Co-reporter:Chunbai He, Kuangda Lu, and Wenbin Lin
Journal of the American Chemical Society September 3, 2014 Volume 136(Issue 35) pp:12253-12256
Publication Date(Web):August 19, 2014
DOI:10.1021/ja507333c
Real-time measurement of intracellular pH in live cells is of great importance for understanding physiological/pathological processes and developing intracellular drug delivery systems. We report here the first use of nanoscale metal–organic frameworks (NMOFs) for intracellular pH sensing in live cells. Fluorescein isothiocyanate (FITC) was covalently conjugated to a UiO NMOF to afford F-UiO NMOFs with exceptionally high FITC loadings, efficient fluorescence, and excellent ratiometric pH-sensing properties. Upon rapid and efficient endocytosis, F-UiO remained structurally intact inside endosomes. Live cell imaging studies revealed endo- and exocytosis of F-UiO and endosome acidification in real time. Fluorescently labeled NMOFs thus represent a new class of nanosensors for intracellular pH sensing and provide an excellent tool for studying NMOF–cell interactions.
Co-reporter:Pengfei Ji, Xuanyu Feng, Samuel S. Veroneau, Yang Song, and Wenbin Lin
Journal of the American Chemical Society November 8, 2017 Volume 139(Issue 44) pp:15600-15600
Publication Date(Web):October 17, 2017
DOI:10.1021/jacs.7b09093
We report the quantitative conversion of [MIV6(μ3-O)4(μ3-OH)4Cl12]6– nodes in the MCl2-BTC metal–organic framework into the [MIII6(μ3-O)4(μ3-ONa)4H6]6– nodes in MIIIH-BTC (M = Zr, Hf; BTC is 1,3,5-benzenetricarboxylate) via bimetallic reductive elimination of H2 from putative [MIV6(μ3-O)4(μ3-OH)4H12]6– nodes. The coordinatively unsaturated MIIIH centers in MIIIH-BTC are highly active and selective for 1,4-dearomative hydroboration and hydrosilylation of pyridines and quinolines. This work demonstrated the potential of secondary building unit transformation in generating electronically unique and homogeneously inaccessible single-site solid catalysts for organic synthesis.
Co-reporter:Pengfei Ji, Kuntal Manna, Zekai Lin, Xuanyu Feng, Ania Urban, Yang Song, and Wenbin Lin
Journal of the American Chemical Society May 24, 2017 Volume 139(Issue 20) pp:7004-7004
Publication Date(Web):May 6, 2017
DOI:10.1021/jacs.7b02394
We report here the synthesis of a robust and porous metal–organic framework (MOF), Zr12-TPDC, constructed from triphenyldicarboxylic acid (H2TPDC) and an unprecedented Zr12 secondary building unit (SBU): Zr12(μ3-O)8(μ3-OH)8(μ2-OH)6. The Zr12-SBU can be viewed as an inorganic node dimerized from two commonly observed Zr6 clusters via six μ2-OH groups. The metalation of Zr12-TPDC SBUs with CoCl2 followed by treatment with NaBEt3H afforded a highly active and reusable solid Zr12-TPDC-Co catalyst for the hydrogenation of nitroarenes, nitriles, and isocyanides to corresponding amines with excellent activity and selectivity. This work highlights the opportunity in designing novel MOF-supported single-site solid catalysts by tuning the electronic and steric properties of the SBUs.
Co-reporter:Ruihan Dai, Fei Peng, Pengfei Ji, Kuangda Lu, Cheng Wang, Junliang Sun, and Wenbin Lin
Inorganic Chemistry July 17, 2017 Volume 56(Issue 14) pp:8128-8128
Publication Date(Web):June 22, 2017
DOI:10.1021/acs.inorgchem.7b00845
Nanoscale metal–organic frameworks (nMOFs) have shown tremendous potential in cancer therapy and biomedical imaging. However, their small dimensions present a significant challenge in structure determination by single-crystal X-ray crystallography. We report here the structural determination of nMOFs by rotation electron diffraction (RED). Two isostructural Zr- and Hf-based nMOFs with linear biphenyldicarboxylate (BPDC) or bipyridinedicarboxylate (BPYDC) linkers are stable under intense electron beams to allow the collection of high-quality RED data, which reveal a MOF structure with M12(μ3-O)8(μ3-OH)8(μ2-OH)6 (M = Zr, Hf) secondary building units (SBUs). The nMOF structures differ significantly from their UiO bulk counterparts with M6(μ3-O)4(μ3-OH)4 SBUs and provide the foundation for clarifying the structures of a series of previously reported nMOFs with significant potential in cancer therapy and biological imaging. Our work clearly demonstrates the power of RED in determining nMOF structures and elucidating the formation mechanism of distinct nMOF morphologies.
Co-reporter:Pengfei Ji, Joseph B. Solomon, Zekai Lin, Alison Johnson, Richard F. Jordan, and Wenbin Lin
Journal of the American Chemical Society August 23, 2017 Volume 139(Issue 33) pp:11325-11325
Publication Date(Web):August 11, 2017
DOI:10.1021/jacs.7b05761
We report the stepwise and quantitative transformation of the Zr6(μ3-O)4(μ3-OH)4(HCO2)6 nodes in Zr-BTC (MOF-808) to the [Zr6(μ3-O)4(μ3-OH)4Cl12]6– nodes in ZrCl2-BTC, and then to the organometallic [Zr6(μ3-O)4(μ3-OLi)4R12]6– nodes in ZrR2-BTC (R = CH2SiMe3 or Me). Activation of ZrCl2-BTC with MMAO-12 generates ZrMe-BTC, which is an efficient catalyst for ethylene polymerization. ZrMe-BTC displays unusual electronic and steric properties compared to homogeneous Zr catalysts, possesses multimetallic active sites, and produces high-molecular-weight linear polyethylene. Metal–organic framework nodes can thus be directly transformed into novel single-site solid organometallic catalysts without homogeneous analogs for polymerization reactions.
Co-reporter:Xin-Bao Han, Zhi-Ming Zhang, Teng Zhang, Yang-Guang Li, Wenbin Lin, Wansheng You, Zhong-Min Su, and En-Bo Wang
Journal of the American Chemical Society April 9, 2014 Volume 136(Issue 14) pp:5359-5366
Publication Date(Web):March 24, 2014
DOI:10.1021/ja412886e
A series of all-inorganic, abundant-metal-based, high-nuclearity cobalt–phosphate (Co–Pi) molecular catalysts [{Co4(OH)3(PO4)}4(SiW9O34)4]32– (1), [{Co4(OH)3(PO4)}4(GeW9O34)4]32– (2), [{Co4(OH)3(PO4)}4(PW9O34)4]28– (3), and [{Co4(OH)3(PO4)}4(AsW9O34)4]28– (4) were synthesized and shown to be highly effective at photocatalytic water oxidation. The {Co16(PO4)4} cluster contains a Co4O4 cubane which is structurally analogous to the [Mn3CaO4] core of the oxygen-evolving complex (OEC) in photosystem II (PSII). Compounds 1–4 were shown to be the first POM-based Co–Pi-cluster molecular catalysts for visible light-driven water oxidation, thus serving as a functional model of the OEC in PSII. The systematic synthesis of four isostructural analogues allowed for investigating the influence of different heteroatoms in the POM ligands on the photocatalytic activities of these Co–Pi cluster WOCs. Further, the POM-based photocatalysts readily recrystallized from the photocatalytic reaction systems with the polyoxoanion structures unchanged, which together with the laser flash photolysis, dynamic light-scattering, 31P NMR, UV–vis absorption, POM extraction, and ICP-MS analysis results collectively confirmed that compounds 1–4 maintain their structural integrity under the photocatalytic conditions. This study provides not only a valuable molecular model of the “Co–Pi” catalysts with a well-defined structure but also an unprecedented opportunity to fine-tune high-nuclearity POM clusters for visible light-driven water splitting.
Co-reporter:Go Oshima, Nining Guo, Chunbai He, Melinda E. Stack, ... Ralph R. Weichselbaum
Molecular Therapy 2017 Volume 25, Issue 7(Volume 25, Issue 7) pp:
Publication Date(Web):5 July 2017
DOI:10.1016/j.ymthe.2017.04.005
Multiple therapeutic agents are typically used in concert to effectively control metastatic tumors. Recently, we described microRNAs that are associated with the oligometastatic state, in which a limited number of metastatic tumors progress to more favorable outcomes. Here, we report the effective delivery of an oligometastatic microRNA (miR-655-3p) to colorectal liver metastases using nanoscale coordination polymers (NCPs). The NCPs demonstrated a targeted and prolonged distribution of microRNAs to metastatic liver tumors. Tumor-targeted microRNA miR-655-3p suppressed tumor growth when co-delivered with oxaliplatin, suggesting additive or synergistic interactions between microRNAs and platinum drugs. This is the first known example of systemically administered nanoparticles delivering an oligometastatic microRNA to advanced metastatic liver tumors and demonstrating tumor-suppressive effects. Our results suggest a potential therapeutic strategy for metastatic liver disease by the co-delivery of microRNAs and conventional cytotoxic agents using tumor-specific NCPs.Download high-res image (106KB)Download full-size image
Co-reporter:Nathan C. Thacker;Pengfei Ji;Zekai Lin;Ania Urban
Faraday Discussions 2017 (Volume 201) pp:303-315
Publication Date(Web):2017/09/06
DOI:10.1039/C7FD00030H
We report here the synthesis of a robust and highly porous Fe-phenanthroline-based metal–organic framework (MOF) and its application in catalyzing challenging inter- and intramolecular C–H amination reactions. For the intermolecular amination reactions, a FeBr2-metalated MOF selectively functionalized secondary benzylic and allylic C–H bonds. The intramolecular amination reactions utilizing organic azides as the nitrene source required the reduction of the FeBr2-metalated MOF with NaBHEt3 to generate the active catalyst. For both reactions, Fe or Zr leaching was less than 0.1%, and MOFs could be recycled and reused with no loss in catalytic activity. Furthermore, MOF catalysts were significantly more active than the corresponding homogeneous analogs. This work demonstrates the great potential of MOFs in generating highly active, recyclable, and reusable earth abundant metal catalysts for challenging organic transformations.
Co-reporter:Guangxu Lan;Kaiyuan Ni;Ruoyu Xu;Dr. Kuangda Lu;Zekai Lin;Christina Chan; Wenbin Lin
Angewandte Chemie International Edition 2017 Volume 56(Issue 40) pp:12102-12106
Publication Date(Web):2017/09/25
DOI:10.1002/anie.201704828
AbstractWe report the rational design of metal–organic layers (MOLs) that are built from [Hf6O4(OH)4(HCO2)6] secondary building units (SBUs) and Ir[bpy(ppy)2]+- or [Ru(bpy)3]2+-derived tricarboxylate ligands (Hf-BPY-Ir or Hf-BPY-Ru; bpy=2,2′-bipyridine, ppy=2-phenylpyridine) and their applications in X-ray-induced photodynamic therapy (X-PDT) of colon cancer. Heavy Hf atoms in the SBUs efficiently absorb X-rays and transfer energy to Ir[bpy(ppy)2]+ or [Ru(bpy)3]2+ moieties to induce PDT by generating reactive oxygen species (ROS). The ability of X-rays to penetrate deeply into tissue and efficient ROS diffusion through ultrathin 2D MOLs (ca. 1.2 nm) enable highly effective X-PDT to afford superb anticancer efficacy.
Co-reporter:Wenjie Shi;Lingyun Cao;Hua Zhang;Xin Zhou;Bing An;Zekai Lin;Ruihan Dai; Jianfeng Li; Cheng Wang; Wenbin Lin
Angewandte Chemie International Edition 2017 Volume 56(Issue 33) pp:9704-9709
Publication Date(Web):2017/08/07
DOI:10.1002/anie.201703675
AbstractMicroenvironments in enzymes play crucial roles in controlling the activities and selectivities of reaction centers. Herein we report the tuning of the catalytic microenvironments of metal–organic layers (MOLs), a two-dimensional version of metal–organic frameworks (MOFs) with thickness down to a monolayer, to control product selectivities. By modifying the secondary building units (SBUs) of MOLs with monocarboxylic acids, such as gluconic acid, we changed the hydrophobicity/hydrophilicity around the active sites and fine-tuned the selectivity in photocatalytic oxidation of tetrahydrofuran (THF) to exclusively afford butyrolactone (BTL), likely a result of prolonging the residence time of reaction intermediates in the hydrophilic microenvironment of catalytic centers. Our work highlights new opportunities in using functional MOLs as highly tunable and selective two-dimensional catalytic materials.
Co-reporter:Wenjie Shi;Lingyun Cao;Hua Zhang;Xin Zhou;Bing An;Zekai Lin;Ruihan Dai; Jianfeng Li; Cheng Wang; Wenbin Lin
Angewandte Chemie International Edition 2017 Volume 56(Issue 33) pp:
Publication Date(Web):2017/08/07
DOI:10.1002/anie.201783361
Biomimetic CatalysisC. Wang, W. Lin, et al. show in their Communication on page 9704 ff. that two-dimensional metal–organic layers (MOLs) with FeII catalytic centers mimic oxidase enzymes in the aerobic photo-oxidization of tetrahydrofuran.
Co-reporter:Wenjie Shi;Lingyun Cao;Hua Zhang;Xin Zhou;Bing An;Zekai Lin;Ruihan Dai; Jianfeng Li; Cheng Wang; Wenbin Lin
Angewandte Chemie 2017 Volume 129(Issue 33) pp:9836-9841
Publication Date(Web):2017/08/07
DOI:10.1002/ange.201703675
AbstractMicroenvironments in enzymes play crucial roles in controlling the activities and selectivities of reaction centers. Herein we report the tuning of the catalytic microenvironments of metal–organic layers (MOLs), a two-dimensional version of metal–organic frameworks (MOFs) with thickness down to a monolayer, to control product selectivities. By modifying the secondary building units (SBUs) of MOLs with monocarboxylic acids, such as gluconic acid, we changed the hydrophobicity/hydrophilicity around the active sites and fine-tuned the selectivity in photocatalytic oxidation of tetrahydrofuran (THF) to exclusively afford butyrolactone (BTL), likely a result of prolonging the residence time of reaction intermediates in the hydrophilic microenvironment of catalytic centers. Our work highlights new opportunities in using functional MOLs as highly tunable and selective two-dimensional catalytic materials.
Co-reporter:Wenjie Shi;Lingyun Cao;Hua Zhang;Xin Zhou;Bing An;Zekai Lin;Ruihan Dai; Jianfeng Li; Cheng Wang; Wenbin Lin
Angewandte Chemie 2017 Volume 129(Issue 33) pp:
Publication Date(Web):2017/08/07
DOI:10.1002/ange.201783361
Biomimetische KatalyseC. Wang, W. Lin et al. beschreiben in ihrer Zuschrift auf S. 9836 zweidimensionale Metall-organische Schichten mit katalytischen FeII-Zentren, die Oxidase-Enzyme bei der aeroben Photooxidation von Tetrahydrofuran nachahmen.
Co-reporter:Guangxu Lan;Kaiyuan Ni;Ruoyu Xu;Dr. Kuangda Lu;Zekai Lin;Christina Chan; Wenbin Lin
Angewandte Chemie 2017 Volume 129(Issue 40) pp:12270-12274
Publication Date(Web):2017/09/25
DOI:10.1002/ange.201704828
AbstractWe report the rational design of metal–organic layers (MOLs) that are built from [Hf6O4(OH)4(HCO2)6] secondary building units (SBUs) and Ir[bpy(ppy)2]+- or [Ru(bpy)3]2+-derived tricarboxylate ligands (Hf-BPY-Ir or Hf-BPY-Ru; bpy=2,2′-bipyridine, ppy=2-phenylpyridine) and their applications in X-ray-induced photodynamic therapy (X-PDT) of colon cancer. Heavy Hf atoms in the SBUs efficiently absorb X-rays and transfer energy to Ir[bpy(ppy)2]+ or [Ru(bpy)3]2+ moieties to induce PDT by generating reactive oxygen species (ROS). The ability of X-rays to penetrate deeply into tissue and efficient ROS diffusion through ultrathin 2D MOLs (ca. 1.2 nm) enable highly effective X-PDT to afford superb anticancer efficacy.
Co-reporter:C. W. Abney, R. T. Mayes, M. Piechowicz, Z. Lin, V. S. Bryantsev, G. M. Veith, S. Dai and W. Lin
Energy & Environmental Science 2016 vol. 9(Issue 2) pp:448-453
Publication Date(Web):12 Nov 2015
DOI:10.1039/C5EE02913A
Limited resource availability and population growth have motivated interest in harvesting valuable metals from unconventional reserves, but developing selective adsorbents for this task requires structural knowledge of metal binding environments. Amidoxime polymers have been identified as the most promising platform for large-scale extraction of uranium from seawater. However, despite more than 30 years of research, the uranyl coordination environment on these adsorbents has not been positively identified. We report the first XAFS investigation of polyamidoxime-bound uranyl, with EXAFS fits suggesting a cooperative chelating model, rather than the tridentate or η2 motifs proposed by small molecule and computational studies. Samples exposed to environmental seawater also display a feature consistent with a μ2-oxo-bridged transition metal in the uranyl coordination sphere, suggesting in situ formation of a specific binding site or mineralization of uranium on the polymer surface. These unexpected findings challenge several long-held assumptions and have significant implications for development of polymer adsorbents with high selectivity.
Co-reporter:Takahiro Sawano, Zekai Lin, Dean Boures, Bing An, Cheng Wang, and Wenbin Lin
Journal of the American Chemical Society 2016 Volume 138(Issue 31) pp:9783-9786
Publication Date(Web):July 25, 2016
DOI:10.1021/jacs.6b06239
Mono(phosphine)–M (M–PR3; M = Rh and Ir) complexes selectively prepared by postsynthetic metalation of a porous triarylphosphine-based metal–organic framework (MOF) exhibited excellent activity in the hydrosilylation of ketones and alkenes, the hydrogenation of alkenes, and the C–H borylation of arenes. The recyclable and reusable MOF catalysts significantly outperformed their homogeneous counterparts, presumably via stabilizing M–PR3 intermediates by preventing deleterious disproportionation reactions/ligand exchanges in the catalytic cycles.
Co-reporter:Pengfei Ji, Kuntal Manna, Zekai Lin, Ania Urban, Francis X. Greene, Guangxu Lan, and Wenbin Lin
Journal of the American Chemical Society 2016 Volume 138(Issue 37) pp:12234-12242
Publication Date(Web):September 6, 2016
DOI:10.1021/jacs.6b06759
We report here the synthesis of robust and porous metal–organic frameworks (MOFs), M-MTBC (M = Zr or Hf), constructed from the tetrahedral linker methane-tetrakis(p-biphenylcarboxylate) (MTBC) and two types of secondary building units (SBUs): cubic M8(μ2-O)8(μ2-OH)4 and octahedral M6(μ3-O)4(μ3-OH)4. While the M6-SBU is isostructural with the 12-connected octahedral SBUs of UiO-type MOFs, the M8-SBU is composed of eight MIV ions in a cubic fashion linked by eight μ2-oxo and four μ2-OH groups. The metalation of Zr-MTBC SBUs with CoCl2, followed by treatment with NaBEt3H, afforded highly active and reusable solid Zr-MTBC-CoH catalysts for the hydrogenation of alkenes, imines, carbonyls, and heterocycles. Zr-MTBC-CoH was impressively tolerant of a range of functional groups and displayed high activity in the hydrogenation of tri- and tetra-substituted alkenes with TON > 8000 for the hydrogenation of 2,3-dimethyl-2-butene. Our structural and spectroscopic studies show that site isolation of and open environments around the cobalt-hydride catalytic species at Zr8-SBUs are responsible for high catalytic activity in the hydrogenation of a wide range of challenging substrates. MOFs thus provide a novel platform for discovering and studying new single-site base-metal solid catalysts with enormous potential for sustainable chemical synthesis.
Co-reporter:Pengfei Ji, Takahiro Sawano, Zekai Lin, Ania Urban, Dean Boures, and Wenbin Lin
Journal of the American Chemical Society 2016 Volume 138(Issue 45) pp:14860-14863
Publication Date(Web):October 28, 2016
DOI:10.1021/jacs.6b10055
We report the stepwise, quantitative transformation of CeIV6(μ3-O)4(μ3-OH)4(OH)6(OH2)6 nodes in a new Ce-BTC (BTC = trimesic acid) metal–organic framework (MOF) into the first CeIII6(μ3-O)4(μ3-OLi)4(H)6(THF)6Li6 metal-hydride nodes that effectively catalyze hydroboration and hydrophosphination reactions. CeH-BTC displays low steric hindrance and electron density compared to homogeneous organolanthanide catalysts, which likely accounts for the unique 1,4-regioselectivity for the hydroboration of pyridine derivatives. MOF nodes can thus be directly transformed into novel single-site solid catalysts without homogeneous counterparts for sustainable chemical synthesis.
Co-reporter:Xiaopin Duan, Christina Chan, Nining Guo, Wenbo Han, Ralph R. Weichselbaum, and Wenbin Lin
Journal of the American Chemical Society 2016 Volume 138(Issue 51) pp:16686-16695
Publication Date(Web):December 2, 2016
DOI:10.1021/jacs.6b09538
An effective, nontoxic, tumor-specific immunotherapy is the ultimate goal in the battle against cancer, especially the metastatic disease. Checkpoint blockade-based immunotherapies have been shown to be extraordinarily effective but benefit only the minority of patients whose tumors have been pre-infiltrated by T cells. Here, we show that Zn-pyrophosphate (ZnP) nanoparticles loaded with the photosensitizer pyrolipid (ZnP@pyro) can kill tumor cells upon irradiation with light directly by inducing apoptosis and/or necrosis and indirectly by disrupting tumor vasculature and increasing tumor immunogenicity. Furthermore, immunogenic ZnP@pyro photodynamic therapy (PDT) treatment sensitizes tumors to checkpoint inhibition mediated by a PD-L1 antibody, not only eradicating the primary 4T1 breast tumor but also significantly preventing metastasis to the lung. The abscopal effects on both 4T1 and TUBO bilateral syngeneic mouse models further demonstrate that ZnP@pyro PDT treatment combined with anti-PD-L1 results in the eradication of light-irradiated primary tumors and the complete inhibition of untreated distant tumors by generating a systemic tumor-specific cytotoxic T cell response. These findings indicate that nanoparticle-mediated PDT can potentiate the systemic efficacy of checkpoint blockade immunotherapies by activating the innate and adaptive immune systems in tumor microenvironment.
Co-reporter:Kuangda Lu, Chunbai He, Nining Guo, Christina Chan, Kaiyuan Ni, Ralph R. Weichselbaum, and Wenbin Lin
Journal of the American Chemical Society 2016 Volume 138(Issue 38) pp:12502-12510
Publication Date(Web):August 30, 2016
DOI:10.1021/jacs.6b06663
Photodynamic therapy (PDT) can destroy local tumors and minimize normal tissue damage, but is ineffective at eliminating metastases. Checkpoint blockade immunotherapy has enjoyed recent success in the clinic, but only elicits limited rates of systemic antitumor response for most cancers due to insufficient activation of the host immune system. Here we describe a treatment strategy that combines PDT by a new chlorin-based nanoscale metal–organic framework (nMOF), TBC-Hf, and a small-molecule immunotherapy agent that inhibits indoleamine 2,3-dioxygenase (IDO), encapsulated in the nMOF channels to induce systemic antitumor immunity. The synergistic combination therapy achieved effective local and distant tumor rejection in colorectal cancer models. We detected increased T cell infiltration in the tumor microenvironment after activation of the immune system with the combination of IDO inhibition by the small-molecule immunotherapy agent and immunogenic cell death induced by PDT. We also elucidated the underlying immunological mechanisms and revealed compensatory roles of neutrophils and B cells in presenting tumor-associated antigens to T cells in this combination therapy. We believe that nMOF-enabled PDT has the potential to significantly enhance checkpoint blockade cancer immunotherapy, affording clinical benefits for the treatment of many difficult-to-treat cancers.
Co-reporter:Nathan C. Thacker; Zekai Lin; Teng Zhang; James C. Gilhula; Carter W. Abney
Journal of the American Chemical Society 2016 Volume 138(Issue 10) pp:3501-3509
Publication Date(Web):February 17, 2016
DOI:10.1021/jacs.5b13394
We have designed a strategy for postsynthesis installation of the β-diketiminate (NacNac) functionality in a metal–organic framework (MOF) of UiO-topology. Metalation of the NacNac-MOF (I) with earth-abundant metal salts afforded the desired MOF-supported NacNac-M complexes (M = Fe, Cu, and Co) with coordination environments established by detailed EXAFS studies. The NacNac-Fe-MOF catalyst, I•Fe(Me), efficiently catalyzed the challenging intramolecular sp3 C–H amination of a series of alkyl azides to afford α-substituted pyrrolidines. The NacNac-Cu-MOF catalyst, I•Cu(THF), was effective in promoting the intermolecular sp3 C–H amination of cyclohexene using unprotected anilines to provide access to secondary amines in excellent selectivity. Finally, the NacNac-Co-MOF catalyst, I•Co(H), was used to catalyze alkene hydrogenation with turnover numbers (TONs) as high as 700 000. All of the NacNac-M-MOF catalysts were more effective than their analogous homogeneous catalysts and could be recycled and reused without a noticeable decrease in yield. The NacNac-MOFs thus provide a novel platform for engineering recyclable earth-abundant-element-based single-site solid catalysts for many important organic transformations.
Co-reporter:Kuntal Manna; Pengfei Ji; Francis X. Greene
Journal of the American Chemical Society 2016 Volume 138(Issue 24) pp:7488-7491
Publication Date(Web):June 10, 2016
DOI:10.1021/jacs.6b03689
Here we present the first example of a single-site main group catalyst stabilized by a metal–organic framework (MOF) for organic transformations. The straightforward metalation of the secondary building units of a Zr-MOF with Me2Mg affords a highly active and reusable solid catalyst for hydroboration of carbonyls and imines and for hydroamination of aminopentenes. Impressively, the Mg-functionalized MOF displayed very high turnover numbers of up to 8.4 × 104 for ketone hydroboration and could be reused more than 10 times. MOFs can thus be used to develop novel main group solid catalysts for sustainable chemical synthesis.
Co-reporter:Ruoyu Xu; Youfu Wang; Xiaopin Duan; Kuangda Lu; Daniel Micheroni; Aiguo Hu
Journal of the American Chemical Society 2016 Volume 138(Issue 7) pp:2158-2161
Publication Date(Web):February 11, 2016
DOI:10.1021/jacs.5b13458
We report the design of a phosphorescence/fluorescence dual-emissive nanoscale metal–organic framework (NMOF), R-UiO, as an intracellular oxygen (O2) sensor. R-UiO contains a Pt(II)-porphyrin ligand as an O2-sensitive probe and a Rhodamine-B isothiocyanate ligand as an O2-insensitive reference probe. It exhibits good crystallinity, high stability, and excellent ratiometric luminescence response to O2 partial pressure. In vitro experiments confirmed the applicability of R-UiO as an intracellular O2 biosensor. This work is the first report of a NMOF-based intracellular oxygen sensor and should inspire the design of ratiometric NMOF sensors for other important analytes in biological systems.
Co-reporter:Teng Zhang; Kuntal Manna
Journal of the American Chemical Society 2016 Volume 138(Issue 9) pp:3241-3249
Publication Date(Web):February 11, 2016
DOI:10.1021/jacs.6b00849
New and active earth-abundant metal catalysts are critically needed to replace precious metal-based catalysts for sustainable production of commodity and fine chemicals. We report here the design of highly robust, active, and reusable cobalt-bipyridine- and cobalt-phenanthroline-based metal–organic framework (MOF) catalysts for alkene hydrogenation and hydroboration, aldehyde/ketone hydroboration, and arene C–H borylation. In alkene hydrogenation, the MOF catalysts tolerated a variety of functional groups and displayed unprecedentedly high turnover numbers of ∼2.5 × 106 and turnover frequencies of ∼1.1 × 105 h–1. Structural, computational, and spectroscopic studies show that site isolation of the highly reactive (bpy)Co(THF)2 species in the MOFs prevents intermolecular deactivation and stabilizes solution-inaccessible catalysts for broad-scope organic transformations. Computational, spectroscopic, and kinetic evidence further support a hitherto unknown (bpy•–)CoI(THF)2 ground state that coordinates to alkene and dihydrogen and then undergoing σ-complex-assisted metathesis to form (bpy)Co(alkyl)(H). Reductive elimination of alkane followed by alkene binding completes the catalytic cycle. MOFs thus provide a novel platform for discovering new base-metal molecular catalysts and exhibit enormous potential in sustainable chemical catalysis.
Co-reporter:Zhi-Ming Zhang, Xiaopin Duan, Shuang Yao, Zhishu Wang, Zekai Lin, Yang-Guang Li, La-Sheng Long, En-Bo Wang and Wenbin Lin
Chemical Science 2016 vol. 7(Issue 7) pp:4220-4229
Publication Date(Web):09 Mar 2016
DOI:10.1039/C5SC04408A
We report the crystallization of homochiral polyoxometalate (POM) macroanions {CoSb6O4(H2O)3[Co(hmta)SbW8O31]3}15− (1, hmta = hexamethylenetetramine) via the counter cation-mediated chiral symmetry breaking and asymmetric autocatalytic processes. In the presence of low Co2+ concentrations both Δ- and Λ-enantiomers of 1 formed in the reaction, crystallizing into the racemic crystal rac-1. At a high Co2+ concentration, the polyoxoanion enantiomers showed a high level of chiral recognition via H-bonding interactions to crystallize into enantiopure crystals of Δ- or Λ-[Co(H2O)6{CoSb6O4(H2O)3[Co(hmta)SbW8O31]3}]13−. During crystallization, a microscale symmetry-breaking event and a nonlinear asymmetric autocatalysis process make the enantiomers crystallize in different batches, which provides an opportunity to isolate the homochiral bulk materials. The defined structures of the racemic and homochiral crystals thus provide a molecular-level illustration that H-bonding interactions are responsible for such high-level chiral recognition, in a process similar to the supramolecular chirality frequently observed in biology. These POM macroanions showed a high cytotoxicity against various cancer cells, particularly ovarian cancer cells. The antitumor activity of these compounds resulted at least in part from the activation of the apoptotic pathways, as shown by the flow cytometry, Annexin V staining, DNA ladder, and TUNEL assay, likely by blocking the cell cycle and complexing with proteins in cells. The POM macroanions reported herein provide promising and novel antitumor agents for the potential treatment of various cancers.
Co-reporter:Bing An, Kang Cheng, Cheng Wang, Ye Wang, and Wenbin Lin
ACS Catalysis 2016 Volume 6(Issue 6) pp:3610
Publication Date(Web):April 19, 2016
DOI:10.1021/acscatal.6b00464
We prepared highly active catalysts for Fischer–Tropsch (FT) synthesis through the pyrolysis of iron-containing metal–organic frameworks (MOFs). The Fe-time yields of the nitrogen-doped catalyst were as high as 720 μmolCO gFe–1 s–1 under the conditions of 300 °C, 2 MPa, and H2/CO = 1, which is a value that surpasses that of most FT catalysts reported in the literature. The pyrolysis of the MOFs yielded nanoparticles with a unique iron oxide@iron carbide core–shell structure dispersed on carbon supports. Such a structure is favorable for FT synthesis and has never been reported previously. Our strategy resolved the problem that the strong metal–support interactions that are usually required to stabilize dispersed particles in calcination compromise the catalytic activity, because of the difficulty of reducing metal oxides. Moreover, we found full coverage of carbonates on the particle surfaces, which likely result from decarboxylation of the MOFs and further stabilize the particles before decomposing to CO2, leaving an active surface rich with dangling bonds for catalytic turnover.Keywords: core−shell; Fischer−Tropsch synthesis; iron oxide@iron carbide nanoparticles; metal−organic frameworks; pyrolysis; weak interaction
Co-reporter:Chao Zhang, Bing An, Ling Yang, Binbin Wu, Wei Shi, Yu-Cheng Wang, La-Sheng Long, Cheng Wang and Wenbin Lin
Journal of Materials Chemistry A 2016 vol. 4(Issue 12) pp:4457-4463
Publication Date(Web):16 Feb 2016
DOI:10.1039/C6TA00768F
We report the first synthesis of sulfurated porous carbon materials with well-defined morphologies and uniform N/S distributions via pyrolysis of zeolitic imidazolate frameworks loaded with sulfur-containing molecules. The optimized sulfurated catalyst demonstrates excellent electrocatalytic activity for the oxygen reduction reaction (ORR) in both acid and alkaline media. The sulfurization process under optimized conditions can lower the ORR over-potential by ca. 170 mV at 3 mA cm−2, giving a non-precious metal catalyst with an onset ORR potential of 0.90 V (vs. RHE, similarly hereinafter)/half-wave potential of 0.78 V in 0.1 M HClO4 and an onset ORR potential of 0.98 V/half-wave potential of 0.88 V in 0.1 M KOH. Furthermore, the S-doped porous carbon materials perform better in the long-term durability test than the non-S-doped samples and standard commercially available Pt/C. We also discuss different sulfuration methods for the ZIF system, morphologies of pyrolyzed samples, and catalytically active sites.
Co-reporter:Xin Zhou, Daniel Micheroni, Zekai Lin, Christopher Poon, Zhong Li, and Wenbin Lin
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 6) pp:4192
Publication Date(Web):January 22, 2016
DOI:10.1021/acsami.5b11958
We report the synthesis of fac-M(4-amino-bipy)(CO)3X (M = Mn and X = Br or M = Re and X = Cl, with bipy = 2,2′-bipyridine), their immobilization on graphene oxide (GrO) via diazonium grafting, and the use of Re-functionalized GrO for electrocatalytic syngas production. Infrared (IR) spectroscopy, X-ray absorption fine structure (XAFS) spectroscopy, and electrocatalysis indicated successful grafting of the Re catalyst onto GrO. Re-functionalized GrO was then deposited onto a glassy carbon electrode (GCE) for CO2 reduction. Investigation of the Re-functionalized GCE for syngas production was performed in a CO2-saturated acetonitrile solution with 3.1 M H2O as the proton source and 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) as the supporting electrolyte. Cyclic voltammetry (CV), controlled potential electrolysis (CPE), and gas chromatography (GC) were employed to determine its CO2-to-CO conversion performance. The Re catalyst shows a turnover frequency (TOF) for generating CO up to 4.44 s–1 with a CO/H2 ratio of 7:5.Keywords: catalysis; CO2 reduction; diazonium grafting; graphene; syngas
Co-reporter:Wenbin Lin and Jeffrey R. Long
Inorganic Chemistry 2016 Volume 55(Issue 15) pp:7189
Publication Date(Web):August 1, 2016
DOI:10.1021/acs.inorgchem.6b01680
Co-reporter:Christopher Poon, Xiaopin Duan, Christina Chan, Wenbo Han, and Wenbin Lin
Molecular Pharmaceutics 2016 Volume 13(Issue 11) pp:3665-3675
Publication Date(Web):October 6, 2016
DOI:10.1021/acs.molpharmaceut.6b00466
Due to the ability of ovarian cancer (OCa) to acquire drug resistance, it has been difficult to develop efficient and safe chemotherapy for OCa. Here, we examined the therapeutic use of a new self-assembled core–shell nanoscale coordination polymer nanoparticle (NCP-Carbo/GMP) that delivers high loadings of carboplatin (28.0 ± 2.6 wt %) and gemcitabine monophosphate (8.6 ± 1.5 wt %). A strong synergistic effect was observed between carboplatin and gemcitabine against platinum-resistant OCa cells, SKOV-3 and A2780/CDPP, in vitro. The coadministration of carboplatin and gemcitabine in the NCP led to prolonged blood circulation half-life (11.8 ± 4.8 h) and improved tumor uptake of the drugs (10.2 ± 4.4% ID/g at 24 h), resulting in 71% regression and 80% growth inhibition of SKOV-3 and A2780/CDDP tumors, respectively. Our findings demonstrate that NCP particles provide great potential for the codelivery of multiple chemotherapeutics for treating drug-resistant cancer.Keywords: carboplatin; gemcitabine; nanoscale coordination polymers; platinum-resistant ovarian cancer; synergistic effect;
Co-reporter:Marek Piechowicz, Carter W. Abney, Xin Zhou, Nathan C. Thacker, Zhong Li, and Wenbin Lin
Industrial & Engineering Chemistry Research 2016 Volume 55(Issue 15) pp:4170
Publication Date(Web):November 19, 2015
DOI:10.1021/acs.iecr.5b03304
Informed by density functional theory calculations, a novel bifunctional chelator, (Z)-2-[2-(N′-hydroxycarbamimidoyl)phenoxy]benzoic acid, was designed and synthesized for ultrahigh uranium uptake from seawater. Investigation of the ligand for uranium sorption was conducted in artificial seawater (pH = 8.2). An exceptional uranium uptake of 553 mg of uranium (g of sorbent)−1 was obtained with a theoretical saturation capacity of 710 mg g–1 obtained by fitting isotherm data with the Langmuir–Freundlich model. The resulting yellow precipitate was characterized via X-ray absorption fine structure (XAFS) at the U LIII-edge, with the extended XAFS spectra best fitted by a model where uranyl is coordinated by monodentate amidoxime, one chelating carboxylic acid, and two water molecules. These results are consistent with the formation of a uranium coordination polymer. The ultrahigh uranium uptake capacity obtained by the bifunctional chelating ligand makes it a promising candidate for deployment as a uranium adsorbent.
Co-reporter:Dr. Xiang-Jian Kong;Zekai Lin;Dr. Zhi-Ming Zhang;Teng Zhang; Wenbin Lin
Angewandte Chemie 2016 Volume 128( Issue 22) pp:6521-6526
Publication Date(Web):
DOI:10.1002/ange.201600431
Abstract
Metal–organic frameworks (MOFs) provide a tunable platform for hierarchically integrating multiple components to effect synergistic functions that cannot be achieved in solution. Here we report the encapsulation of a Ni-containing polyoxometalate (POM) [Ni4(H2O)2(PW9O34)2]10− (Ni4P2) into two highly stable and porous phosphorescent MOFs. The proximity of Ni4P2 to multiple photosensitizers in Ni4P2@MOF allows for facile multi-electron transfer to enable efficient visible-light-driven hydrogen evolution reaction (HER) with turnover numbers as high as 1476. Photophysical and electrochemical studies established the oxidative quenching of the excited photosensitizer by Ni4P2 as the initiating step of HER and explained the drastic catalytic activity difference of the two POM@MOFs. Our work shows that POM@MOF assemblies not only provide a tunable platform for designing highly effective photocatalytic HER catalysts but also facilitate detailed mechanistic understanding of HER processes.
Co-reporter:Dr. Xiang-Jian Kong;Zekai Lin;Dr. Zhi-Ming Zhang;Teng Zhang; Wenbin Lin
Angewandte Chemie International Edition 2016 Volume 55( Issue 22) pp:6411-6416
Publication Date(Web):
DOI:10.1002/anie.201600431
Abstract
Metal–organic frameworks (MOFs) provide a tunable platform for hierarchically integrating multiple components to effect synergistic functions that cannot be achieved in solution. Here we report the encapsulation of a Ni-containing polyoxometalate (POM) [Ni4(H2O)2(PW9O34)2]10− (Ni4P2) into two highly stable and porous phosphorescent MOFs. The proximity of Ni4P2 to multiple photosensitizers in Ni4P2@MOF allows for facile multi-electron transfer to enable efficient visible-light-driven hydrogen evolution reaction (HER) with turnover numbers as high as 1476. Photophysical and electrochemical studies established the oxidative quenching of the excited photosensitizer by Ni4P2 as the initiating step of HER and explained the drastic catalytic activity difference of the two POM@MOFs. Our work shows that POM@MOF assemblies not only provide a tunable platform for designing highly effective photocatalytic HER catalysts but also facilitate detailed mechanistic understanding of HER processes.
Co-reporter:Wenbin Lin
Chemical Reviews 2015 Volume 115(Issue 19) pp:10407
Publication Date(Web):October 14, 2015
DOI:10.1021/acs.chemrev.5b00534
Co-reporter:Chunbai He, Demin Liu, and Wenbin Lin
Chemical Reviews 2015 Volume 115(Issue 19) pp:11079
Publication Date(Web):August 27, 2015
DOI:10.1021/acs.chemrev.5b00125
Co-reporter:Kuangda Lu; Chunbai He
Journal of the American Chemical Society 2015 Volume 137(Issue 24) pp:7600-7603
Publication Date(Web):June 12, 2015
DOI:10.1021/jacs.5b04069
We report here the rational design of the first chlorin-based nanoscale metal–organic framework (NMOF), DBC-UiO, with much improved photophysical properties over the previously reported porphyrin-based NMOF, DBP-UiO. Reduction of the DBP ligands in DBP-UiO to the DBC ligands in DBC-UiO led to a 13 nm red shift and an 11-fold increase in the extinction coefficient of the lowest-energy Q band. While inheriting the crystallinity, stability, porosity, and nanoplate morphology of DBP-UiO, DBC-UiO sensitizes more efficient 1O2 generation and exhibits significantly enhanced photodynamic therapy (PDT) efficacy on two colon cancer mouse models as a result of its improved photophysical properties. Both apoptosis and immunogenic cell death contributed to killing of cancer cells in DBC-UiO-induced PDT.
Co-reporter:Kuntal Manna; Teng Zhang; Francis X. Greene
Journal of the American Chemical Society 2015 Volume 137(Issue 7) pp:2665-2673
Publication Date(Web):February 2, 2015
DOI:10.1021/ja512478y
We report here the synthesis of a series of robust and porous bipyridyl- and phenanthryl-based metal–organic frameworks (MOFs) of UiO topology (BPV-MOF, mBPV-MOF, and mPT-MOF) and their postsynthetic metalation to afford highly active single-site solid catalysts. While BPV-MOF was constructed from only bipyridyl-functionalized dicarboxylate linker, both mBPV- and mPT-MOF were built with a mixture of bipyridyl- or phenanthryl-functionalized and unfunctionalized dicarboxylate linkers. The postsynthetic metalation of these MOFs with [Ir(COD)(OMe)]2 provided Ir-functionalized MOFs (BPV-MOF-Ir, mBPV-MOF-Ir, and mPT-MOF-Ir), which are highly active catalysts for tandem hydrosilylation of aryl ketones and aldehydes followed by dehydrogenative ortho-silylation of benzylicsilyl ethers as well as C–H borylation of arenes using B2pin2. Both mBPV-MOF-Ir and mPT-MOF-Ir catalysts displayed superior activities compared to BPV-MOF-Ir due to the presence of larger open channels in the mixed-linker MOFs. Impressively, mBPV-MOF-Ir exhibited high TONs of up to 17000 for C–H borylation reactions and was recycled more than 15 times. The mPT-MOF-Ir system is also active in catalyzing tandem dehydrosilylation/dehydrogenative cyclization of N-methylbenzyl amines to azasilolanes in the absence of a hydrogen acceptor. Importantly, MOF-Ir catalysts are significantly more active (up to 95 times) and stable than their homogeneous counterparts for all three reactions, strongly supporting the beneficial effects of active site isolation within MOFs. This work illustrates the ability to increase MOF open channel sizes by using the mixed linker approach and shows the enormous potential of developing highly active and robust single-site solid catalysts based on MOFs containing nitrogen-donor ligands for important organic transformations.
Co-reporter:Takahiro Sawano; Nathan C. Thacker; Zekai Lin; Alexandra R. McIsaac
Journal of the American Chemical Society 2015 Volume 137(Issue 38) pp:12241-12248
Publication Date(Web):September 3, 2015
DOI:10.1021/jacs.5b09225
We report here the design of BINAP-based metal–organic frameworks and their postsynthetic metalation with Rh complexes to afford highly active and enantioselective single-site solid catalysts for the asymmetric cyclization reactions of 1,6-enynes. Robust, chiral, and porous Zr-MOFs of UiO topology, BINAP-MOF (I) or BINAP-dMOF (II), were prepared using purely BINAP-derived dicarboxylate linkers or by mixing BINAP-derived linkers with unfunctionalized dicarboxylate linkers, respectively. Upon metalation with Rh(nbd)2BF4 and [Rh(nbd)Cl]2/AgSbF6, the MOF precatalysts I·Rh(BF4) and I·Rh(SbF6) efficiently catalyzed highly enantioselective (up to 99% ee) reductive cyclization and Alder-ene cycloisomerization of 1,6-enynes, respectively. I·Rh catalysts afforded cyclization products at comparable enantiomeric excesses (ee’s) and 4–7 times higher catalytic activity than the homogeneous controls, likely a result of catalytic site isolation in the MOF which prevents bimolecular catalyst deactivation pathways. However, I·Rh is inactive in the more sterically encumbered Pauson–Khand reactions between 1,6-enynes and carbon monoxide. In contrast, with a more open structure, Rh-functionalized BINAP-dMOF, II·Rh, effectively catalyzed Pauson–Khand cyclization reactions between 1,6-enynes and carbon monoxide at 10 times higher activity than the homogeneous control. II·Rh was readily recovered and used three times in Pauson–Khand cyclization reactions without deterioration of yields or ee’s. Our work has expanded the scope of MOF-catalyzed asymmetric reactions and showed that the mixed linker strategy can effectively enlarge the open space around the catalytic active site to accommodate highly sterically demanding polycyclic metallocycle transition states/intermediates in asymmetric intramolecular cyclization reactions.
Co-reporter:Zhi-Ming Zhang; Teng Zhang; Cheng Wang; Zekai Lin; La-Sheng Long
Journal of the American Chemical Society 2015 Volume 137(Issue 9) pp:3197-3200
Publication Date(Web):February 24, 2015
DOI:10.1021/jacs.5b00075
A simple and effective charge-assisted self-assembly process was developed to encapsulate a noble-metal-free polyoxometalate (POM) inside a porous and phosphorescent metal–organic framework (MOF) built from [Ru(bpy)3]2+-derived dicarboxylate ligands and Zr6(μ3-O)4(μ3-OH)4 secondary building units. Hierarchical organization of photosensitizing and catalytic proton reduction components in such a POM@MOF assembly enables fast multielectron injection from the photoactive framework to the encapsulated redox-active POMs upon photoexcitation, leading to efficient visible-light-driven hydrogen production. Such a modular and tunable synthetic strategy should be applicable to the design of other multifunctional MOF materials with potential in many applications.
Co-reporter:Takahiro Sawano, Pengfei Ji, Alexandra R. McIsaac, Zekai Lin, Carter W. Abney and Wenbin Lin
Chemical Science 2015 vol. 6(Issue 12) pp:7163-7168
Publication Date(Web):14 Sep 2015
DOI:10.1039/C5SC02100F
We have designed the first chiral diene-based metal–organic framework (MOF), E2-MOF, and postsynthetically metalated E2-MOF with Rh(I) complexes to afford highly active and enantioselective single-site solid catalysts for C–C bond formation reactions. Treatment of E2-MOF with [RhCl(C2H4)2]2 led to a highly enantioselective catalyst for 1,4-additions of arylboronic acids to α,β-unsaturated ketones, whereas treatment of E2-MOF with Rh(acac)(C2H4)2 afforded a highly efficient catalyst for the asymmetric 1,2-additions of arylboronic acids to aldimines. Interestingly, E2-MOF·Rh(acac) showed higher activity and enantioselectivity than the homogeneous control catalyst, likely due to the formation of a true single-site catalyst in the MOF. E2-MOF·Rh(acac) was also successfully recycled and reused at least seven times without loss of yield and enantioselectivity.
Co-reporter:Xinping Lin, Yahui Hong, Chao Zhang, Ruiyun Huang, Cheng Wang and Wenbin Lin
Chemical Communications 2015 vol. 51(Issue 95) pp:16996-16999
Publication Date(Web):30 Sep 2015
DOI:10.1039/C5CC06453H
The 2,2′-bipyridyl moieties lining the channels of two designer metal–organic frameworks (MOFs), UiO-bpydc and Eu-bpydc (bpydc is 2,2′-bipyridine 5,5′-dicarboxylic acid), recognize and pre-concentrate metal ion analytes and, in the case of Eu-bpydc, transfer energy to the Eu3+ centers, to provide highly sensitive luminescence sensors for transition metal ions.
Co-reporter:Chao Zhang, Yahui Hong, Ruihan Dai, Xinping Lin, La-Sheng Long, Cheng Wang, and Wenbin Lin
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 21) pp:11648
Publication Date(Web):May 12, 2015
DOI:10.1021/acsami.5b02899
A highly active hydrogen evolution reaction (HER) electrode with low Pt loading on glassy carbon (GC) has been prepared by anodic platinum dissolution and co-deposition of polyoxometalates. TEM, EDS, XPS, CV, and ICP-MS analyses gave a Pt loading of 50–100 ng/cm2, corresponding to a Pt coverage of only 0.08–0.16 monolayer. With an overpotential of 65 mV at 20 mA/cm2, the modified GC has a HER activity comparable to that of the commercial Pt working electrode.Keywords: anodic platinum dissolution; hydrogen evolution reaction; polyoxometalate;
Co-reporter:Christopher Poon, Chunbai He, Demin Liu, Kuangda Lu, Wenbin Lin
Journal of Controlled Release 2015 Volume 201() pp:90-99
Publication Date(Web):10 March 2015
DOI:10.1016/j.jconrel.2015.01.026
Gemcitabine has long been the standard of care for treating pancreatic ductal adenocarcinoma (PDAC), despite its poor pharmacokinetics/dynamics and rapid development of drug resistance. In this study, we have developed a novel nanoparticle platform based on nanoscale coordination polymer-1 (NCP-1) for simultaneous delivery of two chemotherapeutics, oxaliplatin and gemcitabine monophosphate (GMP), at 30 wt.% and 12 wt.% drug loadings, respectively. A strong synergistic therapeutic effect of oxaliplatin and GMP was observed in vitro against AsPc-1 and BxPc-3 pancreatic cancer cells. NCP-1 particles effectively avoid uptake by the mononuclear phagocyte system (MPS) in vivo with a long blood circulation half-life of 10.1 ± 3.3 h, and potently inhibit tumor growth when compared to NCP particles carrying oxaliplatin or GMP alone. Our findings demonstrate NCP-1 as a novel nanocarrier for the co-delivery of two chemotherapeutics that have distinctive mechanisms of action to simultaneously disrupt multiple anticancer pathways with maximal therapeutic efficacy and minimal side effects.
Co-reporter:Xinping Lin, Qiongqiong Zhang, Jiahe Chen, Xiangjian Kong, La-Sheng Long, Cheng Wang and Wenbin Lin
RSC Advances 2015 vol. 5(Issue 4) pp:2914-2919
Publication Date(Web):28 Nov 2014
DOI:10.1039/C4RA07853E
Three multinuclear gadolinium(III) clusters containing the nicotinate (nic) ligand, [Gd2(nic)6(H2O)4] (1), [Gd4(μ3-OH)4(Hnic)5(H2O)12](ClO4)8·7H2O (2), and [Gd4(μ3-OH)4(nic)6(H2O)6]2(ClO4)4·4H2O (3) were synthesized and characterized. Potential applications of these Gd(III) clusters as high-field magnetic resonance imaging (MRI) contrast agents were evaluated. The longitudinal relaxivities (r1) of 1–3 in water at 7 T were determined to be 10.45 ± 0.16, 9.28 ± 0.06, and 2.04 ± 0.29 mM−1 s−1 on a per Gd ion basis, respectively. In 1% agarose solution, the r1 values increased slightly to 10.37 ± 0.31, 10.74 ± 0.11, and 4.60 ± 0.29 mM−1 s−1 for 1–3, respectively. The ability to tune the number of inner-sphere water molecules, cluster sizes, organic ligands, and Gd coordination modes in such Gd(III) clusters provide interesting opportunities to further enhance the MR relaxivities for potential MRI applications.
Co-reporter:Chunbai He, Demin Liu, Wenbin Lin
Biomaterials 2015 36() pp: 124-133
Publication Date(Web):
DOI:10.1016/j.biomaterials.2014.09.017
Co-reporter:Chunbai He, Demin Liu, and Wenbin Lin
ACS Nano 2015 Volume 9(Issue 1) pp:991
Publication Date(Web):January 5, 2015
DOI:10.1021/nn506963h
Combination therapy enhances anticancer efficacy of both drugs via synergistic effects. We report here nanoscale coordination polymer (NCP)-based core–shell nanoparticles carrying high payloads of cisplatin and the photosensitizer pyrolipid, NCP@pyrolipid, for combined chemotherapy and photodynamic therapy (PDT). NCP@pyrolipid releases cisplatin and pyrolipid in a triggered manner to synergistically induce cancer cell apoptosis and necrosis. In vivo pharmacokinetic and biodistribution studies in mice show prolonged blood circulation times, low uptake in normal organs, and high tumor accumulation of cisplatin and pyrolipid. Compared to monotherapy, NCP@pyrolipid shows superior potency and efficacy in tumor regression (83% reduction in tumor volume) at low drug doses in the cisplatin-resistant human head and neck cancer SQ20B xenograft murine model. We elucidated the in vitro/vivo fate of the lipid layer and its implications on the mechanisms of actions. This study suggests multifunctional NCP core–shell nanoparticles as a versatile and effective drug delivery system for potential translation to the clinic.Keywords: combination of chemotherapy and photodynamic therapy; core−shell nanostructure; nanoscale coordination polymer; tumor regression;
Co-reporter:Teng Zhang and Wenbin Lin
Chemical Society Reviews 2014 vol. 43(Issue 16) pp:5982-5993
Publication Date(Web):28 Apr 2014
DOI:10.1039/C4CS00103F
Solar energy is an alternative, sustainable energy source for mankind. Finding a convenient way to convert sunlight energy into chemical energy is a key step towards realizing large-scale solar energy utilization. Owing to their structural regularity and synthetic tunability, metal–organic frameworks (MOFs) provide an interesting platform to hierarchically organize light-harvesting antennae and catalytic centers to achieve solar energy conversion. Such photo-driven catalytic processes not only play a critical role in the solar to chemical energy conversion scheme, but also provide a novel methodology for the synthesis of fine chemicals. In this review, we summarize the fundamental principles of energy transfer and photocatalysis and provide an overview of the latest progress in energy transfer, light-harvesting, photocatalytic proton and CO2 reduction, and water oxidation using MOFs. The applications of MOFs in organic photocatalysis and degradation of model organic pollutants are also discussed.
Co-reporter:C. W. Abney;J. C. Gilhula;K. Lu ;W. Lin
Advanced Materials 2014 Volume 26( Issue 47) pp:7993-7997
Publication Date(Web):
DOI:10.1002/adma.201403428
Co-reporter:Kuntal Manna ; Teng Zhang ; Michaël Carboni ; Carter W. Abney
Journal of the American Chemical Society 2014 Volume 136(Issue 38) pp:13182-13185
Publication Date(Web):September 4, 2014
DOI:10.1021/ja507947d
A robust and porous Zr metal–organic framework, sal-MOF, of UiO topology was synthesized using a salicylaldimine (sal)-derived dicarboxylate bridging ligand. Postsynthetic metalation of sal-MOF with iron(II) or cobalt(II) chloride followed by treatment with NaBEt3H in THF resulted in Fe- and Co-functionalized MOFs (sal-M-MOF, M = Fe, Co) which are highly active solid catalysts for alkene hydrogenation. Impressively, sal-Fe-MOF displayed very high turnover numbers of up to 145000 and was recycled and reused more than 15 times. This work highlights the unique opportunity of developing MOF-based earth-abundant catalysts for sustainable chemical synthesis.
Co-reporter:Kuntal Manna ; Teng Zhang
Journal of the American Chemical Society 2014 Volume 136(Issue 18) pp:6566-6569
Publication Date(Web):April 23, 2014
DOI:10.1021/ja5018267
We have designed highly stable and recyclable single-site solid catalysts via postsynthetic metalation of the 2,2′-bipyridyl-derived metal–organic framework (MOF) of the UiO structure (bpy-UiO). The Ir-functionalized MOF (bpy-UiO-Ir) is a highly active catalyst for both borylation of aromatic C–H bonds using B2(pin)2 (pin = pinacolate) and ortho-silylation of benzylicsilyl ethers; the ortho-silylation activity of the bpy-UiO-Ir is at least 3 orders of magnitude higher than that of the homogeneous control. The Pd-functionalized MOF (bpy-UiO-Pd) catalyzes the dehydrogenation of substituted cyclohexenones to afford phenol derivatives with oxygen as the oxidant. Most impressively, the bpy-UiO-Ir was recycled and reused 20 times for the borylation reaction without loss of catalytic activity or MOF crystallinity. This work highlights the opportunity in designing highly stable and active catalysts based on MOFs containing nitrogen donor ligands for important organic transformations.
Co-reporter:Joseph M. Falkowski ; Takahiro Sawano ; Teng Zhang ; Galen Tsun ; Yuan Chen ; Jenny V. Lockard
Journal of the American Chemical Society 2014 Volume 136(Issue 14) pp:5213-5216
Publication Date(Web):March 31, 2014
DOI:10.1021/ja500090y
A robust and porous Zr metal–organic framework (MOF) based on a BINAP-derived dicarboxylate linker, BINAP-MOF, was synthesized and post-synthetically metalated with Ru and Rh complexes to afford highly enantioselective catalysts for important organic transformations. The Rh-functionalized MOF is not only highly enantioselective (up to >99% ee) but also 3 times as active as the homogeneous control. XAFS studies revealed that the Ru-functionalized MOF contains Ru-BINAP precatalysts with the same coordination environment as the homogeneous Ru complex. The post-synthetically metalated BINAP-MOFs provide a versatile family of single-site solid catalysts for catalyzing a broad scope of asymmetric organic transformations, including addition of aryl and alkyl groups to α,β-unsaturated ketones and hydrogenation of substituted alkene and carbonyl compounds.
Co-reporter:Chunbai He ; Kuangda Lu ; Demin Liu
Journal of the American Chemical Society 2014 Volume 136(Issue 14) pp:5181-5184
Publication Date(Web):March 26, 2014
DOI:10.1021/ja4098862
Ovarian cancer is the leading cause of death among women with gynecological malignancies. Acquired resistance to chemotherapy is a major limitation for ovarian cancer treatment. We report here the first use of nanoscale metal–organic frameworks (NMOFs) for the co-delivery of cisplatin and pooled small interfering RNAs (siRNAs) to enhance therapeutic efficacy by silencing multiple drug resistance (MDR) genes and resensitizing resistant ovarian cancer cells to cisplatin treatment. UiO NMOFs with hexagonal-plate morphologies were loaded with a cisplatin prodrug and MDR gene-silencing siRNAs (Bcl-2, P-glycoprotein [P-gp], and survivin) via encapsulation and surface coordination, respectively. NMOFs protect siRNAs from nuclease degradation, enhance siRNA cellular uptake, and promote siRNA escape from endosomes to silence MDR genes in cisplatin-resistant ovarian cancer cells. Co-delivery of cisplatin and siRNAs with NMOFs led to an order of magnitude enhancement in chemotherapeutic efficacy in vitro, as indicated by cell viability assay, DNA laddering, and Annexin V staining. This work shows that NMOFs hold great promise in the co-delivery of multiple therapeutics for effective treatment of drug-resistant cancers.
Co-reporter:Kuangda Lu, Chunbai He, and Wenbin Lin
Journal of the American Chemical Society 2014 Volume 136(Issue 48) pp:16712-16715
Publication Date(Web):November 19, 2014
DOI:10.1021/ja508679h
Photodynamic therapy (PDT) is an effective anticancer procedure that relies on tumor localization of a photosensitizer followed by light activation to generate cytotoxic reactive oxygen species (e.g., 1O2). Here we report the rational design of a Hf–porphyrin nanoscale metal–organic framework, DBP–UiO, as an exceptionally effective photosensitizer for PDT of resistant head and neck cancer. DBP–UiO efficiently generates 1O2 owing to site isolation of porphyrin ligands, enhanced intersystem crossing by heavy Hf centers, and facile 1O2 diffusion through porous DBP–UiO nanoplates. Consequently, DBP–UiO displayed greatly enhanced PDT efficacy both in vitro and in vivo, leading to complete tumor eradication in half of the mice receiving a single DBP–UiO dose and a single light exposure. NMOFs thus represent a new class of highly potent PDT agents and hold great promise in treating resistant cancers in the clinic.
Co-reporter:Cheng Wang ; Olga Volotskova ; Kuangda Lu ; Moiz Ahmad ; Conroy Sun ; Lei Xing
Journal of the American Chemical Society 2014 Volume 136(Issue 17) pp:6171-6174
Publication Date(Web):April 14, 2014
DOI:10.1021/ja500671h
We have designed two metal–organic frameworks (MOFs) to efficiently convert X-ray to visible-light luminescence. The MOFs are constructed from M6(μ3-O)4(μ3-OH)4(carboxylate)12 (M = Hf or Zr) secondary building units (SBUs) and anthracene-based dicarboxylate bridging ligands. The high atomic number of Zr and Hf in the SBUs serves as effective X-ray antenna by absorbing X-ray photons and converting them to fast electrons through the photoelectric effect. The generated electrons then excite multiple anthracene-based emitters in the MOF through inelastic scattering, leading to efficient generation of detectable photons in the visible spectrum. The MOF materials thus serve as efficient X-ray scintillators via synergistic X-ray absorption by the metal-cluster SBUs and optical emission by the bridging ligands.
Co-reporter:Carter W. Abney, Kathryn M. L. Taylor-Pashow, Shane R. Russell, Yuan Chen, Raghabendra Samantaray, Jenny V. Lockard, and Wenbin Lin
Chemistry of Materials 2014 Volume 26(Issue 18) pp:5231
Publication Date(Web):August 29, 2014
DOI:10.1021/cm501894h
Innovative solid-phase sorbent technologies are needed to extract radionuclides from harsh media for environmental remediation and in order to close the nuclear fuel cycle. Highly porous inorganic materials with remarkable sorptive properties have been prepared by topotactic transformations of metal–organic frameworks (MOFs) using both basic and acidic solutions. Treatment of Ti and Zr nanoMOFs with NaOH, Na3PO4, and H3PO4 yields Ti and Zr oxides, oxyphosphates, and phosphates via sacrificial removal of the organic ligands. This controlled ligand extraction process results in porous inorganic materials, which preserve the original MOF morphologies and impart useful surface functionalities, but are devoid of organic linkers. Structural investigation by X-ray absorption spectroscopy reveals preservation of the coordination environment of the scattering metal. Changing the MOF template introduces different metal and structural possibilities, while application of different digest solutions allows preparation of metal oxides, metal oxyphosphates, and metal phosphates. The high stability and porosity of these novel materials makes them ideally suited as nanosorbents in severe environments. Their potential for several radionuclide separations is demonstrated, including decontamination of high level nuclear waste, extraction of lanthanides, and remediation of radionuclide-contaminated seawater.
Co-reporter:Demin Liu, Chunbai He, Christopher Poon and Wenbin Lin
Journal of Materials Chemistry A 2014 vol. 2(Issue 46) pp:8249-8255
Publication Date(Web):08 Oct 2014
DOI:10.1039/C4TB00751D
Nanoscale coordination polymers (NCPs) are self-assembled from metal ions and organic bridging ligands. The tunable compositions, sizes, and shapes; high drug loadings; ease of surface modification; and intrinsic biodegradability make NCPs great candidates for nanomedicine applications. Here we report the self-assembly of a Mn-bisphosphonate NCP that carries exceptionally high loadings of zoledronate (63 ± 5 wt%) and Mn2+ ions (13 ± 4 wt%) for potential cancer therapy and magnetic resonance imaging, respectively. The Mn-bisphosphonate NCP was further coated with lipid and pegylated to control the drug release kinetics and functionalized with a targeting group (anisamide) to endow specificity to cancer cells, leading to significantly enhanced cytotoxicity against human breast and pancreatic cancer cells. In vitro MR imaging studies demonstrated the efficacy of the Mn-bisphosphonate NCP as an effective T1 contrast agent and confirmed the targeting capability of anisamide-functionalized NCP. Multifunctional NCPs thus present an excellent platform for designing theranostic nanomaterials for a wide range of biomedical applications.
Co-reporter:C. Zhang, X. Lin, Z. Zhang, L.-S. Long, C. Wang and W. Lin
Chemical Communications 2014 vol. 50(Issue 78) pp:11591-11594
Publication Date(Web):12 Aug 2014
DOI:10.1039/C4CC03487B
A novel organic–inorganic hybrid monocapped/bicapped Keggin structure [CoII(bpy)3]6(H2bpy)[(CoIIbpy)2(PMo8VIMo4VO40)]3 [(CoIIbpy)(PMo8VIMo4VO40)]·16H2O (bpy = 2,2′-bipyridine) was synthesized and shown to be an efficient visible light-driven catalyst for water oxidation.
Co-reporter:Xin Zhou, Teng Zhang, Carter W. Abney, Zhong Li, and Wenbin Lin
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 21) pp:18475
Publication Date(Web):October 27, 2014
DOI:10.1021/am506435u
Covalent anchoring of 2,2′-bipyridine (L) to a graphene (Gr) modified electrode followed by treatment with an Mx+(NO3)x solution (M = Fe3+, Co2+, Ni2+, or Cu2+) results in surface-bound catalysts with high redox activity in neutral water at ambient temperature. Raman and IR spectroscopies indicate the successful L grafting and Gr deposition onto the electrodes, whereas metal concentration was determined by inductively coupled plasma mass spectrometry (ICP-MS). Cyclic voltammetry measurements were used to investigate catalytic performances, whereas a rotating ring-disk electrode was used to measure the faraday efficiencies of oxygen evolution reaction and determine experimental turnover frequencies (TOFs). Of the four metal-L complexes investigated, Co-L on a Gr-modified indium tin oxide (ITO) electrode exhibits the best catalytic activity. Washing with a solution containing catalytically inert Zn2+ removes Co weakly bound by surface carboxylate functionalities, and ensures the presence of only covalently attached active catalytic species. This process results in an experimental TOF of 14 s–1 at an overpotential of 834 mV. Functionalization of Gr-modified electrodes with appropriate metal-binding moieties thus provides a feasible strategy for loading first row transition metals onto conductive surfaces for the generation of highly active water oxidation catalysts.Keywords: 1st row transition metal; electrochemistry; graphene; water oxidation catalyst
Co-reporter:Demin Liu, Kuangda Lu, Christopher Poon, and Wenbin Lin
Inorganic Chemistry 2014 Volume 53(Issue 4) pp:1916-1924
Publication Date(Web):November 19, 2013
DOI:10.1021/ic402194c
Metal–organic frameworks (MOFs) are a class of hybrid materials self-assembled from organic bridging ligands and metal ion/cluster connecting points. The combination of a variety of organic linkers, metal ions/clusters, and structural motifs can lead to an infinite array of new materials with interesting properties for many applications. In this Forum Article, we discuss the design and applications of MOFs in chemical sensing and biological imaging. The first half of this article focuses on the development of MOFs as chemical sensors by highlighting how unique attributes of MOFs can be utilized to enhance sensitivity and selectivity. We also discuss some of the issues that need to be addressed in order to develop practically useful MOF sensors. The second half of this article focuses on the design and applications of nanoscale MOFs (NMOFs) as imaging contrast agents. NMOFs possess several interesting attributes, such as high cargo loading capacity, ease of postmodification, tunable size and shape, and intrinsic biodegradability, to make them excellent candidates as imaging contrast agents. We discuss the use of representative NMOFs in magnetic resonance imaging (MRI), X-ray computed tomography (CT), and optical imaging. Although still in their infancy, we believe that the compositional tunability and mild synthetic conditions of NMOF imaging agents should greatly facilitate their further development for clinical translation.
Co-reporter:Cheng Wang, Demin Liu, Zhigang Xie, and Wenbin Lin
Inorganic Chemistry 2014 Volume 53(Issue 3) pp:1331-1338
Publication Date(Web):January 14, 2014
DOI:10.1021/ic402015q
Doping a functional ligand into a known crystalline system built from ligands of similar shape and length provides a powerful strategy to construct functional metal–organic frameworks (MOFs) with desired functionality and structural topology. This mix-and-match approach mimics the widely applied metal ion doping (or solid solution formation) in traditional inorganic materials, such as metal oxides, wherein maintaining charge balance of the doped lattice and ensuring size match between doped metal ions and the parent lattice are key to successful doping. In this work, we prepared three sterically demanding dicarboxylate ligands based on Ir/Ru-phosphors with similar structures and variable charges (−2 to 0), [Ir(ppy)3]-dicarboxylate (L1, ppy is 2-phenylpyridine), [Ir(bpy)(ppy)2]+-dicarboxylate (L2, bpy is 2,2′-bipyridine), and Ru(bpy)3]2+-dicarboxylate (L3), and successfully doped them into the known IRMOF-9/-10 structures by taking advantage of matching length between 4,4′-biphenyl dicarboxylate (BPDC) and L1–L3. We systematically investigated the effects of size and charge of the doping ligand on the MOF structures and the ligand doping levels in these MOFs. L1 carries a −2 charge to satisfy the charge requirement of the parent Zn4O(BPDC)3 framework and can be mixed into the IRMOF-9/-10 structure in the whole range of H2L1/H2BPDC ratios from 0 to 1. The steric bulk of L1 induces a phase transition from the interpenetrated IRMOF-9 structure to the non-interpenetrated IRMOF-10 counterpart. L2 and L3 do not match the dinegative charge of BPDC in order to maintain the charge balance for a neutral IRMOF-9/-10 framework and can only be doped into the IRMOF-9 structure to a certain degree. L2 and L3 form a charge-balanced new phase with a neutral framework structure at higher doping levels (>8% For L2 and >6% For L3). This systematic investigation reveals the influences of steric demand and charge balance on ligand doping in MOFs, a phenomenon that has been well-established in metal ion doping in traditional inorganic materials.
Co-reporter:Teng Zhang;Kathryn E. deKrafft;Jin-Liang Wang;Cheng Wang
European Journal of Inorganic Chemistry 2014 Volume 2014( Issue 4) pp:698-707
Publication Date(Web):
DOI:10.1002/ejic.201300882
Abstract
A series of [Ir(bpy)Cp*Cl]Cl (bpy: 2,2′-bipyridine; Cp*: pentamethylcyclopentadienyl) complexes with 4,4′- and 6,6′-substituents on the bipyridine ring were synthesized and used for water oxidation both electrochemically and with chemical oxidants. Under electrochemical water-oxidation reaction (WOR) conditions at pH = 1, blue films were observed to deposit on the electrode surfaces for all of the complexes, without the detection of oxygen. For chemically driven WORs, three oxidants with different overpotentials and electron-transfer kinetics led to very different behaviors. [Ru(bpy)3]3+ was shown to slowly oxidize the ligands without generating oxygen at pH = 3.7. With NaIO4 as the oxidant at neutral pH, oxygen generation was observed, but ligand oxidation was also seen for the complexes with electron-donating substituents such as –OMe or –OH groups. With Ce4+ as the oxidant at pH = 1, a competition between water oxidation and ligand decomposition existed; less ligand decomposition was observed for catalysts that are more active for WOR. These results indicate the intricate nature of molecule water-oxidation catalysts and their complex behaviors that are highly sensitive to water-oxidation conditions.
Co-reporter:Dr. Michaël Carboni;Zekai Lin;Carter W. Abney;Teng Zhang ;Dr. Wenbin Lin
Chemistry - A European Journal 2014 Volume 20( Issue 46) pp:14965-14970
Publication Date(Web):
DOI:10.1002/chem.201405194
Abstract
Two metal–organic frameworks (MOFs) with Zr–oxo secondary building units (SBUs) were prepared by using p,p′-terphenyldicarboxylate (TPDC) bridging ligands pre-functionalized with orthogonal succinic acid (MOF-1) and maleic acid groups (MOF-2). Single-crystal X-ray structure analysis of MOF-1 provides the first direct evidence for eight-connected SBUs in UiO-type MOFs. In contrast, MOF-2 contains twelve-connected SBUs as seen in the traditional UiO MOF topology. These structural assignments were confirmed by extended X-ray absorption fine structure (EXAFS) analysis. The highly porous MOF-1 is an excellent fluorescence sensor for metal ions with the detection limit of <0.5 ppb for Mn2+and three to four orders of magnitude greater sensitivity for metal ions than previously reported luminescent MOFs.
Co-reporter:Cheng Wang ; Demin Liu
Journal of the American Chemical Society 2013 Volume 135(Issue 36) pp:13222-13234
Publication Date(Web):August 14, 2013
DOI:10.1021/ja308229p
Metal–organic frameworks (MOFs), also known as coordination polymers, represent an interesting class of crystalline molecular materials that are synthesized by combining metal-connecting points and bridging ligands. The modular nature of and mild conditions for MOF synthesis have permitted the rational structural design of numerous MOFs and the incorporation of various functionalities via constituent building blocks. The resulting designer MOFs have shown promise for applications in a number of areas, including gas storage/separation, nonlinear optics/ferroelectricity, catalysis, energy conversion/storage, chemical sensing, biomedical imaging, and drug delivery. The structure–property relationships of MOFs can also be readily established by taking advantage of the knowledge of their detailed atomic structures, which enables fine-tuning of their functionalities for desired applications. Through the combination of molecular synthesis and crystal engineering, MOFs thus present an unprecedented opportunity for the rational and precise design of functional materials.
Co-reporter:Teng Zhang ; Cheng Wang ; Shubin Liu ; Jin-Liang Wang
Journal of the American Chemical Society 2013 Volume 136(Issue 1) pp:273-281
Publication Date(Web):December 10, 2013
DOI:10.1021/ja409267p
Simply mixing a Cu(II) salt and 6,6′-dihydroxy-2,2′-bipyridine (H2L) in a basic aqueous solution afforded a highly active water oxidation catalyst (WOC). Cyclic voltammetry of the solution at pH = 12–14 shows irreversible catalytic current with an onset potential of ∼0.8 V versus NHE. Catalytic oxygen evolution takes place in controlled potential electrolysis at a relatively low overpotential of 640 mV. Experimental and computational studies suggest that the L ligand participates in electron transfer processes to facilitate the oxidation of the Cu center to lead to an active WOC with low overpotential, akin to the use of the tyrosine radical by Photosystem II to oxidize the CaMn4 center for water oxidation.
Co-reporter:Caleb A. Kent, Demin Liu, Akitaka Ito, Teng Zhang, M. Kyle Brennaman, Thomas J. Meyer and Wenbin Lin
Journal of Materials Chemistry A 2013 vol. 1(Issue 47) pp:14982-14989
Publication Date(Web):23 Oct 2013
DOI:10.1039/C3TA14009A
Two non-porous metal–organic frameworks (MOFs) with caged Ru(bpy)32+ chromophores, [Ru(bpy)3][Zn2(C2O4)3] (1) and [Ru(bpy)3][NaAl(C2O4)3] (2), were synthesized and characterized. Their emission properties were studied by both steady-state and time-resolved luminescence measurements. Air-free microcrystals of 1 and 2 exhibit long-lived triplet metal-to-ligand charge transfer (3MLCT) excited states with lifetimes of 760 and 1305 ns, respectively. Lifetimes are significantly shortened (to 92 ns for 1 and 144 ns for 2) by trapping of trace amounts of oxygen in the non-porous MOFs, presumably due to amplified luminescence quenching of Ru(bpy)32+*. Following MLCT excitation, Ru(bpy)32+*/Ru(bpy)32+ energy transfer migration in 1 and 2 results in efficient quenching of Ru(bpy)32+* by Os(bpy)32+ added as an energy transfer trap at doping levels of 0.2–1.0%. A kinetic analysis indicates that the three-dimensional chromophore connectivity in 1 and 2 provides a network for rapid excited state energy transfer migration among Ru(bpy)32+ units, ultimately, finding an Os(bpy)32+ trap site. These crystalline frameworks with caged chromophores have proven to be ideal systems for studying light harvesting processes in artificial supramolecular systems.
Co-reporter:Michaël Carboni, Carter W. Abney, Kathryn M. L. Taylor-Pashow, Juan L. Vivero-Escoto, and Wenbin Lin
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 43) pp:15187-15197
Publication Date(Web):2017-2-22
DOI:10.1021/ie402646r
A series of functionalized mesoporous carbon (MC) materials were prepared by covalent grafting with amidoxime, carboxyl, and phosphoryl functional groups and screened for uranium (U) sorption from aqueous media. The MC materials were characterized by nitrogen adsorption measurements and thermogravimetric analysis and investigated for U(VI) extraction from both acidic water (pH 4) and artificial seawater (pH 8.2). Under both conditions, a phosphoric acid-functionalized MC exhibited the highest U(VI) sorption, with a maximum sorption capacity of 97 mg of U(VI)/(g of sorbent) in acidic water and 67 mg of U(VI)/(g of sorbent) in artificial seawater. The effects of pH on U(VI) sorption, sorption kinetics, and sorption isotherms were obtained for the phosphoric acid-functionalized MC. Quantitative U(VI) removal from U(VI)-loaded sorbents was achieved by washing with HCl at concentrations higher than 0.01 M. These results indicate that functionalized MC provides a promising platform for the development of novel sorbents for efficient U(VI) extraction.
Co-reporter:Carter W. Abney, Shubin Liu, and Wenbin Lin
The Journal of Physical Chemistry A 2013 Volume 117(Issue 45) pp:11558-11565
Publication Date(Web):October 18, 2013
DOI:10.1021/jp408460x
Amidoxime functionalized sorbents have shown great promise in extracting uranium from seawater, though the rationale for this affinity is not apparent. To enhance binding by amidoxime and to develop more selective sorbents, a detailed understanding of the electronic structure is necessary. This study investigates the electronic effects of amidoximate ligands bound to the uranyl cation, UO22+. Density functional theory calculations have been performed on a series of uranyl–amidoximate derivatives to investigate their structural, electronic, and thermochemical properties. The computational findings are in good agreement with available experimental data, with average error in bond length below 0.07 Å for all systems. Binding strength was observed to be directly related to electron donation, as evidenced by the plot of log(K/K0) vs the Hammett constant (σpara) of the substituent adjacent to the oximate function. From this observation, we propose and investigate two new imidazole-derived oximes, both of which possess greater binding strength than amidoximate derivatives.
Co-reporter:Joseph Della Rocca, Michael E. Werner, Stephanie A. Kramer, Rachel C. Huxford-Phillips, Rohit Sukumar, Natalie D. Cummings, Juan L. Vivero-Escoto, Andrew Z. Wang, Wenbin Lin
Nanomedicine: Nanotechnology, Biology and Medicine (January 2015) Volume 11(Issue 1) pp:31-38
Publication Date(Web):1 January 2015
DOI:10.1016/j.nano.2014.07.004
Chemoradiotherapy is a well-established treatment paradigm in oncology. There has been strong interest in identifying strategies to further improve its therapeutic index. An innovative strategy is to utilize nanoparticle (NP) chemotherapeutics in chemoradiation. Since the most commonly utilized chemotherapeutic with radiotherapy is cisplatin, the development of an NP cisplatin for chemoradiotherapy has the highest potential impact on this treatment. Here, we report the development of an NP comprised of polysilsesquioxane (PSQ) polymer crosslinked by a cisplatin prodrug (Cisplatin-PSQ) and its utilization in chemoradiotherapy using non-small cell lung cancer as a disease model. Cisplatin-PSQ NP has an exceptionally high loading of cisplatin. Cisplatin-PSQ NPs were evaluated in chemoradiotherapy in vitro and in vivo. They demonstrated significantly higher therapeutic efficacy when compared to cisplatin. These results suggest that the Cisplatin-PSQ NP holds potential for clinical translation in chemoradiotherapy.From the Clinical EditorThese authors present an innovative strategy utilizing the presence of platinum in nanoparticle chemotherapeutics for chemoradiation, demonstrating its efficacy in a non-small cell lung cancer model.Cisplatin is the most commonly utilized chemotherapeutic in chemoradiotherapy for cancer. Because of its importance, there has been strong interest in identifying strategies to further improve the therapeutic index of cisplatin-based chemoradiotherapy. One approach is to develop and utilize nanoparticle cisplatin. In this study, we engineered a novel nanoparticle cisplatin (Cisplatin-PSQ NP). Cisplatin-PSQ NP has an exceptionally high loading of cisplatin. We demonstrated that Cisplatin-PSQ NP is more effective than small molecule cisplatin using mouse models of non-small cell lung cancer. Our results suggest that Cisplatin-PSQ NP holds high potential to further improve cancer chemoradiotherapy.Download high-res image (105KB)Download full-size image
Co-reporter:Chunbai He; Christopher Poon; Christina Chan; S. Diane Yamada
Journal of the American Chemical Society () pp:
Publication Date(Web):April 18, 2016
DOI:10.1021/jacs.6b02486
Drug resistance impedes the successful treatment of many types of cancers, especially ovarian cancer (OCa). To counter this problem, we developed novel long-circulating, self-assembled core–shell nanoscale coordination polymer (NCP) nanoparticles that efficiently deliver multiple therapeutics with different mechanisms of action to enhance synergistic therapeutic effects. These NCP particles contain high payloads of chemotherapeutics cisplatin or cisplatin plus gemcitabine in the core and pooled siRNAs that target multidrug resistant (MDR) genes in the shell. The NCP particles possess efficient endosomal escape via a novel carbon dioxide release mechanism without compromising the neutral surface charge required for long blood circulation and effectively downregulate MDR gene expression in vivo to enhance chemotherapeutic efficacy by several orders of magnitude. Even at low doses, intraperitoneal injections of nanoparticles led to effective and long-lasting tumor regression/eradication in subcutaneous and intraperitoneal xenograft mouse models of cisplatin-resistant OCa. By silencing MDR genes in tumors, self-assembled core–shell nanoparticles promise a more effective chemotherapeutic treatment for many challenging cancers.
Co-reporter:Chunbai He ; Kuangda Lu
Journal of the American Chemical Society () pp:
Publication Date(Web):August 19, 2014
DOI:10.1021/ja507333c
Real-time measurement of intracellular pH in live cells is of great importance for understanding physiological/pathological processes and developing intracellular drug delivery systems. We report here the first use of nanoscale metal–organic frameworks (NMOFs) for intracellular pH sensing in live cells. Fluorescein isothiocyanate (FITC) was covalently conjugated to a UiO NMOF to afford F-UiO NMOFs with exceptionally high FITC loadings, efficient fluorescence, and excellent ratiometric pH-sensing properties. Upon rapid and efficient endocytosis, F-UiO remained structurally intact inside endosomes. Live cell imaging studies revealed endo- and exocytosis of F-UiO and endosome acidification in real time. Fluorescently labeled NMOFs thus represent a new class of nanosensors for intracellular pH sensing and provide an excellent tool for studying NMOF–cell interactions.
Co-reporter:Xin-Bao Han ; Zhi-Ming Zhang ; Teng Zhang ; Yang-Guang Li ; Wenbin Lin ; Wansheng You ; Zhong-Min Su ;En-Bo Wang
Journal of the American Chemical Society () pp:
Publication Date(Web):March 24, 2014
DOI:10.1021/ja412886e
A series of all-inorganic, abundant-metal-based, high-nuclearity cobalt–phosphate (Co–Pi) molecular catalysts [{Co4(OH)3(PO4)}4(SiW9O34)4]32– (1), [{Co4(OH)3(PO4)}4(GeW9O34)4]32– (2), [{Co4(OH)3(PO4)}4(PW9O34)4]28– (3), and [{Co4(OH)3(PO4)}4(AsW9O34)4]28– (4) were synthesized and shown to be highly effective at photocatalytic water oxidation. The {Co16(PO4)4} cluster contains a Co4O4 cubane which is structurally analogous to the [Mn3CaO4] core of the oxygen-evolving complex (OEC) in photosystem II (PSII). Compounds 1–4 were shown to be the first POM-based Co–Pi-cluster molecular catalysts for visible light-driven water oxidation, thus serving as a functional model of the OEC in PSII. The systematic synthesis of four isostructural analogues allowed for investigating the influence of different heteroatoms in the POM ligands on the photocatalytic activities of these Co–Pi cluster WOCs. Further, the POM-based photocatalysts readily recrystallized from the photocatalytic reaction systems with the polyoxoanion structures unchanged, which together with the laser flash photolysis, dynamic light-scattering, 31P NMR, UV–vis absorption, POM extraction, and ICP-MS analysis results collectively confirmed that compounds 1–4 maintain their structural integrity under the photocatalytic conditions. This study provides not only a valuable molecular model of the “Co–Pi” catalysts with a well-defined structure but also an unprecedented opportunity to fine-tune high-nuclearity POM clusters for visible light-driven water splitting.
Co-reporter:Caleb A. Kent, Demin Liu, Akitaka Ito, Teng Zhang, M. Kyle Brennaman, Thomas J. Meyer and Wenbin Lin
Journal of Materials Chemistry A 2013 - vol. 1(Issue 47) pp:NaN14989-14989
Publication Date(Web):2013/10/23
DOI:10.1039/C3TA14009A
Two non-porous metal–organic frameworks (MOFs) with caged Ru(bpy)32+ chromophores, [Ru(bpy)3][Zn2(C2O4)3] (1) and [Ru(bpy)3][NaAl(C2O4)3] (2), were synthesized and characterized. Their emission properties were studied by both steady-state and time-resolved luminescence measurements. Air-free microcrystals of 1 and 2 exhibit long-lived triplet metal-to-ligand charge transfer (3MLCT) excited states with lifetimes of 760 and 1305 ns, respectively. Lifetimes are significantly shortened (to 92 ns for 1 and 144 ns for 2) by trapping of trace amounts of oxygen in the non-porous MOFs, presumably due to amplified luminescence quenching of Ru(bpy)32+*. Following MLCT excitation, Ru(bpy)32+*/Ru(bpy)32+ energy transfer migration in 1 and 2 results in efficient quenching of Ru(bpy)32+* by Os(bpy)32+ added as an energy transfer trap at doping levels of 0.2–1.0%. A kinetic analysis indicates that the three-dimensional chromophore connectivity in 1 and 2 provides a network for rapid excited state energy transfer migration among Ru(bpy)32+ units, ultimately, finding an Os(bpy)32+ trap site. These crystalline frameworks with caged chromophores have proven to be ideal systems for studying light harvesting processes in artificial supramolecular systems.
Co-reporter:Chao Zhang, Bing An, Ling Yang, Binbin Wu, Wei Shi, Yu-Cheng Wang, La-Sheng Long, Cheng Wang and Wenbin Lin
Journal of Materials Chemistry A 2016 - vol. 4(Issue 12) pp:NaN4463-4463
Publication Date(Web):2016/02/16
DOI:10.1039/C6TA00768F
We report the first synthesis of sulfurated porous carbon materials with well-defined morphologies and uniform N/S distributions via pyrolysis of zeolitic imidazolate frameworks loaded with sulfur-containing molecules. The optimized sulfurated catalyst demonstrates excellent electrocatalytic activity for the oxygen reduction reaction (ORR) in both acid and alkaline media. The sulfurization process under optimized conditions can lower the ORR over-potential by ca. 170 mV at 3 mA cm−2, giving a non-precious metal catalyst with an onset ORR potential of 0.90 V (vs. RHE, similarly hereinafter)/half-wave potential of 0.78 V in 0.1 M HClO4 and an onset ORR potential of 0.98 V/half-wave potential of 0.88 V in 0.1 M KOH. Furthermore, the S-doped porous carbon materials perform better in the long-term durability test than the non-S-doped samples and standard commercially available Pt/C. We also discuss different sulfuration methods for the ZIF system, morphologies of pyrolyzed samples, and catalytically active sites.
Co-reporter:Teng Zhang and Wenbin Lin
Chemical Society Reviews 2014 - vol. 43(Issue 16) pp:NaN5993-5993
Publication Date(Web):2014/04/28
DOI:10.1039/C4CS00103F
Solar energy is an alternative, sustainable energy source for mankind. Finding a convenient way to convert sunlight energy into chemical energy is a key step towards realizing large-scale solar energy utilization. Owing to their structural regularity and synthetic tunability, metal–organic frameworks (MOFs) provide an interesting platform to hierarchically organize light-harvesting antennae and catalytic centers to achieve solar energy conversion. Such photo-driven catalytic processes not only play a critical role in the solar to chemical energy conversion scheme, but also provide a novel methodology for the synthesis of fine chemicals. In this review, we summarize the fundamental principles of energy transfer and photocatalysis and provide an overview of the latest progress in energy transfer, light-harvesting, photocatalytic proton and CO2 reduction, and water oxidation using MOFs. The applications of MOFs in organic photocatalysis and degradation of model organic pollutants are also discussed.
Co-reporter:Zhi-Ming Zhang, Xiaopin Duan, Shuang Yao, Zhishu Wang, Zekai Lin, Yang-Guang Li, La-Sheng Long, En-Bo Wang and Wenbin Lin
Chemical Science (2010-Present) 2016 - vol. 7(Issue 7) pp:NaN4229-4229
Publication Date(Web):2016/03/09
DOI:10.1039/C5SC04408A
We report the crystallization of homochiral polyoxometalate (POM) macroanions {CoSb6O4(H2O)3[Co(hmta)SbW8O31]3}15− (1, hmta = hexamethylenetetramine) via the counter cation-mediated chiral symmetry breaking and asymmetric autocatalytic processes. In the presence of low Co2+ concentrations both Δ- and Λ-enantiomers of 1 formed in the reaction, crystallizing into the racemic crystal rac-1. At a high Co2+ concentration, the polyoxoanion enantiomers showed a high level of chiral recognition via H-bonding interactions to crystallize into enantiopure crystals of Δ- or Λ-[Co(H2O)6{CoSb6O4(H2O)3[Co(hmta)SbW8O31]3}]13−. During crystallization, a microscale symmetry-breaking event and a nonlinear asymmetric autocatalysis process make the enantiomers crystallize in different batches, which provides an opportunity to isolate the homochiral bulk materials. The defined structures of the racemic and homochiral crystals thus provide a molecular-level illustration that H-bonding interactions are responsible for such high-level chiral recognition, in a process similar to the supramolecular chirality frequently observed in biology. These POM macroanions showed a high cytotoxicity against various cancer cells, particularly ovarian cancer cells. The antitumor activity of these compounds resulted at least in part from the activation of the apoptotic pathways, as shown by the flow cytometry, Annexin V staining, DNA ladder, and TUNEL assay, likely by blocking the cell cycle and complexing with proteins in cells. The POM macroanions reported herein provide promising and novel antitumor agents for the potential treatment of various cancers.
Co-reporter:Xinping Lin, Yahui Hong, Chao Zhang, Ruiyun Huang, Cheng Wang and Wenbin Lin
Chemical Communications 2015 - vol. 51(Issue 95) pp:NaN16999-16999
Publication Date(Web):2015/09/30
DOI:10.1039/C5CC06453H
The 2,2′-bipyridyl moieties lining the channels of two designer metal–organic frameworks (MOFs), UiO-bpydc and Eu-bpydc (bpydc is 2,2′-bipyridine 5,5′-dicarboxylic acid), recognize and pre-concentrate metal ion analytes and, in the case of Eu-bpydc, transfer energy to the Eu3+ centers, to provide highly sensitive luminescence sensors for transition metal ions.
Co-reporter:C. Zhang, X. Lin, Z. Zhang, L.-S. Long, C. Wang and W. Lin
Chemical Communications 2014 - vol. 50(Issue 78) pp:NaN11594-11594
Publication Date(Web):2014/08/12
DOI:10.1039/C4CC03487B
A novel organic–inorganic hybrid monocapped/bicapped Keggin structure [CoII(bpy)3]6(H2bpy)[(CoIIbpy)2(PMo8VIMo4VO40)]3 [(CoIIbpy)(PMo8VIMo4VO40)]·16H2O (bpy = 2,2′-bipyridine) was synthesized and shown to be an efficient visible light-driven catalyst for water oxidation.
Co-reporter:Takahiro Sawano, Pengfei Ji, Alexandra R. McIsaac, Zekai Lin, Carter W. Abney and Wenbin Lin
Chemical Science (2010-Present) 2015 - vol. 6(Issue 12) pp:NaN7168-7168
Publication Date(Web):2015/09/14
DOI:10.1039/C5SC02100F
We have designed the first chiral diene-based metal–organic framework (MOF), E2-MOF, and postsynthetically metalated E2-MOF with Rh(I) complexes to afford highly active and enantioselective single-site solid catalysts for C–C bond formation reactions. Treatment of E2-MOF with [RhCl(C2H4)2]2 led to a highly enantioselective catalyst for 1,4-additions of arylboronic acids to α,β-unsaturated ketones, whereas treatment of E2-MOF with Rh(acac)(C2H4)2 afforded a highly efficient catalyst for the asymmetric 1,2-additions of arylboronic acids to aldimines. Interestingly, E2-MOF·Rh(acac) showed higher activity and enantioselectivity than the homogeneous control catalyst, likely due to the formation of a true single-site catalyst in the MOF. E2-MOF·Rh(acac) was also successfully recycled and reused at least seven times without loss of yield and enantioselectivity.
Co-reporter:Demin Liu, Chunbai He, Christopher Poon and Wenbin Lin
Journal of Materials Chemistry A 2014 - vol. 2(Issue 46) pp:NaN8255-8255
Publication Date(Web):2014/10/08
DOI:10.1039/C4TB00751D
Nanoscale coordination polymers (NCPs) are self-assembled from metal ions and organic bridging ligands. The tunable compositions, sizes, and shapes; high drug loadings; ease of surface modification; and intrinsic biodegradability make NCPs great candidates for nanomedicine applications. Here we report the self-assembly of a Mn-bisphosphonate NCP that carries exceptionally high loadings of zoledronate (63 ± 5 wt%) and Mn2+ ions (13 ± 4 wt%) for potential cancer therapy and magnetic resonance imaging, respectively. The Mn-bisphosphonate NCP was further coated with lipid and pegylated to control the drug release kinetics and functionalized with a targeting group (anisamide) to endow specificity to cancer cells, leading to significantly enhanced cytotoxicity against human breast and pancreatic cancer cells. In vitro MR imaging studies demonstrated the efficacy of the Mn-bisphosphonate NCP as an effective T1 contrast agent and confirmed the targeting capability of anisamide-functionalized NCP. Multifunctional NCPs thus present an excellent platform for designing theranostic nanomaterials for a wide range of biomedical applications.
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