bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Anisotropic Magnetism of an Endohedral Metallofullerene for Molecular Location Sensor
Authors: Takano Yuta , Tashita Ryo , Suzuki Mitsuaki , Imahori Hiroshi , Nagase Shigeru , Akasaka Takeshi 
Published: February 2020

Location recognition in molecular-scale provides valuable information on positional relationship, absolute conformation and dynamics of molecules. They can be used for deep understanding of nature of functional molecular materials or for elucidating biological processes. Therefore, a number of molecular probes have been developed and reported to date for molecular recognition and location determination.
Recently, our group has reported anisotropic magnetism of an endohedral metallofullerene (EMF) Ce@C82 both in a pristine form and chemically functionalized form.1,2 Remarkably, the anisotropy of the magnetism which is led by the encapsulated Ce atom was slightly influenced by the carbene addition reaction. In addition, absolute position of the hydrogen atoms of the addend were assigned by the difference in the effective distance of the anisotropic magnetism, which is decreased with the cube of distance between the Ce and hydrogen atoms.
In this study, we have developed Ce@C82 derivatives that demonstrate a potential of EMFs for location recognition in molecular-scale. Five derivatives of Ce@C82 were successfully synthesized and isolated by a similar radical reaction that we reported recently.3 Addition position of the two isomers of them were unambiguously determined by a single crystal structure and/or characteristic absorption spectra. DFT calculations provide reasonable criteria to predict the addition position by the radical coupling reaction. The carbon atoms that have high SOMO density and positive charge are preferable for the addition position.
Temperature-dependent 1H-NMR measurements demonstrated unique paramagnetic shifts that are derived by the anisotropic magnetism of the Ce atom. And further analysis of the shifts revealed the dependency of the shift based on the distance and relative position from the Ce atom. This result indicates that the paramagnetic shifts provide location information of the addend. Therefore, Ce@C82 is capable to act as an molecular probe for location recognition of atoms by utilizing anisotropic magnetism of an EMF.
Reference:
1. T. Wakahara et al. J. Am. Chem. Soc.
2004, 126, 4883-4887.
2. Y. Takano et al. J. Am. Chem. Soc. 2009, 131, 9340-9346.
3. Y. Takano et al. J. Am. Chem. Soc. 2008, 130, 16224-16230.
(Invited) Chemical Purification of M3N Clusters in the Larger C88-C102 Cage
Authors: Stevenson Steven 
Published: February 2020

Since the discovery of Sc3N@C80 in 1999, much literature has focused on isolating metallic nitride clusters (M3N) entrapped within the smaller C80 cage. Over time, scientists (e.g., Echegoyen) have explored the same M3N clusters, but with bigger cage sizes, to expand the family of M3N@C2n. While HPLC has been the dominant method to isolate the larger M3N@C88-112, our research group is investigating non-chromatographic methods to purify M3N@C88-112
with the goal of disseminating these larger species to the scientific community. In this presentation, we demonstrate selective reactions of metallic nitride endohedrals present in soot extracts. Successful reagents include electron-poor Lewis acids and electron-rich amines. Combining these two reaction classes now permits the chemical purification of mixed-metal CeLu2N@C80 as an example of a C80 cage. Our most recent example of chemically isolating a metallic nitride in a larger cage is Gd3N@C88. Currently, we are spreading this purification method to transition metal and other rare-earth M3N clusterfullerenes.
(Invited) Controlling the Dipolar Coupling in Endohedral Fullerene-Phthalocyanine Dyads
Authors: Porfyrakis Kyriakos 
Published: February 2020

Paramagnetic endohedral fullerenes and phthalocyanine (Pc) complexes can be electron spin-active molecules. Hence they hold promise in applications where control of the electron spin properties is important such as spintronics and quantum information processing.
An important step towards these applications is the ability to tune the coupling between adjacent molecules. In this talk, I shall present our recent progress in the chemical functionalization of N@C60. I shall demonstrate how we have linked N@C60 and copper-phthalocyanine (CuPc) together, and characterized the resulting electron paramagnetic resonance properties, including the spin dipolar coupling between the fullerene spin and the CuPc spin. We were able to vary the distance between the two spin-active molecules and to interpret the distance-dependent coupling strength quantitatively. We then went one step further. We discovered an antiferromagnetic aggregation effect of the CuPc moieties and we demonstrated an extra facile method of tuning the dipolar coupling in such dyad systems: simply by adjusting the solution concentration. The solution concentration dependency opens a new way of tuning the dipolar coupling strength. We can turn on the dipolar coupling by diluting the sample, and turn off the dipolar coupling by concentrating the sample. I believe this to be the first step towards achieving exquisite spin-coupling control in future device architectures.
(Invited) Aligning Organic Dipolar Molecules in Carbon Nanotubes for Nonlinear Optics
Authors: Cambre Sofie , Campo Jochen , Beirnaert Charlie , Verlackt Christof C. , Wenseleers Wim 
Published: February 2020

The 1D character of single-walled carbon nanotubes (SWCNT) combined with their mechanical robustness, chemical inertness and wide range of diameters makes them ideal nanocontainers for various molecules. Here we show that by encapsulating elongated dipolar molecules in the 1D internal channel of SWCNTs, Coulomb interactions naturally favour a polar head-to-tail alignment of the molecular dipoles, resulting in a cooperative enhancement of directional properties, such as the dipole moment and the second-order nonlinear optical (NLO) response.[1] This principle is demonstrated for a prototypical dipolar molecule encapsulated in various SWCNT samples. The encapsulation is evidenced by extensive wavelength-dependent fluorescence-excitation and resonant Raman experiments on bile-salt solubilised dye-filled SWCNTs[2], revealing the effect of encapsulation on the vibrational and electronic properties of the SWCNTs and the encapsulated molecules.[3-6] The polar alignment is demonstrated by wavelength-dependent hyper Rayleigh scattering experiments (HRS)[7-9] (i.e. second harmonic light scattering). The newly synthesized organic nanohybrids possess a giant total dipole moment and NLO response, corresponding to ~70 identically aligned molecules (HRS intensity scaling quadratically with this number). These nanohybrids form solution processible building blocks highly interesting for the development of electro-optic modulators and switches.
References
[1] S. Cambré et al. Nature Nanotechnol. 10, 248 (2015)
[2] W. Wenseleers et al. Adv. Funct. Mater. 14, 1105 (2004)
[3] W. Wenseleers et al. Adv. Mater. 19, 2274 (2007)
[4] S. Cambré et al. Phys. Rev. Lett. 104, 207401 (2010)
[5] S. Cambré et al, ACS nano 6, 2649 (2012)
[6] S. Cambré et al. Angew. Chem. Int. Ed. 50, 2764 (2011)
[7] E. Goovaerts et al. In Handbook of advanced electronic and photonic Materials and Devices, Vol. 7: Nonlinear optical materials, Academic Press, San Diego, 127-191 (2001)
[8] J. Campo et al. Optics Express 17, 4587 (2009)
[9] J. Campo et al. J. Phys. Chem. Lett. .3, 2248 (2012)
Doped Lithium Orthosilicates - Promising High Rate Lithium-Ion Conductors for Li-S Batteries
Authors: Murugavel Shanthi Pavithra , Jampani Hanumantha Prashanth , Gattu Bharat , Velikokhatnyi Oleg I , Kumta Prashant N 
Published: February 2020

There is an increased demand for portable energy storage systems that demonstrate high efficiency. The current Li – ion battery system based on Li – graphite insertion chemistry has a theoretical capacity of 372 mAh/g. For Li – ion batteries to be implemented in portable energy devices, specific capacities twice than that of the current system is necessary.
Sulfur demonstrates a high theoretical specific capacity of 1672 mAh/g1
,
2, and is hence a promising candidate for high energy density lithium batteries. Moreover, sulfur is a low cost material and is easily available. Sulfur has very low conductivity (- 10-15 S/cm) which restricts the complete utilization of active material. Sulfur forms non – intercalation based polysulfide intermediates (Li2Sn ; n = 2 – 8)3which are soluble in liquid electrolyte resulting in loss of active material. In addition, the dissolved polysulfide gets coated onto the anode resulting in gradual cell voltage drop ultimately resulting in failure. These problems prevent the technology from being commercialized. Jampani et al. demonstrated reduced polysulfide dissolution and improved cycling stability by coating the sulfur cathodes with a lithium-ion conductor (LIC)4. The study identified Li4SiO4as a stable LIC. However, the application of this coating strategy is limited by the ionic conductivity of the LIC. In this work, the Li4SiO4 LIC was doped with dopants identified using first principles calculations by a high temperature solid state approach. The LIC was doped up to 5% without phase separation as represented in Figure 1. The doped LIC demonstrates a threefold increase in ionic conductivity as shown in Figure 2. This enhanced ionic conductivity is expected to improve the cycling stability of lithium-sulfur cathodes which will be discussed and presented in detail.
References
1. J. R. Akridge, Y. V. Mikhaylik and N. White, Solid State Ionics, 2004, 175, 243-245.
2. X. Ji and L. F. Nazar, Journal of Materials Chemistry, 2010, 20, 9821-9826.
3. C.-N. Lin, W.-C. Chen, Y.-F. Song, C.-C. Wang, L.-D. Tsai and N.-L. Wu, Journal of Power Sources, 2014, 263, 98-103.
4. P. J. Hanumantha, B. Gattu, O. Velikokhatnyi, M. K. Datta, S. S. Damle and P. N. Kumta, Journal of The Electrochemical Society, 2014, 161, A1173-A1180.

Figure 1
Activated Carbon Modified Electrodes for Soluble Lead-Acid Flow Batteries
Authors: Tang Hao-Lun , Chen Hsun-Yi 
Published: February 2020

A soluble lead-acid flow battery (SLFB) system is a promising energy storage technology for its several economic advantages such as free of ion exchange membranes and inexpensive active materials. However, state-of-the-art SLFBs have limited cycle life, which hampers their commercialization. Shedding of lead dioxide (PbO2) at the graphite anode during charging/discharging cycles has been identified as one of the primary reasons for the degradation of SLFBs, since the shed lead dioxide could not be reversed for current extraction. In addition, oxygen evolution or other side reactions can occur when the SLFB is charged at higher rates, which in turn leads to lower coulombic efficiency and limits the flow battery for higher power applications.
This study aims to extend the cyclability and increase the output power of SLFBs through modification of the graphite-based anode with activated-carbon addition. Activated carbon (AC) is known to have a high surface area and can perform capacitive behaviors when presents at the surface of an electrode during charge/discharge. Instantaneous current surge could thus be buffered when capacitive AC additives are employed in SLFBs. Moreover, addition of AC powders to a graphite electrode results in a higher total surface area per volume and will reduce local current densities. Since electroplating could induce dendrite formation because of surface instability, lower local current density could mitigate such instability and reduce shedding of PbO2 particles. Hence, the life time of SLFBs can be prolonged and the output power can be raised under the effects of AC additives.
To determine the most effective portion of AC additives, long-term charge/discharge experiments are conducted. We find the addition of 0.5wt% activated carbon to the graphite anode extends the cycle life of our SLFB system up to over 300 times, as shown in Figure1. However, the columbic efficiency is obsevered to be reduced by around 5% in comparison to the electrode with no additives. In addition to the lower conductivity resulted from the residual metal and impurities, this reduced voltage efficiency of SLFBs may result from the hydrophobic nature of activated carbon materials. This issue could be compensated by increasing the hydrophilicity of activated carbon through pretreatment. Several strategies of pretreatments are taken to remove the impurities and enhance hydrophilicity. Our work demonstrates that longer cycle life and higher power output are possibile to be achived in SLFBs.
Figure1. The charge/discharge efficiency of SLFBs with 0.5wt% activated carbon additive

Figure 1
Novel Vanadium Based Cation-Disordered Lithium Transition Metal Oxides for Li-Ion Batteries
Authors: Cambaz Musa Ali , Fichtner Maximilian 
Published: February 2020

Secondary lithium batteries are considered as a fundamental device for green and sustainable energy development and are now used as power sources for EV’s. However, the demand for higher energy density LIB’s necessitates the search for new materials and new systems.
Compounds with the ability to reversibly exchange more than 1 Li+ per formula unit are of great importance in order to achieve high specific capacities without undergoing severe chemical and structural changes. Prominent examples for multiple-electron transfer cathodes are Li2MSiO4 silicates, Li2M(PO4)F fluorophosphates[1] and Li2MTiO4 titanates.[2] The latter belongs to the class of cation-disordered rocksalt structure (spacegroup Fm-3m) with all cations disordered in the Wyckoff 4a site in the cationic sublattice. Up to now the practical capacities of disordered rocksalt titanates were restricted to 1e- transfer to about 150 mAhg-1. Vanadium-based positive materials are well known to possess a high capacity due to the ability of multiple redox-electron transfer. By the introduction of vanadium into the Li2MTiO4 Dominko et al [3] achieved reversible lithium intercalation-deintercalation beyond 1 Li+. Thus it appears, introducing vanadium into Li2M2O4 rock salt compounds is a promising approach in the search for new materials with high reversible capacity.
In this respect we synthesized a novel positive cathode material with disordered rock salt structure. The overall formula is Li2M2O4
with vanadium as one of the redox active transition metals within the structure. To the best of knowledge this compound has not been reported so far.
The XRD pattern of the as-prepared compound is shown in figure a) and can be indexed to cation-disordered cubic rock salt structure (space group Fm-3m) with the lattice parameter of a = 4.129 Å.

Figure b) is showing the charge-discharge profile for two different voltage windows. A narrow window between 3.5-1.0 V showing a reversible capacity of 170 mAhg-1. For an extended cycling window between 4.5-1.3 V a first discharge of around 245 mAhg-1is achieved. Figure c) shows the respective cycling performance. The OCV is around ~ 2.5 V vs Li/Li+. Various characterization techniques were applied to verify the redox process and reversible structural change upon electrochemical cycling.

References:

(1) Masquelier, C.; Croguennec, L. Chem. Rev.
2013, 113(8), 6552–6591.
(2) Sebastian, L.; Gopalakrishnan, J. J. Solid State Chem.
2003, 172(1), 171–177.
(3) Dominko, R.; Garrido, C. V. A.; Bele, M.; Kuezma, M.; Arcon, I.; Gaberscek, M. J. Power Sources
2011, 196 (16), 6856–6862.

Figure 1
Organic Redox Flow Batteries for Large-Scale Energy Storage
Authors: Hoober-Burkhardt Lena , Yang Bo , Krishnamoorthy Sankarganesh , Murali Advaith , Prakash G. K. Surya , Narayanan S. R. 
Published: February 2020

Energy storage is of paramount importance for integrating renewable energy sources into the grid. With energy storage systems, we can manage the intermittency that is inherent in solar photovoltaic and wind-based energy generation. To this end, we are studying an organic redox flow battery (ORBAT), based on water-soluble quinone and anthraquinone derivatives. ORBAT is a promising solution, as it has the potential to meet the demanding requirements for large-scale energy storage [1,2]. ORBAT is environmentally friendly, easily scalable, highly efficient, and has the potential to be inexpensive.
Quinones are ideal for an aqueous redox flow battery system not only because of their fast kinetics and high capacity, but also because they can be tuned for solubility and electrode potential. Addition of substituent groups affects not only solubility and electrode potential but also the kinetics and mechanism of the redox reactions. We will present the chemical and electrochemical properties of various molecules that were studied to understand the effect of substituents. We have studied these effects using electrochemical and spectroscopic techniques.
We will also present the most recent advances in performance resulting from improvements to the cell design that includes the flow field and electrode structure. We have been able to demonstrate current densities of nearly 300 mA/cm2 operating at 0.5 V (see Figure 1). Combining the understanding of the reaction kinetics of the redox molecules with the improved cell design provides a pathway to realizing the chemical reversibility, high efficiency and high power density needed for an ORBAT system to be useful for large-scale energy storage.

Acknowledgement:

The work presented here was funded by ARPA-E Open FOA (DE-AR0000353) and the University of Southern California, Los Angeles, CA.

References:

1) Yang, B.; Hoober-Burkhardt, L.E.; Wang, F.; Prakash, G.K.S.; Narayanan, S.R. J. Electrochem. Soc.
2014, 161, A1371
2) Yang, B.; Hoober-Burkhardt, L.E.; Prakash, G.K.S.; Narayanan, S.R. 227th ECS Conference, Chicago, Il (2015)

Figure 1
Highly-Active, Durable and Inexpensive Iron-Based Electrocatalyst for Oxygen Evolution
Authors: Mitra Debanjan , Yang Chenguang , Manohar Aswin K , Trinh Phong , Narayanan S. R. 
Published: February 2020

Development of inexpensive, efficient and robust electrocatalyst for oxygen evolution reaction (OER) is an essential requirement for various large scale energy storage and conversion applications, such as, metal-air rechargeable batteries and regenerative fuel cell. [1] Ru and Ir precious metal-based electrocatalysts are well-known to exhibit good catalytic activity towards OER but high cost and rare abundance of these materials preclude their wide-scale deployment in industrial energy storage applications. In the quest for finding inexpensive as well as active catalysts for OER, we have been investigating perovskites and spinel structures containing transition metals, such as, iron, nickel, cobalt, manganese recently. [2,3,4] Despite these efforts, finding an inexpensive elecrocatalyst for OER with a lower overpotential and high durability comparable with precious metal based catalysts has still remained a challenge to the scientific community.
Here, we report a cost-effective electrocatalyst based on a sintered iron (NSI) electrode modified by thermal decomposition of nickel. We have found such an electrode to be an active and robust electrocataylyst for oxygen evolution in aqueous alkaline medium. To the best of our knowledge this is the first time that iron is used as a substrate to yield a highly robust and durable structure with an exceptionally high electrocatalytic activity. We have obtained 230 mV overpotential at 10 mA/cm2 (Figure 1 a). The same electrode exhibits a highly stable overpotential for 230 hours (Figure 1 b). We have also studied the effects of decomposition temperature of preparation of the NSI catalysts on their activity towards OER. Our study shows that the NSI electrode prepared at 2000 C exhibits a different surface than prepared at 4000 C and is more favorable for OER. We have investigated surface composition using physical characterization methods such as XRD and XPS. We have also investigated the electrochemical kinetics for oxygen evolution through steady-state voltammetry.

References:

S. R. Narayan, A. K. Manohar and S. Mukerjee, Electrochem. Soc. Interface, 24.2 (2015): 65-69.

S. Malkhandi, B. Yang, A. K. Manohar, A. Manivannan, G. K. S. Prakash and S. R. Narayanan, J. Phys. Chem. Lett., 3, 967 (2012).

S. Malkhandi, P. Trinh, A. K. Manohar, A. Manivannan, M. Balasubramanian, G. K. S. Prakash and S. R. Narayanan, J. Phys. Chem. C, 119(15), 8004-8013 (2015).

P. Trinh, S. Malkhandi, A. K. Manohar, A. Manivannan and S. R. Narayanan, ECS., (2015, July) In Meeting Abstracts (No. 1, pp. 25-25).

Figure 1
Anthraquinone Functionalized Reduced Graphene Oxide As Electrode Material for Rechargeable Batteries
Authors: Esat Burak , Bahceci Sumeyye , Momchilov Anton Angelov 
Published: February 2020

The ever-increasing demand for high-performing, light weight, economical, and safe power storage for high–tech portable devices and electric vehicles leads to augmented research efforts in the field of organic or organic/hybrid materials to be used as electrodes in energy storage devices [1-14]. An anode material based on anthraquinone-functionalized reduced graphene oxide (AQ-RGO) is synthesized and its electrochemical properties have been investigated. The initial studies against Li metal revealed that a quite reversible capacity of 200 mAh/g was obtained based on the weight of electro-active anthraquinone moieties when cycled between 1.8and 3.2 V at 0.3C rate. The energy density was found to be around 450 mWh/g. The AQ-RGO has been used also as an anode material against in an aqueous battery against NiOOH (AQ-rGO | 30% NaOH | NiOOH). This battery provided a capacity of 140 mA/h at 0.83V.

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Figure 1