PHYSICAL METHODS IN ORGANIC CHEMISTRY AND LABORATORY
Learning outcomes of the course unit
Knowledge and understanding
The aim of the course is to provide students with a thorough knowledge of the most common advanced 1D and 2D NMR techniques for structural analysis or organic compounds. In particular, at the end of the course the student will be able to:
• autonomously identifying the structure of organic compounds by interpreting a series of 1D and 2D NMR spectra;
• use scientific instruments to elaborate experimental data, to execute the analysis and the characterization of real samples;
• use computational methods for data processing.
• plan and complete an experiment through individual and /or group activities.
• autonomously collect experimental data and design the experimental activities;
• critically evaluate the experimental results;
• evaluate the quality parameters of alternative analytical techniques according to the nature of the experimental problem, as well as the possibilities and limits of more advanced analytical and characterization techniques by tackling and solving complex problems related to them.
• sustain a contradictory on the basis of opinions developed independently on issues related to their studies and make team-working in multidisciplinary projects.
• autonomously learn new scientific topics.
• autonomously tackle on new professional problems;
• autonomously study new solutions to complex problems, including interdisciplinary ones.
Course contents summary
Magnetic properties of nuclei: angular momentum and spin angular momentum.
The Vector model.
Fundamental concepts of 2D NMR spectroscopy.
The Chemical exchange.
The modern NMR spectrometer.
Interpretation of 1D e 2D NMR spectra and determination of the structure of an organic compound.
Laboratory part: use of the NMR spectrometer and recording of several 1D (1H and 13C) and 2D (COSY and HSCQ) NMR spectra of organic compounds.
• NMR Frequencies and Chemical shift. Linewidth and lineshape. Scalar coupling. The basic NMR experiment.
• Energy levels and NMR spectra. The spectrum for one spin. The energy levels for two coupled spins.
• The Vector model. The bulk magnetization. Larmor precession. Detection. Pulses. "On resonance" pulses. The rotating frame. The basic impulse-acquisition sequence. Calibration of pulses. The Spin-Echo experiment. Pulses of various phase. "Off-resonance" effetcs and "soft" pulses. Fourier Transformation and data processing. FID representation. Peaks linewidth and lineshape. FID manipulation. Zero filling.
• The modern NMR spectrometer. Magnet and Probe, Lock Channel, Shim and homogeneity of the magnetic field. RF synthesizer, amplifier and duplexer. Receiver and Quadrature detection. Analogue to digital convertor (ADC). Limits of digitization.
• The "Product Operators" formalism. Product operators for one spin. Hamiltonians for spins and delays. Equation of motion. The spin-echo experiments with the product operators formalism. Product operators for two weakly coupled spins.
• Fundamental concepts of 2D NMR spectroscopy. 2D NMR experiments with coherence transfer mediated by J-coupling. COSY and DQF-COSY: pulses sequence and spectra interpretation. Double Quantum NMR Spectroscopy. Heterocorrelated 2D NMR spectroscopy. HMQC, HSQC and HMBC experiments: pulses sequence and spectra interpretation. 2D TOCSY NMR experiment: pulses sequence and spectra interpretation.
• Relaxation and Nuclear Overhauser Effect (NOE). The origin of the nuclear relaxation phenomenon. Mechanisms of relaxation. Correlation time. Population of the states. Longitudinal relaxation of isolated spins. Dipolar longitudinal relaxation of two spins. Cross-relaxation. Relaxation due to chemical shift anisotropy.
• NOEDif, NOESY and ROESY experiments: pulses sequence and spectra interpretation
• Coherence selection: phase cycling cycle and field gradient pulses. Order of coherence. Coherence transfer pathways. Frequency discrimination and peak shape.
• 1D and 2D NMR spectra acquisition and processing (1H and 13C).
Lecture notes by the Professor, examples of exercises and cases of study proposed during the examination. All this material is available at the website on Elly platform from the beginning of the course. It constitutes the main support for the preparation of the exam.
• Harald Gunther - NMR Spectroscopy, Basic Principles, Concepts, and Apllication in Chemistry, 3rd edition, Wiley - VCH, 2013.
• Oliver Zerbe & Simon Jurt - Applied NMR Spectroscopy for Chemists and Life Scientists, Wiley-VCH, 2014.
Suggested Readings (Theory):
• James Keller "Understanding NMR Spectroscopy", 2nd Edition, Wiley, 2010.
• Neil E. Jacobsen - NMR Data Interpretation explained, Wiley, 2016
• Antonio Randazzo - Guida pratica alla interpretazione di spettri NMR, Loghia, 2017.
Suggested Readings (Lab.):
• John S. Harwood & Huaping Mo - Practical NMR Spectroscopy Laboratory Guide: Using Bruker Spectrometers, Academic Press, 2015
• Matthias Findeisen & Stefan Berger - 50 and More Essential NMR Experiments: A Detailed Guide, Wiley-VCH, 2013
The format of the class will be lectures of one or two hours each spread over three days per week. The lab training will be articulated in four experiments of two hours each.
Assessment methods and criteria
The final examination will include a written part in which the candidates have to assign the structure of a known organic compounds to the resonances of several 1D and 2D NMR spectra (MAX. 21/30). In the following oral part, the candidates will be enquired on the theoretical topics discussed during the first part of the course (MAX. 9/30).
The demonstration of a basic knowledge of the contents of the course, which includes the ability to assign the resonances of 1D and 2D NMR spectra to the structure of an organic compound, determines a score of 18-21/30. A precise description of the instrumental and experimental aspects of the NMR technique determines a score of 21-24/30. A comprehensive and in-depth discussion of the theoretical aspects of the NMR spectroscopy with answers given using an appropriate language will be awarded with a score of 27-30/30. The ability of the candidate to face new problems together with the identification of possible problems and applications determines the assignment of an evaluation with honors.