This paper describes a series of novel benzylidene scaffold-based iodonium salt one-component photoinitiators containing double bonds and dialkylamino groups synthesized in one step via classical aldol condensation reactions. Systematic investigations of structure–activity relationships were performed via quantum-chemical calculations and experimental tests. New salts can efficiently decompose under irradiation from UV to visible regions of the spectrum. The design of new iodonium salts is described, followed by a description of properties of photoinitiators prepared in this way. All presented salts were characterized in terms of their spectral properties (UV–vis spectroscopy), ability to photodecompose (steady-state photolysis), cationic polymerization of the vinyl monomer, and epoxide monomer photoinitiation (quantum efficiency of acid generation and real-time Fourier-transform infrared measurements) as well as their proposed application in 3D printing. New benzylidene iodonium salts can photoinitiate the polymerization of vinyl ethers and epoxy monomers under LED@365 and LED@405 irradiation. Investigated compounds can simultaneously initiate and monitor the polymerization process according to the change of fluorescence during the photocuring process. Formulations before photopolymerization do not exhibit fluorescence, during the photopolymerization process fluorescence is “turning on”. This phenomenon might be used to monitor photopolymerization in an “online” manner.

This paper describes the development of four new coumarin chromophore-based iodonium salts as efficient one-component cationic photoinitiators upon light-emitting diode irradiations (LEDs) with maximum emission under the UV-A region at...

In recent years, frontal polymerisation has found a growing interest in many applications. Thus, its ability to cure thick samples with different fillers up to 50% by local application of...

High spatially resolved Raman microscopy was applied to study the early apoptosis in endothelial cells and chemical and structural changes induced by this process. Application of cluster analysis enabled separation of signals due to various subcellular organelles and compartments such as the nuclei, nucleoli, endoplasmic reticulum or cytoplasm and analysis of alterations locally at the subcellular level. Different stimuli, i.e. Fas ligand, a tumor necrosis factor, and cycloheximide, an inhibitor of eukaryotic protein biosynthesis, were applied to induce apoptotic mechanisms. Due to different mechanisms of action, the changes observed in subcellular structures were different for FasL and cycloheximide. Although in both cases a statistically significant decrease of the protein level was observed in all studied cellular structures, the increase of the nucleic acids content locally in apoptotic nuclei was considerably more pronounced upon FasL-induced apoptosis compared to the cycloheximide one. Additionally, apoptosis invokes also a decrease of the proteins with the α-helix protein structure selectively for FasL in the cytoplasm and endoplasmic reticulum.

We present a group of seven new advanced symmetric iodonium salts bearing two benzylidene-based chromophores. This is the first example of the use of a double bond in the structure of a symmetric iodonium salt. Such an improvement ensures excellent absorbing properties in the UV-A and visible range, representing a significant advance over the commonly used diaryliodonium salts. New symmetric iodonium derivatives effectively photoinitiate cationic polymerization using light-emitting diodes (LEDs) with no additives. Thus, they can act as one-component photoinitiators even in visible light, where common diaryliodonium salts remain inactive. They can be used in advanced applications such as three-dimensional (3D) VAT printing using an LCD printer. In addition, it was possible to study in detail substituent effects on the properties of the new iodonium salts due to the easily modifiable structure of the benzylidene chromophore. The research described represents a significant advance in the development of iodonium salts.