METODI PER LO STUDIO DI PROCESSI DI RICONOSCIMENTO MOLECOLARE

The course aims to provide students with fundamental concepts and tools for the study of solution equilibria and for the determination of complex species, stability constants and driving forces of molecular recognition processes in solution through the most common analytical techniques as well as methods and software for data analysis. Basic concepts on real-time monitoring of recognition/binding events occurring at the solid-liquid interface will be also presented.

Class lectures

Weak, non-covalent interactions: general concepts. Complexation of charged and/or neutral molecules in solution. Natural and synthetic receptors for molecules.

Host-guest complex equilibria. Multiple equilibria. Ligands competition. Role of pH, ionic strength and solvent on molecular recognition equilibria. Use of buffering agents. Conditional stability constant.

Determination of complex species and stability constants through the most common analytical techniques: absorption, fluorescence and NMR spectroscopy, electrochemistry. Titration design. Errors in data collection. Graphical methods for the determination of both stoichiometry and binding constants of host-guest complexes: main advantages and issues.

Data treatment. Non-linear least-square analysis. Major software. Analysis of titration data through spreadsheets. Case study: determination of the binding constant of a host-guest complex through non-linear least-square analysis of spectroscopic or calorimetric data.

Determination of the energetics of reaction and the driving forces of molecular recognition processes in solution. Attractive interactions, role of the solvent and of the guest. Hydrophobic effect. Isothermal titration calorimetry (ITC). Direct measurement of the heat of a reaction vs. van’t Hoff method. Determination of K e ΔH of a reaction through ITC titrations. Calorimetric data analysis. Models for the study of multiple equilibria.

Molecular recognition at the solid-liquid interface. Surface plasmon resonance (SPR) and quartz crystal microbalance with dissipation monitoring (QCM-D): general principles and applications. Real-time monitoring of recognition events occurring in (bio)molecular systems. Determination of affinity constants and reaction kinetics.

1. J. W Steed, J. L. Atwood, Supramolecular Chemistry, 2° ed., John Wiley & Sons, 2009

2. J. L. Atwood, G. W. Gokel, L. Barbour editors, Comprehensive Supramolecular Chemistry II, 2 ed., Vol. 2: Experimental and computational methods in supramolecular chemistry, Elsevier, 2017

3. E. V. Anslyn, D. A. Dougherty, Modern Physical Organic Chemistry, University Science Books, 2005

4. D. A. Skoog, D. M. West, F. J. Holler, S. R. Crouch, Fondamenti di Chimica Analitica, 3° ed., Edises, 2015

5. E. J. Billo, Excel for Chemists: A Comprehensive Guide, 2nd ed.; Wiley-VCH: New York, 2001