Reactive polythiophenes with zincke salt structure: Synthesis,polymer reactions,and chemical properties

Polythiophenes with reactive Zincke salt structure, such as PThThPy⁺DNP(Cl^?)Th , were synthesized by the oxidation polymerization of 3′‐(4‐N‐(2,4‐dinitrophenyl)pyridinium chloride)‐2,2′:5′,2″‐terthiophene ( ThThPy⁺DNP(Cl^?)Th ) with iron(III) chloride or copper(II) trifluoromethanesulfonate. The reaction of PThThPy⁺DNP(Cl^?)Th with R‐NH₂ (R = n‐hexyl (Hex) and phenyl (Ph)) substituted the 2,4‐dinitrophenyl group into the R group with the elimination of 2,4‐dinitroaniline to yield PThThPy⁺R(Cl^?)Th . Similarly, model compounds, ThThPy⁺R(Cl^?)Th (R = Hex and Ph), were also synthesized. In contrast to the photoluminescent ThThPyTh and PThThPyTh , the compounds PThThPy⁺DNP(Cl^?)Th , PThThPy⁺R(Cl^?)Th , and ThThPy⁺R(Cl^?)Th showed no photoluminescence because their internal pyridinium rings acted as quenchers. Cyclic voltammetry measurements suggested that PThThPy⁺DNP(Cl^?)Th received an electrochemical reduction of the pyridinium and 2,4‐dinitrophenyl groups and oxidation of the polymer backbone. PThThPy⁺DNP(Cl^?)Th was electrically conductive (ρ = 2.0 × 10^?6 S cm^?1) in the non‐doped state. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Gold nanosphere propulsion by using femtosecond laser-excited enhanced near field

We propose nanosphere propulsion by using femtosecond laser-excited enhanced near field based on the theoretical calculations and experimental study. The optical intensity distribution and enhancement around a gold nanosphere on a silicon substrate was simulated by a 3D finite-difference time-domain method. The sphere velocities and propelled angles were calculated based on the optical intensity distribution. In our simulation, we calculated the optical intensity for the gold nanospheres with a diameter ranging from 100 to 600 nm. Calculation results show that the sphere velocity was fairly constant for the diameters ranging from 100 to 250 nm, while the velocity decreased for diameters larger than 250 nm. The propelled angle could be controlled up to only 4.6° by varying the incident angles of p-polarized waves. We have demonstrated the gold nanosphere propulsion in experiment. The gold nanospheres with a diameter of 200 nm were used in our experiments. The propelled gold particles have been melted by laser irradiation and deposited on the receiver substrate. The size and spatial distributions of gold particles have been investigated. The decrease in the laser spot size and the gap distance between the donor and receiver substrate would realize the reduction in the existence region of gold particles on the receiver substrate.     

Temperature and pH stability of cellouronic acid

Cellouronic acid (CUA), (1 → 4)-β-d-polyglucuronate sodium salt, was prepared from regenerated cellulose by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation in water at pH 10. Changes in chemical structure and degree of polymerization (DP) of CUA by treatment in water under various pH and temperature conditions were studied to evaluate the stability of CUA. No depolymerization occurred on CUA in water at pH 1.0–7.0 and room temperature, while clear depolymerization took place at pH 10 and 13 by β-elimination. When heated in water at >50 °C, CUA was depolymerized by hydrolysis at pH 1.0 and 4.8, and by both hydrolysis and β-elimination at pH 7.0. Kinetic studies showed that CUA depolymerization rate constant was roughly increased with increasing the pH or temperature. Especially, the depolymerization rate constant at pH 13 was approximately 128 and 55 times greater than those at pH 1.0 and 10, respectively, at 60 °C. Activation energies of hydrolysis and β-elimination of CUA were approximately 100 and 20 kJ mol⁻¹, respectively.     

Conformation of ATP and ADP Molecules in Aqueous Solutions Determined by High-Energy X-ray Diffraction

High-energy X-ray diffraction measurements were carried out at 26 °C for aqueous 1.0, 2.0 and 2.05 mol% disodium adenosine 5′-triphosphate (ATP) and 2.0 and 2.05 mol% disodium adenosine 5′-diphosphate (ADP) solutions in order to obtain direct experimental information on the intramolecular conformations of ATP and ADP molecules in aqueous solutions. Observed interference terms were analyzed in terms of the intramolecular geometry of the ATP and ADP molecules. Dihedral angles between adenine and the ribose group (t ₁), ribose-ring and methylene group of ribose (t ₂), and the methylene group of ribose and triphosphate (or diphosphate) group (t ₃), were determined through the least-squares fitting procedure of the observed interference term.     

Structural Versatility in Slide‐Ring Gels: Influence of Co‐Threaded Cyclodextrin Spacers

We describe a one‐pot strategy for the fabrication of novel slide‐ring (SR) gels based on supramolecular polyrotaxane structures with cyclodextrin‐derived cross‐links and additional free cyclodextrin ring spacers co‐threaded onto the polymer backbones. Photoinitiated thiol‐yne click coupling leads to facile hydrogel fabrication from pseudo‐polyrotaxanes prepared in situ from β‐cyclodextrin derivatives and bifunctional polyethylene glycol (PEG). The obtained SR gels were characterized by NMR spectroscopy using a polyrotaxane model compound with the ratio of cyclodextrin sliding spacers to PEG backbone controlled by adjusting the feed ratio of the starting materials. This structural tuning leads to dramatic changes in the rheological properties, mechanical properties, and swelling behavior of the SR gels. In addition, the coupling of simple synthetic procedures with enhanced properties offers a versatile approach to novel elastomeric materials. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1156–1165     

Bi-continuous macroporous polymer derived from oligo-ethylene oxide di-vinyl ether by a cationic polymerization

We have newly developed a bi-continuous macroporous polymer derived from oligo-ethylene oxide di-vinyl ether by cationic polymerization. Although vinyl ether is not easily polymerized using radical polymerization in its homo-polymerization, we have found that a cationic polymerization with a combination of good and poor solvents for the glowing polymer chain realized bi-continuous macroporous polymer as the first example of cross-linked, macroporous vinyl ether polymer.     

Stabilization of a kinetically favored nanostructure: surface ROMP of self-assembled conductive nanocoils from a norbornene-appended hexa-peri-hexabenzocoronene

Newly designed norbornene-appended hexabenzocoronene 1 self-assembles, upon diffusion of an Et(2)O vapor into its CH(2)Cl(2) solution, to form either graphitic nanocoils or nanotubes, depending on the self-assembling conditions. The coiled assembly, selectively formed at 15 degrees C, is a kinetic intermediate for the tubular assembly and transforms into nanotubes on standing at 25 degrees C. However, post-ring-opening metathesis polymerization of the norbornene pendants of 1 enhances the thermal stability of the coiled assembly as well as the tubular one and disables a thermodynamic coil-to-tube transition. The polymerized nanocoils show an electroconductivity of 1 x 10(-)(4) S cm(-)(1) upon doping with I(2), while the nonpolymerized nanocoils are disrupted upon being doped.     

A third mode of DNA binding: Phosphate clamps by a polynuclear platinum complex

We describe a 1.2 A X-ray structure of a double-stranded B-DNA dodecamer (the Dickerson Dodecamer, DDD, [d(CGCGAATTCGCG)]2) associated with a cytotoxic platinum(II) complex, [{trans-Pt(NH3)2(NH2(CH2)6(NH3+)}2-mu-{trans-Pt(NH3)2(NH2(CH2)6NH2)2}] (TriplatinNC). TriplatinNC is a multifunctional DNA ligand, with three cationic Pt(II) centers, and directional hydrogen bonding functionalities, linked by flexible hydrophobic segments, but without the potential for covalent interaction. TriplatinNC does not intercalate nor does it bind in either groove. Instead, it binds to phosphate oxygen atoms and thus associates with the backbone. The three square-planar tetra-am(m)ine Pt(II) coordination units form bidentate N...O...N complexes with OP atoms, in a motif we call the Phosphate Clamp. The geometry is conserved among the 8 observed phosphate clamps in this structure. The interaction appears to prefer O2P over O1P atoms (frequency of interaction is O2P > O1P, base and sugar oxygens > N). The high repetition and geometric regularity of the motif suggests that this type of Pt(II) center can be developed as a modular nucleic acid binding device with general utility. TriplatinNC extends along the phosphate backbone, in a mode of binding we call "Backbone Tracking" and spans the minor groove in a mode of binding we call "Groove Spanning". Electrostatic forces appear to induce modest DNA bending into the major groove. This bending may be related to the direct coordination of a sodium cation by a DNA base, with unprecedented inner-shell (direct) coordination of penta-hydrated sodium at the O6 atom of a guanine.     

Nanoscale spherical architectures fabricated by metal coordination of multiple dipyrrin moieties

Phenylethynyl-bridged dipyrrin "dimers" have performed ZnII complexation to give coordination polymers, which provided the fluorescent colloidal spherical objects in solution as well as on the substrate according to the spacer units. Using a mixture of THF and water, unique morphologies, such as bell-shaped and "golf ball"-like architectures, were observed.     

Chromatographic separation for domoic acid using a fragment imprinted polymer

A method for real-time visualisation of reactions performed in-capillary by the technique of electrophoretically mediated microanalysis (EMMA) is described, using a two dimensional imaging detection system. The UV absorbance detector is based on a complementary metal oxide semiconductor (CMOS) active pixel sensor. Imaging of analyte peaks absorbing at 200 nm and migrating over length of 14 mm in the capillary dimension allowed measurement of velocities and lengths of reactant and product zones. By contrast with use of single point detection, velocities of species generated by reaction anywhere within the capillary are readily measured with CMOS imaging: this is of particular benefit for EMMA experiments where reaction occurs during zone overlap. For the oxidation of glutathione by hydrogen peroxide, reaction times were varied over the range 0.5-20 s by changing voltages for electrokinetic injection and zone migration, and reactant and product peak areas were obtained for kinetic analysis of the reaction. The use of EMMA conditions with CMOS imaging allows the whole process of reaction, separation and quantification to be carried out in nanolitre volumes on-capillary in a single run on a time scale of less than 5 min.