Dissertation

|1.6 Photocatalyzed Reactions|
an average power of approximately 100 terawatts of sunlight, natural photosynthesis directly and
indirectly provides the basis for nearly all life on earth. G. Ciamician, an important pioneer
of photochemistry research, realized the relevance of that fact (see figure 11). Although his
understanding was certainly basic, he found out that the use of solar energy would help to:
[21, 22]
(1) carry out reactions under mild conditions,
(2) look for activation conditions that allow for more direct reactions and thus improve
atom economy,
(3) increase the use of renewable materials or reagents (using directly light rather than
fossil solar energy) and
(4) minimize the use of energy.
Figure 11: Photochemistry pioneer GIACOMO CIAMICIAN, as he watches his reactions, driven by solar
irradiation in flasks on the balcony on top of his laboratory at the University of Bologna, Italy, circa
1910. [4]
Today, these statements are incorporated into the "12 principles" of green chemistry as formulated
by Anastas and Warner. [23]
According to Turro, today it is known that photochemical reactions differ from thermal reactions
in three important respects: [24] |14|