Name: reductive electropolymerization of a vinyl-containing poly-pyridyl complex on glassy carbon and fluorine-doped tin oxide electrodes
Uploaded: 2015-01-30T15:00:00
Description: Watch this Scientific Journal Video about Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes at JoVE.com

We acknowledge the Virginia Military Institute (VMI) Department of Chemistry for support of electrochemical experiments and instrumentation (L.S.C. and J.T.H.). The VMI Office of the Dean of Faculty supported production fees associated with JoVE publications. We acknowledge the UNC EFRC: Center for Solar Fuels, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001011, for support of compound synthesis and materials characterization (D.P.H).

1. Synthesize 1
Synthesize&#160;1 (PhTpy is 4&#39;-phenyl-2,2&#39;:6&#39;,2&#39;&#39;-terpyridine; 5,5&#8217;-dvbpy is 5,5&#39;-divinyl-2,2&#39;-bipyridine; Figure 4) according to the procedure outlined previously.18
2. Prepare 1.3 mM Monomer Solution of 1 in an Electrolyte Solution
<ol>
	<li>Prepare a 0.1 M stock electrolyte solution of tetra-n-butylammonium hexafluorophosphate,...

<ol>
	<li>Abru&#241;a, H. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coordination+chemistry+in+two+dimensions:+chemically+modified+electrodes.">Coordination chemistry in two dimensions: chemically modified electrodes.</a> Coordination Chemistry Reviews. 86, 135-189 (1988).</li><li>Waltman, R. J., Bargon, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrically+conducting+polymers:+a+review+of+the+electropolymerization+reaction,+of+the+effects+of+chemical+structure+on+polymer+film+properties,+and+of+applications+towards+technology.">Electrically conducting polymers: a review of the electropolymerization reaction, of the effects of chemical structure on polymer film properties, and of applications towards technology.</a> Canadian Journal of Chemistry. 64, 76-95 (1986).</li><li>Zhong, Y. -. 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Photochemically produced molecular voids.</a> Inorganic Chemistry. 31, 5521-5525 (1992).</li><li>Devenney, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Excited+State+Interactions+in+Electropolymerized+Thin+Films+of+Ru(II).">Excited State Interactions in Electropolymerized Thin Films of Ru(II).</a> Os(II), and Zn(II) Polypyridyl Complexes. The Journal of Physical Chemistry A. 101, 4535-4540 (1997).</li><li>Moss, J. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensitization+and+Stabilization+of+TiO2+Photoanodes+with+Electropolymerized+Overlayer+Films+of+Ruthenium+and+Zinc+Polypyridyl+Complexes:+A+Stable+Aqueous+Photoelectrochemical+Cell.">Sensitization and Stabilization of TiO2 Photoanodes with Electropolymerized Overlayer Films of Ruthenium and Zinc Polypyridyl Complexes: A Stable Aqueous Photoelectrochemical Cell.</a> Inorganic Chemistry. 43, 1784-1792 (2004).</li><li>Yang, J., Sykora, M., Meyer, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Electropolymerization of Vinylbipyridine Complexes of Ruthenium(II) and Osmium(II) in SiO2 Sol&#8722;Gel Films. Inorganic Chemistry. 44, 3396-3404 (2005).</li><li>Nie, H. -. J., Shao, J. -. Y., Wu, J., Yao, J., Zhong, Y. -. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Reductive+Electropolymerization+of+Metal+Complexes+with+5,5&#8242;-Divinyl-2,2&#8242;-Bipyridine.">Synthesis and Reductive Electropolymerization of Metal Complexes with 5,5&#8242;-Divinyl-2,2&#8242;-Bipyridine.</a> Organometallics. 31, 6952-6959 (2012).</li><li>Yao, C. -. J., Zhong, Y. -. W., Nie, H. -. J., Abru&#241;a, H. D., Yao, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Near-IR+Electrochromism+in+Electropolymerized+Films+of+a+Biscyclometalated+Ruthenium+Complex+Bridged+by+1,2,4,5-Tetra(2-pyridyl)benzene.">Near-IR Electrochromism in Electropolymerized Films of a Biscyclometalated Ruthenium Complex Bridged by 1,2,4,5-Tetra(2-pyridyl)benzene.</a> Journal of the American Chemical Society. 133, 20720-20723 (2011).</li><li>Harrison, D. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coordination+Chemistry+of+Single-Site+Catalyst+Precursors+in+Reductively+Electropolymerized+Vinylbipyridine+Films.">Coordination Chemistry of Single-Site Catalyst Precursors in Reductively Electropolymerized Vinylbipyridine Films.</a> Inorganic Chemistry. 52, 4747-4749 (2013).</li><li>Calvert, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+and+mechanistic+investigations+of+the+reductive+electrochemical+polymerization+of+vinyl-containing+complexes+of+iron(II),+ruthenium(II),+and+osmium(II).">Synthetic and mechanistic investigations of the reductive electrochemical polymerization of vinyl-containing complexes of iron(II), ruthenium(II), and osmium(II).</a> Inorganic Chemistry. 22, 2151-2162 (1983).</li><li>Moss, J. A., Argazzi, R., Bignozzi, C. A., Meyer, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electropolymerization+of+Molecular+Assemblies.">Electropolymerization of Molecular Assemblies.</a> Inorganic Chemistry. 36, 762-763 (1997).</li><li>Deronzier, A., Eloy, D., Jardon, P., Martre, A., Moutet, J. -. 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W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electropolymerization+of+vinylpyridine+and+vinylbipyridine+complexes+of+iron+and+ruthenium:+homopolymers,+copolymers,+reactive+polymers.">Electropolymerization of vinylpyridine and vinylbipyridine complexes of iron and ruthenium: homopolymers, copolymers, reactive polymers.</a> Inorganic Chemistry. 21, 2153-2161 (1982).</li><li>Younathan, J. N., Wood, K. S., Meyer, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrocatalytic+reduction+of+nitrite+and+nitrosyl+by+iron(III)+protoporphyrin+IX+dimethyl+ester+immobilized+in+an+electropolymerized+film.">Electrocatalytic reduction of nitrite and nitrosyl by iron(III) protoporphyrin IX dimethyl ester immobilized in an electropolymerized film.</a> Inorganic Chemistry. 31, 3280-3285 (1992).</li><li>Ikeda, T., Schmehl, R., Denisevich, P., Willman, K., Murray, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Permeation+of+electroactive+solutes+through+ultrathin+polymeric+films+on+electrode+surfaces.">Permeation of electroactive solutes through ultrathin polymeric films on electrode surfaces.</a> Journal of the American Chemical Society. 104, 2683-2691 (1982).</li><li>Concepcion, J. 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Electropolymerization offers a large range of controllable variables that are not common to other techniques. In addition to standard reaction variables like reagent (monomer) concentration, temperature, solvent, etc., electropolymerization can be additionally controlled by electrochemical experiment parameters common to electrochemical methods. CV scan rates, switching potentials, and number of cycles affect the deposition of electropolymers. For example, as the number of cycles through the ligand reduction wav...

Electropolymerization is a polymerization technique that utilizes an applied potential to initiate the polymerization of monomeric precursors directly at the surface of an electrode and has been exploited to produce thin electroactive and/or photochemically active polypyridyl films on electrode and semiconductor surfaces.1-4 Electrocatalysis,5-10 electron transfer,11,12 photochemistry,13-16 electrochromism,17 and coordination chemistry18 have been investigated in electropolymerized films. This technique was first developed at the University of North Carolina in a Meyer-Murray collaboration for the electropolymerization of vinyl3,5,7,8,11-15,19,20 and pyrrole6,9,21-24 derivatized metal complexes on a variety of conducting substrates. Figure 1 presents a number of common pyridyl based ligands that, when coordinated to metal complexes, have produced electropolymers. In reductive electropolymerization, electropolymerization of vinyl containing compounds occurs upon the reduction of pyridyl ligands conjugated to vinyl groups, while with pyrrole-functionalized ligands, electropolymerization is initiated by oxidation of the pyrrole moieties, resulting in oxidative electropolymerization (Figure 2). Electropolymerization technology was developed with the goal of providing a generalized methodology for directly attaching virtually any transition metal complex to any electrode. The versatility of the method opens the door to numerous investigations of electropolymer modified electrodes.
In contrast to other attachment strategies, which involve direct bonding to the electrode, electropolymerization offers the advantage of not requiring electrode surface pre-modification. Therefore it can be applied to any number of conducting substrates, regardless of surface composition or morphology.4,10,25,26 This versatility is a result of changing physical properties as the polymer length grows; the monomers are soluble in the electrolytic solution but as polymerization occurs and cross-linking rigidifies the film, precipitation and physical adsorption the electrode surface occurs (Figure 3).27
Compared to oxide surface-bound carboxylate, which are unstable on oxide surfaces in water, or phosphonate-derivatized complexes, which are unstable at elevated pH&#39;s, commonly used in solar fuels research, these interfacial electrode-polymer film structures offer the added benefit of stability in a variety of media including organic solvents and water over a large pH range (0-14).28-30 Electropolymerization can also deposit films with large ranges of apparent surface coverages, from sub-monolayer to dozens or hundreds of equivalents monolayer, whereas carboxylate or phosphonate-derivatized complexes-interface structures are limited to monolayer surface coverages.
Although any number of vinyl or pyrrole containing pyridyl and polypyridyl compounds are capable of polymerization, [RuII(PhTpy)(5,5&#8217;-dvbpy)(MeCN)](PF6)2, (1; PhTpy is 4&#39;-phenyl-2,2&#39;:6&#39;,2&#39;&#39;-terpyridine; 5,5&#8217;-dvbpy is 5,5&#39;-divinyl-2,2&#39;-bipyridine; Figure 4) will be utilized as a model complex to demonstrate reductive electropolymerization on glassy carbon and fluorine-doped tin oxide, FTO, electrodes in this report. 1 is an example of a modern electropolymer precursor that has potential electrocatalytic applications and, due to its metal-to-ligand charge transfer, MLCT, absorption spectrum lying in the visible region of the light spectrum, can be investigated with UV-Vis spectroscopy.18,30 Please note that some results presented here for 1 have already been published in a slightly modified form.18

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			<td height="21" style="height:21px;width:384px;">Name of Reagent/ Equipment</td>
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			<td height="20" style="height:20px;">Tetrabutylammonium hexafluorophosphate for electrochemical analysis, &#8805;99.0%,&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>86879-25G</td>
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			<td height="20" style="height:20px;width:384px;">Acetonitrile&#160;(Optima LC/MS), Fisher Chemical</td>
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			<td height="20" style="height:20px;">3 mm dia. Glassy Carbon Working Electrode</td>
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			<td height="20" style="height:20px;">Non-Aqueous Ag/Ag+ Reference Electrode w/ porous Teflon Tip</td>
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reductive electropolymerization of a vinyl-containing poly-pyridyl complex on glassy carbon and fluorine-doped tin oxide electrodes

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is one surface modification technique that electrodeposits a polymeric film at the surface of an electrode by utilizing an applied potential to initiate the polymerization of substrates in the Helmholtz layer. This useful technique was first established by a Murray-Meyer collaboration at the University of North Carolina at Chapel Hill in the early 1980s and utilized to study numerous physical phenomena of films containing inorganic complexes as the monomeric substrate. Here, we highlight a procedure for coating electrodes with an inorganic complex by performing reductive electropolymerization of the vinyl-containing poly-pyridyl complex onto glassy carbon and fluorine doped tin oxide coated electrodes. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization but are far less sensitive to oxygen and water.

Electropolymer growth is most easily recognized when observing the progress of the prescribed CV experiment (Protocol Text STEP 3.3.2). Figure 5 exemplifies electropolymer growth on a 0.071 cm2 (3 mm diameter) glassy carbon electrode with 1. The first cycle of the experiment produces a voltammogram roughly resembling that which is expected for a ruthenium solution of similar concentration (Figure 5, black trace) but upon successive cycles, through the 1st...

Watch this Scientific Journal Video about Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes at JoVE.com

Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes

A procedure for performing reductive electropolymerization of vinyl-containing compounds onto glassy carbon and fluorine doped tin-oxide coated electrodes is presented. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization.

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is ...

reductive-electropolymerization-vinyl-containing-poly-pyridyl-complex

Research

JoVE Journal

Chemistry

Improved In-gel Reductive &#946;-Elimination for Comprehensive O-linked and Sulfo-glycomics by Mass Spectrometry

Separation of proteins by SDS-PAGE followed by in-gel proteolytic digestion of resolved protein bands has produced high-resolution proteomic analysis of biological samples. Similar approaches, that would allow in-depth analysis of the glycans carried by glycoproteins resolved by SDS-PAGE, require special considerations in order to maximize recovery and sensitivity when using mass spectrometry (MS) as the detection method. A major hurdle to be overcome in achieving high-quality data is the removal of gel-derived contaminants that interfere with MS analysis. The sample workflow presented here is robust, efficient, and eliminates the need for in-line HPLC clean-up prior to MS. Gel pieces containing target proteins are washed in acetonitrile, water, and ethyl acetate to remove contaminants, including polymeric acrylamide fragments. O-linked glycans are released from target proteins by in-gel reductive &#946;-elimination and recovered through robust, simple clean-up procedures. An advantage of this workflow is that it improves sensitivity for detecting and characterizing sulfated glycans. These procedures produce an efficient separation of sulfated permethylated glycans from non-sulfated (sialylated and neutral) permethylated glycans by a rapid phase-partition prior to MS analysis, and thereby enhance glycomic and sulfoglycomic analyses of glycoproteins resolved by SDS-PAGE.

In order to comprehensively explore the diversity of O-linked glycans, a new procedure for in-gel reductive &#946;-elimination, combined with permethylation and a rapid phase-partition method, is applied to the analysis of O-linked glycans directly released from glycoproteins resolved by SDS-PAGE and amenable to subsequent glycomic analysis by mass spectrometry.

Separation of proteins by SDS-PAGE followed by in-gel proteolytic digestion of resolved protein bands has produced high-resolution proteomic analysis of ...

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

Transport of Surface-modified Carbon Nanotubes through a Soil Column

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, electronics and biomedical applications. Due to their accelerating production and use, CNTs constitute a potential environmental risk if they are released to soil and groundwater systems. It is therefore essential to improve the current understanding of environmental fate and transport of CNTs. The transport and retention of CNTs in both natural and artificial media have been reported in literature, but the findings widely vary and are thus not conclusive. There are a number of physical and chemical parameters responsible for variation in retention and transport. In this study, a complete procedure of selected multiwalled carbon nanotubes (MWCNTs) is presented starting from their surface modification to a complete set of laboratory column experiments at critical physical and chemical scenarios. Results indicate that the stability of the commercially available MWCNTs are critical with their attached surface functional group which can also influence the transport and retention of MWCNT through the surrounding medium.

Surface properties of a nanoparticle are important for their interaction with the surrounding medium. Therefore the surface modification of carbon nanotubes can be critical for their transport and retention through porous media. Here, lab scale column experiments are used to understand the possible transport and retention of these nanoparticles.

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, ...

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide ...

On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes

The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The composition of heavy crude oils and shale oils varies substantially depending on the origin of the mixture. In particular they contain an increased amount of nitrogen containing compounds compared to the conventionally used sweet crude oils. As nitrogen compounds have an influence on the operation of thermal processes occurring in coker units and steam crackers, and as some species are considered as environmentally hazardous, a detailed analysis of the reactions involving nitrogen containing compounds under pyrolysis conditions provides valuable information. Therefore a novel method has been developed and validated with a feedstock containing a high nitrogen content, i.e., a shale oil. First, the feed was characterized offline by comprehensive two-dimensional gas chromatography (GC &#215; GC) coupled with a nitrogen chemiluminescence detector (NCD). In a second step the on-line analysis method was developed and tested on a steam cracking pilot plant by feeding pyridine dissolved in heptane. The former being a representative compound for one of the most abundant classes of compounds present in shale oil. The composition of the reactor effluent was determined via an in-house developed automated sampling system followed by immediate injection of the sample on a GC &#215; GC coupled with a time-of-flight mass spectrometer (TOF-MS), flame ionization detector (FID) and NCD. A novel method for quantitative analysis of nitrogen containing compounds using NCD and 2-chloropyridine as an internal standard has been developed and demonstrated.

A method combining comprehensive two-dimensional gas chromatography with nitrogen chemiluminescence detection has been developed and applied to on-line analysis of nitrogen containing compounds in a complex hydrocarbon matrix.

The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The ...

Investigations on the Ga(III) Complex of EOB-DTPA and Its 68Ga Radiolabeled Analogue

We demonstrate a method for the isolation of EOB-DTPA (3,6,9-triaza-3,6,9-tris(carboxymethyl)-4-(ethoxybenzyl)-undecanedioic acid) from its Gd(III) complex and protocols for the preparation of its novel non-radioactive, i.e., natural Ga(III) as well as radioactive 68Ga complex. The ligand as well as the Ga(III) complex were characterized by nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry and elemental analysis. 68Ga was obtained by a standard elution method from a 68Ge/68Ga generator. Experiments to evaluate the 68Ga-labeling efficiency of EOB-DTPA at pH 3.8&#8211;4.0 were performed. Established analysis techniques radio TLC (thin layer chromatography) and radio HPLC (high performance liquid chromatography) were used to determine the radiochemical purity of the tracer. As a first investigation of the 68Ga tracers&#39; lipophilicity the n-octanol/water distribution coefficient of 68Ga species present in a pH 7.4 solution was determined by an extraction method. In vitro stability measurements of the tracer in various media at physiological pH were performed, revealing different rates of decomposition.

Investigations on the GaIII Complex of EOB-DTPA and Its 68Ga Radiolabeled Analogue

A procedure for the isolation of EOB-DTPA and subsequent complexation with natural Ga(III) and 68Ga is presented herein, as well as a thorough analysis of all compounds and investigations on labeling efficiency, in vitro stability and the n-octanol/water distribution coefficient of the radiolabeled complex.

We demonstrate a method for the isolation of EOB-DTPA (3,6,9-triaza-3,6,9-tris(carboxymethyl)-4-(ethoxybenzyl)-undecanedioic acid) from its Gd(III) ...

Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a free-radical polymerization strategy to enable the modulation of the nanotube surface properties and produce supramolecular self-assembly of the nanostructures. First, a selective hydroxylation of the pristine nanotubes through a biphasic catalytically mediated oxidation reaction creates superficially distributed reactive sites at the sidewalls. The latter reactive sites are subsequently modified with methacrylic moieties using a silylated methacrylic precursor to create polymerizable sites. Those polymerizable groups can address further polymerization of styrene to produce a hybrid nanomaterial containing PS chains grafted to the nanotube sidewalls. The polymer-graft content, amount of silylated methacrylic moieties introduced and hydroxylation modification of the nanotubes are identified and quantified by Thermogravimetric Analysis (TGA). The presence of reactive functional groups hydroxyl and silylated methacrylate are confirmed by Fourier Transform Infrared Spectroscopy (FT-IR). Polystyrene-grafted carbon nanotube solutions in tetrahydrofuran (THF) provide wall-to-wall collinearly self-assembled nanotubes when cast samples are analyzed by transmission electron microscopy (TEM). Those self-assemblies are not obtained when suitable blanks are similarly cast from analogous solutions containing non-grafted counterparts. Therefore, this method enables the modification of the nanotube anisotropic patchiness at the sidewalls which results into spontaneous auto-organization at the nanoscale.

A procedure for the synthesis of polystyrene-grafted multiwalled carbon nanotubes using successive chemical modification steps to selectively introduce the polymer chains to the sidewalls and their self-assembly via anisotropic patchiness is presented.

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Solvothermal Synthesis of MIL-96 and UiO-66-NH2 on Atomic Layer Deposited Metal Oxide Coatings on Fiber Mats

Metal-organic frameworks (MOFs), which contain reactive metal clusters and organic ligands allowing for large porosities and surface areas, have proven effective in gas adsorption, separations, and catalysis. MOFs are most commonly synthesized as bulk powder, requiring additional processes to adhere them to functional devices and fabrics that risk decreasing the powder porosity and adsorption capacity. Here, we demonstrate a method of first coating fabrics with metal oxide films using atomic layer deposition (ALD). This process creates conformal films of controllable thickness on each fiber, while providing a more reactive surface for MOF nucleation. By submerging the ALD coated fabric in solution during solvothermal MOF synthesis, the MOFs create a conformal, well-adhered coating on the fibers, resulting in a MOF-functionalized fabric, without additional adhesion materials that may block MOF pores and functional sites. Here we demonstrate two solvothermal synthesis methods. First, we form a MIL-96(Al) layer on polypropylene fibers using synthetic conditions that convert the metal oxide to MOF. Using initial inorganic films of varying thicknesses, diffusion of the organic linker into the inorganic allows us to control the extent of MOF loading on the fabric. Second, we perform a solvothermal synthesis of UiO-66-NH2 in which the MOF nucleates on the conformal metal oxide coating on polyamide-6 (PA-6) fibers, thereby producing a uniform and conformal thin film of MOF on the fabric. The resulting materials can be directly incorporated into filter devices or protective clothing and eliminate the maladroit qualities of loose powder.

Solvothermal Synthesis of MIL-96 and UiO-66-NH2 on Atomic Layer Deposited Metal Oxide Coatings on Fiber Mats

Metal-organic frameworks are effective in gas storage and heterogeneous catalysis, but typical synthesis methods result in loose powders that are difficult to incorporate into smart materials. We demonstrate a method of first coating fabrics with ALD metal oxides, resulting in conformal films of MOF on the fabrics during solvothermal synthesis.

Metal-organic frameworks (MOFs), which contain reactive metal clusters and organic ligands allowing for large porosities and surface areas, have proven ...

Negative Additive Manufacturing of Complex Shaped Boron Carbides

Boron carbide (B4C) is one of the hardest materials in existence. However, this attractive property also limits its machineability into complex shapes for high wear, high hardness, and lightweight material applications such as armors. To overcome this challenge, negative additive manufacturing (AM) is employed to produce complex geometries of boron carbides at various length scales. Negative AM first involves gelcasting a suspension into a 3D-printed plastic mold. The mold is then dissolved away, leaving behind a green body as a negative copy. Resorcinol-formaldehyde (RF) is used as a novel gelling agent because unlike traditional hydrogels, there is little to no shrinkage, which allows for extremely complex molds to be used. Furthermore, this gelling agent can be pyrolyzed to leave behind ~50 wt% carbon, which is a highly effective sintering aid for B4C. Due to this highly homogenous distribution of in situ carbon within the B4C matrix, less than 2% porosity can be achieved after sintering. This protocol highlights in detail the methodology for creating near fully dense boron carbide parts with highly complex geometries.

A method called negative additive manufacturing is used to produce near fully dense complex shaped boron carbide parts of various length scales. This technique is possible via the formulation of a novel suspension involving resorcinol-formaldehyde as a unique gelling agent that leaves behind a homogenous carbon sintering aid after pyrolysis.

Boron carbide (B4C) is one of the hardest materials in existence. However, this attractive property also limits its machineability into complex shapes for ...