A synthetic five-part molecular device has been prepared that uses a multistep electron transfer strategy similar to that of photosynthetic organisms to capture light energy and convert it to chemical potential in the form of long-lived charge separation. It consists of two covalently linked porphyrin moieties, one containing a zinc ion (P(Zn)) and the other present as the free base (P). The metailated porphyrin bears a carotenoid polyene (C) and the other a diquinone species (Q(A)-Q(B)). Excitation of the free-base porphyrin in a chloroform solution of the pentad yields an initial charge-separated state, C-P(Zn)-P(.+).-Q(A)(-)-Q(B), with a quantum yield of 0.85. Subsequent electron transfer steps lead to a final charge-separated state, C(.+)-P(Zn)-P-Q(A)-Q(B)(.-), which is formed with an overall quantum yield of 0.83 and has a lifetime of 55 microseconds. Irradiation of the free-base form of the pentad, C-P-P-Q(A)-Q(B), gives a similar charge-separated state with a lower quantum yield (0.15 in dichloromethane), although the lifetime is increased to approximately 340 microseconds. The artificial photosynthetic system preserves a significant fraction ( approximately 1.0 electron volt) of the initial excitation energy (1.9 electron volts) in the long-lived, charge-separated state.
While cheminformatics skills necessary
for dealing with an ever-increasing
amount of chemical information are considered important for students
pursuing STEM careers in the age of big data, many schools do not
offer a cheminformatics course or alternative training opportunities.
This paper presents the Cheminformatics Online Chemistry Course (OLCC),
which is organized and run by the Committee on Computers in Chemical
Education (CCCE) of the American Chemical Society (ACS)’s Division
of Chemical Education (CHED). The Cheminformatics OLCC is a highly
collaborative teaching project involving instructors at multiple schools
who teamed up with external chemical information experts recruited
across sectors, including government and industry. From 2015 to 2019,
three Cheminformatics OLCCs were offered. In each program, the instructors at participating schools would
meet face-to-face with the students of a class, while external content
experts engaged through online discussions across campuses with both
the instructors and students. All the material created in the course
has been made available at the open education repositories of LibreTexts
and CCCE Web sites for other institutions to adapt to their future
needs.
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