bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Graphene and "Beyond" Graphene-Enabled Bio-Nano Hybrids for Programmable Chemical Detection
Authors: Johnson a T Charlie
Published: February 2020

We have explored all-electronic chemical detectors based on bio-nano hybrids, where the biomolecule (DNA or protein) provides chemical recognition and a carbon nanotube (NT), graphene, or monolayer molybdenum disulfide (MoS2) transistor enables electronic readout. Building on rapid advances in nanomaterials research and biomolecular engineering, this sensor class represents a promising approach towards sensitive and selective detection of liquid- and vapor-phase anayltes. Coupling chemistries have been developed that allow for creation of nanoelectronic and/or nanophotonic interfaces to a variety of different proteins including wild types and variants engineered for use in nanotechnology. Such bio-nano hybrids enable detection of protein cancer biomarkers, antigen from various pathogens, and small molecule targets at concentrations ~ 1 pg/mL. Single stranded DNA can be coupled to nanotubes and graphene through non-covalent functionalization and then used for its chemical recognition for small molecule analytes rather than recognition of complementary DNA. Vapor sensors based on this approach are able to discriminate between highly similar compounds such as enantiomers and very similar complex vapor mixtures characteristic of humans. More recently we have shown the promise of this system for diagnosis of disease based on volatile biomarkers. The chemical responses of this sensor class vary with the based sequence of the DNA, making this a promising pathway towards a system for machine olfaction. The work was supported by the National Science Foundation, Lockheed Martin, the Air Force Research Laboratory, Intel, and DARPA.
Covalent Functionalization of Graphene on Surfaces and in Solution
Authors: Hirsch Andreas
Published: February 2020

We will present a series of new covalent functionalization sequences for graphene. For this purpose we reductively actived graphite. The resulting gaphenides were treated with electrophiles such as diazonium compounds in solution or on surfaces. This allowed for the first time to investigate the topicity (monotopic versus ditopic) of covalent graphene functionalization. The reaction products were fully characterized using state-of-the-art methods such as Scanning-Raman-Microscopy (SRM), TGA/MS/GC and electron microscopy.
(Invited) Functionalized Pi-Extended porphyrins As Sensitizer for Dye-Sensitized Solar Cells
Authors: Wang Hong , Kerr Lei , Jinadasa R. G. Waruna , Li Bihong , Schmitz Benjamin , Matus Alex , Hu Yi
Published: February 2020

Significant progress has been made on dye-sensitized solar cells sensitized by push-pull porphyrins in recent years.1-3 Through installing push-pull groups at porphyrin meso-positions, exceptionally high power conversion efficiencies have been achieved.4, 5 In this work, we present the recent progress on synthesis and characterization of new classes of functionalized pi-extended porphyrins, and their application as sensitized for dye-sensitized solar cells. We show that through installing push-pull groups at the porphyrin beta-positions, both the UV-Vis absorption bands and fluorescence emission bands are much red-shifted and broadened relative to those of the porphyrins bearing no push-pull groups. These porphyrins show moderate to high power conversion efficiencies. In addition, anchoring group effects will also be discussed in this presentation. The design and synthesis of these organic materials take advantage of the chemistry of bromoporphyrins6-9 and a palladium (0) catalyzed cascade reaction developed in the Wang group.10
The electronic and optical properties of these p-extended porphyrins were measured using UV-Vis spectroscopy, life-time and steady state fluorescence spectroscopy, and cyclic voltammetry. DFT calculations were also performed for these porphyrins.

Reference

1.    T. Higashino and H. Imahori, Dalton Trans., 2015, 44, 448-463.

2.    M. Urbani, M. Gratzel, M. K. Nazeeruddin and T. Torres, Chem. Rev., 2014, 114, 12330-12396.

3.    L. L. Li and E. W. Diau, Chem. Soc. Rev., 2013, 42, 291-304.

4.    A. Yella, H.-W. Lee, H. N. Tsao, C. Yi, A. K. Chandiran, M. K. Nazeeruddin, E. W.-G. Diau, C.-Y. Yeh, S. M. Zakeeruddin and M. Grätzel, Science, 2011, 334, 629-634.

5.    S. Mathew, A. Yella, P. Gao, R. Humphry-Baker, B. F. Curchod, N. Ashari-Astani, I. Tavernelli, U. Rothlisberger, M. K. Nazeeruddin and M. Gratzel, Nat. Chem., 2014, 6, 242-247.

6.    L. Jaquinod, R. G. Khoury, K. M. Shea and K. M. Smith, Tetrahedron, 1999, 55, 13151–13158.

7.    L. Jaquinod, R. G. Khoury, K. M. Shea and K. M. Smith, Tetrahedron, 1999, 55, 13151-13158.

8.    O. Siri and K. M. Smith, Tetrahedron Lett., 2003, 44, 6103-6105.

9.    M. J. Crossley, P. L. Burn, S. S. Chew, F. B. Cuttance and I. A. Newsom, J. Chem. Soc., Chem. Commun, 1991, 1564-1566.

10.   R. Deshpande, L. Jiang, G. Schmidt, J. Rakovan, X. Wang, K. Wheeler and H. Wang, Org. Lett., 2009, 11, 4251-4253.

Figure 1
(Invited) The Reactivity and Mechanistic Studies of Group 14 Corrole Complexes
Authors: Fu Xuefeng
Published: February 2020

The discoveries of facile syntheses of meso-aryl substituted corroles in 1999 triggered the revival of the chemistry of corroles. A variety of main group and transition metal elements were inserted into the corrole ring and some of the complexes show similar or superior properties to the related porphyrin complexes. The corrole germanium hydride showed unusual high reactivity with aldehydes, olefins and alkyl halides to form corrole germanium α-hydroxy alkyl and alkyl complexes. More importantly, the efficient photo-activation of N-H bond by TEMPO-Ge corrole complexes was observed and the mechanism was investigated based on EPR analysis.   The reactivity of Sn corrole was also studied. Activation of N–H bonds with silicon and its low-valent heavier congeners typically proceeds via 2 electron pathways: i) a direct oxidative addition of the N–H bond to the low-valent metal center or ii) a metal-ligand cooperative process. Light-promoted N–H bond activation by main group element radicals has thus far rarely been encountered, but provides an attractive strategy to activate amines with lower activation energies. We observed the light-driven activation of N–H bonds by an organo-germanium corrole complex [(TPFC)Ge(TEMPO)] (TPFC = tris(pentafluorophenyl)corrole, TEMPO = (2,2,6,6-tetramethylpiperidin-1-yl)oxyl) involving a radical pathway to form germanium amides in high yields at room temperature.
(Invited) [30]Trithiadodecaazahexaphyrins: Synthesis and Properties
Authors: Trukhina Olga , Islyaikin Mikhail , Rodriguez-Morgade M. Salome , Torres Tomas , Ivanov Eugeni , Caballero Esmeralda
Published: February 2020

[30]Trithiadodecaazahexaphyrins are 30 π-electron planar analogues of hexaphyrins that have received a special attention in a relation to their non-aromatic nature. Exceptional chemical versatility and architectural flexibility of these macrocycles allow modification of their peryphery  as well as an insertion of up to three transition metals within their central cavity and – as a result – the fine-tuning of their physical and chemical properties. Owing to their intense absorption in the visible region of the solar spectrum, complementary to that of porphyrins and phthalocyanines, high extinction coefficients, and high optical and thermal stabilities , thiadiazoloporphyrinoids evolve as promising light-harvesting building blocks, complementary to tetrapyrrolic macrocycles and carbon nanostructures such as fullerenes, carbon nanotubes and graphene. In this communication a brief summary of our recent work in this area is given.
(Invited) Predicting the Degree of Aromaticity of Novel Porphyrinoid Compounds
Authors: Fliegl Heike
Published: February 2020

Electronic and spectroscopic properties of porphyrinoid macrocycles are, to a large extent, determined by the number of π-electrons participating in the conjugation network. Full control of the number of π-electrons implies full control of the aromatic or antiaromatic character of the molecule. To achieve this, knowledge about the electron delocalization pathways within a molecule is essential. Experimentally, these pathways are not easily accessible. Therefore theoretical studies are necessary to complement experiments that aim at systematically synthesizing porphyrinoids with distinct properties.

A computational approach to achieve this is the gauge including magnetically induced current density method (GIMIC). GIMIC is a independent program that is used for the calculation of magnetically induced current densities using London orbitals.[1, 2] Numerical integration of the current flow around molecular rings and along selected chemical bonds can be used for determining current pathways and the degree of aromaticity of various molecules according to the magnetic criterion.[3,4] In my talk I am going to present the GIMIC method and briefly discuss the idea behind it. I will illustrate what type of information is accessible through current density studies. Some very recent results on carbaporphyrinoids will be highlighted showing the potential and the challenges of the method.[5,6]

References:

[1] J. Jusélius, D. Sundholm and J. Gauss, J. Chem. Phys., 121, 3952-3963 (2004).

[2] H. Fliegl, S. Taubert, O. Lehtonen and D. Sundholm, Phys. Chem. Chem. Phys., 13, 20500- 20518 (2011).

[3] R. Valiev, H. Fliegl and D. Sundholm, Phys. Chem. Chem. Phys., 16, 11010-11016 (2014).

[4] H. Fliegl, F. Pichierri and D. Sundholm, J. Phys. Chem. A, 119, 2344-2350 (2015).

[5] R. Valiev, H. Fliegl and D. Sundholm, J. Phys. Chem. A, 119, 1201-1207 (2015).

[6] R. Valiev, H. Fliegl and D. Sundholm, Phys. Chem. Chem. Phys., 17, 14215-14222 (2015).
(Invited) Interactions of Antioxidant-Substituted Macrocycles
Authors: Hill Jonathan P. , Payne Daniel , Matsushita Yoshitaka , Jin Shangbin , Labuta Jan , Ariga Katsuhiko
Published: February 2020

Porphyrins substituted with antioxidant 2,6-di-tert-butylphenol substituents have been shown to exhibit different conformations based on the oxidation state of those substituents leading to the oxoporphyrinogens.1,2 We have attempted to apply this feature in numerous other macrocyclic and non-macrocyclic chromophores in order to assess any possibility for controlling molecular morphology. These attempts have included phthalocyanines, triarylamines (TPA), hexaphenylbenzene (HPB) and resorcinarene. Here, we will describe the results of these investigations including highlighting the potential applications of different compounds obtained from the porphyrin system,3,4 synthesis and structure in the phthalocyanine,5 TPA and HPB systems,6 and an extensive crystallographic analysis of the resorcinarene system.7 We will also present spectroscopic aspects of these compounds including how they interact with some analytes, and electrochemical data illustrating coupling between structures and the oxidation states of the compounds.

References: (1) F. D’Souza, N. K. Subbaiyan, Y. Xie, J. P. Hill, K. Ariga, K. Ohkubo, S. Fukuzumi, J. Am. Chem. Soc. (2009) 131, 16138–16146. (2) J. P. Hill, I. J. Hewitt, C. E. Anson, A. K. Powell, A. L. McCarthy, P. Karr, M. Zandler, F. D’Souza, J. Org. Chem. (2004) 69, 5861–5869. (3) S. Ishihara, J. Labuta, T. Šikorský, J. V. Burda, N. Okamoto, H. Abe, K. Ariga, J. P. Hill, Chem. Commun. (2012) 48, 3933–3935 (4) A. Shundo, J. Labuta, J. P. Hill, S. Ishihara, K. Ariga, J. Am. Chem. Soc. (2009) 131, 9494–9495; J. Labuta, S. Ishihara, A. Shundo, S. Arai, S. Takeoka, K. Ariga, J. P. Hill, Chem. Eur. J. (2011) 17, 3558–3561.  (5) J. P. Hill, N. K. Subbaiyan, F. D’Souza, Y. Xie,
 
S. Sahu, N. M. Sanchez-Ballester, K. Ariga, Chem. Commun. (2012) 48, 3951–3953. (6) S. Jin, J. P. Hill, F. D'Souza, K. Ariga, (2016) in press. (7) D. Payne, J. P. Hill, F. D'Souza, K. Ariga, (2016) in press.

Figure. X-ray crystal structure of antioxidant-substituted resorcinarene.

Figure 1
(Invited) 'totem' C2-Symmetrical Iron(III) Porphyrin Complexes to Stereoselectively Promote the Alkene Cyclopropanation
Authors: Gallo Emma , Intrieri Daniela , Carminati Daniela Maria , Toma Lucio , Le Gac Stéphane , Boitrel Bernard
Published: February 2020

The stereoselective synthesis of cyclopropanes is an important issue in synthetic chemistry due to the relevance of these three-member carbon rings which often represent the active part in biological and/or pharmaceutical compounds.1,2 The one pot reaction of diazo compounds with alkenes represents a sustainable methodology to achieve cyclopropanes due to the formation of N2 as the only stoichiometric by-product. The reaction is efficiently catalysed by metal porphyrins which promote the synthesis of cyclopropanes with excellent diastereo- and enantioselectivities. Considering the importance in developing eco-friendly catalytic procedures, we are currently studying the catalytic activity of iron porphyrins which display a cheap, efficient and low toxic metal centre.

The two iron complexes 1Fe and 2Fe are good catalysts for the alkene cyclopropanation and both have one C2 axis within the porphyrin plane and exhibit an open space on each side for the substrate access. Complex 1Fe displays a pre-organized structure which was responsible for excellent trans-diastereoselectivities (94-99%) in alkene cyclopropanations while the presence of chiral moieties in 2Fe allowed to perform the reactions with also a very good enantioselectivity (up to 87%).2

Experimental data disclosed that each ‘totem’ portion of 2Fe has a specific catalytic role: i) the porphyrin core containing the active iron centre is in charge to activate the diazo compound; ii) benzylic moieties are responsible for the reaction diasteroselectivity and iii) the two chiral binaphthyl groups allow the enantioselective synthesis of cyclopropanes.

The study of the reaction scope revealed that both 1Fe and 2Fe catalysts were active in promoting the cyclopropanation of several olefins by differently substituted diazo compounds.

References

1. a) C. A. Carson, M. A. Kerr, Chem. Soc. Rev.
2009, 38, 3051-3060. b) A. K. Kumar, Int. J. Pharm. Pharm. Sci. 2013, 5, 467-472.

2. D. Intrieri, S. Le Gac, A. Caselli, E. Rose, B. Boitrel, E. Gallo, Chem. Commun. 2014, 50, 1811-1813.

Figure 1
(Invited) Catalytic Activity of Vitamin B12 under Light Irradiation
Authors: Gryko Dorota
Published: February 2020

Vitamin B12 is a highly functionalized tetrapyrrolic compound bearing a central cobalt ion. It has been examined as an oral delivery vehicle for therapeutic agents, as an artificial enzyme and more importantly as a catalyst for various organic reactions.[1], [2] Like most great ideas vitamin B12 catalysis was inspired by the ultimate chemist Nature, as methylcobalamin and adenosylcobalamin are involved in numerous biocatalytic reactions including isomerization, methylation and dehalogenation.[2] This type of catalysis has been successfully translated into the laboratory and used in a small collection of reactions.[3] The advantage of using vitamin B12 lays in the complete stability of the central cobalt ion, whereas most catalytic reactions require the addition of toxic metals plus complex ligands into a cocktail of reagents, vitamin B12 in itself is a package deal. Furthermore, it has been well documented that the reaction mechanism usually follows a radical pathway, bringing a new dimension to this already interesting field.

We have shown that vitamin B12 is an effective catalyst for not only C-C bond forming reaction but also cleavage of C-O bonds under light irradiation.

Reference:

1.     Banerjee, R. Chemistry and Biochemistry of B12, John Wiley & Sons, Inc, 1999

2.     K. ó Proinsias, M. Giedyk, D. Gryko, Chem. Soc. Rev.
2013, 42, 6605-6619.

3.  Giedyk, M.; Fedosov, S.; Gryko, D. Chem.
Commun.
2014, 50, 4674-4676.

4. a) Shimakoshi, H.; Nishi, M.; Tanaka, A.; Chikama, K.; Hiseada, Y. Chem. Commun. 2011, 47, 6548-6550. b) K. Tahara, Y. Hisaeda, Green Chem.
2011, 13, 558-561. H. Shimakoshi, L. Li, M. Nishi, Y. Hisaeda, Chem. Commun.
2011, 47, 10921-10923.

Figure 1
(Invited) Self-Assembled Molecular Materials Based on Subphthalocyanines
Authors: Torres Tomas , Mayoral Maria J , Guilleme Julia , González-Rodríguez David , Lavarda Giulia , Guzman David , Medina Diana Paola , Revuelta Miguel Angel
Published: February 2020

Columnar nanostructures and liquid crystals are an important class of self-assembled organic materials that are making great impact on several optoelectronic technologies like transistors, solar cells, ferroelectric switches or light-emitting diodes. These materials are typically produced by the ordered stacking of functional molecules with a discotic shape. We have here studied related assemblies from a unique class of molecules, Subphthalocyanines, having instead a rigid conical shape and strong axial dipole moment. In solution, these molecules organize into non-centrosymmetric supramolecular columnar polymers that show intriguing dual-mode self-assembly and chiral self-sorting processes, as a result of the intrinsic monomer chirality. In condensed phases, the generation of liquid crystalline materials that can be efficiently aligned in the presence of electric fields and that exhibit permanent or switchable net polarization is observed. This is a novel and appealing attribute that may have important implications in, for instance, technologies that require an efficient directional transport of charges or memory devices combining ferroelectric and semiconducting properties.
(Invited) Functionalizing P-Extended Porphyrins
Authors: Wang Hong , Jinadasa R. G. Waruna , Fang Yuanyuan , Kumar Siddhartha , Kadish Karl M. , Hu Yi
Published: February 2020

Pi-extended porphyrins possess an unique set of photophysical and optoelectronic properties due to their extended pi structure. Pi-extended porphyrins promise broad application in various areas ranging from biomedicine to organic electronics due to their much broadened and red-shifted UV-Vis absorption and emision bands..1-4 In this presentation, we report methodolgy development for the synthesis and functionalization of several series of pi-extended porphyrins including push-pull dibenzoporphyrins,5, 6 A2B2
push-pull tetrabenzoporphyrins, and porphyrins oligomers linked through porphyrin beta-positions. New push (electron-donating groups) and pull (electron-withdrawing) groups were introduced at the porphyrin beta-positions and push-pull effects were studied. The electronic and optical properties of these p-extended porphyrins were measured using UV-Vis spectroscopy, steady state fluorescence spectroscopy, and cyclic voltammetry. DFT calculations were also performed for these porphyrins.

Reference

1.    A. V. Cheprakov and M. A. Filatov, J. Porphyrins Phthalocyanines, 2009, 13, 291-303.

2.    C. M. Carvalho, T. J. Brocksom and K. T. de Oliveira, Chem. Soc. Rev., 2013, 42, 3302-3317.

3.    N. Ono, H. Yamada and T. Okujima, in The Porphyrin Handbook, eds. K. M. Kadish, K. M. Smith and R. Guilard, World Scientific 5 Toh Tuck Link, Singapore, 2010, vol. 2, ch. 7.

4.    T. Tanaka and A. Osuka, Chem. Soc. Rev., 2015, 44, 943-969.

5.    R. G. W. Jinadasa, Y. Fang, Y. Deng, R. Deshpande, X. Jiang, K. M. Kadish and H. Wang, RSC Adv., 2015, 51489-51492.

6.    R. G. W. Jinadasa, Y. Fang, S. Kumar, A. J. Osinski, X. Jiang, C. J. Ziegler, K. M. Kadish and H. Wang, J. Org. Chem., 2015, ASAP.

Figure 1
(Invited) Synthesis and Characterization of Photoactive Porphyrin Electropolymers
Authors: Otero Luis Alberto
Published: February 2020

The design and development of new polymeric functional material for application in organic optoelectronic devices, like polymer solar cells, is one of the most active areas of research, mainly due to the continuous search for low cost renewable energy sources. Flexibility, solution processability, and short energy payback time, are among the very important characteristics of the organic based materials that make possible their application in large area devices. However, despite the facts that high power conversion efficiencies have been attained with bulk heterojunction structures, and that the potentiality of the organic photovoltaic technology is still huge, to date industrial production and large scale commercialization have not been achieved, a major issue being the transfer of the efficiencies obtained on small area cells to large area modules. Thus, the development of new polymeric materials and devices construction methods are still necessary, in order to find procedures that allow the implementation of this relevant technology.

            One of the principal difficulties that the use of organic polymers in electronics has to face is the ﬁlm deposition methodology over the conducting or semiconducting contacts. The most common approaches rely on thermal evaporation and solution-processing methods. However, thermal evaporation requires materials with adequate sublimation capability and thermal stability, properties that are difficult to reach in polymers. Also, solution processes, such as dip - or spin - coating methodologies, require polymeric materials with intrinsic high solubility. On the contrary, electropolymerization of suitable photoelectroactive monomers allows the synthesis and formation of polymeric ﬁlms in one step, with the possibility to get control over pattern and thickness, two very important aspects in the implantation of industrial processes. In the last years we developed porphyrin polymeric materials, produced by electrochemical methods. These materials exhibited photovoltaic and electrochromic properties. The monomers were planned with the aim to achieve their polymerization through dimerization of the electrochemically generated tryphenyl amine and/or carbazole radical cations, giving rise to tetraphenylbenzidine and/or dicarbazole substructures with hole transport capability. These polymers demonstrate their capacity for the generation of photoinduced charge separated states, with light absorption in a broad region of the visible spectrum, and hold the potentiality for their application in the development of optoelectronic devices.
FRET-Based Ratiometric Detection of Metal Ions
Authors: Bian Yongzhong , Zhu Mengliang , Zhang Dongli , Lu Wenxin , Zhang Jinghui , Jiang Jianzhuang
Published: February 2020

Fluorescent sensors for detecting transition- and heavy-metal ions in environmental and biological systems have received considerable attention. In comparison with single emission intensity-based “turn-off” or “turn-on” sensors, ratiometric sensors can afford self-calibration by dual-channel detection and thus perform precise analyses against various environmental and instrumental factors. One of the most frequently applied mechanisms for ratiometric sensing is the binding-induced modulating of intramolecular fluorescence resonance energy transfer (FRET), which is highly dependent on the distance between the donor and acceptor, the overlap integral between the donor emission and acceptor absorption, and the relative orientation of the transition dipoles. Hence the binding-induced changes of the spatial and electronic structure can effectively modulate the FRET efficiency within a donor-acceptor system, consequently leading to change in the fluorescence intensity of the donor and acceptor.

In order to develop heavy-metal ion sensors, we have proposed a new strategy for ratiometric fluorescent detection that is based on the rational integration of two sensing mechanisms of a binding-induced modulating of FRET efficiency coupled with a metal-chelating quenching of fluorescence. Synergistic coupling of these two functions leads to exceptionally large change in the emission ratio, thus allowing for ratiometric detecting of metal ions with improved sensitivity. As proof-of-concepts, a BODIPY-porphyrin dyad (1) and a series of phthalocyanine-porphyrin(Zn) hetero-oligomers (2-4) have been designed for ratiometric fluorescent detection, which show excellent selectivity and sensitivity toward Ag+ and Pb2+ respectively.

Figure
1. Ratiometric fluorescent detection of Ag+ by FRET-based BODIPY-porphyrin dyad (1).

References

1. Zhu, M.; Bian Y. et al. Inorg. Chem., 2014, 53, 12186-12190.

2. Zhang, D.; Bian Y. et al. 2015, submitted. 

Figure 1
Synthesis of Oxide-Anchored Graphene Sheets By Electrochemical Exfoliation
Authors: Lai Chun-Han , Zhou Xin , Kim Hyung-Seok , Dunn Bruce
Published: February 2020

Niobium oxide/carbon (Nb2O5/C) composites were synthesized in a one-pot process by combining electrochemical exfoliation of graphite with anodic deposition of niobium oxide. The purpose of this study is to develop an electrolyte system that includes a precursor for oxide deposition as well as graphite exfoliation agents. We anticipated that the oxide coating on graphene morphology would provide excellent ‘wiring’ to the transition metal oxide and enable redox reactions to occur at high rates. For electrochemical exfoliation, sulfuric acid and oxalic acid have been commonly used to efficiently prepare high-quality graphene sheets in a large quantity. In the research reported here, various amounts of ammonium niobate oxalate hydrate (NH4NbO(C2O4)2-nH2O) were dissolved in 1M sulfuric acid and oxalic acid for a systematic study. A control system of 1M hydrochloric acid, a relatively weak exfoliation agent, was also investigated for comparison.

To understand the ion species in the electrolytes, Raman spectroscopy was used to determine the relative amount of the dissolved oxalatooxoniobate. The experimental setup consists of a high-purity graphite rod as the anode and a Pt foil as the cathode. Voltages of 5 to 10V were applied across the electrodes for 30 minutes. After that, the Nb2O5-anchored exfoliated carbons were collected, washed, and characterized by different techniques. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to image sample morphologies and perform elemental distribution, respectively. Thermogravimetric analysis (TGA) was used to quantify Nb2O5 and carbon contents and X-ray Diffraction (XRD) was used to identify Nb2O5phases. Raman spectroscopy was also used to determine carbon-carbon bonding quality while transmission electron microscopy (TEM) was used to image the oxide nanoparticle distribution on the carbon nanostructures.

The complex NbO(C2O4)2H2O− in sulfuric acid was successfully converted into Nb2O5 on the exfoliated graphene sheets. In contrast, NbO(C2O4)3
3- in oxalic acid prevented graphite from exfoliating by blocking the pathways for  intercalation and active sites for oxide growth. The Nb2O5/C composites obtained using the hydrochloric acid electrolyte exhibits a uniform coating of Nb2O5 on thin graphene layers (Figure 1). Finally, a mechanism for simultaneous deposition/exfoliation was proposed based on interactions between oxalatooxoniobate ions and graphite electrodes. The Nb2O5/C composites were tested for energy storage and exhibited good energy densities at high charge/discharge rates.

Figure 1
3D Carbon-MEMS a Potent Molecular Recognition Platform for the Detection of DNA Molecule
Authors: Rahman Md Mahfujur , Abd Hamid Sharifah Bee , Ibrahim Fatimah , Madou Marc J
Published: February 2020

Deoxyribonucleic acid (DNA) molecule is the building block which architects the genetic materials for development and functioning of most living organisms. The characteristics of the DNA molecule such as stability to the mechanical and thermal stress, universal presence in all tissue or cell and more informative with unique genetic code, makes it very useful for organisms species detection. Furthermore, recent discovery of the structural and functional properties of the DNA molecule extended its application for bio-imaging, bio-diagnostics and sensing for drug delivery. Thus a number of assays have been introduced for the detection of specific DNA target such as real-time polymerase chain reaction assay and molecular fluorophores labelled platforms, but those are suffering for high costing. Furthermore, traditional biological signal detection platform with two-dimensional (2D) patterns and 2D nature electrodes have the drawbacks of lower sensitivity. Microfabrication of 3D carbonaceous structures, carbon-microelectromechanical system (C-MEMS) based on the thermochemical decomposition of patterned organic photoresist at high temperatures in oxygen-free environment, draw recent attention for the detection of DNA. In comparison with fluorescence detection platform on 2D carbon micropatterns, 3D micro arrays not suffer from optical interferences obtained on oxidized silicon substrates. The architectural tools for 3D C-MEMS, such as lithography and pyrolysis facilitate to generate varied carbon structure with different crystallinity, size and shape. Furthermore, integration of certain nanomaterials such as grapheme, carbon nanotubes or nanofibers with C-MEMS can create high surface area for carbon microarray. Thus fabrication of the 3D carbon microarrays with higher surface area increases the loading capability of the biomolecule to improve the sensitivity and performance of the DNA detection platform.

Acknowledgement

This research is supported by University Malaya Flagship Grant project FL001A-14AET, MOSTI SF020-2014, and Transdisciplinary Research Grant Scheme (TRGS TR002A-2014) from Malaysian Ministry of Higher Education.
Carbon Nanotubes (CNTs) a Potent Nanoplatform for Biomolecular Sensing
Authors: Al Amin Mohammad , Rahman md Mahfujur , Abd Hamid Sharifah Bee
Published: February 2020

Advanced of nanomaterials have opened up the probability and prospect for sensing of DNA molecules with higher sensitivity and selectivity. Nanomaterials based biosensors have received huge attention due to its unique physio-chemical properties and provide DNA sensing platform in the field of biodiagnostices analysis. It is increasingly important in molecular diagnostics, species authentication, pathogen detection, forensic investigation and environmental monitoring. Therefore, both the single-wall (SWCNTs) and multi-wall (MWCNTs) carbon nanotubes have exhibit its outstanding potentiality for bimolecular sensing because of its unique mechanical, thermal, optical, and electrical properties. Thus, an overview is described here about recent advancement of DNA sensing platform using carbon nanotubes (CNTs) biomaterials.

Acknowledgement

This research is supported by University Malaya Flagship Grant project FL001A-14AET, MOSTI SF020-2014, and Transdisciplinary Research Grant Scheme (TRGS TR002A-2014) from Malaysian Ministry of Higher Education.
Fabricating Carbon Nanofiber Electrodes with Embedded Iron Nanoparticles Using Block Copolymers Templates
Authors: Holmberg Sunshine , Ghazinejad Maziar , Madou Marc J
Published: February 2020

Due to its high thermal, mechanical and electrochemical stability and good conductivity, carbon is an attractive material for fabrication of many bioelectrochemical devices such as biosensors and biofuel cells. However, carbon’s inert nature makes it difficult to functionalize with biocatalysts; often requiring harsh chemical treatment, such as nitric acid oxidation, to attach reactive amines and carboxylic acids to its surface.

Alternatively, metal nanoparticles have been demonstrated to be efficient supports for biocatalysts functionalization. [1-3] Depositing metal nanoparticles on carbon electrodes by physical vapor deposition (PVD) is a viable means of functionalizing carbon electrodes with biocatalyst. However, PVD is an expensive and directional deposition method; this may result in poor surface coverage for 3D carbon electrodes, such as carbon nanofiber mesh electrodes.

It has been traditionally difficult to incorporate nanoparticles into carbon nanofibers by embedding them into the polymer precursors prior to pyrolysis, as most metallic nanoparticles will melt at the temperatures needed for carbon pyrolysis (>900 oC).

Recent studies, however, points toward a self-assembly approach for fabricating well organized layers of carbon loaded with arrays of platinum nanoparticles patterned by block-copolymers (BCP) templates. [4-6] Herein, we demonstrate an effective method for developing carbon nanofibers meshes embedded with iron nanoparticles, by incorporating a BCP self-assembly approach into our C-MEMS fabrication technique. The main phase of this hybrid method includes electrospinning iron-salt-loaded BCP into nanofiber meshes, and subsequently reducing the iron salts into iron nanoparticles prior to pyrolysis. This cost-effective process will pave the way for fabricating scalable advanced 3-D carbon electrodes that can be applied to biosensors and biofuel cells devices.

[1] Zhao, Xin, et al. "Polymer-supported nanocomposites for environmental application: a review." Chemical Engineering Journal 170.2 (2011): 381-394.

[2] Zayats, Maya, et al. "Biocatalytic growth of Au nanoparticles: from mechanistic aspects to biosensors design." Nano letters 5.1 (2005): 21-25.

[3] Wilner, Ofer I., et al. "Self-assembly of enzymes on DNA scaffolds: en route to biocatalytic cascades and the synthesis of metallic nanowires." Nano letters 9.5 (2009): 2040-2043.

[4] Park, Soojin, et al. "From nanorings to nanodots by patterning with block copolymers." Nano letters 8.6 (2008): 1667-1672.

[5] Park, Soojin, et al. "Macroscopic 10-terabit–per–square-inch arrays from block copolymers with lateral order." Science 323.5917 (2009): 1030-1033.

[6] Jang, Yu Jin, et al. "Nanostructured Metal/Carbon Hybrids for Electrocatalysis by Direct Carbonization of Inverse Micelle Multilayers." ACS nano 7.2 (2012): 1573-1582.
EIS Study on Corrosion Mechanisms of Steel Rebars in Concrete
Authors: Itagaki Masayuki , Soukura Masanori , Koike Taisuke , Okamoto Tatsuki , Tokieda Hiroyuki , Hoshi Yoshinao , Shitanda Isao , Kato Yoshitaka
Published: February 2020

The durability of steel-reinforced concrete is a serious problem that concerns the whole world. It is well known that the corrosion of steel rebar in concrete is strongly influenced by the conditions of cover concrete, namely, water absorption, neutralization and chloride ion permeation. There are some literatures regarding the electrochemical tests, which are mainly measurements of corrosion potential and polarization curves, to evaluate corrosion of rebar in concrete [1,2]. Sagues et al. [3] reported the operation of a macroscopic Kelvin Probe (KP) for contactless measurement of concrete surface potentials. Dawson et al. [4] applied an electrochemical impedance spectroscopy (EIS) to the investigation of corrosion of rebar in concrete because the charge transfer resistance can be determined from the impedance spectrum.

Figure 1 shows the scheme of Nyquist plot of electrochemical impedance of steel-reinforced concrete. For example, a capacitive loop related to the time constant of charge transfer resistance and electric double layer capacitance at rebar/concrete interface is observed in the low frequency range. The capacitive loop in the middle frequency range is related to the electric nature of rust or oxide layer formed on rebar surface [5].  McCarter et al. [6] reported that capacitive loop in the high frequency range originated form the dielectric property of concrete absorbing water. In this presentation, we introduce some configurations of electrodes (or probes, sensor) to measure an impedance spectrum of steel-reinforced concrete. And we will discuss the corrosion behavior of rebar in concrete by analyzing the conditions of concrete and rebar/concrete interface by EIS.

References:

[1] ASTM C 876-91 (Reapproved 1999): Standard Test Method for Half-Cell Potentials of Uncoated Reinforcing Steel in Concrete, Annual Book of ASTM standards, Vol. 03.02, pp. 457-462, 1999.

[2] M.J. Dugarte, A.A. Sagues, Corrosion, 70 (2014) 303-317.

[3] A.A. Sagues, M.T. Walsh, Corrosion Science, 56 (2012) 26-35.

[4] J. L. Dawson, L. M. Callow, K. Hladky and J. A. Richardson, Corrosion/78, No-125 (1978).

[5] J. M. Deus, B. Diaz, L. Freire and X. R. Novoa, Electrochimica Acta, 131 (2014) 106-115.

[6] W. J. McCarter and S. Garvin, J. Phys. D: Appl. Phys., 22 (1989) 1773-1776.

Figure 1
An in-Depth Analysis of Protective Coatings Via Combination of EIS and SDM Techniques in Single Run
Authors: Vyas Ritesh , Kubicsko Michael
Published: February 2020

While the coating industry relies on several techniques to test the quality of their coatings, in past few years, electrochemical impedance spectroscopy (EIS) has emerged out as one of the most effective methods to non-destructively analyze protective coatings. Stepwise dissolution measurement (SDM) is an improvement over the more primitive anodic accelerated dissolution technique (AAD). In this work, we test the corrosion properties of three different protective coating materials by combining EIS & SDM techniques in one run.  EIS is immediately applied on three separate samples, before and after the stepwise dissolution measurement (SDM) in single run. The resulting nonaggressive corrosion technique allows selective dissolution to take place making it possible to distinguish between good and bad corrosion behavior immediately.
Anti-Corrosion and Mechanical Property of Zinc Modified Nanocomposites
Authors: Fang Te-Hua , Lee Ching-Hui
Published: February 2020

In this study, anticorrosion/antibacterial composite coatings were producing by incorporating zinc nanoparticles in epoxy and hybrid resin. Corrosion performance of the nanocomposites coating was evaluated by applying these coatings on carbon steel substrate during sodium chloride salt-spray methods. Adhesion test, scanning electron microscopy (SEM), X-ray fluorescence (XRF), and energy-dispersive spectrometer (EDS) were employed to character these coated with nano-composite substrates. The results of salt spray test showed that nano-zinc in epoxy and hybrid resin could react with permeated oxygen, leading to the improvement of anticorrosion properties of the zinc nanocomposites with addition of desirable of zinc nanoparticles. The corroded area of Zn/epoxy samples more than 80% (without Zn nanoparticle) to less than 5%(3,000 ppm Zn nanoparticle) after 500 hours salt spray test. The bactericidal properties evaluation showed that the bactericidal ability of the Zn/Epoxy, Zn/Hybrid resin nanocomposites with at least 360 ppm of nano-zinc and increased with nano-Zn content remarkably. The corrosion resistant and antibacterial properties are improved with addition of zinc nanocomposites coatings.
Impedance-Based Monitoring of Corrosion Behaviors in Graphene-Coated Metallic Substrates: Effect of Atomic Layer Deposition of Oxide Materials
Authors: Choi Yoo-Jin , Kim Eui-Hyun , Seo Ki-Won , Kwon Kyoung-Woo , Hwang Jinha
Published: February 2020

The graphene materials can be applied as the protective layers of metallic materials against hostile conditions. However, the 2-dimensional graphene materials suffer from the high defect densities formed in the edges and boundaries of graphenes. The sophisticated control on defective sites is required to eliminate the possibility of preferential corrosion at those sites. In the current work, the 2-dimensional graphene materials were combined with atomic layer deposition of oxide materials in order to improve the corrosion resistance of metallic substrates against aggressive conditions. The presence of the graphene layer on copper foils hinders the dissolution of the metallic copper elements in the corrosive electrolyte where there is formed an interface between the ionic electrolyte and electronic graphene/copper materials. The atomic layer deposition of Al2O3 materials were performed onto the as-grown graphene materials which are formed on copper substrates. The anti-corrosive protection of graphene materials is enhanced through the defect-curing function of Al2O3 deposited through atomic layer deposition. Frequency-dependent impedance spectroscopy was employed in order to quantitatively monitor the quality of the graphene materials grown on metallic copper substrates without involving time-consuming transfer processes. The electrochemical impedance spectroscopy was combined with the Tafel analysis in association with the potentiodynamic measurements. The impedance-based quality control is demonstrated for optimized corrosion protection.
Corrosion of Engineering Alloys in Supercritical CO2
Authors: Karmiol Zachary , Rodriguez David , Summers Kodi , Chidambaram Dev
Published: February 2020

Introduction:

The properties of supercritical carbon dioxide (scCO2) have made it attractive in numerous industries and in a variety of applications [1-3]. The need for compatibility of materials with scCO2 has been identified as a stumbling block for even wider application in industry [4-6]. An expanded understanding of the corrosion characteristics of engineering alloys in scCO2 with various impurities will provide necessary information for increased utilization.

Experimental:

Experiments were conducted in an autoclave, lined with Teflon. The autoclave is capable of maintaining a temperature of up to 423K (150˚C). Materials studied include austenitic steels as well as nickel based alloys. Environment included scCO2, as well as scCO2 with impurities. The surface of the samples were characterized after exposure to scCO2 using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy.

 

Results:

Figure 1 shows Raman spectra obtained from Inconel 625 and stainless steel 316 exposed to scCO2. Only Inconel 625 has detectable Raman modes after exposure to scCO2 with saturated water vapor at 80°C. The corrosion performance of Inconel 625 and stainless steel 316 are observed with respect to their surface chemistry.

Figure 1: Raman spectra for both the austenitic steel SS316 and nickel based alloy I625 exposed to 80°C SCO2 with saturated water vapor. Spectra collected with 532nm laser.

Acknowledgements: This study was supported by the Department of Energy, under Contract DE-NE0008236, and Nuclear Regulatory Commission (NRC) under award NRC-HQ-11-G-38-0039.

References:

[1] A.P. Sánchez-Camargo, J.A. Mendiola, E. Ibáñez, M. Herrero, Supercritical Fluid Extraction, Reference Module in Chemistry, Molecular Sciences and Chemical Engineering, Elsevier, 2014.

[2] H. Taher, S. Al-Zuhair, A.H. Al-Marzouqi, Y. Haik, M. Farid, Biochemical Engineering Journal 90 (2014) 103-113.

[3] K.M. Krupka, K.J. Cantrell, B.P. McGrail, Thermodynamic Data for Geochemical Modeling of Carbonate Reactions Associated with CO2 Sequestration – Literature Review, Pacific Northwest National Laboratory, 2010.

[4] X. Han, M. Poliakoff, Chemical Society Reviews 41 (2012) 1428-1436.

[5] T. Furukawa, Y. Inagaki, M. Aritomi, Progress in Nuclear Energy 53 (2011) 1050-1055.

[6] O. Yevtushenko, Water Impact on Corrosion Resistance of Pipeline Steels in Circulating Supercritical CO2 with SO2- and NO2- Impurities.

Figure 1
Development of Electrochemical Methods for High Temperature Molten Fluoride Salt Systems
Authors: Carotti Francesco , Brichford Meredy , Scarlat Raluca
Published: February 2020

Molten salt processes were developed several decades ago as a promising technology for material processing and industrial process heat applications. This technology is still seen today as extremely suitable for thermal energy storage and power production. Liquid salts can indeed be considered legitimate candidates for several heat transfer applications thanks to favorable physical properties such as high boiling point, low vapor pressures, large specific heat, and large thermal conductivity.

In December 2015 a “Molten Salt Electrochemistry Short Course” was organized at University of Wisconsin Madison. The course was taught by Professor Digby MacDonald, a renowned expert in electrochemistry techniques for corrosion studies in aqueous environments. The course concentrated on the fundamentals of electrochemistry, with specific references to processes such as corrosion, electro-deposition, passivity and passivity breakdown, stress corrosion cracking, and corrosion fatigue. The course also included a discussion of the specialized techniques employed to study hydrogen in metals and carbon (graphite).

This paper will discuss the applicability of each of these electrochemistry techniques to molten fluoride salts and will provide an overview of the current status of these techniques in fluoride ionic liquids. The definition of a thermodynamically stable reference electrode (RE) has emerged as one of the critical points required to rigorously apply electrochemistry analytical techniques to fluoride salt systems. Therefore, this paper will review the fluoride molten salt RE designs developed in the 1960s and 1970s and in recent years. Additionally this paper will report designs and testing of the fluoride salt REs under development at University of Wisconsin -Madison.
The Development of Novel Sound-Absorbing and Anti-Corrosion Nanocomposite Coating
Authors: Huang Chien-Yu , Jhuang Gao-Shu , Lee Yueh-Lien
Published: February 2020

The effects of addition of graphene on the corrosion protection and acoustic absorption performance of PU coatings have been studied in this paper. The corrosion properties of the coatings were characterized by electrochemical impedance spectroscopy, polarization measurements, and salt spray testing. The acoustic absorption coefficient (α) was measured over the frequency range of 1–10 kHz by two-microphone impedance tube filled with water. The preliminary experimental results showed that PU/graphene nanocomposite coating exhibited a relatively high and stable impedance value during exposure to a 3.5 wt% NaCl for 168 hours, suggesting the presence of graphene can effectively improve corrosion resistance of the PU coating. Also, it was observed that PU/graphene nanocomposite coating had higher acoustic absorption coefficient (α) and exhibited good absorption performance in the frequency range of 5000 Hz and 10000 Hz as the graphene content was increased up to 0.2 wt%.