ORALS

SESSION: NanomaterialsWedAM-R3	Echegoyen International Symposium (8th Intl. Symp. on Synthesis & Properties of Nanomaterials for Future Energy Demands)
Wed. 29 Nov. 2023 / Room: Dreams 3
Session Chairs: Tomas Torres; Josep Maria Poblet; Session Monitor: TBA

12:00: [NanomaterialsWedAM02] OS
ACTINIDE ENDOHEDRAL METALLOFULLERENES
Josep Maria Poblet¹ ; ¹Universitat Rovira i Virgili, Tarragona, Spain;
Paper Id: 28 [Abstract]

For almost two decades, intensive work from experimental and theoretical groups has made it possible to advance in the understanding of structural and electronic properties of endohedral metallofullerenes and cluster metal fullerenes. Hence, several groups have proposed diverse rules related with the relative stability of fullerene cages.[1] All of them considered the potential energy when they predict the stability of IPR and non-IPR isomers based on the ionic model, in which the guest transfers usually between three and six electrons to the hosting carbon cage. Those guidelines have explained why the highly symmetric C80(Ih) cage is the preferred fullerene when there is a transfer of six electrons, like in the well-known Sc3N@C80,[2] or in many other examples, such as Lu3N@C80, La2@C80, Y3@C80, etc.[3] In endohedral fullerenes with four or less electron transfer between host and guest, there is not a prevalent structure, like C80(Ih), and the diversity of captured carbon cages is larger, the theoretical prediction of the most abundant species to be formed in a K-H reactor being much more difficult. In addition to the relative potential energy, it is also necessary to consider the enthalpic and entropic contributions to the stability of the endohedral fullerenes. A systematic theoretical analysis for a series of A@C2n fullerenes with A = Th and U, in combination with accurate experimental characterization, have allowed us to show that the structures of A4+@C2n4- species are different from those of cluster fullerenes, such as Sc2O4+@C2n4-, Sc2S4+@C2n4-or Sc2C24+@C2n4-.[4] Here, we will present some of the most recent studies carried out in collaboration with Prof. Luis Echegoyen concerning to stabilization of non-IPR, formation of strong covalent actinide-actinide bons and electrochemical reactions in endofullerenes.[5]

References:
[1] Campanera, J. M.; Bo, C.; Poblet, J. M., Angew. Chem., Int. Ed. 2005, 44, 7230-7233; Rodríguez-Fortea, A.; Alegret, N.; Balch, A. L.; Poblet, J. M., Nature Chem. 2010, 2, 955; Garcia-Borràs M., Osuna S., Swart M., Luis J.M., Solà M. Angew. Chem. Int.. Ed. 2013, 52, 9275-9278; Wang, Y.; Díaz-Tendero, S.; Martín, F. and Alcamí, M. J. Am. Chem. Soc., 2016, 138, 1551–1560 [2] Stevenson, S.; Rice, G.; Glass, T.; Harich, K.; Cromer, F.; Jordan, M. R.; Craft, J.; Hadju, E.; Bible, R.; Olmstead, M. M.; Maitra, K.; Fisher, A. J.; Balch, A. L.; Dorn, H. C., Nature 1999, 401, 55. [3] Popov, A. A.; Yang, S.; Dunsch, L., Chem. Rev. 2013, 113, 5989-6113. [4] W. Cai, L. Abella, J. Zhuang, X. Zhang, L. Feng, Y. Wang, R. Morales-Martínez, R. Esper, M. Boero, A. Metta-Magaña, A. Rodríguez-Fortea, J. M Poblet, L. Echegoyen, N. Chen J. Am. Chem. Soc. 2018, 140, 18039-18050. [5] X. Zhang, Y. Wang, R. Morales-Martínez, J. Zhong, C. de Graaf, A. Rodríguez-Fortea, J. M Poblet, L. Echegoyen, L. Feng, N. Chen J. Am. Chem. Soc. 2018, 140, 3907-3915; A. Moreno-Vicente, Y. Roselló, N. Chen, L. Echegoyen, P.W. Dunk, A. Rodríguez-Fortea, C. de Graaf, J. M Poblet, J. Am. Chem. Soc. 2023, 145, 6710-6718.

SESSION: NanomaterialsWedPM2-R3	Echegoyen International Symposium (8th Intl. Symp. on Synthesis & Properties of Nanomaterials for Future Energy Demands)
Wed. 29 Nov. 2023 / Room: Dreams 3
Session Chairs: Francis D'Souza; Emilio Palomares; Session Monitor: TBA

17:15: [NanomaterialsWedPM212] OS
COMPLEXES OF SEMICONDUCTOR FRAGMENTS FOR SOLAR-LIGHT REDUCTION OF CO2 BY WATER
Ira Weinstock¹ ; Guanyun Zhang² ; Josep Maria Poblet³ ; Chandan Tiwari⁴ ; Shubasis Roy⁵ ; Mark Baranov⁵ ; ¹Ben-Gurion U. of the Negev, Beer Sheva, Israel; ²Shandong University, Ji'nan, China; ³Universitat Rovira i Virgili, Tarragona, Spain; ⁴Carestream Health Inc., Saint Paul, United States; ⁵Ben-Gurion University of the Negev, Beer Sheva, Israel;
Paper Id: 49 [Abstract]

While recent advances in functional materials increasingly involve the inclusion of metal-oxide domains [1], reproducibility problems inherent to their incorporation remain an often success-limiting challenge. In this context, molecular science could play a transformative role by using the tractability and versatile solution-state chemistries of well-defined molecular complexes to simplify device fabrication. This is demonstrated by using coordination complexes of structurally and electronically recognizable fragments of bulk metal oxides as versatile molecular "modules" for replacing the parent materials. For example, soluble hexaniobate complexed molecular fragments of cubic-spinel and monoclinic Co3O4 are highly active analogs of bulk cobalt oxide, with the HOMO and LUMO energies of the complexes, 1, closely matching those of the valence- and conduction-bands of the parent bulk oxides. Use of 1 as a tractable analog of cobalt-oxide nanocrystals is demonstrated by its deployment as a co-catalyst for the direct Z-scheme reduction of CO2 by solar light and water [2]. Alternatively, complexed semiconductor cores can activate molecular polyoxoniobate cluster-anion ligands themselves as nucleophilic sites for CO2 reduction. Although pure and functionalized solid-state polyniobates such as layered perovskites and niobate nanosheets are photocatalysts for renewable-energy processes [3], analogous reactions by molecular polyoxoniobates are nearly absent from the literature. Under simulated solar-light, however, hexaniobate cluster-anion encapsulated 30-NiII-ion "fragments" of surface-protonated cubic-phase-like NiO cores activate the hexaniobate ligands themselves. Photoexcitation of the NiO cores promotes charge-transfer reduction of NbV to NbIV, increasing electron density at bridging oxo atoms of Nb–&#m181;-O–Nb linkages that bind and convert CO2 to CO. Photogenerated NiO “holes” simultaneously oxidize water to dioxygen. In related work, hexaniobate ligands are used to arrest the growth of metal-oxide NCs and stabilize them as water-soluble complexes. This is exemplified by hexaniobate-complexed 2.4-nm monoclinic-phase CuO NCs, whose ca. 350 Cu-atom cores feature quantum-confinement effects [4] that impart an unprecedented ability to catalyze visible-light water oxidation with no added photosensitizers or applied potentials, and at rates exceeding those of hematite NCs [5]. Together, the above findings point to polyoxoniobate-ligand entrapment as a potentially general method for harnessing the catalytic activities of semiconductor fragments as the cores of versatile, entirely-inorganic complexes.

References:
(1) Li, X.; Yu, J.; Jaroniec, M.; Chen, X. Cocatalysts for Selective Photoreduction of CO₂ into Solar Fuels. Chem. Rev. 2019, 119, 3962-4179. (2) Zhang, W.; Mohamed, A. R.; Ong, W.-J. Angew. Chem. Int. Ed. 2020, 59, 22894-22915. (3) Nishioka, S.; Hojo, K.; Xiao, L.; Gao, T.; Miseki, Y.; Yasuda, S.; Yokoi, T.; Sayama, K.; Mallouk, T. E.; Maeda, K., Science Advances, 2022, 8, eadc9115. (4) M. A. Holmes, T. K. Townsend, F. E. Osterloh, Chem. Commun. 2012, 48, 371-373. (5) S. Corby, R. R. Rao, L. Steier, J. R. Durrant, Nat. Rev. Mater. 2021, 6, 1136-1155.

SESSION: NanomaterialsThuAM-R3	Echegoyen International Symposium (8th Intl. Symp. on Synthesis & Properties of Nanomaterials for Future Energy Demands)
Thu. 30 Nov. 2023 / Room: Dreams 3
Session Chairs: Miguel A. Alario Franco; Mark Hersam; Session Monitor: TBA

12:50: [NanomaterialsThuAM04] OL
MULTIPURPOSE SUPRAMOLECULAR NANOCAPSULES: FROM PURIFICATION OF URANIUM-BASED EMFS TO MASKS FOR FULLERENE REGIOFUNCTIONALIZATION
Xavi Ribas¹ ; Josep Maria Poblet² ; Luis Echegoyen³ ; Carles Fuertes-Espinosa¹ ; ¹University of Girona, Girona, Spain; ²Universitat Rovira i Virgili, Tarragona, Spain; ³University of Texas El-Paso, El Paso, United States;
Paper Id: 423 [Abstract]

The design of supramolecular capsules with large cavities is attractive because they feature potential advantages as platforms to selectively bind large guests, such as fullerenes and Endohedral Metallofullerenes (EMFs).1 Generally, the practical applications of EMFs are hampered by their limited availability. Furthermore, their chromatographic purification (HLPC) is very challenging  and in some cases it is not successful. Our group reported a porphyrin-based supramolecular tetragonal prismatic nanocapsule (1),2 which features an internal cavity with size complementary and electrostatic relationship specific for a brand new family of Uranium-based EMFs.3 Nanocapsule 1 is able to sequentially and specifically recognize U2@Ih-C80 and Sc2UC@Ih-C80 among all those compounds present in the crude, simply by soaking crystals in a solution of the reaction crude. The stepwise and selective encapsulation of U-based EMFs allowed their separation and further purification by solvent-washing, obtaining highly pure fractions of the desired compounds in one step. Follow-up studies with U-based C78 soots indicate that not only the internal clusterelectronics but also the shape of the carbon cages strongly influences the selectivity of the nanocapsule.Taking advantage of the tight binding of fullerenes in our porphyrin-based supramolecular tetragonal prismatic nanocapsules, these are used as supramolecular shadow masks to tame the over-reactivity of Bingel-Hirsch-type cyclopropanation reactions and, more importantly, to have full control on the equatorial regioselectivity and on the number of additions.4 Thus, exclusively equatorial bis-, tris- and tetrakis-C60 adducts using ethyl-bromomalonate are stepwise obtained and fully characterized (NMR, UV-vis and XRD). Furthermore, the regioselectivity control is finely tuned using a three-shell Matryoshka-like assembly towards the synthesis of a single trans-3 bis-Bingel-C60 for the first time.5 These results, fully attributed to the confinement control imposed by the capsule’s cavity, represent a novel and unique strategy to infer regio-control to the synthesis of fullerene multi-adducts. We envision that the described protocol will produce a plethora of derivatives for applications such as solar cells.

 

References:
[1] C. Fuertes-Espinosa, M. Pujals and X. Ribas, Chem, 2020, 6, 3219-3262.
[2] C. García-Simón, M. Garcia-Borràs, L. Gómez, T. Parella, S. Osuna, J. Juanhuix, I. Imaz, D. Maspoch, M. Costas and X. Ribas, Nat. Commun., 2014, 5, 5557
[3] C. Fuertes-Espinosa, A. Gómez-Torres, R. Morales-Martínez, A. Rodríguez-Fortea, C. García-Simón, F. Gándara, I. Imaz, J. Juanhuix, D. Maspoch, J. M. Poblet, L. Echegoyen and X. Ribas, Angew. Chem. Int. Ed., 2018, 57, 11294-11299
[4] C. Fuertes-Espinosa, C. García-Simón, M. Pujals, M. Garcia-Borràs, L. Gómez, T. Parella, J. Juanhuix, I. Imaz, D. Maspoch, M. Costas and X. Ribas, Chem, 2020, 6, 169-186
[5] E. Ubasart, O. Borodin, C. Fuertes-Espinosa, Y. Xu, C. García-Simón, L. Gómez, J. Juanhuix, F. Gándara, I. Imaz, D. Maspoch, M. von Delius and X. Ribas, Nat. Chem., 2021, 13, 420-427