In light of COVID-19 in spring 2020, we developed a simple and versatile inquiry-based, laboratory-style active learning colorimetry experiment amenable to at-home quantitative analysis. In this experiment, students acquire an external calibration method using aqueous solutions of a self-selected chromophoric analyte from household products using a smartphone camera and RGB image analysis. We report typical student-obtained results for a 5point external calibration method using RGB image analysis and solutions prepared with green food colorant and blue food colorant. Solutions were prepared using common kitchen measuring tools, glass drinking cups served as sample cells or cuvettes, images were acquired with a smartphone camera, and image analyses were conducted using RGB analysis software. Results show analytical data can be readily obtained for both colorimetric and absorbance-based analyses. Experientially, results show that throughout method development students are challenged with various quantitative analysis learning objectives, including basic concepts about light−matter interactions, analytical solution preparation, chemical concentrations, unit analysis, significant figures, statistical analysis, and analytical figures of merit (i.e., method robustness, linearity, and sensitivity, etc.). Furthermore, by bringing chemistry into the home, students are challenged to be creative and access a wide range of problem-solving and critical thinking skills, some of which may not be exercised in traditional laboratory experiments and projects.

The catalytic hydrogenation of alkenes and alkynes is an important part of the undergraduate chemistry curriculum and is a fundamental process in chemical industry. Inquiry-based laboratory activities are presented that investigate the hydrogenation of alkynes on a nanoparticle palladium surface to form alkenes, which go on to form alkanes. Alkyne hydrogenation using H2 and/or D2 proceeds via a vinyl–palladium intermediate to form a π-bonded alkene–Pd species that can desorb or remain on the palladium surface and undergo further hydrogenation via the Horiuti–Polanyi mechanism, associated with extensive deuterium–hydrogen exchange. Central to the experiments is an inexpensive, easy-to-build glass tube containing palladium nanoparticles on alumina beads that can be used indefinitely. A total of seven inquiry-based questions are discussed regarding hydrogenation of alkynes. A similar number of open questions are discussed for further investigations by interested persons. These activities are suitable as guided research projects for science majors. Each experiment is performed by groups of two or three students in about an hour including analysis by mass spectrometry. An additional hour is allowed for student analysis and discussion of the mass spectral results, writeup, and future planning followed by about 30 min with the mentor for group presentation and discussion of the results. Results often lead to additional questions, either for clarification or for new exploration and form the basis for inquiry-based learning and problem-solving.

Cyclopropane can be hydrogenated to produce propane under moderately high temperatures (∼175 °C). Using a nanoparticle palladium catalyst, undergraduate students can explore the reaction and draw conclusions regarding the conditions for reaction. When deuterium is used, conclusions pertaining to the reaction mechanism are possible. The full complexity of the hydrogen−deuterium exchange equilibrium on the metal surface is indicated by the observation of all nine possible hydrogen−deuterium isotopologues, propane-d x (x = 0− 8), as products. To think about the reaction mechanism, the unusual bonding in cyclopropane and its interactions with a metal surface are considered. Differences between cyclopropane and propane in terms of their physical and chemical properties are discussed. The use of this activity as a multisemester research project across all levels of undergraduate students is discussed in terms of logistics, expectations, and outcomes. The catalyst tube consists of nanoparticle palladium beads (0.5%) on alumina, is inexpensive and easy to construct, and lasts indefinitely. Product analysis is by mass spectrometry and 1 H NMR spectroscopy. Suggestions are provided for undergraduate exploration and inquiry-based research activities.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb), is one of the leading causes of death in developing countries. Non-tuberculous mycobacteria (NTM) infections are rising and prey upon patients with structural lung diseases such as chronic obstructive pulmonary disease (COPD) and cystic fibrosis. All mycobacterial infections require lengthy treatment regimens with undesirable side effects. Therefore, new antimycobacterial compounds with novel mechanisms of action are urgently needed. Published indole-2-carboxamides (IC) with suggested inhibition of the essential transporter MmpL3 showed good potency against whole-cell M.tb, yet had poor aqueous solubility. This project focused on retaining the required MmpL3 inhibitory pharmacophore and increasing the molecular heteroatom percentage by reducing lipophilic atoms. We evaluated pyrrole, mandelic acid, imidazole, and acetamide functional groups coupled to lipophilic head groups, where lead acetamide-based compounds maintained high potency against mycobacterial pathogens, had improved in vitro ADME profiles over their indole-2-carboxamide analogs, were non-cytotoxic, and were determined to be MmpL3 inhibitors.