Using Flipped Classroom Modules to Facilitate Higher Order Learning in Undergraduate Organic Chemistry.

In an ongoing effort to incorporate active learning and promote higher order learning outcomes in undergraduate organic chemistry, a hybrid ("flipped") classroom structure has been used to facilitate a series of collaborative activities in the first two courses of the lower division organic chemistry sequence. An observational study of seven classes over a five-year period reveals there is a strong correlation between performance on the in-class activities and performance on the final exam across all classes; however, a significant number of students in these courses continue to struggle on both the in-class activities and final exam. The Activity Engagement Survey (AcES) was administered in the most recent course offering included in this study, and these preliminary data suggest that students who achieved lower scores on the in-class activities had lower levels of emotional and behavioral/cognitive engagement and were less likely to work in collaborative groups.

A Self-Assembled Cage with Endohedral Acid Groups both Catalyzes Substitution Reactions and Controls Their Molecularity.

A self-assembled Fe L cage complex internally decorated with acid functions is capable of accelerating the thioetherification of activated alcohols, ethers and amines by up to 1000-fold. No product inhibition is seen, and effective supramolecular catalysis can occur with as little as 5 % cage. The substrates are bound in the host with up to micromolar affinities, whereas the products show binding that is an order of magnitude weaker.

Small Structural Variations Have Large Effects on the Assembly Properties and Spin State of Room Temperature High Spin Fe(II) Iminopyridine Cages.

Small changes in steric bulk at the terminus of bis-iminopyridine ligands can effect large changes in the spin state of self-assembled Fe(II)-iminopyridine cage complexes. If the added bulk is properly matched with ligands that are either sufficiently flexible to allow twisted octahedral geometries at the Fe centers or can assemble with unusual mer configurations at the metals, room temperature high spin Fe(II) cages can be synthesized. These complexes maintain their high spin state in solution at low temperatures and have been characterized by X-ray crystallographic and computational methods.

Tandem Reactivity of a Self-Assembled Cage Catalyst with Endohedral Acid Groups.

Self-assembly of a carboxylic acid-containing ligand into an FeL iminopyridine cage allows endohedral positioning of the acid groups while maintaining a robust cage structure. The cage is an effective supramolecular catalyst, providing up to 1000-fold rate enhancement of acetal solvolysis. This enhanced reactivity allows a tandem deprotection/cage-to-cage interconversion that cannot be achieved with other acid catalysts.

Electronic Effects on Narcissistic Self-Sorting in Multicomponent Self-Assembly of Fe-Iminopyridine meso-Helicates.

Small changes in the electron donating ability of coordinating groups have substantial effects on the multicomponent self-assembly of Fe (II)-iminopyridine-based meso-helicate complexes. Both the nature of the internal diamine core and the terminal formylpyridine reactants control the rate of the assembly process, the thermodynamic favorability of the meso-helicate products, and the selective incorporation of different aldehyde termini into the assembly. Steric congestion at the coordinating ligands can prevent assembly altogether, and favorable incorporation of electron-rich aldehyde termini is observed, even though the rate of reaction is accelerated by the use of electron-poor aldehyde reactants.