Xiaohong Li

Soochow University (PRC), Wu-hsien, Jiangsu Sheng, China

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Publications (42)207.65 Total impact

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    ABSTRACT: By introducing CO2 as the oxygen source during the arcing process, a new isomer of Sc2O@C82, Sc2O@C3v(8)-C82, previously investigated only by computational studies, was discovered and characterized by mass spectrometry, UV-vis-NIR absorption spectroscopy, cyclic voltammetry, (45)Sc NMR, density functional theory (DFT) calculations, and single-crystal X-ray diffraction. The crystallographic analysis unambiguously elucidated that the cage symmetry was assigned to C3v(8) and suggests that Sc2O cluster is disordered inside the cage. The comparative studies of crystallographic data further reveal that the Sc1-O-Sc2 angle is in the range of 131.0-148.9°, much larger than that of the Sc2S@C3v(8)-C82, demonstrating a significant flexibility of dimetallic clusters inside the cages. The electrochemical studies show that the electrochemical gap of Sc2O@C3v(8)-C82 is 1.71 eV, the largest among those of the oxide cluster fullerenes (OCFs) reported so far, well correlated with its rich abundance in the reaction mixture of OCF synthesis. Moreover, the comparative electrochemical studies suggest that both the dimetallic clusters and the cage structures have major influences on the electronic structures of the cluster fullerenes. Computational studies show that the cluster can rotate and change the Sc-O-Sc angle easily at rather low temperature.
    Full-text · Article · Feb 2016 · Inorganic Chemistry
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    ABSTRACT: To achieve high refractive index polymers (HRIPs), we report here the design and synthesis of four fullerene polyesters (P1-P4), based on the conjunction effect from the high refractive index polyester backbones and pendent fullerene side chains. At sodium D line (589 nm), the refractive indices of the fullerene polyesters are all higher than 1.80, the used believed upper limitation of intrinsic organic polymers. To achieve precise pendent fullerene structure, these polyesters were synthesized via condensation polymerization by a fullerene diol with different aromatic diacyl chlorides, where the diacyl chlorides with high molar refraction increment value moiety were selected by molecular tailoring according to Lorentz-Lorenz equation. The fullerene polyesters are characterized by gel permeation chromatography (GPC), ultraviolet-visible (UV-vis) spectroscopy, and the molecular weights are obtained by a quantitative NMR technique with end-group estimation. The formation of fullerene polyesters is also proved by the 1H DOSY NMR results. These fullerene polyesters have good solubility in some common organic solvents, good thermal stability up to 320°C, and film forming ability. All these films have good adhesion to glass sheets with relatively good hardness. Among them, the thiophene-containing fullerene polyesters (P1) has the best optical properties, with the highest refractive index value (1.86 at 589 nm), one of the highest value for intrinsic organic polymers, and the highest Abbe number (27.9).
    No preview · Article · Nov 2015 · Macromolecules
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    ABSTRACT: A new oxide cluster fullerene, Sc2O@C2v(5)-C80, has been isolated and characterized by mass spectrometry, UV-vis-NIR absorption spectroscopy, cyclic voltammetry, (45)Sc NMR, DFT calculations, and single crystal X-ray diffraction. The crystallographic analysis unambiguously elucidated that the cage symmetry was assigned to C2v(5)-C80 and suggests that the Sc2O cluster is ordered inside the cage. The crystallographic data further reveals that the Sc1-O-Sc2 angle is much larger than that found in Sc2O@Td(19151)-C76 but almost comparable to that in Sc2O@Cs(6)-C82, suggesting that the endohedral Sc2O unit is flexible and can display large variation in the Sc-O-Sc angle, which depends on the size and shape of the cage. Computational studies show that there is a formal transfer of four electrons from the Sc2O unit to the C80 cage, i.e., (Sc2O)(4+)@(C80)(4-), and the HOMO and LUMO are mainly localized on the C80 framework. Moreover, thermal and entropic effects are seen to be relevant in the isomer selection. Comparative studies between the recently reported Sc2C2@C2v(5)-C80 and Sc2O@C2v(5)-C80 reveal that, despite their close structural resemblance, subtle differences exist on the crystal structures, and the clusters exert notable impact on their spectroscopic properties as well as interactions between the clusters and corresponding cages.
    No preview · Article · Sep 2015 · Inorganic Chemistry
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    ABSTRACT: The radical polymerization of styrene was investigated in the presence of five diaryl diselenide compounds with different substitution groups on the benzene ring under visible light irradiation. It showed that bis(2,6-dimethylphenyl) diselenide (DmXDS) with two methyl groups on every benzene ring was the most efficient mediator for preparing polymers with a predetermined molecular weight and narrow molecular weight distribution. The reasons were analyzed through a quantum calculation method. The polymerization behavior of styrene in the presence of DmXDS was further investigated in depth. The results showed a typical living radical polymerization process. Polymers retaining the selenide structures at both the α- and ω-ends were verified by NMR and MALDI-TOF. Such end capped selenide groups could be transformed into terminal vinyl groups with a high efficiency under oxidative conditions, which offers a route to prepare "macromonomers" with a narrow molecular weight distribution.
    No preview · Article · Sep 2015
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    ABSTRACT: PurposePlexiform neurofibromas (pNF) are pathognomonic nerve and soft tissue tumors of neurofibromatosis type I (NF1), which are highly resistant to conventional chemotherapy and associated with significant morbidity/mortality. Disruption of aberrant SCF/c-Kit signaling emanating from the pNF microenvironment induced the first ever objective therapeutic responses in a recent phase 2 trial. Sunitinib malate is a potent, highly selective RTK inhibitor with activity against c-Kit, PDGFR, and VEGFR, which have also been implicated in the pathogenesis of these lesions. Here, we evaluate the efficacy of sunitinib malate in a preclinical Krox20;Nf1flox/− pNF murine model.Experimental DesignProliferation, β-hexosaminidase release (degranulation), and Erk1/2 phosphorylation were assessed in sunitinib treated Nf1+/− mast cells and fibroblasts, respectively. Krox20;Nf1flox/- mice with established pNF were treated sunitinib or PBS-vehicle control for a duration of 12 weeks. pNF metabolic activity was monitored by serial [18F]DG-PET/CT imaging.ResultsSunitinib suppressed multiple in vitro gain-in-functions of Nf1+/− mast cells and fibroblasts and attenuated Erk1/2 phosphorylation. Sunitinib treated Krox20;Nf1flox/− mice exhibited significant reductions in pNF size, tumor number, and FDG uptake compared to control mice. Histopathology revealed reduced tumor cellularity and infiltrating mast cells, markedly diminished collagen deposition, and increased cellular apoptosis in sunitinib treated pNF.Conclusions Collectively, these results demonstrate the efficacy of sunitinib in reducing tumor burden in Krox20;Nf1flox/− mice. These preclinical findings demonstrate the utility of inhibiting multiple RTKs in pNF and provide insights into the design of future clinical trials. Pediatr Blood Cancer © 2015 Wiley Periodicals, Inc.
    Full-text · Article · Sep 2015 · Pediatric Blood & Cancer
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    ABSTRACT: A new cluster fullerene, Sc2 O@Td (19151)-C76 , has been isolated and characterized by mass spectrometry, UV/Vis/NIR absorption, (45) Sc NMR spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction. The crystallographic analysis unambiguously assigned the cage structure as Td (19151)-C76 , which is the first tetrahedral fullerene cage characterized by single-crystal X-ray diffraction. This study also demonstrated that the Sc2 O cluster has a much smaller ScOSc angle than that of Sc2 O@Cs (6)-C82 and the Sc2 O unit is fully ordered inside the Td (19151)-C76 cage. Computational studies further revealed that the cluster motion of the Sc2 O is more restrained in the Td (19151)-C76 cage than that in the Cs (6)-C82 cage. These results suggest that cage size affects not only the shapes but also the cluster motion inside fullerene cages. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    No preview · Article · Jun 2015 · Chemistry - A European Journal
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    ABSTRACT: m-Phthalic diamide-linked zinc bisporphyrinates have been developed as chirality probes for monoamines. They are capable of determining the absolute configuration of monoamines and distinguishing between alkyl and aryl substituents of chiral monoamines. Our studies suggest steric interactions play critical roles in the molecular recognition process.
    Full-text · Article · Jun 2015 · Dalton Transactions
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    ABSTRACT: Despite the high prevalence and significant morbidity of spinal anomalies in neurofibromatosis type 1 (NF1), the pathogenesis of these defects remains largely unknown. Here, we present two murine models: Nf1flox/-;PeriCre and Nf1flox/-;Col.2.3Cre mice, which recapitulate spinal deformities seen in the human disease. Dynamic histomorphometry and microtomographic studies show recalcitrant bone remodeling and distorted bone microarchitecture within the vertebral spine of Nf1flox/-;PeriCre and Nf1flox/-;Col2.3Cre mice, with analogous histological features present in a human patient with dystrophic scoliosis. Intriguingly, 36-60% of Nf1flox/-;PeriCre and Nf1flox/-;Col2.3Cre mice exhibit segmental vertebral fusion anomalies with boney obliteration of the intervertebral disc (IVD). While analogous findings have not yet been reported in the NF1 patient population, we herein present two case reports of IVD defects and interarticular vertebral fusion in patients with NF1. Collectively, these data provide novel insights regarding the pathophysiology of dystrophic spinal anomalies in NF1, and provide impetus for future radiographic analyses of larger patient cohorts to determine whether IVD and vertebral fusion defects may have been previously overlooked or underreported in the NF1 patient population.
    Full-text · Article · Mar 2015 · PLoS ONE
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    Hongmei Zhang · Chenglong Xu · Jie Liu · Xiaohong Li · Lin Guo · Xinming Li
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    ABSTRACT: We report the design and synthesis of a novel probe (1) for ALP assay by incorporating a self-immolative linker between phosphate moiety and resorufin. Because of its good biocompatibility and rapid cell internalization, this probe also exhibited great potential for real-time monitoring of endogenous ALP activity in living cells.
    Full-text · Article · Mar 2015 · Chemical Communications
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    ABSTRACT: Monomer-activating effect imposed by hydrogen bonding has been long acknowledged, however, the in-depth understanding was still lack. In this work, for the first time, the monomer-activating effect was elucidated with 2-vinyl pyridine (2VP) as model monomer and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as hydrogen bonding donor (solvent). A strong hydrogen bonding between HFIP and 2VP was revealed by careful 1H NMR analysis and computer simulations. Upon this solid hydrogen bonding, 2VP underwent a well-controlled radical polymerization with improved control over molecular weight in contrast to those under non-hydrogen bonding environment. The well-controlled polymerization manner was ascribed to the electron induction effect of monomer molecules under hydrogen bonding interaction, i.e., the electron redistribution of the monomer's vinyl double bonds, activating the monomers. The hydrogen bonding interactions between HFIP and growing radicals or HFIP and terminal monomer units of dormant polymeric species might also contribute to the good control. The unprecedented explanation of hydrogen bonding promoting controlled radical polymerization or monomer-activating effect was testified for other monomers, and some reasonable discussions were made.
    Preview · Article · Feb 2015 · Polymer Chemistry
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    ABSTRACT: Directed by increasing the density of coordination sites (DOCS) to increase the stability of assemblies, discrete 2D ring-in-rings and 3D sphere-in-sphere were designed and self-assembled by one tetratopic pyridyl-based ligand with 180° diplatinum(II) acceptors and naked Pd(II), respectively. The high DOCS resulted by multitopic ligand provided more geometric constraints to form discrete structures with high stability. Compared to reported supramolecular hexagons and polyhedra by ditotpic ligands, the self-assembly of such giant architectures using multitopic ligands with all rigid backbone emphasized the structural integrity with precise preorganization of entire architecture, and required elaborate synthetic operations for ligand preparation. In-depth structural characterization was conducted to support desired structures, including multinuclear NMR (1H, 31P, and 13C) analysis, 2D NMR spectroscopy (COSY and NOESY), diffusionordered NMR spectroscopy (DOSY), multidimensional mass spectrometry, TEM and AFM. Furthermore, a quantitative definition of DOCS was proposed to compare 2D and 3D structures and correlate the DOCS and stability of assemblies in a quantitative manner. Finally, ring-in-rings in DMSO or DMF could undergo hierarchical self-assembly into the ordered nanostructures and generated translucent supramolecular metallogels.
    Full-text · Article · Jan 2015 · Journal of the American Chemical Society
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    ABSTRACT: Fullerene-based liquid crystalline materials have both the excellent optical and electrical properties of fullerene and the self-organization and external-field-responsive properties of liquid crystals (LCs). Herein, we demonstrate a new family of thermotropic [60]fullerene supramolecular LCs with hierarchical structures. The [60]fullerene dyads undergo self-organization driven by π–π interactions to form triple-layer two-dimensional (2D) fullerene crystals sandwiched between layers of alkyl chains. The lamellar packing of 2D crystals gives rise to the formation of supramolecular LCs. This design strategy should be applicable to other molecules and lead to an enlarged family of 2D crystals and supramolecular liquid crystals.
    Full-text · Article · Jan 2015 · Angewandte Chemie
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    ABSTRACT: Fullerene-based liquid crystalline materials have both the excellent optical and electrical properties of fullerene and the self-organization and external-field-responsive properties of liquid crystals (LCs). Herein, we demonstrate a new family of thermotropic [60]fullerene supramolecular LCs with hierarchical structures. The [60]fullerene dyads undergo self-organization driven by π–π interactions to form triple-layer two-dimensional (2D) fullerene crystals sandwiched between layers of alkyl chains. The lamellar packing of 2D crystals gives rise to the formation of supramolecular LCs. This design strategy should be applicable to other molecules and lead to an enlarged family of 2D crystals and supramolecular liquid crystals.
    Full-text · Article · Jan 2015 · Angewandte Chemie International Edition
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    ABSTRACT: An extensive family of oxide cluster fullerenes (OCFs) Sc2O@C2n (n = 35–47) has been facilely produced for the first time by introducing CO2 as the oxygen source. Among this family, Sc2O@C70 was identified as the smallest OCF and therefore isolated and characterized by mass spectrometry, 45Sc nuclear magnetic resonance, UV–vis–near-infrared absorption spectroscopy, cyclic voltammetry, and density functional theory calculations. The combined experimental and computational studies reveal a non-isolated pentagon rule isomer Sc2O@C2(7892)–C70 with reversible oxidative behavior and lower bandgap relative to that of Sc2S@C2(7892)–C70, demonstrating a typical example of unexplored OCF and underlining its cluster-dependent electronic properties.
    No preview · Article · Dec 2014 · The Journal of Physical Chemistry C
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    ABSTRACT: We reported the generation of a novel self-assembled prodrug of platinum (Pt) from short peptide derivative, a substrate of phosphatase for dephosphorylation reaction, and Pt(IV) complex, which could undergo supramolecular self-assemblies with the presence of alkaline phosphatase, and perform controlled release of Pt(II) drug under reductive condition of tumor cell. This self-assembled prodrug showed significant antitumor growth effects on a breast cancer xenograft model based on 4T1 cells in vivo, but much lower toxicity towards kidney, liver, spleen and other major organs in mice than the free drug of cisplatin. Such improved antitumor efficacy could be ascribed to the localized and sustained release of Pt(II) anticancer drug from the supramolecular self-assemblies of the Pt(IV) prodrug which was triggered by phosphatases in tumor site.
    No preview · Article · Oct 2014
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    ABSTRACT: Using a series of tritopic 2,2':6',2"-terpyridine (tpy) ligands constructed on adamantane, three discrete 3D metallo-supramolecular architectures were assembled, i.e., trigonal bipyramidal, tetrahedron and cube. The self-assembly used tritopic ligands as corner directing units and metal ions as glue units at the edge. The angles of the linkers between adamantane and tpy head play a critical role in guiding the assembled structures, which have the general formula of M3nL2n, where M denotes metal ion and L denotes ligand. All complexes were fully characterized by 1H, 13C NMR, diffusion-ordered NMR spectroscopy (DOSY), ESI-MS and traveling-wave ion mobility-mass spectrometry (TWIM-MS). The binary mixtures of LA and LC, or LB and LC underwent a self-sorting process that led to the self-assembly of discrete 3D structures. The self-sorting behavior is solely based on the angles pre-coded within the arm of tritopic ligands. Moreover, kinetic study of preassembled cube and tetrahedron demonstrated a slow ligand exchange process towards a statistical mixture of hetero tetrahedrons with LA and LB.
    No preview · Article · Jun 2014 · Journal of the American Chemical Society
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    ABSTRACT: In this article, we have synthesized a polymer containing regulated azobenzene groups by one-pot multi-component polymerization (MCP) based on Passerini reaction, and investigated its self-assembly behavior and photo-induced deformation properties. We found that this molecule can form spherical structures with sizes ranging from hundreds of nanometers to several micrometers when dissolved in THF. NMR and FTIR studies indicate that there are associated hydrogen bonds among the molecules in the aggregates, which are responsible for the formation of the nanospheres. By controlling the stirring rate as the THF suspension is dropped into water, the nanospheres can be sorted according to their size. In this way, we have obtained nanospheres with relatively uniform diameter. When irradiated by UV light in the aqueous medium, the nanospheres tend to aggregate into large clusters, while in dry state they are ready to merge into island-like structures, showing a good photo-induced deformation property.
    Full-text · Article · May 2014 · Soft Matter
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    ABSTRACT: In this study, we overcame a challenge in conventional self-assembly of macrocycles by ditopic 2,2':6',2"-terpyridine (tpy) building blocks with a 120o angle between two ligating moieties, which generally produced a mixture of multiple macrocycles instead of single hexagon. Two supramolecular hexagon wreaths, [Zn9LA6] and [Zn12LB6], were designed and self-assembled by tritopic and tetratopic tpy ligands with Zn(II) ions, respectively. These multitopic ligands bearing multiple binding sites increased the total density of coordination sites and provided high geometric constraints to induce the formation of discrete structures. Such hexagon wreaths, which were constructed by simple recursion of small hexagons around the central hexagon, exhibit fractal geometry features with self-similarity at different levels. The shapes, sizes and structures were fully characterized by NMR, ESI-MS, traveling-wave ion mobility-mass spectrometry (TWIM-MS) and transmission electron microscopy (TEM). With a diameter around 5.5 nm for [Zn9LA6] and 5.8 nm for [Zn12LB6], the remarkable rigidity of these fractal architectures were supported by TWIM-MS instead of the high flexibility of macrocycles assembled by ditopic tpy ligands.
    No preview · Article · Apr 2014 · Journal of the American Chemical Society
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    ABSTRACT: We demonstrate here a novel method to synthesize poly(ethylene terephthalate)-block-poly(tetramethylene oxide) multiblock copolymers (PET-b-PTMO-b-PET)x by the one pot melt polymerization of cyclic oligo(ethylene terephthalate)s (COETs) using poly(tetramethylene oxide) (PTMO) as a macroinitiator. Two-dimensional and one-dimensional nuclear magnetic resonance (2D and 1D-NMR) techniques, including 1H–13C Heteronuclear Single Quantum Coherence (HSQC) and 1H–1H Correlation Spectroscopy (COSY), have been used to characterize and reveal the multiblock copolymer structures and absolute molecular weights. It was found that the COETs were consumed completely within 15 minutes, and the molecular weights of the block copolymers increased linearly with reaction time. Based on the polymerization kinetic studies, a two-stage polymerization mechanism is proposed: the ring-opening polymerization of COETs by a PTMO macroinitiator to PET-b-PTMO-b-PET triblock copolymers at the first stage, followed by the in situ condensation polymerization of triblock copolymers to (PET-b-PTMO-b-PET)x multiblock copolymers at the second stage. The structures of the multiblock copolymers are further characterized and confirmed by viscometry and gel permeation chromatography (GPC). These multiblock copolymers show improved thermal stability when compared to PTMO homopolymers, and double crystalline properties from PTMO and PET segments, as revealed by thermogravimetric analysis and differential scanning calorimetry, respectively.
    Preview · Article · Dec 2013
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    ABSTRACT: The polymerization of a 2,7-dibromocarbazole-containing functional monomer, 6-(2,7-dibromo-9H-carbazol-9-yl)hexyl methacrylate (DBCzMA), was successfully carried out via the reversible addition-fragmentation chain transfer (RAFT) technology. The polymerization behavior possessed the feature of “living”/controlled radical polymerization, for example, the first-order kinetics, the linear increase of the molecular weight of the polymer with the monomer conversion and relatively narrow molecular weight distribution (Mw/Mn ≤ 1.27). The amphiphilic copolymers, poly(DBCzMAm-b-NIPAMn), with different chain length of poly(DBCzMA) and poly(N-isopropylacrylamide) (PNIPAM), were successfully prepared via RAFT chain-extension reaction, using poly(DBCzMA) as the macromolecular chain transfer agent (macro-CTA) and NIPAM as the second monomer. Modification of 2,7-dibromide groups in amphiphilic copolymer poly(DBCzMA-b-NIPAM) via Suzuki coupling reaction employed 2,7-bis(4′,4′,5′,5′-tetramethyl-1′,3′,2′-dioxaborolan-2′-yl)-N−9″-heptadecanylcarbazole as the other reaction material to afford a poly(2,7-carbazole)-containing crosslinked materials. The stable and uniform core–shell fluorescent nanoparticles were successfully prepared in water. The formed fluorescent nanoparticles showed good thermoresponsive properties, which is confirmed by dynamic light scattering observation. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4021–4030
    No preview · Article · Oct 2013 · Journal of Polymer Science Part A Polymer Chemistry

Publication Stats

589 Citations
207.65 Total Impact Points

Institutions

  • 2013-2015
    • Soochow University (PRC)
      • • Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application
      • • Department of Materials Science and Engineering
      • • Department of Polymer Science and Engineering
      Wu-hsien, Jiangsu Sheng, China
  • 2007-2015
    • Indiana University School of Medicine
      • Pediatrics
      Indianapolis, Indiana, United States
  • 2006-2013
    • Indiana University-Purdue University Indianapolis
      • • Department of Pediatrics
      • • Herman B Wells Center for Pediatric Research
      Indianapolis, Indiana, United States