bluuebunny/crossref_metadata_2025_split huggingface dataset:
(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) 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
(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) Magnetism and Electrochemistry of Fullerene-Based Composites
Authors: Feng Yongqiang , Wang Xiao , Dong Peipei 
Published: July 2021

Endohedral metallofullerenes (EMFs), a negatively sp
2-hybridized spherical carbon surface containing alternating hexagons and pentagons doped with metal ion(s) or cluster inside, have attracted more and more interests owing to their unique nesting structures and alluring chemical/physical properties. Herein, we will discuss several typical spin-active endohedral metallofullerenes. To steer the electron spin of paramagnetic fullerene molecules, a solid-state spin system was constructed via encapsulating paramagnetic fullerenes into the pores of metal-organic frameworks (MOFs) forming a EMF/MOF compostie, and an axisymmetric paramagnetic property was found. This kind of solid spin system can be used as a probe for nanoscale nuclear magnetic resonance or for motion imaging of a single biomolecule.
Besides, as a representative allotrope of carbon, fullerene-based composite also exhibit fascinating electrochemistry, e.g., serving as electrocatalyst. In this work, a novel hybrid electrocatalyst comprising fullerene carbon dot (FQD)-decorated cobalt nickel layered double hydroxide (CoNi-LDH) nanosheets anchored on porous nickel foam (NF) is elaborately fabricated. The obtained FQD/CoNi-LDH/NF exhibits superior electrocatalytic activity for hydrogen and oxygen evolution as well as urea oxidation under ambient atmosphere. Both experiment and density functional theory (DFT) calculations demonstrate that the charge transfer from FQD to CoNi-LDH could account for the excellent catalytic performance of the newly-synthesized catalyst, and the decorated FQD finely modulates the electronic structure of CoNi-LDH, favoring the adsorption of active hydrogen atom, and thus promote the catalytic process. The present work would provide useful guidance for designing and developing fullerene-based electrocatalysts for hydrogen production.
(Nanocarbons Division Best Poster Award - 3rd Place) Intrinsic Shear Strain in Graphene Heterostructures Detected Via Raman Spectroscopy
Authors: Schmidt Kirby , Li Xinyi , Pourianejad Sajedeh , Trofe Anthony , Rotkin Slava V. , Ignatova Tetyana 
Published: July 2021

Graphene’s electronic band structure is extremely sensitive to small perturbations in its crystal lattice. Because of this it is vital to correctly characterize strain, doping and defects in graphene through nondestructive measurements. Characterization through Raman Spectroscopy allows this nondestructive measurement. Graphene on Transition Metal Dichalcogenides (TMDCs) show increased shear strain which is not caused by defects introduced through the transfer method. We prove this using Raman analysis of graphene samples on silicon oxide and TMDC. Graphene shows G peak splitting and shift indicative strain increasing on top of TMDC when compared to nearby graphene on silicon oxide.
Acknowledgement: Authors acknowledge the JSNN, a member of the Southeastern Nanotechnology Infrastructure Corridor (SENIC) and National Nanotechnology Coordinated Infrastructure (NNCI), supported by the NSF (ECCS-1542174), The PSU Two-Dimensional Crystal Consortium – Materials Innovation Platform 2DCC-MIP, supported by NSF cooperative agreement (DMR- 1539916). Authors are grateful to Dr. S. Aravamudhan (JSNN) and Dr. J. Redwing (2DCC MIP).
(Invited) Two-Dimensional Pnictogens: Van Der Waals Growth, Stability, and Phase Transformation
Authors: Moutanabbir Oussama , Fortin-Deschênes Matthieu 
Published: July 2021

Pnictogens (P, As, Sb, Bi) emerged as a new class of elemental 2D materials displaying a wide range of electronic and topological properties. With their ns2 np3 valence electronic configuration and sp3 hybridization, group VA elements are the only elemental group which forms vdW and quasi-vdW structures throughout the entire group, thus providing a rich allotropic system. Light group VA elements crystallize in the semiconducting orthorhombic layered phase (A17) and heavier group VA elements prefer the semi-metallic rhombohedral layered phase (A7). At nanoscale thicknesses, group VA materials undergo various electronic phase transitions. For instance, A17 P – black phosphorus – is a high mobility 2D semiconductor with a thickness-dependent direct band gap gradually varying between 0.3-2 eV as its thickness decreases from bulk to single layer. Similarly, A7 Sb is predicted to exhibit topological semimetal, topological insulator, quantum spin Hall and indirect band gap semiconductor phases at thicknesses between 1 and 22 layers.
Despite their highly attractive scientific and technological potential, 2D materials remain scarcely implemented in scalable devices and technologies due to several challenges including among others the lack of large-area and uniform synthesis methods. In fact, many 2D materials exist only in the realm of theoretical predictions and most 2D materials can only be produced by mechanical or chemical exfoliation from bulk crystals, yielding 2D flakes with limited dimensions and poor thickness control. Developing epitaxial growth methods is therefore a crucial step to enable the integration of 2D materials in emerging technologies. With this perspective, this presentation will address the development of the molecular beam epitaxy (MBE) growth of group VA 2D materials on semiconducting and vdW substrates. Furthermore, thermal, ambient and phase stability of these emerging 2D materials is studied using in situ low-energy electron microscopy, transmission electron microscopy, x-ray photoelectron emission microscopy, and ab initio calculations. MBE growth of 2D-Sb and 2D-AsSb is demonstrated on Ge(111) and graphene. Real-time LEEM measurements of the growth dynamics combined with in situ STM allow to determine the nucleation and growth mechanisms on semiconductor and vdW substrates. Subtle behavior during growth or thermal annealing was revealed based on these in situ studies including the metastability and layered-to-layered phase transformation mechanisms of A17 2D-Sb, which was previously considered as an unstable Sb phase. These results provide a deeper understanding of vdW growth of group VA 2D materials and layered-to-layered phase transformation mechanisms.
Impedance Characteristics of Biofilms Formed on Graphene Films and Their Substrates
Authors: Kanematsu Hideyuki , Nakagawa Ryoichi , Torisawa Yuki , Miura Hidekazu , Ishihara Masatou , Ban Masahito , Hirai Nobumitsu , Kogo Takeshi , Barry Dana M. 
Published: July 2021

Biofilms are inhomogeneous film-like matters formed on materials by bacterial activities. They bring about many detrimental problems in various fields such as cooling pipes, kitchens, toilets, baths, marine structures, food industries, medical applications, hospitals etc., as well as beneficial purposes. Therefore, they should be controlled properly and the sensing is very important therefore. We have confirmed so far that graphene as one of representative 2D materials has high sensitivity to biofilm formation due to their pi electron clouds. The characteristics would lead to the application of biofilm sensors. In this experiment, we formed one layer, two layers and multi-layers graphenes were formed by a thermal CVD process on copper substrates and in some cases, they were moved to the surfaces of polyethylene and biofilms were formed on graphene films with those substrates. Then the impedance characteristics were measured and the relation between the impedance characteristics and biofilms formation/growth behaviors were investigated and discussed. As a result, we obtained the following results.
1. In the case of graphene films on all substrates, the characteristic peaks of impedance were observed at some specific frequencies.
2. The impedance peaks were different between copper substrates and PE ones.
3. The impedance peaks were also different according to the numbers of graphene layers.
4. The impedance peaks became more remarkable for non-freeze hydrated specimens.
5. In the case of polymeric substrates, the impedance characteristics of biofilms showed different patters.
We presume that the impedance peaks were obtained, since external polymeric substances (EPS) in biofilms would have absorbed electromagnetic waves. Therefore, the polymeric substrates could have affected the absorbance behaviors of electromagnetic waves differently. The application possibilities of the experimental results to biofilm sensors were finally discussed.
Nanoscale Patterning of Graphene Field-Effect Transistors for Single-Molecule Functionalization and Time Series
Authors: Bencherif Amira , Tie Monique , Martel Richard , Bouilly Delphine 
Published: July 2021

With the discovery of low-dimensional materials, the extreme miniaturization of field-effect transistors (FETs) has revealed such devices as powerful sensors for experiments at the single-molecule scale. In particular, FET devices functionalized with an individual molecule have been able to record, via fluctuations in the electrical conductance, various types of single-molecule dynamic changes, for example enzymatic activity1 DNA hybridization2,3 or DNA folding4. So far, such studies have mostly been carried out with FETs based on 1D materials such as carbon nanotubes (CNTs) or silicon nanowires (SiNWs). The 1D geometry of these materials facilitates the capture of a 0D molecule and provides enhanced sensitivity of the conductance to the functionalized site. However, FETs based on 1D materials often present scalability issues, due to challenges in controlling their growth and/or assembly.
Here, we propose an approach based on nanoscale patterning of a 2D material to assemble FET arrays compatible for single-molecule capture and detection. First, we report wafer-scale microfabrication of arrays of graphene field-effect transistors (GFETs) with micron-scale channels. Like its 1D counterpart, graphene presents a high and sensitive electrical conductivity as well as carbon-based surface chemistry for single-molecule functionalization. GFET arrays were built from high-quality graphene synthesized by chemical vapor deposition (CVD) and transferred using a custom automated process on patterned electrodes. Then, we describe the nanoscale patterning of graphene channels in nanoconstrictions suitable for single-molecule functionalization and sensitivity. Using electron-beam lithography (EBL) and deep reactive ion etching (DRIE), we were able to produce a combination of high-resolution features in graphene (<100nm) as well as nanofluidics reactions chambers (<50nm), to promote single-molecule chemistry on the graphene. We will present our recent results in functionalizing these nanoconstrictions with single-stranded DNA and in collecting high-resolution electrical time series from these constructs. Finally, we will discuss the performance of such graphene-based devices for single-molecule experiments.

Bibliography

Choi, Y., Weiss, G. A. & Collins, P. G. Single molecule recordings of lysozyme activity. Physical Chemistry Chemical Physics (2013). doi:10.1039/c3cp51356d

Sorgenfrei, S. & Shepard, K. L. Label-free field-effect-based single-molecule detection of DNA hybridization kinetics. Nat. Nanotechnol.
6, 126–132 (2011).

Vernick, S. et al. Electrostatic melting in a single-molecule field-effect transistor with applications in genomic identification. Nat. Commun.
8, 1–9 (2017).

Bouilly, D. et al. Single-molecule reaction chemistry in patterned nanowells. Nano Lett.
16, 4679–4685 (2016).
(Invited) Tuning Interlayer Exciton Energetics in Twisted and Stacked Materials
Authors: Graham Matt 
Published: July 2021

Using time-space resolved ultrafast microscopy on individual 2D crystal grains, we show how long-range interlayer electronic coupling can be selectively enhanced either by applying an E-field or by twisting the layer stacking orientation. In both cases, transient interlayer exciton states form and drive the optoelectronic material response. Considering first twisted bilayer graphene (tBLG), we discovered how stacking-angle tunable absorption resonances form a strongly-bound exciton state as a consequence of the symmetrized rehybridization of the interlayer 2p orbitals.[1] Using two-photon photoluminescence and intraband-transient absorption microscopies, we have recently imaged the photoemission and exciton dynamics from single-grains of tBLG. After resonant excitation, our results suggest the formation of strongly-bound (up to 690 meV), metastable interlayer exciton states. Our observation of resonant PL emission from twisted bilayer graphene materials in Fig. 1a is best explained by the theoretically predicted coexistence of strongly-bound interlayer excitons and metallic graphene continuum states. We show how stacking angle -tunable interlayer excitons states may permit new photocurrent extraction routes from quasi-stable interlayer excitons.
Unlike stacked graphene, semiconducting 2D transition metal dichalcogenides (TMDCs) have diffuse interlayer d-orbital overlap. To enhance interlayer electronic coupling in TMDCs, we apply an interlayer directed E-field, inducing electron-hole dissociation [2]. Time-resolved photocurrents show that stacked WSe2 devices can have both IQE >50% and fast (<60 ps) picosecond electron escape times. Our ultrafast photocurrent rates kinetics give the same E-field-dependent electronic escape and dissociation rates seen from optical ultrafast microscopy. To confirm the fast electronic escape rates, we show the ratio of the electronic rates accurately matches our overall WSe2 device IQE in the limit of zero Auger recombination. Collectively, we show how optical and photocurrent-based ultrafast microscopies together provide an analytical extraction of the photocurrent-generating ultrafast dynamics in both TMDCs and tBLG van der Waals stacked materials.

References

[1] H. Patel, L. Huang, C.J. Kim, J. Park, M. W. Graham, Stacking Angle-Tunable Photoluminescence from Interlayer Exciton States in Twisted Bilayer Graphene, Nature Comm, 10, 1445 (2019).
[2] K. T. Vogt, S.-F. Shi, F. Wang, M. W. Graham, Ultrafast photocurrent and absorption microscopy of few-layer TMD devices isolate rate-limiting dynamics driving fast and efficient photoresponse, J Phys Chem C, 124, 28, 15195–15204 (2020)

Figure 1