Coronenetetraimide‐Centered Cruciform Pentamers Containing Multiporphyrin Units: Synthesis and Sequential Photoinduced Energy‐ and Electron‐Transfer Dynamics

Abstract

A series of coronenetetraimide (CorTIm)-centered cruciform pentamers containing multiporphyrin units, in which four porphyrin units are covalently linked to a CorTIm core through benzyl linkages, were designed and synthesized to investigate their structural, spectroscopic, and electrochemical properties as well as photoinduced electron- and energy-transfer dynamics. These systems afforded the first synthetic case of coroneneimide derivatives covalently linked with dye molecules. The steady-state absorption and electrochemical results indicate that a CorTIm and four porphyrin units were successfully characterized by the corresponding reference monomers. In contrast, the steady-state fluorescence measurements demonstrated that strong fluorescence quenching relative to the corresponding monomer units was observed in these pentamers. Nanosecond laser flash photolysis measurements revealed the occurrence of intermolecular electron transfer from triplet excited state of zinc porphyrins to CorTIm. Femtosecond laser-induced transient absorption measurements for excitation of the CorTIm unit clearly demonstrate the sequential photoinduced energy and electron transfer between CorTIm and porphyrins, that is, occurrence of the initial energy transfer from CorTIm (energy donor) to porphyrins (energy acceptor) and subsequent electron transfer from porphyrins (electron donor) to CorTIm (electron acceptor) in these pentamers, whereas only the electron-transfer process from porphyrins to CorTIm was observed when we mainly excite porphyrin units. Finally, construction of high-order supramolecular patterning of these pentamers was performed by utilizing self-assembly and physical dewetting during the evaporation of solvent.

High‐Yield Generation of Triplet Excited States by an Efficient Sequential Photoinduced Process from Energy Transfer to Singlet Fission in Pentacene‐Modified CdSe/ZnS Quantum Dots

“…[6, 10c, 12] According to the Fçrster energy-transfer theory,t he rate constant of the energy-transfer process is proportional to the spectral overlap between the emissiono ft he donor and absorption of the acceptor and to the inverse sixth powerofthe distance betweent he donor and acceptori napoint-to-point approximation. [13] Consequently,toachievethe efficient sequential photo-induced process from energy transfer to SF,acombinationo f semiconductor quantum dot (e.g.,C dSe/ZnS) and pentacene provides an ideal system for fulfilling an enhanced light-harvestinge fficiency throughout the solar spectruma nd ah ighly efficient conversion of the harvested light into the triplet excited states by SF.…”

A Convenient Synthesis of Pentaporphyrins and Supramolecular Complexes with a Fulleropyrrolidine

“…Consequently, these compounds are one of the most attractive building blocks for the formation of covalent or supramolecular assemblies [2,3,4,5,6]. The design and synthesis of multiporphyrin arrays is an important research topic due to their potential application as artificial light-harvesting systems [7,8,9,10,11,12,13], functional materials (near infrared dyes, electron-conducting molecular wires, nonlinear optics, molecular recognition and sensing) [14,15,16,17], and also as agents for medical imaging and photodynamic therapy [18]. Several synthetic strategies have been developed to produce multiporphyrin oligomers, including directly meso – meso -, meso – β - and β – β -linked multiporphyrin systems, oligoporphyrins with fused π-systems and arrays bearing rigid or flexible spacers.…”

Inter- and Intramolecular Electron-Transfer Reduction Properties of Coronenediimide Derivatives via Photoinduced Processes

“…When the chemical structures of coronene are compared with that of perylene, one of the advantageous points is the synthetic diversity of coroneneimide because up to four maleimide groups can be introduced to a coronene core in the case of coroneneimides, in contrast with only two maleimide groups in the case of PDI . The photophysical and electrochemical properties of coroneneimides can be accordingly controlled by the type and number of substituents. − Nevertheless, the number of reports on the photoinduced electron-transfer reduction of coroneneimides is extremely limited as compared to that of PDIs, and the detailed electron-transfer properties of coroneneimide derivatives have yet to be reported. The examination of fundamental electron-transfer properties such as reorganization energy − is therefore important for the applicative research for energy conversion and organic electronic devices. − …”