Modulating Charge‐Transfer Interactions in Topologically Different Porphyrin–C₆₀ Dyads

Abstract

Control over the interchromophore separation, their angular relationship, and the spatial overlap of their electronic clouds in several ZnP-C(60) dyads (ZnP=zinc porphyrin) is used to modulate the rates of intramolecular electron transfer. For the first time, a detailed analysis of the charge transfer absorption and emission spectra, time-dependent spectroscopic measurements, and molecular dynamics simulations prove quantitatively that the same two moieties can produce widely different electron-transfer regimes. This investigation also shows that the combination of ZnP and C(60) consistently produces charge recombination in the inverted Marcus region, with reorganization energies that are remarkably low, regardless of the solvent polarity. The time constants of electron transfer range from the mus to the ps regime, the electronic couplings from a few tens to several hundreds of cm(-1), and the reorganization energies remain below 0.54 eV and can be as low as 0.16 eV.

Selective Inclusion of Electron‐Donating Molecules into Porphyrin Nanochannels Derived from the Self‐Assembly of Saddle‐Distorted, Protonated Porphyrins and Photoinduced Electron Transfer from Guest Molecules to Porphyrin Dications

“…Generally, neutral porphyrin compounds, which includes free bases and metal complexes, have been recognized as electron donors in PET. [26] In contrast, cationic porphyrin complexes have been reported to act as electron acceptors. [27] The H 4 DPP 2 + moiety in the PNC is positively charged, and therefore, hard to oxidize.…”

Photophysical and Electrochemical Properties of meso,meso‐Linked Oligoporphyrin Rods with Appended Fullerene Terminals

“…[4] Subsequently, these findings were confirmed by others. [18,19] Multiporphyrin arrays, in which individual porphyrin units are linked together either by single bonds in a biaryl-type fashion or by triple fusion with formation of planar, sheetlike structures, are among the most promising scaffolds for advanced materials applications introduced in recent years. [20][21][22][23][24] Consequently, their optical and photophysical properties are increasingly being investigated.…”

Face‐to‐Face Pacman‐Type Porphyrin–Fullerene Dyads: Design, Synthesis, Charge‐Transfer Interactions, and Photophysical Studies

“…The rate constants for photoinduced electron transfer are analyzed in terms of the Marcus theory of electron transfer, which afforded a large electron coupling matrix element (V = 140 cm face arrangement have been elegantly designed and studied. Two types of dyads, namely, porphyrin-fullerene cyclophane dyads (Scheme 1a), which were synthesized independently by the groups of Diederich and Hirsch, [13] and porphyrinfullerene parachute dyads synthesized by Schuster and coworkers (Scheme 1b), [14] are well known. For the synthesis of these dyads, tethers with terminal malonate moieties were attached at the meta positions of the 5,15-phenyl rings of a tetraphenylporphyrin precursor.…”

“…These rates were found to be one or two orders of magnitude higher than those reported for a number of porphyrin-fullerene dyads in the literature. [12][13][14][15] From the CS rates, the quantum yields of the charge-separated state are estimated to be almost 100 %. The decay rate constants (k CR ) of the radical ion pairs are determined from the decay in absorbance at 1000 nm as 6.5 10 10 s À1 for 1 (Figure 6b), 5.0 10 10 s À1 for 2 (Figure 6d), and 5.2 10 10 s À1 for 3 ( Figure 6f).…”