bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral Microscopy Resolves Carbon Nanotube Chromatic Diversity in Living Systems
Authors: Roxbury Daniel , Jena Prakrit Vaibhav , Williams Ryan , Heller Daniel
Published: February 2020

The intrinsic photoluminescence (fluorescence) of carbon nanotubes exhibits unique photostability, narrow bandwidth, near-infrared penetration of biological media, and environmental sensitivity. Advanced biological applications will require the spectral and spatial resolution of individual (n,m) nanotube species’ fluorescence and its modulation within live cells and tissues. We present an imaging approach to resolve nanotubes with single molecule resolution in live mammalian cells, in murine tissues ex vivo, and in live zebrafish endothelium. We used this method to identify chirality-resolved optical properties of single nanotubes in tissues and to precisely quantify fluorescent nanotubes in live cells.
An Easy Stereo-Specific and Regio-Selective Reaction for the Synthesis of Ester-[70]-Fullerene Derivatives
Authors: Castro Edison , Echegoyen Luis
Published: February 2020

Medicinal chemistry is one of the many fields where fullerene derivatives have been shown to be active and useful.[1,2] Wudl and coworkers reported the interactions of [60]-fullerene derivatives with the active site of HIV protease, driven by the lipophilicity of the carbon cage.[3] Unfortunately, fullerene derivative applications in this field are hindered mainly by their low water-solubility. To date, water-soluble fullerene C70 derivatives have not been extensively investigated. The lack of low symmetry of the C70 cage makes its selective functionalization more challenging than for C60. Therefore, just a few C70 water-soluble derivatives have been reported. [4,5] Here we report an efficient stereo-specific and regio-selective reaction for the synthesis of ester-pyrrolidinofullerene derivatives. These compounds are good precursors for the synthesis of their corresponding water-soluble carboxylic acid-pyrrolidinofullerenes.   

Figure 1. Stereo-specific and regio-selective 1,3-dipolar cyclo-addition reaction of ester-[70]-fullerene derivatives.

 

 

A. Jensen, S. Wilson, D. Schuster, Bioorg. Med. Chem. 1996, 4, 767.

T. Da Ros, M. Prato, Chem.
Commun. 1999, 663.

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1993, 115, 6506-6509.

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A. Kornev, A. Peregudov, V. Martynenko, J. Balzarini, B. Hoorelbekec, P. Troshin, Chem. Commun.
2011, 47, 8298–8300.

Figure 1
Boron-Doped Reduced Graphene Oxide (B-RGO) and Its Application to L-Cysteine Sensing
Authors: Chen I-Ting , Lu Hsin-Che , Chang Ting-Hsiang , Huang Li-De , Ho Kuo-Chuan
Published: February 2020

In this study, we prepare a boron-doped reduced graphene oxide thin film on the screen printed carbon electrode (SPCE) for the electrochemical sensing of L-cysteine (L-cys). L-cysteine, a sulfur containing amino acid, plays a crucial role in regulating the biological activity of certain proteins, peptides and enzymes. Low level of L-cys is related to myriad of diseases, including slow growth in children, depigmentation of hair, lethargy, liver damage, loss of muscle and fat, skin lesions, and weakness.[1]  However, current L-cys sensing techniques require intensive pretreatments[2
,
3]as well as purifications. As a result, developing a relatively easy, selective and sensitive L-cys biosensor in physiological study and clinical diagnosis is highly demanded.

In the electron energy loss spectroscopy (Fig. 1 (a)), the peaks of π*(~190 eV) and σ*(~200 eV) anti-bonding orbitals on the K-edge of boron (B) revealed the hybridized sp2-bonded B atoms in the graphene nanosheet. These two peaks indicates that the substitution doping is the dominate type of doping. The STEM-EELS mapping of B-RGO (Fig. 1 (b)) confirms that dopant B (green) is uniformly distributed on the reduced graphene oxide.

Electrochemical characterization shows different performances among bare SPCE, RGO/SPCE and B-RGO/SPCE in Fig. 1(c). The results show that with the help of boron, B-RGO (B=9.6%) possesses good electrocatalytic ability to L-cys by decreasing the overpotential and increasing the current density of the irreversible oxidation reaction. Fig. 1(d) shows a plot of the current density of the B-RGO/SPCE as a function time at various L-cys concentrations. The current density increases linearly with the increased L-cys concentration, as shown in the inset. The sensitivity of the B-RGO/SPCE is 20.7 mAcm−2M−1. The limit of detection (LOD), based on a signal-to-noise ratio of 3, for the B-RGO/SPCE is 0.07 μM.  

[1] S. Shahrokhian, Anal. Chem. 73 (2001), 5972

[2] G. Chwatko, E. Bald, Talanta,52 (2000) 509.

[3] K. Arlt, S. Brandt, J. Kehr, Journal of Chromatography A, 926 (2001) 319.

Figure 1
Bioconjugated Iron-Filled Carbon Nanotubes As Cancer Theranostics Agents
Authors: Pineux Florent
Published: February 2020

Magnetic nanoparticles (MNPs) and carbon nanotubes (CNTs) have emerged as two new classes of nanomaterials for simultaneous diagnostics and treatment (theranostics) of cancer. On one hand, MNPs can act as magnetic resonance imaging (MRI) contrast agents, magnetically-driven drug delivery cargoes, filtrations and selective separations of biological entities agents and magnetic fluid hyperthermia (MFH) treatments.[1] On the other hand, CNTs have been used against cancer as intracellular carriers for biologically relevant species[2] thanks to their large surface area and their faculty to penetrate cells or as infrared hyperthermia agents[3], among other possibilities.[4]

In order to combine the advantages of both parts, we synthesized in our group a hybrid composed of metallic iron nanoparticles filled in multiwall carbon nanotubes (Fe@CNTs) bioconjugated to the monoclonal antibody (mAb) Cetuximab. CNTs graphitic layers offers a protection against oxidation of iron nanoparticles, keeping them in more magnetically active phases whereas mAb targets epidermal growth factor receptor (EGFR) overexpressing A431 cancer cells. In a pilot study, we showed the in vitro efficiency of Fe@CNTs in selective targeting and elimination of A431 cells over control cell lines via magnetic filtration and hyperthermia.[5] We then studied in detail various Fe@CNTs possessing different phases of iron, in order to correlate their structural and magnetic properties onto their biological performances.[6]

In parallel we developed seminal work[7]led by our team about H-bonded supramolecular polymer (SMP) able to wrap around CNTs to exploit the potential of our Fe@CNTs as a non-covalent scaffold. We thus synthesized new pegylated H-bonded supramolecular polymers able to solubilize Fe@CNTs in aqueous media. Moreover, this polymer-CNTs nano-assembly shows interesting properties of reversible wrapping and un-wrapping under thermal stimulus, and is envisaged to be used for simultaneous MFH and triggered drug delivery treatments.

References:

[1]       V. I. Shubayev, T. R. Pisanic, S. Jin, Adv. Drug Deliv. Rev.

2009
, 61, 467–77.

[2]       H. Dai, Acc. Chem. Res.

2002
, 35, 1035–44.

[3]       R. Singh, S. V Torti, Adv. Drug Deliv. Rev.

2013
, 1–16.

[4]       C. Fabbro, H. Ali-Boucetta, T. Da Ros, K. Kostarelos, A. Bianco, M. Prato, Chem. Commun.

2012
, 48, 3911–26.

[5]       R. Marega, F. De Leo, F. Pineux, J. Sgrignani, A. Magistrato, A. D. Naik, Y. Garcia, L. Flamant, C. Michiels, D. Bonifazi, Adv. Funct. Mater.

2013
, 23, 3173–3184.

[6]       F. Pineux, M. Riccardo, A. Stopin, A. La Torre, Y. Garcia, C. Michiels, D. Bonifazi, Manuscript in preparation

[7]       A. Llanes-Pallas, K. Yoosaf, H. Traboulsi, J. Mohanraj, T. Seldrum, J. Dumont, A. Minoia, R. Lazzaroni, N. Armaroli, D. Bonifazi, J. Am. Chem. Soc.

2011
, 133, 15412–24.

Figure : Scheme of an iron-filled Carbon Nanotube conjugated with a monoclonal antibody (Fe@CNT-mAb), wrapped with our supramolecular polymer.

Figure 1
(Invited) Scan-Probe Microwave Reflectance of Horizontally Aligned Arrays of Single-Walled Carbon Nanotubes: Nanoscale Imaging of SWNT Electrical Properties in the Quantum Regime
Authors: Wilson William L. , Seabron Eric , Maclaren Scott , Xie Xu , Rotkin Slava V. , Rogers John A.
Published: February 2020

Single walled carbon nanotubes (
SWNTs
) are 1-dimensional nanomaterials with unique electronic properties that make them excellent candidates for next generation device technologies. While nanotube growth and processing methods have progressed steadily, significant opportunities remain in advanced methods for their characterization, inspection, and metrology. We explore the application of nanoscale microwave reflectivity to study
SWNT
electronic properties. Using Microwave Impedance Microscopy (MIM) and newly developed Microwave Impedance Modulation Microscopy (MIM2
), we image horizontal SWNT arrays showing the imaginary part of the reflectivity from nanotubes is dominated by quantum capacitance, a direct probe of SWNT electronic behavior. Microwave imaging offers an extremely versatile "nondestructive" tool for characterization. We reveal the direct correlation of the free carrier density via MIM, the DOS dispersion via MIM2
, with the nanotube’s structural morphology measured simultaneously via AFM. These techniques offer a new window into CNT physics and could have tremendous impact, enabling optimization of enriched growth processes and post-growth purification, and aiding analysis of device-contact interactions.
(Invited) Single Carbon-Nanotube Photonics and Optoelectronics
Authors: Kato Yuichiro K.
Published: February 2020

Single-walled carbon nanotubes have unique optical properties as a result of their one-dimensional structure. Not only do they exhibit strong polarization for both absorption and emission, large exciton binding energies allow for room-temperature excitonic luminescence. Furthermore, their emission is in the telecom-wavelengths and they can be directly synthesized on silicon substrates, providing new opportunities for nanoscale photonics and optoelectronics.

Here we discuss the use of individual single-walled carbon nanotubes for generation, manipulation, and detection of light on a chip. Their emission can be efficiently coupled to specially-designed silicon photonic-crystal nanobeam cavities [1]. With the strong absorption polarization at the nanoscale, they allow for unconventional polarization conversion that results in giant circular dichroism [2]. More recently, we have found that alternating gate-voltages can generate optical pulse trains from individual nanotubes [3]. Ultimately, these results may be combined to achieve further control over photons at the nanoscale.

Work supported by KAKENHI, The Canon Foundation, The Asahi Glass Foundation, JSPS Open Partnership Joint Projects, and the Photon Frontier Network Program of MEXT, Japan.

[1] R. Miura, S. Imamura, R. Ohta, A. Ishii, X. Liu, T. Shimada, S. Iwamoto, Y. Arakawa, Y. K. Kato, Nature Commun. 5, 5580 (2014).

[2] A. Yokoyama, M. Yoshida, A. Ishii, Y. K. Kato, Phys. Rev. X 4, 011005 (2014).

[3] M. Jiang, Y. Kumamoto, A. Ishii, M. Yoshida, T. Shimada, Y. K. Kato, arXiv:1407.7086.
(Invited) Charge Separation and Recombination at Semiconducting Single-Walled Carbon Nanotube Interfaces
Authors: Blackburn Jeffrey L. , Dowgiallo Anne-Marie , Mistry Kevin , Ihly Rachelle , Ferguson Andrew , Kopidakis Nikos
Published: February 2020

The time scales and mechanisms for interfacial charge separation and recombination play crucial roles in determining efficiencies of excitonic photovoltaics. Semiconducting SWCNTs are robust light absorbers that have garnered increasing attention as the electron-donating or electron-accepting components in excitonic solar cells. In particular, near-infrared photons are harvested efficiently by semiconducting single-walled carbon nanotubes (SWCNTs) paired with appropriate electron acceptors, such as fullerenes (e.g. C60). While the reported AM1.5 power conversion efficiencies of such devices are steadily increasing, significant improvements remain to be made if a better fundamental understanding is reached for the kinetics and thermodynamics of exciton dissociation and charge recombination. In this presentation, I will discuss a number of time-resolved spectroscopic studies on donor:acceptor heterojunctions that incorporate semiconducting SWCNTs with widely varying band gaps and frontier orbital energies. Following the evolution of excitons and charges with multiple techniques provides a platform for understanding the time scales and quantum yields for interfacial charge transfer, recombination rates and mechanisms, and the dependence of charge transfer rates and yields on interfacial energetics.
Multi-Walled Carbon Nanotube Electrode Optimization for Thermocells
Authors: Holubowitch Nick , Lippert Cameron , Landon James , Liu Kunlei
Published: February 2020

There is an abundance of rejected thermal energy in industrial settings available for conversion to electricity by devices such as thermocells. Compared to solid state thermoelectric technology, thermocells scavenge low-grade heat more efficiently and offer 10-fold greater Seebeck coefficients (ferro/ferricyanide α = -1.4 mV/K). Since aqueous ferrocyanide cells are thermodynamically constrained by the Seebeck coefficient, focus has shifted to optimizing their kinetic performance.

Nanocarbons, particularly multi-walled carbon nanotubes (MWNTs) are emerging as the favored active electrode material in thermocells (1-3). These offer high conductivity and large electrochemically active surface areas. The preparation of MWNT-based electrodes, however, is no trivial task and non-electrochemically active binder materials (e.g. PVDF) are nearly always required. A variety of methods for MWNT/PVDF electrode casting have been investigated but doctor blade and spray-coat methods are currently lowest cost and most commonly employed. In this study, we contribute to the on-going optimization of spray-coated MWNT/PVDF on Al electrodes by exploring the influence of mass loading and active material-binder content via characterization in functioning full thermocells.

While varying the MWNT/PVDF ratio had little impact on peak power densities, we found that the thinnest possible coatings (i.e. one coat) yielded the highest power density per mass of MWNTs at 290 W kg-1. This suggests that tortuosity and/or poor wettability (hydrophobicity) of the MWNT electrodes limit the penetration depth of aqueous ferro/ferricyanide ions during thermoelectric conversion. Therefore, if coating thickness is strictly controlled, only 0.08 mg cm-2 (in our case) is needed. This minimizes inactive bulk MWNTs and brings the previously prohibitively expensive MWNTs to a fraction of the cost of the ferro/ferricyanide electrolyte for thermal to electric energy harvesting. The findings may be of broader interest for the fabrication of any electrochemical cells where integration of MWNTs is desired.

Figure 1. Potential-current and power curves of thermocells for three thicknesses of spray-coated MWNT/PVDF electrodes on Al. Current and power are normalized by MWNT mass, where the thicknesses refer to loadings of 1.0, 0.23, and 0.08 mg cm-2 MWNTs at 50/50 MWNT/PVDF content by mass.

References

1. R. Hu, et al., Nano Letters, 10(3), 838 (2010).

2. T.J. Kang, et al., Advanced Functional Materials, 22(3), 477 (2012).

3. P.F. Salazar, S. Kumar, and B.A. Cola, Journal of the Electrochemical Society, 159(5), B483 (2012).

Figure 1
(Invited) Etching of Surfactant from Solution-Processed, Type-Separated Carbon Nanotubes and Impact on Device Behavior
Authors: Léonard François
Published: February 2020

Semiconducting single-walled carbon nanotubes (SWCNTs) have great potential for use in electronic and optoelectronic devices.  However, methods for synthesizing SWCNTs produce a mixture of metallic and semiconducting materials requiring additional processing to separate by electronic type. Purification and enrichment of the semiconducting fraction is readily achieved using centrifugation of aqueous suspensions of SWCNTs with the help of surfactants, but this leaves residual surfactant on the SWCNT surface that can impact their electronic and optical properties. Here, we present a detailed study of the sodium taurodeoxycholate (STDC) surfactant removal process during vacuum annealing and show that it occurs through fractionation of the surfactant and that complete removal requires exceedingly high temperatures, indicating strong binding to the SWCNTs. We then present an approach based on air oxidation and mild annealing to completely remove the surfactant while maintaining the SWCNT properties. Using this approach, we compare single-SWCNT electronic devices with and without STDC and show that despite the very strong surfactant binding it does not affect device performance substantially.
(Invited) Carbon Nanotubes: From the Origin of Helicity to Application
Authors: Harutyunyan Avetik R
Published: February 2020

Despite recent advances in experimental studies on the preferential and helicity selective growths of carbon nanotubes the mechanism of helicity formation still remains elusive, which hinder further progresses in selective synthesis. Here we will present the results of the studies on nucleation of the carbon cap, believed to be responsible for the helicity of the surface catalyzed carbon nanotubes. We found that the cap formation involves graphene growth across various adjacent facets of catalyst particle and an explicit introduction of defects. As a result the graphene embryos incorporate in their hexagonic network various polygons to accommodate the curved 3D geometry that initiates carbon dome formation. Taking into account the census of nanotube cap and the fact that given cap fits only one nanotube wall we suggest that the carbon cap can serve as a precursor that sets the symmetry of growing tube.

Our recent progresses in production of carbon nanotubes, nanotube reinforced composites and their potential applications also will be presented.
Effects of Growth Substrates on Growth Mode of Carbon Nanofibers
Authors: Tian Meijuan , Zhang Qian , Zhang Cuixia , Dong Lifeng
Published: February 2020

Excellent properties of carbon nanofibers, such as high electrical conductivity, high specific strength, and low mass density, have attracted lots of research interest. The realization of the controllable synthesis of carbon nanofibers is the final purpose through studying the growth mechanism, which has a close relation to reaction conditions for carbon fiber synthesis.

In this study, we have synthesized vapor grown carbon nanofibers on three types of substrates: graphite, ceramic, and titanium dioxide nanotube array, which were coated with copper salt catalyst precursors. Copper salt and acetylene were used as catalyst precursor and carbon source, respectively. The morphology and structure of the as-obtained product were analyzed using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). Experimental results demonstrate that the morphology of carbon fibers synthesized on graphite substrate is similar to that on the ceramic. However, carbon fibers with small diameters of about 20-40 nm were synthesized on the titanium dioxide nanotube arrays. This means, growth substrate plays important roles in the formation of catalyst particles and thereby affects the growth mode of carbon nanofibers.
(Invited) Carbon Nanotube Separation By Aqueous Two-Phase Extraction: A Progress Report
Authors: Zheng Ming
Published: February 2020

In this talk, I will report recent progress made at NIST in carbon nanotube (CNT) separation by the aqueous two-phase (ATP) method. We have found that redox chemistry of carbon nanotubes can be used for band-gap dependent sorting of carbon nanotubes by ATP. The redox mechanism appears to be a general one controlling other types of CNT separations. We have also identified new DNA sequence patterns that have improved recognition for specific chirality CNTs, making ATP-based DNA-CNT separation much more efficient.
Spectroscopic Investigations into the Aqueous Two-Phase Partitioning of Carbon Nanotubes
Authors: Streit Jason K. , Gui Hui , Ao Geyou , Fagan Jeffrey A. , Hight Walker Angela R. , Zhou Chongwu , Zheng Ming
Published: February 2020

Aqueous two-phase extraction is a robust and cost-effective technique recently demonstrated to successfully separate both surfactant-coated and DNA-wrapped single-wall carbon nanotubes (SWCNTs) by diameter and electronic structure. In general, partitioning of the SWCNTs into the two different polymer phases can be modulated by the addition of different chemical species. We show that nanotube partitioning is additionally sensitive to redox chemistry, which can be tuned to sort surfactant dispersed SWCNTs by semiconducting bandgap and metallicity. Recent progress on high purity optical isomer separation of DNA-SWCNT hybrids will also be presented. Mechanistic insights are gained through spectroscopic studies.
(Invited) Aggregation State of Carbon Nanotubes in Solution
Authors: Okazaki Toshiya
Published: February 2020

Because of their superior mechanical, optical, thermal and electrical properties, carbon nanotubes (CNTs) have been paid particular attention since their discovery. Although much progress has been made so far, it is widely recognized that the bottleneck for applications is to prepare the homogeneous dispersion of CNTs. Indeed the functionality of a wide range of applications depends on the individual CNTs rather than the CNT bundles. The evaluation of dispersion states of CNTs in solutions has therefore been one of the serious issues in the CNT community. Here we examine the dispersion and the aggregation states of (CNTs) solution by the several characterization techniques such as a centrifuge sedimentation analysis. The estimated particle size and distribution will be discussed as compared to the physical properties of the composite materials.

 

This paper is based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO).
Swnt-Sorting with a Removable Solubilizer Based on Dynamic Supramolecular Coordination Chemistry
Authors: Nakashima Naotoshi , Toshimitsu Fumiyuki
Published: February 2020

Highly pure semiconducting single-walled carbon nanotubes (SWNTs) are essential for the next generation of electronic devices, such as field-effect transistors and photovoltaic applications, but contamination by metallic-SWNTs reduces the efficiency of their associated devices. Polyfluorene-based copolymers (PFOs)1, 2 have been intensively studied because they dissolve/extract only sem-SWNTs in toluene by a simple sonication method. We have previously demonstrated a rational method for the selective extraction of a specific chirality of the sem-(n,m) SWNTs using a series of systematically designed fluorene-based copolymers3-4. Moreover, we revealed that the PFO copolymers with a bulky optically active moiety could separate the right- and left-handed sem-SWNTs5. However, there are several serious problems when using PFOs; that is, difficulty in the removal of the wrapped PFOs from the SWNTs/PFO composites6, 7 as well as their low extraction efficiency from the as-produced SWNTs1,
2.

     Here we report a simple and efficient method for the separation of semiconducting- and metallic-SWNTs based on supramolecular complex chemistry.8 We describe the synthesis of metal-coordination polymers (CP-M) composed of a fluorene-bridged bisphenanthroline ligand and metal ions. Based on a difference in the ‘solubility product’ of CP-M-solubilized semiconducting-SWNTs and metallic-SWNTs, we readily separated semiconducting-SWNTs. Furthermore, the CP-M polymers on the SWNTs were simply removed by adding a protic acid and inducing depolymerization to the monomer components. We also carried out molecular mechanics calculations to reveal the difference of binding and wrapping mode between CP-M/semiconducting-SWNTs and CP-M/metallic-SWNTs.

     This study opens a new stage for the use of such highly pure semiconducting-SWNTs in many possible applications.

 

References

[1] Chen, F., Wang, B., Chen, Y., Li, L.-J. Nano Lett.
7, 3013–3017 (2007).

[2] Nish, A., Hwang, J., Doig, J., Nicholas, R. Nature Nanotech.
2, 640-646 (2007).

[3] Ozawa, H. et al.
J. Am. Chem. Soc.
133, 2651–2657 (2011).

[4] Ozawa, H., Ide, N., Fujigaya, T., Niidome, Y., Nakashima, N. Chem. Lett.
40, 239–241 (2011).

[5] Akazaki, K., Toshimitsu, F., Ozawa, H., Fujigaya, T., Nakashima, N. J. Am. Chem. Soc.
134, 12700–12707 (2012).

[6]  Izard, N. et al., App. Phys. Lett.
92, 243112 (2008).

[7] Jakubka, F. et al., ACS Macro Lett.
1, 815–819 (2012).

[8] Toshimitsu, F., Nakashima, N. Nature Comm.,
2014, 5, art no. 5041.
High-Fidelity Single-Column Selective Separation of Swcnts
Authors: Zhao Yang , Clar Justin , Xu Jia , Yuan Tianyu , Bonzongo Jean-Claude J , Ziegler Kirk J
Published: February 2020

Post-synthesis separation of single walled carbon nanotubes (SWCNTs) has been studied with great interest in the past decade. Among the most promising techniques, the selective adsorption of SWCNTs onto hydrogel stationary phases including both agarose and dextran provides opportunity for large-scale separations with relatively high purity. Recently, successful progresses have been achieved for further purification of semiconducting fractions separation into individual chiralities. However, severe limitations exist for large scale production including, minimal throughput, reproducibility, and hydrogel lifetime. Our previous work has highlighted the importance of surfactant structure along SWCNT sidewalls in the separation mechanism.  Using our understanding of the mechanism, we have begun collecting both mono-chiral and near mono-chiral s-SWCNT fractions in a single column using a co-surfactant elution profile at a single temperature. Additionally, we report the effect of common preprocessing steps on the overall separation quality. Finally, it is again demonstrated that effective methods of hydrogel regeneration are a much needed area of further study.
(Invited) Interfacial Functionalization of Carbon Nanotubes: From Effective Charge Propagation and Storage to Enhancement of Electrocatalytic and Bioelectrocatalytic Properties
Authors: Kulesza Pawel J
Published: February 2020

Of particular interest to the preparation of advanced materials is synthesis and characterization of carbon nanostructures (particularly nanotubes) or noble metal nanoparticles, their stabilization (e.g. through self-assembly), as well as organization into two-dimensional arrays and three-dimensional network films through controlled fabrication (e.g. sequential attraction). Thus functionalized nanosized materials with well-defined composition, structure and thickness can be formed. The interfaces can also be highly functionalized, and they can exhibit specific catalytic or unique electronic, charge storage, optical and sensing properties. We explore here the ability of inorganic structures to stabilize and derivatize carbon nanotubes. Among inorganic systems, polyoxometallates of molybdenum and tungsten are attractive since they can not only adsorb irreversibly on solid surfaces but also exhibit reversible stepwise multi-electron transfer reactions. The concept of the layer-by-layer formation of hybrid assemblies composed of anionic polyoxometallate-protected carbon nanotubes (or metal nanoparticles) and ultra-thin films of positively charged conducting polymers (e.g. PEDOT) or polycationic metal oxo species (e.g. zirconyl or vanadyl)  will be described and discussed here. The resulting novel composite materials have been fabricated as thin or moderately thick (µm level) films on electrode surfaces. As evidenced from STM and scanning electron microscopy, their morphology is still granular but the structure is fairly dense. Further, they are characterized by fast dynamics of charge propagation. Obviously, this research is of importance to the construction of effectively operating charge storage devices (capacitors), charge mediators (e.g. in bioelectrochemistry), molecular electronic systems and electrocatalysis. In the latter case, polyoxometallates can also be applied to stabilize and link Pt-Ru, Pt-Sn and various alloyed Pt-based nanoparticles. It is apparent from diagnostic cyclic voltammetric, rotating disk voltammetric  and chronoamperometric measurements that such systems exhibit attractive properties towards electroreduction of oxygen or carbon dioxide as well as oxidation of small organic molecules (ethanol, methanol or dimethyl ether). In addition to the fact that introduction of carbon nanotubes improves charge distribution at the electrocatalytic interface, further addition of metal oxide nanospecies can generate –OH groups at low potentials that induce oxidation of passivating CO adsorbates (e.g. on Pt); they can potentially break C-H or C-O bonds, as well as they can possibly weaken C-C bonds during ethanol oxidation (e.g. through changes of the electronic properties of Pt).
Observation of Efficient Upconversion Photoluminescence of Single-Walled Carbon Nanotubes
Authors: Miyauchi Yuhei , Matsuda Kazunari
Published: February 2020

Because of their potential applications in optoelectronics and bioimaging, photoluminescence (PL) properties of single-walled carbon nanotubes (SWNTs) have attracted much attention over the past decade [1-3]. Here, we report a novel aspect of the PL properties of SWNTs: availability of near-infrared PL (~950-1000 nm) by excitation with longer wavelength light (>1100-1200 nm), namely, upconversion PL. On the basis of the observations of temperature and excitation photon energy dependence, the observed phenomenon is attributed to the efficient phonon-assisted exciton upconversion processes. Furthermore, we demonstrate that strong enhancement of the upconversion PL occurs with additional chemical treatment on SWNTs. Materials exhibiting efficient upconversion PL in the near infrared range have been strongly desired for the observation of deep inside of highly scattering biological media. Our findings may thus open the door to the application of SWNTs in upconversion imaging of unprecedentedly deep inside of biological tissues.

[1] Y. Miyauchi, J. Mater. Chem. C 1, 6499 (2013). [2] Y. Miyauchi, M. Iwamura, S. Mouri, T. Kawazoe, M. Ohtsu, and K. Matsuda, Nature Photon. 7, 715 (2013). [3] M. Iwamura, N. Akizuki, Y. Miyauchi, S. Mouri, J. Shaver, Z. Gao, L. Cognet, B. Lounis and K. Matsuda, ACS Nano, asap (2014).
Advances in the Gel Chromatography Separation Processes with the Use of Duel-Surfactant and Surfactant-Salt Techniques
Authors: Capasse Ryan Charles , Zeghum Bilal , Rocha John-David R
Published: February 2020

Carbon nanotubes are considered a material of the future due to their wide applicability from microchips to sports gear. Single-walled carbon nanotubes (SWCNTs) can be separated into different species depending on their structure; metallic, or semiconducting. Here we will discuss the process of separating single-walled carbon nanotubes (SWCNTs) via gel-based chromatography. Novel innovations in the separation process have been made through the use of both dual-surfactant and surfactant-salt gradient processes. We outline the effect of surfactants such as SDS, SC, SDC, and AOT as well as different Alkaline Earth Metal cations. Through the use of these two methods individually, RNMSL has been able to isolate, with a high degree, metallic and semiconducting species. Furthermore, to confirm the extraction of different species of NTs, characterization was performed via absorbance and fluorescence spectroscopy.
Sensitization of Rare Earth Ions with Carbon Nanotube Plasmonic Antennas
Authors: Sofka Benjamin Joseph , Rotkin Slava V.
Published: February 2020

Complexes containing rare earth ions (REI) and single-walled carbon nanotubes (SWNT) functionalized with single stranded DNA show promise to be utilized for the optical sensing of bio-molecules [1]. However, the electromagnetic interactions between the SWNT and the REI have not been sufficiently studied. In this work, we focus on the plasmonic interaction between the SWNT and a REI such as Terbium or Europium for their use as a biosensing complex.

The SWNT may act as a plasmonic antenna and generate a local field in the vicinity of the REI. We use the transmission line model [2] to model the plasmonic properties of the SWNT antenna.  The incoming light induces a surface current distribution:

I(z)=(V0/Zc)sinh[γp(l/2-|z|)]

where V0 is the input voltage into the transmission line model determined by the applied electric field, Zc is the characteristic impedance of the SWNT which is approximately 12 kΩ, γp is the plasmon propogation constant, and l is the length of the tube which we take to be 1 μm.  We estimate a field enhancement factor of approximately 106in the near field given by:

F=ωl(LC/2)1/2/(k2r2)

where L is the kinetic inductance of the SWNT, C is the total capacitance including both electrostatic and quantum capacitances, r is the radial distance between the SWNT axis and the REI, and k and ω are the wavevector and frequency of the incoming light, respectively.

The electromagnetic fields will be calculated using the electric Hertz potential satisfying the Helmholtz equation with proper boundary conditions.  The conductivity of the SWNT antenna in the transmission line model is given by:

σ=iωL-1/(ω2+iωL-1R-C-1L-1 γp
2)

where R is the resistance of the SWNT.

The interaction of these calculated plasmonic fields with the REI will modulate the lifetimes of the REI. The modulated lifetimes of an electric dipole emitter will be calculated to model the allowed optical transitions of the particular REI.  To include the modulations of the optically dark REI transitions, a magnetic dipole emitter will be used.

To conclude, these results will give a better understanding of the near field electromagnetic interactions that take place in complexes containing SWNTs and REIs and allow for more efficient sensors.

Acknowledgement:  This work was supported by:  NSF ECCS-1202398

References:

[1] T. Ignatova, H.Najafov, A. Ryasnyanskiy, I. Biaggio, M. Zheng, and SV. Rotkin, “Significant FRET between SWNT/DNA and Rare Earth Ions: A Signature of Their Spatial Correlations”, ACS Nano 2011 5 (7), 6052-6059

[2] PJ. Burke, S. Li, Z.Yu, "Quantitative theory of nanowire and nanotube antenna performance," IEEE Transactions on  Nanotechnology  2006 5 (4), 314-334.
New Endohedral Fullerenes Containing Uranium
Authors: Echegoyen Luis , Buck David
Published: February 2020

In 1992, Smalley et al reported (Science
1992, 257, 1661) the mass spectral detection of a family of endohedral fullerene compounds containing uranium inside the carbon cages. These series included: U@C58, U@C60, U@C68, U2@C50, U@C70, U2@C52, U@C72, U2@C58, and U2@C60, but none of these compounds were isolated or otherwise characterized. In 2007, Lu et al reported theoretical calculations for U2@C60 and predicted that the encapsulated uranium dimer would exhibit a sextuple metal-metal bond. We have succeeded in producing, detecting and partially isolating a totally new family of endohedral uranium-containing fullerenes, including: U2C78, U2C79, U2C80 and U2C81, see attached figure for the corresponding MALDI. The synthesis, purification and partial characterization of these new endohedral compounds will be presented and discussed.

Figure 1
Endohedral Fullerenes Bis-Adducts: Regio-Chemistry Control Directed By the Cluster inside
Authors: Cerón Maira R. , Izquierdo Marta , Echegoyen Luis
Published: February 2020

Exohedral functionalization of endohedral fullerenes is essential to increase their solubility and explore their properties and potential applications in nanomaterial science.[i] At the present, few bis-derivatives have been reported, mainly because of the low yields and large number of isomeric products obtained.[ii] Dorn et al. and Akasaka et al. suggested than bis-adduct formation appears to be controlled by the metal or metallic cluster inside. Here we report the use of a well known method (tether-directed remote multifunctionalization)[iii] for the bis-functionalization of new endohedral fullerene bis-derivatives and compare the results to those observed for independent bis-pyrrolidine additions.

Figure 1. a)
Bis-adduct derivative of M3N@Ih
-C80 using the tether-directed remote multifunctionalization method (M = Lu, Sc). b)
Bis-pyrrolidine derivative of M3N@Ih
-C80 using two independent additions (M = Lu, Sc).

[i](a) M. N. Chaur, F. Melin, A. L. Ortiz, L. Echegoyen, M. N. Chaur, F. Melin, A. L. Ortiz, L. Echegoyen, Angew. Chem. Int. Ed.
2009, 48, 7514-7538 (b) D. M. Rivera-Nazario, J. R. Pinzón, S. Stevenson, L. A. Echegoyen, J. Phys. Org. Chem.
2013, 26, 194-205 (c) M. R. Cerón, F.-F. Li, L. Echegoyen, J. Phys. Org. Chem.
2014, 27, 258-264.

[ii](a) S. Stevenson, R. R. Stephen, T. M. Amos, V. R. Cadorette, J. E. Reid, J. P. Phillips, J. Am. Chem. Soc.
2005, 127, 12776-12777 (b) T. Cai, L. Xu, C. Shu, H. A. Champion, J. E. Reid, C. Anklin, M. R. Anderson, H. W. Gibson, H. C. Dorn, J. Am. Chem. Soc.
2008, 130, 2136-2137 (c) M. O. Ishitsuka, S. Sano, H. Enoki, S. Sato, H. Nikawa, T. Tsuchiya, Z. Slanina, N. Mizorogi, M. T. H. Liu, T. Akasaka, S. Nagase, J. Am. Chem. Soc.
2011, 133, 7128-7134.

[iii]C. Thilgen, F. Diederich, Chem. Rev. 
2006, 106, 5049-5135.

Figure 1
Electrochemical Activation of the Least Reactive Endohedral Fullerene: Sc3N@I
h-C80
Authors: Rivera-Nazario Danisha Marie , Izquierdo Marta , Filippone Salvatore , Martin Nazario , Echegoyen Luis
Published: February 2020

The low reactivity of endohedral fullerenes compared with empty fullerenes makes their functionalization and further applications very challenging. To overcome their low reactivity, part of our research is focused on exploring alternative synthetic pathways for their functionalization. Some examples include the exohedral functionalization through photochemical reactions and electrosynthesis. Electrochemical methods in particular provide control over the state of oxidation/reduction of the endohedral compounds. Extensive research has been done with anionic empty fullerenes species but until recently, only some anionic endohedral fullerenes used as nucleophilic reagents have been explored. However, cationic radical species of endohedral compounds as electrophilic reagents for exohedral functionalizations have never been reported. Furthermore, regioselective and enantioselective addition reactions are also not well studied. Using electrochemical methods of endohedral fullerenes we can tune the HOMO-LUMO energy levels of the species in play to perform reactions that are unsuccessful by other methods. Herein, we report the first asymmetric 1,3-dipolar cycloaddition using the cation radical of Sc3N@I
h-C80 through both electrochemical and chemical pathways using controlled potential electrolysis and chemical oxidation, respectively.
Unprecedented Chemical Reactivities and Potential Utilities of Paramagnetic Endohedral Metallofullerenes
Authors: Takano Yuta , Akasaka Takeshi
Published: February 2020

The inside metals of endohedral metallofullerenes (EMFs) lead remarkable features, such as unique molecular structures, and magnetic and electronic properties.[1] Among EMFs, paramagnetic EMFs are of particular interest because interplay between π-electron spins on the fullerene cage and inside metal atoms is expected to produce unconventional magnetic features.

   Unique properties of paramagnetic EMFs may lead to unique chemical reactivities. In this regard, despite the former efforts, much work is still needed for a better control on the chemical reactivity of the increasing variety of EMFs. For an easier accessibility to EMFs based materials, a wider availability of chemical functionalization methods on EMFs is required.

   Meanwhile, La@C82 has extensively been investigated as a prototype paramagnetic fullerene because it is the first EMF which was reported the successful isolation for the first time.[2] Moreover, it was demonstrated that a family of lanthanum containing fullerenes were produced and that extraction with toluene yielded abundantly La@C82. La@C82 has an electronic structure which is best described as [La]3+[C82]3- with an open-shell electronic character that is a consequence of transferring three electrons from lanthanum to C82(Scheme). The resulting electron spin imposes unique chemical reactivity, radical character, and magnetic properties.

   In this talk, I will present remarkable chemical reactivities and molecular properties of paramagnetic EMFs; La@C
2v
-C82,[3] La@Cs
-C82
[4] and Ce@C
2v
-C82.[5] Their unique characteristics cannot be expected in ordinary chemical compounds and empty fullerenes, and are promising for creating novel electronic and magnetic materials with utilizing their unprecedented electronic properties.

References:

[1] (For reviews of EMFs) (a) Chemistry of Nanocarbons; Akasaka, T., Wudl, F., Nagase, S., Eds.; Wiley: Chichester, 2010. (b) Popov, A. A. et al. Chem. Rev.
2013, 113, 5989.

[2] Chai, Y. et al.
J. Phys. Chem.
1991, 95, 75648.

[3] (a) Takano, Y. et al. J. Am. Chem. Soc. 2008, 130, 16224. (b) Takano, Y. et al. Chem. Commun. 2010, 46, 8035.

[4] Takano, Y. et al. J. Am. Chem. Soc. in press. DOI: 10.1021/ja509407j

[5] Takano, Y.et al. J. Am. Chem. Soc.
2009, 131, 9340.

Figure 1
Structural Studies of Endohedral Fullerenes
Authors: Balch Alan L. , Olmstead Marilyn M. , Ghiassi Kamran , Wang Guan-Wu
Published: February 2020

Recent results from single crystal X-ray diffraction studies of endohedral fullerenes will be presented.  Attention will be focuse on examples of cocrystallization and their utility in determineation of endohedral structure and the nature of the interactions within cocrystals.  Additional results on functionalized endoehdrals will be presented to show some unprecedented transformations of the addends.
Spin-Preserving N@C60 Cyclopropane Addition: Revisiting N@C60 Reactivity and Stability
Authors: Porfyrakis Kyriakos
Published: February 2020

The paramagnetic molecule N@C60 is a rare example of endohedral fullerene where the encapsulated nitrogen atom is almost completely isolated from the fullerene cage. This results in very long electron spin phase coherence times. Nitrogen is a very reactive element and indeed the N@C60 molecule is a fragile entity that has to be carefully protected from heat and light. On the other hand, functionalization of N@C60 can be achieved via chemical routes previously applied to C60. Until today all reaction schemes that involve N@C60 have resulted to some degree of electron spin signal loss during the reaction. In this talk, I will present our recent results for two cyclopropanation reactions that remarkably preserve all electron spin signal. The proposed methodology is facile and very effective. The reaction scheme can be successfully applied to both low-purity N@C60/C60 mixture and also significantly enriched material with very intense electron spin resonance (ESR) signal. I will show quantitative ESR evidence to support the above claim and I will propose a mechanism for suppressing any electron spin signal loss. I believe these results open up the road for more elaborate reaction schemes to be applied to N@C60 and for the synthesis of multi spin-centre structures to be achieved. I will also provide an overview of the stability issues surrounding N@C60 and its derivatives.
Isoxazoline-Ring Fused Derivatives of Sc3n@C80 and C60: The Internal Effect on the Exohedral Configuration
Authors: Bao Lipiao , Olmstead Marilyn M. , Balch Alan L. , Lu Xing
Published: February 2020

Fullerenes are unique among all carbon allotropes as their molecular structures can be fully confirmed by single-crystal X-ray diffraction. With metal atoms or metal complexes encapsulated, endohedral metallofullerenes (EMFs) redistribute electrons between the internal unit and the cage, and thus afford different electronic structures and different chemical properties compared to empty fullerenes. However, because of the relatively low yield of endohedral metallofullerenes, only a limited number of chemical modifications have been reported for them. In this work, an isoxazoline ring was added to Sc3N@C80 for the first time to form only one mono-adduct with high regio-selectivity (2b). An analogous product was obtained for empty cage C60 (2a).

X-ray crystallography has revealed their structures, as shown in Fig. 1. The addition site of exohedral moieties of C60 was the [6,6]-bond while it is a [5,6]-bond for Sc3N@C80. Inside the Sc3N@C80, disorder of the Sc atoms represents the dynamic motion of the cluster, and the sum of the three Sc–N–Sc angles (342°) suggests that the trimetallic nitride cluster slightly derives from a coplanar structure, confirming the motion control effect of the exohedral modification. Moreover, it is very interesting to find that the configuration of exohedral moieties differed in 2a and 2b.In detail, the methoxy indicated by the arrow shown in Fig. 1 occurs at opposite sides of the benzene plane. These results reveal the significant internal effect on the exohedral configuration.

Figure 1. Drawings of 2a and 2b showing thermal ellipsoids at the 30% probability level. Arrows indicate the special methoxy group that changes conformations when added to different fullerenes. Solvent molecules are omitted for clarity.

Figure 1
Carbon Nanostructures and Perylenediimides
Authors: Sastre-Santos Angela , Martin-Gomis Luis , Rotas Giorgos , Karousis Nikolaos , Petsalakis Ioannis D. , Pla Sara , Fernández-Lázaro Fernando , Ohkubo Kei , Tagmatarchis Nikos , Fukuzumi Shunichi
Published: February 2020

The seeking for efficient molecular systems, based on the covalent combination of suitable and versatile building blocks, capable to mimic the photoinduced electron transfer that naturally occurs in photosynthesis, has been a constant in material science.[1] In a simplistic definition, a molecular system which combines an electron-acceptor moiety with an electron-donor counterpart, able to be excited by the action of light, can be considered as a potential photosynthetic system, and therefore useful for photovoltaic applications.

Among the large number of donor-acceptor molecules frequently used in the preparation of photo-electroactive molecular systems, carbon nanostructures (CNs) and perylenediimides (PDIs) stand out. So far, we can find examples where the CNs are covalently or supramolecularly attached to PDI subunits, thus combining the electrochemical and photophysical properties of the former with the electrochemical and light-absorption properties of the latter.[2] In most of the cases, both sytems are electron deficient and energy transfer between them is observed. However, to the best of our knowledge, the synthesis of CN-PDI where the PDI acts an electron donor has only been briefly described. This kind of systems is quite interesting because it will be possible to study the influence of the electronic interaction between both units in different configurations.

Herein, we will report our more recent results related with the synthesis of different carbon nanostructure-perylenediimide arrays where the PDI acts as an electron-donor system (see Figure 1 as example), focussing mainly in the photoinduced electron transfer properties for their application as artificial photosynthetic systems and in organic photovoltaics.[3]

                       

Acknowledgements. This work has been supported by the Spanish Ministerio de Economía y Competitividad, Generalitat Valenciana and the European FEDER funds (grants CTQ2011-26455, PROMETEO 2012/010 and ISIC/2012/008)

  References

1.  (a) El-Khouly, M. E.; Fukuzumi, S.; D’Souza, F. ChemPhysChem, 2014, 15, 30.

 2. Zhan, X.; Facchetti, A.; Barlow, S.; Marks, T. J.; Ratner, M. A.; Wasielewski, M. R.; Marder, S. R. Adv. Mater.
2011, 23, 268.

3. (a) Martín-Gomis, L.;

Giorgo, R.; Ohkubo, K.; Fernández-Lázaro, F.;

Tagmatarchis, N.; Fukuzumi S.; Sastre-Santos Á. Submitted. (b) Martín-Gomis, L.; Karousis, N.; Petsalakis, I. D.; Ohkubo, K.; Fernández-Lázaro, F.;

Tagmatarchis, N.; Fukuzumi S.; Sastre-Santos Á. Submitted.

Figure 1. Chemical structure of [60]Fullerene-PDI system

Figure 1