Promoting Z‑to‑E Thermal Isomerization of Azobenzene Derivatives by Noncovalent Interaction with Phosphorene: Theoretical Prediction and Experimental Study

• Published in: Journal of physical chemistry. C Vol. 124; no. 29; pp. 15961 - 15968
• Main Authors: Zheng, Dong, Ding, Mengning, Hu, Yi, Zhao, Jun, Liu, Chunyan, Li, Xiang, Liu, Pingying, Jin, Zhong, Ma, Jing
• Format: Journal Article
• Language: English
• Published: American Chemical Society 23.07.2020
• Subjects: C: Surfaces, Interfaces, Porous Materials, and Catalysis
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.0c03837

The ability to modulate the rate of Z/E isomerization of azobenzene (AB) derivatives is crucial to the practical applications of biological and photofunctional systems. Four kinds of AB–OC4H8–R derivatives (AB-1, R = NMe3 +I–; AB-2, R = NH2; AB-3, R = C6H13; AB-4, R = SH) were incorporated into liquid-exfoliated black phosphorus (BP) nanosheets through noncovalent functionalization. Experiments indicated that the switching process between the two states, trans (E) and cis (Z), especially the Z-to-E thermal conversion of AB derivatives, was accelerated 2–23 times by the presence of phosphorene at temperatures of 293–313 K. The acceleration phenomenon was rationalized by density functional theory (DFT) calculations, which reveals that the interaction between phosphorene and AB derivatives stabilized the Z isomer and transition state of azobenzene in a less degree than the E isomer, hence lowering the activation energy (E a) of the Z-to-E isomerization. A close correlation is shown between the extent of charge transfer, the binding energy, and the Z-to-E thermal activation energy. The reactive molecular dynamics simulations also demonstrated a threefold faster isomerization process for AB@BP hybrids to accomplish the thermal relaxation relative to the free-standing AB. The predicted energy difference between E and Z isomers of AB@BP hybrids are enhanced 2–3 times upon deposition on the BP substrate. The photoresponsive AB@BP system suggests a new platform for energy conversion and potential applications in the biological field.