Novo complexo de Mn(II) com carbenos N-heterocíclicos como potencial fotocatalisador redox da CRP2
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Data
2023-01-25
Autores
Bignardi, Camila
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Universidade Estadual Paulista (Unesp)
Resumo
O complexo [MnII(py-mesetilmidazol)2](PF6)2 foi sintetizado a partir do NHC, pymesetilimidazol, e posteriormente caracterizado. O ligante imidazólico py-mesetil foi caracterizado por FTIR, UV-Vis, espectroscopia de fluorescência e RMN de 1H e o complexo [MnII(py-mesetilmidazol)2](PF6)2 por FTIR e UV-Vis, voltametria cíclica, MALDi-TOF e espectroscopia de fluorescência. O complexo foi ainda estudado fotofisicamente na presença dos aditivos da polimerização em 365 nm, tendo sido calculada a constante de Stern-Volmer (KSV = 0,387 M-1). Além disso, o comportamento do complexo obtido frente à irradiação em 365 nm, e sua sensibilidade ao ar também foram avaliados. O complexo sintetizado mostrou-se ativo como fotocatalisador na CRP2 do acrilato de metila (MA), utilizando α-bromofenilacetato (EBPA), como iniciador, e a trietilamina (TEA), como doadora de elétrons. Os polímeros obtidos apresentaram massas uniformes com Đ < 2. A melhor condição para a fotocatálise foi na razão molar de [MA/EBr/MnII/TEA] = 200/1/0,12/1 com Mn = 160000 g•mol‒1 e Đ = 1,4 com 73% de conversão. A mesma razão foi utilizada no acompanhamento cinético da polimerização do acrilato de metila, mostrando que o complexo além de catalisar uma reação de pseudo-primeira ordem (kobs= 2,1×10‒3 min‒1) mantém o sistema moderadamente controlado.
The [MnII(py-mesethylimidazole)2](PF6)2 complex was synthesized from the NHC, pymesethylimidazole, and further characterized. The py-mesethyl imidazole ligand was characterized by FTIR, UV-Vis, fluorescence spectroscopy and 1H NMR and the complex [MnII(py-mesethylimidazole)2](PF6)2 by FTIR and UV-Vis, cyclic voltammetry, MALDiTOF and fluorescence spectroscopy. The synthesized complex was additionally studied photophysically in the presence of polymerization additives at 365 nm, and where the SternVolmer constant (KSV = 0.387 moL-1 •L was estimated. The behaviour of the complex obtained was also monitored against irradiation at 365 nm, and its sensitivity to air. The synthesized complex was active as a photocatalyst in methyl acrylate (MA) CRP2, using αbromophenylacetate as initiator and triethylamine (TEA) as electron donor. The obtained polymers exhibited uniform masses with Đ < 2. The best condition for the photocatalysis was in the molar ratio of [MA/EBr/MnII/TEA] = 200/1/0.12/1 with Mn = 160000 g·mol‒1 and Đ = 1.4 with 73% conversion. The same ratio was used in the kinetic monitoring of the polymerization of methyl acrylate, showing that the complex, in addition to catalysing a pseudo-first order reaction (kobs= 2.1×10‒3 min‒1), keeps the system moderately controlled. Keywords: N-heterocyclic carbenes. Manganese(II). Photacatalyst. CPR2
The [MnII(py-mesethylimidazole)2](PF6)2 complex was synthesized from the NHC, pymesethylimidazole, and further characterized. The py-mesethyl imidazole ligand was characterized by FTIR, UV-Vis, fluorescence spectroscopy and 1H NMR and the complex [MnII(py-mesethylimidazole)2](PF6)2 by FTIR and UV-Vis, cyclic voltammetry, MALDiTOF and fluorescence spectroscopy. The synthesized complex was additionally studied photophysically in the presence of polymerization additives at 365 nm, and where the SternVolmer constant (KSV = 0.387 moL-1 •L was estimated. The behaviour of the complex obtained was also monitored against irradiation at 365 nm, and its sensitivity to air. The synthesized complex was active as a photocatalyst in methyl acrylate (MA) CRP2, using αbromophenylacetate as initiator and triethylamine (TEA) as electron donor. The obtained polymers exhibited uniform masses with Đ < 2. The best condition for the photocatalysis was in the molar ratio of [MA/EBr/MnII/TEA] = 200/1/0.12/1 with Mn = 160000 g·mol‒1 and Đ = 1.4 with 73% conversion. The same ratio was used in the kinetic monitoring of the polymerization of methyl acrylate, showing that the complex, in addition to catalysing a pseudo-first order reaction (kobs= 2.1×10‒3 min‒1), keeps the system moderately controlled. Keywords: N-heterocyclic carbenes. Manganese(II). Photacatalyst. CPR2
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Carbenos N-heterocíclicos, Manganês(II), Fotocatalisador, CPR2, N-heterocyclic carbenes, Manganese(II), Photacatalyst