β‐Trisubstituted “Push–Pull” Porphyrins – Synthesis and Structural, Photophysical, and Electrochemical Redox Properties

Abstract

A family of tri--substituted porphyrins, MTPP(CH 3 ) 2 X (M = 2H, Co, Ni, Cu and Zn; X = NO 2 or CHO; TPP = tetraphenylporphyrin), was synthesized and characterized by various spectroscopic techniques. The single-crystal X-ray structures of NiTPP(CH 3 ) 2 CHO and H 2 TPP(CH 3 ) 2 NO 2 revealed ruffled and saddle conformations of the porphyrin core, respectively. The effects of the substituents were reflected in bathochromic shifts of the electronic spectral features and positive or negative [a] 3269 shifts of the redox potentials. H 2 TPP(CH 3 ) 2 NO 2 and H 2 TPP(CH 3 ) 2 CHO exhibited very high dipole moments (5.76-7.59 D) compared with that of H 2 TPP (0.052 D) owing to the push-pull effect. These push-pull porphyrins exhibited lower HOMO-LUMO gaps than those of MTPP(NO 2 ) and MTPP. The redox tunability was achieved through the introduction of electron donor and acceptor groups at the porphyrin backbone. Full PaperCu II , and Zn II complexes (1a-2d, Figure 1) using appropriate metal salts. In addition, we explored their structural, photophysical, and electrochemical redox properties.

β‐Heptasubstituted Porphyrins: Synthesis, Structural, Spectral, and Electrochemical Properties

“…The saddle conformation was further confirmed by a shorter Co–N bond length (1.92 Å), longer C β –C β (1.43 Å) bond length, and increased C β –C α –C m bond angles with an associated decrement in N–C α –C m bond angles (Table ). The displacement of β‐carbons from the mean plane (Δ C β ) was found to be 0.921 Å, whereas the displacement of 24 core atoms from the mean plane (Δ24) was 0.482 Å, which was significantly higher than that of H 2 TPP and H 2 TPP(NO 2 )(Me) 2 (Δ24 = 0.208 Å) …”

“…Recently, our group has developed a simple methodology for the synthesis of tri‐β‐substituted push–pull porphyrins . Herein, we developed a facile synthetic route to obtain the β‐hepta‐substituted porphyrins.…”

The spectroscopic impact of interactions with the four Gouterman orbitals from peripheral decoration of porphyrins with simple electron withdrawing and donating groups

“…11 The β-substitution in push-pull porphyrins is an attractive synthetic approach to destabilize the specific orbitals to achieve the desired red-shifted Q band and introduce a strong dipole moment. 7,26,[37][38][39] By studying a series of Zn porphyrins, 1-4, synthesized with combinations of simple electron withdrawing and electron donating groups on the β-position, we used MCD spectroscopy to probe the differences in their electronic structure. The computational aspects are vital for the design of effective photosensitizers because electron charge transfer is a necessary property and arises from an unequal electron distribution on MOs as a result of differential substitution.…”

Synthesis and the spectral, electrochemical, and nonlinear optical properties of β-dicyanovinyl-appended ‘push–pull’ porphyrins

“…21,22 Recent advancement in the amplification of third-order NLO coefficients is discussed herein. Synthesis of penta(zincporphyrin) [60]fullerene for good optical limiting property by B. Kulyk et al 23 Looped covalently bonded Anderson-type polyoxometalateporphyrin hybrids were synthesized by Hafiz Muhammad Asif et al for enhancement in optical nonlinearity. 24 Zhiwei Liu et al have reported an ether-linked porphyrin covalent organic framework for optical switching.…”