All procedures to implement the developed modules were typewritten during this process, and shareable read-ahead exploration materials were developed and compiled as a curricular product. Additionally, students conducted complementary analyses to identify possible catalysts of heterogeneous freezing in the water. The water analyses included: pH, conductivity, surface tension, and electron microscopy-energy-dispersive X-ray spectroscopy. During the data and image analysis process, students learned how to analyze droplet freezing spectra as a function of temperature, screen and interpret the data, perform uncertainty analyses, and estimate ice nucleation efficiency using computer programs. Based on the formal program assessment of learning outcomes and direct (yet deidentified) student feedback, we broadly achieved our goals to (1) improve their problem-solving skills by combining multidisciplinary science and math skills and (2) disseminate data and results with variability and uncertainty. The developed modules can be applied at any institute to advance undergraduate and graduate curricula in environmental science.

The pharmaceutical and medicine manufacturing industry has become the largest industrial sector for the employment of chemists, indicating a need for experiments with a pharmaceutical sciences context in the undergraduate chemistry curriculum. In the pharmaceutical industry, testing drug dissolution is a key analytical task for solid oral dosage forms that is performed in different phases of drug development to test the release behavior of new formulations, ensure consistency between manufacturing lots, and help predict the "in vivo" absorption of the drug substance after administration. However, there are a limited number of laboratory experiments in dissolution testing developed for the undergraduate chemistry curriculum. To help students obtain hands-on experience in dissolution testing, a protocol has been developed for an undergraduate chemistry laboratory course for students to build a dissolution apparatus, monitor dissolution processes, model the dissolution to extract kinetic parameters, and evaluate the consistency between dissolution curves with FDA regulated methods. Students successfully collected dissolution curves and completed the modeling analysis with nonlinear least-squares fitting. The designed dissolution protocol has been evaluated to have consistency and reproducibility to be implemented in the undergraduate chemistry laboratory curriculum.

Machine learning (ML) is extensively applied in chemistry, particularly in vibrational spectroscopy. However, few teaching examples effectively demonstrate the capabilities of ML in classifying polymeric materials, exhibiting subtle spectral differences that elude visual discrimination. This study presents a teaching example specifically tailored for undergraduate students to acquire the skills necessary to employ ML models in the classification of infrared spectral data from different types of polyvinyl butyrals (PVBs). The course encompasses fundamental knowledge of PVB structure and synthesis, a comprehensive spectral analysis workflow for constructing classification models, specific data processing techniques, and practical implementation of a student-synthesized PVB product in a laboratory demonstration. Assessment of students' knowledge acquisition is conducted through assignments, and student attitudes toward this course via submitted self-reflection surveys are discussed. This study underscores the efficacy of classroom examples in developing students' abilities and fostering their interest in amalgamating chemistry and artificial intelligence. The knowledge and techniques acquired in this course hold practical implications for quality control, process monitoring, and material identification in industry.

Short chain fatty acids (SCFAs) are produced in the gut as a result of microbial action on ingested dietary fiber and have been associated with several health benefits. Herein an undergraduate student experiment that uses gas chromatography equipped with either a flame ionization detector or mass spectrometer for the analysis and quantitation of SCFAs in synthetic fecal material is described. The experiment provides students with valuable sample preparation and instrument operation skills and provides an opportunity for students to perform quantitative analysis using the method of internal standards. Subsequently, the experiment provides an opportunity for students to consolidate their learning of the key theoretical concepts including chromatographic separation by gas chromatography, and methods for confirming analyte identity using each detector type. Due to recent global interest in gut health, the experiment is topical and of interest to students. The experiment is designed for upper-division undergraduate analytical chemistry students.

The Beer-Lambert law is a fundamental relationship in chemistry that helps connect macroscopic experimental observations (i.e., the amount of light exiting a solution sample) to a symbolic model composed of system-level parameters (e.g., concentration values). Despite the wide use of the Beer-Lambert law in the undergraduate chemistry curriculum and its applicability to analytical techniques, students' use of the model is not commonly investigated. Specifically, no previous work has explored how students connect the Beer-Lambert law to absorption phenomena using submicroscopic-level reasoning, which is important for understanding light absorption at the particle level. The incorporation of visual-conceptual tools (such as animations and simulations) into instruction has been shown to be effective in conveying key points about particle-level reasoning and facilitating connections among the macroscopic, submicroscopic, and symbolic domains. This study evaluates the extent to which a previously reported simulation-based virtual laboratory activity (BLSim) is associated with students' use of particle-level models when explaining absorption phenomena. Two groups of analytical chemistry students completed a series of tasks that prompted them to construct explanations of absorption phenomena, with one group having completed the simulation-based activity prior to the assessment tasks. Student responses were coded using Johnstone's triad. When comparing work from the two student groups, chi-square tests revealed statistically significant associations (with approximately medium to large effect sizes) between students using the simulation and employing particle-level reasoning. That said, submicroscopic-level reasoning did not always provide more explanatory power to students' answers. Additionally, we observed the productive use of a variety of submicroscopic light-matter interaction models. We conjecture that engaging with BLSim provided new submicroscopic-level resources for students to leverage in explanations and predictions of absorption phenomena.

The laboratory is a complex environment where the three levels of the chemistry triplet coincide. As the laboratory environment places a large demand on the working memory of students, cognitive load theory can address overload which causes barriers to learning. Breaking down barriers requires iterative phases of analysis/exploration, design/construction and evaluation/reflection over multiple cycles which are the hallmarks of design-based research. In a complex setting, managing change and redressing teaching approaches can be difficult to navigate. Design-based research incorporates iterative phases in which theory informs decision making. This paper uses the context of a laboratory exercise of emission spectra to illustrate how the cognitive load theory can be used in tandem with design-based research to support student learning in the exercise. Using this approach, it was possible to show how barriers to student understanding, including task demands and conceptual demands were supported through proposed approaches focusing on extraneous, intrinsic and ultimately germane cognitive load.

Antioxidants are molecules that act against free radicals, and this effect can bring many benefits to health and society. Antioxidants can be found in various matrices of nature, such as fruits and plants. Some studies have shown that "Rhizophora mangle," a typical mangrove plant, is rich in antioxidants. People report its use for medicinal purposes, such as treating diabetes and high blood pressure. In Espírito Santo, Brazil, the bark extract of the plant is used as a waterproofing agent in the making of the capixaba clay pan, a cultural symbol of the state. Thus, this context was used as a reference for the application of chemical knowledge addressed in the teaching of Instrumental Analytical Chemistry. The participants were undergraduate chemistry students at the Federal University of Espírito Santo (Ufes). Two experiments were designed to be performed by groups of four to five students during 2-4 h laboratory classes. The students employed analytical techniques for spectrophotometric (FRAP, ferric reducing antioxidant power) and electrochemistry (CRAC, ceric reducing antioxidant capacity) determination of the total antioxidant capacity of "R. mangle" bark extracts. The experimental results indicated that the extracts of the plant have significant antioxidant capacity compared to trolox. By performing different extraction procedures and analytical techniques, students were able to compare, analyze, and evaluate strategies aimed at determining antioxidant capacity. The antioxidant capacity assays can be expanded to analyze other matrices of interest to professors and students.

The carbonyl group of an aldehyde or ketone reacts with different types of nucleophiles through a nucleophilic addition reaction. When the nucleophile is water, the product obtained is a "gem"-diol or geminal diol. This functionalization is unstable and quickly reverts to the parent carbonyl group. The chemistry of "gem"-diols is not usually covered in depth in organic chemistry courses. Herein, we propose a two-step activity to study the isolation of different "gem"-diols: an organic laboratory practice designed for undergraduate students combined with an in-class activity. The approach focuses on the study of heterocyclic compounds with aldehyde moieties using solution and solid-state nuclear magnetic resonance combined with X-ray crystallography.

Chemistry in water is an emerging field that fulfills the fifth principle of green chemistry: replacing toxic organic solvents with their benign counterparts. Although some pharmaceutical industries have developed and adopted chemistry in water, its implementation in teaching laboratories is still limited. Therefore, we have designed an experiment dedicated to the undergraduate curriculum covering sustainable, completely organic-solvent-free amide coupling, which is one of the most heavily used reactions in the pharmaceutical industry. The designed experiment aims to acquaint students with the 12 principles of green chemistry, inform them of the shortcomings of the traditional synthetic procedures of amide coupling, make them aware of waste generation from toxic organic solvents, and show them the effectiveness of water as a benign reaction medium. With the training throughout the lab sessions, students were taught micellar catalysis, NMR (nuclear magnetic resonance) spectroscopy, IR (infrared) spectroscopy, separation techniques, and safety data.

Spectroscopic methods of molecular structure identification and analysis constitute part of inorganic, organic, analytical, and physical chemistry in both undergraduate and postgraduate chemistry curricula. Despite the importance and complexity of the relevant concepts, it is only recently that studies on spectroscopy have started to appear in the education literature. These studies have focused on student interpretation of spectra. The purpose of this study was to deal with further fundamental issues underlying spectroscopy. We first present students' perceptions of their knowledge about various aspects of spectroscopy such as the extent of their understanding of the basic concepts of UV, IR, NMR, and MS. In addition, we probed students' declarative knowledge about basic concepts and features of spectroscopy. The results showed that mass spectrometry was perceived to be the least understood method, while IR was perceived to be the best understood. Students considered their ability to identify the spectroscopic method used for obtaining a spectrum to be relatively satisfactory, as also was, but to a lesser extent, their ability to extract information from the spectrum. Students rated their understanding of the differences among the four spectroscopic methods as moderate. Concerning students' declarative knowledge about basic concepts and features of spectroscopy, such as the physical meaning of "wavenumber" in IR spectroscopy and of "part per million" in NMR spectroscopy, "performing integration", and the "resolving power" of a spectrometer, the results were mostly poor. Interestingly, a clear difference was observed between performance on questions at high versus basic levels of declarative knowledge.

Plant-derived natural products are an important source of potential medicines and continue to have a major impact on the drug discovery process. Natural product discovery assignments provide an opportunity to present various experimental techniques to undergraduate students in introductory medicinal chemistry. This assignment was developed to serve as a meaningful hands-on exercise to introduce undergraduate Chemistry students to the common procedure in the early phase of drug discovery using inexpensive corn silk, in which the final year undergraduate student used Recycling Preparative High-Performance Liquid Chromatography to separate and purify steroids from corn silk. The student used advanced spectroscopic methods such as UV, IR, and one- and two-dimensional NMR to elucidate the structures of these steroids. The cytotoxic activity of these steroids was also evaluated and found to be non-cytotoxic to normal human MRC-5 cells at 60 µg/mL via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. With this assignment, students gain meaningful multidisciplinary hands-on exercises with the common procedure in the early stages of drug discovery and understand the process of isolating natural compounds that may lead to the development of new drugs.

The chemistry of 4d and 4f metals was investigated at the undergraduate level in an effort to incorporate f-element chemistry in the curriculum. This was accomplished through microwave-assisted synthesis of 1,10-phenanthroline (phen) coordination compounds [Eu(phen)(subscript 3)](PF[subscript 6])[subscript 3] and [Ru(phen)(subscript 3)](PF[subscript 6])[subscript 2], and embedding the coordination compounds in polystyrene (PS) beads. Through a combination of 1-D/2-D spectroscopic techniques, the metal-phen coordination compounds in solution and in the solid state were probed. It was validated that the strong interaction between the phen ligand and Ru[superscript 2+] is due to the diffuse nature of the 4d orbitals. The interaction resulted in a low energy MLCT band, which provides opportunities for excitation at lower energies using 4d metals. In contrast, the phen ligand and core Eu[superscript 3+] 4f orbitals exhibited a weak interaction. This was supported by variable-temperature NMR (VT-NMR) measurements, which revealed relatively well-separated proton resonances with minimal differences in chemical shifts for the phen ligand at 25°C and the [Eu(phen)(subscript 3)](PF[subscript 6])[subscript 3] compound at -42°C, indicating a weak Eu-N interaction. The weak interaction resulted in the formation of an aqua-containing complex in solution evidenced by emission lifetime measurements. Despite the weak interaction, selective excitation (via ligand [pi]-[pi]* versus direct f-f) of the Eu[superscript 3+] compound allowed for color tuning, leading to the generation of a cool white light. Electron probe microanalysis (EPMA) of the metal-embedded PS beads indicated relatively monodispersed distribution of the metal complexes in the polymer.

The dangers of organic dye pollutants and environmental pollution improvement through photocatalytic degradation are important courses in applied chemistry programs in universities. Zinc oxide (ZnO)-based nanomaterials are potent catalytic agents against organic dyes, but few experiments are available for students to understand their role and mechanism in class. Herein, we designed a comprehensive experiment across 24 class hours for undergraduates to investigate the photodegradation of colored organic dyes, including methylene blue, methyl orange, methyl violet, rhodamine B, basic fuchsin, and thymolphthalein, by a nanocomposite composed of ZnO-coated graphene oxide (ZnO/GO). This nanomaterial was prepared using a facile heating reflux method within 1 h. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were introduced to students to characterize the synthesized products. Students could observe the time- and dose-dependent degradation as well as the reusability of ZnO/GO. Additionally, the addition of t-butanol, benzoquinone, and triethanolamine, scavengers of hydroxyl radical ([superscript .]OH), superoxide anion ([superscript .]O[superscript 2-]), and hole (h[superscript +]), respectively, to the degradation system allowed them to master the underlying catalytic mechanism of ZnO/GO. This experiment improves students' understanding of the photocatalytic effect of ZnO nanomaterials and stimulates them to engage in the field of applied chemistry and thus is worth recommending to undergraduates.

A cornerstone activity in undergraduate organic laboratories revolves around students running instrumental analysis on their products and interpreting their spectra. They are left to link the theory they have learned in lecture to practical spectral interpretation. Students often memorize benchmark interpretations of peaks, such as the broad alcohol absorbance in infrared spectroscopy (IR). However, students often do not correlate the absorbance frequency to the actual vibrational mode. Given more nuanced spectra to interpret, like the difference between a hydrogen and a deuterium on an alcohol, students often miss the differences between the spectra. The GAMESS computational software package accessed through the Web interface ChemCompute is successfully used by students here to generate IR spectra of different isotopically labeled alcohols. This Web-based portal provides multiple benefits to the students: (1) The computational software is accessible through any browser on most common operating systems (including Chromebooks), (2) generating IR spectra for multiple products allows students to predict differences in spectra to compare to their actual IR data reinforcing prediction in the scientific method, and (3) the software links the differences in isotopes to structural vibrational modes visualized in the software allowing students to link theory to practice in spectral interpretation.

Computational and atmospheric chemistry are two important branches of contemporary chemistry. With the present topical nature of climate change and global warming, it is more crucial than ever that students are aware of and exposed to atmospheric chemistry, with an emphasis on how modeling may aid in understanding how atmospherically relevant chemical compounds interact with incoming solar radiation. Nonetheless, computational and atmospheric chemistry are under-represented in most undergraduate chemistry curricula. In this manuscript, we describe a simple and efficient method for simulating the electronic absorption spectral profiles of atmospherically relevant molecules that may be utilized in an undergraduate computer laboratory. The laboratory results give students hands-on experience in computational and atmospheric chemistry, as well as electronic absorption spectroscopy.

A major obstacle that teachers face when they begin their spectroscopy lessons is the lack of a spectrophotometer, mostly due to its relatively high cost. In the present study, the construction of a low-cost do-it-yourself type of instrument is reported. Its construction, as a part of a problem-based scenario, would also help students to enhance their chemical literacy. Moreover, the creation of a Jupyter Notebook called "Spectrophotometry" is also described. With this tool, students and teachers, within a few clicks, will derive absorption and fluorescence spectra and do kinetics studies without any difficulty and the need for time-consuming data postprocessing software. Finally, the views of a group of students on the construction and ease of use of our spectrophotometer are discussed in detail.

The pharmacologically active lignans sesamin and sesamolin are minor components of sesame oil and ingredients in OTC dietary supplement capsules. We report an introductory undergraduate organic laboratory experiment combining natural product isolation and spectral analysis in which students isolate a mixture of sesamin and sesamolin by either (1) dry column vacuum chromatography (a convenient alternative to flash column chromatography) of commercial sesame oil using an apparatus constructed from common laboratory glassware or by (2) solid-liquid extraction of commercial sesame seed lignan dietary supplement capsules. Two recrystallizations from methanol remove most of the sesamolin to afford crystalline sesamin, which, due to its 2-fold rotational symmetry, students can easily identify and characterize by NMR. During a second laboratory period, students perform a 5 min, test tube-scale reaction of sesamin with catalytic BF[subscript 3]:OEt[subscript 2] to promote its epimerization to episesamin, a diastereomer of sesamin lacking rotational symmetry, and the sesamin/episesamin ratio in the resulting product mixture is established by [superscript 1]H NMR integration. Students are asked to propose a mechanism for this epimerization based on their knowledge of the reactivity of benzyl ethers under acidic conditions.

A comprehensive laboratory-style teaching activity involving the synthesis, characterization, and analysis of structure-activity relationships of metal-organic framework (MOF) nanozymes was developed specifically for undergraduates at Tianjin University. The students acquired familiarity with the general approach in synthesizing MOFs by solvothermal method using substituted MIL-101­(Fe)-X (MIL is an acronym for Materials of Institute Lavoisier). Several modern characterization methods were taught, including powder X-ray diffraction and fluorescence spectroscopy for assessing MIL-101­(Fe)-X crystal structures and superoxide dismutase (SOD)-like activities. In particular, students were guided by the instructor to investigate the relationship between structural differences in MOFs caused by ligand changes and their SOD-like activities. The Hammett relationships were later demonstrated to be an accurate method of quantifying structure-activity relationships of MIL-101­(Fe)-Xnanozymes. By participating in this laboratory experience, students are able to improve their scientific thinking, practical abilities, and teamwork. Additionally, a fundamental principle of material design can be conveyed to undergraduates based on the structure-activity relationship, thereby deepening their understanding of nanozymes and the course's content.

The methodology and mathematical treatment of several classic multivariate methods for the analysis of spectroscopic data is demonstrated in a straightforward way that can be used as a basis for teaching an undergraduate introductory course on chemometric analysis. The multivariate techniques of classical least-squares (CLS), principal component regression (PCR), and partial least-squares (PLS), as well as the univariate Beer's law method have been described and compared, building students' understanding by starting with the univariate method and progressing step by step into the multivariate methods. Equations for the production of regression vectors from training set spectral data are described and their use demonstrated for the prediction of constituent concentrations on a separate validation set of spectra. Extreme care is taken to ensure consistency in variable formatting of data matrices. This provides a key foundation to understand how spectral data are manipulated using these different mathematical approaches for building quantitative regression models. Each method is applied to a real-world data set, and the results are discussed to show students the types of information that can be gleaned from each method. A training set comprising 20 infrared absorbance spectra containing 3 constituents (benzene, polystyrene, and gasoline) of known composition are used to demonstrate the matrix operations for each regression method. A separate set of 12 real-world napalm samples (containing benzene, polystyrene, and gasoline) are used as a validation set to demonstrate the ability to utilize the regression models on an unknown data set. A toolbox (PNNL Chemometric Toolbox) written in MATLAB language is supplied in the Supporting Information and can be used as a companion for understanding the development and deployment of the chemometric algorithms described in this paper. The data sets of the infrared spectra are also supplied, allowing users to build and inspect the chemometric models on their own. Finally, the Toolbox includes scripts to assist users in loading their own data sets into MATLAB and performing CLS, PCR, and PLS on their data.

Here we showcase an undergraduate teaching laboratory in which students synthesize and characterize colloidal nanoparticles of organic semiconductors and assess their suitability for applications in printed electronics such as solar cells and bioelectronics. Scanning electron microscopy, UV-visible spectroscopy, and photoluminescence spectroscopy are used to characterize the nanoparticles, and students learn how to match electron donating (p-type) and electron accepting (n-type) materials based on the literature material characteristics: HOMO, LUMO, and charge carrier mobility. This teaching laboratory exercise was developed as part of the University of Newcastle Centre for Organic Electronics Spring School program and includes data from a cohort of 44 undergraduate student participants. The teaching laboratory exercise is applicable to undergraduate students in multiple disciplines, including physical chemistry, chemical engineering, materials science, and physics, and can be altered to suit time, level of experience, and instrumentation availability. The exercise utilizes a post-practical quiz to provide feedback and assess embedded knowledge. The student cohort responded well to the post-practical quiz, for example, 94% correctly identified the purpose of synthesizing nanoparticles of organic semiconductors for printed electronics applications being eco-friendly high-throughput processing benefits as well as the ability to nanostructure the photoactive layer to optimize exciton dissociation. This Laboratory Experiment also provides a set of Student Learning Objectives (LOs) and a detailed account of observations/outcomes in attaining these LOs for the student cohort at the Spring School program. This experiment is an introductory lesson in colloidal nanomaterials and gives students exposure to the chemistry, physics, and materials science concepts of organic electronics.

The pharmaceutical industry relies heavily on analytical techniques for identifying and characterizing drug compounds. In this experiment, undergraduate pharmacy students explored the applications of near-infrared spectroscopy for pharmaceutical analysis and its potential for identifying patterns and relationships among pharmaceutical samples. In addition, they were introduced to the chemometrics field using classical pretreatment and data exploration methods. To reduce the need for expensive instrumental equipment, we have developed a small and affordable device based on the DLP NIRscan Nano EVM by Texas Instruments using free software solutions and a 3D-printed case for Raspberry Pi single-board computers. The goal of the experiment was to guide students through all the necessary steps for measuring and analyzing samples using NIR spectroscopy and to encourage their learning through the application of mathematical methods in a defined laboratory setting.

A Fourier transform infrared (FTIR) experiment appropriate for an upper-level undergraduate laboratory such as chemical instrumentation is described. Students collect FTIR spectra of four protio-solvents and their deuterated analogues. In addition to qualitatively observing C-H and O-H peaks shift to lower energy upon deuteration, students apply a simple harmonic oscillator model to predict the magnitude of the shifts and gain an understanding of the relationship between reduced mass and vibrational frequencies. Vibrational calculations are then performed to corroborate the experimental results and allow students to visualize the normal modes involved via animations of the vibrations. This experiment is suitable to be used as either an in-person or online laboratory.

Chemistry undergraduate curricula typically place Nuclear Magnetic Resonance (NMR) lectures under either Organic Chemistry or Spectroscopy courses, aiming for students to acquire basic knowledge for the determination of the structure of simple organic compounds. On the other hand, regarding laboratory practice, NMR is frequently disregarded by Analytical Chemistry or Instrumental Analysis courses, where chromatographic and spectrophotometric methods are the primary analytical techniques taught for the detection and quantification of analytes. However, in recent years, quantitative NMR (qNMR) has been increasingly used for the analysis of natural products, drugs, and foods. Consequently, it would seem advisable to encourage a more active inclusion of NMR in Chemistry courses. One step in that direction is to develop teaching strategies for the laboratory practice, focused on qNMR, that can be featured in the curricula of instrumental analysis courses, to provide students with the essential skills for qNMR practice. Following this logic, an experimental procedure for quantifying caffeine in energy drinks using NMR as an analytical technique, designed to be carried out by students of Analytical Chemistry and Instrumental Analysis courses of chemistry majors, is described below. The pedagogical coverage of this teaching activity, intended for Instrumental Analysis or Analytical Chemistry laboratory courses, includes topics such as solutions and sample preparation with deuterated solvents, NMR instrumentation, NMR data analysis for signal assignment and integration, qNMR concepts, and validation parameters.

It is crucial nowadays to predict in a fast and simple manner physical-chemical behaviors like, the size-dependent optical properties of gold nanospheres (Au NSs). The idea behind this experiment is trying to replace (as much as possible) robust and expensive microscopy techniques with UV-vis spectrophotometry and friendly simulations. Students chemically synthesized [approximately]4 and [approximately]15 nm diameter NSs and grew larger ones to [approximately]32, [approximately]50, and [approximately]70 nm diameter using the previously obtained [approximately]15 nm as seeds. They characterized them via UV-vis spectroscopy to ultimately compare the spectra with user-friendly software including MiePlot, nanoHUB.org, and the Amendola algorithm (Wolfram Mathematica). For Au NSs [less than or equal to]25 nm diam., the experimental UV-vis spectra fitted very well with the Amendola algorithm to determine the size. For Au NSs >25 nm diam., the experiment exhibited larger Au NSs than expected as noticed by the systematic red shift of the plasmon band with respect to the simulated one. A SEM image confirmed larger Au NSs; therefore, students were challenged to determine the source of discrepancy between experimental and simulated UV-vis spectra, which was later attributed to the aging of the Au NSs seeds. This experiment demonstrates an easy way to accurately determine the nanoparticle size while exploring and solving potential issues that students may face during the chemical synthesis and simulations.

This laboratory experiment consists of the synthesis of two series of alkaline-earth titanates (calcium-strontium and strontium-barium)to corroborate Vegard's law by obtaining their X-ray diffraction patterns and plotting the lattice parameter versus mole fraction of both cations. This experiment allows students to understand the key concepts in the solid state chemistry of a lattice parameter, a cubic Bravais network, a perovskite type structure, substitutional solid solutions, Vegard's law and its deviations, Miller indices, and X-ray diffraction principles. In addition, it gives students the opportunity to acquire technical skills in ceramic synthesis and X-ray diffraction pattern interpretation.

This laboratory exercise integrates chemistry and biology concepts to give third/fourth-year undergraduate students an opportunity to apply knowledge from different subject areas to address a real-world biomedical issue such as pathogen inhibition using composite materials. It involves the preparation of a bacteria-derived cellulosic biopolymer through microbial cultivation, impregnation of the bacterial cellulose(BC) with silver nanoparticles (AgNPs), followed by the analysis of the materials and the antimicrobial properties of the biomaterial-AgNPs composites. The methods are relatively simple and use inexpensive chemicals. A Tollens type approach is adopted to produce silver nanoparticles-bacterial cellulose (AgNPs-BC) composites by the reduction of [Ag­(NH[subscript 3])[subscript 2]]+ complex embedded in the cellulose matrix. The samples were dried by two different methods: freeze-drying or vacuum-drying. The dried AgNPs-BC films were evaluated for antimicrobial properties against a test organism, in this example, "Pseudomonas aeruginosa", a Gram-negative biosafety containment level 2 (BSL 2) bacterium, using an agar diffusion test. For additional flexibility and customization, options for dividing the chemistry/biology content of this laboratory into smaller units with an emphasis on characterization techniques of nanomaterials for chemistry majors are also discussed.

A straightforward protocol for the preparation of the colorful and air-stable diphenyl ditelluride is described. In one laboratory session, students isolate their product and characterize it via melting point determination, mass spectrometry, and NMR spectroscopy ([superscript 1]H, [superscript 13]C­{[superscript 1]H}, and [superscript 125]Te­{[superscript 1]H}). The alternative application of a Grignard reagent serves as a bridge between common organic laboratory experiences and this exercise. Students have the opportunity to see the advantages and disadvantages of the assortment of characterization techniques and, for MS and NMR, the distinctness of their application specifically to inorganic compounds. Analysis of single crystal X-ray diffraction data and molecular modeling results of Ph[subscript 2]Te[subscript 2] and its lighter congeners (Ph[subscript 2]E[subscript 2], E = O-Se)provide students with a data-supported understanding of the inert pair effect.

A laboratory experiment in which [superscript 1]H NMR and UV-vis spectroscopies are applied to probe the temperature dependence of a monomer-dimer equilibrium involving a cyclopentadienone derivative is described and discussed. Details of the data analysis for extraction of equilibrium constants from the raw experimental data from both techniques are provided, leading to the determination of thermodynamic parameters ([delta][subscript r]H° and [delta][subscript r]S°) via van't Hoff analysis. Fully analyzed datasets are provided in the Supporting Information to aid adaptation of the experiment or its use as a data analysis activity.

The aroma volatile compounds in tomatoes are strongly linked to taste and flavor. Commercial tomato varieties, however, generally lack flavor. Tomato breeding programs have therefore started to focus on increasing the flavor-enhancing volatiles, which can be more easily altered than the sugar content. Analytical efforts that identify key flavor volatiles are therefore an important part of tomato improvement programs. Based on this real-world goal, an upper-level undergraduate analytical laboratory exercise has been developed that utilizes solid-phase microextraction (SPME) and gas chromatography-mass spectrometry to characterize tomato volatiles. Students adsorb volatile organic compounds (VOCs) and a spiked internal standard onto SPME fibers, and these volatiles are thermally desorbed in a gas chromatograph--mass spectrometer (GC-MS) for identification and quantification. VOCs from hybrid heirloom tomatoes (open-pollinated, older cultivars not bred for industrial agriculture) and store-bought tomatoes are compared and normalized to the internal standard, and students determine which volatiles contribute to positive (and negative) taste perceptions. The laboratory exercise has been employed successfully in our Instrumental Analysis course over three years. Using previously obtained data, the exercise was also modified for remote (Zoom) laboratory learning. The experimental protocol is robust with few technical issues, and students produce replicable data. Because students can relate easily to the subject matter of the research, engagement is high. A large, complex data set is produced in this exercise, and students learn to draw conclusions from this data set that mimic real-world, authentic research.

This exercise encompassed the construction and use of a microcontroller-based laser refractometer. The instrument, which does not require a high skill level to build, primarily consisted of a line laser, optical sensor, several 3-D printed parts and printed circuit boards, and a microcontroller development board. Construction and testing of the device occurred in upper division analytical chemistry courses, either quantitative analysis or instrumental methods, and data analysis of real-world samples took place in the general chemistry laboratory. Open-source software was used to (a) communicate between a laptop and microcontroller and (b) record data in real-time directly to an Excel spreadsheet utilizing visual Basic for applications (VBA) an event driven programming language that is part of Microsoft Office applications. In addition to collecting the data, general chemistry students used Excel to generate a calibration curve and determine the concentration of ethylene glycol in an antifreeze sample. Student engagement was assessed using a Likert-type survey, and the results were analyzed using statistical methods. Laboratory reports and a postlab quiz were used to assess student learning outcomes.

The understanding of analytical chemistry and its application in different areas of life science is something that should be encouraged for students studying chemistry, and also something that appeals to many students. Life science includes a vast variety of areas, out of which some are more easily approached in student projects. The chemical communication between organisms, such as plants, as described in chemical ecology is one example. It is therefore beneficial to offer students inquiry-based project work that allows them to explore, and gain a deeper understanding of, this discipline within the grand context that is chemistry. Hence, the present work describes the application of analytical chemistry using gas chromatography--mass spectrometry, including sample preparation for the study of chemical inhibitory (allelopathic) properties of compounds found in the plant "Aegopodium podagraria." The questions posed to the students performing this project work were "What compounds can be found in the extracts of the plant?", "Are the extracts allelopathic?", and "Can you determine which compounds contribute to the possible allelopathic properties?". The reported results indicate that the extracts might have allelopathic properties and showed that the extracts contained compounds such as a-pinene and ß-caryophyllene. The identified terpenes were shown to have minor allelopathic properties by themselves but displayed an impact on the germination of seeds and length of the sprouts when applied as a blend. This project, and its results, proposes a framework for investigation of other plants and can be adapted to suit students at different academic levels.

Nuclear magnetic resonance (NMR) spectroscopy is a very powerful analytical method that has found many applications in physics, chemistry, biology, and medicine. It is an indispensable tool particularly for synthetic chemists because it can be used for a rapid elucidation of the structures of organic compounds. For this reason, NMR spectral interpretation is a part of the core knowledge of all chemistry students, taught to them from the first years of their undergraduate studies. However, NMR spectral interpretation skills can only be learned by experience. We present a new educational website that includes more than 160 NMR spectral assignments measured for real samples. Each assignment contains NMR spectra of an unknown compound, with the task for the students being to determine its structure. Basic assignments contain only one-dimensional [superscript 1]H and [superscript 13]C NMR spectra; advanced assignments also offer two-dimensional correlation spectra. The web application is enriched with an interactive chemical structure drawing tool, which gives the users immediate feedback about their proposed structures. The presented assignments are graded according to difficulty to keep both beginners and advanced students motivated. The web page will be continuously updated with new spectral problems.

Ultrafast laser spectroscopy is a valuable and increasingly accessible technique for studies of rapid chemical reactions. Critical to ultrafast spectroscopy is the concept of mode locking, a technique that enables a fixed phase relationship between laser modes, resulting in laser pulses with very short duration (in the fs or ps range). Despite the increasing importance of ultrafast lasers in chemistry, the introduction of key concepts behind their operation into the undergraduate and graduate chemistry coursework has been limited. To help the incorporation of these topics into chemistry courses, we report here a hands-on activity that helps students develop an intuitive understanding of the factors that impact electromagnetic wave evolution in optical cavities and the process of mode locking. We first provide the theoretical background by introducing cavity modes and contrasting them with well-known propagating electromagnetic waves. We then explore what happens when modes are added and how the relative phase between the modes affects their behavior. In the second section of this report, three teaching modules are provided, along with associated MATLAB codes and animated images, that can be used in the classroom to introduce concepts of cavity modes and mode locking. These teaching modules start by contrasting propagating electromagnetic waves with cavity modes and then illustrate what happens when multiple modes are present in the cavity and how the relative phase between the modes affects the overall electromagnetic field in the cavity.

A class of 18 students attending the last year of an Italian high school was divided into groups and performed the extraction of pigments contained in hibiscus tea. Each group worked at a different temperature and carried out multiple extractions using distilled water as a solvent. By means of UV-vis spectroscopy it was possible to determine the yield of each individual extraction and then to study the effect of temperature on the extraction itself. The method is easy to implement, it does not require the use of hazardous reagents or special safety precautions, and it is very cheap. The laboratory part was carried out in 3 h time, while the analysis and data processing took about 4 h. On an educational level, the students learned to process and analyze large amounts of data, and they became familiar with the UV-vis spectrophotometer and eventually had to solve the problems independently.

We report here a successful adaptation of lab videos used during remote instruction to a kinetics experiment reported in this Journal in 2007. In the in-person lab, students now record their rate data on their cell phone cameras and then collect their data from the videos for their postlab reports; previously, they acquired the data in real time from the spectrophotometer reading and a stopwatch. We have found that increasing the concentration of the bleach, which speeds up the rate faster than data can be directly recorded in real time (1) does not affect the reaction order and (2) decreases lab time.

In both general chemistry and analytical chemistry courses, students are introduced to the concept of predominant species in solution when discussing acid/base chemistry. Speciation diagrams are often used to illustrate the concept and predict the relative abundance of species in solution. Herein, we describe a laboratory experiment for an undergraduate analytical chemistry course, in which students directly measure the speciation diagram and compare it to the diagram calculated using equations they derive in lectures. In this laboratory experiment, students prepare solutions of fixed pH in the pH range 0-14 and use them to measure the speciation diagram of thymol blue with UV-vis spectrophotometry. After collecting the absorbance spectra of all the solutions, students perform a series of data processing steps to derive the speciation diagram of thymol blue from the experimental data and compare it to the calculated diagram. Finally, students use the speciation diagram to corroborate the expected pH ranges, in which the three forms of thymol blue are predominant species. This experiment provides students with a hands-on experience with buffer preparation, enables a straightforward measurement of the speciation of different forms of a diprotic acid, and helps them visualize the concept of predominant species in solution.

The optical spectrometer is a widely established and widely used scientific instrument for analyzing biochemical samples. However, it is expensive, bulky, and requires an external power source and a computer to operate, which makes it difficult to use in resource-limited countries and in remote locations. Advancement in smartphone technology has led to the development of portable, low-cost smartphone-based spectrometers. However, the lack of smartphone-based software and automatic wavelength calibration results in irrelevant workloads for students within the time limit of the course. In addition, most smartphone spectrometers are only able to capture images. As a result, a computer becomes an essential tool for the student to process and analyze the sample spectrum. Unlike many other smartphone-based spectrometers, our developed device also provides a smartphone application for both Android and iOS platforms. Thus, measurement data and data plots are transferrable among smartphones and computers. In addition, the wavelength calibration is carried out automatically using an embedded reference white light LED by the application. Furthermore, the provided 3D-printedparts, part lists, and circuit board are included with an example of an iPhone 7 mount, as well as their assembly instructions. Our developed device features a sufficiently quantitative measurement for wavelength ranges from 411.2 to 700 nm. For the spectral resolution, our device achieved resolutions of 9.8, 13.4, and 21.7 nm at wavelengths of 405, 532, and 650 nm, respectively, when evaluated with an iPhone7.

The dissolution of cobalt­(II) chloride in an appropriate binary alcohol solvent yields an equilibrium mixture, consisting of the differently colored octahedral (pink in color) and tetrahedral (blue in color) cobalt­(II) coordination complexes, which can exhibit a brilliant and reversible pink-to-blue color transition over a ~10 °C window - i.e., function as a thermochromic thermometer where the dynamic equilibrium is described by CoCl[subscript 2](R[subscript 1]OH)[subscript 4]+2R[subscript 2]OH?CoCl[subscript 2](R[subscript 2]OH)[subscript 2]+4R[subscript 1]OH. In this experiment, students are challenged to exploit the principles of equilibrium in order to exhibit control over the chemical system and design, model, and implement a thermochromic thermometer which, when correctly prepared, exhibits a specifically targeted composition and color at a unique temperature assigned to each student. By employing fundamental principles of physical chemistry in conjunction with spectrophotometric analysis, students quantify pertinent thermodynamic parameters for the chemical system, and then use them to predictively model/calculate (via Excel) the exact initial composition required to enable the specifically desired equilibrium composition and color to emerge at precisely the target temperature. Completely directed by their modeled prescriptions, students then validate their theoretical predictions by implementing the functional thermochromic thermometer in the laboratory.

Stereoselective reduction of ketones to alcohols using baker's yeast is a classic experiment in the undergraduate laboratory. Here we illustrate the reduction of racemic ethyl 2-fluoro-3-oxobutanoate to the corresponding alcohol using a set of four commercially available ketoreductases (KREDs). The reaction sets two stereocenters with four stereoisomers possible, with different KREDs selecting for different stereoisomers. Products are characterized by [superscript 1]H and [superscript 19]F NMR spectroscopy to establish diastereomeric and enantiomeric excess. Students learn about dynamic reductive kinetic resolution (DYRKR) and perform NMR Mosher ester analysis for stereochemical assignments.

Ultrafast laser pump-probe spectroscopy is an important and growing field of physical chemistry that allows the measurement of chemical dynamics on their natural time scales, but undergraduate laboratory courses lack examples of such spectroscopy and the interpretation of the dynamics that occur. Here we develop and implement an ultrafast pump-probe spectroscopy experiment for the undergraduate physical chemistry laboratory course at the University of California Berkeley. The goal of the experiment is to expose students to concepts in solid-state chemistry and ultrafast spectroscopy via classic coherent phonon dynamics principles developed by researchers over multiple decades. The experiment utilizes a modern high-repetition-rate 800 nm femtosecond Ti:sapphire laser, split pulses with a variable time delay, and sensitive detection of transient reflectivity signals using the lock-in technique. The experiment involves minimal intervention from students and is therefore easy and safe to implement in the laboratory. Students first perform an intensity autocorrelation measurement on the femtosecond laser pulses to obtain their temporal duration. Then, students measure the pump-probe reflectivity of a single-crystal antimony sample to determine the period of coherent phonon oscillations initiated by an ultrafast pulse excitation, which is analyzed by fitting to a sine wave. Students who completed the experiment in-person obtained good experimental results, and students who took the course remotely due to the COVID-19 pandemic were provided with the data they would have obtained during the experiment to analyze. Evaluation of student written and oral reports reveals that the learning goals were met, and that students gained an appreciation for the field of ultrafast laser-induced chemistry.