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Charge Transport through Self‐Assembled Monolayers of Monoterpenoids
Author(s) -
Cafferty Brian J.,
Yuan Li,
Baghbanzadeh Mostafa,
Rappoport Dmitrij,
Beyzavi M. Hassan,
Whitesides George M.
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201902997
Subject(s) - degree of unsaturation , monolayer , chemistry , molecule , self assembled monolayer , charge (physics) , chemical physics , conductivity , self assembly , electrode , carbon fibers , quantum tunnelling , stereochemistry , organic chemistry , materials science , optoelectronics , physics , quantum mechanics , composite number , composite material , biochemistry
The nature of the processes at the origin of life that selected specific classes of molecules for broad incorporation into cells is controversial. Among those classes selected were polyisoprenoids and their derivatives. This paper tests the hypothesis that polyisoprenoids were early contributors to membranes in part because they (or their derivatives) could facilitate charge transport by quantum tunneling. It measures charge transport across self‐assembled monolayers (SAMs) of carboxyl‐terminated monoterpenoids (O 2 C(C 9 HX)) and alkanoates (O 2 C(C 7 HX)) with different degrees of unsaturation, supported on silver (Ag TS ) bottom electrodes, with Ga 2 O 3 /EGaIn top electrodes. Measurements of current density of SAMs of linear length‐matched hydrocarbons—both saturated and unsaturated—show that completely unsaturated molecules transport charge faster than those that are completely saturated by approximately a factor of ten. This increase in relative rates of charge transport correlates with the number of carbon–carbon double bonds, but not with the extent of conjugation. These results suggest that polyisoprenoids—even fully unsaturated—are not sufficiently good tunneling conductors for their conductivity to have favored them as building blocks in the prebiotic world.