Effect of a Structure of Polymethine Dyes on the Methyl Methacrylate Free Radical Polymerization in a Solution

Near-infrared squarate and croconate dianions derived from tetranitrofluorene

“…[Extremely low solubility of the compound hampered its further NMR investigation, specifically 13 ,59.41;H,6.43;N,11.18;found: C,59.27;H,6.20;N,11.29. Triethylammonium 2,4,5,4,5,7-tetranitro-9H-fluoren-9-ylidene)cyclopent-1-enyl)-9Hfluoren-9-ide (4). 346 mg (1 mmol) of TNF and 71 (0.5 mmol) mg of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione were dissolved in acetic anhydride (5 mL) at heating.…”

“…3 Squarylium dyes can effectively sensitize singlet oxygen generation and radical polymerization of acrylic monomers. 4,5 Croconium dyes attract attention above all due to their deep colouring and extremely high two-photon absorption cross-section. 6 They can also be used as sensitizers for photothermoplastic holography and as optical sensors.…”