Hydrogen-bonded complexes of bromocyclopropane with the strong bases ammonia and trimethylamine have been isolated and characterized for the first time in argon matrices at 16 K. Coordination of the proton adjacent to the Br substituent on the cyclopropane ring to the nitrogen of the base was evidenced by distinct blue shifts of the C−H(Br) bending modes in the infrared spectrum. These shifts (∼12 cm-1 for the in-plane bend and ∼6 cm-1 for the out-of-plane bend) are much smaller than those observed for alkenes and alkynes, suggesting a distinct but extremely weak interaction. Ab initio calculations yield an essentially linear BrC−H···NH3 hydrogen bond with a C−H···N distance of 2.301 Å and a hydrogen bond energy of 2.35 kcal/mol, thus supporting that this hydrogen bond is one of the weakest observed thus far in a matrix. This study represents the first example of a (substituted) cyclopropane acting as a proton donor and only the second example of an alkane taking part in a C−H···N hydrogen bond.

Hydrogen-bonded complexes of cyclopentadiene with the strong bases ammonia, trimethylamine, and dimethyl ether have been isolated and characterized for the first time in argon matrices at 16 K. Coordination of the acidic alkyl hydrogen to the electron donor was evidenced by distinct red shifts of the CH2 stretching modes of cyclopentadiene in the infrared spectrum. An additional ΝΗ···π interaction was evidenced by the red shift of an olefinic C−H stretching mode. Ab initio calculations yield a complex with NH3 located above the ring, oriented by both of these hydrogen-bonding interactions. The calculated interaction energy of the complex is 2.40 kcal/mol, with the energy being divided equally between these two interactions. This study represents the first example of an sp3-hybridized carbon on a hydrocarbon taking part in a C−H···N(O) hydrogen bond.

Sustainability is emerging as a prominent curricular initiative at the undergraduate level, and as a result, involving students in real-world problems in the classroom and laboratory is an important goal. The specific problem of a dwindling supply of clean and safe drinking water is also of utmost importance and relevance. This general chemistry laboratory curriculum provides first-year students with an opportunity to design and implement their own experiments that employ fruit and vegetable peels as adsorbents to remove pollutants from water. The project is nine laboratory periods long, with the first 2 weeks devoted to providing students with the necessary tools to perform original research. In the third week, students visit the Dickinson College farm and brainstorm possible hypotheses. Working in pairs, students perform original research in the fourth through sixth weeks and investigate adsorption capacity and percent removal. In the final 3 weeks, students perform calculations and engage in peer review of their posters, which are presented at an all-college public poster session. This project introduces students to UV−vis and AA spectroscopy, making standard solutions and employing Beer's Law, as well as literature searching and experiment design. If time allows, FTIR spectroscopy may be employed to examine the chemical makeup of the peels. This curriculum can be used in subsets with additional guidance in a standard two-semester introductory course sequence.

The nonscience majors course described here employs the book titled Napoleon's Buttons: How 17 Molecules Changed History as its key pedagogical tool. The book is an engaging account of 17 molecules or groups of molecules that have, like the tin buttons worn by Napoleon and his army, greatly influenced the course of history. Napoleon's Buttons frequently discusses how slight variations in the structure of a molecule can have a large impact on its properties. This theme provides the basis for both the classroom and laboratory components of the course. In addition, the major goal of the course is the compilation of our class book (modeled after Napoleon's Buttons), with each student contributing a specific molecule as a chapter. This unique approach encourages students to think in depth about how an individual molecule can shape historical events and how these events can, in turn, have an impact on the field of chemistry. Therefore the focus of this course is on the role of chemistry in history rather than on the history of chemistry. Students expressed that the project fostered camaraderie and the course helped them to become more interested in the role of chemistry in their lives.

Hydrogen bonding plays a key role in the formation of nanostructures, as it is the "glue" between layers that are built by the layer-by-layer technique. Poly(4-vinylpyridine) (PVP) is one of the most commonly used polymers in these sandwich-structured films, often in conjunction with poly(carboxylic acid)s such as poly(acrylic acid) in the PVP/PAA interpolymer complex. In addition, PVP is commonly used as a polymer matrix for embedding semiconductor nanoparticles. In this study, hydrogen-bonded complexes of water, formic acid, and pentachlorocyclopropane, with pyridine in a traditional matrix isolation experiment and PVP in a novel "polymer soft-landing" isolation experiment, have been characterized for the first time at 16 K. Changes in vibrational modes of the proton donor species and in some cases pyridine modes provided ample evidence for complex formation. In the case of water and pentachlorocyclopropane, the matrix and polymer soft-landing results were quite similar, whereas formic acid formed a significantly different complex with pyridine in the argon matrix than with the pyridine ring on the PVP polymer. This work demonstrates clearly the benefit of using both the conventional matrix isolation technique and our polymer soft-landing variation in tandem to probe the structure of these complexes and thus elucidate the nature of the C-H···N, C-H···O═C, and O-H···N linkages.