bluuebunny/crossref_metadata_2025 huggingface dataset:
Capillarity Based Ion Concentration Polarization for Desalination and Energy Harvesting
Authors: Kim Sung Jae , Park Sungmin , Huh Keon , Jeong Yeonsu , Son Seok Young , Cho Inhee , Lee Hyomin , Kim Ho-Young
Published: February 2020

Ion Concentration Polarization (ICP) phenomenon is a traditional electrochemical ion transportation process near perm-selective membrane and appears as a steep concentration gradient under d.c. bias. The major function of ICP is an active ion control by an external electric field so that it is significantly useful to study the new ion transportation through nanoporous junction (or membrane) and develop novel engineering applications such as biomolecular preconcentrator and electro-desalination. Currently, the inherent capillarity of the nanostructure was demonstrated to initiate the same ICP phenomenon instead of an external power source so that a power-free desalination was achieved. This capillarity ion concentration polarization (CICP) device is shown to be capable of desalting an ambient electrolyte more than 90% without any external electrical power sources (Figure A). Theoretical analysis for both static and transient conditions are conducted to characterize this phenomenon. These results indicate that the CICP system can offer unique and economical approaches for a power-free water purification system in resource limited settings. As a reverse process of CICP, the chemical to electrical energy conversion system was successfully demonstrated as well. Since a convective flow near the perm-selective membrane plays a deterministic role for the ion transportation in both CICP and ICP mechanism, micro-pillar structures that enhance the convective flow around the membrane would accelerate the ion flux leading higher electrical current with the micro-pillar structure (Figure B). These microfluidic visualization platforms are significantly useful in both desalination and energy harvesting applications since it would provide a differential shell of such macroscopic systems that most of important ion exchanges occur microscopically. Figure A. Desalination using CICP mechanism. Figure B. current – time relation in ICP energy harvesting with and without micro pillar structures.

Figure 1
Hydrothermal Synthesis of Fluorescent Carbon Dots By Microwave-Assisted Autoclave Treatment
Authors: Yoshinaga Taishu , Iso Yoshiki , Isobe Tetsuhiko
Published: February 2020

Fluorescent carbon nanoparticles (carbon dots) can be synthesized through hydrothermal treatment of carbon materials in an autoclave. Carbon dots are expected to possess homogeneous properties by using a microwave heating system instead of an electric heating system. Here, we reports particulate and photoluminescent (PL) properties of the carbon dots synthesized by microwave-assisted autoclave treatment.

D(+)-glucose and potassium dihydrogen phosphate were dissolved in ultrapure water. The solution was purged with Ar gas and transferred into a Teflon vessel. The sealed Teflon vessel was heated at 200 °C using a microwave-assisted autoclave. The heating duration was changed from 5 to 60 min. The resulting dispersion was purified by centrifuging, dialyzing, and filtrating to yield a dispersion of carbon dots. The powder of carbon dots was obtained by freeze drying.

According to the TEM observation, the mean particle size of carbon dots increased proportionally to hydrothermal treatment duration. According to the XRD pattern, carbon dots were mainly amorphous. Raman spectra revealed that carbon dots had a framework of graphite. A broad band with its maximum at ~360 nm was observed in PL excitation spectra of dispersions. The PL peak shifted to longer wavelength with increasing excitation wavelength. Thus, the PL spectra contained broad bands with maxima at ~400–700 nm. Maximum PL intensity and absorbance at optimum excitation wavelength increased with increasing hydrothermal treatment duration. This is attributed to an increase in fluorescence-related sites inside grown carbon dots.
Optically and Thermally Stimulated Luminescence in X-Ray Irradiated Sno-Doped Sro-B2O3 and ZnO-P2O3 Glasses for Passive-Type Dosimeter
Authors: Nanto Hidehito , Nakagawa Ryota , Takei Yoshinori , Hirasawa Kazuki , Miyamoto Yuka , Masai Hirokazu , Okada Go , Yanagida Takayuki
Published: February 2020

Optically and thermally stimulated luminescence (OSL and TSL) phenomenon is based on the presence of electron and/or hole traps and luminescence centers in storage phosphor materials. During exposure to ionizing radiation such as x-ray, γ-ray and β-ray, the traps are occupied with charged carriers such as electrons and holes that are created by irradiation with ionizing radiation. De-trapping of these carriers requires energy. The energy is provided by stimulating of the phosphor materials with visible or infrared light (OSL) or by heating of the phosphor (TSL). During a de-trapping transition, free carriers created by the absorption of photons from the stimulating radiation field, recombine with the luminescence centers, whereby visible photons are emitted. Since the OSL or TSL intensity is in the most cases proportional to absorbed dose of ionizing radiation, the phosphor materials which exhibit the OSL and TSL phenomena adapt to two-dimensional imaging sensor for ionizing radiation.

Although imaging plate (IP) using photostimulable phosphor materials such as BaFBr:Eu [1,2] and CsBr:Eu [3] can be now used as two-dimensional sensor for ionizing radiation, these phosphor materials with deliquescent property exhibit poor fading characteristics which is one problem on two dimensional radiation dose estimation using the IP. As a result of surveying many possible phosphor materials, we found that SnO-doped SrO-B2O3 and ZnO-P2O3 glass without deliquescent properties exhibit an efficient OSL and TSL, and good fading characteristics. Typical OSL stimulation and emission spectra of x-ray irradiated SnO-doped SrO-B2O3 glass are shown in Fig.1. In this work, the OSL and TSL characteristics in x-ray irradiated SrO-B2O3 and ZnO-P2O3glasses are in the first time reported and OSL and TSL characteristics are discussed for the passive type dosimeter.

Ref.

[1] K.Takahashi et al., J. Electrochemcal Soc., 32(1985) 1492.

[2] M.Takebe and K.Abe, Nuclear Instruments and Methods, A345(1994) 606.

[3]H.Nanto et al., Nuclear Instruments and Methods, A580 (2007)278.

Figure 1
(Invited) Artificial Intelligence Integrated Multiscale, Multiphysics Computational Chemistry Methods Based on Ultra-Accelerated Quantum Chemical Molecular Dynamics for Luminescence Materials
Authors: Miyamoto Akira , Bonnaud Patrick Alain , Miura Ryuji , Suzuki Ai , Miyamoto Naoto , Hatakeyama Nozomu
Published: February 2020

Our previous research work using different computational methods for the design of phosphor/luminescence materials, show our multiscale, multiphysics computational chemistry methods based on the ultra-accelerated quantum chemical molecular dynamics(UA-QCMD) method which can perform quantum chemical molecular dynamics calculation around 10,000,000 times faster than the conventional first-principles molecular dynamics. In the present study we have demonstrated that the UA-QCMD has high accuracy in comparison with density functional theory(DFT) method and thermodynamic data for a variety of compounds including metal, metal oxides, nitrides, and sulfides which are important as luminescence materials and devices. A variety of applications of the artificial intelligence integrated multiscale, multiphysics computational chemistry methods based on the UA-QCMD are also presented in the meeting.

References:

1.
H. Onuma et al., J. Ceramic Process. Res. 14(2013) 48.

2.
H. Onuma et al., J. Soc. Inform. Display, 18(2010) 211.

3. M.K. Alam et al., J. Phys. Chem. C., 113(2009) 7723.

4. F. Ahmed et al., J. Phys. Chem. C., 113 (2009) 15676.
Synthesis and Luminescence Properties of Eu3+-Activated La5BSi2O13 Phosphor for W-LED Applications
Authors: Chen Chun-Ting , Liu Wei-Ren
Published: February 2020

The Eu3+-activated La5BSi2O13 was successfully synthesized via a solid state reaction. The phase purity, crystal structure, photoluminescence properties, thermal stability and chromaticity coordinate have been firstly investigated. A typical Eu3+ emission and excitation spectra were observed. The excitation spectrum was comprised of sharp peaks at 300 nm – 500 nm which can be ascribed to the forbidden 4f-4f transitions of Eu3+. The emission spectrum was dominated by a large peak located at 615 nm which corresponds to the 5D0 → 7F2 transitions of Eu3+. The results indicate that La5BSi2O13:Eu3+ is a potential candidate as red component for white light-emitting diode applications.
A New Green Phosphor Using Solid-Solution and Their Structural and Optical Properties
Authors: Kim Yoon Hwa , Im Won Bin
Published: February 2020

Garnet structure (cubic, space group Ia-3d) is recognized as highly stable and efficient host for white solid state lighting application. However, yellow Y3Al5O12:Ce3+ phosphor is associated with patent infringement while a replacement of yttrium with lutetium of form a similar structure Lu3Al5O12:Ce3+ (LuAG:Ce3+) phosphor would raise the cost of the LED device.

The solid-solution design is an efficient route to develop new phosphors with various compositions. The commonly used solid-solution design method concentrates on the cation/anion substitution. The benefits vary from the color tuning of the peaking emission, to improved structural rigidity or chemical stability.(1) Garnet structure which accommodates wide variety of cations can be chosen as a template for such solid solutions.

In this study, we report a new green-emitting phosphor, the Ce3+-doped garnet, which has better luminescence properties than the commercial LuAG:Ce3+phosphors. The influence of expanding substituted site by solid-solution and the change of photoluminescence intensity have been explored, and established their correlation. By the fabrication of white laser diodes, we explored its potential suitability in white laser diodes applications. This suggests that the phosphor displays great potential for application in white light generation using blue laser diodes.

1. W. B. Im, N. George, J. Kurzman, S. Brinkley, A. Mikhailovsky, J. Hu, B. F. Chmelka, S. P. DenBaars and R. Seshadri, Advanced Materials, 23, 2300 (2011).

Figure 1. Photoluminescence excitation spectra and emission spectra of optimized sample by solid-solution and commercial LuAG:Ce3+phosphor at room temperature.

Figure 1
Discovery of Novel Narrow-Band Red Phosphors Using High-Throughput First Principles Descriptors
Authors: Wang Zhenbin , Chu Iek-Heng , Zhou Fei , Ong Shyue Ping
Published: February 2020

As a red component, nitride phosphors are widely used in achieving warm-light-emitting diodes (LEDs) with high color rendition. There is therefore a huge impetus for the development of new nitride phosphors to further improve the luminous efficacy and color rendition of phosphor-converted LEDs. However, the harsh synthesis conditions (high temperature and/or high pressure) of nitride phosphors have severely hindered this development. In this talk, we outline a computationally efficient multi-property screening framework for identifying promising narrow-band red-emitting phosphors utilizing the Eu2+ activator based on first principles calculations. This screening relies on the use of first principles descriptors that correlate with desired red phosphor properties, such as high thermal/chemical stability, high quantum efficiency, near-UV absorption wavelength and narrow red emission band. We will demonstrate the applicability of our approach through its ability to identify existing well-known narrow-band red phosphors. Finally, we will propose several promising novel red phosphor host materials using this approach. Our study presents a highly efficient way to discover and design novel phosphors for illumination-grade lighting.
(Keynote) Towards Implantable Miniature Glucose-O2 Biofuel Cells
Authors: Mano Nicolas
Published: February 2020

Miniature glucose/O2 biofuel cells are of particular interest because they may power implanted medical devices. However, numerous challenges remain to overcome before envisioning such applications.

 Other than well-established experiments in aqueous buffer, little work has been performed in whole human blood because it contains numerous inhibiting molecules. In my talk, I will show the results obtained with 30 biofuel cells operating in anonymized, random and disease-free whole human blood samples. By designing our anodic and cathodic bioelectrocatalysts with osmium based redox polymers and home-made enzymes we could reach a high selectivity and biofunctionnality. After optimization, BFCs generate power densities directly proportional to the glycaemia of human blood and reached a maximum power density of 129 µW.cm-2 at 0.38 V vs. Ag/AgCl at 8.22 mM glucose. I will also discuss our recent achievement towards implantation in mices and toxicity issues, which are generally raised with the use of Osmium complexes.
(Invited) Nanopore Sensing with a Stable Lipid Bilayer in Microfabricated Devices
Authors: Kawano Ryuji
Published: February 2020

Artificial cell membranes have emerged as a biomimetic tool in such areas as membrane protein study, synthetic biology, and drug discovery. Planar lipid bilayer is the planar membrane and it is used for measuring transmembrane current of ion channels, membrane peptides, or pore-forming proteins. However, the stability of the lipid bilayer and the reproducibility of bilayer formation are serious issues for the practical experiments. To improve these issues, we have tried to use microfabrication technologies based on photolithography, micro-milling, and 3D printing.

Microfabrication and microfluidics have the potential to significantly change the way of recent chemical or biological experiments. Microfabricated devices offer the ability to work with smaller sample volumes, shorter reaction time, and the possibility of parallel operation. They also hold the promise of integrating an entire onto a single chip, as lab-on-a-chip. In this presentation, I introduce a stable and reproducible preparation procedure for the planar lipid bilayers using “droplet contact method” in microfabicated devices. In addition, I will show the recent applications, such as single molecule detection with biological nanopores and DNA computing in the droplet network.
An Electrochemical Scaffold for Wound-Related biofilms Elimination
Authors: Sultana Sujala T. , Atci Erhan , Babauta Jerome T. , Falghoush Azeza Mohamed , Snekvik Kevin , Call Douglas R , Beyenal Haluk
Published: February 2020

Biofilms are commonly found on infected wounds that cause delay in wound healing. Conventional approaches such as antibiotics or topical antimicrobial agents remove bacteria and biofilms only partially due to depletion of antimicrobial concentration. Therefore, in this work we propose to develop a novel electrochemical scaffold (e-scaffold) capable of continuous controlled delivery of sufficient concentration of H2O2 at a constant potential that can destroy biofilms without damaging host tissue. When constant electrical potential at –600 mVAg/AgCl was applied to an e-scaffold made of conductive carbon fabric, dissolved oxygen was reduced to generate a ~25 μM of H2O2 near the fabric surface as detected by microelectrode measurement. When overlaid onto existing biofilms, e-scaffold reduced the number of biofilm cells by log (3.95 ± 0.28) (n=3, P<0.001) within 24 h. When e-scaffold was applied against biofilm infected porcine dermal explants, the number of viable cells was reduced by log (2.98 ± 0.10) (n=3, P<0.001) and no histological damage to the underlying mammalian tissue was observed. This research establishes a foundation for an alternative antibiotic-free strategy to eliminate wound-related biofilms.
Study of Microbial Fuel Cell for Implantable Application
Authors: Narla Aashray , Upadhyaya Dhruv , Amaravati Sivakumar , Chittur Krishnaswamy Subramaniam
Published: February 2020

Microbial fuel cells (MFCs) are a hybrid bioelectrochemical system, which converts biosubstrates directly into electricity by effectively oxidizing those using bacteria under ambient temperature/pressure condition. The potential, developed between the bacterial metabolic activity and electron acceptor, was separated by a membrane (Perfluro sulphonic acid membrane in this case) manifesting bioelectricity generation. The achievable power output from MFCs can be tuned by modifying the system design, such as optimization of the Membrane Electrode Assembly (MEA) structure, cell operating conditions, and the choice of biocatalyst. MFC’s are good candidates for implantable applications. The advantages for implantable application are biocompatibility and natural, safe and light, amenability to sterilization, continuous power output, minimal invasiveness, long life cycle, easy to integrate electronics.

Selection of the anode-cathode electrodes materials and structure is one of the critical challenges of MFC and more so for the implantable application. These can affect the power density and Coulombic efficiency. The electrochemical characteristics of MFC are studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and polarization profiles. Carbon and blends with graphene are used for developing the electrode diffusion structure. The anode is filled with bacteria which is E.Coli where luria bertani medium is used to grow the bacteria. The cathode is coated with manganese dioxide. The achievable cell potential is around 0.7-0.8V. For implantable application a power density of, in vitro > 10 μW / cm² and in vivo > 5 μW / cm² is targeted. Complete characterisation and optimisation parameters of the cell will be presented.
Direct Electron Transfer of Hemoglobin on Indium-Tin Oxide Electrodes Synthesized By Dip-Coating Methods Under Different Sintering Temperature
Authors: Ayato Yusuke , Mochizuki Dai , Sugimoto Wataru
Published: February 2020

The direct electron transfer (DET) between electrodes and redox proteins is important when considering practical applications such as body implantable devices for cardiac resynchronization therapy (CRT) and deep brain stimulation (DBS), since such electrical devices should require biocompatibility, simplicity of electrodes, potential difference in electrochemical cells, etc. We have investigated the DET properties of hemoglobin (Hb) molecules on indium-tin-oxide (ITO) electrodes [1-3]. In our previous study, the ITO electrodes were synthesized on glass plates by using dip-coating solution with different Sn/(Sn+In) molar ratio, and Hb molecules showed the DET activity on the synthesized ITO electrodes [3]. It was found that the DET activities of Hb molecules were different at ITO electrodes synthesized from different Sn ratio. The largest DET current was observed on the ITO electrode synthesized from a Sn ratio of 0.50. The results also suggested from previous studies with different Sn ratio that the active sites and electrical properties of ITO might be related with the DET behavior with Hb molecules.

To understand the relationship between crystallinity of ITO and DET of Hb molecules on electrode surfaces, in this study, ITO electrodes were prepared on quartz plates under different sintering temperature from 350°C to 950°C for 15 min by using dip-coating solution with the Sn ratio of 0.50. The coating procedure was repeated ten times. X-ray diffraction (XRD) peaks attributed to Sn-doped In2O3 were observed, with the peak intensity increasing with increasing sintering temperature.

Cyclic voltammetry (CV) was conducted with a three-electrode system in 39 mM phosphate buffered saline (PBS; pH 7.4) with or without 100 μM Hb solution. ITO sintered at 350°C and 950°C behaved as poor electrodes due to their high electrical resistance. Hb molecules showed good DET activities on the ITO electrodes sintered at 500°C, 650°C, and 800°C. The results indicated that there were optimum crystallinity of the ITO electrodes for showing DET activity to Hb molecules.

References

[1] Y. Ayato, K. Sakurai, S. Fukunaga, T. Suganuma, K. Yamagiwa, H. Shiroishi, J. Kuwano, Biosens Bioelectron, 55 (2014) 14.

[2] Y. Ayato, N. Matsuda, Energies, 7(1) (2014) 1.

[3] Y. Ayato, W. Sugimoto, ECS Trans., 66(39) (2015) 29.
High Power Glucose/O2 Biofuel Cell Constructed from MgO-Temlated Carbon Modified Carbon Cloth
Authors: Niiyama Ayumu , Tsujimura Seiya
Published: February 2020

Enzymatic biofuel cells (EBFCs) based on enzyme electrocatalysts are devices to directly convert chemical energy of glucose and alcohol to electronical energy. EBFCs gather attention as a power source of wearable electronic sensor devices because they have high biocompatibility. In this paper, we report a glucose/O2 EBFC using flexible carbon cloth electrodes modified with mesoporous carbon particle, which shows high power density as high as 2 mW cm-2. Moreover, the capacity of the BFCs can be controlled by the mole number of glucose added.

Porous carbon electrode was fabricated by modifying the MgO-templated mesoporous carbon (MgOC) on carbon cloth in order to enlarge surface area and to immobilize enzyme and redox mediator on electrode surface. MgOC is a kind of pore size-controlled porous carbon; mesopore size can be controlled by alternating the MgO template size. For the anode catalyst, flavin adenine dinucleotide dependent glucose dehydrogenase (FAD-GDH) from Aspergillus terreus was used. Naphthoquinones (NQ) were used as anode mediator. FAD-GDH and NQ were modified on the anode 0.19 and 1.5 mg cm-2, respectively. For the oxygen-reducing cathode, bilirubin oxidase (BOD) was used as enzyme, and 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid ammonium salt) (ABTS) as mediator. BOD and ABTS were modified on the cathode 1.25 and 1.25 mg cm-2, respectively. 1.0 M phosphate buffer (pH = 7.0) was used as an electrolyte. A cellophane sheet was sandwiched between the anode and cathode as a separator.

Figure 1 shows the cell power (solid lines) and cell voltage (broken lines) as a function of current density of the EBFCs. The maximum output power density of BFCs using 1,2-NQ and 1,4-NQ for anode mediators were 1.69 and 2.06 mW cm-2, receptively, because the redox potential of 1,4-NQ is more negative than that of 1,2-NQ. Figure 2 shows the cell capacity of the BFCs as a function of glucose concentration added to the cell. The capacity of the cell increased linear with an increase of the mole number of glucose.

Figure 1
(Invited) Electrochemical Luminescent Imaging of Activated Neutrophils Using Multi-Microwell Array Electrode
Authors: Tamiya Eiichi
Published: February 2020

Vasculitis is an autoimmune disease leads to various sicknesses (e.g. arteriosclerosis). Mechanisms of vasculitis have not been accurately understood, and early detection and diagnosis of vasculitis remain constant challenges. One of the causes of vasculitis is neutrophil-derived reactive oxygen species (ROS) that attack blood vessels. Therefore, detection of ROS derived from activated neutrophils could be important for early diagnosis of vasculitis. Herein, we developed a device for detection of ROS from activated neutrophil at single-cell resolution using electrochemiluminescence (ECL) method. ECL is it’s a highly sensitive method, which is suitable for detection of ROS from a single activated neutrophil. Results & discussion We constructed a multi-microwell array electrode device that enables to detect the generation of ROS from activated neutrophils. Microwell array was fabricated using PDMS and put on an electrode. By sealing neutrophils into the microwells, we could prevent diffusion of ROS, and keep its concentration high. Luminescence was generated by the reaction between luminol and ROS, and its intensity was quantified using EM-CCD camera. Neutrophils were isolated from healthy human blood, and were activated by adding PMA. The activated neutrophils are recognized as a model cells for vasculitis researches. The activated cells and non-activated cells were trapped in microwells and their luminescence was quantified by the EM-CCD camera. As a result, we succeeded in detecting ROS from activated neutrophils. This device may have potential to diagnose vasculitis by comparing the number and condition of activated neutrophils between healthy people and vasculitis patients.
Electrochemical Reduction of Alkenes Mediated By Vitamin B12 Model Complex
Authors: Shimakoshi Hisashi , Zhongli Luo , Hisaeda Yoshio
Published: February 2020

Naturally-occurring B12(cobalamin)-dependent enzymes catalyze various molecular transformations that are of particular interest from the viewpoint of biological chemistry as well as synthetic organic chemistry and catalytic chemistry. The CoI species of B12 derivative is widely known as a supernucleophile that forms an alkylated complex by reaction with an alkyl halide.1 The alkylated complex is a useful reagent for forming radical species as the cobalt-carbon bond is readily cleaved homolytically by photolysis. Recently, application of CoI complex for proton reduction was extensively studied and electrochemical hydrogen evolutions by cobalt complex have been reported.2 In these studies, Co-H complex is thought to be an intermediate for hydrogen evolution. These results prompted us to investigate application of cobalamin derivative for new bio-isnpired reaction.3 The electrochemically generated CoI species of B12 derivative may reacts with proton (CF3COOH, CH3COOH etc..) to form Co-H complex, and can utilize for alkene reduction (Figure 1). Scope of substrate, detailed reaction mechanism, comparison to catalysis of other cobalt complex will be reported.

References

(1) a) M. Giedyk, H. Shimakoshi, K. Goliszewska, D. Gryko, Y. Hisaeda, Dalton Trans., 2016, in press (Inside cover); b) H. Shimakoshi, Z. Luo, T. Inaba, Y. Hisaeda, Dalton Trans., 2016, in press (Back cover).

(2) a) V. Artero, M. Chavarot-Kerlidou, and M. Fontecave, Angew. Chem. Int. Ed., 50, 7238 (2011), b) W. T. Eckenhoff, R. Eisenberg, Dalton Trans, 41, 13004 (2011).

(3) H. Shimakoshi and Y. Hisaeda, ChemPlusChem, 79, 1250 (2014) (Back cover).

Figure 1
Competition Studies and the Use of Mechanistic Insight to Overcome Synthetic Barriers
Authors: Moeller Kevin D , Perkins Robert J , Gonzalez Luisalberto , Feng Ruozhu
Published: February 2020

Because intramolecular anodic olefin coupling reactions involve a reversal in polarity of a normally nucleophilic olefin, they can be used to develop entirely new pathways to a variety of molecules. The reactions are compatible with a wide variety of functional groups, the generation of fused, bridged, and spirocyclic ring skeletons, and the formation of quaternary carbons. However, not all anodic olefin coupling reactions work. The reactions are triggered by the formation of a highly reactive radical cation intermediate. If the desired reaction pathway is not fast enough, then the radical cation will initiate undesirable reaction pathways, often involving elimination, fragmentation, or solvent trapping. When this occurs, the question quickly becomes what can be done to solve the problem and channel the reaction down a more productive pathway?

     The best way to address this question has been to carefully probe the mechanism of the reactions, identify the nature of the undesirable reactions, and then manipulate the relative rates of the reactions available to the radical cation to favor the process that is wanted. Several steps in the reaction can be important, but two play an especially important role (Scheme 1). First, the rate of the cyclization is important. If the cyclization is too slow, then side reactions involving the reactive radical cation will begin to dominate. The rate of the second oxidation (k2) is also critical for the success of the reaction. Many radical cyclizations are reversible and in those cases the loss of the second electron helps to drive the product to completion.

     Understanding these principles is essential for the design of more complex reactions, and in the talk to be presented, a series of new anodic cyclization reactions (Scheme 2) will be used to highlight the important interplay between mechanistic considerations and synthetic design. Each of the reactions discussed will involve a transformation that was originally a failure but is now a cornerstone of ongoing synthetic efforts.

Figure 1
Dissymmetric Bis(dipyrrinato)Zinc(II) Complexes: Rich Variety and Bright Red to Near-Infrared Luminescence with a Large Pseudo-Stokes Shift
Authors: Sakamoto Ryota , Nishihara Hiroshi
Published: February 2020

Bis(dipyrrinato)metal(II) and tris(dipyrrinato) metal(III) complexes have been regarded as much less useful luminophores than their boron difluoride counterparts (4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes, BODIPYs), especially in polar solvent. We proposed previously that dissymmetry in such metal complexes (i.e., two different dipyrrinato ligands in one molecule) improves their fluorescence quantum efficiencies. In this work, we demonstrate the universality and utility of our methodology by synthesizing eight new dissymmetric bis(dipyrrinato)zinc(II) complexes and comparing them with corresponding symmetric complexes. Single-crystal X-ray diffraction analysis, 1H and 13C NMR spectroscopy, and high-resolution mass spectrometry confirm the retention of dissymmetry in both solution and solid states. The dissymmetric complexes all show greater photoluminescence (PL) quantum yields (ΦPL) than the corresponding symmetric complexes, allowing red to near-infrared emissions with large pseudo-Stokes shifts. The best performance achieves a maximum PL wavelength of 671 nm, a pseudo-Stokes shift of 5400 cm−1, and ΦPL of 0.62−0.72 in toluene (dielectric constant εs
= 2.4), dichloromethane (εs
= 9.1), acetone (εs
= 21.4), and ethanol (εs
= 24.3). The large pseudo-Stokes shift is distinctive considering BODIPYs with small Stokes shifts (∼500 cm−1), and the ΦPL values are higher than or comparable to those of BODIPYs fluorescing at similar wavelengths. Electrochemistry and density functional theory calculations illustrate that frontier orbital ordering in the dissymmetric complexes meets the condition for efficient PL proposed in our theory.
Redox-Responsive Dimerization in a Ferrocene-Containing Ureidopyrimidone Supramolecular Assembly
Authors: Smith Diane K. , Cedano Mario
Published: February 2020

An important goal in supramolecular chemistry is the development of stimuli-responsive systems, where the strength of the intermolecular interactions can be altered by external signals such as changes in light, temperature, pH or voltage of an electrode. Applications include self-healing supramolecular polymers and gels, controlled release of entrapped molecules, and smart materials. In this paper, the results of our recent electrochemical studies with a ferrocene-containing ureidopyrimidone (UPy) will be described. The UPy system, introduced by Meijer, can form two self-complementary 4 H-bond arrays (AADD or ADAD) which dimerize in relatively non-polar solvents such as methylene chloride. Due to their ease of synthesis and relatively strong H-bonding they have been heavily investigated in a variety of functional supramolecular assemblies and polymers. By introducing an electroactive ferrocene it may be possible to control the strength of interaction to create a redox-responsive UPy. There are two different places an electroactive group can be attached to the UPy: on the urea side (R1 position ) and on the pyrimidinone side (R2 position). Following earlier studies by Alexander et al. (Chem Comm 2007, 22, 2246) we have prepared a UPy with a ferrocene in the R2 position. Concentration-dependent CV studies indicate a square scheme type mechanism. In the starting ferrocene state, the AADD dimer is preferred. Oxidation to the ferrocenium results in conversion to another form with a less positive E1/2. Preference for this new form increases at lower concentrations suggesting that it is a monomeric species, which would indicate that oxidation breaks apart the dimer as desired. Alternatively it is possible that the observed concentration dependence results from rate-limiting dissociation of the dimer, but the monomer then tautomerizes to the ADAD form which re-dimerizes. More detailed investigations are currently underway to try and distinguish between these possibilities.
Structure-Activity Relationship of AMP-Luciferin Analogs for In Vivo Imaging
Authors: Kitada Nobuo , Iwano Satoshi , Kiyama Masahiro , Saito Ryohei , Hirano Takashi , Niwa Haruki , Maki Shojiro
Published: February 2020

Firefly bioluminescent system is attracting widespread attention as an in vivo imaging tool. Recently, Near-InfraRed (NIR) light (650~1000 nm) is hot topic due to high living body permeability. Although many NIR fluorescence imaging tools are commercialy available, these are not self-luminescent.

We study the relationship between structure modification and the firefly luminescence wavelength, that the luciferase of Photinus pyralis (Ppy) was used. And we have succeeded in development of Akalumine® which is a world's first near-infrared light in vivo imaging tool of bioluminescence. Akalumine® is employ in vivo imaging for mice. However, we wish Akalumine® is used much bigger animals like a marmoset, miniature pigs for in vivo imaging. Although Akalumine® is useful for in vivo imaging, it is not enough for big animal. We will give a suggestion for solving this problem.

Luminescence of a firefly is two stepwise reactions. Luciferase convert luciferin into AMP-luciferin (intermediate) by adenylation reaction, andthen AMP-luciferin is converted into oxyluciferin by oxygenation reaction. It is known that emission efficiency increase 1000 fold by using the AMP-luciferin, instead of lucifein. So the emission efficiency of luciferin can be raised when AMP-luciferin is used. However, it is very unstable. Then, I will make elaborate AMP-luciferin analogs, and I try to clear practical problem by establishing structure-activity relationship of AMP-luciferin analogs.

I will present the details of this result.

Figure 1
Quartz Crystal Microbalance Electrode Modified with Thermoresponsive Crosslinked and Non-Crosslinked N- Isopropylacrylamide Polymers. Response to Changes in Temperature
Authors: Karbarz Marcin , Marcisz Kamil , Stojek Zbigniew Jan
Published: February 2020

Electrochemical quartz crystal microbalance (EQCM) electrode was modified with environmentally sensitive polymers. The polymer layers on the electrode were composed of either crosslinked or non-crosslinked thermoresponsive poly(N-isopropylacrylamide). For anchoring thin gel films on the electrode surface the electrochemically induced free-radical polymerization (EIFRP) was employed. The electroreduction of the peroxydisulfate anion led to generation of free radical. This radical initiated the free radical polymerization process that led to the formation of a thin gel layer attached to the electrode surface. To monitor in situ the growth of the polymer film the changes in resonant frequency of the quartz-crystal were recorded. A significant decrease in the frequency (growth of the layer) was seen in the potential range where the reduction of peroxydisulfate anion took place. The morphology of the layers was examined with a scanning electron microscopy (SEM). The phenomenon of volume phase transition (shrinking/swelling process) in the gel layers initiated by a change in temperature was investigated. Unexpected big, sharp and of negative sign minima appeared at the change-in-frequency vs. temperature plots. These minima were not seen in the plots obtained for the polymers without linker. That situation should be useful in the investigation of chemical interactions proceeding under the conditions of volume phase transition. The influence of volume phase transition on the transport of a member of a model red-ox system, ferro- and ferricyanide couple, and therefore on height of its voltammetric response was examined. The changes in electrochemical properties of the layers induced by volume phase transition were monitored with electrochemical impedance spectroscopy.
Pd/Uio-66/Ti Electrode for Electrocatalytic Debromination of Tetrabromobisphenol a
Authors: Jiang Fang , Feng Xiangwen , Chen Huan
Published: February 2020

Metal organic frameworks (MOFs) have engendered great interest due to their high surface areas, tunable porous size, and functionalities. They are explored in a wide range of applications including absorption, gas storage or separation, catalysis, biomedicine and drug delivery. Presently, a large number of reports appraise the application of MOFs in the field of electrochemistry, from rechargeable batteries, supercapacitors to fuel cells. Among these various metal organic frameworks, UiO-66 as a type of highly stable zirconium-based MOF linking by 1,4-benzenedicarboxylate (BDC), has been extensively studied. It is reported that UiO-66 demonstrates high structural stability in water medium, thus, it shall be a feasible strategy to incorporate UiO-66 with other functional materials for the applications in aqueous medium, water treatment and water splitting for instance. Herein, palladium nanoparticles supported UiO-66 was fabricated on Ti plate electrode (Pd/UiO-66/Ti) in this study. White UiO-66, as a bridging layer with controlled size and thickness, was first deposited on Ti plate via an electrochemical film deposition method. UiO-66/Ti plates of different thickness were acquired by changing the ratio of electrochemical deposition solution. Pd/UiO-66/Ti was further made by dipping Pd2+ solution onto the UiO-66 surface and then reduced by impregnating in 0.1 % NaBH4 solution for two hours. The obtained dark Pd/UiO-66/Ti electrode was characterized by X-ray diffraction (XRD). And the electrochemical properties of the Pd/UiO-66/Ti cathode electrode were investigated through cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The results revealed that UiO-66 films with different thickness were successfully deposited on the Ti cathodes (UiO-66/Ti), Pd particles well dispersing on the surface of the UiO-66/Ti. The electro-catalytic performance was evaluated by electrocatalytic debromination of 5 mg/L tetrabromobisphenol A (TBBPA) in a 200 mL vessel, containing Pd/UiO-66/Ti as cathode, graphite as anode at a current of 6.67 mA/cm2. It was found that degradation rate of TBBPA was 80% within 60 min by Pd/ UiO-66/Ti cathode electrode. The excellent electro-catalytic performance could be ascribed to the adsorption of TBBPA on UiO-66 and the reaction with hydrogen at the palladium/UiO-66 interface. The results indicated that Pd/UiO-66/Ti should be a promising cathode for the application on electrochemical.
Growth of Transition Metal Nanoclusters to Get Enhanced Catalytic Abilities
Authors: Hussain Tajamal , Ashraf Munazza , Mujahid Adnan , Raza Muhammad Hamid , Shehzad Khurram
Published: February 2020

Electro deposition is one of the economical and straight forward method to get metal in desired structure and size. In many cases, electro deposition is used in different fashions to have nanostructure. Here, electro deposition was carried out in citrate bath as well as reverse microemulsion. Citrate bath was prepared for different transition metals and these metals were deposited on copper substrate. Metal nanoparticles got deposited by reverse microemulsion method using Triton X-100 as a surfactant. Stable and transparent microemulsion was synthesized at room temperature. After the formation of metal ions in the emulsion, they were reduced at the copper electrode and deposition took place. Reverse micelles provided suitable environment to the metal ions and acted as a template. The electrochemical activity of the electrodes prepared by both methods was compared by carrying out oxidation of alkaline solution and alcohols. It was observed that electrodes modified using reverse micro emulsion as template showed considerable enhanced catalytic abilities than electrodes prepared in citrate bath. Study of surface morphology through scanning electron microscopy indicates the formation of nanoclusters of deposited metals in case of reverse microemulsion. These nanoclusters, nanocatalysts, are mainly responsible for enhanced catalytic abilities.
Electrochemical Synthesis of Single Pt Atom Catalyst for Hydrogen Reactions
Authors: Chen Wei-Fu , Fang Si-Lin , Chen Li-Chyong , Sasaki Kotaro
Published: February 2020

Single metal atom/center catalysts that bridge heterogeneous and homogeneous catalysis have very recently attracted much attention for the maximum usage of noble metal atom and great potential to achieve high activity and selectivity [1]. Very recently, several techniques have been developed to achieve supported single platinum atom for catalysis on metal oxides including Al2O3 and iron oxides which have a strong interaction with platinum atoms [2,3]. One key issue is that the high surface free energy of metal atom usually induces aggregation of metal atoms into big clusters. These techniques, however, only allow metal atoms prepared on oxide materials. In this study, we investigated the possibility of preparing Pt atoms by using electrochemical deposition techniques and whether the Pt atoms can be deposited on non-oxide materials. The result to the question turned out to be in the affirmative, yielding Pt atoms on carbon materials in addition to metal oxides.

According to the two-electron-reaction models, cathodic hydrogen evolution in acidic aqueous media on bulk Pt proceeds through a two-steps Volmer–Tafel mechanism. First, the discharge step (Volmer reaction); second, the recombination step (Tafel reaction). While on single Pt atoms, we demonstrated that the HER occurs through a Volmer–Heyrovský mechanism, that is, the rate-determining step is the electrochemical desorption of Hads and H3O+ to form hydrogen (Figure 1). The electrocatalytic activities and mechanism of the hydrogen evolution reaction (HER) and hydrogen oxidation reactions (HOR) will be reported.

References

1. Yang, X. F. et al. Accounts Chem. Research
2013, 46, 1740.

2. M. Moses-DeBusk et al. J. Am. Chem. Soc.
2013, 135, 12634.

3. Qiao et al. Nature Chem.
2011, 3, 634-641

Figure 1
(Invited) Ionic Liquid Enables Technologies for Winning Rare Earth Elements
Authors: Mudring Anja-Verena
Published: February 2020

Rare earth elements are amongst the most critical materials, they are crucial for a number of energy related technologies relying on the superior catalytic, optical or magnetic properties that can be achieved in their compounds.

As catalysts they find application in fluidic catalytic cracking (FCC) catalysis, one of the most important processes in petrochemistry where they are used to convert the high-molecular weight hydrocarbon fraction of crude oil into more useful lower-weight hydrocarbons. Rare earth based phosphors are the key part for energy conversion in compact fluorescent lamps (CFLs) and light emitting diodes (LEDs) which are currently the most important energy efficient lighting devices. As phosphors rare earth based materials find also application in scintillators for radiation detection (as used by Homeland Security) or for medical imaging. As security makers they can be found in passports and banknotes. Currently an increased consumer demand for rare earth materials arises from the increased use of cell phones and tablets. The exceptional properties of rare earth elements are particularly used in alloys for permanent magnets. The properties of SmCo5 and Nd2Fe14B are unsuperseded. Because of their high field strength Nd2Fe14B magnets are used in hard drives, motors for hybrid cars or wind turbines. SmCo5 is less used as it not only has a weaker field strength, but is also more expensive because it contains two critical elements, samarium and cobalt. However, as the Curie temperature of SmCo5 is higher than that of Nd2Fe14B is used in applications where high field strengths at high temperatures are needed.

However, the stable economic supply of rare earth elements is not guaranteed and, thus, the pproduction and use of rare earth compounds constitute an important strategic and dynamic segment of the electronic, chemical and energy industries. The presentation will discuss the importance and criticality of rare earth elements and will give insights into how ionic liquids can provide technology solutions for rare earth recycling, separation and production, most importantly, the electrodeposition from ionic liquids as an alternate, greener process to the currently used high temperature process.
Influence of the Alkaline Earth Metal Cations on the Standard Rate Constants of Charge Transfer for the Redox Couple Ti(IV)/Ti(III) in Chloride-Fluoride Melts
Authors: Vetrova Daria A. , Kuznetsov Sergey A.
Published: February 2020

The aim of the present investigation was study of charge transfer kinetics for the redox couple Ti(IV)/Ti(III) in the (NaCl-KCl)equimol.-NaF(10 wt.%)-K2TiF6 melt and the estimation of the alkali earth metal cations influence on the standard rate constants of charge transfer (ks
) for this redox couple.

Method of cyclic voltammetry was employed for the determination of the standard rate constants of charge transfer. The electrochemical redox process:

Ti(IV) + e-↔ Ti(III) (1)

was classified as quasi-reversible in the range of scan rate 0.75 V s-1≤ν≤2.0 V s-1. The standard rate constants of charge transfer for the reaction (1) were calculated based on the Nicholson’s equation.

It was shown, that k
s increase with increasing temperature and the temperature dependence of k
swas described by the following empirical equation:

log k
s=(1.505±0,32)–(3364±675)/Т (2)

The activation energy of charge transfer calculated from (2) was found equal to (64.41±13) kJ mol-1.

Influence of strongly polarizing cations of Mg2+, Ca2+, Sr2+ and Ba2+on the standard rate constants of charge transfer for the redox couple Ti(IV)/Ti(III) was studied.

It was determined that addition of alkali earth metal cations resulted in increasing of ks
up to the certain mole ratio of Me2+/Ti(IV), which was inversely proportional to ionic potential of cations. Further addition brought some decreasing of the standard rate constants. Increase of ks
is connected with substitution of Na+ and K+ cations by strongly polarizing cations in the second coordination sphere of titanium complexes that led to increasing of the bond distance between Ti and F- ligands and decreasing of titanium fluoride complexes strength. Decrease of ks
at the definite ratio of components can be explained by increasing of the viscosity melts, which brings to decreasing of the diffusion coefficients.

It was established the linear dependence of ks
on ionic potential of alkali earth metal cations and the maximum value was obtained for complexes with outer sphere cations of magnesium. The temperature dependences for the maximum values of ks
in the melts containing strongly polarizing cations were fitted by empirical equations and the activation energies of charge transfer were calculated. Values of activation energy for systems with strongly polarizing cations are considerably less than activation energy for initial system.

Acknowledgments

The work was financially supported by Russian Foundation for Basic Research (15-03-02290_a).