Conjugated Polymer Synthesis and Materials Applications
Description
- Living conjugated polymers
- Cyclophane conjugated polymers
- P- and As-containing conjugated polymers
- Low bandgap conjugated polymers
- 3-D and helical conjugated polymers
- Conjugated polymers for organic solar cells and organic electronic devices
Keywords: Conjugated polymers, transition metal catalysis, living polymerization, polycondensation, optical materials, electrical
materials, magnetic materials, biomedical materials
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Content
1 TRANSITION-METAL-CATALYZED POLYCONDENSATION
1.1 Introduction
1.2 Ni-Catalyzed Polycondensation
1.3 Pd-Catalyzed Polycondensation
1.4 Pd-Catalyzed Polycondensation via C-H Bond Functionalization
1.5 Cu- and Fe-Catalyzed Polycondensation
1.6 Other Transition-Metal-Catalyzed Polymerizations
1.7 Summary
2 LIVING CONJUGATED POLYMERS
2.1 Introduction
2.2 Metal Pi-Binding in CTP
2.3 Common Catalysts in CTP
2.4 Kumada-Corriu Catalyst-Transfer Polycondensation (KCTP)
2.5 Murahashi Catalyst-Transfer Polycondensation (MCTP)
2.6 Negishi Catalyst-Transfer Polycondensation (NCTP)
2.7 Suzuki-Miyaura Catalyst-Transfer Polycondensation (SMCTP)
2.8 Stille CTP
2.9 Buchward-Hartwig Amination and Direct Arylation Polymerization (C-H Activation)
2.10 Chain-Growth Polymerization of Aromatic without Metals
2.11 Conclusions
3 OPTICALLY ACTIVE THROUGH-SPACE CONJUGATED POLYMERS BASED ON PLANAR CHIRAL [2.2]PARACYCLOPHANE
3.1 Introduction
3.2 Through-Space Conjugation of [2.2]Paracyclophane-Based Conjugated Polymers
3.3 Optically Active Through-Space Conjugated Polymers Based on Planar Chiral [2.2]Paracyclophane
3.4 Optically Active Through-Space Conjugated Cyclic Oligomers Based on Planar Chiral [2.2]Paracyclophane
3.5 Conclusion
4 DEVELOPMENT OF SOLID-STATE LUMINESCENT CONJUGATED POLYMERS CONTAINING BORON ELEMENT-BLOCKS AND THEIR APPLICATIONS
4.1 Introduction
4.2 Boron Ketoiminates
4.3 Rational Design for AIE-Active Molecules Based on Excitation-Driven Complexes
4.4 AIE-Active Materials Having NIR Luminescent Properties
4.5 Conclusion
5 ARSENIC-CONTAINING CONJUGATED POLYMERS
5.1 Introduction
5.2 Arsenic in Organic Compounds
5.3 As-C Bond Formation
5.4 Arsenic-Containing ¿-Conjugated Systems
5.5 Poly(vinylene-arsine)s
5.6 Arsole Polymers
5.7 Pi-Conjugated Polymers with Other Arsenic Units
5.8 Conclusions
6 CARBORANE-CONTAINING CONJUGATED POLYMERS AND THEIR APPLICATIONS FOR OPTOELECTRONIC MATERIALS
6.1 Introduction
6.2 Advanced Functional Materials
6.3 Electronic Properties of Carborane-Containing Conjugated Polymers
6.4 Luminescent Materials
6.5 Photochemistry of o-Carboranes
6.6 Applications for Solid-State Luminescent Materials
6.7 Stimuli-Responsive Luminochromic Materials
6.8 Conclusion
7 LOW BANDGAP CONJUGATED POLYMERS
7.1 Introduction
7.2 Design Principles of LBG-CPs
7.3 Synthesis of LBG-CPs
7.4 Application of LBG-CPs
7.5 Conclusion and Perspective
8 POLYMERS WITH THREE-DIMENSIONAL CONJUGATED MOLECULES
8.1 Introduction
8.2 Corannulene Containing Polymer
8.3 Supramolecular Polymers Based on Bowl-Shaped Pi-Conjugated molecules
8.4 Helicene-Based Polymers
8.5 Conclusion and Outlook
9 CONJUGATED POLYMERS FOR ENERGY STORAGE DEVICES
9.1 Introduction
9.2 Conjugated Polymers as Binder Materials in LIBs
9.3 Conjugated Polymers as Anodic Materials
9.4 Polymerizable Conjugated Molecules as Electrolyte additives
9.5 Pi-Conjugated Polymers as Electrocatalysts
9.6 Conclusion
10 CONJUGATED POLYMERS AND THEIR APPLICATIONS IN ORGANIC FIELD EFFECT TRANSISTOR, ORGANIC ELECTROCHEMICAL TRANSISTORS, AND ORGANIC THERMOELECTRICS
10.1 Introduction
10.2 Polymers for Organic Field Effect Transistors
10.3 Organic Electrochemical Transistors (OECTs)
10.4 Organic Thermoelectrics (OTEs)
11 PI-CONJUGATED POLYMERS WITH CONTROLLED HIGHER-ORDER STRUCTURES: POLY(ACETYLENE)S AND POLY(ARYLENEETHYNYLENE)S
11.1 Introduction
11.2 Helical Substituted Poly(acetylene)s
11.3 Poly(aryleneethynylene)s
11.4 Platinum-Containing Poly(aryleneethynylene)s
11.5 Summary and Outlook
12 ADVANCES IN ORGANIC SOLAR CELL PERFORMANCE INVOLVING ANTHRACENE AND ANTHANTHRONE CORE POLYCYCLIC AROMATIC MATERIALS
12.1 Introduction
12.2 Anthracene-Containing Materials for OSCs Applications
12.3 Anthanthrone-Containing Materials for OSCs Applications
12.4 Hole Transporting Materials
12.5 Conclusions
13 CONJUGATED POLYMERS FOR BIOMEDICAL APPLICATIONS
13.1 Introduction
13.2 Biosensing and Biological Detection
13.3 Biological Imaging
13.4 Therapeutic Applications
13.5 Conclusions
Index
Chapter 1
Transition Metal-catalyzed Polycondensation
Takaki Kanbara1, and Junpei Kuwabara2
1Institute of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
2Tsukuba Research Center for Energy Materials Science (TREMS), Institute of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
1.1 Introduction
Transition metal-catalyzed homo- and cross-coupling reactions have emerged as versatile synthetic methodologies that are widely employed for the synthesis of a variety of organic compounds [1-9]. Cross-coupling reactions of various organometallic (Mg, Zn, Sn, B, and Si) reagents and aryl halides are suitable for bond formation at sp2 and sp carbons. Profs. Negishi, Suzuki, and Heck were awarded the Nobel Prize in Chemistry in 2010 for their pioneering work on Pd-catalyzed cross-coupling reactions in organic synthesis [10-13].
Scheme 1.1 shows the general mechanism of cross-coupling reactions. Ni- and Pd-based complexes are commonly employed as transition metal catalysts. In general, cross-coupling reactions involve three steps: an oxidative addition reaction across the carbon-halogen bond as an electrophile, transmetalation with the main group in the organometallic reagents acting as nucleophiles, and reductive elimination, resulting in the formation of the carbon-carbon bonds and regeneration of the active catalyst. Various organometallic reagents, including Grignard reagents (Kumada-Tamao-Corriu), zinc (Negishi), stannane (Migita-Kosugi-Stille), boron (Suzuki-Miyaura), silane (Hiyama), copper (Sonogashira), lithium, and mercury compounds, can be used [1-13].
Scheme 1.1 General mechanism of metal-catalyzed cross-coupling reaction. Ar1 and Ar2 denote aromatic units, M and M´ represent an organometallic moiety, and X represents halogen or pseudo-halogen.
In terms of polymer synthesis, various -conjugated polymers have been designed and developed by the transition metal-catalyzed homo- and cross-coupling polycondensation over the last few decades [14-17]. This chapter describes a fundamental overview of the transition metal-catalyzed homo- and cross-coupling polymerization reactions used in the synthesis of various -conjugated polymers. The utilization of transition metal-catalyzed bond functionalization and carbon-nitrogen bond formations in synthesizing -conjugated polymers is also involved.
1.2 Ni-catalyzed Polycondensation
The utilization of transition metal-catalyzed cross-coupling reactions to -conjugated polymers was first reported by Yamamoto et al. in the synthesis of poly(-phenylene), which was prepared by Ni-catalyzed Grignard coupling of 1,4-dibromobenzene [14, 18, 19]. One of the bonds reacts with Mg to form the Grignard reagent and undergoes further coupling reactions based on the Kumada-Tamao-Corriu cross-coupling reaction (Scheme 1.2a). Polythiophene (PTh) and poly(3-alkylthiophene)s (PRThs) were synthesized using the same protocol (Scheme 1.2b) [20].
Scheme 1.2 Ni-catalyzed Grignard coupling polycondensation of (a) 1,4-dibromobenzene and (b) 2,5-dibromo-3-alkylthiophene.
While the reactions are simple and provide several -conjugated polymers, the regioregularity cannot be controlled using the conventional protocol (Scheme 1.3). The synthesis of regioregular PRThs involving head-to-tail (HT) repeating units can be realized by the Ni-catalyzed polycondensation of regio-controlled organometallic monomers (Scheme 1.4). The reaction of 2,5-dibromo-3-alkylthiophene with metallic Mg or Zn was shown to give the organometallic species at the 5-position. Further addition of the Ni catalyst initiated polymerization to give PRThs with high HT regioregularity (HT-P3RTh, Schemes 1.4a, b) [21-23]. The active monomers for regioregular PRThs were also generated by deprotonation of 2-bromo-3-alkylthiophene with Knochel-Hauser base, 2,2,6,6-tetramethyl piperidinyl magnesium chloride lithium chloride complex (TMPMgCl·LiCl) (Scheme 1.4c) [23]. Regioregular PRThs have been of particular interest because regioregular polymers exhibit remarkable physical properties such as higher crystallinity and electrical conductivity in the solid state than regio-random PRThs [14, 24]. It should be noted that the polymerization reaction in Scheme 1.4 could proceed in a chain-growth manner, in which propagation occurs at the polymer end, despite the reaction being based on a polycondensation. Thus, the reaction allows the control of the molecular weight with a narrow molecular weight distribution and the formation of block copolymers by successive monomer additions [23, 25-30]. Chapter 2 will provide a detailed description of the chain-growth polycondensation.
Scheme 1.3 Synthesis of regioirregular PRTh.
Scheme 1.4 Synthesis of regioregular PRTh mediated by (a) Grignard reagent, (b) Rieke zinc, and (c) Knochel-Hauser base.
Dehalogenative homo-coupling polycondensation of dihaloaromatic monomers using zerovalent Ni complexes (Ni(0)Lm) such as Ni(PPh3)4 and Ni(cod)2 (cod = 1,5-cyclooctadiene), has also contributed to design various -conjugated polymers (Scheme 1.5a) [14, 18]. The protocol proceeds under mild conditions and enables the polycondensation of dihaloaromatic monomers, such as 2,5-dibromopyridine and 1,4-dichloroanthracene, which has not been achieved by other polycondensation methods. While the reaction generally requires a stoichiometric amount of Ni(0) complex, the Ni(0)Lm complexes formed in situ by chemical (e.g. by Zn, NaH, and hydrazine hydrate) or electrochemical reduction of Ni(II) compounds are available for polycondensation [31-35] thus facilitating the following catalytic reactions (Scheme 1.5b).
Scheme 1.5 Dehalogenative homo-coupling polycondensation using (a) a stoichiometric amount of Ni(0) complex and (b) Ni(0) complexes formed by chemical and electrochemical reduction.
1.3 Pd-catalyzed Polycondensation
Pd complexes are known as useful catalysts for various coupling reactions, particularly the Pd-catalyzed Migita-Kosugi-Stille, Suzuki-Miyaura, Sonogashira, and Mizoroki-Heck coupling reactions have been utilized for polycondensation giving various -conjugated polymers [14-17]. This is due to some inherent advantages such as increased diversity and tenability of the catalysts, oxidative and aqueous stability, and relatively facile isolation and structural analysis of the complexes, which aid their mechanistic and methodological developments. With the development of these cross-coupling reactions utilized polycondensation, -conjugated polymers consisting of alternating aromatic units have been prepared easily, and the variation of the -conjugated polymers has been dramatically increased.
The Migita-Kosugi-Stille coupling reaction is a Pd-catalyzed cross-coupling reaction between aryl halides and organostannic compounds and the Suzuki-Miyaura coupling reaction is a versatile bond formation reaction between aryl halides and organoboronic acids. One important difference between the cross-coupling reactions is that the Suzuki-Miyaura coupling reaction requires the activation of the organoboronic acid with a base. This activation facilitated transmetalation (Scheme 1.6). The major advantage of these cross-coupling reactions is that they can tolerate various functional groups and proceed under mild conditions. The Suzuki-Miyaura coupling reaction can even be conducted in aqueous media. The feature of the coupling reactions offers the opportunity to design a variety of -conjugated polymers with functional moieties manifesting many highly desirable properties (Scheme 1.7a, b) [14-17, 36, 37]. In addition, these cross-coupling polymerization protocols also proceed in a chain-growth polymerization manner from the initiator unit derived from the Pd catalyst [25-30]; the details are to be described in Chapter 2.
Scheme 1.6 Reaction mechanism of the Suzuki-Miyaura coupling reaction. Ar1 and Ar2 denote aromatic units and X denotes halogen or pseudo-halogen.
Scheme 1.7 Pd-catalyzed polycondensation via (a) Migita-Kosugi-Stille, (b) Suzuki-Miyaura, and (c) Sonogashira coupling reactions.
The Pd-catalyzed cross-coupling of aryl halides with terminal alkynes employing co-catalytic Cu(I) halides and an amine base is referred as the Sonogashira coupling reaction [9]. The polycondensation reactions between dihaloaromatic monomers and diethynyl aromatic monomers give poly(arylene ethynylene) type -conjugated polymers (Scheme 1.7c) [38]. In this reaction, the Cu(I) halides react with the terminal alkyne to produce a Cu(I) acetylide, which serves as an activated species for the coupling reaction. Transmetalation proceeded in the usual manner for the Pd complex (Scheme 1.1). A Cu-co-catalyzed mechanism for the Sonogashira coupling reaction was also proposed since the rate of the reaction was affected by the nature of the substituent and the halide of the copper(I) salt as well as the aryl halide [39].
The Mizoroki-Heck...
