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Tetra(2-cyanophenyl)porphine (ToCNPP) has been synthesized and isolated into the four respective atropisomers. The rotation of a cyanophenyl ring about the bond to the methine carbon of the porphyrin leads to interconversion reactions among the isomers. The isomerization reactions have been studied kinetically by the separation and quantitative measurement of each isomer on thin layer chromatography plates. The results show that the free energy of activation for the hindered rotation is an average of ΔG*=110 kJ/mol at 50 °C. This is the highest barrier ever measured in similar porphyrin atropisomers. The apparent interaction between adjacent cyano groups is observed. The energy of interaction is estimated to be about 2.0 kJ per mole unit of interaction.

A Cr-loaded zeolite cannot be considerably deactivated by coke deposition and can be reused for LDPE cracking without regeneration. The Cr species interact with hydroxyl groups derived from structural defects...