Giacomo Ciamician

Giacomo Ciamician (1857-1922) studied in Vienna and after teaching in Rome was awarded a prize by the Accademia dei Lincei for his work on pyrrol chemistry. He was appointed to a Chair first in Padua, then in Bologna. His contribution to the science of chemistry was outstanding: from physical and theoretical chemistry, to the chemistry of natural substances (essences of plants such as aniseed, saxifrage, parsley and celery) and organic photochemistry, of which he is recognised to be the founder. While studying spectroscopy in Vienna, Ciamician made an important discovery, that was later to lead to the concept of energy levels of atoms: elements in the same family of the periodic table have remarkably similar emission spectra. Since quantum theory had not yet been developed, the young scientist formulated a theory that attributed spectral similarities to the fact that elements in the same group share certain components. From the study of pyrrols, Ciamician's research focused on the structure and chemistry of substances of vegetable origin, and from this to the chemical effects of light. These studies, the results of which were reported in 85 papers published in German in the series Chemische Lichtwirkungen, led to the discovery of many new reactions, including the photoreduction of aldehydes, kenones, quinones and nitro compounds, the photodimerisation and the photochemical cycloaddition of olefins, the photohydrolytic fragmentation of ketones, and the intramolecular photochemical disproportioning of ortho-nitrobenzaldehyde. This research opened up a new branch of chemistry, and placed Ciamician among the leading scientists of his time, thus bringing world renown to Italian chemical research.

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