Electric Properties of Photochromic Molecules Physisorbed on Silver and Copper Nanoparticles

Abstract

This paper investigates the electric properties of the photochromic dihydroazulene/vinylheptafulvene system as it is physisorbed onto silver and copper nanoparticles. Our focus is on how the polarizability and hyperpolarizability of the dihydroazulene, s-cis-vinylheptafulvene, and s-trans-vinylheptafulvene molecules depend on molecular orientation with respect to the nanoparticles, the molecule–cluster separation, and the type of nanoparticle. The computational approach utilizes a combined quantum mechanical/molecular mechanical method in which the molecules are treated quantum mechanically while the nanoparticles are treated with a simpler classical method. The molecules are described with density functional theory. The electric properties are calculated using response theory utilizing the long-range-corrected functional CAM-B3LYP and the correlation consistent basis set aug-cc-pVDZ. The atoms of the nanoparticles are represented using atomic polarizabilities. The interactions between the nanoparticles and the molecular systems are calculated using a polarizable embedding scheme after which the molecular properties are calculated with time-dependent density functional theory. The results show that the electric properties are indeed affected by the presence of the nanoparticles. It is also clear that it is the hyperpolarizabilities that change the most while the polarizabilities are less affected. Furthermore, the influence of the nanoparticles on the molecules depends heavily on the relative molecular orientation with respect to the nanoparticles and molecular conformation. Finally, it is observed that a copper nanoparticle has a larger influence on the molecular systems than a silver nanoparticle.

Aza-bicyclooctadiene/tetracyclooctane couples as promising photoswitches for molecular solar thermal energy storage applications

“…1,7,12,15,27,35,40,44,[47][48][49] Numerous attempts have also been made by Mikkelsen and co-workers to tune the properties of different molecular photoswitches in the theoretical studies. [13][14][15][31][32][33][34]43,45,48,[50][51][52][53][54] Bicyclooctadiene (BOD) is a bicyclic organic molecule that shows structural similarity with norbornadiene (NBD) and it is recently reported to exhibit enhanced thermochemical properties for MOST application. 14,15 Any structural modification in the BOD with an objective to improve the photophysical and thermochemical properties is of enduring interest.…”

“…1,7,12,15,27,35,40,44,47–49 Numerous attempts have also been made by Mikkelsen and co-workers to tune the properties of different molecular photoswitches in the theoretical studies. 13–15,31–34,43,45,48,50–54…”