Overcrowded alkene based molecular motors and switches constitute a unique class of photo-responsive systems due to their intrinsic chirality near the core C[double bond, length as m-dash]C bond, making them highly suitable candidates for the construction of light-switchable dynamic systems, , for controlling molecular motion, modulation of material chiroptical properties and supramolecular assembly. However, the lack of general design principles, along with the challenging synthesis of these molecules, precludes full exploitation of their dynamic structures. Therefore, systematic investigations of the key parameters are crucial for the further development of these systems. Here we provide a facile alternative synthetic route, elucidate the influence of substituents on the photochemistry of overcrowded alkene-derived bistable chiroptical photoswitches, and show nearly quantitative bidirectional photoswitching. The established structure-property relationship constitutes a practical guideline for the design of these photochromes tailored to a specific application.
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http://dx.doi.org/10.1039/d2sc05903g | DOI Listing |
Molecules
October 2024
School of Physics, Shandong University, Jinan 250100, China.
The reversible photo-induced conformation transition of a single molecule with a [5]helicene backbone has garnered considerable interest in recent studies. Based on such a switching process, one can build molecular photo-driven switches for potential applications of nanoelectronics. But the achievement of high-performance reversible single-molecule photoswitches is still rare.
View Article and Find Full Text PDFJ Phys Chem B
September 2024
Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, Siena 53100, Italy.
Despite the numerous investigations of photoisomerization reactions from both the computational and experimental points of view, even in complex environments, to date there is no direct demonstration of the direction of rotation of the retinal chromophore, initiating the vision process in several organisms, occurring upon light irradiation. In the literature, many proposals have been formulated to shed light on the details of this process, most of which are extracted from semiclassical simulations. Although high hopes are held in the development of time-resolved X-ray spectroscopy, I argue in this work that simpler but less known techniques can be used to unravel the details of this fascinating photochemical process.
View Article and Find Full Text PDFChem Rev
May 2024
Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Since the last century, we have witnessed the development of molecular magnetism which deals with magnetic materials based on molecular species, i.e., organic radicals and metal complexes.
View Article and Find Full Text PDFJ Mater Chem B
April 2024
Departament of Organic Chemistry, Universidad Autónoma de Madrid, Campus de Cantoblanco, Madrid 28049, Spain.
The control of supramolecular DNA assembly through external stimuli such as light represents a promising approach to control bioreactions, and modulate hybridization or delivery processes. Here, we report on the design of nucleobase-containing arylazopyrazole photoswitches that undergo chiral organization upon self-assembly along short DNA templates. Chiroptical spectroscopy shows that the specific nucleobases allow selectivity in the resulting supramolecular DNA complexes, and UV light irradiation triggers partial desorption of the arylazopyrazole photoswitches.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2023
Key Laboratory of Medicinal Molecule Science and Pharmaceutics Engineering, Ministry of Industry and Information Technology, Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, China.
The phosphate-coordination triple helicates A L (A=anion) with azobenzene-spaced bis-bis(urea) ligands (L) have proven to undergo a rare in situ photoisomerization (without disassembly of the structure) rather than the typically known, stepwise "disassembly-isomerization-reassembly" process. This is enabled by the structural self-adaptability of the "aniono" assembly arising from multiple relatively weak and flexible hydrogen bonds between the phosphate anion and bis(urea) units. Notably, the Z→E thermal relaxation rate of the isomerized azobenzene unit is significantly decreased (up to 20-fold) for the triple helicates compared to the free ligands.
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