1. Photoactive Fe Catalyst for Light-Triggered Alkyd Paint Curing.
- Author
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Bootsma J, Browne WR, Flapper J, and de Bruin B
- Abstract
Herein, we show that the photoactive complexes [(Cp)Fe(arene)]
+ (Cp = cyclopentadienyl; arene = C6 H6 , C6 H5 Me) act as latent catalysts that allow for photochemical control over the onset of alkyd paint curing, without the need for antiskinning agents such as the volatile 2-butanone oxime normally used to prevent curing during paint storage. The highly soluble neutral complexes [(Cp)Fe(Ch)] and [(Cp)Fe(Ch')] (Ch = cyclohexadienyl, Ch' = methylcyclohexadienyl) readily convert to the photoactive complexes [(Cp)Fe(arene)]+ upon oxidation in alkyd, allowing the latter to be dosed in a wide range of concentrations. Infrared and Raman studies show similar spectral changes of the alkyd paint matrix as have been observed in alkyd curing mediated by well-known, industrially applied cobalt- and manganese-based catalyst Co(neodecanoate)2 and [(Me3 TACN)2 Mn2 (μ-OOCR)3 ](OOCR). The [(Cp)Fe(Ch)]/[(Cp)Fe(arene)]+ system performs equally well as these cobalt- and manganese-based catalysts in terms of drying time and outperform the manganese catalyst by showing a hardness development (increase) similar to that of the cobalt-based catalyst. Based on electron paramagnetic resonance and light-activity studies, we propose that photolysis of [(Cp)Fe(arene)]+ generates short-lived active FeII species, explaining the desired latency. The [(Cp)Fe(Ch)]/[(Cp)Fe(arene)]+ alkyd curing systems presented herein are unique examples of intrinsically latent paint curing catalysts that (1) are based on an abundant and harmless transition metal (Fe), (2) do not require any antiskinning agents, and (3) show favorable performance in terms of drying times and hardness development., Competing Interests: The authors declare the following competing financial interest(s): J.B., J.F. and B.B. are inventors on PCT International Patent Application WO2021/001410 (to Akzo Nobel Coatings International B.V.), which claims the use of catalysts described in this work., (© 2022 The Authors. Published by American Chemical Society.)- Published
- 2022
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