Sterically hindered 5,15-tetraphenylbenzene-porphyrins: syntheses, structures, atropisomerism and photophysical properties

meso -Tetraphenylbenzene (TPB) substituted porphyrin hybrids have been designed and synthesized. The meso -TPB-porphyrin hybrids exhibit two discrete atropisomers due to restricted rotation around C_meso – C_TPB bond. Both the atropisomers could be structurally characterized. The photophysical and electrochemical properties of the synthesized hybrids have been investigated with respect to tetraphenylporphyrin (TPP) and tetraphenylporphyrinatozinc(II) (ZnTPP). These hybrids exhibit reminiscent absorption and emission properties. Moreover, the redox potentials of the TPB conjugates are found to be sensitive to the meso -substituents as in the case of meso -aryl substituents. Graphical Abstract Synopsis Closest contact chromophores, namely, 5,15-tetraphenylbenzene(TPB)-porphyrin conjugates have been synthesized and structurally characterized. meso -Mesityl A_2B_2 porphyrin exists in two isomers, i.e., cis and trans conformation because of the restricted rotation about C_meso -C _TBP [C_meso = meso -positions of porphyrin and C_TBP = carbon of TBP). In spite of the isomerism, the photophysical, electrochemical characteristics were found to be similar due to negligible electronic perturbation.