A new photo-switchable "on-off" host-guest system comprising cucurbit[7]uril (CB[7]) and a photoresponsive cinnamamide derivative (trans-(3-phenyl-acryloylamino)-acetic acid, E-1) is studied. The cinnamamide derivative and CB[7] forms a stable 1 : 1 host-guest complex (CB[7]·E-1) with a high binding constant (K = 2.1 × 10(4) M(-1)). Irradiation of UV light (300 nm) to an aqueous solution of CB[7]·E-1 induces the E- to Z-conformational change of the cinnamamide derivative, which then leads to the dissociation of the complex as evidenced by UV-visible and (1)H-NMR spectroscopy. The reverse process, photo-induced host-guest complex formation between CB[7] and Z-1 is achieved by irradiation of UV light at 254 nm. The photo-switchable "on-off" host-guest system shows high reversibility and switching efficiency, which makes it potentially useful in designing photoresponsive gating systems.
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http://dx.doi.org/10.1039/c1pp05055a | DOI Listing |
Angew Chem Int Ed Engl
November 2024
Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, United Kingdom.
We report a light-responsive tetrahedral metal-organic capsule that binds a perrhenate catalyst, which is released selectively upon irradiation with 350 nm light, turning on the catalytic reduction of organic carbonyls by hydrosilanes. The catalytic activity can be switched off by heating at 75 °C for 2.5 h, which stimulates capsule reformation and catalyst re-encapsulation.
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September 2022
Chair of Inorganic Coordination Chemistry, Institute of Inorganic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
Invited for the cover of this issue are Gereon Niedner-Schatteburg, Biprajit Sarkar and co-worker at TU Kaiserslautern and the University of Stuttgart. The image depicts the selective dissociation of an axial CO from a metal complex. Read the full text of the article at 10.
View Article and Find Full Text PDFChemistry
September 2022
Chair of Inorganic Coordination Chemistry, Institute of Inorganic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
This work tackles the photochemistry of a series of mononuclear Cr , Mo and W carbonyl complexes containing a bidentate mesoionic carbene ligand of the 1,2,3-triazol-5-ylidene type. FTIR spectroscopy, combined with density functional theory calculations, revealed a clean photo-induced reaction in organic solvents (acetonitrile, pyridine, valeronitrile) to give mainly one photoproduct with monosubstitution of a carbonyl ligand for a solvent molecule. The highest photodissociation quantum yields were reached for the Cr complex under UV irradiation (266 nm).
View Article and Find Full Text PDFChem Asian J
December 2021
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Science, Zhejiang Normal University, 688 Yingbin Road, 321004, Jinhua, P. R. China.
A photo-switchable hetero-complementary quadruple H-bonding array, which consists of an azobenzene-derived ureidopyrimidinone (UPy) module (Azo-UPy) and a nonphotoactive diamidonaphthyridine (DAN) derivative (Napy-1), is constructed based on a reversible photo-locking approach. Upon UV (390 nm)/Vis (460 nm) light irradiations, photo-switchable quadruple H-bonded dimerization between Azo-UPy and Napy-1 can be achieved with exhibiting 4.8×10 -fold differences in binding strength (ON/OFF ratios).
View Article and Find Full Text PDFRSC Adv
February 2019
Key Laboratory for Organic Electronics & Information Displays, Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications 9 Wenyuan Road Nanjing 210023 China +86 25 8586 6999 +86 25 8586 6008.
A photo-switchable and high-contrast bio-imaging indicator 4,4'-(1,1')-(4,4'-(cyclopentene-1,2-diyl)bis(5-methylthiophene-4,2-diyl))bis(methan-1-yl-1-ylidene)bis(azan-1-yl-1-ylidene)bis(2-(benzo[]thiazol-2-yl)phenol) (BMBT) has been demonstrated, by integrating photochromophore with excited-state intramolecular proton transfer (ESIPT) moiety. The ability of reversible emission switching enables arbitrarily selective labeling or concealing of cells simply by controlling light irradiation. Besides, when the emission was switched on, BMBT is demonstrated to exhibit unique characteristics of aggregation induced emission (AIE), providing a high on-off ratio for favorable bio-imaging.
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