METHODS FOR THE STUDY OF MOLECULAR RECOGNITION PROCESSES

The course aims to provide students with fundamental concepts and tools for the study of chemical equilibria and the determination of complex species, stability constants and driving forces of molecular recognition processes in solution by using common analytical techniques as well as methods and software for data analysis.

Knowledge and understanding:

Knowledge of the essential concepts for the study of molecular recognition and host-guest equilibria as well as for the determination of the main binding parameters.

Applying knowledge and understanding:

Development of tools for understanding and applying the most common analytical techniques, the optimization of the experimental conditions, the determination and quantification of the species and the driving forces of molecular recognition events. Development of a critical way of thinking for the presentation of the analytical data obtained.

Making judgements:

Capability to solve problems on solution equilibria involving ionic and/or molecular species as well as to collect, analyze and critically interpret experimental data basing on the acquired knowledge.

Communication skills:

Acquiring proper language skills and ability to rigorously expose the topics covered in the course.

Learning skills:

Capability to develop tools and skills to successfully undertake further study paths with a high level of autonomy.

Class lectures

Should teaching be carried out in mixed mode or remotely, it may be necessary to introduce changes with respect to previous statements, in line with the programme planned and outlined in the syllabus

Key concepts of General and Inorganic, Analytical (mostly, solution equilibria and instrumental analysis) and Organic Chemistry

Attending all the class lectures is mandatory

Molecular recognition: basic principles. Weak, non-covalent interactions. Hydrophobic effect. Complexation of charged and/or neutral species in solution. Receptors and supramolecular capsules for the recognition of cationic, anionic and neutral guests.

Host-guest complex equilibria. Multiple equilibria. Ligand competition. Role of ionic strength, solvent and pH on molecular recognition equilibria. Acid-base equilibria and species distribution. Conditional stability constant. pH control: choice of the most efficient buffering agents.

Determination of complex species and stability constants through analytical techniques (UV-vis, NMR, ITC). Optimization of the experimental conditions for a host-guest titration. Selection of the proper technique and concentration range. Complexation ratio and probability of binding. Relationship between the observable and the species concentration. Binding isotherm. Graphical methods for the determination of both stoichiometry and binding constant, main issues.

Data treatment. Non-linear least-squares analysis. Major software. Simulation of a UV-vis titration and data analysis.

Determination of the driving forces of molecular recognition processes in solution. Determination of ΔH for a reaction: direct measurement of the heat vs. van’t Hoff method. Isothermal titration calorimetry (ITC). Instrument calibration. Determination of K and ΔH of a reaction through ITC titrations. Calorimetric data analysis, main models and software. Simultaneous analysis of different observables for the study of multiple equilibria in complex host-guest systems.

Basic concepts on molecular recognition at the solid-liquid interface. SPR and QCM-D techniques. Real-time monitoring of molecular interactions at the interface.

Selected chapters from the following textbooks:

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

2. J. W. Steed, D. R. Turner, K. Wallace, Core Concepts in Supramolecular Chemistry and Nanochemistry, John Wiley & Sons, 2007

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

4. 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

5. J. W Steed, P. A. Gale editors, Supramolecular Chemistry: From Molecules to Nanomaterials, Vol. 1-3, John Wiley & Sons, 2012

6. D. C. Harris, Chimica Analitica Quantitativa, terza ed., Zanichelli, Bologna, 2017

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

The oral exam is intended to ascertain the knowledge of the student upon the topics presented and discussed during the class lectures. The use of a proper scientific language as well as of a critical approach to solve issues related to analytical chemistry and its applications will be also evaluated.

The tests might be carried out also remotely/on-line if required by special conditions/events.

Hosts for the recognition of cationic guests. Hydrophobic effect. Role of pH on the host-guest complex formation. Choice of the buffering agents. Experimental conditions for a host-guest titration. Graphical methods for data treatment. Least-squares analysis. Principles of the ITC technique. Analysis of calorimetric data.