Synthesis and properties of β-arylated triphyrins[2.1.1] by successive introduction of one to six aryl groups at the β-pyrrole carbons

The β -arylated meso -tetra( p -tolyl) triphyrins[2.1.1] containing two, three, and four p -fluorophenyl groups were synthesized by reacting appropriate β -bromo triphyrin[2.1.1] with p -fluorophenyl boronic acid in toluene/THF/H 2 O (1:1:1) at 80 ο C for 8 h–12 h and their properties were compared with our previously reported β -arylated triphyrins[2.1.1] containing one and six p -fluorophenyl groups. The increase of the number of p -fluorophenyl groups at the β -pyrrole carbons induces steric hindrance at the periphery of triphyrin[2.1.1] that results in the alteration of electronic properties due to distortion in the macrocycle which is reflected in their structure, spectral and redox properties. The X-ray structure analysis revealed that β -di( p -fluorophenyl) meso -tetra( p -tolyl) triphyrin[2.1.1] was almost planar like meso -tetra(phenyl) triphyrin[2.1.1] whereas the β -hexa( p -fluorophenyl) meso -tetra( p -tolyl) triphyrin[2.1.1] was significantly distorted. The absorption spectra of β -arylated triphyrins[2.1.1] showed bathochromically shifted Soret and Q-bands with reduction in absorption coefficients and increase in the bandwidth compared to the β -unsubstituted meso -tetra( p -tolyl) triphyrin[2.1.1] and the maximum effects were noted for β -hexa( p -fluorophenyl) meso -tetra( p -tolyl) triphyrin[2.1.1]. The β -arylated meso -tetra( p -tolyl) triphyrins[2.1.1] are stable under electrochemical conditions and DFT/TD-DFT studies are in agreement with the experimental observations. The β- arylated triphyrins[2.1.1] were synthesized and the effect of step-wise increase of one to six p -fluorophenyl groups at the β -pyrrole carbons of triphyrins[2.1.1] on structure, spectral, and redox properties of triphyrins[2.1.1] was studied. • Synthesized β -arylated meso -tetra(p-tolyl) triphyrins by adding p -fluorophenyl groups. • Adding p -fluorophenyl groups at β -pyrrole carbons increases steric crowding and alters properties. • β-Arylated meso-tetra(p-tolyl) triphyrins are stable under electrochemical conditions.