Tesis sobre el tema "Extended porphyrin"

Porphyrins with extended π-electronic networks are promising candidates for a wide range of applications from medicine to nanotechnology owing to their unique optical and electronic properties. This dissertation is focused on synthesis, characterization and application of β-functionalized π-extended porphyrins. This dissertation is comprised of seven chapters. Chapter 1 focuses on the importance and objective of this work. Chapter 2 gives brief introduction to porphyrins and π-extended porphyrins. In chapter 3, a class of β-functionalized linear push-pull zinc dibenzoporphyrins YH1-YH3 were designed, synthesized, and utilized as light harvesters for DSSCs. In chapter 4, in order to further enhance the photovoltaic performance of β-functionalized benzoporphyrin dyes based DSSCs, a new class of push-pull dibenzoporphyrins YH4-YH7 bearing the phenylethynyl bridge was designed, synthesized and utilized as light harvesters for DSSCs. In chapter 5, in order to solve the photodegradation problem associated with YH7, a new series of push-pull dibenzoporphyrins YH8-YH10 bearing different diarylamino push groups was designed and synthesized. This class of push-pull porphyrins shows improved photostability and enhanced DSSC performance. In chapter 6, a new pentacene-fused diporphyrin with high stability and solubility was prepared and characterized. Chapter 7 includes the summary of this dissertation and describes possible future work.

Porphyrins offer a very synthetically flexible template which can be modified in numerous ways to synthesize molecules with very useful properties applicable in areas such as non-linear optical properties, photodynamic therapy, dye-sensitized solar cells, chemical sensors and organic electronic devices. β-Substituted π-extended porphyrins offer unique capabilities in tuning the properties of the molecule towards practical applications. Increased π-conjugation allows the HOMO-LUMO gap to decrease and hence to redshift the absorption into the near-IR region. β-Fused benzoporphyrins offer additional benefits in which the benzene ring itself can be further modified using electron donating substituents and electron donating substituents to electronically tune these porphyrins for various uses. The goal of the research pursued in this dissertation was to develop new methods for the development of β-Substituted π-extended porphyrins and to study their optical and electronic properties. To accomplish this goal, we developed new method to synthesize A2B2 type tetrabenzoporphyrins and we studied the electron transfer in such systems. We also studied the effectiveness of such systems in dye sensitized solar cells. A new method to synthesize functionalized naphthalene fused porphyrins was also developed and we were also able to use this method to synthesize a push-pull naphthalene fused porphyrin.

Ce mémoire s'articule autour de deux aspects complémentaires des processus qui accompagnent le transfert d'électron. Le cœur de ce projet concerne la valorisation de l'électrochimie moléculaire comme technique d'activation dans deux directions : activation de processus mécaniques ou de mouvements moléculaires dans des architectures commutables pour lesquelles un transfert d'électron fournit l'impulsion tout en permettant le contrôle et la lecture de l'état d'un système dynamique, et activation de processus chimiques pour lesquels l'électrochimie est exploitée en ingénierie moléculaire pour élaborer des molécules complexes et proposer une alternative efficace aux méthodes classiques de la synthèse organique. Le fil conducteur « activation électrochimique » est déroulé autour deux grandes classes de composés : les -dimères de dérivés du viologène et les macrocycles conjugués à base de pyrrole. Dans la première partie de ce mémoire, nous présenterons nos résultats en matière de systèmes moléculaires commutables dont les mouvements intramoléculaires et les propriétés sont activés et contrôlés par simple transfert d'électron tandis que la deuxième partie est centrée sur l'ingénierie électrochimique de porphyrines étendues
One of the most important key to the development of nanosciences lies in our ability to monitor, modify or control nanometric materials. The addition or removal of electrons to or from given molecular objects can find useful applications in numerous arena of nanosciences: as signal transcription of interactions processes, as impulse to trigger conformational, configurational or directional mechanical changes at the molecular level or even as a way to control and activate the reactivity of molecular building blocks in organic synthesis. This work deals with two complementary processes associated to electron transfer: molecular movements in switchable architectures and activation of molecular building blocks to form conjugated macrocyclic structures The first part of this research work is devoted to the synthesis of porphyrin-based molecular tweezers and of ferrocene-based molecular pivots. The dynamic properties of these switchable molecular objects; relying on reversible π-dimerization processes, have been investigated by spectroscopic, electrochemical and spectroelectrochemical methods. In the second part of this manuscript we show few examples of electrochemically driven synthetic procedures for preparation of expanded porphyrins. Unlike chemical oxidants, which must often be tested empirically for a given transformation, under electrochemical conditions, one has the opportunity to tune the reactivity of the pyrrole-based reagent via the choice of anodic voltage. We especially established that the use of bipyrrole allows for the clean and high-yield production of cyclo[8]pyrrole; the requisite electrochemically-induced cyclization of four bipyrrole building blocks likely involving an electrolyte-based templating effect. The success of this approach leads us to propose that analogous electrochemical oxidation processes could be used to generate a range of new expanded porphyrin products

The fascinating role that porphyrins play in natural processes such as photosynthesis and respiration, continues to provide a compelling motivation to study these chromophores and to design new analogues with improved functions. This dissertation describes the interdisciplinary study of several classes of compounds that include π-extended porphyrins, expanded porphyrins, porphycenes, polypyrroles and porphyrins. Dictated by the need to capture efficiently red and near-infrared light, the so-called π-extension approach has been established as a powerful tool in the synthesis of large aromatic chromophores. Many of these artificial systems demonstrate properties similar to natural porphyrins. Often, however, a reduced bandgap is seen due to a greater π-system. Synthetic challenges associated with the preparation of the linearly annulated porphyrins have long been recognized. Many of these have now beed overcome as the result of a newly developed synthetic protocol described in Chapter 1. This protocol allows for the synthesis of a pyrrolic building block under milder conditions. As a continuation of this work, naphthobipyrroles were obtained via the π-extension strategy applied to a benzobipyrrole. The utility of this new building block was demonstrated with the syntheses of an electrochromic polynaphthobipyrrolic polymer (Chapter 3) and a dinaphthoporphycene (Chapter 2), a chromophore isomeric to porphyrin. Chapter 4 describes a different approach to porphyrin functionalization. Here, the goal was to effect substitution at the so-called β pyrrolic positions with using two bithiophene groups. Although, the resulting product is not completely rigid, enhancement in the sensitizing properties of the basic porphyrin chromophore was seen in a dye sensitized solar cell (DSSC) assembly, as studied by scanning electrochemical microscopy (SECM). The synthetic contributions concerning this work, carried in collaboration with Bard group, are expected to lay the groundwork for the development future photovoltaic materials. Expanded porphyrins are the more diverse group of porphyrinic derivatives. In effort to develop new conjugated expanded porphyrin systems and to understand their spectroscopic behavior in greater detail, a set of expanded porphyrins, based on the direct electrochemical oxidation of terpyrrole-like fragments, was developed in conjunction with the Bucher group (Grenoble, France). This effort is described in Chapter 5. Specifically it is shown that trithiacyclo[9]pyrrole may be prepared by means of an electrochemical synthesis.
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碩士
臺灣大學
化學研究所
95
To synthesize a conjugation system of porphyrins and to study their properties with metal ions are the major work of this thesis. With the assists of microwave technology, the target molecule was easily achieved. In the presence of the diketone porphyrin with 5,6-diamino-1,l0-phenanthroline in a co-solvent system (CH2Cl2:Et2O: MeOH:H2O) proceeded smoothly to yield the p-diketoone prophyrin (A9). Complexation of A9 with various metal ions were investigated. In a typical example, reaction of CoCl2 with A9 in the DMF, produced a metal-prophyrin species C1. This cobalt prophyrin complex can be used as a catalyst in oxidation olefin, benzaldehydes and sulfides under mild conditions.

碩士
國立中興大學
化學系所
101
Energy is the prime need of human being but their sources is limited in nature. So, the development of alternative clean and renewable energy sources is a priority in the research field to solve the problem of energy shortages and green house effect. Among numbers of alternative energy, infinite and inexhaustible solar energy is a good candidate to meet a rapidly increasing global demand for energy. Recently, the development of solar cells especially to the third generation solar cells is dye-sensitized solar cells (DSSC). DSCC are currently attracting considerable attention because of their high light-to-electricity conversion efficiencies, ease of fabrication, and low production costs. However, we focused on application of DSCC especially for dye design that is based on porphyrin structure. In addition of porphyrin monomers as dyes, we have synthesized a series of porphyrin dimers due to their wider Soret band and Q band caused by exciton coupling. Moreover, the increasing of extinction coefficient and bathochromic shift in absorption spectrum is also notable application for porphyrin dimers. We expect these advantages are useful in DSCC. Therefore, we designed and successfully synthesized various of π-extended push-pull porphyrin dimers by single bond or ethynyl group as linker to combine two porphyrin monomers. In addition, we are also committed to study device for dye-sensitized solar cells, hope that we can get achievements well in the future.

碩士
國立臺灣大學
化學研究所
96
The major work of this thesis involves the synthesis of a series of extended conjugation bimetallic porphyrin complexes and the study of electronic effect on catalytic activities. The target ligand (H2TPP-Phen) was prepared by extension of conjugation through coupling with 1,10-phenatroline moiety. First, H2TPP was metallated with copper ion, followed by the nitration at β-pyrrole position to give β-NO2-CuTPP in good yields. De-metallation of β-NO2-CuTPP and subsequent reduction of nitro group into amino group β-NH2-H2TPP in the presence of tin(II) chloride and HCl proceeded smoothly. Under oxygen and photo conditions, the desired diketo-porphyrin H2TPPO2 was formed by oxidation. Finally, H2TPP-Phen was established by the condensation of H2TPPO2 and diamino-1,10-phenatroline in presence of trifluoroacetic acid. The metal complexes were prepared via the complexation with the desired metal ions. Catalytic oxidations of alkene and sulfide by a series of cobalt complexes such as CoTPP-PhenCoCl2, ZnTPP-PhenCoCl2 and CoTPP-Phen were investigated. In the epoxidation, all of the three cobalt complexes showed good catalytic activities, indicating that the cobalt ions in the coordination mode either in a porphyrin moiety or in a phenatroline site remained the same activity. Surprisingly, only the ZnTPP-PhenCoCl2 could catalyze the oxidation of a sulfide to form sulfoxide. In a detailed finding, the oxidation was through the singlet oxygen, which was produced by the irradiation of visible light of ZnTPP-PhenCoCl2 in the air. In other words, the zinc porphyrin complex can act as a photosensitizer to help the generation of singlet oxygen. Furthermore, a series of palladium complexes (MgTPP-PhenPdCl2, CoTPP-PhenPdCl2, NiTPP-PhenPdCl2, CuTPP-PhenPdCl2 and ZnTPP-PhenPdCl2) were prepared by a similar manner. The catalytic behaviors of these complexes toward Heck and Suzuki-Miyaura reactions were also investigated. In the Heck reaction, these palladium complexes showed different activities. In fact, ZnTPP-PhenPdCl2 appeared to be the most active, whereas CoTPP-PhenPdCl2 illustrated to be the least active. In Suzuki-Miyaura coupling reaction, the ZnTPP-PhenPdCl2 still remained to be the most active one.

碩士
國立中興大學
化學系所
100
Dye-sensitized solar cells (DSCs) are currently attracting considerable attention because of their high light-to-electricity conversion efficiencies, ease of fabrication, and low production costs. The sensitizer, which harvests the solar radiation and converts it to electric current, is one of the key components of DSCs. Ruthenium complexes are renowned for its remarkable efficiency and stability in DSCs. They play an important role in DSCs in the past twenty years. But ruthenium is rare metal at the cost of high price. We devoted to synthesizing porphyrins owing to the high light harvesting efficiency and strong absorption and emission in the visible region. Compared to ruthenium sensitizers, the porphyrin sensitizers are more eco-friendly and much easily to obtain. Therefore, porphyrins are superior to other organic or ruthenium dyes. Our recent studies of a push-pull porphyrin YD2-o-C8 show that the power conversion efficiency (PCE) of the DSCs device using cobalt-based electrolyte attained to 12.3 % when co-sensitized with an organic dye Y123. We found that the photovoltaic performance of zinc porphyrins can be improved by expanding π system to increase the light-harvesting efficiency. Although the photovoltaic performance of DCSs can be enhanced by wrapping porphyrin core with long alkoxyl chains, we examine the effects of different push-pull substituents. A series of porphyrin sensitizers with ethyne-linker were synthesized including YD20、YD21、YD22、YD23、YD24、YD25、GY16、GY32、GY33、GY34、GY44、GY45、GY46、GY47、GY48 by Sonogashira cross-coupling method. The DSCs devices constructed using YD23 and YD2-o-C8 dyes reach similar PCE (9.00% vs 9.01%). It is worth noting that the PCE of YD24 exceeded YD2-o-C8. We believed that extension of π-conjugation of the molecules plays a key role to increase the light-harvesting ability, and hence the efficiency. To further increase the hydrophobic environment of TiO2 and block the approach of electrolyte, we employed butyloctyl (BO) long alkyl chains instead of octyl groups at the meso-phenyls. The initial tests show that GY32 is the best performing sensitizer in this series of porphyrins. GY32 not only provided outstanding cell performance (10.28%) but also easily manufactured. In other words, porphyrin molecules offer immense potential as the light harvesting component of DSCs.

碩士
國立中興大學
化學系所
102
We have successfully prepared of π-extended mono - and di - porphyrins dyes for Dye-Sensitized Solar Cells. For mono porphyrins, we synthesized porphyrin dyes RLC1, RLC2 with double bond electron-withdrawing group on meso position of the porphyrin, and diarylamine as an electron-donating group at the oppsite meso position of the porphyrin. We found that the porphyrin with cyanoacrylic acid group (RLC2), has a more red shift phenomena in the absorption spectra due to the interaction electronic between the porphyrin ring and anchor group, the efficiency of the corresponding device is 5.79%.. As to the porphyrin dimers, we successfully synthesized porphyrin dyes with different donating - and withdrawing-electron groups, e.g.,RLC3, RLC4, RLC5, RLC6, RLC7 and RLC8. Because porphyrin dimers show exciton or electronic coupling, the Soret band and Q-band become broader, witch increased extension coefficient, and UV-vis spectra show significant red-shift, therefore it improve the of light-to-electron efficiency. Among these compounds, RLC6 has the highest efficiency, (PCE=10.07%). RLC5 exhibited very wide UV-vis absorbance spectrum extending toward the near infrared region which is suitable for co-sensitization to achieve panchromatic absorption.

碩士
國立中興大學
化學系所
104
Energy is closely linked to economic development. Due to the rise of oil crisis and environmental awareness, it is crucial to use green energy. The solar energy has great potential for development and the research in Dye-sensitized Solar Cell (DSCs) is becoming an important target for investment. The thesis mainly focus on the synthesis of a series of novel push-pull porphyrin dyes for application in DSCs. The porphyrin dyes consist of two phenyl groups which attached at 5th,15th -meso-position, bearing two 2-hexyl-dodecyloxy (OHD) groups as core units, the ethynylene group bridged between electron-donating group and core units, and the pyridine- 2,6-dicarboxylic acid as an electron-withdrawing/anchoring group. We expect the design of the porphyrins with branched alkyl group and high numbers of carbons could increase the solubility, prevent molecules from aggregation, and effectively decrease the quantity of yielding dark-current.In addition, the bonding force between dyes and TiO2 could strengthen owing to the pyridine-2,6-dicarboxylic acid. At present, we used the porphyrin dyes for testing in DSCs, SY4 used a benzenecarboxylic acid as an electron acceptor gives the best power conversion efficiency of 6.19 %. In the future, we will pursue the optimal conditions of each dyes for use in Dye-sensitized Solar cell (DSCs), it is desirable to get as much efficiency as possible.

碩士
國立中興大學
化學系所
102
We successfully synthesized a series of znic porphyrins H1 to H18 based on D-π-A structure. It is divided into three parts. (1) There is two phenyl groups attached at 5th, 15th-meso-positions, bearing two dodecoxyl (-OC12H25) chains at the ortho-position of each phenyl group to decrease the dye aggregation and retard the touch between electrolyte and TiO2 surface. We proposed the use of pyridine derivatives as electron -withdrawing and anchoring group in place of a conventional carboxyl group, denoted as H4, H5, H6, H7, H8, H9, H10 and H11. From the FT-IR spectra, We proposed that the bonding model between dye and TiO2 surface. We also study their absorption spectra, electrochemical properties, and photovoltaic properties. The overall efficiencies of DSSCs based on H5, H6 and H9 are all more than 8 %, and Jsc is higher than YD2-o-C8, which using the carboxy group as anchoring group in the same condition.(2) To control the distance between the porphyrin core and the anchoring group, we utilize a acenyl-ethynyl group as a bridging moiety to connect a meso position of porphyrin and the carboxylic acid end, denoted as H1, H2, H13 and H14 on the basis of YD2-o-C8 structure. But the efficiency of power conversion of these devices decreased systematically with increasing length of the link. Besides, acenes are put between porphine core and carboxylic anchoring group as the secondary chromophores in order to broaden porphyrin absorption bands, denoted as H13, H14, H15 and H17. Among those porphyrins, the benzothiadiazole -functionalized porphyrin (H17) exhibit the best performance. (3) On the basis of GY50 structure, the porphyrin sensitizers H16, H17 and H18 are designed and synthesized. The role of benzothiadiazole and bridging moiety in the structure are investigated which according to photovoltaic properties.