Electric field sensitivity of conducting hydrogels with interpenetrating polymer network structure

In this article, we reported the synthesis, structure and electric field sensitivity of polyacrylate/polyaniline (PAA/PANI) and poly(2-acrylamido-2-methyl propylsulfonic acid-acrylic acid)/polyaniline [P(AMPS-AA)/PANI] conducting hydrogels with an interpenetrating polymer network (IPN) structure. Scanning electron microscope showed that the conducting hydrogels presented porous structures consisting of PANI nanofibers. The results of Fourier-transform infrared and X-ray diffraction revealed that the PANI was in its conductive emeraldine state and partial crystallization. The unique morphology and molecular structure of the conducting hydrogels were expected to show unusual electric field responses. The conducting hydrogels were subjected to an electric field in NaCl solution for bending behaviors. It was demonstrated that the electric field response was improved by increasing aniline dosage, applied voltage and concentration of aqueous NaCl solution. The bending mechanism was attributed to polyelectrolyte hydrogel matrix and emeraldine PANI nanofibers.     

Facile fabrication of conducting polymer hydrogels via supramolecular self-assembly

We describe a simple and versatile method to fabricate conducting polymer hydrogels via supramolecular self-assembly between polymers and multivalent cations; the as-prepared hydrogels are potentially applicable in the fields of electrosensors, chemical release and artificial muscles.     

Hybrid organic-inorganic 1D and 2D frameworks with epsilon-Keggin polyoxomolybdates as building blocks

Organic-inorganic hybrid materials based on polyoxometalate building blocks with capping La3+ ions and bidentate oxygenated ligands have been obtained by reaction at room temperature of the [epsilon-PMo12O36(OH)4[La(H2O)4]]5+ polyoxocation with glutarate (C5H6O(2)(2-)) and squarate (C4O(4)(2-)) organic ligands. [epsilon-PMo12O37(OH)3[La(H2O)4(C5H6O4)0.5]4].21 H2O (1) and [epsilon-PMo12O39(OH)[La(H2O)6]2-[La(H2O)5(C4O4)0.5]2].17 H2O (2) form unprecedented 1D chains built from alternating polyoxocations and organic ligands connected through LaO links. The structures of these materials are compared to the 2D hybrid organic-inorganic framework [NC4H12]2-[Mo22O52(OH)18[La(H2O)4]2[La(CH3CO2)2]4].8H2O (3) isolated from the hydrothermal reaction of elemental precursors (MoO(4)(2-), Mo, La3+) in acetate buffer. Compound 3 is built from previously undescribed polyoxometalate units with twenty-two MoV centers capped by six La3+ ions, four of which are bridged by acetate ligands.     

Synthesis of aryl/alkyl building blocks for dendrimer and hyperbranched polymer synthesis

Several useful aryl/alkyl building blocks for dendrimer and hyperbranched polymer synthesis were prepared by Suzuki-Miyaura cross-coupling reactions and iododesilylation reactions. The iododesilylations were carried out with iodine monochloride (ICl) in methylene chloride and diethyl ether (10:1). This solvent combination lowered the reagents electrophilicity to the point that the iododesilylation still proceeded absolutely cleanly, but no direct iodination of alkyl-substituted aromatics occurred, which otherwise could not be avoided. [reaction: see text]     

Pickering emulsion-polymerized conducting polymer nanocomposites and their applications

The fabrication of conducting polymer nanocomposites via the Pickering emulsion polymerization process has become a spotlight of the research recently. One of the excellent applications of such conducting polymer nanocomposites is as an electrorheological (ER) fluid, which is a special type of smart suspension with controllable fluidity under an electric field. In this short review, we summarize the range of core–shell-structured conducting polymer nanocomposites synthesized by the Pickering emulsion method and their ER applications.     

Specific interactions in complexes formed by DNA and conducting polymer building blocks: guanine and 3,4-(ethylenedioxy)thiophene

In the present paper we report direct experimental evidence of the existence of hydrogen bonds between poly(3,4-(ethylenedioxy)thiophene) (PEDOT) and DNA complexes and bring deeper knowledge about how such interactions can take place in such species. To this end, we used both experimental and theoretical methodologies to examine the interactions between the building blocks composing these two macromolecules. The specific interaction natures between 3,4-(ethylenedioxy)thiophene (EDOT, E) and doubly protonated guanine (GH(2)(2+)) monomers have been investigated using UV-vis spectroscopy. Quantum mechanical calculations in the density functional theory (DFT) and time-dependent density functional theory (TDDFT) frameworks have been used to identify the structures of the possible complexes. These differ in the interaction pattern, and it was possible to interpret the absorption spectra in terms of intermolecular interactions. Our results allow verification of the previous hypothesis about the formation of specific N-H···O interactions between G-containing nucleotide sequences and PEDOT. Clearly, DFT calculations indicate that E:GH(2)(2+) complexes are stabilized by N-H···O interactions, which involve an E oxygen and the -NH and -NH(2) moieties of GH(2)(2+). Furthermore, TDDFT calculations are able to reproduce the absorption spectra (both energy gaps and relative oscillator strength magnitudes) of E and GH(2)(2+), as well as the complex.     

Synthesis of 3,3-disubstituted oxetane building blocks

The synthesis of two different sets of 3,3-disubstituted oxetane building blocks is described. These molecules can be usefully incorporated in more complex structures to modulate their metabolic and physicochemical properties. The synthetic pathways are general and could be exploited for the synthesis of many other related derivatives.     

Assembly and decomposition of building blocks to analyze polymer NEXAFS spectra

The poly(ethylene-terephthalate) and poly(bisphenol-A-carbonate) compounds are used to illustrate the possibilities and limitations of building-block analysis of polymer near-edge X-ray absorption spectra. Experimental spectra obtained for thin polymer films are analyzed using theoretical static exchange calculations of C_1s and O_1s excitation spectra on model molecules selected as possible building blocks. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 749–765, 1997     

Synthesis and characterization of a new conducting polymer composite

Organic conductive composite films have been synthesized by electropolymerization of pyrrole in the presence of chitosan and p-toluene sulfonic acid sodium salt. The obtained conductive polymer composite films have been characterized by Fourier Transform Infrared spectroscopy, dynamic mechanical analysis, scanning electron microscopy, X-ray diffraction and conductivity measurements. The prepared polymer composite films had the amorphous structure and exhibited the enhanced conductivity and mechanical properties due to the presence of chitosan in the composite films.     

Two unprecedented 1D coordination polymer chains based on tetranuclear copper(II) building blocks

The reaction of copper(II) sulfate with pyridine in DMF or methanol yield two unprecedented Cu(II) coordination polymers {[Cu₄(μ₄-O)(py)₄(SO₄)₄][μ-Cu(py)(DMF)₂]}_n(1) and {[Cu₄(μ₄-O)(py)₄(SO₄)₄][μ-Cu(py)₄]}_n(2), respectively. Single-crystal X-ray diffraction indicated that compound 1 crystallizes in the monoclinic system, space group p2(1)/n, a=14.542(5) Å, b=16.359(5) Å, c=18.951(5) Å, β=92.047(5)°, V=4505(2) Å³, Z=4 while 2 is monoclinic C2/c, a=23.078(5) Å, b=10.214(5) Å, c=23.142(5) Å, β=115.471(5)°, V=4925(3) Å³, Z=4. Both of the two compounds consist of tetrahedral tetranuclear [Cu₄(μ₄-O)(py)₄(SO₄)₄] clusters that are bridged by pentacoordinated Cu atom for 1 or hexacoordinated Cu atoms for 2 through the sulfate oxygen to form the infinite one-dimensional polymer chains.     

Properties of conductive polymer hydrogels and their application in sensors

Conductive polymer hydrogels (CPHs), which combine the unique advantages of hydrogels and organic conductors, have received wide attention due to their adjustable mechanical properties, biocompatibility, self‐healing, hydrophilicity, and ease of preparation. With doping engineering and incorporation with other functional nanomaterials, CPHs have exhibited excellent physical/chemical properties. CPHs have been widely used in various electronic devices, especially in the field of sensors due to its sensitivity to external stimuli. This review summarizes recent progress in CPHs from the aspect of the CPHs' properties and their application in advanced sensor technology. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1606–1621     

A 1D zinc(II) polymer with W-like pentanuclear secondary building blocks constructed by 2,6-pyridine-diacylhydrazone ligand

A 1D zinc(II) coordination polymer with W-like pentanuclear secondary building blocks constructed by 2,6-bis[(3-methoxysalicylidene)hydrazinocarbonyl]pyridine (H₄Bmshp) ligand, {[Zn₅(Bmshp)(CH₃COO)₅Cl(H₂O)₃]·2H₂O} _n , was synthesized and characterized by elemental analysis, IR, X-ray diffraction, and thermogravimetric analyses. It has the highest nuclear unit constructed by one 2,6-pyridine-diacylhydrazone ligand so far. The luminescent property of the compound was studied. It shows an emission with a maximum at 522 nm upon excitation at 450 nm.     

Synthesis of a novel highly conjugated conducting polymer

The new conjugated polyacetylene derivative dehydrated poly(4-hydroxy-4-phenyl-1-butyne) [dehydrated poly(HPB)] was synthesized from poly(4-hydroxy-4-phenyl-1-butyne) [poly(HPB)], which was obtained by the polymerization of 4-hydroxy-4-phenyl-1-butyne. The resulting dehydrated poly(HPB) was soluble in common organic solvents. The dehydrated poly(HPB) was found to have extended conjugated polyene structure. The dehydrated poly(HPB) was thermally stable up to 300°C. The electrical conductivity of I₂-doped dehydrated poly(HPB) was 10⁻² S cm⁻¹. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 949–953, 1998     

Synthesis of chiral building blocks for cephalostatin analogues

The present paper describes the synthesis of 5‐azido‐6‐ketones (14) and 6‐hydroxy‐5‐ketone (20) from Hajos Wiechert ketone as chiral building blocks for cephalostatin analogues. The synthesis of symmetric cephalostatin analogue from 6‐hydroxy‐5‐ketone has also been reported. The characterization of the each synthesized compounds was carried out by IR, ¹H‐NMR, ¹³C‐NMR and High resolution Mass Spectrometry.     

Synthesis of cyclic peptidomimetics from aldol building blocks

Aldol products (3-hydroxy acids) with an allyl-protected hydroxy group were converted to amino alcohols by Curtius rearrangement. Combination of the carboxylic acid with the amino alcohols gave the amides 10. Ring-closing metathesis led to the 12-membered lactams 12 as mixtures of E/Z-isomers. The scheme was also transferred to the solid-phase. In this case the macrolactams are formed via cyclorelease. For a pair of E/Z-isomers the solution conformation was determined by ROESY spectroscopy.     

Synthesis and reactivity of pelletierine-derived building blocks and pelletierine analogs

Lycopodium alkaloids are unique (and often impressive in terms of structures) polycyclic alkaloids that attract great interest from a biological point of view and that also provide ideal targets for total synthesis. Propylpiperidine units closely related to pelletierine are involved in the biosynthesis of these alkaloids. Therefore, stable pelletierine-like compounds, especially a (R)-phenylglycinol-based oxazolopiperidine analog, were prepared and their reactivity investigated. The compounds described in this work expand the tool-box of small building blocks in the piperidine series and pelletierine analogs and could be suitable for the synthesis of Lycopodium alkaloids following biosynthetically inspired strategies.     

Pendant macrocyclic metallic building blocks for the design of cyano-bridged heterometallic complexes with 1D chain and 2D layer structures

A series of cyano-bridged Ni(II)-Cr(I/III) complexes have been synthesized by the reactions of hexaazacyclic Ni(II) complexes with [Cr(CN)(6)](3-) or [Cr(CN)(5)(NO)](3-). Using the tetravalent Ni(II) complex [Ni(H(2)L(2))](4+) (L(2) = 3,10-bis(2-aminoethyl)-1,3,6,8,10,12-hexaazacyclotetradecane), one-dimensional chainlike complexes were produced and subject to magnetic studies, affording the intermetallic magnetic exchange constants of J(1) = +0.23 cm(-1) and J(2) = +8.4 cm(-1) for the complex [Ni(H(2)L(2))][Cr(CN)(5)(NO)]ClO(4).5H(2)O (1) and of J = +5.9 cm(-1) for the complex [Ni(H(2)L(2))](4)[Cr(CN)(6)](5)OH.15H(2)O (2). X-ray diffraction analysis shows that complex 1 has a zigzag chain structure, whereas complex 2 consists of a branched chain structure. Complex 2 exhibits antiferromagnetic ordering at 8.0 K (T(N)). When an octahedral Ni(II) complex cis-[NiL(3)(en)](2+) (en = 1,2-ethylenediamine, L(3) = 3,10-bis(2-hydroxyethyl)-1,3,5,8,10,12-hexaazacyclotetradecane) was used for the synthesis, the common 2D honeycomb-layered complex [NiL(3)](3)[Cr(CN)(5)(NO)](2).8H(2)O (3) was obtained, which has a T(N) value of 3.3 K. Below T(N), a metamagnetic behavior was observed in complexes 2 and 3.     

Synthesis of conjugates based on chlorin and isosteviol building blocks

Conjugates containing ent-beyerane carbocyclic frameworks on the periphery of a porphyrin macrocycle were prepared by acylation of chlorin e₆ derivatives with hydroxyl and amino groups using ent-16-ketobeyeran19-oic acid chloride (diterpenoid isosteviol). Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 165-169, March-April, 2009.     

Synthesis and solid-phase application of suitably protected gamma-hydroxyvaline building blocks

Recently, an unexpected modified residue, gamma-hydroxy-D-valine (D-Hyv), was identified within ribosomally expressed polypeptide chains of four conopeptides from the venoms of Conus gladiator and Conus mus. To assemble Hyv-containing peptides, we have explored several routes for the synthesis of appropriately functionalized Hyv building blocks. D-Hyv was produced from D-Val by using a variation of the previously published K2PtCl4/CuCl2 oxidative method. Direct synthesis of Boc- or Cbz-D-Hyv lactone proceeded in low yield; additionally, the lactones are too unreactive for solid-phase applications. 9-Borabicyclononane or copper-complexed D-Hyv was prepared and treated with tert-butyldimethylsilyl trifluoromethanesulfonate (TBDMSOTf) to produce D-Hyv(O-TBDMS). The most efficient complex disruption was achieved by Chelex 110 resin (Na+ form) treatment of copper-complexed D-Hyv(O-TBDMS). Reaction of D-Hyv(O-TBDMS) with Fmoc-OSu produced Fmoc-D-Hyv(O-TBDMS) in 26% yield from D-Val. The Fmoc-D-Hyv(O-TBDMS) diastereomers were separated by preparative RP-HPLC in 13% yield from D-Val. Fmoc-D-Hyv(O-TBDMS) was used for the synthesis of the conopeptide gld-V* from Conus gladiator. The isolated synthetic and natural products had coincidental mass and NMR spectra. The methodology presented herein will greatly facilitate biological studies of Hyv-containing sequences, such as receptor responses to hydroxylated versus nonhydroxylated conopeptides and the relative susceptibility of proteins to modification by oxidative stress.