Chemistry

Chemical ecology is the study of how chemicals, called semiochemicals, mediate interactions within and between species. Such interactions are very diverse, including, within species, mating, intraspecific competition, social status and foraging and, between species, predation and parasitism, defense and mutualisms such as pollination. This course examines how the different semiochemicals originate and how they are used and detected by organisms. Examine how chemists and biologists study these interactions and how some of these interactions can be used to assist humans, by manipulating organisms in the nature. Students are encouraged to develop their own interests, and the course is not limited to one particular organismic group. Both biologists and chemists are encouraged to join the course. Pre-requisites include BIO2001 Cell Biology and CHE2001 Organic Chemistry.

This course is part of the Laurea Magistrale degree program and is intended for advanced level students. Enrollment is by permission of the instructor. Students acquire knowledge of Coordination Chemistry and are familiar with common theories concerning metal ligand bond, the synthesis and properties of coordination compounds, including most simple organometallic compounds. At the end of the course, students are able to relate the nature of the different metal-ligand combinations with the properties of the complexes and their possible use in different application fields including: catalysis, functional materials, bioinorganic and supramolecular chemistry.

Course contents: 

I. The inorganic elements in the periodic table (6 hours)

Non-metals, metalloids and metals in the periodic table: electron configuration, characteristics, bonding, reactivity.

II. Coordination complexes and the metal-ligand bonding (8 hours)

a) General aspects. Metal ions: electron configuration, the d sub-shell in transition metals, the f sub-shell in lanthanides. Ligands: definition, the Lewis acid/base model. Multidentate ligands and chelates. Geometry. Nomenclature.

b) The metal-ligand bonding. The molecular orbital model: octahedral and tetrahedral complexes. Sigma/pi-donor, pi-acceptor ligands. Link with the crystal field theory: high spin/low spin complexes.

III. Spectroscopic investigation of transition metal complexes (12 hours)

a) UV-visible spectroscopy: spectral terms, Orgel diagrams, Tanabe-Sugano diagrams, intervalence charge transfer.

b) Mid-infrared and near infrared spectroscopies: application to carbonyl and cyano complexes, and to organic ligands.

c) Emission spectroscopy: basics, the Jablonski diagram, definition of quantum yield and emission lifetime. Luminescence from organic compounds and heavy-metal complexes and lanthanides.

IV. Reactivity of metal complexes: (18 hours)

a) Contributions to the stabilization energy of complexes: electrostatic interaction, crystal field stabilization energy, the HSAB model. Influence of the size and charge of the metal ion. S-p metals vs. transition metals : comparison.

b) Ligands substitution: inert/labile complexes, link with the crystal field theory, the trans effect.

c) Reactivity in organometallic chemistry: the 18-electron rule, oxidative addition, reductive elimination. Application to homogeneous catalysis

d) Excited states as new chemical species: different energy, lifetime, geometry, dipole moment. The case of [Ru(bpy)3]2+.Application to artificial photosynthesis and solar light harvesting

e).Luminescent metal complexes and lanthanide-based compounds: fundamentals and application to materials (light emitting devices) and life science (bioimaging and biosensing).

f) Photocatalytic processes mediated by transition metal complexes.