bluuebunny/crossref_metadata_2025_split huggingface dataset:
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
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.
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
Unveiling the Nature of Supramolecular Crown Ether-C60 Interactions
Authors: Moreira Luis , Calbo Joaquín , Krick Calderon Rafael M. , Santos José , Illescas Beatriz M. , Aragó Juan , Nierengarten Jean-François , Guldi Dirk M. , Ortí Enrique , Martin Nazario 
Published: February 2020

Construction of artificial photoactive devices capable of mimicking photosynthesis by transforming light into chemical potential is one of the most sought objectives in the quest for new sources of energy.[1] For this, chemists have developed a wide variety of covalent and supramolecular structures based on donor-acceptor systems where photon energy is used to produce a photoinduced electron-transfer from the donor to the acceptor moiety.[2]

As a result, in 2010 our group developed a supramolecular exTTF-B18C6 ether receptor for fullerenes which showed an extraordinary affinity (K
a 5.01 × 106 M-1) towards [60]fullerene.[3]This was an outstanding result as previous attempts to complex fullerenes by only one unit of exTTF were unsuccessful. Thus, the presence of crown ethers as recognition patterns seemed to be of paramount importance.
In this work, we have further studied this unexpected result and exploited the potentiality of crown ethers as recognition motifs for fullerenes. Therefore, a series of exTTF-(crown ether)2 receptors, designed to host C60, has been prepared. The size of the crown ether and the nature of the heteroatoms have been systematically changed to fine tune the association constants. Electrochemical measurements and transient absorption spectroscopy assisted in corroborating a charge transfer in the ground state and in the excited state leading to the formation of radical ion pairs featuring lifetimes in the range from 12 to 21 ps. To rationalize the nature of the exTTF-(crown ether)2•C60 stabilizing interactions, theoretical calculations have been carried out, prompting to a synergetic interplay of donor-acceptor, π-π, n-π and CH···π interactions, which is the basis for the affinity of our novel receptors towards C60.

References:

[1] J. L. Delgado, P.-A. Bouit, S. Filippone, M. A. Herranz, N. Martín, Chem. Commun. 2010, 46, 4853-4865.
[2] H. Dong, H. Zhu, Q. Meng, X. Gong, W. Hu, Chem. Soc. Rev.
2012, 41, 1754-1808.
[3] B. Grimm, J. Santos, B. M. Illescas, A. Muñoz, D. M. Guldi, N. Martín, J. Am. Chem. Soc.
2010, 132, 17387-17389.

Figure 1
Carboxylate Fullerene Derivatives in Redox-Reversible Bimetallic Assemblies
Authors: Suarez Catalina , Rivera-Nazario Danisha Marie , Echegoyen Luis 
Published: February 2020

Supramolecular assemblies containing bimetallic units displaying paddlewheel motifs are well known, especially Zn2 and Cu2. However, assemblies containing stable, electrochemically active and reversible bimetallic units are scarce, and their physicochemical properties are not well studied. These bimetallic units (e.g. Cr2, Mo2, Ru2 and W2) possess very rich electrochemical properties and exhibit multiple bonding between the metal atoms. Fullerenes containing carboxylic acid addends are excellent candidates to complement the bimetallic units due to their rich and stable redox properties. We successfully synthesized and characterized three different carboxylate fullerene derivatives. After we preassembled a Secondary Building Unit (SBU) using labile bridging ligands such as formamidinates, carboxylates and acetonitriles, we prepared a series of new discrete molecular systems containing the synthesized fullerene derivatives (See image below) and studied their electrochemical properties. Of particular interest is the degree of electronic coupling between the fullerenes and through the metallic centers via the carboxylate connections. In the future, discrete bimetallic assemblies will be extended to form Metal Organic Frameworks (MOFs).

Figure 1
Preparation and Photophysical Properties of Molecular Architectures Composed of Polycyclic Aromatic Hydrocarbon and Porphyrin Derivatives
Authors: Hasobe Taku 
Published: February 2020

The self-assembly of organic molecules to form ordered nanoarchitectures is currently receiving great interest as a means of constructing well-defined nanostructures. The possibility for controlling macroscopic structures through a proper choice of the molecular components paves a way to design and synthesize materials with specific properties and functions. One of the main challenges is the consturction of highly organized supramolecular multicomponent nanostructures in a well-controlled manner, which is very related to the molecular systems of natural photosynthesis highly organized in quaternary protein structures. Therefore, utilization of electron donor (D) and acceptor (A) molecules such as polycyclic aromatic hydrocarbon derivatives (PAHs) (e.g., perylene and coronene) for controlled assembly has stimulated the related research fields such as molecular electronics and light energy conversion.1-3

Disc-like PAH derivatives such as triphenylene functionalized with alkyl chains, which self-assemble into supramolecular structures due to the stacking π−πinteractions, may be a good candidate to construct face-to-face complexes with planar dye molecules. In this context, 1,4,5,8,9,12-hexaazatriphenylene (HAT) derivatives are good electron acceptors since these molecules have the electron deficient pyrazine units.
Along this point, planar porphyrins and 1,4,5,8,9,12-hexaazatriphenylene (HAT) derivatives are expected to form supramolecular charge-transfer (CT) π-complexes, exhibiting broad CT absorption bands. The redox properties of porphyrins and HAT derivatives measured by electrochemical measurements indicate that porphyrins and HAT derivatives act as electron donors and acceptors, respectively. The 1 : 1 CT complexes between porphyrins and HAT derivatives was successfully examined by the UV-vis, fluorescence and 1H NMR measurements. The occurrence of ultrafast photoinduced electron transfer from the porphyrin unit to the HAT unit was confirmed by transient absorption measurements. Finally, highly one-dimensional assembly composed of porphyrin and an HAT derivatives was observed by transmission electron microscope (TEM) and atomic force microscope (AFM).
Additionally, the related molecular architectures containing fullerene derivatives will be also discussed in this presentation.

References

(1) Hirayama, S.; Sakai, H.; Araki, Y.; Tanaka, M.; Imakawa, M.; Wada, T.; Takenobu, T.; Hasobe, T. Chem. Eur. J.
2014, 20, 9081.
(2) Ida, K.; Sakai, H.; Ohkubo, K.; Araki, Y.; Wada, T.; Sakanoue, T.; Takenobu, T.; Fukuzumi, S.; Hasobe, T. J. Phys. Chem. C
2014, 118, 7710.
(3) Sakai, H.; Shinto, S.; Araki, Y.; Wada, T.; Sakanoue, T.; Takenobu, T.; Hasobe, T. Chem. Eur. J.
2014,
20, 10099.
Photo-Physical Properties and Applications of Multi-Porphyrinic Polypeptides
Authors: Solladie Nathalie 
Published: February 2020

In honor of Prof. Fukuzumi.
One of our research field concerns porphyrin-functionalized α-polypeptides to control the spatial organization of the chromophores and enable exciton migration through the pool of porphyrins to mimic the light harvesting antennae of the photosynthetic system.1

In the photosynthetic system, the solar energy is collected by pigment molecules attached to the light harvesting complexes, in which the chlorophylls are held in a parallel orientation by fairly short α-helical polypeptides. When a photon hits one of the chlorophylls, the absorbed energy spreads extremely rapidly to the others until the reaction center is reached.1 Succeeding in organizing the porphyrins in a similar way as nature does should provide information about the relation existing between the orientation of the chlorophylls and the efficiency of nature in transferring an excited state over a very long distance and with minimal loss of energy.
The right-handed 310helical conformation adopted by our poly-L-lysine functionalized with eight porphyrins induces an overlap of the chromophores (studies realized in collaboration with Prof. T. Keiderling, University of Chicago, US), which thus present sufficient electronic coupling to promote a good exciton migration within the molecular wire.
The properties of our peptides with pendant porphyrins were studied extensively in collaboration with with Professor S. Fukuzumi (Univeristy of Osaka, Japan) and applications were found as organic photovoltaic cells,2 multiple photosynthetic reaction centers3 and for the successful purification of Single-Walled Carbon Nanotubes.4

Acknowledgements

This work was supported by the CNRS and the French Ministry of Research.

References

W. Kühlbrandt, Nature
1995, 374, 497-498.

T. Hasobe, K. Saito, P. V. Kamat, V. Troiani, H. Qiu, N. Solladié, K. S. Kim, J. K. Park, D. Kim, F. D'Souza, S. Fukuzumi, J. Mater.
Chem.
2007, 39, 4160-4170.

S. Fukuzumi, K. Saito, K. Ohkubo, V. Troiani, H. Qiu, S. Gadde, F. D’Souza and N. Solladié, Phys.
Chem. Chem. Phys.
2011, 13, 17019-17022.

Kenji Saito, Vincent Troiani, Hongjin Qiu, Nathalie Solladié, Takao Sakata, Hirotaro Mori, Mitsuo Ohama, Shunichi Fukuzumi, J. Phys. Chem. C 2007, 111, 1194-1199.

Figure 1
Fullerenes and Caps By Sequential HF Elimination from F-PAHs
Authors: Böttcher Artur , Weippert Jürgen , Ulas Seyithan , Weis Patrick , Greisch Jean-Francois , Amsharov Konstantin , Kappes Manfred 
Published: February 2020

Appropriately functionalized planar fluorinated polycyclic aromatic hydrocarbons (FPAHs) can be efficiently converted into curved carbon structures via a sequence of thermally activated, regioselective HF elimination steps. [1] On surfaces, such HF elimination is associated with a “planar-to-cap transition” which has been studied by scanning probe methods. [2] The resulting caps have recently been applied to the controlled growth of chirality-selected SWCNTs. [3] We have studied the mechanism of planar-to-curved conversion in a variety of active model FPAHs (C26H14F2, C36H15F3 and C60H21F9) using both laser induced desorption (LID) as well electron-impact ionization/heating/fragmentation (EIIHF). For all precursors, we observe sequential HF elimination to be the dominant fragmentation channel. Experiments performed on deposited products of the fragmentation cascade (e.g. C26H12), suggest that the pentagon-hexagon structure of the original FPAH carbon network rearranges during fragmentation. The energy flux deposited into the FPAHs is larger in LID than for EIIHF. As a result, the sequence of regioselective HF elimination steps can to be taken to completion - to form closed fullerene cages and/or fluorine-free carbon caps depending on the precursor FPAH. By combining LID with ion mobility measurements supported by DFT calculations, we have been able to determine the molecular structure of the (intermediate) fragments along the reaction path thus obtaining insight into the fragmentation mechanism.
[1] M. Kabdulov, et al. Chemistry - A European Journal 19 (2013) 17262
[2] K. Amsharov, et al. Angew. Chem. Int. Ed. 49 (2010) 9392
[3] J.R. Sanchez-Valencia, et al. Nature 61 (2014) 512
(Invited) Synthesis, Properties and Applications of Group IV Graphane Analogues
Authors: Jiang Shishi , Arguilla Maxx , Cultrara Nicholas , Goldberger Joshua E. 
Published: February 2020

In this talk, we will summarize our recent work on the synthesis, properties, and applications of a new family of two-dimensional materials based on sp3-hybridized Group IV elements. Ligand-terminated Si, Ge, and Sn graphane analogues are an emerging and unique class of two-dimensional materials that offer the potential to tailor the structure, stability, and properties via covalent chemistry. The presence of a fourth bond on the surface of the layers allows these materials to have the surface terminating ligand to be exchanged with a variety of organic functional groups. These materials feature a direct band gap which can be tuned with the surface ligand and the main group element. These materials can be synthesized as robust single crystals in gram-scale quantities, exfoliated into single layers, and prepared on conventional VLSI substrates as few-layer thin films. Furthermore, these graphane analogues are resilient towards oxidation and thermal degradation. Additionally, we will describe our recent studies on the electronic and thermal properties of these systems. Overall, this class of two-dimensional materials are not only promising building blocks for a variety of conventional semiconductor applications, but also provides a pioneering platform to systematically and rationally control material properties using covalent chemistry.