Developing homogeneous ion exchange membranes derived from sulfonated polyethersulfone/N-phthaloyl-chitosan for improved hydrophilic and controllable porosity

Zhixue Li,Zhun Ma,Yuting Xu,Xiaomeng Wang,Yongchao Sun,Rong Wang,Jian Wang,Xueli Gao,Jun Gao 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.8

Ion exchange membranes (IEMs) composed of sulfonated poly (ether sulfone) (SPES) and N-phthaloyl chitosan (NPHCs) were synthesized. NPHCs was employed in membrane fabrication to improve the porosity and hydrophilicity of membranes. The effect of blend ratio of sulfonation (DS) and NPHCs content on physico-chemical characteristics of home-made membranes was investigated. The morphology of prepared membranes was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and scanning electron microscopy (SEM). SEM images revealed the formation of a more porous membrane structure and smoother surface. The electrochemical and physical properties of CEMs were characterized comprising water content, contact angle, ion exchange capacity (IEC) and thermal stability. Membrane water content, surface hydrophilicity and IEC were enhanced with increase of DS and NPHCs blend ratios in casting solution. Furthermore, the diffusion coefficient was also improved slightly with increase of DS and NPHCs blend ratios in prepared membranes. Membrane potential, permselectivity, transport number and areal membrane resistance all showed decreasing trends by the increase in NPHCs blend ratio in casting solution. These results indicated that the prepared membrane has good prospective and great potential for desalination in electrodialysis applications.

Controlling Switching in Bistable [2]Catenanes by Combining Donor–Acceptor and Radical–Radical Interactions

Zhu, Zhixue,Fahrenbach, Albert C.,Li, Hao,Barnes, Jonathan C.,Liu, Zhichang,Dyar, Scott M.,Zhang, Huacheng,Lei, Juying,Carmieli, Raanan,Sarjeant, Amy A.,Stern, Charlotte L.,Wasielewski, Michael R.,Sto American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.28

<P>Two redox-active bistable [2]catenanes composed of macrocyclic polyethers of different sizes incorporating both electron-rich 1,5-dioxynaphthalene (DNP) and electron-deficient 4,4′-bipyridinium (BIPY<SUP>2+</SUP>) units, interlocked mechanically with the tetracationic cyclophane cyclobis(paraquat-<I>p</I>-phenylene) (CBPQT<SUP>4+</SUP>), were obtained by donor–acceptor template-directed syntheses in a threading-followed-by-cyclization protocol employing Cu(I)-catalyzed azide–alkyne 1,3-dipolar cycloadditions in the final mechanical-bond forming steps. These bistable [2]catenanes exemplify a design strategy for achieving redox-active switching between two translational isomers, which are driven (i) by donor–acceptor interactions between the CBPQT<SUP>4+</SUP> ring and DNP, or (ii) radical–radical interactions between CBPQT<SUP>2(•+)</SUP> and BIPY<SUP>•+</SUP>, respectively. The switching processes, as well as the nature of the donor–acceptor interactions in the ground states and the radical–radical interactions in the reduced states, were investigated by single-crystal X-ray crystallography, dynamic <SUP>1</SUP>H NMR spectroscopy, cyclic voltammetry, UV/vis spectroelectrochemistry, and electron paramagnetic resonance (EPR) spectroscopy. The crystal structure of one of the [2]catenanes in its trisradical tricationic redox state provides direct evidence for the radical–radical interactions which drive the switching processes for these types of mechanically interlocked molecules (MIMs). Variable-temperature <SUP>1</SUP>H NMR spectroscopy reveals a degenerate rotational motion of the BIPY<SUP>2+</SUP> units in the CBPQT<SUP>4+</SUP> ring for both of the two [2]catenanes, that is governed by a free energy barrier of 14.4 kcal mol<SUP>–1</SUP> for the larger catenane and 17.0 kcal mol<SUP>–1</SUP> for the smaller one. Cyclic voltammetry provides evidence for the reversibility of the switching processes which occurs following a three-electron reduction of the three BIPY<SUP>2+</SUP> units to their radical cationic forms. UV/vis spectroscopy confirms that the processes driving the switching are (i) of the donor–acceptor type, by the observation of a 530 nm charge-transfer band in the ground state, and (ii) of the radical–radical ilk in the switched state as indicated by an intense visible absorption (ca. 530 nm) and near-infrared (ca. 1100 nm) bands. EPR spectroscopic data reveal that, in the switched state, the interacting BIPY<SUP>•+</SUP> radical cations are in a fast exchange regime. In general, the findings lay the foundations for future investigations where this radical–radical recognition motif is harnessed in bistable redox-active MIMs in order to achieve close to homogeneous populations of co-conformations in both the ground and switched states.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-28/ja3037355/production/images/medium/ja-2012-037355_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja3037355'>ACS Electronic Supporting Info</A></P>

Radically Enhanced Molecular Switches

Fahrenbach, Albert C.,Zhu, Zhixue,Cao, Dennis,Liu, Wei-Guang,Li, Hao,Dey, Sanjeev K.,Basu, Subhadeep,Trabolsi, Ali,Botros, Youssry Y.,Goddard, William A.,Stoddart, J. Fraser American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.39

<P>The mechanism governing the redox-stimulated switching behavior of a tristable [2]rotaxane consisting of a cyclobis(paraquat-<I>p</I>-phenylene) (CBPQT<SUP>4+</SUP>) ring encircling a dumbbell, containing tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) recognition units which are separated from each other along a polyether chain carrying 2,6-diisopropylphenyl stoppers by a 4,4′-bipyridinium (BIPY<SUP>2+</SUP>) unit, is described. The BIPY<SUP>2+</SUP> unit acts to increase the lifetime of the metastable state coconformation (MSCC) significantly by restricting the shuttling motion of the CBPQT<SUP>4+</SUP> ring to such an extent that the MSCC can be isolated in the solid state and is stable for weeks on end. As controls, the redox-induced mechanism of switching of two bistable [2]rotaxanes and one bistable [2]catenane composed of CBPQT<SUP>4+</SUP> rings encircling dumbbells or macrocyclic polyethers, respectively, that contain a BIPY<SUP>2+</SUP> unit with either a TTF or DNP unit, is investigated. Variable scan-rate cyclic voltammetry and digital simulations of the tristable and bistable [2]rotaxanes and [2]catenane reveal a mechanism which involves a bisradical state coconformation (BRCC) in which only one of the BIPY<SUP>•+</SUP> units in the CBPQT<SUP>2(•+)</SUP> ring is oxidized to the BIPY<SUP>2+</SUP> dication. This observation of the BRCC was further confirmed by theoretical calculations as well as by X-ray crystallography of the [2]catenane in its bisradical tetracationic redox state. It is evident that the incorporation of a kinetic barrier between the donor recognition units in the tristable [2]rotaxane can prolong the lifetime and stability of the MSCC, an observation which augurs well for the development of nonvolatile molecular flash memory devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-39/ja306044r/production/images/medium/ja-2012-06044r_0014.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja306044r'>ACS Electronic Supporting Info</A></P>

ON MEROMORPHIC SOLUTIONS OF NONLINEAR PARTIAL DIFFERENTIAL-DIFFERENCE EQUATIONS OF FIRST ORDER IN SEVERAL COMPLEX VARIABLES

Qibin Cheng,Yezhou Li,Zhixue Liu 대한수학회 2023 대한수학회보 Vol.60 No.2

This paper is concerned with the value distribution for meromorphic solutions $f$ of a class of nonlinear partial differential-difference equation of first order with small coefficients. We show that such solutions $f$ are uniquely determined by the poles of $f$ and the zeros of $f-c, f-d$ (counting multiplicities) for two distinct small functions $c, d$.

Dynamic clicked surfaces based on functionalised pillar[5]arene

Zhang, Huacheng,Strutt, Nathan L.,Stoll, Ragnar S.,Li, Hao,Zhu, Zhixue,Stoddart, J. Fraser Royal Society of Chemistry 2011 Chemical communications Vol.47 No.41

<P>A dynamic smart surface which was constructed by the self-assembly of an azobenzene-functionalised pillar[5]arene exhibits reversibly responsive morphologies towards UV and visible light as observed by TEM, SEM and AFM.</P> <P>Graphic Abstract</P><P>Pillar[5]arene monofunctionalized with azobenzene was used to prepare a photoresponsive surface which can switch between vesicles and solid particles. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cc14934b'> </P>

Xinhuang Tablets Improve Intestinal Barrier Function via Regulating Epithelial Tight Junctions in Dextran Sulfate Sodium-Induced Ulcerative Colitis Mice

Meizhu Wu,Aling Shen,Youqin Chen,Liya Liu,Li Li,Senthilkumar Sankararaman,Hongwei Chen,Bin Guan,Zhixue Zhan,Shuhua Nan,Thomas J. Sferra,Jun Peng 한국식품영양과학회 2021 Journal of medicinal food Vol.24 No.1

Intestinal mucosal barrier dysfunction is involved in the pathogenesis of inflammatory bowel disease, including ulcerative colitis (UC). Xinhuang tablets (XHTs) have been prescribed for several kinds of inflammatory diseases, including UC, whereas its possible underlying molecular mechanisms had never been explored. Mouse model of UC was constructed by DSS treatment and followed by XHT treatment. Disease activity index, histopathological of colonic tissue, tumor necrosis factor-alpha (TNF-α), and serum amyloid A (SAA) levels in serum were further assessed. The underlying mechanism was further explored by determination of the expression of epithelial tight junction-related protein. XHT administration ameliorated dextran sulfate sodium (DSS)-induced clinical symptoms, colonic histological injury, and decreased the circulating levels of TNF-α and SAA. Moreover, XHT treatment significantly increased the protein levels of zona occludens (ZO)-1, whereas decreased the levels of phosphorylation of Elk-1. In conclusion, this study confirmed the therapeutic effects of XHT treatment on UC in a DSS-induced mouse model, and indicated that by increasing expression of epithelial tight junctions and decreasing phosphorylation of Elk-1 might be one of the underlying mechanisms of XHT treatment on UC.