Synthesis and structure‐activity relationship of several aromatic ketone‐based two‐photon initiators

Abstract

Several novel aromatic ketone-based two-photon initiators containing triple bonds and dialkylamino groups were synthesized and the structure-activity relationships were evaluated. Branched alkyl chains were used at the terminal donor groups to improve the solubility in the multifunctional monomers. Because of the long conjugation length and good coplanarity, the evaluated initiators showed large two-photon cross section values, while their fluorescence lifetimes and quantum yields strongly depend on the solvent polarity. All novel initiators exhibited high activity in terms of two-photon-induced microfabrication. This is especially true for fluorenone-based derivatives, which displayed much broader processing windows than well-known highly active initiators from the literature and commercially available initiators. While the new photoinitiators gave high reactivity in two-photoninduced photopolymerization at concentration as low as 0.1% wt, these compounds are surprisingly stable under one photon condition and nearly no photo initiation activity was found in classical photo DSC experiment.

Visible light sensitive photoinitiating systems: Recent progress in cationic and radical photopolymerization reactions under soft conditions

“…The fluorenone derivative h-B3FL (a parent derivative is encountered in two-photon induced polymerization [215,216]) is another suitable push-pull dye usable at 532 nm (ε 532nm ∼ 10,800 M −1 cm −1 ) and efficient as part of a h-B3FL/MDEA/R -Cl PIS (FRP of TMPTA); final conversion of ∼54% (see Table 9) [198].…”

Evidence of concentration dependence of the two-photon absorption cross section: Determining the “true” cross section value

“…Three different two-photon initiators (2PIs), 2,7-bis((4-(dibuty lamino)phenyl)ethynyl)-9H-fluoren-9-one (B3FL), (2E,6E)-2,6-bi s(4-(dimethylamino)benzylidene)-4-methylcyclohexanone (M2CMK) and (2E,5E)-2,5-bis(4-(dibutylamino)benzylidene)cyclo pentanone (B2CPK) [17,18] were used for this study. Fig.…”

Efficient Excited‐State Symmetry Breaking in a Cationic Quadrupolar System Bearing Diphenylamino Donors

“…The development of organic materials displaying high twophoton absorption (2PA) has recently attracted great interest due to variousp otential applications [1,2] in photonics and optoelectronics, such as three-dimensional optical datas torage, [3,4] multiphoton microfabrication, [5][6][7] fluorescence imaging, [8,9] photodynamic therapy, [10,11] and opticalp owerl imiting, [12] among others. Chromophores with strong 2PAa re desired for all these applicationsf or the remarkable advantages of the two-photon over the commono ne-photon excitation (the former allowing ab etter focalisation)a nd of employing the less energetic andm ore penetrating infrared radiation with respect to the common ultraviolet-visible light.…”