Co-reporter:Shudan Chen, Qiaoping Li, Shiyuan Sun, Yun Ding, and Aiguo Hu
Macromolecules January 24, 2017 Volume 50(Issue 2) pp:
Publication Date(Web):January 6, 2017
DOI:10.1021/acs.macromol.6b02321
Enediyne compounds have found limited applications in polymer science and material chemistry due to the poor regioselectivity and/or the step-growth nature in their radical polymerizations. However, the cationic cyclization of enediynes exhibits a high regioselective 5-exo-dig mechanism, providing a new strategy for the synthesis of polyfulvene derivatives. The expected polymers were successfully produced by cationic polymerization of enediynes induced by CF3SO3H, and a well-defined conjugated structure was confirmed by NMR, IR, and UV–vis spectroscopy. GPC analysis shows a relatively narrow molecular weight distribution, and the molecular weight reaches up to 62.9 kDa. On the other hand, the structural features of the obtained polymers and the mechanism of the cationic polymerization were investigated through kinetic study and MALDI-TOF MS analysis, which revealed a second-order consumption of enediyne monomer and the polymerization being probably terminated through intramolecular abstraction of proton from the neighboring group.
Co-reporter:Shudan Chen;Binlei Huang;Shiyuan Sun;Dr. Yun Ding; Dr. Aiguo Hu
Asian Journal of Organic Chemistry 2017 Volume 6(Issue 6) pp:775-779
Publication Date(Web):2017/06/01
DOI:10.1002/ajoc.201700095
AbstractEnediyne compounds generally undergo a Bergman cyclization reaction under photo-irradiation conditions. In this study, we observed an unexpected [2+2] photo-cycloaddition between enediyne compounds under photo-irradiation conditions. The structure of the cycloaddition product was confirmed through NMR, HR-MS and single crystal XRD analyses. The cycloaddition was only preferred when the reaction was conducted in the solid state or under highly concentrated conditions in the solution state. In contrast, the use of dilute conditions favored the Bergman cyclization. The concentration dependence of the enediyne substrate was further confirmed by EPR and MALDI-TOF analyses of the products. Computational investigations showed that the initial step would involve the formation of a [4+4] dimer structure, which would be converted to the [2+2] product in the second step. Interestingly, the [2+2] reaction was found to be reversible back to the enediyne monomer, where it could undergo a photo-Bergman cyclization under diluted conditions, thereby providing a new method for the formation of “masked” enediynes for further applications.
Co-reporter:Shudan Chen;Shuai Huang;Chonggang Wang;Dr. Yun Ding; Dr. Aiguo Hu
Asian Journal of Organic Chemistry 2017 Volume 6(Issue 8) pp:1099-1103
Publication Date(Web):2017/08/01
DOI:10.1002/ajoc.201700136
AbstractCycloaromatization reactions of enediynes are renowned for their widespread applications and interesting reactivity characteristics. In the presence of a lithium halide and a weak acid, the cycloaromatization of cyclodeca-1,5-diyn-3-ene can be redirected away from the usual formation of a phenyl diradical towards a zwitterionic pathway. We extended this zwitterionic reaction system to other enediyne compounds and found that it offered good applicability to all-carbon systems. However, in the case of maleimide-based enediynes, only diradical (phenyl-substituted) or anionic (butyl-substituted) cyclization pathways were observed. Notably, the nucleophilic cyclization of maleimide-based enediynes that was initiated by bromide ions exhibited a previously unreported C2−C7 cyclization pattern.
Co-reporter:Youfu Wang;Shudan Chen
Topics in Current Chemistry 2017 Volume 375( Issue 3) pp:60
Publication Date(Web):22 May 2017
DOI:10.1007/s41061-017-0145-4
Synthetic polymer chemistry is a fundamental part of polymer science, and highly efficient polymerization reactions are essential for the synthesis of high-performance polymers. Development of new synthetic methods for emerging polymer science is of great importance in this regard. Bergman cyclization is a chemical process in which highly reactive aryl diradicals form from enediyne precursors, having a strong impact in a number of fields including pharmaceutics, synthetic chemistry, and materials science. Diradical intermediates stemming from enediynes can cause DNA cleavage under physiological conditions, leading to the strong cytotoxicity of many naturally occurring enediyne antibiotics. Meanwhile, diradical intermediates can quickly couple with each other to construct polyarylenes, providing a novel method to synthesize these conjugated polymers with the advantages of facile and catalyst-free operation, high efficiency, and tailored structure. Moreover, conjugated polymers generated by Bergman cyclization exhibit many remarkable properties, such as excellent thermal stability and good solubility and processability, enabling their further processing into carbon-rich materials. This review presents a brief overview of the trajectory of Bergman cyclization in polymer science, followed by an introduction to research advances, mainly from our group, in developing polymerization methods based on Bergman cyclization, taking advantages of its catalyst-free, byproduct-free, in situ polymerization mechanism to synthesize new polymeric materials with various structures and morphologies. These synthetic strategies include fabrication of rod-like polymers with polyester, dendrimer, and chiral imide side chains, functionalization of carbon nanomaterials by surface-grafting conjugated polymers, formation of nanoparticles by intramolecular collapse of single polymer chains, and construction of carbon nanomembranes on the external and internal surface of inorganic nanomaterials. These polymers with novel structural features have been used in a variety of fields, such as energy transformation, energy storage, catalyst support, and fluorescent detection. Finally, the outlook for future developments of Bergman cyclization in polymer science is presented.
Co-reporter:Qiaoping Li, Shudan Chen, Peng Zhao, Aiguo Hu
Polymer 2017 Volume 119(Volume 119) pp:
Publication Date(Web):16 June 2017
DOI:10.1016/j.polymer.2017.05.029
•Hyperbranched polymers with enediyne units are synthesized from AB2 monomers.•Fluorescent polymers are obtained after surface decoration with phenylacetylene.•Spatial locked radicals are obtained through Bergman cyclization of the HBPs.•The free radicals in 3D polymer networks are reactive towards volatile quenchers.A series of AB2 type monomers with terminal alkyne (A) and iodine (B) were synthesized from dichloromaleic anhydride by amidation with terminal alkynylamine followed by chlorine-iodine exchange reaction. Starting from these AB2 monomers, three kinds of fluorescent hyperbranched polymers with enediyne repeating units (HBEP1∼HBEP3) were synthesized via one-pot Sonogashira cross coupling polymerization reaction. The HBEPs was characterized by a variety of techniques and the degree of branching (DB) of the HBEPs were determined by 1H NMR spectroscopy. The molecular weights (Mn) of HBEPs are up to 73 kDa and the DBs are up to 0.97, close to that for a dendrimer. Due to the different degree of conjugation of these HBEPs, the HBEPs display different photo-luminescence and excitation-dependent fluorescence behavior. These HBEPs were further subjected to thermal Bergman cyclization to generate crosslinked polymeric networks with spatially locked persistent radicals. EPR experiments showed that the free radicals in these materials were stable for a long time at room temperature and can be slowly quenched when exposed to air, providing a promising application as long-term free radical cleaner.Bergman cyclization of hyperbranched enediynes for generating spatially locked persistent radicals. HBPs with embedded enediyne moieties and many iodine groups in the peripheral are synthesized through one-pot Sonogashira cross coupling reaction of AB2-type monomers and functionalized by modification with phenylacetylene to get a series of fluorescent HBPs (HBEPs). The HBEPs are further subjected to thermal Bergman cyclization, producing polymeric networks with abundant free radicals locked inside, which are stable for a long time at room temperature, and can be slowly quenched when exposed to air.Download high-res image (134KB)Download full-size image
Co-reporter:Xian-Mei Zhang, Xuesong Ding, Aiguo Hu, Bao-Hang Han
Polymer 2017 Volume 118(Volume 118) pp:
Publication Date(Web):2 June 2017
DOI:10.1016/j.polymer.2017.04.062
•Bergman cyclization-based porous organic polymers (BCPOPs) were synthesized.•BCPOPs possess high physicochemical stability and microporosity.•BCPOPs display high carbon dioxide uptake owing to their structure features.•BCPOPs exhibit excellent selectivity towards carbon dioxide over methane.Three different monomers have been used to prepare novel Bergman cyclization-based porous organic polymers (BCPOPs). The synthesis route to BCPOPs is facile and highly-effecient. Meanwhile, BCPOPs show high physicochemical stability and excellent porosities. The Brunauer–Emmett–Teller specific surface area of BCPOPs is up to 860 m2 g−1, while the carbon dioxide uptake reaches to 11.1 wt% (1.0 bar and 273 K). Additionally, BCPOPs exhibit remarkable CO2/N2 selectivity and CO2/CH4 selectivity up to 38.6 (IAST at 273 K and 1.0 bar) and 9.6 (IAST at 273 K and 1.0 bar), respectively. By employing an easy and effective synthesis procedure, the obtained polymers are believed to be promising candidates for gas storage and separation.Download high-res image (122KB)Download full-size image
Co-reporter:Yanan Dai;Peng Zhao;Lili Wang;Yun Ding
RSC Advances (2011-Present) 2017 vol. 7(Issue 41) pp:25740-25745
Publication Date(Web):2017/05/10
DOI:10.1039/C7RA03719H
Highly fluorescent soluble conjugated polymeric nanoparticles (SCPNs) were synthesized through Suzuki-type polycondensation in confined nanoreactors, resulted in well-controlled particle sizes and uniform particle-size distributions. The SCPNs showed a wide range of the fluorescence emission maximum from 380 nm to 525 nm. They were surface-functionalized with boronic acid groups, obtained the corresponding BA-SCPNs, and further applied to the detection of two physiologically important species glucose and Fe3+ based on their interactions with boronic acid groups. The fluorescence quenching efficiency reached up to 32.1% and 92.4% for glucose and Fe3+, respectively. Among these fluorescent probes, BA-SCPN 3 exhibited enhanced glucose sensitivity compared with fructose, which might own to the formation of 1 : 1 cyclic complexes with biboronic acid derivatives. Meanwhile, BA-SCPN 3 also showed superior Fe3+ selectivity compared with other metal ions probably due to the formation of metal hydroxides between Fe3+ and the abundant hydroxyl groups in the boronic acid.
Co-reporter:Peng Zhao;Yanan Dai;Yusen Wu;Lili Wang;Binlei Huang;Yun Ding
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 37) pp:5734-5740
Publication Date(Web):2017/09/26
DOI:10.1039/C7PY01233K
A combinatorial polymerization method has been exploited to prepare a library of soluble conjugated polymeric nanoparticles (SCPNs) through palladium catalyzed polycondensations in confined nanoreactors. The strategy of independent variation within two complementary families of simple and symmetrical monomers, Ax and By (x > 2, y ≥ 2), plus post-polymerization modification with variant terminal groups greatly increases the number of polymers and improves the efficiency of polymer preparation. Fluorescence properties (band gap) of the SCPNs are easily tuned by selecting the monomer units (A or B) and the terminal (T) substituents through this “TABulated synthesis” method, providing fluorescent polymers that cover the whole visible spectrum, from blue to red. This library of SCPNs is further utilized for multicolor fluorescence sensing of explosives, showing a high Stern–Volmer quenching constant (Ksv). Meanwhile, the Ksv values of the SCPNs were mapped with the variation of the T, A, and B building blocks to predict the possible SCPN member with the optimal Ksv value (Ksv up to 1.2 × 105 M−1), showing the academic significance of this method. We believe that such a combinatorial “TAB” strategy provides a straightforward method to quickly synthesize libraries of polymeric nanoparticles, which will promote widespread studies on the functional materials in interdisciplinary fields.
Co-reporter:Qin Zhu;Zhenyu Yuan;Weiqiao Qian;Yuanyuan Li;Zhiqiang Qiu;Weijun Tang;Jie Wang;Yun Ding
Advanced Healthcare Materials 2017 Volume 6(Issue 12) pp:
Publication Date(Web):2017/06/01
DOI:10.1002/adhm.201700071
A novel platform for the development of highly efficient magnetic resonance imaging (MRI) contrast agents has been demonstrated. New contrast agents are designed and produced through electrostatic self-assembly of cationic gadolinium(III) complexes onto anionic spherical polyelectrolyte brushes (SPB). The structurally well-defined SPB are composed of polystyrene core and polyacrylic acid brush layer, where numerous binding sites and confined microenvironments are available for the embedment of the gadolinium(III) contrast agents. Both in vitro and in vivo experiments show excellent biocompatibility and relaxometric performance of these SPB-based gadolinium hybrid materials. The enhanced relaxivity value is up to 86.2 mM−1 s−1 per Gd, a remarkably high record value at 1.5 T magnetic field. In vivo imaging displays a prolonged blood circulation time and massive accumulation of the contrast agents at the tumor region due to the enhanced permeability and retention effect. The SPB-based gadolinium hybrid materials not only broaden the horizons of new MRI contrast agents, but also have a great potential for tumor diagnosis.
Co-reporter:Qin Zhu, Fei Pan, Yu Tian, Weijun Tang, Yuan Yuan and Aiguo Hu
RSC Advances 2016 vol. 6(Issue 35) pp:29441-29447
Publication Date(Web):11 Mar 2016
DOI:10.1039/C6RA02654K
Fluorescence and magnetic resonance (MR) dual-modal imaging contrast agents were prepared by the self-assembly of carbon nanodots (CDs) and gadolinium(III)-containing metallosurfactants (MS). This self-assembly process, driven by facile ionic interaction between MS and CDs, provides a new method for the preparation of dual-modal contrast agents. The obtained assemblies (MS–CDs) were investigated by various characterization techniques. Zeta potential measurement validated the driving force for the self-assembly. Transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR) confirmed the formation of the aggregates, MS–CDs. The relation between zeta potential and particle size revealed the formation process of MS–CDs assemblies. It was noteworthy that the MS–CDs assemblies exhibited high relaxivity (r1 = 19.73 mM−1 s−1, at 1.5 T) for MR imaging, which was more than fourfold that of commercial agents. The stability of the MS–CDs was evaluated by relaxation study and aggregation behaviour in phosphate buffer solution (PBS). Furthermore, good photoluminescence and low cytotoxicity were observed in model cell lines, suggesting that MS–CDs have great potential for bioimaging applications.
Co-reporter:Rulin Xiong, Likun Cheng, Yu Tian, Weijun Tang, Kehan Xu, Yuan Yuan and Aiguo Hu
RSC Advances 2016 vol. 6(Issue 33) pp:28063-28068
Publication Date(Web):11 Mar 2016
DOI:10.1039/C6RA03589B
A simple and convenient method is explored for preparing high relaxivity magnetic resonance imaging (MRI) contrast agents with numerous N-oxide groups decorated on the hyperbranched precursors as ligands for the first time. Such Gd(III) containing complexes use modified hyperbranched (or linear) polyethylenimine (PEI) with polydentate amine-N-oxide carboxylate groups as the ligands and complexes with different molecular weights show sizes from 1.63 nm to 5.40 nm with the increase of the molecular weight. T1 magnetic resonance imaging experiments show that the hyperbranched MRI contrast agents have much higher relaxivity than the linear analogue. Meanwhile, with the increase of molecular weight, the relaxivity of the complexes slowly increases to 8.9 mM−1 s−1, a number much higher than that of commercial MRI contrast agent, Gd(III) diethylenetriamine pentaacetate (Gd-DTPA). The in vitro cytotoxicity test demonstrates the excellent biocompatibility of these complexes, which is essential for clinical applications.
Co-reporter:Youfu Wang, Luhua Dong, Zhiwei Zheng, Xing Li, Rulin Xiong, Jianli Hua and Aiguo Hu
RSC Advances 2016 vol. 6(Issue 15) pp:12124-12130
Publication Date(Web):22 Jan 2016
DOI:10.1039/C5RA25938J
Three Donor–π–Acceptor (D–π–A) type dyes, with triphenylamine (TPA) as electronic donor, enediyne (EDY) moiety as π linker and cyanoacrylic acid as both electronic acceptor and anchoring group, were designed and synthesized. These EDY-bridged dyes with different donor position and number are used as sensitizers in dye-sensitized solar cells (DSSCs) to study the influence of these factors on their performance. The results show that varying the donor position and number shifts the absorbance peak or enhances the absorption intensity, but does not broaden the absorption range. With two donors at both meta- and para-positions, the conjugation length in EDY-3 is broadened, meanwhile, the twisty donors with asymmetric structure endow EDY-3 retarded dye aggregation and charge recombination. Therefore, EDY-3 shows the best performance in DSSCs among the three kinds of dyes with iodide/triiodide solution as electrolyte (JSC = 12.28 mA cm−2, VOC = 730 mV, FF = 60.43% and PCE = 5.41%).
Co-reporter:Wubing Yao, Xiaochen Ma, Le Guo, Xiangqing Jia, Aiguo Hu, Zheng Huang
Tetrahedron Letters 2016 Volume 57(Issue 26) pp:2919-2921
Publication Date(Web):29 June 2016
DOI:10.1016/j.tetlet.2016.05.074
•Unprecedented high activity for α-alkylations of unactivated amides.•Mild reaction conditions and low catalyst loadings.•Broad substrate scope with respect to acetamides and alcohols.•Wide functional group compatibility.The α-alkylation of unactivated amides with alcohols is described. Using a NCP-type pincer Ir complex as the precatalyst and KOtBu as the base, the reactions of secondary or tertiary acetamides with benzyl or nonbenzyl primary alcohols occur at 80 °C, furnishing the alkylation products in good yields. This method represents a practical and green means of α-alkylation of amides in a relatively mild, efficient, and selective manner with low catalyst loadings (0.5 mol %).
Co-reporter:Binlei Huang;Peng Zhao;Yanan Dai;Sheng Deng
Journal of Polymer Science Part A: Polymer Chemistry 2016 Volume 54( Issue 15) pp:2285-2290
Publication Date(Web):
DOI:10.1002/pola.28108
ABSTRACT
Soluble conjugated polymeric nanoparticles were synthesized through Sonogashira polycondensation between different combinations of multifunctional alkynes and aryl halides in structurally well-defined mesoporous reactors. The growth of the polymeric nanoparticles was controlled by the spatial confinement of the nanoreactors, giving conjugated polymeric nanoparticles with narrow size distribution centered at 5 nm. All the obtained polymers are freely soluble in common solvents and can be fabricated into thin film. Both of the solution and thin film prepared from these polymeric nanoparticles were highly fluorescent, endowing them potential applications in light emitting and other optoelectronic fields. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2285–2290
Co-reporter:Wubing Yao, Huaquan Fang, Sihan Peng, Huanan Wen, Lei Zhang, Aiguo Hu, and Zheng Huang
Organometallics 2016 Volume 35(Issue 10) pp:1559-1564
Publication Date(Web):March 30, 2016
DOI:10.1021/acs.organomet.6b00161
We report the first Co-catalyzed borylation of aryl halides and pseudohalides with bis(pinacolato)diboron (B2pin2). The synthesis of two new Co(II) complexes of oxazolinylferrocenylphosphine ligands is described. Upon activation with LiMe, the Co complex catalyzes the borylation reactions of aryl bromides, iodides, sulfonates, arenediazonium salts, and even aryl chlorides under mild conditions, providing the borylated products in excellent to moderate yields and with high functional group tolerance.
Co-reporter:Luhua Dong, Zhiwei Zheng, Youfu Wang, Xing Li, Jianli Hua and Aiguo Hu
Journal of Materials Chemistry A 2015 vol. 3(Issue 21) pp:11607-11614
Publication Date(Web):21 Apr 2015
DOI:10.1039/C5TA01861G
The co-sensitization of N719 with conjugated polyphenylenes for dye-sensitized solar cells (DSSCs) was demonstrated. The conjugated polyphenylenes (6-BC and 7-BC), which contain two triphenylamine (TPA) groups as electron donors and carboxylic acids as adsorption groups, were prepared from thermally triggered Bergman cyclization polymerization of two maleimide-based enediynes, 6 and 7. Both the short-circuit photocurrent density (JSC) and the open-circuit voltage (VOC) of the co-sensitized DSSCs were enhanced due to the increase in light harvesting and the retardation of electron recombination and dye aggregation when N719 was co-sensitized with the conjugated polyphenylenes. The co-sensitized (7-BC + N719) DSSC showed a high efficiency of 9.68% (VOC of 750 mV, JSC of 18.18 mA cm−2 and FF of 0.71), exhibiting an improvement of 16% compared to the devices sensitized with N719 (PCE of 8.34%) alone under identical conditions.
Co-reporter:Depeng Song, Shiyuan Sun, Yu Tian, Shuai Huang, Yun Ding, Yuan Yuan and Aiguo Hu
Journal of Materials Chemistry A 2015 vol. 3(Issue 16) pp:3195-3200
Publication Date(Web):17 Feb 2015
DOI:10.1039/C4TB02018A
A pH-sensitive acyclic enediyne (1) was synthesized for efficient DNA-cleavage and tumor cell suppression. Unlike other acyclic enediynes, this novel enediyne transforms into a highly reactive enediyne (2) in an acidic environment only, which undergoes Bergman cyclization spontaneously at ambient temperature. An EPR study on the enediyne 2 confirmed the generation of free radicals through Bergman cyclization. The activated enediyne induced DNA-cleavage and exhibited cytotoxicity towards various tumor cells under the action of diradicals arising from spontaneous Bergman cyclization at physiological temperature. These findings suggest a novel strategy of anticancer drug design, where the activation of the silent compound takes place under the acidic environment inside the tumor cells.
Co-reporter:Depeng Song, Yu Tian, Shuai Huang, Baojun Li, Yuan Yuan and Aiguo Hu
Journal of Materials Chemistry A 2015 vol. 3(Issue 43) pp:8584-8588
Publication Date(Web):21 Sep 2015
DOI:10.1039/C5TB01867F
An acyclic enediyne with a furyl tethering group and two pH-sensitive orthoester groups at the alkynyl termini was synthesized. The enediyne compound yielded free radicals, which can be further trapped by other atoms, under acidic conditions at ambient temperature. It exhibited high cytotoxicity towards tumor cells, and affected normal cells much less, while showing very low cytotoxicity to both types of cells once the furan group was reacted with a dienophile, 4-phenyl-1,2,4-triazoline-3,5-dione. Confocal laser scanning microscopy experiments showed that the derivation of the furan group dictated the cytosis of the enediyne molecules. The cytotoxicity of the enediyne molecules disappeared when cytosis was hindered. The introduction of a furyl tethering group into enediyne represents a new design strategy of “intelligent” antitumor antibiotics that can distinguish tumor and normal cells.
Co-reporter:Yingying Chen, Qin Zhu, Yu Tian, Weijun Tang, Fei Pan, Rulin Xiong, Yuan Yuan and Aiguo Hu
Polymer Chemistry 2015 vol. 6(Issue 9) pp:1521-1526
Publication Date(Web):03 Dec 2014
DOI:10.1039/C4PY01562B
The assembly behavior of narrowly dispersed poly(sodium acrylate) (PAAS) of different molecular weights with Gd(III)-containing cationic metallosurfactants (MS) was investigated by DLS, TEM and relaxivity plotting. The formed polyelectrolyte–surfactant complexes (PSCs) showed different structural patterns as the charge ratio increased from micellar to vesicular structures. SEM element mapping showed the presence of the gadolinium element in these complexes. An ICP-AES analysis further quantified the contents of Gd(III) in the PSCs. T1 magnetic resonance imaging (MRI) showed that these Gd(III)-loading complexes exhibited a relaxivity of up to 21.89 mM−1 s−1, much higher than that of Omniscan® (4.64 mM−1 s−1). A higher relaxivity was achieved with PAAS of higher molecular weight at the same charge ratio. The cytotoxicity test in vitro demonstrated the excellent biocompatibility of these PSCs, which is essential for clinical application.
Co-reporter:Yong Zhang, Youfu Wang and Aiguo Hu
RSC Advances 2015 vol. 5(Issue 86) pp:70297-70301
Publication Date(Web):07 Aug 2015
DOI:10.1039/C5RA13235E
Hierarchically porous carbon nanofoams (CNFs) with uniform cavity and highly porous skeleton have been prepared via the formation of core–shell organosilica nanoparticles in one-pot reaction and subsequent Friedel–Crafts chemistry. The porosity of the CNFs, which have macroporous cavity (∼50 nm), mesoporous windows (∼12 nm) between adjacent cavities and mesoporous skeleton (∼3 nm), were facially tuned by varying the amount of phenyltriethoxysilane (PTES) used in the first step. CNFs with high surface area (>1100 m2 g−1), large pore volume (∼2 cm3 g−1) and partially graphitized skeleton exhibited good performances as supercapacitor electrode materials. The specific capacitance of the porous CNFs reached 170 F g−1 at a current density of 0.5 A g−1 in an aqueous electrolyte.
Co-reporter:Sheng Deng, Peng Zhao, Yanan Dai, Binlei Huang, Aiguo Hu
Polymer 2015 Volume 64() pp:216-220
Publication Date(Web):1 May 2015
DOI:10.1016/j.polymer.2015.02.006
•Suzuki polycondensation of multi-functional monomers (Ax + By, x > 2, y ≥ 2) were studied.•Soluble conjugated polymeric nanoparticles were produced in heterogeneous systems.•The growth of the nanoparticles was regulated by the decomposition of boronic acid.•The size of the nanoparticles was controllable by variation of the reaction condition.Conjugated hyperbranched polyphenylene nanoparticles are fabricated by cross coupling reactions between an A2 type monomer 1,4-phenylenediboronic acid (1) and B3 type monomers 1,3,5-triiodobenzene (2) and 1,3,5-tribromobenzene (3). The Suzuki-type polycondensation was conducted with a highly efficient heterogeneous catalyst to give conjugated polymeric nanoparticles which are soluble in a variety of organic solvents. The growth of the hyperbranched polyphenylenes are controlled and eventually terminated by the decomposition of the boronate terminal groups in basic aqueous media in the heterogeneous catalysis system. This method represents a new approach to produce soluble conjugated polymeric nanoparticles with simple and symmetrical monomers with more than two end groups (Ax + By, x ≥ 2, y > 2).
Co-reporter:Jian Zhi
The Journal of Physical Chemistry C 2015 Volume 119(Issue 16) pp:8530-8536
Publication Date(Web):March 27, 2015
DOI:10.1021/acs.jpcc.5b01230
Highly ordered metal oxide nanorods (MnO2, SnO2, NiO) inside mesoporous silica supported carbon nanomembranes have been applied for electroactive materials to fabricate symmetrical supercapacitors. Maximum specific capacitance of the obtained cells reaches up to 964 F g–1 in aqueous electrolyte with energy density of 33.5 Wh kg–1 for a 1 V voltage window, which are among the highest values in two electrodes supercapacitor cells employing similar metal oxide/carbon materials. This high performance is attributed from the synergic effect of the conductive carbon nanomembrane and well-ordered pseudocapacitive metal oxide nanorods.
Co-reporter:Yuxuan Zhang;Wubing Yao;Huaquan Fang;Zheng Huang
Science Bulletin 2015 Volume 60( Issue 15) pp:1316-1331
Publication Date(Web):2015 August
DOI:10.1007/s11434-015-0818-8
Olefins find widespread applications in the synthesis of polyolefins and fine chemicals. With an increasing demand for olefins, the technologies for alkane dehydrogenation have drawn much attention. Several types of heterogeneous catalysts have found applications in industry for the dehydrogenation of light alkanes, mainly ethane, propane, and butane. In the past three decades, a number of transition-metal complexes, particularly pincer-ligated iridium complexes, have been developed as the homogeneous catalysts for alkane dehydrogenations. The homogeneous catalyst systems operate under much milder conditions compared with the heterogeneous systems, and some systems exhibit good activity and high regioselectivity in dehydrogenation of alkanes longer than butane.烯烃是一种重要的有机合成原料,在聚合物制备和精细化工领域具有非常广阔的应用前景。随着近年来烯烃需求的不断增长,烷烃脱氢制烯烃技术受到研究人员的广泛关注,多种不同类型的非均相催化剂已成功应用于低碳烷烃如乙烷、丙烷以及丁烷的催化脱氢工艺。在最近三十年中,过渡金属络合物,特别是pincer结构的铱络合物,已发展成为一类优良的均相烷烃脱氢催化剂。相对于非均相催化体系,该均相体系的反应条件更加温和,并且对直链烷烃( > C4)显示出更高的脱氢活性和区域选择性。
Co-reporter:Shudan Chen
Science China Chemistry 2015 Volume 58( Issue 11) pp:1710-1723
Publication Date(Web):2015 November
DOI:10.1007/s11426-015-5460-4
The Bergman cyclization has strongly impacted on a number of fields including pharmaceutics, synthetic chemistry, and material science. The diradical intermediates stemmed from enediynes can not only cause DNA cleavage under physiological conditions but also function as monomer or initiator participants in polymer science. The homo-polymerization of enediynes through the Bergman cyclization to fabricate conjugated polymers is a fascinating strategy due to the advantages of facial operation, high efficiency, tailored structure, and catalyst-free operation. Moreover, conjugated polymers generated through the Bergman cyclization show many remarkable properties, such as excellent thermal stability, good solubility, and processability, which enables these polymers to be further manufactured into carbon-rich materials. Recent times have seen extensive efforts devoted to the application of the Bergman cyclization in polymer science and materials chemistry. A variety of synthetic strategies have been developed to fabricate structurally unique materials via the Bergman cyclization, including the fabrication of rod-like polymers with polyester, dendrimers and chiral imide side chains, functionalization of carbon nanomaterials by surface-grafting conjugated polymers, formation of nanoparticles by intramolecular collapse of single polymer chains, and the construction of carbon nanomembranes with different morphologies. Future developments involving the Bergman cyclization in polymer science, probably by altering the reaction mechanism to precisely control the microstructure of polymeric products, are also proposed in this review article.
Co-reporter:Shiyuan Sun;Luhua Dong;Depeng Song;Binlei Huang
Chinese Journal of Polymer Science 2015 Volume 33( Issue 1) pp:184-191
Publication Date(Web):2015 January
DOI:10.1007/s10118-015-1566-6
Several new enediynes with long chain alkyl groups were synthesized through Sonogashira coupling reactions between long chain alkynes and (Z)-1,2-dichloroethene. These enediynes (1) were then subjected to thermal Bergman cyclization in a refluxing diphenyl ether bath under vacuum to obtain conjugated polyphenylenes with the weight-average molecular weights up to 4.9 × 103 g·mol−1. The occurrence of Bergman cyclization was confirmed by 1H-NMR, 13C-NMR, and IR spectroscopic analysis. These polyphenylenes are fully soluble in common organic solvents and exhibit good thermal stability. The optical properties of the polyphenylenes were investigated by UV-Vis absorption and photoluminescence (PL) spectroscopies. A blue emission was observed for all these polyphenylenes.
Co-reporter:Shiyuan Sun;Binlei Huang;Fei Li;Depeng Song
Chinese Journal of Polymer Science 2015 Volume 33( Issue 5) pp:743-753
Publication Date(Web):2015 May
DOI:10.1007/s10118-015-1622-2
Chiral enediynes with pendant chiral amino ester groups are synthesized through Sonogashira reactions and subjected to thermal triggered Bergman cyclization at elevated temperatures either in bulk or in solvents to produce chiral polyphenylenes. The disappearance of enediyne monomers are evidenced by FTIR and NMR spectroscopies. The formation of polyphenylenes is further confirmed by UV-Vis and MALDI-TOF mass spectroscopies (MS). Isotope pattern analysis of the MS spectra shows that the polymers prepared in solvents are terminated by the solvent molecules, whereas the chain ends of the polymers prepared in bulk consist of considerable amount of unmasked free radicals, which is further confirmed by EPR analysis. Circular dichroism (CD) spectra of the chiral polymers show blue shifts of the Cotton peaks, indicating the occurrence of the cycloaromatization reaction. A new set of peaks mirrored at the horizontal axis show up in the long wavelength range, which are assigned to main chain chirality of the polyphenylenes.
Co-reporter:Youfu Wang and Aiguo Hu
Journal of Materials Chemistry A 2014 vol. 2(Issue 34) pp:6921-6939
Publication Date(Web):17 Jun 2014
DOI:10.1039/C4TC00988F
Carbon quantum dots (CQDs, C-dots or CDs), which are generally small carbon nanoparticles (less than 10 nm in size) with various unique properties, have found wide use in more and more fields during the last few years. In this feature article, we describe the recent progress in the field of CQDs, focusing on their synthetic methods, size control, modification strategies, photoelectric properties, luminescent mechanism, and applications in biomedicine, optronics, catalysis and sensor issues.
Co-reporter:Youfu Wang, Rulin Xiong, Luhua Dong and Aiguo Hu
Journal of Materials Chemistry A 2014 vol. 2(Issue 15) pp:5212-5217
Publication Date(Web):21 Jan 2014
DOI:10.1039/C3TA15311H
A bottom-up synthesis of three-dimensional (3D) carbon nanomembranes (CNMs) was developed through Friedel–Crafts cross-linking of phenyl self-assembled monolayers (SAMs) on silica nanospheres (SNSs) followed by high temperature treatment and template removal. The CNMs show a hierarchically 3D connected porous structure and the pore sizes are facilely tuned by varying the sizes of SNS templates. CNMs with high surface area (>1500 m2 g−1), large pore volume (∼3 cm3 g−1) and partially graphitized frameworks exhibited good performances as supercapacitor electrode materials. The specific capacitance of the porous 3D CNMs reached 202 F g−1 at a current density of 0.5 A g−1 in an aqueous electrolyte.
Co-reporter:Qinggang Tan, Chi Zhang, Ning Wang, Xiujuan Zhu, Qiang Sun, Mikkel F. Jacobsen, Kurt V. Gothelf, Flemming Besenbacher, Aiguo Hu and Wei Xu
Chemical Communications 2014 vol. 50(Issue 3) pp:356-358
Publication Date(Web):28 Oct 2013
DOI:10.1039/C3CC46149A
From an interplay of high-resolution scanning tunneling microscopy (STM) imaging and density functional theory (DFT) calculations we demonstrate that by delicately choosing the parent molecule (adenine) we are able to tune the self-assembled nanostructures of adenine derivatives which are directed by the specific intermolecular interactions provided by the adenine moiety.
Co-reporter:Shiyuan Sun, Chuanchuan Zhu, Depeng Song, Fei Li and Aiguo Hu
Polymer Chemistry 2014 vol. 5(Issue 4) pp:1241-1247
Publication Date(Web):15 Oct 2013
DOI:10.1039/C3PY00970J
Several maleimide-based enediynes are synthesized through Sonogashira coupling reactions between 3,4-diiodo-N-benzylmaleimide (3) and para-substituted phenylacetylenes (5). All these enediynes undergo thermal-triggered Bergman cyclization at elevated temperature (130–160° C) as revealed by DSC analysis. Conjugated polyphenylenes (7) are obtained by simply heating these enediynes (6) under vacuum. The occurrence of Bergman cyclization is evidenced by IR and NMR spectroscopy. The conjugated polyphenylenes are further characterized by UV-vis and MALDI-TOF mass spectroscopy (MS). Isotope pattern analysis on the MS spectra of the conjugated polyphenylenes shows that the chain ends of the polymers consist of a considerable amount of unmasked free radicals. EPR spectroscopy of the conjugated polyphenylenes confirms the existence of free radicals, which slowly fade away probably by removing active atoms (like hydrogen or halogen) from the environment.
Co-reporter:Jian Zhi, Youfu Wang, Sheng Deng and Aiguo Hu
RSC Advances 2014 vol. 4(Issue 76) pp:40296-40300
Publication Date(Web):12 Aug 2014
DOI:10.1039/C4RA06260D
Electrochemical capacitors (ECs) have traditionally been considered as standing at the opposite end against batteries in energy–power diagram. They charge and discharge faster than batteries but are limited by much lower energy density. By optimizing the pore structure of porous electrode materials, the performance of ECs could overcome this limitation. However to date, no study has addressed the complex relationship between the texture parameters of the electrode materials and the supercapacitance of ECs. Using silica-supported carbon nanomembranes, four electrode materials with similar pore geometry are generated. The electrodes with a pore size of 4.14 nm shows the highest capacitance of 305 F g−1 in aqueous electrolytes. A new model is developed to simulate the accommodation of the solvated ions at the electrode surface. The simulation reveals that the optimal capacitance of ECs can be achieved using porous carbon electrode materials with open pores of 3.0–5.0 nm.
Co-reporter:Yingying Chen;Qin Zhu;Xinghui Cui;Weijun Tang;Heng Yang; Yuan Yuan; Aiguo Hu
Chemistry - A European Journal 2014 Volume 20( Issue 39) pp:12477-12482
Publication Date(Web):
DOI:10.1002/chem.201402530
Abstract
Novel contrast agents were developed through assembling of GdIII-containing metallosurfactant (MS) with biocompatible polyelectrolytes sodium hyaluronate (HA), heparinsodium (HS) and dextran sulfate sodium (DSS). The formed polyelectrolyte–surfactant complexes showed different structural patterns as the charge ratio increased, including spherical aggregates, rod-like aggregates and network patterns in monovalent HA system, while spherical structures emerged in multivalent HS and DSS systems. Energy dispersive spectroscopy analysis and scanning electron microscopy mapping showed the presence of GdIII in these complexes. Inductively coupled plasma atomic emission spectrometry was further used to quantify the contents of GdIII in the assemblies. T1 magnetic resonance imaging showed that these GdIII-loaded complexes exhibited relaxivity of up to 63.81 mM−1 s−1, much higher than that of Ominiscan (4.64 mM−1 s−1). The cytotoxicity test in vitro demonstrated the excellent biocompatibility of these complexes, which is essential for clinical application.
Co-reporter:Sheng Deng;Dr. Jian Zhi;Xianmei Zhang;Qingqing Wu;Dr. Yun Ding; Aiguo Hu
Angewandte Chemie International Edition 2014 Volume 53( Issue 51) pp:14144-14148
Publication Date(Web):
DOI:10.1002/anie.201407387
Abstract
Soluble conjugated polymeric nanoparticles are synthesized by Suzuki-type polycondensation of two monomers (Ax + By, x>2, y≥2) in the channel of ordered mesoporous silica-supported carbon nanomembranes (nanoreactors). These synthesized soluble conjugated microporous polymers (SCMPs) exhibit uniform particle-size distributions and well-controlled particle sizes. The control of particle size stems from the fact that the polycondensations exclusively take place inside the mesochannels of the nanoreactors. Photoluminescence studies show that polymeric nanoparticles with tetraphenylethene and pyrene substructures are highly fluorescent. The combination of both physical stability and processability offered by the soluble polymeric nanoparticles makes them particularly attractive in light emitting and other optoelectronic applications.
Co-reporter:Qiang Sun ; Chi Zhang ; Zhiwen Li ; Huihui Kong ; Qinggang Tan ; Aiguo Hu ;Wei Xu
Journal of the American Chemical Society 2013 Volume 135(Issue 23) pp:8448-8451
Publication Date(Web):May 24, 2013
DOI:10.1021/ja404039t
On-surface fabrication of covalently interlinked conjugated nanostructures has attracted significant attention, mainly because of the high stability and efficient electron transport ability of these structures. Here, from the interplay of scanning tunneling microscopy imaging and density functional theory calculations, we report for the first time on-surface formation of one-dimensional polyphenylene chains through Bergman cyclization followed by radical polymerization on Cu(110). The formed surface nanostructures were further corroborated by the results for the ex situ-synthesized molecular product after Bergman cyclization. These findings are of particular interest and importance for the construction of molecular electronic nanodevices on surfaces.
Co-reporter:Benchuan Zhu, Shiyuan Sun, Youfu Wang, Sheng Deng, Guannan Qian, Meng Wang and Aiguo Hu
Journal of Materials Chemistry A 2013 vol. 1(Issue 3) pp:580-586
Publication Date(Web):06 Nov 2012
DOI:10.1039/C2TC00140C
Even after several years of research, controlled synthesis of photoluminescent carbon nanodots (C-dots) still constitutes a major challenge, and investigation of their photoluminescence (PL) mechanism remains elusive. Various top-down and bottom-up approaches have been reported lately. However, these methods usually suffer from limited control over the major factors that dictate the PL behaviour of these fascinating carbon materials. To this end, we discover a new approach to prepare C-dots from size-tunable single chain polymeric nanoparticles. Taking advantage of the state of the art living radical polymerization technique and unique features of Bergman cyclization, narrowly dispersed C-dots are prepared in a straightforward manner. PL study shows that the optimal emission wavelength of C-dots red-shifts when the size of C-dots decreases, which is different from the trends typically found in semiconductor quantum dots and C-dots prepared from graphitized materials. To clarify the PL mechanism of C-dots prepared from different sources, a theoretical study based on density functional theory is performed. Two series of model compounds, fused aromatic rings and cyclo-1,4-naphthylenes, are chosen for C-dots with different microstructures. The calculation data indicate that PL energy of C-dots is dictated by the size and microstructure of the sp2 carbon core. For a C-dot with a graphitized core, the smaller the size of the core, the higher the PL energy, while for a C-dot with an amorphous core, an inverse trend is revealed. Surface reduction experiments further show that the quantum yield of C-dots is controlled by the surface chemistry.
Co-reporter:Yingying Chen, Heng Yang, Weijun Tang, Xinhui Cui, Wei Wang, Xiangyu Chen, Yuan Yuan and Aiguo Hu
Journal of Materials Chemistry A 2013 vol. 1(Issue 40) pp:5443-5449
Publication Date(Web):07 Aug 2013
DOI:10.1039/C3TB20807A
A new Gd(III)-based metallosurfactant with double quaternary-ammonium-containing long alkyl chains was developed and subjected to the miniemulsion polymerization of vinyl monomers, giving nanosized colloids (50–110 nm) with narrow size distribution. The size of the colloid particles can be easily tuned by adjusting the feeding ratio of metallosurfactant to monomer. SEM and XPS analysis showed that the Gd(III) complexes were attached on the surface of the colloids. ICP-AES analysis further quantified the contents of Gd(III) in the miniemulsions. T1 magnetic resonance imaging (MRI) showed that these Gd(III)-loading colloids exhibited relaxivity of up to 22.77 mM−1 s−1, much higher than that of Ominiscan® (4.64 mM−1 s−1).
Co-reporter:Youfu Wang, Luhua Dong, Rulin Xiong and Aiguo Hu
Journal of Materials Chemistry A 2013 vol. 1(Issue 46) pp:7731-7735
Publication Date(Web):30 Aug 2013
DOI:10.1039/C3TC30949E
As emergent nanolights for bioimaging, catalysis, sensors, and photoelectronics, carbon dots (C-dots) have attracted much research attention. However, the practical and scalable preparation of C-dots has been less explored, even after various top-down and bottom-up approaches being reported recently. To this end, we discover a new approach to prepare C-dots by simply unzipping core–shell polymeric nanoparticles, prepared by a microemulsion polymerization. Uniformly distributed N-doped C-dots are prepared by the pyrolysis of PAN@PMMA core–shell nanoparticles at different temperatures, followed by dialysis. TEM analysis shows that many of the C-dots of 2–3 nm size are unzipped from each polymeric particle. All the purified C-dots show a bandgap-like photoluminescence (PL) behaviour, with dual emission and a stable PL between pH 5–12.
Co-reporter:Jian Zhi, Sheng Deng, Yuxuan Zhang, Youfu Wang and Aiguo Hu
Journal of Materials Chemistry A 2013 vol. 1(Issue 9) pp:3171-3176
Publication Date(Web):07 Jan 2013
DOI:10.1039/C2TA01253G
A three dimensional porous carbon nanomembrane (CNM), silica-supported CNM (SS-CNM), is developed by formation of a self-assembled monolayer of an enediyne compound on the surface of mesoporous silica (SBA-15) followed by Bergman cyclization and carbonization. The SS-CNM is applied as a conductive support for the electroactive material Co3O4 to fabricate advanced supercapacitors. A large fraction of Co3O4 clusters (66% of total weight) are impregnated in the SS-CNM host to form regularly packed nanorods with diameters of 7 nm. The specific capacitance of the supercapacitor electrode material reaches 1086 F g−1 (1645 F g−1 based on Co3O4) with aqueous electrolyte. This extraordinary high performance of the electrode material is attributed to the unique pore structure of the SS-CNM support that enhances the use of active material and shortens the transport path of ions and electrons.
Co-reporter:Liang Dong, Qiang Sun, Chi Zhang, Zhiwen Li, Kai Sheng, Huihui Kong, Qinggang Tan, Yunxiang Pan, Aiguo Hu and Wei Xu
Chemical Communications 2013 vol. 49(Issue 17) pp:1735-1737
Publication Date(Web):11 Jan 2013
DOI:10.1039/C3CC38383K
The native copper adatoms get trapped in a self-assembled molecular nanostructure which is mainly formed by the intermolecular van der Waals interactions, and two dominating specific binding modes between the adatoms and the molecules are revealed at the atomic scale by high-resolution STM imaging.
Co-reporter:Zhiwen Li;Xiujuan Zhu;Shudan Chen ; Aiguo Hu
Chemistry – An Asian Journal 2013 Volume 8( Issue 3) pp:560-563
Publication Date(Web):
DOI:10.1002/asia.201201132
Co-reporter:Kai Sheng;Huihui Kong;Zhiwen Li;Chi Zhang;Qiang Sun;Dr. Qinggang Tan;Dr. Yunxiang Pan;Dr. Aiguo Hu;Dr. Wei Xu
ChemCatChem 2013 Volume 5( Issue 9) pp:2662-2666
Publication Date(Web):
DOI:10.1002/cctc.201200955
Abstract
Catalytic reactions occurring on oxide-supported Cu and Cu-supported oxide catalysts are of fundamental interest in both industrial and scientific fields. Though the interface between Cu and oxide species has been regarded as the reaction site, the exact role of the interface in the catalytic reactions is not fully understood yet. In this work, by using a model system including CuO chains supported on Cu(1 1 0) and an organic molecule with alkynyl and aldehyde groups, we attempted to obtain a fundamental understanding of the role of the interface in the catalytic reactions. A combination of high-resolution scanning tunneling microscopy imaging and density functional theory calculations provided direct evidence at the atomic scale that the interface between the CuO chains and the Cu(1 1 0) surface is the most favorable site for the adsorption and activation of organic molecules, and the oxygen of CuO has an activity to oxidize both the alkynyl and aldehyde groups of the molecules adsorbed at the interface.
Co-reporter:Guannan Qian;Benchuan Zhu;Youfu Wang;Sheng Deng
Macromolecular Rapid Communications 2012 Volume 33( Issue 16) pp:1393-1398
Publication Date(Web):
DOI:10.1002/marc.201200199
Abstract
Hydrophilic polymeric nanoparticles are synthesized through a Bergman cyclization- mediated intramolecular chain collapse of structurally well-defined linear polymers, and then used as size-tunable nanoreactors to fabricate and encapsulate quantum dots in a one-pot reaction. Crystalline quantum dots are formed in all of these nanoreactors and visualized by transmission electron microscopy. Smaller nanoreactors produce one quantum dot each while larger nanoreactors form a number, resulting in fluorescence quenching. By controlling the molecular weight of the linear polymer precursor, a variable number of nanocrystals are fabricated and assembled in a single nanoreactor.
Co-reporter:Xiaowei Ma;Fei Li;Youfu Wang ; Aiguo Hu
Chemistry – An Asian Journal 2012 Volume 7( Issue 11) pp:2547-2550
Publication Date(Web):
DOI:10.1002/asia.201200520
Co-reporter:Benchuan Zhu, Jianguo Ma, Zhiwen Li, Jing Hou, Xin Cheng, Guannan Qian, Pai Liu and Aiguo Hu
Journal of Materials Chemistry A 2011 vol. 21(Issue 8) pp:2679-2683
Publication Date(Web):12 Jan 2011
DOI:10.1039/C0JM03143G
Polymeric nanoparticles were synthesized through Bergman cyclization mediated intramolecular chain collapse. Enediyne moieties were incorporated into linear polymers through copolymerization or post-polymerization modification. The resulted enediyne containing copolymers were then subjected to intramolecular chain collapse under ultra-dilute condition or applying a continuous addition technique. The occurrence of Bergman cyclization was confirmed with IR, NMR and DSC analysis. The intramolecular chain collapse was characterized with GPC, DSC, and AFM. Dramatic decreases of apparent molecular weights of linear copolymers were observed after Bergman cyclization. The structural diversity of enediyne precursors and mild chain collapse condition allow wide monomer selection, which facilitates preparation of a broad range of polymeric nanoparticles. Low-k dielectric thin films were prepared using polymeric nanoparticles through “porogen” approach. The packing tightness of polymeric nanoparticles showed strong influence on film formation behavior with MSSQ matrix. With tightly packed polymeric nanoparticles as sacrificial pore generators, thin films with dielectric constants of as low as 2.1 were obtained.
Co-reporter:Jian Zhi, Depeng Song, Zhiwen Li, Xia Lei and Aiguo Hu
Chemical Communications 2011 vol. 47(Issue 38) pp:10707-10709
Publication Date(Web):05 Sep 2011
DOI:10.1039/C1CC14169D
Embedding Pd nanoparticles in carbon thin film-lined SBA-15 nanoreactors provides highly efficient catalysts for heterogeneous cross coupling reactions in aqueous media. No leaching or aggregation of Pd nanoparticles was found in these nanoreactors after reusing them several times. The carbon thin film lining of these nanoreactors was further confirmed with small molecular arene probing experiments.
Co-reporter:Pei Gong, Zhengyan Chen, Yingying Chen, Wei Wang, Xiaosong Wang and Aiguo Hu
Chemical Communications 2011 vol. 47(Issue 14) pp:4240-4242
Publication Date(Web):25 Feb 2011
DOI:10.1039/C0CC05746K
Miniemulsion polymerization with amphiphilic gadolinium(III) complexes as metallosurfactants was explored as a new technique for the synthesis of high relaxivity MRI contrast agents. Well-defined metallo-colloids with up to 240% enhancement in relaxivity over their small molecular counterparts were obtained.
Co-reporter:Yuli Xiao
Macromolecular Rapid Communications 2011 Volume 32( Issue 21) pp:1688-1698
Publication Date(Web):
DOI:10.1002/marc.201100378
Co-reporter:Jianguo Ma;Sheng Deng;Xin Cheng;Wei Wei
Journal of Polymer Science Part A: Polymer Chemistry 2011 Volume 49( Issue 18) pp:3951-3959
Publication Date(Web):
DOI:10.1002/pola.24834
Abstract
A method for covalent functionalization of multiwalled carbon nanotubes (MWCNTs) was developed using the free radicals generated through Bergman cyclization of enediyne-containing compounds. Four enediyne-bearing Frechet type dendrimers were synthesized in good quantities and characterized. Then, the enediyne-containing molecules were reacted with MWCNTs in N-methyl-2-pyrrolidinone at 206 °C under nitrogen. The structure and morphology of the resulting products were characterized by thermogravimetric analysis, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy. The dendrimer-functionalized MWCNTs showed good solubility/dispersibility in common organic solvents and polymer solutions. They were used in the formation of polymer composites through electrospinning with polycaprolactone. The results confirmed the surface functionalization of MWCNTs. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Co-reporter:Benchuan Zhu;Guannan Qian;Yuli Xiao;Sheng Deng;Meng Wang
Journal of Polymer Science Part A: Polymer Chemistry 2011 Volume 49( Issue 24) pp:5330-5338
Publication Date(Web):
DOI:10.1002/pola.25013
Abstract
Employing enediynes as crosslinking precursors, a novel yet efficient strategy, namely photo-triggered Bergman cyclization, was integrated with intramolecular chain collapse to yield polymeric nanoparticles with the size regime below 20 nm. Enediyne motif was designed delicately to possess a high photo-reactivity, with the double bond locked in a methyl benzoate ring while triple bonds substituted with phenyls. Single electron transfer-living radical polymerization was conducted to provide linear acrylate copolymers with controlled molecular weights and narrow polydispersities. Poly(butylarylate-co-5) went through UV-irradiation with a concurrent Bergman cyclization, resulting in well-defined ultrafine polymeric nanoparticles. Results from NMR, Raman scattering, photoluminescence and UV-vis spectra corroborated the presence of conjugative structures in the polymeric nanoparticles, indicating the occurrence of photo-induced Bergman cyclization. A series of other acrylate-based nanoparticles were investigated to confirm the applicability of such a unique strategy in thermal sensitive but UV-stable polymeric structures, making photo-Bergman cyclization a promising tool towards polymeric nanoparticles. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Co-reporter:Jianguo Ma;Xiaowei Ma;Sheng Deng;Fei Li
Journal of Polymer Science Part A: Polymer Chemistry 2011 Volume 49( Issue 6) pp:1368-1375
Publication Date(Web):
DOI:10.1002/pola.24556
Abstract
In this article, dendronized polymers with rigid backbones were synthesized from enediyne-containing Frechet-type dendrimers. Two generations of dendrimers were conically incorporated with 3-(2-(2-(trimethylsilyl)ethynyl)phenyl)prop-2-yn-1-ol. The trimethylsilyl protection groups of enediyne units were subsequently removed, and two types of brush polymers with rigid conjugated backbone were prepared through Bergman cyclization polymerization at elevated temperature under vacuum. The dendronized polymers were characterized with GPC, IR, UV–vis, and NMR spectroscopy. Furthermore, the morphology of the dendronized polymer was revealed by atomic force microscopy. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Co-reporter:Zhiwen Li, Depeng Song, Jian Zhi, and Aiguo Hu
The Journal of Physical Chemistry C 2011 Volume 115(Issue 32) pp:15829-15833
Publication Date(Web):July 18, 2011
DOI:10.1021/jp203393v
A template approach was demonstrated to prepare ultrathin ordered porous carbon through Bergman cyclization of enediyne self-assembled monolayers on silica nanoparticles, followed by carbonization and template removal. The sizes of macropores can be finely tuned by adjusting the sizes of silica nanoparticles. The structures of the carbonous products were characterized with scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption isotherm, and Raman spectroscopy. The results showed that these materials consisted of interconnected ordered macropores with ultrathin walls. Large BET surface areas (up to1786 m2/g), large pore volumes (∼1.24 cm3/g), and partially graphitized frameworks were revealed for these materials. Depending on these excellent properties, potential applications would be expected.
Co-reporter:Xi Yang, Zhiwen Li, Jian Zhi, Jianguo Ma and Aiguo Hu
Langmuir 2010 Volume 26(Issue 13) pp:11244-11248
Publication Date(Web):April 29, 2010
DOI:10.1021/la1005727
In this work, a bottom-up synthesis of ultrathin mesoporous carbon was developed through Bergman cyclization of enediyne containing compounds immobilized inside of SBA-15 nanochannels and followed by pyrolysis. Raman spectroscopy confirmed the occurrence of thermal Bergman cyclization inside the channels. Further heating under elevated temperature produced nanotube arrays in good yield. TEM images revealed the formation of interconnected tubular carbon due to the microtunnels of template. Raman spectra showed moderate degree of graphitization. Formation of enediyne SAMs on a template followed by the processing sequence developed in this work is promising to construct carbon materials with various nanoscopic morphology, such as carbon nanotube, graphene, and giant fullerene.
Co-reporter:Xin Cheng, Jianguo Ma, Jian Zhi, Xi Yang and Aiguo Hu
Macromolecules 2010 Volume 43(Issue 2) pp:909-913
Publication Date(Web):December 9, 2009
DOI:10.1021/ma902176j
This work reports synthesis of “rod−coil” brush polymers with rigid conjugated backbone. “Grafting through” strategy was employed via combination of ring-opening polymerization (ROP) and Bergman cyclization polymerization. Enediyne-containing macromonomers were first synthesized through ROP of caprolactone with dual-functional initiators conceiving free hydroxy groups and dialkynylbenzene moieties. After protection of terminal free hydroxy group of PCL chain and removal of trimethylsilyl protecting group of enediyne unit, the macromonomers were subjected to thermal Bergman cyclization under vacuum. The brush polymers obtained were characterized with GPC and NMR, IR, and UV−vis spectroscopy. The conjugated backbones were revealed as copolymers of naphthalene and indenylmethylene according to NMR analysis.
Co-reporter:Changcheng Miao;Jian Zhi;Shiyuan Sun;Xi Yang
Journal of Polymer Science Part A: Polymer Chemistry 2010 Volume 48( Issue 10) pp:2187-2193
Publication Date(Web):
DOI:10.1002/pola.23988
Abstract
A series of enediyne containing chiral phthalimides were synthesized through Sonogashira coupling reactions. These enediynes were then subjected to thermal Bergman cyclization under vacuum. Polynaphthalenes with pendant chiral groups were obtained and characterized using GPC, IR spectroscopy, NMR spectroscopy, UV–Vis spectroscopy, and photoluminescence analysis. Under properly optimized conditions, the chirality of chiral directing group was maintained according to CD spectra of final products. After removal of chiral directing groups, weak CD signals representative of main chain chirality were visible. Further modification of the structure of the enediyne compounds will facilitate the synthesis of chiral polynaphthalene through this rather simple way. Extension of the Bergman cyclization to polymer chemistry is promising in the construction of novel polymers with rigid polyarene backbones. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2187–2193, 2010
Co-reporter:Jianguo Ma;Xin Cheng;Xiaowei Ma;Sheng Deng
Journal of Polymer Science Part A: Polymer Chemistry 2010 Volume 48( Issue 23) pp:5541-5548
Publication Date(Web):
DOI:10.1002/pola.24365
Abstract
In this work, pristine multiwalled carbon nanotubes (MWNTs) were functionalized by utilizing the free radicals generated through Bergman cyclization of enediyne containing compounds 3. Polyesters were subsequently grafted from the surface of MWNTs through ring-opening polymerization of ε-caprolactone or lactide initiated by free hydroxy groups generated after hydrolysis of ester groups. Functionalized MWNTs were characterized with a variety of techniques, including TGA, NMR, IR, UV–vis, TEM, and Raman spectroscopy. After surface modification, MWNTs showed good solubility in common organic solvents and polymer solutions. Fabrication of MWNTs polymer nanocomposites was revealed through electrospinning with polycaprolactone. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Co-reporter:Youfu Wang, Rulin Xiong, Luhua Dong and Aiguo Hu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 15) pp:NaN5217-5217
Publication Date(Web):2014/01/21
DOI:10.1039/C3TA15311H
A bottom-up synthesis of three-dimensional (3D) carbon nanomembranes (CNMs) was developed through Friedel–Crafts cross-linking of phenyl self-assembled monolayers (SAMs) on silica nanospheres (SNSs) followed by high temperature treatment and template removal. The CNMs show a hierarchically 3D connected porous structure and the pore sizes are facilely tuned by varying the sizes of SNS templates. CNMs with high surface area (>1500 m2 g−1), large pore volume (∼3 cm3 g−1) and partially graphitized frameworks exhibited good performances as supercapacitor electrode materials. The specific capacitance of the porous 3D CNMs reached 202 F g−1 at a current density of 0.5 A g−1 in an aqueous electrolyte.
Co-reporter:Yingying Chen, Heng Yang, Weijun Tang, Xinhui Cui, Wei Wang, Xiangyu Chen, Yuan Yuan and Aiguo Hu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 40) pp:NaN5449-5449
Publication Date(Web):2013/08/07
DOI:10.1039/C3TB20807A
A new Gd(III)-based metallosurfactant with double quaternary-ammonium-containing long alkyl chains was developed and subjected to the miniemulsion polymerization of vinyl monomers, giving nanosized colloids (50–110 nm) with narrow size distribution. The size of the colloid particles can be easily tuned by adjusting the feeding ratio of metallosurfactant to monomer. SEM and XPS analysis showed that the Gd(III) complexes were attached on the surface of the colloids. ICP-AES analysis further quantified the contents of Gd(III) in the miniemulsions. T1 magnetic resonance imaging (MRI) showed that these Gd(III)-loading colloids exhibited relaxivity of up to 22.77 mM−1 s−1, much higher than that of Ominiscan® (4.64 mM−1 s−1).
Co-reporter:Benchuan Zhu, Shiyuan Sun, Youfu Wang, Sheng Deng, Guannan Qian, Meng Wang and Aiguo Hu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 3) pp:NaN586-586
Publication Date(Web):2012/11/06
DOI:10.1039/C2TC00140C
Even after several years of research, controlled synthesis of photoluminescent carbon nanodots (C-dots) still constitutes a major challenge, and investigation of their photoluminescence (PL) mechanism remains elusive. Various top-down and bottom-up approaches have been reported lately. However, these methods usually suffer from limited control over the major factors that dictate the PL behaviour of these fascinating carbon materials. To this end, we discover a new approach to prepare C-dots from size-tunable single chain polymeric nanoparticles. Taking advantage of the state of the art living radical polymerization technique and unique features of Bergman cyclization, narrowly dispersed C-dots are prepared in a straightforward manner. PL study shows that the optimal emission wavelength of C-dots red-shifts when the size of C-dots decreases, which is different from the trends typically found in semiconductor quantum dots and C-dots prepared from graphitized materials. To clarify the PL mechanism of C-dots prepared from different sources, a theoretical study based on density functional theory is performed. Two series of model compounds, fused aromatic rings and cyclo-1,4-naphthylenes, are chosen for C-dots with different microstructures. The calculation data indicate that PL energy of C-dots is dictated by the size and microstructure of the sp2 carbon core. For a C-dot with a graphitized core, the smaller the size of the core, the higher the PL energy, while for a C-dot with an amorphous core, an inverse trend is revealed. Surface reduction experiments further show that the quantum yield of C-dots is controlled by the surface chemistry.
Co-reporter:Jian Zhi, Sheng Deng, Yuxuan Zhang, Youfu Wang and Aiguo Hu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 9) pp:NaN3176-3176
Publication Date(Web):2013/01/07
DOI:10.1039/C2TA01253G
A three dimensional porous carbon nanomembrane (CNM), silica-supported CNM (SS-CNM), is developed by formation of a self-assembled monolayer of an enediyne compound on the surface of mesoporous silica (SBA-15) followed by Bergman cyclization and carbonization. The SS-CNM is applied as a conductive support for the electroactive material Co3O4 to fabricate advanced supercapacitors. A large fraction of Co3O4 clusters (66% of total weight) are impregnated in the SS-CNM host to form regularly packed nanorods with diameters of 7 nm. The specific capacitance of the supercapacitor electrode material reaches 1086 F g−1 (1645 F g−1 based on Co3O4) with aqueous electrolyte. This extraordinary high performance of the electrode material is attributed to the unique pore structure of the SS-CNM support that enhances the use of active material and shortens the transport path of ions and electrons.
Co-reporter:Luhua Dong, Zhiwei Zheng, Youfu Wang, Xing Li, Jianli Hua and Aiguo Hu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 21) pp:NaN11614-11614
Publication Date(Web):2015/04/21
DOI:10.1039/C5TA01861G
The co-sensitization of N719 with conjugated polyphenylenes for dye-sensitized solar cells (DSSCs) was demonstrated. The conjugated polyphenylenes (6-BC and 7-BC), which contain two triphenylamine (TPA) groups as electron donors and carboxylic acids as adsorption groups, were prepared from thermally triggered Bergman cyclization polymerization of two maleimide-based enediynes, 6 and 7. Both the short-circuit photocurrent density (JSC) and the open-circuit voltage (VOC) of the co-sensitized DSSCs were enhanced due to the increase in light harvesting and the retardation of electron recombination and dye aggregation when N719 was co-sensitized with the conjugated polyphenylenes. The co-sensitized (7-BC + N719) DSSC showed a high efficiency of 9.68% (VOC of 750 mV, JSC of 18.18 mA cm−2 and FF of 0.71), exhibiting an improvement of 16% compared to the devices sensitized with N719 (PCE of 8.34%) alone under identical conditions.
Co-reporter:Benchuan Zhu, Jianguo Ma, Zhiwen Li, Jing Hou, Xin Cheng, Guannan Qian, Pai Liu and Aiguo Hu
Journal of Materials Chemistry A 2011 - vol. 21(Issue 8) pp:NaN2683-2683
Publication Date(Web):2011/01/12
DOI:10.1039/C0JM03143G
Polymeric nanoparticles were synthesized through Bergman cyclization mediated intramolecular chain collapse. Enediyne moieties were incorporated into linear polymers through copolymerization or post-polymerization modification. The resulted enediyne containing copolymers were then subjected to intramolecular chain collapse under ultra-dilute condition or applying a continuous addition technique. The occurrence of Bergman cyclization was confirmed with IR, NMR and DSC analysis. The intramolecular chain collapse was characterized with GPC, DSC, and AFM. Dramatic decreases of apparent molecular weights of linear copolymers were observed after Bergman cyclization. The structural diversity of enediyne precursors and mild chain collapse condition allow wide monomer selection, which facilitates preparation of a broad range of polymeric nanoparticles. Low-k dielectric thin films were prepared using polymeric nanoparticles through “porogen” approach. The packing tightness of polymeric nanoparticles showed strong influence on film formation behavior with MSSQ matrix. With tightly packed polymeric nanoparticles as sacrificial pore generators, thin films with dielectric constants of as low as 2.1 were obtained.
Co-reporter:Youfu Wang, Luhua Dong, Rulin Xiong and Aiguo Hu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 46) pp:NaN7735-7735
Publication Date(Web):2013/08/30
DOI:10.1039/C3TC30949E
As emergent nanolights for bioimaging, catalysis, sensors, and photoelectronics, carbon dots (C-dots) have attracted much research attention. However, the practical and scalable preparation of C-dots has been less explored, even after various top-down and bottom-up approaches being reported recently. To this end, we discover a new approach to prepare C-dots by simply unzipping core–shell polymeric nanoparticles, prepared by a microemulsion polymerization. Uniformly distributed N-doped C-dots are prepared by the pyrolysis of PAN@PMMA core–shell nanoparticles at different temperatures, followed by dialysis. TEM analysis shows that many of the C-dots of 2–3 nm size are unzipped from each polymeric particle. All the purified C-dots show a bandgap-like photoluminescence (PL) behaviour, with dual emission and a stable PL between pH 5–12.
Co-reporter:Youfu Wang and Aiguo Hu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 34) pp:NaN6939-6939
Publication Date(Web):2014/06/17
DOI:10.1039/C4TC00988F
Carbon quantum dots (CQDs, C-dots or CDs), which are generally small carbon nanoparticles (less than 10 nm in size) with various unique properties, have found wide use in more and more fields during the last few years. In this feature article, we describe the recent progress in the field of CQDs, focusing on their synthetic methods, size control, modification strategies, photoelectric properties, luminescent mechanism, and applications in biomedicine, optronics, catalysis and sensor issues.
Co-reporter:Jian Zhi, Depeng Song, Zhiwen Li, Xia Lei and Aiguo Hu
Chemical Communications 2011 - vol. 47(Issue 38) pp:NaN10709-10709
Publication Date(Web):2011/09/05
DOI:10.1039/C1CC14169D
Embedding Pd nanoparticles in carbon thin film-lined SBA-15 nanoreactors provides highly efficient catalysts for heterogeneous cross coupling reactions in aqueous media. No leaching or aggregation of Pd nanoparticles was found in these nanoreactors after reusing them several times. The carbon thin film lining of these nanoreactors was further confirmed with small molecular arene probing experiments.
Co-reporter:Qin Zhu, Heng Yang, Yuanyuan Li, Yu Tian, Wei Wang, Weijun Tang, Yuan Yuan and Aiguo Hu
Journal of Materials Chemistry A 2016 - vol. 4(Issue 45) pp:NaN7248-7248
Publication Date(Web):2016/10/12
DOI:10.1039/C6TB01998F
HP-DO3A-based cationic amphiphilic Gd(III) complexes bearing quaternary ammonium salts of different alkyl chain lengths were synthesized. The structures of the intermediates, the ligands and the Gd(III) complexes were characterized by 1H NMR, 13C NMR, ESI and MALDI-TOF mass spectrometry. Relaxation studies of the amphiphilic Gd(III) complexes revealed that long alkyl chains facilitated the formation of micelles in an aqueous solution and afforded high relaxivity. Electrostatic self-assembly of the GdL1 complex with polyacrylate sodium (PAAS) showed significant relaxation enhancement with the relaxivity being up to 20.03 mM−1 s−1 at 1.5 T, which was about 4 times that of the commercial MRI contrast agent, Gd-DTPA. The long hydrophobic chain was found to play an important role in the formation of the self-assembly. Zeta potential and dynamic light scattering measurements were carried out to reveal the aggregation process during the assembly. Good biocompatibility of the complexes and high cell viability were found in HepG-2 and L-02 cells by the MTT assay. The reactive oxygen species (ROS) generation study further confirmed the biocompatibility. In vivo imaging showed significant contrast enhancement in the liver and bladder regions.
Co-reporter:Liang Dong, Qiang Sun, Chi Zhang, Zhiwen Li, Kai Sheng, Huihui Kong, Qinggang Tan, Yunxiang Pan, Aiguo Hu and Wei Xu
Chemical Communications 2013 - vol. 49(Issue 17) pp:NaN1737-1737
Publication Date(Web):2013/01/11
DOI:10.1039/C3CC38383K
The native copper adatoms get trapped in a self-assembled molecular nanostructure which is mainly formed by the intermolecular van der Waals interactions, and two dominating specific binding modes between the adatoms and the molecules are revealed at the atomic scale by high-resolution STM imaging.
Co-reporter:Qinggang Tan, Chi Zhang, Ning Wang, Xiujuan Zhu, Qiang Sun, Mikkel F. Jacobsen, Kurt V. Gothelf, Flemming Besenbacher, Aiguo Hu and Wei Xu
Chemical Communications 2014 - vol. 50(Issue 3) pp:NaN358-358
Publication Date(Web):2013/10/28
DOI:10.1039/C3CC46149A
From an interplay of high-resolution scanning tunneling microscopy (STM) imaging and density functional theory (DFT) calculations we demonstrate that by delicately choosing the parent molecule (adenine) we are able to tune the self-assembled nanostructures of adenine derivatives which are directed by the specific intermolecular interactions provided by the adenine moiety.
Co-reporter:Depeng Song, Yu Tian, Shuai Huang, Baojun Li, Yuan Yuan and Aiguo Hu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 43) pp:NaN8588-8588
Publication Date(Web):2015/09/21
DOI:10.1039/C5TB01867F
An acyclic enediyne with a furyl tethering group and two pH-sensitive orthoester groups at the alkynyl termini was synthesized. The enediyne compound yielded free radicals, which can be further trapped by other atoms, under acidic conditions at ambient temperature. It exhibited high cytotoxicity towards tumor cells, and affected normal cells much less, while showing very low cytotoxicity to both types of cells once the furan group was reacted with a dienophile, 4-phenyl-1,2,4-triazoline-3,5-dione. Confocal laser scanning microscopy experiments showed that the derivation of the furan group dictated the cytosis of the enediyne molecules. The cytotoxicity of the enediyne molecules disappeared when cytosis was hindered. The introduction of a furyl tethering group into enediyne represents a new design strategy of “intelligent” antitumor antibiotics that can distinguish tumor and normal cells.
Co-reporter:Depeng Song, Shiyuan Sun, Yu Tian, Shuai Huang, Yun Ding, Yuan Yuan and Aiguo Hu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 16) pp:NaN3200-3200
Publication Date(Web):2015/02/17
DOI:10.1039/C4TB02018A
A pH-sensitive acyclic enediyne (1) was synthesized for efficient DNA-cleavage and tumor cell suppression. Unlike other acyclic enediynes, this novel enediyne transforms into a highly reactive enediyne (2) in an acidic environment only, which undergoes Bergman cyclization spontaneously at ambient temperature. An EPR study on the enediyne 2 confirmed the generation of free radicals through Bergman cyclization. The activated enediyne induced DNA-cleavage and exhibited cytotoxicity towards various tumor cells under the action of diradicals arising from spontaneous Bergman cyclization at physiological temperature. These findings suggest a novel strategy of anticancer drug design, where the activation of the silent compound takes place under the acidic environment inside the tumor cells.
Co-reporter:Pei Gong, Zhengyan Chen, Yingying Chen, Wei Wang, Xiaosong Wang and Aiguo Hu
Chemical Communications 2011 - vol. 47(Issue 14) pp:NaN4242-4242
Publication Date(Web):2011/02/25
DOI:10.1039/C0CC05746K
Miniemulsion polymerization with amphiphilic gadolinium(III) complexes as metallosurfactants was explored as a new technique for the synthesis of high relaxivity MRI contrast agents. Well-defined metallo-colloids with up to 240% enhancement in relaxivity over their small molecular counterparts were obtained.