Through a close examination of the intermolecular interactions of rubrene (1a) and select derivatives (1b− 1p), a clearer understanding of why certain fluorinated rubrene derivatives pack with planar tetracene backbones has been achieved. In this study we synthesized, crystallized, and determined the packing structure of new rubrene derivatives (1h−p). Previously, we proposed that introducing electronwithdrawing CF 3 substituents induced planarity by reducing intramolecular repulsion between the peripheral aryl groups (1e−g). However, we found that in most cases, further increasing the fluorine content of rubrene lead to twisted tetracene backbones in the solid state. To understand how rubrene (1a) and its derivatives (1b−p) pack in the solid state, we (re)examined the crystal structures through a systematic study of the close contacts. We found that planar tetracene cores occur when close contacts organize to produce an S symmetry element about a given rubrene molecule. We report the first instance of rubrene derivatives (1l and 1n) that pack in a two-dimensional brick motif. The prospects for new rubrene derivatives in semiconductors were estimated by calculating the reorganization energies of the monomers and transfer integrals of the dimers we observed. Our work allows for the rational design and improved crystal engineering of new rubrene derivatives.

The mechanism maps that guide student instruction in organic chemistry curricula are structural representations of bond-breaking and bond-making events that transform a reactant into a product. For students, these pathways represented by electron pushing formalism (EPF) can be challenging to navigate. For instructors, providing formative feedback to students to support their learning of the EPF arrow system is difficult to provide in a timely manner. The Mechanisms App (“the App”) was developed as a method for students to explore the electron movement of organic chemistry through a touch screen interface of a smart phone or tablet with real-time feedback of these moves. In this paper, the pedagogical content of the App and its backend system is described. This system produces a graphical record of a user’s move within the App and is called a decision tree. A study of students’ use of the App in two different modes was devised to understand whether the in-app experience can facilitate a hypothesis-driven approach to learning EPF. Examples of classroom implementation for the App in a variety of institutions and future research are also described.

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As digital educational media use becomes more widespread, an opportunity exists to develop new methods to present abstract ideas to provide a more meaningful learning experience. Drawing from psychology and dynamic visualization research, new interactive tools can be thoughtfully designed but it is also necessary to establish how these media are used and to study the effects the new interactive tools have on concept understanding. In this technology report, we present the Hybridization Explorer, a web-based interactive learning tool for manipulating and experimenting with hybridization concepts. The explorer has three modes of use to explore both the combination of atomic orbitals, and the visual representation of both atomic and hybrid orbitals and corresponding bond formation. Case studies from an undergraduate-and graduate-level demonstration of the explorer are described. Finally, self-reported student confidence levels on solving hybridization questions both before and after use of the explorer are analyzed and discussed.

<p>This paper details the results of a qualitative study examining the reasoning students use to solve common hybridization theory assessment questions and their mental images of hybrid and atomic orbitals. The data were collected through think-aloud interviews as students worked through a five-question questionnaire. Prior to recruitment, the study was deemed to be exempt from IRB review by Sterling IRB. Prior to start of interviews participants provided verbal consent. The resulting transcripts and answers were analyzed following the practices of grounded theory and constant comparative analysis. Coding schemes can be found in the Supplementary Information section. Results, conclusions, and implications for teaching are presented in the manuscript.</p>