The goal of Proton NMR Basics is to bring a sense of reality to NMR spectral interpretation for the beginning organic chemistry student. Special features of the CD can help in teaching the complex subject of NMR. Students are introduced to the actual operation of the NMR spectrometer, not by simulation, but by digital video. In another segment of the program, voice-over analysis guides the student through the interpretation of several spectra. As peaks are highlighted, corresponding atoms of a three-dimensional molecular model are accented to reinforce the relationship between molecular structure and the spectrum. The importance of symmetry is emphasized by allowing the student to rotate the molecular models. The presentation can be projected for use in a classroom or it can be used by small groups or individual students. The main menu allows easy access to the four segments: Introduction, The Instrument Room, The Classroom, and The Laboratory. A HELP button is available to assist with navigation. Intermissions should be planned when using the program, for it is too extensive to assimilate all at one time. Summaries, suggested uses, and approximate lengths of time of the segments are outlined below.

The Introduction (5 minutes) acquaints the student with how proton NMR can be used to distinguish between two compounds. For most of our students, NMR will be a totally new instrument and method of analysis. This segment helps get students started. The emphasis is on looking at each spectrum as a picture, noting the general features. The Introduction also defines the terms: nuclear, magnetic, and resonance. Projection for the classroom is a good idea because of the colorful graphics, audio and video sections. The Introduction can be bypassed during future use of the CD.

Next, the student should view the segment called The Instrument Room. There are two parts to this segment: The Machine and the Theory. The Machine (10 minutes) allows the student to see and hear the instrument in use. Projection of this section for classroom use works well for it contains both audio and video. For students without access to an NMR spectrometer, seeing the instrument in action will strengthen understanding of the generation of the spectra. For students with access to an instrument, this section will set the stage for their use of the instrument.

Next is the most intense part of the program, The Theory (15 minutes). This section contains more text than any other part, along with graphics and animation. It has no audio. Individual student or small group access to The Theory section will maximize the interactivity of the program. Classroom projection can be done, with the instructor reading the text aloud. Hypertext and the Word List (Glossary) assist in understanding this section. Inspection of the Word List indicates the scope of the Theory Section. Terms included are: Aromatic, Chemical Shift, Conjugated, Coupling Constant, Delta Scale, Deshielded/Shielded, Downfield/Upfield, Electromagnetic Spectrum, Electronegative, Fourier Transform, Free Induction Decay, Integration, Radio Frequency Waves, Resonance, Ring Current, Rule for (n+1), Spin Flip, Spin Quantum Number, Splitting Pattern, Tetramethyl Silane, and Superconductivity.

The Classroom (20 minutes) carefully explains how to interpret the NMR spectra of six simple molecules: acetone, methyl acetate, benzene, ethyl acetate, 2-propanol, and methyl 2-butenoate. The molecules are presented in the order given, but can be accessed in any order. The voice-over narration imparts the feeling of a private tutor for the student. Features of the spectrum are correlated with relevant atoms of a three-dimensional molecular model. Summary text appears coincidentally with the voice-over analysis. Finally, the student is encouraged to rotate the molecular model while inspecting it for symmetry. This segment is ideal for classroom projection and equally effective when used by small groups or individual students. It is easy to repeat any part of the interpretation by clicking on the summary text. The Word List (Glossary) is always available to refresh students' memories about terms introduced in The Theory section. The natural follow-up is to have a class discussion of the interpretation of other spectra, which could be obtained from very good commercially available software, for example: SpectraDeck (1), The Schatz Index (2), and Proton Nuclear Magnetic Resonance Spectrum Simulator (3). Also students could be sent home with several spectra to interpret. Proton NMR Basics should be made available as a resource for individual student review.

The final segment, The Laboratory (5 minutes), is a look at more advanced applications of proton NMR, using as an example a classic study of an enzyme. Information about folding of the peptide chain is deduced from changes in the NMR spectrum that occur when cyclic CMP is added to the binding site of ribonuclease. Projection to a class is ideal because this segment contains graphics, voice, and video. Now students will have an idea of the real potential of the instrument. Students who are familiar with biomolecules should find this section especially interesting.

Citations

1. Schatz, P. F., SpectraDeck, Falcon Software, Inc.
2. Schatz, P. F., The Schatz Index, Falcon Software, Inc.
3. Black, K. A., Proton Nuclear Magnetic Resonance Spectrum Simulator J. Chem. Educ.: Software, 1990, Volume 2 C, (1).