A green one-pot shortcut to light switching Tröger base analogs

Optimized desublimation of 2,4-diaminotoluene (4-methylbenzene-1,3-diamine) formed its ultrapure crystals. The collected crystals were analyzed by X-ray crystallography and then directly consumed in a condensation reaction with paraformaldehyde that resulted in the formation of Hünlich’s base. The subsequent one-pot diazotization and coupling reactions produced a new bisazo analog of Tröger’s base in the maximum possible compliance with the principles of green chemistry. The obtained bisazo product was found to be a durable and affordable building block suitable for use in the design of light-driven molecular machines.