Synthesis And Characterization Of Fullerene-Corrole-New Electron Transfer Dyads

With the development and popularization of electronics and information science, higher and higher request is proposed about the material. Organic photovoltaic materials in solar cells are a new challenging field that is quickly developing in chemistry. So far, a series of covalently linked materials were synthesized to simulate the energy transfer process in the nature of photosynthesis. To properly understand the photophysical properties of the conjugated molecular systems is of great significance.In recent years, functionalized fullerenes had become one of the most important materials in the design of new optoelectronic devices. Due to the symmetrical structure and specialπ-electron system, fullerenes have a smaller reorganization energy and a strong ability to accept electrons, which could accelerate electron transfer (ET) and slow down charge recombination (CR), resulting in the formation of long-lived charge separation states. As an important building block, C60were widely used in the past research. However, other fullerenes were seldom used as the electron acceptors which might behave differently from the C60derivatives.In this thesis, we synthesized three new corrole-base D-A systems with different fullerenes as the electron acceptors. The structures, the energy levels, the gibbs free energys and electron transfer rate constants were investigated.1. The fullerene-corrole dyads with three different electron acceptors (C70, C84and Gd@C82) were prepared by the1,3-dipolar cycloaddition reaction. The materials were separated by HPLC separation. HPLC, MALDI-TOF-MS, UV-Vis-NIR, and1HNMR gave the confirmation that the fullerenes molecule had been attached to the corroles.2. The properties of the three new D-A systems were analyzed with UV-Vis-NIR, fluorescence spectroscopy, time-resolved fluorescence decay spectroscopy, electrochemistry, nanosecond transient absorption spectroscopy method. By comparing the UV-Vis-NIR spectra of the three dyads, we found that the stokes bands and Q zones of corrole absorption appeared, but was blue-shifted compared with that for the reference corrole. The new bands at around300nm corresponded to the fulleropyrrolidine entity, indicating that fullerenes had been chemically attached to corrole. Steady-state fluorescence spectra showed that the emissions of corrole was efficiently quenched in the dyads, indicating the intramolecular electron transfer reaction between fullerenes and corrole, but the quenching efficiency was different (C60-C70>C84>Gd@C82). The redox properties of fullerene-corrole dyads were studied by cyclic voltammetry. Compared with the reduction potentials of the fullerene monomers, significant negative shift of the first reduction and the first oxidation occured, Therefore, a strong interaction between corrole and fullerenes in the dyads was suggested.-△G of the three dyads obtained by electrochemical data calculation was greater than zero, indicating that the electron transfer reaction processes were spontaneous and thermodynamically allowed. The electron transfer of C70-corrole was confirmed by nanosecond transient absorption spectrum. However, we did not capture the charge separated state of C84-corrole and Gd@C82-corrole, which might be due to the shorter lifetime.