bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Synthesis of Porphyrin Oligomers and Porphyrinoids Via Suzuki-Miyaura Reaction
Authors: Song Jianxin , Wen Bin 
Published: February 2020

In view of multi-porphyrin arrays and new porphyrinoids, whih has potential applications in optoelectronic devices, sensors, photovoltaic devices, non-linear optical(NLO) materials, photodynamic therapy (PDT) pigments, light-harvesting models, and host-guest chemistry. Both the manipulation of interporphyrinic interaction and design of new structural porphyrinods are often essential to achieve desirable electronic and photophysical properties. Recently, the Osuka group developed a transition metal-catalyzed coupling reaction that has been proven to be very useful to construct multiporphyrinic systems. Till now we have adopted this strategy and prepared many heterocycles bridged β-to-β porphyrin arrays, including direct-bridged β-to-β porphyrin nanorings[
1
], earring porphyrins[
3
]. The experiment results indicated that the building blocks will remarkably affect the target molecules. As the bridge is thienylene, the main products is cyclic dimer, trimer, when the bridge is pyridylene, there are trace cyclic products are obtained. when the bridge is free base or Zn(II) porphyrin, bigger loop are formed, while Ni(II)porphyrin is used, the products is much simple. As to synthesis of porphyrin nanobarrel, if the porphyrin monomer is free base or Zn(II) porphyrin, no porphyrin barrel is obtained, which means that only ruffled Ni(II)porphyrin monomers can be used to synthesis porphyrin barrels. Synthesis of direct linked porphyrin nanorings is affected by the meso-substituent on porphyrin, when the substituent is aryl, only trimer and twinned pentamer can be prepared, when the substituent is alkyl, tetramer and twinned heptamer can be obtained.The photophysical study revealed that these porphyrin arrays and porphyrinoids exhibit either longer fluorescent lifetime, larger two photon absorption values or Near-infrared absorptions. Some new porphyrin arrays or porphyrinnoids recently have been constructed through Pd-catalyzed cross-coupling reactions (Figure 1), further study on their properties is underway in our lab.
Figure 1. Crystals of earring porphyrins and multi-porphyrin arrays
References
1. H. Cai, K. Fujimoto, J. M. Lim, C. Wang, W. Huang, Y. Rao, S. Zhang, H. Shi, B. Yin, B. Chen, M. Ma, J. Song, D. Kim, and A. Osuka,
Angew. Chem. Int. Ed
., 2014, 51, 11088-11091.
2.H. Huang, S.-K. Lee, Y. M. Sung, F. Peng, B. Yin, M. Ma, B. Chen, S. Liu, S. R. Kirk, D. Kim, and J. Song,
Chem. Eur. J.
, 2015, 21, 15328-15338.
3. Y. Rao, T. Kim, K. H. Park, F. Peng, L. Liu, Y. Liu, B. Wen, S. Liu, S. R. Kirk, L. Wu, B. Chen, M. Ma, M. Zhou, B. Yin, Y. Zhang, D. Kim, and J. Song,
Angew. Chem. Int. Ed

.
2016, 55, 6438-6442

Figure 1
Tuning the Electrocatalytic Activity of Iron Phthalocyanines for O2 Reduction By the Pull Effect of the Pyridium Axial Ligands
Authors: Zagal Jose H 
Published: February 2020

A. Pizarro1, G. Abarca2, J. H. Zagal1, J. F. Silva1, F. Bernardi3, Cristian Gutiérrez-Cerón3, M. Caroli1, Diego Cortés-Arriagada 4, Rubén Oñate, Ingrid Ponce1

1 Facultad de Química y Biología, Universidad de Santiago de Chile. Avenida Libertador Bernardo O’Higgins 3363, Estación Central, Santiago, Chile. 2 Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, Porto Alegre, 91501-970, RS, Brazil. Institute of Physics, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, Porto Alegre, 91501-970, RS, Brazil. 3 Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile). 4 Laboratorio de Química Teórica Computacional (QTC), Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Macul, Santiago 9900087
Corresponding Author: jose.zagal@usach.cl
We have been able to tune the electrocatalytic activity of iron phthalocyanine (FePc) and iron hexadodecachlorophthalocyanine (16(Cl)FePc) for the oxygen reduction reaction (ORR) by the “pull effect” of pyridinium molecules, which play both the role of molecular anchors and also of and axial ligand for FePc. Pull effect is caused by the positive charge located on the core pyridinium. We have explored the influence of the core positions (Up or Down), in two structural pyridiniums isomers on the activity for the RRO of FePc and 16(Cl)FePc. Of all self-assembled systems tested, the ORR catalytic activity was highest for Au(111)/pyridinium-Up/FePc system. XPS measurements and DFT calculations showed that is possible to tune the FePc-N(Pyridiniums)
and Fe-O2
binding energies, by changing the core positions and affecting “pull effect” in pyridiniums, this has a direct effect on the activity of FePcs. Plot of activity as (log I)E versus the calculated Fe-O2
binding energies gives a volcano correlation indicating that an optimum binding energy of O2 with the Fe center provides the highest activity in agreement with previous findings [1] using MN4s adsorbed on graphite.
Acknowledgements: The authors are grateful to PAI-CONICYT 79150041. Fondecyt 1140192, C.G-C. Fondecyt Postdoctoral Project 3150674. D.C-A thanks ICM grant #120082. Powered@NLHPC: NLHPC (ECM-02). Millennium Project RC120001, Fondecyt 1140199, and Dicyt-USACH, LNLS (Brazil) for the use of beamline (SXS - 18986).
References:
1. Zagal, J. H.; Koper, M. T. M. Angew. Chemie Int. Ed.
2016, 55 (47), 14510–14521.

Figure 1
Electrochemical Studies of a Redox Responsive 4 H-Bond Array Capable of Self-Dimerization
Authors: Darzi Ghazwan M , Smith Diane K. 
Published: February 2020

Supramolecular structures can change in response to external signals, such as change in pH, temperature, or voltage of an electrode. This is important for many applications such as self-healing polymers and gels, triggered release of entrapped molecules for drug delivery, and smart material. Ureidopyrimidinone (UPy) array with an alkyl-pyridinium (RP) redox center has been synthesized for this study. This array prefers the tautomer that presents an ADAD H-bond motif in the starting oxidation state. Due to electrostatic repulsions and unfavorable secondary H-bond interactions, this motif would form a dimer with relatively weak H-bonding. Upon 2e- reduction, where 1e- is gained per R-pyridinium redox center, the H-bond strength should increase due to the loss of the repulsive charges, making the nitrogen a stronger hydrogen acceptor. Because the nitrogen is now a better hydrogen acceptor, there could be a possibility of an intermolecular proton transfer. This would encourage the tautomer to have an AADD motif that will make the H-bonding stronger by increasing the favorable secondary H-bond interactions.
The UPy(RP) array is not soluble in dichloromethane using the NBu4PF6 electrolyte, but it is soluble in acetonitrile. The concentration dependent 1H NMR spectra suggest that UPy(RP) is a monomer in acetonitrile. The cyclic voltammetry scans of the UPy array in CH3CN show three reductions. The first occurs at a potential very similar to that seen with simple model compounds. The second is considerably positive of that observed for the model compounds and the third is very close to the second reduction peak of the model compounds. The first reduction is reversible if the scan direction is switched immediately after the peak, but irreversible if the scan direction is switched after the second reduction peak. As the scan rate increases, the second reduction peak disappears. An oxidation peak at far positive potentials starts to appear only after going through the second and third reduction. DFT calculations suggest the preferred tautomer changes upon reduction, and this may explain the unexpected voltammetry observed in acetonitrile where the compound is not dimerized. To improve the solubility of the UPy array in methylene chloride, TFAB was used as a counterion instead of the PF6. The CV’s of UPy/TFAB array in methylene chloride show similar behavior to that in acetonitrile with an additional fourth reduction wave observed at far negative potential. 1H NMR spectrum of UPy/TFAB at room temperature suggests the presence of two tautomeric forms in methylene chloride. However, at low temperatures, only one tautomer is observed in 1H NMR spectrum that’s believed to be the dimer. Further studies to help elucidate what is actually happening in this system will include taking CV’s at low temperatures in CH2Cl2, and conducting UV-Vis spectroelectroanalytical experiments for the system.
Self-Organized TiO2 Nanotubes: Influence of the Ti Microstructure on the Nanotube Growth
Authors: Sopha Hanna , Macak Jan M. 
Published: February 2020

The synthesis of highly-ordered nanostructures of valve metal oxides has recently attracted huge scientific and technological interest motivated by their possible use in many applications. The most established member of this group of materials is nanoporous Al2O3, which has been prepared two decades ago by anodic oxidation of Al into perfectly ordered, honeycomb-like porous structures employing suitable electrochemical conditions [1]. Owing to the flexibility of the pore diameter/length and the relative ease of the Al2O3 dissolution, its porous membranes have been since than widely used as template material of choice for a range of materials [2-4].
Recently, TiO2 has received the highest attention after Al2O3 motivated by its range of applications, including photocatalysis, water splitting, solar cells and biomedical uses. Very significant research efforts have led to reproducible synthesis of self-organized TiO2 nanotube layers by means of anodic oxidation, during which the starting Ti substrate is converted into a highly-ordered nanotubular layer by anodization in suitable electrolytes [5-7]. Although advancements in the anodic synthesis of self-organized TiO2 nanotube layers have been presented over the past years [8], the degree of ordering has not reached so far the level known from porous alumina [1]. Numerous factors influence the ordering and the homogeneity of the TiO2 nanotube layers.
In the presentation, we demonstrate significant advancements in the understanding of the influence of Ti substrates on the TiO2 nanotube growth compared to the recent state-of-art. Using SEM, AFM, GDOES and optical measurements we will show how to obtain a high degree of ordering, uniformity and homogeneity in the nanotube structure of TiO2 by tailoring the anodization protocol [9, 10]. Furthermore, based on SEM, EBSD and TEM measurements, we will demonstrate how the Ti grain structure influences the lateral uniformity of the nanotube layers [11].
References
1. H. Masuda, K. Fukuda, Science, 268 (1995) 1466.
2. K. Nielsch, F. Müller, A.-P. Li, U. Gösele, Adv. Mater. 12 (2000) 582.
3. H. Asoh et al., J. Electrochem.Soc. 148 (2001) B152.
4. J. Kolar, J. M. Macak, K. Terabe, T. Wagner, J. Mater. Chem. C, 2 (2014) 349.
5. J. M. Macak, H. Tsuchiya, P. Schmuki, Angew. Chem. Int. Ed. 44 (2005) 2100.
6. J.M. Macak et al., Curr. Opin. Solid State Mater. Sci. 1-2 (2007) 3.
7. K. Lee, A. Mazare, P. Schmuki, Chem. Rev. 114 (2014) 9385.
8. J.M. Macak, S. P. Albu, P. Schmuki, Phys. Stat. Sol. (RRL) 1 (2007) 181.
9. H. Sopha, L. Hromadko, K. Nechvilova, J.M. Macak, J. Electroanal. Chem. 759 (2015) 122.
10. H. Sopha, A. Jäger, P. Knotek, K. Tesar, M. Jarosova, J.M. Macak, Electrochim. Acta 190 (2016) 744.
11. J.M. Macak, M. Jarosova, A. Jäger, H. Sopha, M. Klementová, Appl. Surf. Sci., 371 (2016) 607.
Advanced Photoelectrocatalysts for TEMPO-Mediated Alcohol Oxidations
Authors: Chadderdon David J , Wu Ivy , Panthani Matthew G , Li Wenzhen 
Published: February 2020

The transformation of primary alcohols to carbonyls or acids is a fundamental chemical process of interest from both academic and industrial viewpoints, but typically requires stoichiometric oxidants which are costly and generate potentially toxic waste. As an alternative approach, conversion of biomass-derived alcohols in a photoelectrochemical (PEC) cell is a promising environmentally-friendly route, which takes advantage of renewable carbon feedstocks, renewable solar energy, and renewable electricity from wind, geothermal, or photovoltaic sources. In this talk, we will share our recent progress in designing semiconductor / electrocatalyst composite photoanodes made of earth-abundant elements for photoelectrochemical alcohol oxidation.
Previously, we have studied selective electrocatalytic oxidation of biomass-derived alcohols and 5-hydroxymethylfurfural (HMF) on noble metal catalysts.1-2 Electroactive homogeneous catalysts such as (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) represent an alternative to expensive metal catalysts.3 Furthermore, it was recently reported that the electrode potential required to drive TEMPO-mediated alcohol oxidation can be significantly reduced in a PEC reactor, where solar energy is harvested with a bismuth vanadate (BiVO4) semiconductor electrode.4 However, significant electron-hole recombination and efficiency losses due to the competing oxygen evolution reaction (OER) make BiVO4 a poor electrode material for TEMPO oxidation. While it is common to modify semiconductor electrodes with electrocatalysts to enhance OER, such strategies to selectively promote TEMPO oxidation have not been explored.
We present the first composite photoanode for enhanced TEMPO-mediated alcohol oxidation. BiVO4 modified with a cobalt-based electrocatalyst layer facilitated TEMPO oxidation at potentials >400 mV lower than unmodified BiVO4 by enabling facile charge transfer across solid–solid and solid–electrolyte interfaces. The competing OER was completely suppressed, allowing nearly 100% faradaic efficiency for TEMPO oxidation. In this talk, factors that tune the competition between TEMPO oxidation and OER, including photoanode structure, applied potential, and other reaction conditions will be discussed.
References:
(1) Chadderdon, D. J. et al., Green Chem. (2014), 16 3778–3786.
(2) Chadderdon, D. J. et al., ACS Catal. (2015), 5 6926−6936.
(3) Rafiee, M.; Miles, K. C.; Stahl, S. S., JACS (2015), 137 14751−14757.
(4) Cha, H. G.; Choi, K. S., Nature Chem. (2015), 7 328–333.
Metal Alloy ICF Capsules Created By Electrodeposition
Authors: Horwood Corie , Stadermann Michael , Bunn Thomas 
Published: February 2020

Metal capsules for inertial confinement fusion (ICF) experiments are currently produced using micromachining (MM) or physical vapor deposition (PVD). These time and labor intensive methods have failed to yield capsules that meet the exacting standards for smoothness, purity, thickness uniformity and shape required by the National Ignition Facility (NIF). Electrochemical deposition (ED) has the potential of rapidly producing a full density capsule without seams or inclusion of unwanted atomic constituents, the current shortcomings of MM and PVD, respectively. There are, however, specific challenges to ED such as the contact point for applying an electric potential.
We will present our ED approaches to enable high quality metal coatings such as Pt, Au, Ag, Cu and their alloys on spherical mandrels by enabling temporary contact with a working electrode and constant, random motion of the mandrels. Our plating technology has been demonstrated to work well for metal and metal-flashed bead and shell mandrels independent of mandrel density. We will report on ED coating quality metrics including density, surface roughness, and porosity as well as thickness uniformity and sphericity.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Effect of Composition and Temperature on Current Efficiency for Aluminium Electrolysis from Cryolite-Based Molten Alumina Electrolytes
Authors: Morishige Taiki , Haarberg Geir Martin , Gudbrandsen Henrik , Skybakmoen Egil , Solheim Asbjørn 
Published: February 2020

Aluminium smelting from molten cryolite alumina electrolytes is the industrial production process known as the Hall-Héroult process. The current efficiency for aluminium electrolysis in modern cells can be as high as 96 %. The main reason for loss in current efficiency is the socalled back reaction between dissolved aluminium and the anode product of CO2as the following reaction:
Al(diss) + 3/2 CO2 = 1/2 Al2O3+ 3/2 CO
The current efficiency can be improved by suppression of metal dissolution from deposited metal. Decreasing temperature of the cell may also give higher current efficiency. Addition of LiF leads to decreasing the liquidus temperature and also to decrease the metal solubility into the electrolyte. However, low superheat may cause solidification of melt. A laboratory cell to determine the current efficiency was recently modified to obtain more reliable results. The base composition of the electrolyte was Na3AlF6-11.55wt.%AlF3-5wt.%CaF2-4wt.%Al2O3 and electrolysis was conducted at 965 ºC. Electrolysis was performed at constant current density (~0.9 A cm-2) and the current efficiency was determined from the weight of deposited aluminium. The current efficiency at the base condition was 95% in this study. Effects of electrolyte composition by some percent of LiF addition on the current efficiency was studied. The current efficiency and the metal shape on the cathode was changed by the addition of LiF. The loss in current efficiency is strongly related to the content of dissolved aluminium in the electrolyte. Realistic values for the current efficiency were obtained.

References

[1] J. Thonstad, P. Fellner, G.M. Haarberg, J. Híveš, H. Kvande and Å. Sterten. Aluminium electrolysis: Fundamentals of the Hall-Héroult process 3rd edition, Aluminium-Verlag, Düsseldorf (2001). ISBN 3-87017-155-3
[2] P.A. Solli, T. Haarberg, T. Eggen, E. Skybakmoen and Å. Solheim. Light Metals 1994, 195-203 (1994).
[3] X. Wang, R.D. Peterson and N.E. Richards. Light Metals 1991, 323-330 (1991)
[4] E.W. Dewing. Metall. Mater. Trans. B., 22B, 177-182 (1991).
An Electrochemical Procedure to Form Metal Powders from Recycled Hard Particle Embedded Composite Cutting Tools
Authors: Altunbasak Tansu , Kul Mehmet , Karakaya Ishak 
Published: February 2020

Recycling of waste has become an important issue considering the depletion of natural sources and discarded valuable particles and metals. Industrial diamond and other valuable particle embedded into metal matrix cutting tools are manufactured by powder metallurgy techniques [1,2]. They have been widely used in cutting, polishing and grinding of hard metallic and nonmetallic materials like stone, marble and other materials. During its lifetime, a saw blade normally processes around 400 m2of stones [3]. This number corresponds to consumption of only about 60 % of composite cutting tools. Therefore, there are plenty of residual hard particles and combined agents in waste cutting tools [4].
Currently, the general processes of recycling cutting tools involve acid dissolution and separation processes that adopt the principle by utilizing the insoluble characteristics of diamond and tungsten carbide, while dissolving metals. After the filtration of valuable particles, the solution that carries dissolved metal ions are discarded [5,6]. This study offers not only recovering diamond and other valuable particles, but also recycling of metals by co-deposition of metal powders. The waste cutting tools used as anode dissolves in relatively weaker acidic electrolytes and metalic parts are collected as powders at the cathode while hard particles sink to the bottom of electrolyte when power is applied. Temperature, current density, acid concentration and CuSO4concentration of electrolyte are the process parameters to optimize microstructure, density and surface area of metallic powders. It was found that decreasing current density resulted in a more compact and dense powders as it can be seen in Figure below.

References

[1] M. Jeenings, D. Wright, Ind. Dia. Rev. 49 (1989) 70.
[2] M. Meszaros, K. Vadasdi, Process and equipment for electrochemical etching of diamond containing Co–WC tools and recovery of diamond from used steel tools, Int. J. Refrac. Met. Hard Mater. 14 (1996) 229.
[3] A.L.D. Skury, G.S. Bobrovnitchii, S.N. Monteiro, C.C. Gomes, Recovery of synthetic diamonds from scrapped sawblades, Separation and Purification Technology 35 (2004) 185–190
[4] D. Yuan, Method for regenerating diamond with waste material, Chinese Patent Number CN1253116, 2000.
[5] X.D. He, X.Y. Guo, P. Li, K. Huang, and K.H. Xu, Recovery of nickel, cobalt and m anganese from waste acid solution from synthesis of artificial diamond, Hydrometallurgy of China, 2005, 24 (3): 150.
[6] L.H. Guo, and S.T. Cheng, Study on selective leaching and recycling technology of waste diamond tools, Sichuan nonferrous metals, 1996, (1): 19.

Figure 1
Electrolytic Deposition of Doxorubicin-Chitosan Composites on Post Hydroxyapatite Coated Titanium Alloy for Localizing Tumor Treatments
Authors: Yen Shiow Kang , Hsu Shin- Ru , Cheng Yu- Mei , Lai Yu-Liang , Lin Chien- Chung 
Published: February 2020

In order to reduce the side effects caused by the chemotherapy of cancer, various target treatments and drug-delivery systems have been investigated. In this study, the doxorubicin-chitosan composite was deposited on the post hydroxyapatite coated Ti alloy for the tumor treatment by sustaining release of localized drug to achieve the inhibition or apoptosis of cancer cells. In the experiment, cathodic polarization tests coupled with electrochemical reactions were analyzed to speculate the deposition mechanism of doxorubicin, UV-visible spectrometer to measure the doxorubicin loading and release, field emission scanning electron microscope (FESEM) to observe the surface morphology, Fourier transform infrared spectroscopy (FTIR) to characterize the chemical bonds of composite, and X-ray diffractometry (XRD) the crystal structures. The MTT assay was carried out to analyze the toxicity of the drug to cells. It is concluded that doxorubicin-chitosan composites can be successfully deposited on the titanium alloy by the electrochemical method, while the post hydroxyapatite coated specimen with high porosity can enhance the drug loading and reveal the complete drug release. Besides, the electrochemical deposition does not vary any chemical bonding or destroy any medical function of doxorubicin, revealing a practical method for drug loading.
Keywords: Doxorubicin, Chitosan, Hydroxyapatite coated Ti alloy, Localize, Tumor.