Synthesis And Optoelectronic Properties Of [60]Fullerene, Boron Dipyrromethene, Perylene And Porphyrin Derivatives

Interdisciplinarity is the research hot spot at present. Combination organic chemical synthesis with the area of material, energy and life science is the mission of organic chemists. C60, perylene (PDI) and boron dipyrromethene (BODIPY) are very useful organic molecules, they have showed attractive application prospect in nano materials, photoelectric materials, solar cells, biomedical and other fields. Thus, building a new system containing these molecules together, which can not only make full use of each system but also generate some new properties, is still a meaningful and challenging work. Molecular-scale optoelectronic integration technology is the important research directions for future information and energy technology, and the scanning tunneling microscope (STM)-induced molecular flurescence is the physical basis of it. However, only a handful of organic molecules can produce electroluminescent. When organic molecules are in contact with or near the surface of the metal, their intrinsic fluorescence will be quenched. Therefore, to get the molecular intrinsic fluorescence, the organic molecules must be physically decoupled from the metal substrate by inserting a decoupling layer. How to design a molecule that can achive self decoupling using a chemical synthesis method, is a very difficult and far-reaching work. In this dissertation, the main work is closely focused on these aspects and divided into four parts, including the direct heating reaction of C60 with amino acids and amino acid esters, rigid axial symmetrical visible light-harvesting systems:synthesis and photophysical properties of dyads and triads containing perylenebisimide and C6o, synthesis and photophysical properties of rigid axial symmetrical linear dyads and triads based on C6o, perylene and boron dipyrromethene, and design and synthesis of self-decoupled molecules based on perylene and porphyrin for molecular scale electroluminescence, respectively.1. Fulleropyrrolidines, which are generally obtained by the Prato reaction, have a wide range of applications in materials and life science. However, we found that they could also be obtained by direct heating the mixture of C60 with an amino acid or amino acid ester in the absence of aldehyde. To get insight into the reaction mechanism, we systematically studied the direct reactions of C60 with a range of amino acids and amino acid esters under the heating conditions. A possible reaction mechanism was proposed by analyzing the motifs of the reaction products. The control experiments verified the proposed mechanism.2. In this chapter, we mainly synthesized and studied the photophysical properties of rigid axial linear dyads and triads combining a perylene with one C60 unit and two C60 units respectively (C60-PDI and C60-PDI-C60). The drawback of C60 is the relatively weak absorption in the visible light region, while the absorption and emission of perylene compounds locate at the visible region at about 600 nm. Combination of C60 with perylene by a rigid structure, not only increased the absorption of C60 in the visible light region, but also made full use of the advantages of these two compounds. The steady-state and transient studies, electrochemical experiment, and theoretical calculation were carried out to compare the photophysical properties of the two rigid systems. In our system, only energy transfer was observed from PDI to C60, without forming the charge separated products. We found that the introduction of a rigid chain simplified the photophysical process, and more emission quenching of the PDI part was observed in C60-PDI-C60 with two C60 units. We also carried out the photosensitive experiments and found that photosensitizing efficiency of the two systems was basically the same, but close to or even slightly higher than that of the commercial photosensitizing agent-methylene blue.3. Based on the result of the last chapter, we continued to study the rigid axial linear systems based on C60, perylene and BODIPY molecules. In the first part of this chapter, we synthesized the rigid dyads and triads containing a perylene with one BODIPY unit and two BODIPY units, respectively (B-PDI and B-PDI-B), and investigated their photophysical properties using the steady-state absorption and fluorescence spectra, transient emission spectroscopy and electrochemical studies. In these systems, BODIPY acted as light-harvesting antenna, while the PDI as a reaction center. When BODIPY units were excited, their energy would be transferred to PDI unit to enhance the emission of PDI. Different from the previous results reported in the literature, we found that although the emission of the BODIPY unit was quenched quantitatively in both systems the fluorescence enhancement of the triad (B-PDI-B) was lower than that of the dyad (B-PDI). In the second part, we went on exploring the two rigid systems containg C60-B and C60-PDI-B, respectively.4. In the fifth chapter, we designed and synthesized the self decoupled organic molecules for STM-induced luminescence. To make these molecules achieve self decoupled on the metal surface thus to obtain the molecular intrinsic electroluminescent, we designed different tripods to separate the light-emitting group from the substrate. This chapter is divided into three parts. On the basis of the last two chapters, in the first part, we synthesized rigid systems base on perylene and BODIPY units connecting with different tripods, and carried out STM induced emission experiments. Unfortunately, we did not observe any molecular intrinsic fluorescence from these three molecules. In the second part, we designed and synthesized a tripodal porphyrin molecule, and carried out STM induced luminescence experiments. We got the molecular intrinsic fluorescence in the molecular scale. By using different sample preparation methods, we could make the molecules stand or tilt on the surface of the gold, thus offering more vertical transition moments to enhance the fluorescence. In the third part, we designed and synthesized a tetrahedal porphyrin similar to tumbler. This porphyrin can overcome the shortcomings of the tripodal porphyrin. The intrinsic fluorescence was obtained in this molecule. No matter which kind of sample deposition methods was selected, there was always a luminophore perpendicular to the gold surface leaving the other three molecules as the spacer. This molecule could achieve both self-decoupling and enhanced light emitting via the coupling of molecular transition dipole with the tip axial.