β-pyrrole substituted porphyrin–pyrene dyads using vinylene spacer: Synthesis, characterization and photophysical properties

Abstract

We have designed and synthesized donor-acceptor conjugates having donor pyrene at the pyrroleβ position of either free-base porphyrin or Zn(II) porphyrin using vinylene spacer. Both the dyads have been completely characterized by elemental analysis, MALDI-MS, UV-Vis., and fluorescence (steady state and timeresolved) spectroscopies as well as cyclic voltammetry. The absorption maxima of both dyads are red-shifted by 8-12 nm. The ground state properties showed that there exist minimum π-π interaction between the aromatic subunits of these D-A systems. Quenched emission was observed in both the dyads when excited at 290 nm. The quenched emission explained in terms of intramolecular excitation energy transfer competes with the photo-induced electron transfer reaction in these D-A system.

Synthesis, Electrochemical and Photochemical Studies on π‐Extended Mono‐β‐Functionalized Porphyrin Dyads

“…Zn monoformyl porphyrin was subjected to Horner‐Wadsworth‐Emmons reaction with stabilized phosphonates and give porphyrin dyads in good to excellent yields. There were many reports published on the Wittig reaction of formyl porphyrins and the synthesis of 1 , 1 a , 4 and 4 a porphyrin dyads were already reported by these synthetic routes ,. The main drawback of these methods were multistep synthesis of formyl porphyrin into phosphonium salt where formyl group need to be transformed into phosphonium derivative that involved the synthesis of 2‐hydroxymethyl and 2‐chloromethyl porphyrin derivatives .…”

“…The presence of chromophore group such as anthracene and pyrene, the intramolecular EET can be expected in 3 , 4 , 3 a and 4 a porphyrin dyads where energy transfer occurs from the donor chromophores to acceptor porphyrin core. There are many reports available on EET mechanism in anthracene/pyrene‐porphyrin donor acceptor systems in literature,,, whereas in these type of systems, anthracene and pyrene moieties mainly attached at meso /axial position of the porphyrin core. Very few reports have been published on β ‐substituted donor‐acceptor porphyrin systems ,.…”

“…The position of donor moiety in a porphyrin dyad can greatly affect the electronic coupling between the component units which results in quite different mechanism and rates . The synthesis of covalently linked β ‐porphyrin dyads with high fluorescent chromophores such as anthracene, pyrene and phenothiazine is largely unexplored ,. Officer and his coworkers reported energy transfer process in many porphyrin containing hetero‐dyads connected at β ‐pyrrole positions via ‐conjugated bridges .…”

Triphenylamine corrole dyads: Synthesis, characterization and substitution effect on photophysical properties

“…All these experiments were performed with 1 mM concentration of compounds in dichloromethane at a scan rate of 100 mV s −1 in which tetrabutylammoniumperchlorate (TBAP) was used as a supporting electrolyte, standard calomel as reference electrode, glassy carbon as working electrode and Pt-wire as counter electrode. 43…”

Flexible Tuning of Unsaturated β‐Substituents on Zn Porphyrins: A Synthetic, Spectroscopic and Computational Study

“…b-Substitution is knownt oc ause ar edshift of the Bb and, and as maller redshift of the Qb ands. [2,11,[21][22][23][24] As tudy in which the substituent and the substitution position( meso or b)i s varied suggests that the redshift in absorption is influenced more by the substituent extending conjugation (ethynyl linker caused further redshifting) while the broadening of the Bb and was influenced more by the position (b broader than meso). [25] Here the positiono ft he Bb and shows some variation with R'/ R'',a nd this also has some effect on the band broadness, as all are substituted at the b-position.…”