bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Exploration of Short DNA Sequences Toward Complete Resolution of Single-Chirality SWCNTs
Authors: Lin Zhiwei , Yang Yoona , Sharma Arjun , Jagota Anand , Zheng Ming
Published: July 2021

Sequence-dependent interactions between DNA and single-wall carbon nanotubes (SWCNTs) have been shown to provide resolution for the atomic-structure-based sorting of DNA-wrapped SWCNTs by their helicity and handedness. Although significant progress has been made on DNA sequence selection for sorting SWCNTs, DNA sequence screening so far is still a high-cost, time-consuming and inefficient process. The success rate of finding recognition sequences is rather low (~10%), and it remains a grand challenge to predict recognition sequence patterns for sorting SWCNTs. Aiming to conquer this challenge, we have developed a highly efficient approach of finding recognition sequences by machine-learning guided experimental exploration of DNA sequence space. In this contribution, we present experimental data from short DNA sequences consisting of 5 and 6 nucleotides (referred to as 5-mers and 6-mers). Selective short DNA sequences demonstrate remarkable sorting resolution toward single-chirality SWCNTs, giving rise to more than 20 highly pure species. Since the short DNA sequences possess plain pattern combination and a relatively small number of distinct members of their population, we are able to explore the entire sequence space to address recognition pattern. Finally, we combine experimental investigation and machine learning to develop a highly efficient approach to differentiate recognition and nonrecognition sequences with success rate of > 90%.
(Invited) Charge-Carrier Localization in Doped Semiconducting Carbon Nanotubes Revealed By IR- and EPR Spectroscopy
Authors: Eckstein Klaus , Auth Michael , Oberndorfer Florian , Sperlich Andreas , Dyakonov Vladimir , Hertel Tobias
Published: July 2021

IR and EPR spectroscopic investigations of redox- p-doped semiconducting (6,5) single-wall carbon nanotubes (s-SWNTs) were used to study carrier localization and delocalization from low- up to degenerate doping levels. At low carrier concentrations, the analysis of IR-intraband transitions as well as the appearance of a doping-induced vibrational D-band anti-resonance, point to charge-localization on the few nm length-scale. Moreover, the rise of a spin 1/2 signal in EPR closely tracks the increase of the doping level, supporting the notion of charge-localization at low carrier concentrations. At doping levels exceeding 0.1 nm-1, EPR data as well as intra- and D-band absorption in the IR point to antiferromagnetic coupling between surplus charge carriers becoming dominant. These results are expected to be relevant for field- or redox-chemical doping of s-SWNTs in any polarizable, heterogeneous environment.
(Invited) DNA-Directed High-Precision Assembly of High-Performance CNT FETs
Authors: Sun Wei , Zhao Mengyu , Chen Yahong , Zhu Zhi , Zheng Ming
Published: July 2021

Precise fabrication of semiconducting channel materials into densely-aligned uniform arrays is one prerequisite towards the high-performance ultra-scaled technology nodes, in particular for carbon nanotubes (CNTs). Traditional thin-film approaches generally yield CNTs in irregularly-spaced bundles or with wide orientation distribution, and lack a mechanism to effectively eliminate the mis-aligned CNTs from the ultra-scaled channel area. Therefore, the averaged pitch value and precision of CNT arrays, the key parameters defining lateral CNT spacing, fail to simultaneously meet all of the patterning requirements for the ultra-scaled technology nodes. Bio-fabrication is promising for patterning CNTls at a resolution beyond the existing lithographic limit. However, impacted by surface charges and sub-micron dimensions of typical bio-templates, current bio-templated electronics exhibit both poor transport performance and array uniformity smaller than 1 micron.

We report precise scaling of inter-CNT pitch using a supramolecular assembly method called Spatially Hindered Integration of Nanowire Electronics (SHINE). Specifically, by using nano-trenches to align CNTs and DNA hybridization to stabilize them in place, we constructed parallel CNT arrays with uniform pitch as small as 10.4 nm, at an assembly yield over 95%. The pitch precision improves on that prepared from conventional thin-film approaches by more than two orders of magnitude. Compared to the lithography-patterned Si channels at 10 nm technology node, SHINE simultaneously provides both 70% smaller averaged pitch value and molecular-scale pitch precision in the channel area. By engineering the interfacial compositions, metal ions and surface charges that are destructive to FET performance have been excluded from the channel area without degrading CNT alignment. Under a source-to-drain voltage of -0.5 V, we demonstrate both transconductance more than 0.6 mS/μm with fast on/off switching. And the key FET performance metrics are improved by more than one order of magnitude than previous bio-templated FETs. Furthermore, we demonstrate centimeter-scale alignment of fixed-width CNT arrays. At the interface of high-performance electronics and bio-molecular self-assembly, precise bio-fabrication could provide ultra-scaled devices or circuits compatible with or sensitive to local biological environments.
(Invited) Molecularly Selective Filling of a Tight Nanotube Pore
Authors: Qu Haoran , Rayabharam Archith , Wu Xiaojian , Wang Peng , Li Yunfeng , Fagan Jeffrey , Aluru Narayan R. , Wang YuHuang
Published: July 2021

Molecular sieving occurs when a smaller molecule selectively enters the nanopore. Contrary to this understanding, we find that single-wall carbon nanotubes with a van der Waals pore size of just 0.42 nm readily separate n-hexane from cyclohexane—despite the fact that both molecules are larger than the rigid nanopore. This unexpected observation challenges our current understanding of nanopore selectivity and how molecules may enter a tight channel. In this talk, we will discuss a joint experimental and theoretical study on this phenomenon. The insights may open up new opportunities to engineer nanopore selectivity based on the molecular degrees of freedom.
Kinetics and Thermodynamics Driven Charging Protocols to Control the Formation of Dendrites in the Rechargeable Batteries
Authors: Aryanfar Asghar , Goddard William
Published: July 2021

The instigation and growth of the dendritic microstructures during the charging period is a multi-physics phenomena, hindering the longevity and safety measures in rechargeable batteries. Inspired by the dynamics of the ionic motion and the energetics of the bond formation, we develop new optimized intermittent charging forms which minimize the branching tendency, leading to formation of higly compact dendrites. Subsequently we perform molecular dynamics simulaitions to visualize, measure and verify the analytically-obtained dendritic tendency trends. In practice, such patterns could get programmed into the charger for safe-charging and boosting the sustainability in next-generation rechargeable batteries, particularly for those of using metallic electrode.

Figure 1
Roles of Ionic Transport in Dendrite Growth through Solid State Electrolytes at the Critical Current Density
Authors: Gopal Rajeev , Bai Peng
Published: July 2021

Lithium metal anodes hold the promise to significantly increase the energy density of current Li-ion batteries by replacing the bulkier graphite anode. However, these batteries have low cycling efficiency and internal short circuiting due to metal dendrites. A strategy to prevent dendritic growth is using a stiff solid electrolyte that can mechanically block their growth, while in reality, penetration through the tough solid electrolytes by soft Li metal filaments still occurs at a relatively low critical current density.

Inspired by the dendrite initiation at the system-specific limiting current in liquid electrolytes, we explore the possibility in this study that dendrite growth in solid state electrolytes at the critical current density (CCD) is a transport limited phenomenon determined by ionic conduction. Previous studies have used galvanostatic cycling [1] as the basis for measuring the CCD, however cycling presents problems of interfacial stripping and delamination leading to a reduction in contact surface area and high localized current densities. Here we use linear sweep voltammetry (LSV) with the implementation of stack pressure to mitigate these effects to initially determine the CCD and develop a model connected to the ionic conduction. With the experimentally determined CCD, we then investigate the penetration time at various higher-than-CCD constant current densities to uncover a Sand’s time-like behavior, which offers insights on the transport dynamics consistent with our previous work [2]. Operando and postmortem analyses were also performed to complement the electrochemical characterization toward a self-consistent comprehensive understanding. In conclusion, our new method allows us to understand the growth mechanism of dendrites in solid electrolytes, while still connecting microstructural and interfacial aspects from previous published works[3][4], to present a unified approach to understanding the metal dendrite initiation at the CCD.

References

E. Kazyak, R. Garcia-Mendez, W.S. LePage, A. Sharafi, A.L. Davis, A.J. Sanchez, K.-H. Chen, C. Haslam, J. Sakamoto and N.P. Dasgupta. Li Penetration in Ceramic Solid Electrolytes: Operando Microscopy Analysis of Morphology, Propagation, and Reversibility. Matter 2, 1025-1048, (2020).

P. Bai, J. Li, F.R. Brushett and M.Z. Bazant. Transition of lithium growth mechanisms in liquid electrolytes. Energ Environ Sci 9, 3221-3229, (2016).

L. Porz, T. Swamy, B.W. Sheldon, D. Rettenwander, T. Frömling, H.L. Thaman, S. Berendts, R. Uecker, W.C. Carter and Y.-M. Chiang. Mechanism of Lithium Metal Penetration through Inorganic Solid Electrolytes. Advanced Energy Materials 7, 1701003-n/a, (2017).

T. Krauskopf, H. Hartmann, W.G. Zeier and J. Janek. Toward a Fundamental Understanding of the Lithium Metal Anode in Solid-State Batteries—An Electrochemo-Mechanical Study on the Garnet-Type Solid Electrolyte Li6.25Al0.25La3Zr2O12. ACS Applied Materials & Interfaces 11, 14463-14477, (2019).

Figure 1
(Invited) Synthesis and Optical Properties of Graphene Quantum Dots
Authors: Lavie Julien , Medina Lopez Daniel , Liu Thomas , Rondin Loic , Latil Sylvain , Lauret Js , Campidelli Stephane
Published: July 2021

The outstanding electronic, optical and mechanical properties of graphene strongly inspire the scientific community at both the fundamental and applicative levels. However, the key issue that needs to be addressed is the control and the modification of the electronic properties of graphene, and notably the opening of a sizable bandgap. For the last decade, a great attention has been paid to the size reduction of graphene using conventional top-down approaches (lithography and etching, thermal treatments and oxidation of bulk materials) to fabricate graphene quantum dots (GQDs)1 or graphene nanoribbons (GNRs).2 However, top-down approaches do not permit to manipulate the structure of the material at the atomic scale. In particular, they do not allow a sufficient control of the morphology and oxidation state of the edges, which drastically impact the properties. In order to truly control, with the required level of precision, the morphology and the composition of the materials and of its edges, the bottom-up approach is the relevant way to proceed.3,4

Recently, we reported on the synthesis and single photon emission properties of triangular-shaped GQDs.5 While, this initial report focused on functionalized nanoparticles, we now turn to non-functionalized graphene quantum dots that are in terms of structure closer to real graphene. Here, we described the synthesis, the dispersion and optical properties of a series of rod-shaped particles and we studied the structure-properties relationship in these graphene quantum dots. To this end, we designed a series of GQDs with a given edge type and by changing only one parameter (one dimension, namely the length or the width – Figure), we expect to follow simply the evolution of the optical properties.

References.

Haque, E.; Kim, J.; Malgras, V.; Reddy, K. R.; Ward, A. C.; You, J.; Bando, Y.; Hossain, M. S. A.; Yamauchi, Y. Recent Advances in Graphene Quantum Dots: Synthesis, Properties, and Applications. Small Methods
2018,
2, 1800050.

Xu, W.; Lee, T.-W. Recent progress in fabrication techniques ofgraphene nanoribbons. Mater. Horiz.
2016,
3, 186-207.

Narita, A.; Wang, X. Y.; Feng, X.; Müllen, K. New advances in nanographene chemistry. Chem. Soc. Rev.
2015,
44, 6616-6643.

Narita, A.; Chen, Z.; Chen, Q.; Müllen, K. Solution and on-surface synthesis of structurally defined graphene nanoribbons as a new family of semiconductors. Chem. Sci.
2019,
10, 964-975.

Zhao, S.; Lavie, J.; Rondin, L.; Orcin-Chaix, L.; Diederichs, C.; Roussignol, P.; Chassagneux, Y.; Voisin, C.; Müllen, K.; Narita, A.; Campidelli, S.; Lauret, J.-S. Single photon emission from graphene quantum dots at room temperature. Nat. Commun.
2018,
9, 3470.

Figure 1
(Invited) The Electroluminescence of Graphene
Authors: Baudin Emmanuel , Schmitt Aurélien , Mele David , Abou Hamdan Loubnan , Voisin Christophe , Plaçais Bernard , De Wilde Yannick
Published: July 2021

Electroluminescence is the phenomenon by which a material emits light in response to the passage of an electric current. In solids, it is the prerogative of semiconductors and related organic materials, and it results from the radiative recombination of electrons and holes. Today, electroluminescent devices represent the majority of lighting and display devices and are a building block of the global information and telecommunication network.

We report on two observations signaling the electroluminescence of high-mobility graphene field-effect transistors (FET). The semi-metallic nature of graphene a priori forbids electroluminescence: Indeed, in semiconductors, the bandgap energetically insulates the electrons from the holes. Such protection doesn’t exist in graphene which is gapless. Nonetheless, electroluminescence is possible, because (i) of the remarkable inefficiency of the non-radiative carrier relaxation in graphene, and (ii) thanks to an original carrier injection mechanism specific to 2D semimetals: the Zener-Klein (ZK) tunnel conductance. [1]

Our first observation consists in the thermometry of graphene’s electrons with applied bias, see figure 1a. Using electronic noise thermometry, we observe that, after an initial warm up with the deposited Joule power, the electron gas cools down, starting at a doping-dependent threshold. The turning point is concomitant with the onset of electron-hole injection by Zener-Klein (ZK) tunneling. The cooling mechanism involves the radiative emission, due to the electron-hole recombination, in electromagnetic near-field modes of the hBN-graphene heterostructure. It is reminiscent of far-field electroluminescent cooling that can be observed in regular LEDs [2] except that it’s much more efficient (~10 mW vs. ~10 pW, i.e., 9 orders of magnitude larger). [3]

Our second observation consists in the detection of the middle-wave infrared radiation (MIR) emitted by a high-mobility graphene FET operating in ambient conditions, see figure 1b. We observe a sizeable optical emission in the range 80–250 meV, starting at the ZK tunneling threshold bias. The spectral analysis of the emitted light indicates that it originates from the scattering of the hBN-graphene heterostructure near-fields, as observed in reference [4] by surface near-field optical microscopy.

Bibliography

[1] W.
Yang et al,
A graphene Zener-Klein transistor cooled by a hyperbolic substrate. Nat. Nanotechnol. 2018, Vol. 47, 13.

[2] P. Santhanam et
al, Room temperature thermo-electric pumping in mid-infrared light-emitting diodes. Appl. Phys. Lett. 2013, Vol. 103, 18, p. 183513.

[3] E.
Baudin et al,
Hyperbolic Phonon Polariton Electroluminescence as an Electronic Cooling Pathway. Adv. Funct.. Mater. 2020, Vol. 30, 8, p. 1904783.

[4] S. Dai et al, «
Graphene on hexagonal boron nitride as a tunable hyperbolic metamaterial ». Nat. Nanotech. 2015, Vol. 10, 8, p. 682.

Figure 1
(Invited) Experimental Quantum Transport in Strained Graphene and SWCNTs - Towards Noems
Authors: Champagne Alexandre R
Published: July 2021

We measure ballistic charge conductivity in strained suspended graphene and observe the theoretically predicted [1] strain-induced scalar and vector potentials. To do so, we built an experimental platform for in-situ quantum transport strain engineering in 2D materials. This instrumentation also permits low temperature (0.3 K) transport in 0 to 9 Tesla magnetic fields. The tunable uniaxial strain (up to 3%) is completely decoupled from the gate-tunable charge density, permitting quantitative understanding of strain effects. We show slippage-free mechanical clamping of high aspect-ratio graphene crystals, where atomically ordered edges are unnecessary for quantitative straintronics. We study in detail transport in a ballistic graphene channel whose length is 90 nm and width is 600 nm. By applying strain up to 0.6 % in this device, we observe that the strain-induced scalar potential shifts its low energy band structure downward by up to 30 meV. We show precise control of the gauge vector potential which reversibly suppresses the conductance. We discuss our progress towards strain engineering in SWCNTs, and calculations showing its potential in valley filtering and tuning electron-hole asymmetric quantum transistors.

We conclude with an overview of another project to integrate suspended bilayer graphene devices in planar optical cavities towards achieving fully tunable nano-opto-electro-mechanical (NOEMS) carbon systems. To do so, we discuss a nitrocellulose-based dry-stamping method to manipulate and suspend individual 2D materials [2]. Using this method we assembled optical cavities able to a widely tune Raman scattering and absorption in graphene. [1] A. C. McRae, G. Wei, and A. R. Champagne, Phys. Rev. Applied 11, 054019 (2019). [2] I. G. Rebollo, F. C. Rodrigues-Machado, W. Wright, G. J. Melin, A. R. Champagne, ArXiv:2011.14166

Figure 1
(Invited) 1D Confinement of Dyes inside Boron Nitride Nanotubes: Photo-Stability and Aggregation Effects
Authors: Gaufres Etienne
Published: July 2021

The encapsulation of organic molecules inside nanotubes forms a class of nano-heterostructures with optical properties driven by the 1D properties of the nanotube host template.

When confined and aligned inside a carbon nanotube (CNT), organic dyes (e.g. sexithiophene) exhibit for instance a strong Raman signal and a quenched fluorescence by the CNT [1-3]. Here we show that boron nitride nanotubes (BNNTs) having inner diameters between 1 nm to 5 nm provide similar 1D confinement effects with the difference that the BNNTs (Eg~5 eV) preserve the luminescence of the dyes. Experiments on individual and assembly of Dyes@BNNT demonstrate that the walls of the BNNTs provide protection to the dyes against photobleaching under continuous photo-excitation in ambient conditions. High Resolution Transmission Electron Microscopy on Dyes@BNNTs shows ordered aggregation of the encapsulated depending on the BNNT diameter. [4] Finally, fluorescence imaging and spectroscopy on Dyes@BNNTs reveal that the emitted light is highly polarized along the nanotube axis with extinction ratios of ~700 at room temperature. Both absorption and emission energies are strongly red-shifted compared to non-encapsulated dyes. That is, a shift as high as 0.8 eV between DPP2 dyes and DPP2@BNNT fluorescence has been observed, which allows a tuning of the dye optical activity from the visible to near-infrared (NIRII).

Work done in collaboration with C. Allard, A. Badon, L. Schué, F. Fossard, L.Cognet, G. Recher,R. Nascimento, E. Flahaut, P. Desjardins, R. Martel and A. Loiseau

[1] E. Gaufrès et al Nature Photon. 8, 72-78 (2014)

[2] S. Cambré et al Nature Nano. 10, 248-252 (2015)

[3] E. Gaufrès et al ACS Nano, 10, 11 (2016)

[4] C. Allard et al, Advanced Materials, 32, 29 (2020)
Big Data for Li-Ion Diagnosis and Prognosis
Authors: Dubarry Matthieu , Beck David
Published: July 2021

Accurate lithium battery diagnosis and prognosis is critical to increase penetration of electric vehicles and grid-tied storage systems. Both diagnosis and prognosis are complex due to the intricate, nonlinear, and path-dependent nature of battery degradation. Data-driven models are anticipated to play a significant role in the behavioral prediction of dynamical systems such as batteries. However, they are often limited by the amount of training data available.

In this work, we will present the application of a proof-of-concept methodology to generate big data training datasets for intercalation batteries. We will use a mechanistic approach that combines both modeling and experimental techniques to provide a universal tool for the creation of synthetic voltage curves practically indistinguishable from real data. This approach offers the benefits of the broad applicability of the model to various cell chemistries, designs, and operating modes, as well as the high fidelity. The methodology could be applied to the generation of training datasets encompassing the entire degradation spectrum as well as different operating conditions such as rate and temperature. Scenarios leading to lithium plating with adjustable reversibility can also be added and the addition of random noise on the data could be considered to make the datasets even more realistic and consider the impact of real-life testing machines' precision and accuracy

The public proof-of-concept datasets are over three orders of magnitude larger than what is currently available in the literature. This will expend critical capabilities of current AI algorithms, tools, and techniques to predict scientific data. The synthetic datasets will cover the entire spectrum of possible degradations and degradation paths for several battery chemistries. These complete datasets are unprecedented and they will be used to identify meaningful learning parameter by comparing and evaluating different features of interest on the voltage curves to understand the relationship between data and model. For example, early prognosis conditions will be tested to establish whether a single point early prognosis is possible.
Bipolar Redox-Active Molecules: Coupling Structure and Cycling Engineering in Extending Cycling Longevity
Authors: Li Min , Minteer Shelley
Published: July 2021

Non-aqueous organic redox flow batteries (NAqORFBs) have shown great potential in grid-scale energy storage as a result of their wide potential windows (up to ~ 5 V) and a variety of abundant electroactive molecules, making high energy densities possible. Among organic redox-active materials developed, bipolar redoxmers (BRMs), single molecules that can be used as both anolyte and catholyte, stand out as a distinct class of electroactive species. Their unique redox chemistry enables identical components present in RFBs, which has distinct advantages in storage, mitigating crossover and compound degradation – yet the development of robust BRMs is still in its early stage and many important challenges remain to be addressed. Here we aim to fill this gap by evaluating their structure-property relationship and potential of extending cycling lifetime by utilizing both cathodic and anodic molecules. Such studies have uncovered unexpected structure-property responses and identified essential elements in completing their distinct benefits in cycling longevity.
(Nanocarbons Division Best Poster Award - 1st Place) Chemical Purification and Isolation of New Fullertube Molecules
Authors: Ashcroft Chloe Annemarie , Koenig Ryan M , Noble Cora , Sedlaczek Angelina , Stevenson Steven
Published: July 2021

The fullertubes represent an exciting new type of molecular carbon. This unique structure consists of a nanotube belt similar to a rolled graphene substructure, but with two fullerene based endcaps. The demand for purified fullertubes is based on the excitement of application development and fundamental research. Regardless of the desired experiment, the first requirement is to obtain isomerically purified fullertubes. In this presentation, we discuss the separation challenges and solutions to these technical hurdles. We have overcome the low fullertube abundance in soot extract by a chemical based enrichment. In this selective reaction, spheroidal fullerenes are reacted and removed from solution. The unreacted fullertubes remain in solution and are enriched by several orders of magnitude. This precleanup step is critical and should be scalable to industry.
Fundamental Study of the Dispersion of Carbon Nano-Onions
Authors: Nieves-Carrasquillo Armando Junior , Del Valle-Perez Angelica , Cunci Lisandro
Published: July 2021

Since the discovery of the fullerene C60 in 1985 by Curl, Kroto and Smalley, carbon nanomaterials have been the focus of interdisciplinary chemical research. Multi-shell fullerenes, known as carbon nano-onions (CNOs) discovered by Ugarte in 1992, are structured by concentric shells of carbon atoms. Different methods for their synthesis have been developed and their properties have been widely studied. In addition, the chemical functionalization of CNOs has been investigated and several synthetic pathways were found to be applicable for the introduction of a variety of functional groups. The purpose of this project is to make the oxidized CNOs bear a relative centrifugal force at different time durations to analyzed how well the material disperses. This in turn, will provide a fundamental concept for the synthesis efficiency. According to preliminary results, there is a tendency on which the concentrated CNOs difference in weight gets narrow, as duration of the centrifugal force increases. Chemically modified CNOs were probed in different fields of application and have revealed to be a promising nanomaterial that attracts a growing interest among researchers and opens new avenues for investigation. Its development starts using nano-diamonds; a carbon nanomaterial of strong structure which undergoes through a temperature of approximately 1650°C inside a furnace to obtain the CNOs structure. The CNOs are then oxidize through synthesis that requires a constant temperature and stirring to attain oxygen based functional groups. Another way to obtain the oxygen based functional groups is through heating the sample at 400°C for two hours; these procedures are then analyzed to determine the efficiency of functionalization. The preliminary elemental detection of oxygen atoms was gathered by Energy-Dispersive Spectroscopy. To detect states in the CNO’s molecular system, Raman Spectroscopy was utilized to confirm the carbon structure of CNOs by the identification of the peaks D and G characteristic of this carbon material. An in-depth characterization analysis was done using X-Ray Diffraction, providing detailed information about chemical composition, and crystalline structure. The morphology and microstructure of CNOs were studied using a Transmission Electron Microscope and Scanning Electron Microscopy. Through Cyclic Voltammetry, CNO’s ink was prepared to characterize electrochemically comparing both functionalization processes. To study its catalytic properties, Oxygen Reduction Reaction (ORR) experiments was conducted utilizing Rotating Ring-Disk Electrode (RRDE). The ORR experiments were carried out by varying the rotation rates of the RRDE at 100, 400, 900, 1600 and 2500 rpm.
(Invited) Electrochemical Functionalizations of [60]fullerene-fused Lactones
Authors: Wang Guan-Wu , Niu Chuang
Published: July 2021

[60]Fullerene-fused lactones can be electrochemically reduced under controlled potential electrolysis (PCE) to generate the corresponding dianionic species. The generated dianionic [60]fullerene-fused lactones are then treated with acids and different electrophiles to afford the [60]fullerene-fused ketones, alkylated 1,2- and 1,4-adducts, and cyclic adducts with a medium or large ring.
(Invited) Syntheses of Novel Dysprosium-based Metal Cyanide Clusterfullerenes by Using Solid Cyanide Sources
Authors: Yang Shangfeng
Published: July 2021

Metal cyanide clusterfullerenes (CYCFs) represent the only endohedral clusterfullerenes with merely one metal atom encapsulated. So far all of the reported CYCFs are synthesized by using gaseous N2 as the cyanide source, whether solid cyanide source can be applicable for syntheses of CYCFs remains an open question. In this work, we developed several solid cyanide sources, and succeeded in synthesizing novel dysprosium (Dy)-based metal cyanide clusterfullerenes in high yield. The molecular structures of three isomers of DyCN@C82 are unambiguously determined by single-crystal X-ray diffraction, indicating that the encapsulated triangular DyCN cluster is tunable due to the strong metal-cage interactions.
(Invited) Novel Dysprosium-Based Metalloazafullerenes: Syntheses, Structures and Properties
Authors: Wang Yuanyuan , Shi Zujin
Published: July 2021

Substituting a carbon atom on the carbon cage (C2n) by nitrogen can lead to a special kind of fullerene called azafullerene (C2n-1N), which tends to form a dimer due to its paramagnetic property. When an azafullerene monomer, acting as a nanocontainer, encounters metal atoms or clusters, the extra electron generated by the nitrogen substitution would be transferred to the internal metal or cluster center. This may lead to the enhancement of metal-metal interaction, the capture of metastable species and concomitantly some interesting chemical and physical properties.

Here, we have synthesized and crystallographically characterized two novel metalloazafullerenes Dy2@C79N and Dy2N4@C81N with quasi-C80-Ih
(7) and quasi-C82-C
3v
(8) cages, respectively. Owing to the strong exchange coupling between two dysprosium ions via radical bridges, Dy2@C79N behaves as an excellent single-molecule magnet with large energy barrier of U = 669 ± 7 K and observable hysteresis loops below 24 K. Dy2N4@C81N is the first entity of capturing the unstable four-membered nitrogen ring (cyclo-N4) with definitive structure characterized by single-crystal x-ray diffraction (XRD) analysis. The results show that a planar cyclo-N4 coordinated with two dysprosium ions to form a distorted octahedral cluster inside the C81N cage. These works will inspire further exploration of the properties and applications of metalloazafullerenes.

Keywords: Metalloazafullerene; Single-molecule magnet;
Four-membered
nitrogen ring

References:

[1] G. Velkos; D. S. Krylov; K. Kirkpatrick; L. Spree; V. Dubrovin; B. Buchner; S. M. Avdoshenko; V. Bezmelnitsyn; S. Davis; P. Faust; J. Duchamp; H. C. Dorn; A. A. Popov, Angew. Chem. Int. Ed., 2019, 58, 5891-5896.

[2] Z. Hu; B. W. Dong; Z. Liu; J. J. Liu; J. Su; C. Yu; J. Xiong; D. E. Shi; Y. Wang; B. W. Wang; A. Ardavan; Z. Shi; S. D. Jiang; S. Gao, J. Am. Chem. Soc., 2018, 140, 1123-1130.

[3] Y. Wang; J. Xiong; J. Su; Z. Hu; F. Ma; R. Sun; X. Tan; H. L. Sun; B. W. Wang; Z. Shi; S. Gao, Nanoscale, 2020, 12, 11130–11135.
(Invited) The Varying Packing Behaviors of Tb@C82 (I, II) Isomers in Their Cocrystals with Ni(OEP)
Authors: Dong Wei , Lian Yongfu
Published: July 2021

Carbon soot containing terbium endohedral fullerenes was prepared by vaporizing a graphite rod doped with Tb4O7 in an electric arc-discharge chamber. After Soxhlet extraction with 1,2,4-trichlorobenzene and rotary evaporation, the obtained residue was ultrasonically dissolved in toluene and then subjected to a three-stage high-pressure liquid chromatographic (HPLC) isolation process to collect the Tb@C82 (I, II) isomers. The molecular structures of Tb@C82 (I, II) are unambiguously characterized as Tb@C
2v(9)-C82 and Tb@C
s(6)-C82, respectively, in line with single-crystal X-ray diffraction. Moreover, Tb@C82 (I, II) isomers demonstrated different packing behaviors in their cocrystals with Ni(OEP). Tb@C82 (I) forms 1:1 cocrystal with Ni(OEP), whereas Tb@C82 (II) forms 2:2 cocrystal with Ni(OEP). Tb@C
s(6)-C82 forms a centrosymmetric dimer in 2[Tb@C
s(6)-C82]∙2[Ni(OEP)]∙2(C6H6)∙(CS2), and the two C
s(6)-C82 cages are connected by a new C-C bond with a bond length of 1.618(4) Å. Density functional theory calculations show that the dominant unpaired spin exists on a particular C atom of Tb@C
s(6)-C82, leading to regionally selective dimerization.
(Invited) Synthesis, Isolation, and Derivatization of Dimetallofullerenes
Authors: Wang Yaofeng , Liu Fupin , Popov Alexey A.
Published: July 2021

Dimer of Sc, Y, or lanthanide encapsulated inside fullerene cages (known as dimetallofullerenes, or di-EMFs) presents very interesting interplay between the two metal ions as well as metal ions and fullerene cage.1-3 Recently, very strong coupling between two metal ions through single electron metal-metal bonding is proved to be vital for their outstanding magnetic properties such as high blocking temperatures for Tb2@C80-CH2Ph and Dy2@C80-CH2Ph,4-5 and long spin dephasing time for Sc2@C80-CH2Ph.6 However, these molecules are elusive, caused by their characteristic electronic properties, which can be isolated after derivatization.3 In this contribution, very recent progress in the synthesis, isolation, and derivatization of di-EMFs will be discussed.

Popov, A. A.; Avdoshenko, S. M.; Pendas, A. M.; Dunsch, L., Bonding between strongly repulsive metal atoms: an oxymoron made real in a confined space of endohedral metallofullerenes. Chem. Commun.
2012,
48, 8031-8050.

Popov, A. A.; Yang, S.; Dunsch, L., Endohedral Fullerenes. Chem. Rev.
2013,
113, 5989-6113.

Liu, F.; Spree, L.; Krylov, D. S.; Velkos, G.; Avdoshenko, S. M.; Popov, A. A., Single-Electron Lanthanide-Lanthanide Bonds Inside Fullerenes toward Robust Redox-Active Molecular Magnets. Acc. Chem. Res.
2019,
52, 2981-2993.

Liu, F.; Velkos, G.; Krylov, D. S.; Spree, L.; Zalibera, M.; Ray, R.; Samoylova, N. A.; Chen, C.-H.; Rosenkranz, M.; Schiemenz, S.; Ziegs, F.; Nenkov, K.; Kostanyan, A.; Greber, T.; Wolter, A. U. B.; Richter, M.; Büchner, B.; Avdoshenko, S. M.; Popov, A. A., Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal–metal bond. Nat. Commun.
2019,
10, 571.

Liu, F.; Krylov, D. S.; Spree, L.; Avdoshenko, S. M.; Samoylova, N. A.; Rosenkranz, M.; Kostanyan, A.; Greber, T.; Wolter, A. U. B.; Büchner, B.; Popov, A. A., Single molecule magnet with an unpaired electron trapped between two lanthanide ions inside a fullerene. Nat. Commun.
2017,
8, 16098.

Zaripov, R.; Kandrashkin, Y.; Salikhov, K. M.; Büchner, B.; Liu, F.; Rosenkranz, M.; Popov, A. A.; Kataev, V., Unusually large hyperfine structure of the electron spin levels in an endohedral dimetallofullerene and its spin coherent properties. Nanoscale
2020,
12, 20513-20521.
(Invited) Heteroatom Functionalization of N- and B-Doped Graphene
Authors: Arellano Luis M , Marrejón Myriam , Gómez-Escalonilla Romojaro Maria , Langa Fernando
Published: July 2021

One of the most important issues in the field of graphene for electronic and optoelectronic applications is how to modulate effectively the density of charge carriers, their mobility and their energy levels. One general strategy for achieving this goal is doping graphene with heteroatoms; in this approach, the properties of graphene are controlled by the nature of the dopant elements and by the percentage of doping. For example, by substituting carbon atoms with nitrogen or boron, it is possible to turn graphene into a semiconductor of n- or p-type, respectively. Both elements are by far the most common dopant elements and graphene doped with these heteroatoms have been widely used in electrocatalysis, as photocatalysts and as electronic materials.

Here, we will present our work in the N- and B- functionalization of N- and B-graphene and the influence of the nature of substituent on the electronic properties of the material.

References

M. Barrejón et al. Chem. Commun. 2015, 51, 16916

M. Barrejón et al. Chem. Sci. 2018, 9, 8221

H. Gobeze et al. Nanoscale Adv. 2019, 1, 4009

L.M. Arellano et al. Chem. Commun.
2019, 55, 9999

Figure 1
(Nanocarbons Division Robert C. Haddon Research Award) Chemical Functionalization of Synthetic Carbon Allotropes
Authors: Hirsch Andreas
Published: July 2021

Chemical functionalization of new C-allotropes is of fundamental interest and opens the door to unprecedented materials applications. In principle, the physical and chemical properties of fullerenes, carbon nanotubes (CNTs) and graphene are related to each other, although their levels of development vary considerably. In order to efficiently explore the reactivity of the less developed CNTs and especially that of graphene it is our goal to provide a unifying approach for the chemistry of all three new carbon allotropes. The fullerenes present the first family of synthetic carbon allotropes. Since their availability in macroscopic quantities numerous investigations with respect to their physical characterization and chemical functionalization have been carried out. CNTs - the second new family of C-allotropes - exhibit at least the same potential for unprecedented applications. Their chemistry, however, is much less developed. Although many protocols for covalent and non-covalent CNT functionalization have been published there are still many fundamental problems to be solved. This includes inter alia the highly selective functionalization of metallic- or semiconducting SWNTs, the high throughput isolation of SWNTs with single helicity, the development of general concepts allowing for tunable doping of individualized tubes with single helicity or least defined transport characteristics (metallic – semiconductive). Finally, the youngest representative in the list of new C-allotropes is graphene and its chemical functionalization opens exciting opportunities towards the development of precisely structured high performance materials. We will talk on the systematic investigation of the chemical properties of graphene both in homogenous solution and deposited on solid substrates. We have revealed fundamental reactivity principles, such as role of defects, charging and substrate. Moreover, we have disclosed for the first time basic fundamental topicity concepts. This allows us to tailor highly integrated graphene based 2D-materials. An example is the introduction of reversible covalent 2D-structuring providing the basis for chemical data storage.
(Invited) The Role of Gd in the Dy2GdN@C80 single Molecule Magnet
Authors: Greber Thomas
Published: July 2021

Endohedral fullerenes are perfect nanolaboratories for the study of 4f electron magnetism. The substitution of a diamagnetic scandium atom in Dy2ScN@C80 with magnetically isotropic gadolinium decreases the stability of a given magnetization that is imposed by the Dy2 unit and demonstrates Gd to accelerate the reaching of thermal equilibrium. X-ray magnetic circular dichroism at the M4,5 edges of Gd and Dy shows that Gd also affects the magnetic ground state. The Gd magnetic moment follows the sum of the external and the dipolar magnetic field of the two Dy ions and compared to Dy2ScN@C80 a lower exchange barrier is found between the ferromagnetic and the antiferromagnetic Dy configuration. The Arrhenius equilibration barrier as obtained from superconducting quantum interference device magnetometry is more than one order of magnitude larger, though a much smaller prefactor imposes the faster equilibration in Dy2GdN@C80. This sheds light on the importance of angular momentum balance and symmetry in magnetic relaxation [1].

[1] Gadolinium as a single atom catalyst in a single molecule magnet, Aram Kostanyan, Christin Schlesier, Rasmus Westerstrom, Jan Dreiser, Fabian Fritz, Bernd Buchner, Alexey A. Popov, Cinthia Piamonteze, Thomas Greber, arXiv:2009.12259 September (2020).

The figure shows the Dy2GdN@C80 molecule where the two Dy 4f9 and the Gd 4f7 orbitals of the paramagnetic entities are shown in red. Note the orientation of the Jz=15/2 Dy 4f9 orbitals towards the N3- ligand. Picture by Ari P. Seitsonen.

Figure 1
(Invited) Distance Dependent Electron Transfer Kinetics in Axially Connected Silicon Phthalocyanine-Fullerene Conjugates
Authors: Sastre-Santos Angela
Published: July 2021

The effect of donor-acceptor distance in controlling the rate of electron transfer in axially linked silicon phthalocyanine – C60 dyads has been investigated. Herein we will presented the synthesis and photophysical properties of two C60-SiPc-C60 dyads, 1 and 2, varying in their donor-acceptor distance. In the case of C60-SiPc-C60
1 where the SiPc and C60 are separated by a phenyl spacer, faster electron transfer was observed with k
cs equal to 2.7 x 109 s-1 in benzonitrile. However, in the case of C60-SiPc-C60
2, where SiPc and C60 are separated by a biphenyl spacer, a slower electron transfer rate constant, k
cs equal to 9.1 x108 s-1 was recorded. The addition of an extra phenyl spacer in 2 increased the donor-acceptor distance by ~ 4.3 Å, and consequently, slowed down the electron transfer rate constant by a factor of ~3.7. The charge separated state lasted over 3 ns, monitoring time window of our femtosecond transient spectrometer. Complimentary nanosecond transient absorption studies revealed formation of 3SiPc* as the end product and suggested that the final lifetime of charge separated state to be in the 3-20 ns range. Energy level diagram established to comprehend these mechanistic details indicated that the comparatively high-energy SiPc
.+
-C60

.-
charge separated states (1.57 eV) to populate the low-lying 3SiPc* (1.26 eV) prior returning to the ground state. [1].

Acknowledgments

This work was supported by the Ministerio de Ciencia e Innovación of Spain and FEDER funds (Grants CTQ2017-87102-R and RED2018- 102471-T to ASS) and National Science Foundation (Grant No. 1401188 and 2000988 to FD).

References

L. Martín-Gomis, S. Seetharaman, D. Herrero, P. A. Karr, F. Fernández-Lázaro, F. D’Souza, and Á. Sastre-Santos, Chem Phys.
Chem.,
2020, 21, 2254-2262.

Figure 1
Reactivity of Li+@C60@C240 and Photoinduced Charge Shift in Li+ Doped Giant Nested Fullerenes
Authors: Solà Miquel , Luque-Urrutia Jesús Antonio , Stasyuk Anton , Stasyuk Olga , Poater Albert , Voityuk Alexander A.
Published: July 2021

Over the last years, carbon nano-onions (CNOs) have been in focus in material science research. Apart from its prospective use in solar cells, the number of potential applications of CNOs have grown in the last decades. Among them, we can mention their application in gas storage processes, solid lubrication, or heterogeneous catalysis, and also as electrode materials in capacitors, anode materials in lithium-ion batteries, catalyst support in fuel cells, or electro-optical devices. From the analysis of the polarizability of CNOs, it was concluded that CNOs behave as near perfect nanoscopic Faraday cages.[1] If CNOs behave as ideal Faraday cages, the reactivity of the C240 cage should be the same in Li+@C240 and Li+@C60@C240. In the first part of this work, we have analyzed the Diels-Alder reaction of cyclopentadiene to the free C240 cage and the C60@C240 CNO together with their Li+-doped counterparts using density functional theory (DFT). We find that in all cases the preferred cycloaddition is on bond [6,6] of type B of the C240 cage. From the comparison between the reactivity of Li+@C240 and Li+@C60@C240, we conclude that C60@C240 does not act as a perfect Faraday cage.[2] In the second part of this work, we perform a systematic study of excited state properties of six double-layered Li+ doped fullerenes of Ih

symmetry: [Li@C60@C240]+, [Li@C60@C540]+, [Li@C60@C960]+, [Li@C240@C540]+, [Li@C240@C960]+ and [Li@C540@C960]+. On the basis of TDDFT calculations, we show that the long-wave absorption by the Li+ doped species leads to charge transfer (CT) between the inner and the outer shells unlike their neutral double-layered precursors. The CT energy depends strongly on the size of the concentric fullerenes and it can easily be tuned by varying both the encapsulated metal ion and the size of the shells. Two types of low-lying excited states are identified (1) capacitor-like structures, as Li+@C60
-@C240
+, with alternating positive and negative charges, and (2) states, where the positive charge is delocalized over the outer shell, as in Li@C240@C540
+.[3]

References

[1] R. R. Zope, J. Phys. B: At. Mol. Opt. Phys. 41 (2008) 41, 085101; [b] R. R. Zope, S. Bhusal, L. Basurto, T. Baruah and K. Jackson, J. Chem. Phys. 143 (2015) 084306.

[2] A. J. Luque-Urrutia, A. Poater and M. Solà. Chem. Eur. J., 26 (2020) 804-808.

[3] A. J. Stasyuk, O. A. Stasyuk, M. Solà and A. A. Voityuk. J. Phys. Chem. C 123 (2019) 16525-16532.

Figure 1
(Invited) Structural Studies of Open-Cage Fullerenes
Authors: Balch Alan , Pla-Quintana Anna , Castanyer Cristina , Gralinski Steven , Baldauf Lilia , Roy Mrittika
Published: July 2021

Open-cage fullerenes, fullerenes with orifices created by breaking some of the C-C bonds in a fullerene such as C60, are molecules that allow chemical access to both the external and the internal surfaces of the carbon cage. We have found such molecules to be challenging to crystallize and thereby fully structurally characterize through single crystal X-ray diffraction studies. We have also found that the reactivity of these open cage fullerenes can differ significantly from that of the parent fullerene (see A. Aghabali, S. Jun, M. M. Olmstead, A. L. Balch, Silver(I)-Mediated Modification, Dimerization, and Polymerization of an Open-Cage Fullerene. J. Am. Chem. Soc. 2016, 138, 16459-16465.) This talk will report recent studies of the crystallographically determined structures and reactivities of several open-cage fullerenes with particular attention given to the accessibility of the cage opening to chemical reactions.
(Invited) Negative Volume Compressibility in Sc3n@C80–Cubane Cocrystal with Charge Transfer
Authors: Bingbing LIU
Published: July 2021

According to the laws of thermodynamics, materials normally exhibit contraction or expansion along the directions of the applied pressure or tension. Here, we show that a man-made cocrystal of a metallofullerene and highly energetic cubane, with strained sp3 bonding, may exhibit an anomalous negative volume compressibility. In this cocrystal, the freely rotating fullerene Sc3N@C80 acts as a structural building block while static cubane molecules fill the lattice interstitial sites. Under high pressure, Sc3N@C80 keeps stable and preserves the crystalline framework of the materials, while the cubane undergoes a progressive configurational transformation above 6.5 GPa, probably promoted by charge transfer from fullerene to cubane. A further configurational change of the cubane into a low-density configuration at higher pressure results in an anomalous pressure-driven lattice expansion of the cocrystal (∼1.8% volume expansion). Such unusual negative compressibility has previously only been predicted by theory and suggested to appear in mechanical metamaterials.
(Invited) The Quantum Phase Interference in the Excited Triplet of Fullerene
Authors: Jiang Shang-Da
Published: July 2021

High spin magnetic molecules are promising candidates for quantum information processing because their intrinsic multiplicity facilitates information storage and computational operations. However, due to the absence of suitable sublevel splittings, their susceptibility to environmental disturbances and limitation from the selection rule, the arbitrary control of the quantum state of a molecular electron multiplet has not been realized. Here we exploit the photoexcited triplet of C70 as a molecular electron spin qutrit with pulsed electron paramagnetic resonance. We prepared the system into 3-level superposition states characteristic of a qutrit and validated them by the tomography of their density matrices. To further elucidate the coherence of the operation and the nature of the system as a qutrit, we demonstrated the quantum phase interference in the superposition. The interference pattern is further interpreted as a map of possible evolution paths in the space of phase factors, representing the quantum nature of the 3-level system.

Figure 1