Carbazole structures are of high interest in photopolymerization due to their enhanced light absorption properties in the near-UV or even visible ranges. Therefore, type I photoinitiators combining the carbazole chromophore to the well-established phosphine-oxides were proposed and studied in this article. The aim of this article was to propose type I photoinitiators that can be more reactive than benchmark phosphine oxides, which are among the more reactive type I photoinitiators for a UV or near-UV light emitting diodes (LED) irradiation. Two molecules were synthesized and their UV-visible light absorption properties as well as the quantum yields of photolysis and photopolymerization performances were measured. Remarkably, the associated absorption was enhanced in the 350-410 nm range compared to benchmark phosphine oxides, and one compound was found to be more reactive in photopolymerization than the commercial photoinitiator TPO-L for an irradiation at 395 nm.
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http://dx.doi.org/10.3390/molecules25071671 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Humboldt-Universität zu Berlin, Department of Chemistry, Laboratory of Organic Chemistry and Functional Materials, Brook-Taylor-Str. 2, 12489, Berlin, GERMANY.
Here we disclose that spiropyrans are able to undergo dynamic covalent exchange via their corresponding merocyanine isomers. In the latter, the indolinium moieties can be exchanged by a Michael-type addition-elimination sequence, in which a methylene indoline attacks a merocyanine and subsequently the initial indoline fragment is cleaved. The rate and position of the exchange equilibrium strongly depend on the reaction conditions as well as the substitution pattern on the methylene indoline fragments.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
Faculty of Chemical Technology and Engineering, Bydgoszcz University of Science and Technology, 85-326 Bydgoszcz, Poland.
Billions of patients struggle with dental diseases every year. These mainly comprise caries and related diseases. This results in an extremely high demand for innovative, polymer composite filling materials that meet a number of dental requirements.
View Article and Find Full Text PDFLymphatics
September 2024
Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA.
Despite chronic fibrosis occurring in many pathological conditions, few in vitro studies examine how fibrosis impacts lymphatic endothelial cell (LEC) behavior. This study examined stiffening profiles of PhotoCol-commercially available methacrylated type I collagen-photo-crosslinked with the photoinitiators: Lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), Irgacure 2959 (IRG), and Ruthenium/Sodium Persulfate (Ru/SPS) prior to evaluating PhotoCol permeability and LEC response to PhotoCol at stiffnesses representing normal and fibrotic tissues. Ru/SPS produced the highest stiffness (~6 kilopascal (kPa)) for photo-crosslinked PhotoCol, but stiffness did not change with burst light exposures (30 and 90 s).
View Article and Find Full Text PDFOrg Lett
December 2024
Department of Chemistry, College of Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China.
A series of 3-phosphonyl polysubstituted pyridine were first synthesized by photocatalysis, combining a phosphonyl radical cascade reaction, Boc deprotection, and aromatization. This strategy can avoid the difficulties of activating the C3-H bond on pyridine to synthesize 3-phosphonylpyridine under mild conditions. Furthermore, by constructing different enynes, we can achieve the metal-free modular synthesis of 3-phosphonyl polysubstituted pyridine, which will be transferred into a new type of phosphine ligand.
View Article and Find Full Text PDFAdv Mater
November 2024
Friedrich-Alexander-Universität Erlangen-Nürnberg, Department of Chemistry and Pharmacy, Nikolaus-Fiebiger-Str. 10, 91058, Erlangen, Germany.
Molecular photoswitches produce light-controlled changes at the nanometer scale and can therefore be used to alter the states and behavior of materials in a truly bottom-up fashion. Here an escalating photonic complexity of material property control with light is shown using a recently developed aza-diarylethene in combination with hemiindigo (HI) photoswitches. First, aza-diarylethene can be used as a photoswitch in polystyrene (PS) to reversibly inscribe relief-type 3D structures into PS.
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