No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Direct arylation polymerization towards a narrow bandgap conjugated microporous polymer with hierarchical porosity
Abstract
Conjugated microporous polymers are synthesized through facile one-step direct arylation polymerization of a single monomer unit, 8,11-dibromodithieno[3,2-a:2′,3′-c]phenazine, without preactivation of C-H bonds using organometallic reagents. The resulting polymers exhibit hierarchical porous structures and a narrow bandgap of 1.5 eV.
The 3,4‐ethylenedioxy thiophene (EDOT)‐based conjugated microporous polymers (CMPs) were readily constructed via facile one‐step direct arylation polymerication of CH from simple EDOT as a linker and commercially available aryl bromides of different geometries as the knots, without preactivation of CH bonds of aromatic building blocks using organometallic reagents. In contrast to conventional coupling reactions, this synthesis strategy not only has atomic efficiency but also can use simple thiophene derivatives as building blocks for synthesizing thiophene‐based CMPs of different structures, which avoids the synthesis of complex thiophene derivatives and are important for applications, for example, fluorescent sensors. The resulting EDOT‐based CMPs were used to fluorescent sensing to 2,4‐dinitrophenol (DNP), I 2 , and p‐nitrophenol (p‐NP), with high optimal Stern‐Volmer quenching constants.
Conjugated microporous polymers (CMPs) have been considered a type of promising visible-light-driven, organic photocatalysts. However, apart from designing high-performance CMPs from a molecular perspective, little attention is paid to improving the photocatalytic properties of these polymers through macrostructural regulation. Herein, we prepared a kind of hollow spherical CMPs involving carbazole monomers and studied their performance on the selective photocatalytic oxidation of benzyl alcohol under visible light irradiation. The results demonstrate that the introduction of a hollow spherical structure improves the physicochemical properties of the as-designed CMPs, including the specific surface areas, optoelectronic characteristics, as well as photocatalytic performance, etc. In particular, the hollow CMPs can more effectively oxidize benzyl alcohol compared to pristine ones under blue light illumination, and produce >1 mmol of benzaldehyde in 4.5 h with a yield of up to 9 mmol·g-1·h-1, which is almost 5 times higher than that of the pristine ones. Furthermore, such hollow architecture has a similar enhanced effect on the oxidation of some other aromatic alcohols. This work shows that the deliberate construction of specific macrostructures can better arouse the photocatalytic activity of the as-designed CMPs, which will contribute to the further use of these organic polymer semiconductors in photocatalysis areas.
In this paper, we report the synthetic strategy of direct arylation polymerization (DAP) for four 2,2'-bithiophene-based conjugated microporous polymers (the 2,2'-BTh-based CMPs) by coupling 2,2'-bithiophene with the building blocks containing bromine. Compared to conventional coupling polymerization, this synthetic scheme is simple, facile and atomically efficient owing to neither preactivating the C-H bonds in 2,2'-bithiophene using organometallic reagents nor synthesis of complex thiophene-based building blocks. The resulting 2,2'-BTh-based CMPs exhibit excellent thermal stability, high specific surface areas, and good microporosity. Their specific surface areas are higher than that of other previously reported CMPs prepared with DAP. The four 2,2'-BTh-based CMPs can be utilized for multicolor fluorescence sensing of 2,4-dinitrophenol (DNP) with the high sensitivity and selectivity. The sensitivities appear to increase with the degree of structural distortion.
Incorporating functional groups along conjugated microporous polymer conjugated backbones (CMPs) is an effective strategy to tune optoelectronic properties and achieve superior application performance. However, due to the incompatibility of the functional groups with the polymerization reaction, introducing these functionalities into the polymeric framework is often highly challenging. Herein, we report a facile route to synthesize aldehyde-functional group flanked (and aldehyde-free) CMPs TCMP-A (and TCMP) through a Pd-catalyzed direct arylation polymerization of 1,1,2,2-tetrakis(4-bromophenyl)ethene with 2,5-di(thiophene-2-yl)terephthalaldehyde or 1,4-di(thiophen-2-yl)benzene in good yields. The methodology circumvents the preactivation of building blocks and tolerates the presence of aldehyde-functional groups during polymerization, significantly reducing the number of synthetic steps. In contrast, synthesizing these polymers via conventional coupling methods, such as Suzuki, Stille, and Sonogashira reactions, is laborious. TCMP and TCMP-A exhibit strong visible light absorption (red edge of λabs = ~605 nm) and solid-state fluorescence (λem = 620 nm; ϕf = ~5%). The pendant aldehyde-functional group in TCMP-A enables selective fluorescent chemosensing of aliphatic and aromatic amines by enhancing the fluorescence of aliphatic amines and performing fluorescence quenching for aromatic amines. We develop aldehyde-functionalized conjugated microporous polymer (CMPs) via Pd-catalyzed direct arylation polymerization strategy. The method avoids the pre-fucntionalization and reduces the number of synthetic steps. The polymers exhibit strong visible light absorption (red edge of λabs = ∼605 nm) and solid-state fluorescence (λem = 620 nm; ϕf = ∼5%). The pendant aldehyde functional group in the polymer enables selective fluorescent chemosensing of aliphatic and aromatic amines by enhancing the fluorescence of aliphatic amines and performing fluorescence quenching for aromatic amines.
A new series of TPATTh-based CMPs have been synthesized via a readily synthetic scheme of C–H direct arylation polymerization (DAP) that involves thiophene-flanked arenes, tris[4-(2-thienyl)phenyl]amine (TPATTh) and commercially available multi-brominated aryls, (2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (TBrSBF), 1,3,6,8-tetrabromopyrene (TBrPy), 2,5-dibromopyrazine (DBrPy), and 1,6-dibromopyrene(DBrPz)). Preactivation of the C–H bonds in the aromatic monomers is not required. The resulting TPATTh-based CMPs display good thermal stability. The porosities of the TPATTh-based CMPs are lain on the structures of the multi-brominated aryls. The TPATTh-based CMPs present good fluorescence emission performances either in the solid states or dispersed in the solvents, and show different colors under 365 nm fluorescence irradiation. The resulting TPATTh-based CMPs were used to fluorescence sense to I2, PA, DNP, and o-NP with high Stern-Volmer quenching constants (Ksv).
In recent times, triazine-based Covalent Organic Polymers (COPs) have emerged as a central subclass of highly porous, N-rich organic materials, which are reported as highly efficient materials in a wide range of applications. Triazine-based COPs are formed using triazine or nitrile comprising organic precursors, which are connected through strong covalent linkages. Besides, the search for active, selective, and stable catalytic systems for numerous transformations is a pioneering field of interest for researchers worldwide. In the light of growing demand, it is highly desirable to present a well-organized and systematic inclusive review summing up triazine-based COP-derived catalyst systems in photocatalytic, organocatalytic, and MNP immobilized catalysis. Herein, we have summarised the current significant advances made in triazine-based COP synthetic strategies and their contemporary catalytic advancements. Synthetic methodologies are discussed in a simplistic way to create a better understanding for future researchers to modify these methods.
A novel strong electron-acceptor unit, 9,10-difluorodithieno[3,2-a:2',3'-c]phenazine (DTPz), is synthesized and applied in the design of two donor-acceptor type emitters displaying long-lived delayed emission. Using either 9,9-dimethyl-9,10-dihydroacridine (DMAC) or triisopropyl-substituted benzo[1,2-b:4,5-b']dithiophene (BDT-TIPS) as the donor component, push-pull type chromophores exhibiting charge-transfer emission are obtained and found to afford either thermally activated delayed fluorescence (TADF) for DMAC or room temperature phosphorescence (RTP) for BDT-TIPS.
Thiophene-flanked -conjugated building blocks are often used in the design of linear conjugated polymers as it leverages the reactivity of thiophene in numerous C-C coupling reactions to include a variety of donor and acceptor molecules in the conjugated backbone. However, this design strategy has been rarely used for synthesis of conjugated porous polymers (CPPs) until recently. In this article, we report facile synthesis and characterization of a library of CPPs synthesized via a versatile synthetic scheme of C-H direct arylation polymerization that involves commercially available aryl bromides and thiophene-flanked arenes. This synthetic scheme not only is atomically efficient compared to conventional couplings such as Suzuki, Stille and Sonogashira coupling, but also enables fine control of the optoelectronic properties and porosities that are important for applications such as photocatalysis.
Gel electrolytes were synthesized by the formation of microporous organic polymers in the presence of 0.077 ~ 0.77 M LiClO4 and N-methylpyrrolidone. Electrochromic devices fabricated using the gel electrolytes showed...
Wide‐bandgap π‐conjugated donor‐acceptor (D‐A) alternating copolymers consisting of benzo[1,2‐c:4,5‐c']dithiophene‐4,8‐dione (BDTD) as the electron‐accepting building block have demonstrated outstanding performances in organic bulk heterojunction (BHJ) solar cell devices. But the synthesis of these polymers has been largely limited to conventional polymerization techniques, particularly Stille‐coupling based polycondensations, which often involve tedious preactivation of C‐H bonds using highly flammable reagents such as butyl lithium and highly toxic reagents such as trialkyl tin chlorides. Herein, we report a “greener” synthetic route of direct arylation polymerization to a series of wide bandgap D‐A copolymers with a common acceptor building block of BDTD. The structure–property relationship in these polymers is characterized. We also present the device performances of these polymers in both thin‐film field‐effect transistors and organic BHJ solar cells involving the BDTD‐based polymers as the electron donors and fullerene derivatives as the electron acceptors. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 Three donor‐acceptor polymers containing benzo[1,2‐c:4,5‐c']dithiophene‐4,8‐dione (BDTD) are synthesized by direct arylation polymerization and their structure and optical properties are studied. Polymer containing quarterthiophene as the donor (P3) shows aggregation in solution state and BJH organic solar cells fabricated using P3 and PC71BM show power conversion efficiencies up to 3.5%.
Light‐driven water splitting is a potential source of abundant, clean energy, yet efficient charge‐separation and size and position of the bandgap in heterogeneous photocatalysts are challenging to predict and design. Synthetic attempts to tune the bandgap of polymer photocatalysts classically rely on variations of the sizes of their π‐conjugated domains. However, only donor‐acceptor dyads hold the key to prevent undesired electron‐hole recombination within the catalyst via efficient charge separation. Building on our previous success in incorporating electron‐donating, sulphur‐containing linkers and electron‐withdrawing, triazine (C3N3) units into porous polymers, we report the synthesis of six visible‐light active, triazine‐based polymers with a high heteroatom‐content of S and N that photocatalytically generate H2 from water: up to 915 µmol h‐1 g‐1 with Pt co‐catalyst, and ‐ as one of the highest to‐date reported values ‐ 200 µmol h‐1 g‐1 without. The highly modular Sonogashira‐Hagihara cross‐coupling reaction we employ, enables a systematic study of mixed (S, N, C) and (N, C)‐only polymer systems. Our results highlight that photocatalytic water‐splitting does not only require an ideal optical bandgap of ~2.2 eV, but that the choice of donor‐acceptor motifs profoundly impacts charge‐transfer and catalytic activity.
The rapid increase in the breadth and scope of transformations that involve metal-promoted activation of C–H bonds is fundamentally changing the field of synthetic chemistry. Direct arylation polymerization is a newly established synthetic protocol for atom economical, effective, and affordable preparation of conjugated polymers, which continue to be incredibly advantageous as operative materials for a diverse and continually evolving array of applications. This route toward conjugated polymers for high performance materials is particularly appealing because it circumvents the preparation of organometallic derivatives and the associated cryogenic air- and water-free reactions. Although a broad range of monomers are now readily polymerizable, direct arylation polymerization is known to produce defects in the chemical structure, which have a strong impact on the optical, electronic, and thermal properties of conjugated polymers. Fundamental understanding of the underlying considerations when employing different reaction protocols is required to truly enable a broad reaching platform.
Direct arylation polymerization enables “greener” synthesis of a high-performance semicrystalline π-conjugated polymer, poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophene-2-yl)benzo[c][1,2,5]thiadiazole) (PPDT2FBT). The resulting polymers show a hole mobility of 4.7 × 10⁻³ cm² V⁻¹ s⁻¹ in bottom-gate/top-contact field effect transistors, and a power conversion efficiency over 7% in organic bulk-heterojunction solar cells.
Triazine-containing conjugated porous polymers (CPPs) as a type of nitrogen-rich optoelectronic material have been promising for versatile applications such as gas separation, energy storage and catalysis. However, previous synthetic approaches such as ionothermal and solvothermal cyclotrimerization of aryl nitriles to these CPPs are limited to monomers that are stable against high temperatures (≥ 400 oC) or strong acids. As a consequence, a more generally applicable synthetic strategy under milder reaction conditions is highly demanded. In this article, we report direct arylation polymerization (DAP) towards such a synthetic strategy for a new series of robust triazine-core polymers by coupling 2,4,6-(tri-2-thienyl)-1,3,5-triazine (TTT) with multi-brominated monomers of varying geometries, without need of pre-activating the C-H bonds in the arene monomers. Direct C-H activation of TTT enables the facile incorporation of the triazine unit into multidimensional polymeric structures while the choice of comonomers gives good synthetic control of the morphologies, porosities and the optoelectronic properties of triazine-core CPPs. The resulting triazine-core polymers were used to catalyze the photooxidation of benzylamines and the polymers containing the highest fraction of triazine units gave > 99% conversion with a relatively low loading of the catalyst.
The synthetic control over pore structure remains highly desirable for porous organic frameworks. Here, we present a competitive chemistry strategy, i.e., a systematical regulation on Friedel–Crafts reaction and Scholl coupling reaction through tuning the ratios of monomers. This leads to a series of spirobifluorene-based microporous polymers (Sbf-TMPs) with systematically tuned porosities and N content. Unlike the existing copolymerization strategy by which the synthesized polymers exhibit a monotonic change tendency in the porosities, our networks demonstrate an unusually different trend where the porosity increases first and then decreases with the increasing Ph/Cl ratios for the monomers. This is mainly ascribed to the completion of coexisting reaction routines and the different “internal molecular free volumes” of the repeating units. The as-made networks feature tunable capacities for CO2 adsorption over a wide range and attractive CO2/N2 selectivities. Moreover, these donor–acceptor type frameworks exhibit selective and highly sensitive fluorescence-on or fluorescence-off properties toward volatile organic compounds, which implies their great potential in fluorescent sensors.
In this study, we report the synthesis of π-conjugated network polymers including unique fluorescent units via palladium-catalyzed direct (CH) arylation polycondensation of 1,2,4,5-tetrafluorobenzene with tetrabromoarenes. The obtained polymers, including tetraphenylethene (TPE) or pyrene (PYR) units, had microporous structures with the specific Brunauer–Emmett–Teller (BET) surface areas at 508 and 824 m² g⁻¹, respectively. These polymers possessed narrow pore distributions (<15 nm). These analyses supported that π-conjugated microporous polymers (CMPs) were synthesized by the direct arylation. Similar to the result of BET surface areas, carbon capture capacity of CMP based on PYR unit was higher than that of CMP based on TPE unit. Because the nitrogen capture capacity of these CMPs was low (≈ 0), selectivity of carbon dioxide adsorption was very high. TPE is a typical aggregation-induced emission unit but PYR is an aggregation-caused quenching (ACQ) molecule. The incorporation of TPE unit into the microporous polymer gave green-colored fluorescence (Φ = 0.12). The polymer including PYR units also showed the green-colored fluorescence (Φ = 0.05) even though the ACQ property. These synthesized CMPs exhibited characteristic solvatofluorochromism. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017
Three microporous polythiophenes P-TTT, P-THIDT and P-DTBDT with increased rigidness core were designed and prepared by FeCl3 oxidative polymerization. Step by step strengthening the rigidity of those polymers, stacking morphology(planar, three-dimensional mesh pattern, spherical) and Brunauer–Emmett–Teller (BET) surface areas have large improved respectively (thienyl core is 58 m² g⁻¹, phenyl core is 869 m² g⁻¹ and BDT fused ring is 1140 m² g⁻¹.), at the same time carbon dioxide uptake capacity was enhanced from 2.1 wt% to 12.1 wt% at 1.1 bar and 273 K, accompanied with the adsorption heat increased from 17 to 37 KJ mol⁻¹. Molecular-level models were developed and shown the same trend with the experiments results. Rational skelectal rigidity can counteract with nanostructural packing and avoid the nanoporous collapsing in organic microporous polymers.
Direct arylation polymerization between derivatives of dibromodiketopyrrolopyrrole (DPP) and thienoisoindigo (TIIG) resulted in two π-conjugated copolymers with average molecular weights up to 24.0 kDa and bandgaps as low as 0.8 eV. The structural analysis of the obtained two polymers revealed well-defined alternating conjugation backbones without obvious structural defects. The introduction of hexyl-group in the β-position of thiophene rings in the DPP units not only reduces the bandgap of conjugated polymer compared to a similar polymer containing bare-thiophene flanked DPP but also affects polymer morphology in thin films. P-type charge-transport characteristics were observed for two polymers in organic field-effect transistors with comparable hole mobilities. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017
Among the various molecular designs developed for the synthesis of conjugated polymers and small molecules for optoelectronic applications, the donor: acceptor (D-A) approach is the most widely explored method over the past decades. Through the covalent linkage of electron-rich and electron-deficient units, a plethora of medium-low band gap materials has been developed and tested in organic photovoltaic devices. In particular, the quinoxaline aromatic structure and its derivatives are among the most studied electron deficient aromatic units used in D-A structures. Quinoxaline based materials are endowed with characteristics that are useful for large scale production in real world applications, such as easy synthetic procedures and excellent stability in air. Moreover, the use of quinoxaline based polymers/small molecules in bulk heterojunction (BHJ) devices led to power conversion efficiencies over 9%. Considering the potential of quinoxaline based materials, this review gathers together quinoxaline based polymers and small molecules reported in the literature during the last 5 years, summarizing and discussing the structure-properties relationships for this class of organic semiconductors, aiming to serve as a background and to promote efforts for the further development of new quinoxaline derivatives with improved and advanced properties for future applications.
The direct arylation synthesis of π-conjugated network polymers (conjugated microporous polymers: CMP) containing fluoroarene and triazine moieties was successfully achieved. The direct arylation of 1,2,4,5-tetrafluorobenzene or 1,3,5-trifluorobenzene with a tribromoarene having a triazine core under two reaction conditions (Conditions a: in DMAc, Conditions b: in toluene) gave four types of CMPs (CMP1a, CMP1b, CMP2a and CMP2b). Brunauer-Emmett-Teller (BET) surface area of CMP2a and CMP2b was higher than that of CMP1a and CMP1b because of a higher number of branches. The solvents used for the direct arylation polycondensation thus strongly affected the structure of the resulting CMPs.
A narrow bandgap D-A conjugated polymer based on 5H-dithieno [3,2-b:2′,3'-d]pyran alternating with 5,6-difluoro-2,1,3-benzothiadiazole (denoted as PDFBT-alt-DTP) was synthesized via direct C-H arylation polymerization (DAP) as an atomically efficient protocol. The optimal reaction condition for the DAP gave the target polymers with moderate number-average molecular weights (Mn) using optimized catalytic condition of Pd2 (dba)3/(o-MeOPh)3P/PivOH/K2CO3 in o-xylene. UV-vis-NIR absorption spectra of the obtained polymers show the presence of aggregation and interchain interaction in thin films. ¹H-NMR spectroscopic analysis indicates good C-H selectivity corresponding to an alternating strong-donor-alt-strong-acceptor conjugated backbone. The hole mobility of the resulting polymers in a magnitude of 10⁻⁴ cm²V⁻¹s⁻¹ was reached in bottom-gate top-contact field-effect transistors fabricated and tested under ambient conditions.
Organic π-conjugated small molecules and polymers, owing to their light-weight, solution-processibility, mechanical flexibility, and large synthetic variety for finely tunable structures and properties, are promising semiconducting materials for a new generation of optoelectronic devices such as light-emitting diodes (LEDs), field-effect transistors (FETs), photovoltaic devices and sensors. A vast library of π-conjugated systems have been synthesized through conventional tools of couplings (e.g. Suzuki coupling, Stille coupling) and have been used in the fabrication of organic optoelectronic devices. In recent years an emerging synthetic technique called direct C-H arylation has been extensively studied as a facile, atom-efficient and environmentally benign pathway for the synthesis of conjugated polymers and small molecules. C-C bond formation between two heteroaryls can be carried via the activation of C-H bonds in a transition-metal catalytic cycle, thereby overcoming additional pre-functionalization steps involving toxic reagents. Direct arylation has been applied to a broad range of monomers and its reaction conditions have been optimized to produce defect-free polymers as well as small molecules that exhibit performances comparable with those made from conventional reactions. In this review, we summarize the recent progress in synthesis of conjugated small molecules, linear polymers and porous polymers by direct C-H arylation. In particular, small molecules and linear polymers based on benzothiadiazole (BT), diketopyrrolopyrrole (DPP), napththalenediimide (NDI), isoindigo (IG), thienoisoindigo (TIIG) and thienothiadiazole (TTD) are discussed in detail. Device performances of some representative polymers synthesized via direct arylation polymerization (DAP) in FETs and bulk heterojunction solar cells are summarized. We finally discuss the present challenges and perspectives of DAP towards future “greener” and more industrially scalable synthesis of π-conjugated semiconducting polymers for a variety of applications.
Direct arylation polymerization (DAP) enabled facile synthesis of a narrow bandgap donor–acceptor conjugated polymer (PDFBT-Th4) composed of alternating 5,6-difluoro-2,1,3-benzothiadiazole and alkyl-quaternarythiophene. The optimized reaction condition of DAP catalyzed with Pd(OAc)2/(o-MeOPh)3P/PivOH/K2CO3 in o-xylene led to the target polymer with a number-average molecular weight (Mn) of 14.6 kDa without noticeable homocoupling or β-branching defects. UV-vis absorption spectra of PDFBT-Th4 indicate strong interchain aggregation in films. While the C-H selectivity and the alternating polymer structure of PDFBT-Th4 synthesized via DAP are comparable to those of the same type polymers synthesized via Stille coupling, the batch of PDFBT-Th4 synthesized via optimal DAP, despite its lower Mn, showed higher hole mobility in field effect transistors and larger power conversion efficiency in organic solar cell devices. These results further demonstrate the promising potential of DAP for efficient synthesis of high-performance D-A conjugated polymers for broad optoelectronic applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017.
Near-infrared (NIR) light-responsive hydrogels are important for biomedical applications such as remotely controlled release, but the NIR agents previously used have been largely limited to heavy-metal inorganic materials such as gold nanoparticles. In this article, we report a new type of NIR photothermal responsive hydrogels, which could undergo structural changes in response to NIR light for biomedical applications in drug delivery and controlled release. The hydrogels synthesized by integrating a narrow bandgap semiconductor polymer poly(diketopyrrolopyrrole-alt-3,4-ethylenedioxythiophene) (PDPPEDOT) with polymerization of N-isopropylacrylamide (NIPAM) show rapid and reversible mechanical shrinkage upon NIR light irradiation and can serve as carriers for anticancer drug loading and spatial/temporal control of drug release. These stimuli-responsive hydrogels, which can be prepared into different sizes and shapes, integrate photothermal property and hydrogel characteristics, can provide on-demand, repeated, remotely controlled drug delivery for biomedical applications such as cancer therapy.
Direct (hetero)arylation polymerization (DHAP) has recently been established as an environmentally benign method for the preparation of conjugated polymers. This synthetic tool features the formation of C-C bonds between halogenated (hetero)arenes and simple (hetero)arenes with active C-H bonds, thereby circumventing the preparation of organometallic derivatives and decreasing the overall production cost of conjugated polymers. Since its inception, selectivity and reactivity of DHAP procedures have been improved tremendously through the careful scrutinity of polymerization outcomes and the fine-tuning of reaction conditions. A broad range of monomers, from simple arenes to complex functionalized heteroarenes, can now be readily polymerized. The successful application of DHAP now leads to nearly defect-free conjugated polymers possessing comparable, if not slightly better, characteristics than their counterparts prepared using classical cross-coupling methods. This comprehensive review describes the mechanisms involved in this process from experimental and theoretical standpoints, presents an up-to-date compendium of materials obtained by this means, and exposes its current limitations and challenges.
Conjugated porous polymers with narrow bandgaps are important for light harvesting in the near infrared region, but are limited by the availability of the appropriate building blocks and synthetic tools. Here we report a series of narrow bandgap conjugated porous polymers synthesized by facile direct arylation polymerization of thiophene-flanked thienothiadiazole with multibrominated monomers with different geometries. The polymer products show strong light absorption in the near infrared region, corresponding to narrow optical bandgaps below 1.3 eV. Under the same polymerization conditions, the morphologies, porosities and optoelectronic properties of the resulting polymers are determined by the chemical structures of the aryl bromides. The synthetic protocol of direct arylation polymerization and the structure-property relationship established in these narrow bandgap conjugated porous polymers will be important for rational material design towards applications such as gas separation/storage and photocatalysis.
A series of narrow-bandgap polymers based on an alkyl-thiophene-flanked naphthalene diimide (TNDI) were synthesized through direct arylation polycondensation. The 1H NMR spectra indicate all polymers correspond to an alternating copolymer structure with good regioregularity. Their photophysical, electrochemical, thermal and charge transport properties are characterized. Among all of the synthesized polymers, the copolymer consisting of alternating TNDI and 4,6-di-(2-thienyl)thieno[3,4-c][1,2,5]thiadiazole performs the best in the thin film transistors, with a moderate hole mobility of 4.6 × 10-3 cm2 V-1 s-1 under ambient condition.
Thiophene-flanked benzothiadiazole derivatives (DTBTs) have been among the most widely used building blocks for synthesis of a myriad of high-performance conjugated polymers for applications such as optoelectronic devices, sensing and bioimaging. We first report that these building blocks were able to be synthesized via a facile and straightforward method called direct arylation coupling. Our optimization of Pd2dba3-catalyzed direct arylation coupling gave DTBTs with comparable yield to that of Suzuki or Stille coupling reaction. DTBTs were further polymerized with fluorene dibromide via direct arylation polycondensation to give well-defined alternating polymers. One-pot direct arylation polymerizations were also carried out between benzothiadiazole dibromide, fluorene dibromide and thiophene derivatives, to form DTBTs-containing random copolymers. These random copolymers showed typical multichromophores characteristics. The property difference between the alternating polymers and random polymers were evaluated.
This article describes the synthesis of donor–acceptor (D–A) type copolymers based on benzo[1,2-b:4,5-b′]dithiophene and 2,1,3-benzothiadiazole via direct-arylation cross-coupling polycondensation. To achieve high performance polymerization, we have systematically investigated the reaction factors including catalysts, solvents, ligands, bases, additives, concentration of reactants and phase transfer agents. In particular, 1,2-dimethylbenzene (ODMB), as a nonpolar high boiling point solvent, is a superior medium to perform this direct-arylation polymerization. In this nonpolar aromatic solvent, Pd2dba3/(o-MeOPh)3P, accompanied with a base potassium carbonate and an additive pivalic acid, serves as an efficient catalyst system to obtain high-quality polymers. Our optimized condition gave the polymer with a weight-average molecular weight (Mw) as high as 60 kg mol−1 in nearly quantitative yield and excellent C–H selectivity.
Transition-metal-catalyzed aryl-aryl coupling though C-H bonds activation, termed direct arylation, has been widely used in synthesis of a broad range of small molecules. In contrast to traditional coupling methods such as Suzuki coupling and Stille coupling, di-rect arylation does not involve tedious preparation of unstable, toxic organometallic reagents. Despite these advantages, direct arylation has not been applied to synthesis of -conjugated polymers until recently. In this perspective, we summarize the progress of direct aryla-tion polymerization for synthesis of various -conjugated polymers, including homopolymers of polythiophene derivatives and donor-acceptor alternating copolymers. We also discuss present challenges and future directions of this nascent methodology of polymerization for synthesis of functional -conjugated polymers that can find applications in optoelectronic devices such as solar cells and field effect transistors.
We report the synthesis and first electronic characterization of an atomically thin two dimensional pi-conjugated polymer. Polymerization via Ullmann coupling of a tetrabrominated tetrathienoanthracene on Ag(111) in ultra-high vacuum (UHV) produces a porous 2D polymer network that has been characterized by scanning tunnelling microscopy (STM). High-resolution X-ray photoelectron spectroscopy (HRXPS) shows that the reaction proceeds via two distinct steps: dehalogenation of the brominated precursor, which begins at room temperature (RT), and C-C coupling of the resulting Ag-bound intermediates, which requires annealing at 300C. The formation of the 2D conjugated network is accompanied by a shift of the occupied molecular states by 0.6 eV towards the Fermi level, as observed by UV photoelectron spectroscopy (UPS). A theoretical analysis of the electronic gap reduction in the transition from monomeric building blocks to various 1D and 2D oligomers and polymers yields important insight into the ef
The beginning of the twenty-first century has witnessed significant advances in the field of C-H bond activation, and this transformation is now an established piece in the synthetic chemists' toolbox. This methodology has the potential to be used in many different areas of chemistry, for example it provides a perfect opportunity for the late-stage diversification of various kinds of organic scaffolds, ranging from relatively small molecules like drug candidates, to complex polydisperse organic compounds such as polymers. In this way, C-H activation approaches enable relatively straightforward access to a plethora of analogues or can help to streamline the lead-optimization phase. Furthermore, synthetic pathways for the construction of complex organic materials can now be designed that are more atom- and step-economical than previous methods and, in some cases, can be based on synthetic disconnections that are just not possible without C-H activation. This Perspective highlights the potential of metal-catalysed C-H bond activation reactions, which now extend beyond the field of traditional synthetic organic chemistry.
Thienoisoindigo (TIIG) has emerged as an attractive building block for high-performance organic optoelectronic devices. Here we report the first synthesis of a series of π-conjugated TIIG-based small molecules and alternating copolymers via direct C–H arylation, which enables the efficient synthesis without use of flammable and toxic orgametallic reagents in fewer steps compared Suzuki and Stille coupling. The direct arylation coupling between TIIG and two respective mono-bromo aryl reactants clearly shows that the α-H is more reactive than the β-H in the thiophene unit of TIIG. The high regioselectivity of TIIG monomer warrants the successful synthesis of high-quality alternating copolymers with minimal structural defects. PTIIG-BT polymer synthesized via direct arylation polymerization (DAP) showed comparable molecular weight and hole mobility than the same polymer previously synthesized via Suzuki coupling. Moreover, the two new polymers (PTIIG-TF and PTIIG-2FBT) synthesized via DAP showed hole mobility up to 10−3 cm2 V−1 s−1 in FET devices fabricated and tested under ambient conditions. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016
We report the synthesis of well-defined poly(3,3⌄-didodecyl-2,2′:5′,2″:5″,2⌄-quaterthiophene) (PQT12) from a direct heteroarylation polymerization (DHAP) of 5-bromo-3,3⌄-didodecyl-2,2′:5′,2″:5″,2⌄-quaterthiophene (monomer A) and 5-bromo-3′,4″-didodecyl-2,2′:5′,2″:5″,2⌄-quaterthiophene (monomer B). Experiments with different catalysts, ligands, additives, and solvents have revealed that the utilization of Herrmann-Beller catalyst and P(o-NMe2Ph)3 can lead to selective thiophene-thiophene couplings. In this regard, solid-state optical and thermal measurements were particularly useful to detect the presence of β-branching and indicate that minor molecular defects can induce important changes within the supramolecular organization. We also highlight the fact that steric protection around unsubstituted β-positions of α-bromothiophene units is needed to obtain a good selectivity of the cross-couplings at the α-positions. This can be achieved by the presence of a substituent at an adjacent β-position or the utilization of a bulky acidic additive (i.e., neodecanoic acid) in the catalytic system. These synthetic procedures applied to both monomers have led to PQT12 samples showing essentially the same optical and thermal properties and are comparable to those observed with their analogues prepared from chemical oxidation or Stille coupling. (Chemical Equation Presented).
The synthesis of an ambipolar π-conjugated copolymer consisting of alternating diketopyrrolopyrrole and tetrafluorobenzene via direct arylation polymerization (DAP) is reported. Two different combinations of monomers are investigated under various catalytic conditions for DAP. The target polymer obtained under an optimized catalytic condition shows minimal structural defects, a number-average molecular weight of 33.2 kDa, and balanced electron and hole mobility of 1 × 10(-2) cm(2) V(-1) S(-1) in the organic field-effect transistors fabricated and tested under ambient conditions.
3D frameworks are important because of their potential to combine the advantageous properties of porous materials with those associated with polymers. A series of novel 3D aromatic frameworks are presented that incorporate the heterocycles thiophene, selenophene, and tellurophene. The specific surface area and pore width of frameworks depends on the element that is used to build the framework. Optoelectronic properties are element-dependent, with heavy atoms red-shifting the optical properties and decreasing the energy gap of the solid. The metalloid nature of tellurophene allows the properties of this material to be tuned based on its oxidation state, even as an insoluble solid. The incorporation of the optoelectronic active thiophene, selenophene, and tellurophene units and the effect that they have on properties was studied. A supercapcitor device was fabricated using these frameworks, showing that these 3D frameworks are promising for optoelectronic uses.
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Photocatalytic hydrogen production from water offers an abundant, clean fuel source, but it is challenging to produce photocatalysts that use the solar spectrum effectively. Many hydrogen-evolving photocatalysts are active in the ultraviolet range, but ultraviolet light accounts only 3% of the energy available in the solar spectrum at ground level. Solid-state crystalline photocatalysts have light absorption profiles that are a discrete function of their crystalline phase, and that are not always tunable. Here, we prepare a series of amorphous, microporous organic polymers with exquisite synthetic control over the optical gap in the range 1.94-2.95 eV. Specific monomer compositions give polymers that are robust and effective photocatalysts for the evolution of hydrogen from water in the presence of a sacrificial electron donor, without the apparent need for an added metal co-catalyst. Remarkably, unlike other organic systems, the best performing polymer is only photoactive under visible rather than ultraviolet irradiation.
Direct arylation (DA) is emerging as a highly promising method to construct inexpensive conjugated materials for large-area electronics from simple and environ-mentally benign building blocks. Here, we show that exclusive α-C−H selectivity is feasible in the DA of π-extended monomers having unsubstituted thiophene or furan units, leading to fully linear materials. Two new naphthalene diimide-based conjugated copolymersP(FuNDIFuF 4) and P(ThNDIThF 4), composed of naphthalene diimide (NDI), furan (Fu) or thiophene (Th), and tetrafluorobenzene (F 4)are synthesized. Insight into structure−function relationships is given by density functional theory (DFT) calculations and variety of experimental techniques, whereby the effect of the heteroatom on the optical, structural, and electronic properties is investigated. The use of furan (Fu) allows for enhanced solubilities, a smaller dihedral angle between NDI and Fu as a result of the smaller size of Fu, and a smaller π−π-stacking distance in the solid state. P(FuNDIFuF 4) also exhibits a more edge-on orientation compared to P(ThNDIThF 4). Despite these advantageous properties of P(FuNDIFuF 4), P(ThNDIThF 4) exhibits the highest electron mobility: ∼1.3 cm 2 /(V s), which is a factor of ∼3 greater than that of P(FuNDIFuF 4). The enhanced OFET performance of P(ThNDIThF 4) is explained by reduced orientational disorder and the formation of a terrace-like thin-film morphology.
Low band-gap conjugated microporous polymers (CMPs) based on benzothiadiazole (BTZ) and thiophene-benzothiadiazole-thiophene (TBT) functional groups are prepared. The polymers show moderate surface areas and broad light absorption covering the whole visible light region. Fluorescence of one of the polymers can be readily quenched by the in situ blending of fullerene.
We review the design and use of microporous polymers for pre- and post-combustion capture of CO2. Microporous organic polymers are promising candidates for CO2 capture materials. They have good physicochemical stabilities and high surface areas. Ultrahigh-surface-area microporous organic polymers could find use in pre-combustion capture, while networks with lower surface areas but higher heats of sorption for CO2 might be more relevant for lower pressure, post-combustion capture. We discuss strategies for enhancing CO2 uptakes including increasing surface area, chemical functionalization to provide high-enthalpy binding sites and the potential for pore size tuning. © 2013 Society of Chemical Industry
Donor–acceptor alternating copolymers with chlorine atoms on the backbone are synthesized via a straightforward Stille polycondensation. Thiophene and chlorine‐substituted 2,3‐diphenylquinoxaline are chosen as the donor and acceptor moieties, respectively. Compared with the corresponding non‐substituted and fluorine‐substituted analogues, which are also synthesized for systematical studies, the chlorine‐bearing copolymer exhibits the deepest lowest unoccupied molecular orbital (LUMO). The highest occupied molecular orbital (HOMO) level of the chlorine‐bearing copolymer can be modified by applying different donor moieties. Additionally, these chlorine‐bearing copolymers show low self‐absorption and large Stokes Shift. Conjugated polymers bearing chlorine atoms on the backbone are synthesized in a straightforward manner via Stille polycondensation. The chlorine‐bearing polymers exhibit deeper lowest unoccupied molecular orbital (LUMO) levels than non‐substituted and fluoride polymers because the chlorine atoms cause a localized LUMO. The highest occupied molecular orbital (HOMO) level of the chlorine‐bearing copolymers can be individually modified by applying different donor moieties.
Considering the high reactivity of the C–H bonds in fluorobenzenes for direct arylation and special properties of fluorinated polymers, herein, synthesis of fluorinated porous organic polymers via direct C–H arylation polycondensation is explored. The obtained polymers (FPOP-1 and FPOP-2) are well characterized and show high porosities with Brunauer–Emmett–Teller specific surface area of above 1000 m2 g–1. Different pore size distribution (PSD) profiles of porous polymers can be obtained by selecting different core constructing monomers. FPOP-2 exhibits a relatively narrower PSD with the dominant pore size at about 0.63 nm, which is more suitable for adsorption of small gas molecules (H2, CO2, and CH4) than FPOP-1. As a porous fluorinated hydrophobic material, FPOP-2 possesses high adsorption ability for toluene (976 mg g–1 at saturated vapor pressure and room temperature) due to its high porosities and binding affinities between the guest molecules and the host network. The good sorption capacity of FPOP-2 for toluene makes it show potential applications in elimination of harmful small aromatic molecules in the environment.
Porous organic polymers (POPs), a class of highly cross-linked, amorphous polymers possessing micropores, have recently emerged as a versatile platform for the deployment of catalysts. These materials can be divided into three major classes: POPs that incorporate rigid well-defined homogeneous catalysts as building blocks, POPs that can be modified post-synthesis, and POPs that encapsulate metal particles. This perspective article summarizes the recent developments in POP-based catalysis and outlines the potential of POPs as platforms of heterogeneous catalysts along with some of the challenges.
A family of four poly(3-hexylthiophene) (P3HT) based copolymers containing 5, 10, 15, and 20% of 3-cyanothiophene (CNT) incorporated in a random fashion with a regioregular linkage pattern (P3HT-CNT) were successfully synthesized via direct arylation polymerization (DArP). Unique reaction conditions, previously reported for P3HT, were used, which employ very low loadings of Pd(OAc)2 as a catalyst and an inexpensive bulky carboxylic acid (neodecanoic acid) as an essential part of the palladium catalytic center. The chemical structures and optoelectronic properties of DArP P3HT-CNT polymers were found to be similar to those of previously investigated P3HT-CNT polymers synthesized via Stille polycondensation. All polymers are semicrystalline with high hole mobilities and UV–vis absorption profiles that resemble P3HT, while the polymer highest occupied molecular orbital (HOMO) level decreases with increasing content of cyanothiophene in both DArP and Stille P3HT-CNT polymers. In photovoltaic devices with a PC61BM acceptor, DArP P3HT-CNT copolymers showed slightly lower open-circuit voltages (Voc) than their Stille P3HT-CNT analogues but similar fill factors (FF) and significantly enhanced short-circuit current densities (Jsc), leading to overall power conversion efficiencies for the DArP polymers that rivaled or exceeded those of the Stille polymers. This work further emphasizes the generality and relevance of DArP for the synthesis of conjugated polymers for use in organic solar cells and the attractive simplicity and ease of synthesis of random conjugated polymers.
Alternating conjugated polymers of ethylenedioxythiophene and fluorene are prepared using three different synthetic methods to investigate the effects of these synthetic methods on the purity, field-effect transistor (FET) performance, and organic photovoltaic (OPV) performance of the polymer. In this study, microwave-assisted direct arylation polycondensation is used to obtain a high-purity, high-molecular-weight (147 kDa) polymer. This pure polymer exhibits a high FET hole mobility of 1.2 × 10−3 cm2 V−1 s−1 and high OPV performance with a power conversion efficiency of 4%, even though the polymer forms an amorphous film, which absorbs in a limited region of the spectrum.
We report here the synthesis of conjugated microporous polymers (CMPs) based on pyrene building units. The networks are both microporous and highly luminescent. The emission colour and resulting band gap can be fine tuned by introducing different comonomers and by varying the monomer distribution (statistical versus alternating). These materials might find applications in organic electronics, photocatalysis, optoelectronics, or in sensing technologies.
The coupling of aryl halides with catalytically activated aryl C-H bondsprovides a desirable and atom-economical alternative to standard cross-coupling reactions for the construction of new C-C bonds. The reaction, termed direct (hetero)arylation, is believed to follow a base-assisted, concerted metalation-deprotonation (CMD) pathway. During this process, carboxylate or carbonate anions coordinate to the metal center, typically palladium, in situ and assist in the deprotonation transition state. Researchers have employed this methodology with numerous arenes and heteroarenes, including substituted benzenes, perfluorinated benzenes, and thiophenes. Thiophene substrates have demonstrated high reactivity toward C-H bond activation when appropriately substituted with electron-rich and/or electron-deficient groups. Because of the pervasive use of thiophenes in materials for organic electronics, researchers have used this chemistry to modularly prepare conjugated small molecules and, more recently, conjugated polymers. Although optimization of reaction conditions such as solvent system, phosphine ligand, carboxylate additives, temperature, and time is necessary for efficient C-H bond reactivity of each monomer, direct (hetero)arylation polymerization (DHAP) can afford high yielding polymeric materials with elevated molecular weights. The properties of these materials often rival those of polymers prepared by traditional methods. Moreover, DHAP provides a facile means for the synthesis of polymers that were previously inaccessible or difficult to prepare due to the instability of organometallic monomers. The major downfall of direct (hetero)arylation, however, is the lack of C-H bond selectivity, particularly for thiophene substrates, which can result in cross-linked material during polymerization reactions. Further fine-tuning of reaction conditions such as temperature and reaction time may suppress these unwanted side reactions. Alternatively, new monomers can be designed where other reactive bonds are blocked, either sterically or by substitution with unreactive alkyl or halogen groups. In this Account, we illustrate these methods and present examples of DHAP reactions that involve the preparation of common homopolymers used in organic electronics (P3HT, PEDOT, PProDOT), copolymers formed by activation of electron-rich (bithiophene, fused bithiophenes) and electron-deficient monomers (TPD, 1,2,4,5-tetrafluorobenzene, 2,2'-bithiazole). Our group is optimizing these reactions and developing ways to make DHAP a common atom-economical synthetic tool for polymer chemists.
Conjugated microporous polymers (CMPs) with controlled specific surface area have been prepared through Sonogashira-Hagihara cross-coupling reactions in the presence of silica nanoparticles as templating agents. The CMPs act as heterogeneous photosensitizers for producing singlet oxygen in a continuous flow synthesis.
A straightforward synthesis of the fused-aromatic dione benzo[1,2-b:6,5-b']dithiophene-4,5-dione (BDTD) has been developed. This fused-aromatic dione was subjected to various chemical transformations to generate diverse molecules with potential use in π-conjugated materials for organic electronics.
The past decade has seen the development of microporous materials (i.e., materials containing pores of dimensions <2 nm) derived wholly from organic components. Here we review this nascent area with a particular emphasis on amorphous polymers that possess intrinsic microporosity (IM), which is defined as microporosity that arises directly from the shape and rigidity of component macromolecules. Although IM can be readily identified within soluble non-network polymers and oligomers, for network polymers it is harder to differentiate IM from template effects that are responsible for the microporosity within hyper-cross-linked networks. The numerous examples of microporous polymers assembled from rigid monomers by the formation of rigid linking groups are surveyed and their IM assessed. The potential applications of these materials are highlighted.
Two flavors of π: Semiconducting π-conjugated polymers may open new opportunities for the fabrication of ecofriendly, inexpensive optoelectronic devices. These materials can be prepared by direct arylation polycondensation, a straightforward approach that generates little waste and no toxic by-products.
Highly microporous element org. frameworks were synthesized by the Pd catalyzed Suzuki coupling reaction. The crosslinked polymers show sp. surface areas of up to 1380 m2/g with strong hydrophobic character. Thus, they are interesting for the adsorption of nonpolar substances. By variation of the org. linkers, the modular concept of the materials in analogy to the metal-org. frameworks is demonstrated. The polymeric materials have thermal stability up to 573 °K and show no decompn. in aq. environment, allowing excellent handling and processing. The polymers are accessible by a basic synthetic approach, and by their chem. and thermal stabilities they may provide adequate properties for applications in many fields, esp. in adsorptive sepn. processes and storage of nonpolar gases. [on SciFinder(R)]
Porous organic polymers (POPs), a class of highly crosslinked amorphous polymers possessing nano-pores, have recently emerged as a versatile platform for the deployment of catalysts. The bottom-up approach for porous organic polymer synthesis provides the opportunity for the design of polymer frameworks with various functionalities, for their use as catalysts or ligands. This tutorial review focuses on the framework structures and functionalities of catalytic POPs. Their structural design, functional framework synthesis and catalytic reactions are discussed along with some of the challenges.
This Review aims to give an overview of recent research in the area of porous, organic-inorganic and purely organic, functional materials. Possibilities for introducing organic groups that exhibit chemical and/or physical functions into porous materials will be described, with a focus on the incorporation of such functional groups as a supporting part of the pore walls. The number of organic groups in the network can be increased such that porous, purely organic materials are obtained. Pores for thought: This Review describes porous functional materials in which the organic groups act as a part of the pore wall. The focus is on functional mesoporous organosilicas as well as meso- and microporous polymers. The large number of functional groups in such porous materials allows, for example, a new approach to bridging the gap between homogeneous and heterogeneous catalysis.
The microporosity of two microporous polymer networks is investigated in detail. Both networks are based on a central spirobifluorene motif but have different linker groups, namely, imide and thiophene units. The microporosity of the networks is based on the "polymers of intrinsic microporosity (PIM)" design strategy. Nitrogen, argon, and carbon dioxide were used as sorbates in order to analyze the microporosity in greater detail. The gas sorption data was analyzed with respect to important parameters such as specific surface area, pore volume, and pore size (distribution). It is shown that the results can be strongly model dependent and swelling effects have to be regarded. (129)Xe NMR was used as an independent technique for the estimation of the average pore size of the polymer networks. The results indicate that both networks are mainly ultramicroporous (pore sizes < 0.8 nm) in the dry state, which was not expected based on the molecular design. Phase separation and network defects might influence the overall network morphology strongly. Finally, the observed swelling indicates that this "soft" microporous matter might have a different micropore size in the solvent swollen/filled state that in the dry state.
The design of hydrogen storage materials is one of the principal challenges that must be met before the development of a hydrogen economy. While hydrogen has a large specific energy, its volumetric energy density is so low as to require development of materials that can store and release it when needed. While much of the research on hydrogen storage focuses on metal hydrides, these materials are currently limited by slow kinetics and energy inefficiency. Nanostructured materials with high surface areas are actively being developed as another option. These materials avoid some of the kinetic and thermodynamic drawbacks of metal hydrides and other reactive methods of storing hydrogen. In this work, progress towards hydrogen storage with nanoporous materials in general and porous organic polymers in particular is critically reviewed. Mechanisms of formation for crosslinked polymers, hypercrosslinked polymers, polymers of intrinsic microporosity, and covalent organic frameworks are discussed. Strategies for controlling hydrogen storage capacity and adsorption enthalpy via manipulation of surface area, pore size, and pore volume are discussed in detail.
magnified image
This review covers the development and advances in transition-metal-catalyzed aryl-aryl bond formation by direct arylation as well as its application to the synthesis of important compounds including natural products, pharmaceuticals, catalyst ligands and materials. Studies focused on developing milder, lower temperature direct arylation reactions are discussed in addition to recent studies that focused on the fine-tuning of catalyst systems to allow for the use of more inexpensive and industrially attractive aryl chlorides. It is emphasized that these studies will help both synthetic and material chemicals a great deal, making direct arylation a valuable tool for diverse academic and industrial applications.
Rigid wiry nets: Conjugated microporous polymer networks are formed by Sonogashira–Hagihara coupling. Although these materials are amorphous, the micropore size and surface area can be controlled by varying the length of the phenyleneethynylene struts (see picture; the network is shown in blue, and one 1,3,5‐substituted benzene node and three connected struts are highlighted with C gray and H white).
- R Dawson
- A I Cooper
- D J Adams
R. Dawson, A. I. Cooper and D. J. Adams, Polym. Int., 2013,
62, 345-352.
- R Dawson
- A I Cooper
- D J Adams
R. Dawson, A. I. Cooper and D. J. Adams, Prog. Polym. Sci.,
2012, 37, 530-563.
- P Kaur
- J T Hupp
- S T Nguyen
P. Kaur, J. T. Hupp and S. T. Nguyen, ACS Catal., 2011, 1, 819-835.
- N B Mckeown
- P M Budd
N. B. McKeown and P. M. Budd, Macromolecules, 2010, 43,
5163-5176.
- J Germain
- J M Fréchet
- F Svec
J. Germain, J. M. Fréchet and F. Svec, Small, 2009, 5, 1098-1111.
- A Thomas
A. Thomas, Angew. Chem. Int. Ed., 2010, 49, 8328-8344.
- Y Zhang
- S N Riduan
Y. Zhang and S. N. Riduan, Chem. Soc. Rev., 2012, 41, 2083-2094.
- T Ben
- H Ren
- S Ma
- D Cao
- J Lan
- X Jing
- W Wang
- J Xu
- F Deng
- J M Simmons
T. Ben, H. Ren, S. Ma, D. Cao, J. Lan, X. Jing, W. Wang, J. Xu,
F. Deng and J. M. Simmons, Angew. Chem., 2009, 121, 9621-9624.
- R Dawson
- A Laybourn
- R Clowes
- Y Z Khimyak
- D J Adams
- A I Cooper
R. Dawson, A. Laybourn, R. Clowes, Y. Z. Khimyak, D. J.
Adams and A. I. Cooper, Macromolecules, 2009, 42, 8809-8816.
- J Weber
- A Thomas
J. Weber and A. Thomas, J. Am. Chem. Soc., 2008, 130, 6334-6335.
- J X Jiang
- F Su
- A Trewin
- C D Wood
- N L Campbell
- H Niu
- C Dickinson
- A Y Ganin
- M J Rosseinsky
- Y Z Khimyak
J. X. Jiang, F. Su, A. Trewin, C. D. Wood, N. L. Campbell, H.
Niu, C. Dickinson, A. Y. Ganin, M. J. Rosseinsky and Y. Z.
Khimyak, Angew. Chem. Int. Ed., 2007, 46, 8574-8578.
- J.-X Jiang
- A Trewin
- D J Adams
- A I Cooper
J.-X. Jiang, A. Trewin, D. J. Adams and A. I. Cooper, Chem.
Sci., 2011, 2, 1777-1781.
- P F Li
- T B Schon
- D S Seferos
P. F. Li, T. B. Schon and D. S. Seferos, Angew. Chem. Int. Ed.,
2015, 54, 9361-9366.
- R S Sprick
- J.-X Jiang
- B Bonillo
- S Ren
- T Ratvijitvech
- P Guiglion
- M A Zwijnenburg
- D J Adams
- A I Cooper
R. S. Sprick, J.-X. Jiang, B. Bonillo, S. Ren, T. Ratvijitvech, P.
Guiglion, M. A. Zwijnenburg, D. J. Adams and A. I. Cooper, J.
Am. Chem. Soc., 2015, 137, 3265-3270.
- H Lim
- J Y Chang
H. Lim and J. Y. Chang, Macromolecules, 2010, 43, 6943-6945.
- A Facchetti
- L Vaccaro
- A Marrocchi
A. Facchetti, L. Vaccaro and A. Marrocchi, Angew. Chem. Int.
Ed., 2012, 51, 3520-3523.
- T Bura
- P.-O Morin
- M Leclerc
T. Bura, P.-O. Morin and M. Leclerc, Macromolecules, 2015,
48, 5614-5620.
- A Luzio
- D Fazzi
- F Nübling
- R Matsidik
- A Straub
- H Komber
- E Giussani
- S E Watkins
- M Barbatti
- W Thiel
A. Luzio, D. Fazzi, F. Nübling, R. Matsidik, A. Straub, H.
Komber, E. Giussani, S. E. Watkins, M. Barbatti and W. Thiel,
Chem. Mater., 2014, 26, 6233-6240.