Thermal stability of robust unsymmetrical copperporphyrins with multiple diphenylamino and nitro substituents

The syntheses and thermal stability properties of a series of amino and nitro substituted copperporphyrins are described. The thermal decomposition temperatures of the porphyrins were determined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The on-set thermal decomposition temperatures of the unsymmetrical porphyrins were found to be high in the range of 350 similar to 405 degrees C (DSC), 374 similar to 441 (TGA in air), 395 similar to 411 degrees C (TGA under nitrogen atmosphere), and 410 similar to 424 degrees C (DTA in air). Substituent dependent thermal stability trends were also studied. The trend is variable depending on the thermal analysis technique utilized. Possible reasons for such variation are discussed. These porphyrins are thermally robust even in the melamine-based sol-gel matrix. Containing 20% by weight of the substituted unsymmetrical copperporphyrin, melamine-based sol-gel showed no indication of decomposition until similar to 400 degrees C.