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Connecting and combining rules of aromaticity. Towards a unified theory of aromaticity
WIREs Comput Mol Sci, 2019, 9, e1404
Marta Izquierdo, Benedikt Platzer, Anton J. Stasyuk, Olga A. Stasyuk, Alexander A. Voityuk, Sergio Cuesta, Miquel Solà, Dirk M. Guldi, Nazario Martín
All-Fullerene Electron Donor-Acceptor Conjugates
Angew. Chem. Int. Ed., 2019, 58, 6932-6937
Jesús Antonio Luque-Urrutia, Miquel Solà, David Milstein, Albert Poater
Mechanism of the Manganese-Pincer-Catalyzed Acceptorless Dehydrogenative Coupling of Nitriles and Alcohols
J. Am. Chem. Soc., 2019, 141, 2398-2403
Ouissam El Bakouri, Verònica Postils, Marc Garcia-Borràs, Miquel Duran, Josep M. Luis, Simone Calvello, Alessandro Soncini, Eduard Matito, Ferran Feixas, Miquel Solà
Metal Cluster Electrides: a new Type of Molecular Electrides with Delocalised Polyattractor Character
Chem. Eur. J., 2018, 24, 9853-9859
Marc Garcia-Borràs, Maira R. Cerón, Sílvia Osuna, Marta Izquierdo, Josep M. Luis, Luis Echegoyen, Miquel Solà
The Regioselectivity of Bingel-Hirsch Cycloadditions on Isolated Pentagon Rule Endohedral Metallofullerenes
Angew. Chem. Int. Ed., 2016, 55, 2374-2377
Aromatic species have rings or closed structures characterized by high electronic delocalization. With this in mind, our group has been pioneering in analyzing the aromaticity of classical aromatic and heteroaromatic compounds through electronic-based aromaticity measures. We have developed new aromaticity indices like PDI, FLU, INB and ING for such purpose, which perfectly complement others like the geometrical HOMA or the magnetic NICS. More recently, we have analyzed these heteroaromatic compounds (with especial emphasis of the corresponding isomerization energies) by means of Morokuma-like energy decomposition analysis and the turn-upside-down approach.
In the last decades the study of aromaticity has experienced an enormous progress. The new discoveries include species such as the metallabenzenes, heterometallabenzenes, metallabenzynes, metallabenzenoids, metallacyclopentadienes, metallacyclobutadienes and all-metal and semimetal clusters. These new molecules, which are potentially useful for certain purposes as specific and very efficient catalysts, molecular electronic devices, molecular magnets, drugs, and other as yet unimagined applications, have brought a complete revolution in the field. At variance with the classical aromatic organic molecules that possess only ?-electron delocalization, aromaticity in these new species is much more complex. These compounds have ?-, ?-, ?- and ?-electron delocalization. In addition, they can combine different types of aromaticity thus giving rise to double or triple aromaticity, the so-called multifold aromaticity. The new molecules can also have conflicting aromaticity, i.e., they can be aromatic in one component and antiaromatic in another. Moreover, most of the old indicators are not valid to discuss the complex aromaticity of these novel compounds. The analysis of metalloaromaticity in our group follows two main directions. First, we discuss the metalloaromaticity and the molecular properties of metallacycles and all-metal and semimetal clusters. And second, we aim to find reliable measures of aromaticity in these systems. In particular the use of multicenter electronic delocalization indices is advocated because they help to detect the different types of aromaticity and provide reasonable qualitative orderings of aromaticity.
Aromaticity is a concept of capital importance in chemistry: it governs chemical reactions, attributes extra stabilization to molecular structures and assigns exalted magnetic properties. Unfortunately, there is not a unique way to account for aromaticity and, as a result, many indices accounting for different manifestations of aromaticity are available in the literature. Our group has actively worked in the construction of new electronic aromaticity indices departing from the fact that aromaticity is related to cyclic electronic delocalization. For such, we have suggested several new measures, including PDI, FLU, INB and ING indices. Interestingly, the last two use the so-called multicenter indices, which have been proven to perform the best in different chemical enviroments (from organic to all-metal aromatic compounds), together with the magnetic-based nucleus independent chemical shifts (NICS).
In this line of research we carry out extensive mechanistic studies, i.e. we determine the reaction path followed from reactants to products, with localization of intermediates and transition states in organometallic and bioinorganic reactions. Most of the mechanisms investigated in this research line yield products of special interest either at large-scale manufacturing or because of their properties as powerful drugs, antibiotics or anticancer agents. Since in these cases obtaining the desired product (or, on the contrary, of an undesired by-product) can represent a gain (or a loss) of many million dollars every day, and since the final result is mainly governed by the path followed by the reaction, there is a great incentive to improve the understanding of the details of the operative mechanism of a given chemical process.
Fullerene-based architectures are being intensively studied as electron acceptor materials in the construction of plastic photovoltaic cell devices because of their unique structural and electron acceptor properties. Organic solar cells containing fullerenes have already been commercialized but the current power conversion efficiency (PCE) achieved is less than 10%. Most of the fullerene-based photovoltaic cells are based on the bulk heterojunction concept, where a donor is blended with a fullerene-based derivative that acts as acceptor. Possible alternatives to improve the current efficiencies in such organic solar cells involve the covalent linkage of the donor molecule with the fullerene surface. The covalent functionalization of the donor molecule to fullerenes and EMFs is mainly achieved via cycloaddition reactions, principally through Diels-Alder (DA), 1,3-dipolar (Prato) and nucleophilic [2+1] Bingel-Hirsch (BH) cycloaddition. In this project, we aim to computationally design new donor-acceptor conjugates with the ability to efficiently generate long-live charge separated states with lifetimes comparable to those observed in natural photosynthetic systems. To that aim, we explore the exohedral reactivity of several donor-acceptor systems based on empty fullerene cages and on EMFs to investigate the thermal stability of the adducts, the effect of the donor position with respect to the fullerene cages, and the ability to form photoinduced charge separated states.
ICREA Research Professor
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The IQCC is starting a new series of online talks to address challenges in
Well-defined fullerene-PEG conjugates, C60-PEG (1) and two C70-PEG (2 and 3 with the addition sites on ab-[6,6]
The journal Journal of Materials Chemistry C features on its front cover the
Dr. Sergio Posada-Pérez has recently become a new member of the Institute of