The cycloadducts of tethered naphthalene and anthracene derivatives undergo photochemical ring opening to an electronically excited product with adiabatic yields up to 90%.
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http://dx.doi.org/10.1039/c0pp00096e | DOI Listing |
J Am Chem Soc
January 2025
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Graft-through ring-opening metathesis polymerization (ROMP) of norbornene-terminated macromonomers (MMs) prepared using various polymerization methods has been extensively used for the synthesis of bottlebrush (co)polymers, yet the potential of ROMP for the synthesis of MMs that can subsequently be polymerized by graft-through ROMP to produce new bottlebrush compositions remains untapped. Here, we report an efficient "ROMP-of-ROMP" method that involves the synthesis of norbornene-terminated poly(norbornene imide) (PNI)-based MMs that, following ROMP, provide new families of bottlebrush (co)polymers and "brush-on-brush" hierarchical architectures. In the bulk state, the organization of the PNI pendants drives bottlebrush backbone extension to enable rapid assembly of asymmetric lamellar morphologies with large asymmetry factors.
View Article and Find Full Text PDFChembiochem
January 2025
Renmin University of China, Chemistry, No.59 Zhongguangcun Street, Haidian District, 100872, Beijing, CHINA.
BTG13, a non-heme iron-dependent enzyme with a distinctive coordination environment of four histidines and a carboxylated lysine, has been found to catalyze the cleavage of the C4a-C10 bond in anthraquinone. Contrary to typical dioxygenase mechanisms, our quantum mechanical/molecular mechanical (QM/MM) calculations reveal that BTG13 functions more like a monooxygenase. It selectively inserts an oxygen atom into the C10-C4a bond, creating a lactone species that subsequently hydrolyzes, leading to the formation of a ring-opened product.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Brown University, Department of Chemistry, UNITED STATES OF AMERICA.
Despite major progress in the investigation of boron cluster anions, direct experimental study of neutral boron clusters remains a significant challenge because of the difficulty in size selection. Here we report a size-specific study of the neutral B9 cluster using threshold photoionization with a tunable vacuum ultraviolet free electron laser. The ionization potential of B9 is measured to be 8.
View Article and Find Full Text PDFMacromol Rapid Commun
January 2025
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Street 5625, Changchun, 130022, China.
The demand for insulating materials with superior dielectric properties has increased. Among these materials, polymers containing cyclic structure including cyclic olefin copolymer (COC) and cyclic olefin polymer (COP) stand out because of their excellent dielectric properties originating from the pure hydrocarbon structure. Introducing fluorine into polymers is one efficient strategy for optimizing the dielectric and the related important properties.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
School of Environment and Safety Engineering, North University of China, Taiyuan, Shanxi 030051, China.
DNP (3,4-dinitropyrazole) has attracted much interest due to its promising melting characteristics and high detonation performances, such as low melting point, high density, high detonation velocity, and low sensitivity. In this work, first-principles molecular dynamics (MD) simulations were performed to investigate the anisotropic shock response of DNP in conjunction with the multiscale shock technique (MSST). The initial decomposition mechanism was revealed through the evolution of the chemical reaction and product analysis.
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