Donglin Jiang

A belt-shaped, blue luminescent, and semiconducting covalent organic framework.

From a synthetic viewpoint,COFs are attractive motifs since they allow total control overstructural parameters,including composition and porosity,after appropriate topological design. Most studies to datehave focused on the development of synthetic methodologieswith the aim of optimizing pore size and surface area.

Light-Harvesting Conjugated Microporous Polymers: Rapid and Highly Efficient Flow of Light Energy with a Porous Polyphenylene Framework as Antenna

The molecular design of light-harvesting antennae requires not only the segregation of a large number of chromophore units in a confined nanospace but also the cooperation of these units in achieving highly efficient energy transduction. This article describes the synthesis and functions of a polyphenylene-based conjugated microporous polymer (PP-CMP). PP-CMP was recently designed and synthesized by Suzuki polycondensation reaction and used as an antenna for the noncovalent construction of a light-harvesting system. In contrast to linear polyphenylene, PP-CMP consists of conjugated three-dimensional polyphenylene scaffolds and holds inherent porous structure with uniform pore size (1.56 nm) and large surface area (1083 m(2) g(-1)). It emits blue photoluminescence, is capable of excitation energy migration over the framework, and enables rapid transportation of charge carrier with intrinsic mobility as high as 0.04 cm(2) V(-1) s(-1). The microporous structure of PP-CMP allows for the spatial confinement of energy-accepting coumarin 6 molecules in the pores and makes the high-throughput synthesis of light-harvesting systems with designable donor-acceptor compositions possible. Excitation of the PP-CMP skeleton leads to brilliant green emission from coumarin 6, with an intensity 21-fold as high as that upon direct excitation of coumarin 6 itself, while the fluorescence from PP-CMP itself is wholly quenched as a result of energy transfer from the light-harvesting PP-CMP framework to coumarin 6. The PP-CMP skeleton is highly cooperative, with an average of 176 phenylene units working together to channel the excitation energy to one coumarin 6 molecule, and features the energy-transfer process with quick, efficient, and vectorial character. These unique characteristics clearly originate from the conjugated porous structure and demonstrate the usefulness of CMPs in the exploration of pi-electronic functions, in addition to their gas adsorption properties thus far reported.

CMPs as scaffolds for constructing porous catalytic frameworks: a built-in heterogeneous catalyst with high activity and selectivity based on nanoporous metalloporphyrin polymers.

This article describes the synthesis and functions of a porous catalytic framework based on conjugated micro- and mesoporous polymers with metalloporphyrin building blocks (FeP-CMP). FeP-CMP was newly synthesized via a Suzuki polycondensation reaction and was developed as a heterogeneous catalyst for the activation of molecular oxygen to convert sulfide to sulfoxide under ambient temperature and pressure. FeP-CMP is intriguing because the polymer skeleton itself is built from catalytic moieties and serves as built-in catalysts, bears inherent open nanometer-scale pores that are accessible for substrates, and possesses large surface areas (1270 m(2) g(-1)) that facilitate the transformation reaction. It is highly efficient with high conversion (up to 99%) and a large turnover number (TON = 97,320), is widely applicable to various sulfides covering from aromatic to alkyl and cyclic substrates, displays high selectivity (up to 99%) to form corresponding sulfoxides, and is highly chemoselective for the oxidation of a sulfide group even in the coexistence of other oxidative functionalities. Owing to the covalent linkages between catalytic sites in the frameworks, FeP-CMP can be recycled with good retention of its porous structure and allows for large-scale transformation. These unique characteristics clearly originate from the covalent porous catalytic framework structure and demonstrate the usefulness of CMPs in the exploration of built-in heterogeneous catalysts, a new potential of these materials that have thus far been reported to exhibit noteworthy gas adsorption functions.

A Photoconductive Covalent Organic Framework: Self‐Condensed Arene Cubes Composed of Eclipsed 2D Polypyrene Sheets for Photocurrent Generation

Covalent organic frameworks (COFs) are porous crystalline materials with predesignable 2D and 3D polymer structures. Owing to the covalent linkage of the components, as well as the elaborate control of structural parameters, including porosity and composition, COFs are promising for the design of tailor-made porous materials for gas storage. 7,8] We recently reported the cocondensation of triphenylene and pyrene monomers to create a semiconducting pconjugated COF (TP-COF). The well-defined crystalline structure of COFs should have a high probability of forming a conduction path that transports charge carriers across the framework. We are interested in the synthesis of photofunctional COFs, in particular a photoconductive COF, which would require photoinduced carrier generation and carrier transportation in the framework. Crystal engineering has demonstrated that high-quality single crystals of certain p-conjugated arenes are photoconductive as the result of exciton migration over the lattice followed by charge separation at the molecule–electrode interface. To fulfill this prerequisite, we investigated an arene-based COF, which should retain a crystal-lattice-like highly ordered arene arrangement, absorb photons in the visible region, and be robust under irradiation. Herein, we report the first example of a photoconductive COF, in which sheets composed of arene building blocks lie above one another in an eclipsed arrangement (Figure 1, PPyCOF). We chose the self-condensation of pyrenediboronic acid (Figure 1a, PDBA) as the polymerization reaction for structure formation, as we anticipated that this reaction would lead to the integration of pyrene units on edges and

Conjugated Microporous Polymers as Molecular Sensing Devices: Microporous Architecture Enables Rapid Response and Enhances Sensitivity in Fluorescence-On and Fluorescence-Off Sensing

Conjugated polymers are attractive materials for the detection of chemicals because of their remarkable π-conjugation and photoluminescence properties. In this article, we report a new strategy for the construction of molecular detection systems with conjugated microporous polymers (CMPs). The condensation of a carbazole derivative, TCB, leads to the synthesis of a conjugated microporous polymer (TCB-CMP) that exhibits blue luminescence and possesses a large surface area. Compared with a linear polymer analogue, TCB-CMP showed enhanced detection sensitivity and allowed for the rapid detection of arenes upon exposure to their vapors. TCB-CMP displayed prominent fluorescence enhancement in the presence of electron-rich arene vapors and drastic fluorescence quenching in the presence of electron-deficient arene vapors, and it could be reused without a loss of sensitivity and responsiveness. These characteristics are attributed to the microporous conjugated network of the material. Specifically, the micropores absorb arene molecules into the confined space of the polymer, the skeleton possesses a large surface area and provides a broad interface for arenes, and the network architecture facilitates exciton migration over the framework. These structural features function cooperatively, enhancing the signaling activity of TCB-CMP in fluorescence-on and fluorescence-off detection.

Supercapacitive Energy Storage and Electric Power Supply Using an Aza‐Fused π‐Conjugated Microporous Framework

Supercapacitors are energy-storage and power-supply devices that are developed to meet the increasing demand for applications in powering vehicles and portable electronic devices. Supercapacitive energy storage operates on electric double layers by accumulation of charges at the electrode/ electrolyte interfaces, at which the stored energy is proportional to the capacitance of the electrodes. Therefore, a breakthrough in electrode materials holds promise for fundamental advances in supercapacitor materials. As electrode materials, activated carbon has been intensively studied with capacitances up to 270 Fg . Recently, nanostructured carbon materials such as templated carbon materials, graphenes, carbon nanotubes, aerogels, and heteroatom-hybridized carbon materials have been developed with the aim to improve the performance and exhibit capacitances of 50– 370 Fg . Despite the extensive efforts in synthesis, the rational design of supercapacitive electrodes that meet large capacitance, high energy density, and outstanding stability remains a substantial challenge. p-Conjugated microporous polymers (CMPs) are a class of porous frameworks consisting of an extended p-conjugated system and inherent nanopores. As high surface-area porous materials, CMPs emerge as a new medium for gas adsorption and have been developed as a new type of nanoreactors and heterogeneous catalysts upon the integration of catalytic sites into the skeletons. The extended pconjugated system endows CMPs with noteworthy lightemitting properties and allows the construction of lightharvesting antennae that trigger efficient, rapid, and vectorial energy funneling from the skeleton to entrapped acceptors. From a synthetic point of view, CMPs are unique because they allow the elaborate control of both skeletons and pores. In this context, a promising way to the exploration of CMPs is to combine the structural advantages of a p-conjugated system and inherent pores. Herein, we report the synthesis of such co-operative porous frameworks based on aza-fused CMPs (Scheme 1, Aza-CMPs) and highlight their functions in supercapacitive energy storage and electric power supply.

Stable, crystalline, porous, covalent organic frameworks as a platform for chiral organocatalysts

The periodic layers and ordered nanochannels of covalent organic frameworks (COFs) make these materials viable open catalytic nanoreactors, but their low stability has precluded their practical implementation. Here we report the synthesis of a crystalline porous COF that is stable against water, strong acids and strong bases, and we demonstrate its utility as a material platform for structural design and functional development. We endowed a crystalline and porous imine-based COF with stability by incorporating methoxy groups into its pore walls to reinforce interlayer interactions. We subsequently converted the resulting achiral material into two distinct chiral organocatalysts, with the high crystallinity and porosity retained, by appending chiral centres and catalytically active sites on its channel walls. The COFs thus prepared combine catalytic activity, enantioselectivity and recyclability, which are attractive in heterogeneous organocatalysis, and were shown to promote asymmetric C-C bond formation in water under ambient conditions.

Synthesis of Metallophthalocyanine Covalent Organic Frameworks That Exhibit High Carrier Mobility and Photoconductivity

Covalent organic frameworks (COFs) are a new class of porous architectures that allow the integration of organic units with atomic precision into long-range-ordered twoand three-dimensional structures. 2] From a synthetic point of view, COFs are intriguing as they allow a new degree of control of porosity, composition, and component positions. As high-surface-area materials that link elements of low atomic mass by covalent bonds, COFs exhibit considerable potential for gas adsorption applications. As the first report on COFs in 2005, several families of COFs have been reported. However, the construction of COFs has to date been limited to certain monomers, and the lack of suitable procedures that utilize other units has impeded further advances in this emerging field. To advance this field it is therefore important to extend the limited number of synthetic methods and monomer units available. Phthalocyanines are large, planar p-electronic macrocycles with broad absorption profiles that could serve as intriguing units in the construction of porous frameworks. Crystalline phthalocyanine metal–organic frameworks have been shown to be useful in applications such as gas adsorption owing to their extended porous structures. However, phthalocyanine-based porous covalent polymers are usually amorphous and disordered. The combination of phthalocyanine units into a well-defined covalent framework thus remains an undeveloped area of research, offering great potential for obtaining novel functionality depending on the particular alignment and stacking. The eclipsed stacking endows arene-based COFs with unique functionality, such as excimer emission, exciton migration, and photoresponse. Herein, we have developed a new phthalocyanine unit for the synthesis of nickel phthalocyanine-based COFs (NiPc COF; Scheme 1). The compound, based on (2,3,9,10,16,17,23,24octahydroxyphthalocyaninato)nickel(II), [(OH)8PcNi], which has four catechol pairs at peripheral phenyl rings of a phthalocyanine macrocycle. These 2D COFs provide preorganized conduction paths based on precise ordering of the phthalocyanine stack and are ideal for charge carrier transport. Herein we present the high-throughput synthesis and unique properties of the two-dimensional metallophthalocyanine-based COF. The NiPc COF was synthesized by the boronate esterification reaction of [(OH)8PcNi] and 1,4-benzenediboronic acid (BDBA) in dimethylacetamide (DMAc)/o-dichlorobenzene under solvothermal conditions (Scheme 1a). [(OH)8PcNi] has low solubility in common organic solvents owing to its large p system and highly planar structure; typical procedures for the esterification reaction does not lead to the formation of desirable crystalline COFs. With reference to a well-established solvent combination (mesitylene/dioxane) for the synthesis of boronate-linked 2D COFs, 4] we investigated the reaction using different pairs of aromatic solvents (mesitylene, toluene, and o-dichlorobenzene) with hydrophilic solvents (dioxane, dimethylformamide (DMF), and dimethylacetamide (DMAc)). Combinations and results for the esterification reaction are summarized in the Supporting Information, Figure S1. The optimal combination for the preparation of the COFs was found to be o-dichlorobenzene and DMAc. Furthermore, the ratio of o-dichlorobenzene to DMAc was varied from 1:1 to 1:9 (vol/vol) to investigate the effect on crystallinity, as monitored by powder X-ray diffraction (PXRD) measurements. A mixture of o-dichlorobenzene/DMAc (1:2 vol/vol) gave the best result, as indicated by the intensity of the PXRD signals (Supporting Information, Figure S1). The NiPc COF was synthesized as a dark green powder in 90 % yield. It is notable that this method gives a yield that is much higher than the previously reported value (48%). Fourier-transform infrared (FTIR) spectra of the NiPc COF exhibited characteristic bands that are due to the boronate ester at 1053, 1089, 1291, and 1347 cm , and a typical C=N stretch at 1480 cm 1 for the phthalocyanine units (Supporting Information, Figure S2, Table S1). Solid-state H–C CP/MAS NMR spectroscopy using a 920 MHz H NMR spectrometer at a MAS rate of 15 kHz and a [*] X. Ding, Dr. J. Guo, X. Feng, Dr. P. Maitarad, Prof. Dr. D. Jiang Department of Materials Molecular Science Institute for Molecular Science 5-1 Higashiyama, Myodaiji, Okazaki 444-8787 (Japan) Fax: (+ 81)564-59-5520 E-mail: jiang@ims.ac.jp

An Azine-Linked Covalent Organic Framework

Condensation of hydrazine with 1,3,6,8-tetrakis(4-formylphenyl)pyrene under solvothermal conditions yields highly crystalline two-dimensional covalent organic frameworks. The pyrene units occupy the vertices and the diazabutadiene (-C═N-N═C-) linkers locate the edges of rohmbic-shaped polygon sheets, which further stack in an AA-stacking mode to constitute periodically ordered pyrene columns and one-dimensional microporous channels. The azine-linked frameworks feature permanent porosity with high surface area and exhibit outstanding chemical stability. By virtue of the pyrene columnar ordering, the azine-linked frameworks are highly luminescent, whereas the azine units serve as open docking sites for hydrogen-bonding interactions. These synergestic functions of the vertices and edge units endow the azine-linked pyrene frameworks with extremely high sensitivity and selectivity in chemosensing, for example, the selective detection of 2,4,6-trinitrophenol explosive. We anticipate that the extension of the present azine-linked strategy would not only increase the structural diversity but also expand the scope of functions based on this highly stable class of covalent organic frameworks.

Two-Dimensional Covalent Organic Frameworks for Carbon Dioxide Capture through Channel-Wall Functionalization

Ordered open channels found in two-dimensional covalent organic frameworks (2D COFs) could enable them to adsorb carbon dioxide. However, the frameworks’ dense layer architecture results in low porosity that has thus far restricted their potential for carbon dioxide adsorption. Here we report a strategy for converting a conventional 2D COF into an outstanding platform for carbon dioxide capture through channel-wall functionalization. The dense layer structure enables the dense integration of functional groups on the channel walls, creating a new version of COFs with high capacity, reusability, selectivity, and separation productivity for flue gas. These results suggest that channel-wall functional engineering could be a facile and powerful strategy to develop 2D COFs for high-performance gas storage and separation.