Electron-rich Monomers Research Articles

Electron Transfer Drives the Photosensitized Polymerization of Contrast Agents by Flavoprotein Tags for Correlative Microscopy.

Singlet oxygen generation has long been considered the key feature that allows genetically encoded fluorescent tags to produce polymeric contrast agents for electron microscopy. Optimization of the singlet oxygen sensitization quantum yield has not included the effects of electron-rich monomers on the sensitizer's photocycle. We report that at monomer concentrations employed for staining, quenching by electron transfer is the primary deactivation pathway for photoexcitations. A simple photochemical model including contributions from both processes reproduces the observed reaction rates and indicates that most of the product is driven by pathways that involve electron transfer with monomers─not by the sensitization of singlet oxygen. Realizing the importance of these competing reaction pathways offers a new paradigm to guide the development of genetically encodable tags and suggests opportunities to expand the materials scope and growth conditions for polymeric contrast agents (e.g., biocompatible monomers, O2 poor environments).

Linking electron-rich Pillar[5]arene into hyper-cross-linked polymers for highly effective adsorption of iodine vapor

Four hyper-cross-linked polymers were synthesized by linking electron-rich monomers with an electron-rich cross-linker via the Friedel–Crafts reaction. Among these polymers, P4, which was constructed with decaalkyne pillar[5]arene and bibenzyl chloride, adsorbed iodine vapor with a capacity of 3.930 g g−1, outperforming most supramolecular macrocycle-based porous polymers. The pillar[5]arene macrocycle contributed various types of adsorption sites, including aromatic rings, diynes, and oxygen atoms. The abundance of effective adsorption sites and the high specific surface area (1615.5 m2 g−1) were responsible for the excellent adsorption capacity of P4. Because these polymers are easy to synthesize and regenerate and can be mass produced, they are promising candidates for large-scale applications.

Transforming an insulating metal–organic framework into electrically conducting metal–organic framework⊃conducting polymer composites

Owing to their diverse potentials to help advance modern electronics and energy technologies, electrically conducting metal–organic frameworks (MOFs) have emerged as one of the most coveted functional materials within the past decade. The key to developing electrically conducting MOFs is to equip them with mobile charge carriers and facilitate long-range charge movement. Circumventing the challenges and unpredictability associated with the construction of intrinsically conducting MOFs, herein, we have converted a structurally robust and porous but intrinsically insulating Zn-dpzNDI MOF based on an electron deficient dipyrazolate-naphthalenediimide (dpzNDI) ligand into electrically conducting MOF⊃conducting-polymer (MOF⊃CP) composites via oxidative polymerization of preloaded redox-active 3,4-ethylenedioxythiophene (EDOT) and pyrrole (Py) monomers to corresponding PEDOT and PPy polymers, which are well-known hole-transporters. After monomer loading and in-situ polymerization, the resulting MOF⊃CP composites remained crystalline but became less porous, suggesting that the amorphous CP chains were mostly confined to the MOF cavities. The presence of CPs was confirmed by infra-red (IR), diffuse-reflectance UV–Vis–NIR and STEM-EDX analyses. Whereas the pristine MOF had immeasurably low conductivity (σ < 10−12 S/m), the MOF⊃PEDOT and MOF⊃PPy composites displayed significantly higher electrical conductivity: 1.8 × 10−5 and 2.5 × 10−3 S/m, respectively. Thus, we have transformed an intrinsically insulating MOF into electrically conducting MOF⊃CP via in-situ oxidative polymerization of electron-rich monomers, a versatile strategy that could be adopted to engineer this much coveted but elusive electronic property practically in any porous MOFs.

Biobased Polymers via Radical Homopolymerization and Copolymerization of a Series of Terpenoid-Derived Conjugated Dienes with exo-Methylene and 6-Membered Ring.

A series of exo-methylene 6-membered ring conjugated dienes, which are directly or indirectly obtained from terpenoids, such as β-phellandrene, carvone, piperitone, and verbenone, were radically polymerized. Although their radical homopolymerizations were very slow, radical copolymerizations proceeded well with various common vinyl monomers, such as methyl acrylate (MA), acrylonitrile (AN), methyl methacrylate (MMA), and styrene (St), resulting in copolymers with comparable incorporation ratios of bio-based cyclic conjugated monomer units ranging from 40 to 60 mol% at a 1:1 feed ratio. The monomer reactivity ratios when using AN as a comonomer were close to 0, whereas those with St were approximately 0.5 to 1, indicating that these diene monomers can be considered electron-rich monomers. Reversible addition fragmentation chain-transfer (RAFT) copolymerizations with MA, AN, MMA, and St were all successful when using S-cumyl-S’-butyl trithiocarbonate (CBTC) as the RAFT agent resulting in copolymers with controlled molecular weights. The copolymers obtained with AN, MMA, or St showed glass transition temperatures (Tg) similar to those of common vinyl polymers (Tg ~ 100 °C), indicating that biobased cyclic structures were successfully incorporated into commodity polymers without losing good thermal properties.

ProTOT: Synthesis of the missing member of the 3,4-chalcogen substituted bridged thiophenes and its utilization in donor-acceptor polymers

Synthesis of sulfur containing derivatives of bridged dioxythiophene based polymers (PEDOT and PProDOT) and their applications in electrochromism have been pursued in recent years with promising results. Interestingly, synthesis of 3,4-dihydro-2H-thieno[3,4-b][1,4]oxathiepine (ProTOT) has not been pursued.. Here, we describe the synthesis of this novel electron rich monomer and D-A-D type monomer that contain ProTOT as the donor and benzo[c][1,2,5]thiadiazole as the acceptor. ProTOT cannot be electrochemically polymerized to yield the corresponding polymer PProTOT. However, the D-A-D monomer utilizing ProTOT as the donor unit was electropolymerized successfully to yield P(ProTThia) and its electrochromic properties and performance in amperometric biosensors have been investigated. P(ProTThia) was shown to be both p and n-dopable with 4 distinctly different colors at different redox states. P(ProTThia) showed a promising optical contrast of 35% in the visible region and excellent optical contrast of 80% in the NIR region. A novel amperometric biosensor for the detection of glucose consisting of P(ProTThia), chitosan (CHIT) and multi-walled carbon nanotubes (MWCNT) was also constructed. Herein, for the first time, we propose that a specific combination of this trio can be used as an inexpensive alternative and effective way to fabricate highly sensitive and fast response glucose biosensors. The proposed glucose sensing system possessed superior properties with KMapp value of 0.05 mM, 32 μM limit of detection and 63.76 μA mM−1 cm−2 sensitivity which was also tested with a commercial beverage sample to ratify the feasibility of the proposed sensor.

Supramolecular copolymerization driven by integrative self-sorting of hydrogen-bonded rosettes

Molecular recognition to preorganize noncovalently polymerizable supramolecular complexes is a characteristic process of natural supramolecular polymers, and such recognition processes allow for dynamic self-alteration, yielding complex polymer systems with extraordinarily high efficiency in their targeted function. We herein show an example of such molecular recognition-controlled kinetic assembly/disassembly processes within artificial supramolecular polymer systems using six-membered hydrogen-bonded supramolecular complexes (rosettes). Electron-rich and poor monomers are prepared that kinetically coassemble through a temperature-controlled protocol into amorphous coaggregates comprising a diverse mixture of rosettes. Over days, the electrostatic interaction between two monomers induces an integrative self-sorting of rosettes. While the electron-rich monomer inherently forms toroidal homopolymers, the additional electrostatic interaction that can also guide rosette association allows helicoidal growth of supramolecular copolymers that are comprised of an alternating array of two monomers. Upon heating, the helicoidal copolymers undergo a catastrophic transition into amorphous coaggregates via entropy-driven randomization of the monomers in the rosette.

Synthesis and electrochromic properties of cross-linked and soluble conjugated polymers based on 5, 8, 14, 17-tetrabromoquinoxaline[2′, 3':9,10]phenanthro[4,5-abc]phenazine as the multifunctionalized acceptor unit

Three novel electrochromic copolymers PTPE-1, PTPE-2, and PTPE-3 were synthesized by changing the ratio of donor to acceptor using the Stille coupling polymerization. 5,8,14,17-tetrabromoquinoxaline[2′,3':9,10]phenanthro[4,5-abc] phenazine (monomer b) was first introduced and employed as multi-functionalized unit with bisquinoxaline structure and high planarity, which was used as the acceptor unit. Two electron-rich monomers ProDOT-decyl2 (monomer a) and thiophene (monomer c) are selected as the co-monomers and donor units. The three polymers were tested by X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), spectro-electrochemistry, kinetics, thermogravimetric analysis (TG), etc. All three polymers have narrow band gaps of lower than 1.85 eV and satisfactory thermal stability. As to electrochromic switching properties, the polymers showed high optical contrast and fast response time both in the visible and near-infrared regions. The optical contrasts are 53.35% at 540 nm and 66.49% at 1325 nm for PTPE-3, and its coloration efficiencies are 163 cm2 C−1 at 540 nm, 205 cm2 C−1 at 1325 nm, with fast switch time of less than 1 s. The color changes of three polymers were diversified and distinct, PTPE-1 changes from chestnut color to blue-gray color, PTPE-2 changes from dull red color to wathet color and PTPE-3 changes from deep red color to light blue-gray color. The excellent properties of the polymers might result from their cross-linked structure and consequent formation of the compatible ion transport channel.

The History of Palladium-Catalyzed Cross-Couplings Should Inspire the Future of Catalyst-Transfer Polymerization.

Conjugated polymers are the workhorse materials in organic electronics, a field that is rapidly growing to encompass energy storage devices such as supercapacitors and batteries. The highest-performing materials today have incredibly diverse structures and are accessed via step-growth polymerizations. This method results in limited control over the polymer's molecular weight, sequence, and dispersity, all of which can significantly impact device performance. The discovery of catalyst-transfer polymerization (CTP) in 2004 was predicted to change this landscape. Instead, nearly 14 years later, the CTP scope remains mostly limited to polymerizing small, electron-rich monomers. There is a pronounced gap between the rich array of structures utilized in organic electronics and what can be polymerized in a living, chain-growth fashion via CTP. Here, we suggest that palladium precatalysts could bridge this gap based on their huge versatility in the small-molecule cross-coupling literature. We highlight specific ancillary ligands from the small-molecule literature that we anticipate are candidates for enabling diverse conjugated polymer syntheses based on nearly a decade of research into the CTP mechanism. In addition, we describe several recent promising examples of CTP mediated by Pd precatalysts that serve as inspiration for the future. We present this Perspective as a call-to-action to advance organic electronics with CTP.

Difluorination at Boron Leads to the First Electrophilic Ligated Boryl Radical (NHC-BF2. ).

1,3-Dimethylimidazol-2-ylidene difluoroborane (NHC-BF2 H) was prepared in a one-pot, two-step reaction from the parent ligated borane (NHC-BH3 ). The derived difluoroboryl radical (NHC-BF2. ) was generated by laser flash photolysis experiments and characterized by UV spectroscopy and rate-constant measurements. It is transient and reacts quickly with O2 . Unusually, it also reacts more rapidly with ethyl vinyl ether than with methyl acrylate. By this measure, it is the first electrophilic ligated boryl radical. Both NHC-BH3 and NHC-BF2 H serve as co-initiators in bulk photopolymerizations, converting both electron-poor and electron-rich monomers at roughly similar rates. However, the difluorinated coinitiator provides polymers with dramatically increased chain lengths from both monomers.

Nonstoichiometric Stille Coupling Polycondensation Via Intramolecular Pd(0) Catalyst Transfer Using Excess Imide-Based Dibromo Monomers

π-Conjugated polymers are widely used for the organic electronic devices, such as Organic Light Emitting Diodes (OLED), Organic Photovoltaics (OPV) and Organic Thin-film Transistors (OTFT). These polymers are typically synthesized by AA+BB type polycondensations based on a transition-metal-catalyzed cross-coupling reaction. Generally, the number-average degree of polymerization of polymers (X n) synthesized by AA+BB-type polycondensations is generally determined by Carothers equation as X n=(1+r)/(1+r-2rp), where r is the stoichiometric molar ratio between AA and BB monomers and p is the extent of the reaction. Thus, the molecular weight of the polymers relies significantly on the stoichiometry of the monomers. In our previous report, high-molecular-weight n-type polymers were exceptionally obtained from 2,5-bis(trimethylstannyl)thiophene (1) and 1~10 fold excesses of 4,9-dibromo-2,7-bis(2-decyltetradecyl)benzo[lmn][3,8]-phenanthroline-1,3,6,8-tetraone by the Stille coupling polycondensation. The reason for the successful nonstoichiometric Stille coupling polycondensation can be explained by the intramolecular Pd(0) catalyst transfer after the substitution reaction of a bromo moiety of the dibromo-monomer with one distannyl-monomer, resulting in the C-Pd(II)-Br terminal via Pd(0)-π association, which can be readily substituted with other distannyl-monomers to afford all-stannylated oligomeric/polymeric terminals. Therefore, the excess dibromo monomers are not consumed for capping the oligomeric/polymeric during polymerization. In addition, it was suggested that the intramolecular Pd(0) catalyst transfer was promoted by the electron-deficient NDI structure in the model reactions. On the other hand, Yokozawa group also reported nonstoichiometric Suzuki-Miyaura coupling polycondensation via intramolecular Pd(0) catalyst transfer almost at the same time. In this report, they concluded that the electron-rich monomers are suitable for the intramolecular Pd(0) catalyst transfer because of the strong Pd(0)-π interaction between Pd(0) and dibromo monomers. Therefore, determining the criteria for the Pd(0) catalyst-transfer systems using electron-deficient monomers is necessary to extend the applicable monomers for stoichiometry-independent polycondensations. Here, we report the effect of monomer structures and ligand types suitable for the nonstoichiometric Stille coupling polycondensation. First, the model reactions were examined between 2-tributylstannylthiophene (2) and 1 molar equiv. 1,3-dibromo-5-octylthieno[3,4-c]pyrrole-4,6-dione (3), or N-octyl-3,6-dibromophthalimide (4) which have the imide-substituent and the compact thiophene/phenylene skeletons. The results implied that the intramolecular Pd(0) catalyst transfer occurred using 3 with tri(o-tolyl)phosphine (P(o-tolyl)3) as the ligand; however, no catalyst transfer occurred using 4 with P(o-tolyl)3, judged from the presence/absence of the monoadduct product. On the other hand, the employment of a more electron-rich ligand, tri(t-butyl)phosphine (P(t-Bu)3), led to the intramolecular Pd(0) catalyst transfer on 4. It was suggested that the strong electron-donating ligand promoted the intramolecular Pd(0) catalyst transfer. Based on the model reactions, we examined the polymerization between 1 and 1,3-dibromo-5-(2-hexyldecyl)thieno[3,4-c]pyrrole-4,6-dione (5) or N-(2-hexyldecyl)-3,6-dibromophthalimide (6) under the nonstoichiometric conditions. Unfortunately, only oligomers were obtained in stoichiometric and nonstoichiometric condition between 1 and 5. In contrast, the high-molecular-weight polymers could be synthesized using 6 with P(t-Bu)3 under the nonstoichiometric conditions ([6]0/[1]0 =2~10). All polymers were confirmed to have almost the same structure by 1H NMR spectroscopy. The model reaction was further investigated using another electron-deficient benzothiadiazole (BTz)-based monomer instead of 4. However, the catalyst transfer does not appear to happen on the BTz monomer with any of the tested Pd catalysts including Pd2(dba)3/P(o-tolyl)3, Pd/P(t-Bu)3 and PEPPSI- i Pr based on the fact that mono-substituted products were obtained from the reaction between 2 and an equimolar amount of 4,7-dibromo-2,1,3-benzothiadiazole under all conditions. This result indicate that the specific feature of the imide substituents is necessary for the successful nonstoichiometric Stille coupling polycondensation. In conclusion, the high-molecular-weight polymers could be obtained under the nonstoichiometric conditions between 1 and 6 ([6]0/[1]0 =2~10) via the intramolecular Pd(0) catalyst transfer. The strong-electron donating phosphine ligand and the imide-substituent is crucial for the success of the intramolecular Pd(0) catalyst transfer in nonstoichiometric Stille coupling polycondensation. Figure 1

A supramolecular bottlebrush polymer assembled on the basis of cucurbit[8]uril-encapsulation-enhanced donor–acceptor interaction

A supramolecular bottlebrush polymer has been constructed in water through the self-assembly of a rigid electron-deficient building block and an electron-rich monomer which bears two tetraethylene glycol chains, driven by CB[8]-encapsulation-enhanced donor–acceptor interaction. The as-formed supramolecular bottlebrush polymer has been characterized by 1H NMR titration experiment, UV–vis spectroscopy, DLS and 2D 1H NMR DOSY.

Theoretical study of thieno-thiophene based low band gap copolymers and substituent effect on the optoelectronic properties of them

This paper studies donor-acceptor systems which incorporate benzodithiophene (BDT), benzodifuran (BDF) and benzodipyrrole (BDP) units as the electron-rich monomer with TT unit representing the electron-deficient monomer. This research is based on employing density functional theory (DFT) and time-dependent DFT (TD-DFT). The highest occupied molecular orbitals (HOMO) and the lowest unoccupied molecular orbitals (LUMO), HOMO-LUMO gaps and dihedral-angles of these copolymers were calculated using oligomer extrapolation technique and periodic boundary condition (PBC) method. The optical band gaps and UV–vis absorption spectra of aforementioned copolymers were obtained by TD-DFT at the same level of theory. Based on the fair agreement between PBC-DFT calculated results and experimental data, the substituent effects of Cl, Br, CCH, COH, NO2, OH, SH and NH2 groups were investigated by PBC-DFT method. The difference between the ground and excited-states dipole moment (Δμge) of all derivatives were also calculated. Taking these results into account, a better understanding of the substituent effects on the photo-physical properties of the copolymers under study was achieved. Due to the shift of HOMO and LUMO energy levels, smaller band gaps and higher Δμge are observed in some derivatives. The calculation results demonstrate that the substitution of COH and NO2 by fluorine in BDF-TT and BDP-TT leads to higher maximum theoretical efficiencies (η).

Toward Practical Useful Polymers for Highly Efficient Solar Cells via a Random Copolymer Approach.

Using benzo[1,2-b:4,5-b']dithiophene and two matched 5,6-difluorobenzo[2,1,3]thiadiazole-based monomers, we demonstrate that random copolymerization of two electron deficient monomers, alternating with one electron rich monomer, forms a successful approach to synthesize state-of-the-art semiconducting copolymers for organic solar cells. Over a range of compositions, these random copolymers provide impressive power conversion efficiencies (PCEs) of about 8.0%, higher than those of their binary parent polymers, and with little batch-to-batch variation. A PCE over 8% could also be achieved when the active layer was deposited from nonhalogenated solvents at room temperature.

Synthesis and electrochemical investigation of beta-substituted thiophene-based donor–acceptor copolymers with 3,4-ethylenedioxythiophene (EDOT)

The present work reports the synthesis of four electron-acceptor beta-substituted thiophenes that were studied as monomers for electrochemical polymerization with 3,4-ethylenedioxythiophene (EDOT), an electron-donating monomer, aiming the combination of electron-acceptor and donor monomer thiophene to a simpler and convenient build up of novel donor–acceptor copolymeric materials via electrochemical polymerization. Four novel copolymers poly(EDOT-co-3-thiophene phenylacetate), (PEDOT-co-PPhTAc-2a), poly(EDOT-co-3-thiophene(4-nitrophenyl)acetate) (PEDOT-co-PPhTAc-2b), poly(EDOT-co-3-thiophenephenylcarboxylate) (PEDOT-co-PPhTCb), and poly(EDOT-co-3-(phenoxymethyl)thiophene) (PEDOT-co-PPhOMT) were electrochemically polymerized. The monomers were characterized by spectrometric techniques (FTIR, 1H NMR, and 13C NMR), and the copolymers were identified by electrochemical analyses and FT-IR. Although the corresponding homopolymers could not be obtained, in the presence of EDOT, the copolymers were formed in a quasi-reversible electrochemical kinetics. The infrared spectra of the copolymers as well the electrochemical profile corroborates their obtaining. The mass variation during the electrosynthesis was analyzed using a quartz crystal microbalance. The film’s morphologies were investigated by SEM. Interestingly, the combination of electron-rich monomer thiophene (EDOT) and these electron-deficient carboxy-substituted thiophenes might be a convenient building block couple to increase the performance control of physic-chemical properties of mixed polythiophenes with innovative applications and they also showed a possible applicability as charge storage device.

Conjugated Polymers with Switchable Carrier Polarity

Stimuli responsive polymers can change their properties as a result of their environment. Factors such as temperature, light, pH, or solvent can all trigger a polymer response. We present conjugated polymers with switchable carrier polarity, accomplished using a functional group that can be converted from electron donating to electron withdrawing. The polymers presented herein are polyselenophenes containing α-ketal side-chains. The α-ketal side-chains can be converted to electron withdrawing α-ketone side-chains postpolymerization. Since the starting monomer is relatively electron-rich, it can be polymerized using chain growth methods. Switching the electron donating ability of the side chain postpolymerization is an effective way to synthesize electron-deficient conjugated polymers from electron-rich monomers. Whereas the α-ketal polymer has optoelectronic properties that are consistent with other electron-rich (p-type) polymers, the α-keto polymer features a broad red optical-absorption, narrow HOMO–LU...

Symmetry breaking polymerization: one-pot synthesis of plasmonic hybrid Janus nanoparticles.

Asymmetric hybrid nanoparticles have many important applications in catalysis, nanomotion, sensing, and diagnosis, however ways to generate the asymmetric hybrid nanoparticles are quite limited and inefficient. Most current methods rely on interfacial adhesion and modification of already formed particles. In this article we report a one-pot, facile and scalable synthesis of anisotropic Au-polymer hybrid nanoparticles via interfacial oxidative dispersion polymerization. The interfacial nucleation and polymerization lead to spontaneous symmetry breaking and formation of the Janus particles. The reaction is initiated by monomer radicals generated by the strong oxidant HAuCl4, which is itself later reduced by the electron-rich monomers to self-nucleate and form Au nanoparticles (NPs). The competition between divinylbenzene adsorption and the PVP capping agent results in effective partial surface wetting, forming asymmetric Au-PDVB hybrid nanoparticles, by confining growth of each material to its own phase. Such spontaneous symmetry breaking, important in morphogenesis, with control over the subsequent growth processes should lead to significant advances in the synthesis of asymmetric nanostructures.

Cationic RAFT polymerization using ppm concentrations of organic acid.

A metal-free, cationic, reversible addition-fragmentation chain-transfer (RAFT) polymerization was proposed and realized. A series of thiocarbonylthio compounds were used in the presence of a small amount of triflic acid for isobutyl vinyl ether to give polymers with controlled molecular weight of up to 1×10(5) and narrow molecular-weight distributions (Mw /Mn <1.1). This "living" or controlled cationic polymerization is applicable to various electron-rich monomers including vinyl ethers, p-methoxystyrene, and even p-hydroxystyrene that possesses an unprotected phenol group. A transformation from cationic to radical RAFT polymerization enables the synthesis of block copolymers between cationically and radically polymerizable monomers, such as vinyl ether and vinyl acetate or methyl acrylate.

Oxidative chemical vapor deposition of polyacenaphthylene, polyacenaphthene, and polyindane via benzoyl peroxide

A method is presented to polymerize inexpensive and readily available electron-rich monomers via oxidative chemical vapor deposition. The process uses benzoyl peroxide, an organic oxidant, flash evaporated from a chloroform solution via direct liquid injection. The deposition temperatures ranged from 35°C for indane to 125°C for acenaphthylene and acenaphthene. These temperatures were determined by the volatility and melting point of the monomers, which were vaporized without the addition of a carrier gas. Benzoyl peroxide was not cracked into its respective free radical species but instead used as an oxidant at the substrate temperature. Polyacenaphthylene was deposited as a yellow film indicative of its highly conjugated polymer backbone, whereas polyacenaphthene and polyindane were both transparent dielectrics. Polyacenaphthylene and polyacenaphthene had higher average indices of refraction 1.6819 and 1.6640 (at 632.8nm) than polyindane 1.5690, likely representing their higher density.

Synthesis and photovoltaic properties of donor–acceptor polymers incorporating a structurally-novel pyrrole-based imide-functionalized electron acceptor moiety

A structurally-novel pyrrole-based imide-functionalized electron accepting monomer unit, 4,6-dibromo-2,5-dioctylpyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (DPPD), was prepared. The new DPPD unit was copolymerized with pyrrole-based electron rich monomers, such as thiophene-(N-alkyl)pyrrole-thiophene (TPT) and fused thiophene-(N-alkyl)pyrrole-thiophene (DTP) derivatives, to afford two new polymers, namely P(TPT-DPPD) and P(DTP-DPPD), respectively. The two polymers showed a strong absorption band at 300–600 nm and 300–650 nm, respectively, and their calculated optical band gaps were 2.09 eV and 1.89 eV, respectively. The electrochemical analysis reveals that the highest occupied molecular orbital (HOMO) energy levels of P(TPT-DPPD) and P(DTP-DPPD) were positioned at −5.55 eV and −5.24 eV, respectively, whereas their lowest unoccupied molecular orbital (LUMO) energy levels were positioned at −3.46 eV and −3.35 eV, respectively. The preliminary photovoltaic properties of the polymers, P(TPT-DPPD) and P(DTP-DPPD), were examined by fabricating polymer solar cells (PSCs) with each polymer as an electron donor and PC71BM as an electron acceptor. The PSCs fabricated with the configuration of ITO/PEDOT:PSS/P(TPT-DPPD) or P(DTP-DPPD):PC71BM/LiF/Al showed maximum power conversion efficiency (PCE) of 0.73% and 1.64%, respectively.

Conjugated Polymer Synthesis via Catalyst-Transfer Polycondensation (CTP): Mechanism, Scope, and Applications

The recent discovery of a living, controlled chain-growth method for synthesizing π-conjugated polymers has ignited the field and led to the development of many new materials. This Perspective focuses on the mechanistic underpinnings of the synthetic transformation, highlighting the controversial hypotheses and supporting data. A critical analysis of the literature revealed that the monomer scope remains largely limited to electron-rich monomers at this time. Last, a brief overview of some exciting new materials accessed via this method is provided.