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- ItemPhotoswitching of DNA Hybridization Using a Molecular Motor(Washington, DC : ACS Publications, 2018) Lubbe, Anouk S.; Liu, Qing; Smith, Sanne J.; de Vries, Jan Willem; Kistemaker, Jos C. M.; de Vries, Alex H.; Faustino, Ignacio; Meng, Zhuojun; Szymanski, Wiktor; Herrmann, Andreas; Feringa, Ben L.Reversible control over the functionality of biological systems via external triggers may be used in future medicine to reduce the need for invasive procedures. Additionally, externally regulated biomacromolecules are now considered as particularly attractive tools in nanoscience and the design of smart materials, due to their highly programmable nature and complex functionality. Incorporation of photoswitches into biomolecules, such as peptides, antibiotics, and nucleic acids, has generated exciting results in the past few years. Molecular motors offer the potential for new and more precise methods of photoregulation, due to their multistate switching cycle, unidirectionality of rotation, and helicity inversion during the rotational steps. Aided by computational studies, we designed and synthesized a photoswitchable DNA hairpin, in which a molecular motor serves as the bridgehead unit. After it was determined that motor function was not affected by the rigid arms of the linker, solid-phase synthesis was employed to incorporate the motor into an 8-base-pair self-complementary DNA strand. With the photoswitchable bridgehead in place, hairpin formation was unimpaired, while the motor part of this advanced biohybrid system retains excellent photochemical properties. Rotation of the motor generates large changes in structure, and as a consequence the duplex stability of the oligonucleotide could be regulated by UV light irradiation. Additionally, Molecular Dynamics computations were employed to rationalize the observed behavior of the motor–DNA hybrid. The results presented herein establish molecular motors as powerful multistate switches for application in biological environments.
- ItemModulating the luminance of organic light-emitting diodes: Via optical stimulation of a photochromic molecular monolayer at transparent oxide electrode(Cambridge : RSC Publ., 2020) Ligorio, Giovanni; Cotella, Giovanni F.; Bonasera, Aurelio; Zorn Morales, Nicolas; Carnicella, Giuseppe; Kobin, Björn; Wang, Qiankun; Koch, Norbert; Hecht, Stefan; List-Kratochvil, Emil J.W.; Cacialli, FrancoSelf-assembled monolayers (SAMs) deposited on bottom electrodes are commonly used to tune charge carrier injection or blocking in optoelectronic devices. Beside the enhancement of device performance, the fabrication of multifunctional devices in which the output can be modulated by multiple external stimuli remains a challenging target. In this work, we report the functionalization of an indium tin oxide (ITO) electrode with a SAM of a diarylethene derivative designed for optically control the electronic properties. Following the demonstration of dense SAM formation and its photochromic activity, as a proof-of-principle, an organic light-emitting diode (OLED) embedding the light-responsive SAM-covered electrode was fabricated and characterized. Optically addressing the two-terminal device by irradiation with ultraviolet light doubles the electroluminescence. The original value can be restored reversibly by irradiation with visible light. This expanded functionality is based on the photoinduced modulation of the electronic structure of the diarylethene isomers, which impact the charge carriers' confinement within the emissive layer. This approach could be successfully exploited in the field of opto-communication technology, for example to fabricate opto-electronic logic circuits. © 2020 The Royal Society of Chemistry.