Photoswitching of ortho-Aminated Arylazopyrazoles with Red Light

Bidirectional photoswitching of arylazopyrazoles with visible light is enabled by substitution with pyrrolidine and piperidine in the ortho-position of the phenyl ring. The absorption maxima were red-shifted and the molar absorption coefficients in the visible range increased significantly, allowing the use of blue light (lambda = 465 nm) for the E -> Z isomerization and red light (lambda = 600 nm) for the Z -> E isomerization. N-Methylation of the pyrazole leads to an excellent thermal stability of the Z isomer.

Automated summary

The bidirectional photoswitching of arylazopyrazoles with visible light is achieved by incorporating pyrrolidine and piperidine in the ortho-position of the phenyl ring, leading to red-shifted absorption maxima and increased molar absorption coefficients. This allows for E -> Z isomerization with blue light (λ = 465 nm) and Z -> E isomerization with red light (λ = 600 nm). N-methylation of the pyrazole results in excellent thermal stability of the Z isomer.