Tailoring buckybowls for fullerene recognition
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Título: | Tailoring buckybowls for fullerene recognition |
Autor/a: | Josa, Daniela |
Dirección/Titoría: | Rodríguez Otero, Jesús Cabaleiro Lago, Enrique Manuel |
Outro/a autor/a: | Universidade de Santiago de Compostela. Facultade de Química. Departamento de Química Física. Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) |
Palabras chave: | Química computacional | Interacciones π···π cóncavo-convexo | Receptores moleculares para fulerenos | Fragmentos de fulerenos | Pinzas moleculares | |
Data: | 2015-09-28 |
Resumo: | Nowadays, the design and synthesis of fullerenes receptors is a very attractive field of research. Besides their great importance in the development of new materials in nanotechnology and nanoscience, fullerene receptors also could be crucial for separation of fullerenes. A promising strategy to design new molecular receptors for fullerenes is using the concave-‐convex complementarity. Nevertheless, the examples of concave fullerene receptors are relatively scarce since curved molecules are not always an easy synthetic target due their tensioned structures. In this context, bowl-‐shaped polycyclic aromatic hydrocarbons, commonly known as buckybowls or fullerene fragments seem very attractive because several buckybowls have been synthetized in recent years and their concave surface can fit adequately to the convex surface of fullerenes through concave-‐convex "ball-‐and-‐socket" π···π interactions. In 2007, Sygula and co-‐workers introduced a novel type of molecular tweezers (a buckycatcher, C60H28) with buckybowl pincers that have attracted a substantial interest of researchers due their ideal architecture for recognizing fullerenes and their potential future applications, in particular as stationary phases in liquid chromatography for the separation of fullerenes or as buckycatcher-‐fullerene complexes in photovoltaic devices (A. Sygula et al. J. Am. Chem. Soc. 2007, 129, 3842). Despite their great interest, the number of theoretical studies of concave-‐convex π···π interactions between buckybowls and fullerenes are limited due to the recent discovery of these structures, to their large size and, especially, to the fact that until a few years ago there were no satisfactory options for the precise calculation of the non-‐covalent interactions between large molecules. For that reason, the present doctoral thesis is focused in the detailed theoretical study of the concave-‐convex π···π interactions between buckybowls and fullerenes with ultimate goal of designing new molecular tweezers based in buckybowls for fullerene recognition. To this end, the objectives of this thesis are: (1) selecting a reliable level of calculation to study concave-‐convex π···π interactions; (2) evaluating the effects that can enhance the interaction between buckybowls and fullerenes. In particular, the addition of substituents and the curvature effects are evaluated; (3) evaluating the performance of the B97-‐D2//SCC-‐DFTB-‐D calculations regarding B97-‐D2 ones in order to obtain a rapid tool for selecting suitable strategies for the rational design of molecular tweezers; (4) trying to answer the key question: how to modify the buckycatcher C60H28 to improve its efficiency and/or selectivity? The methodology of quantum chemistry was used for this purpose. This methodology offers valuable interpretative information and it can provide very useful information to guide the design of new molecules that make use of concave-‐convex π···π interactions. Our results indicate that B97-‐D2 functional seems appropriate to study concave-‐convex π···π interactions. This model shows a good performance for corannulene dimer regarding to QCISD(T)/aug-‐cc-‐pVTZ calculations and it also enables the use of the RI approximation that takes advantage of the noticeable reduction of computational cost. In addition, the utilization of the SCC-‐DFTB-‐D method as starting guess enables considerable savings of the calculation time (almost 50% regarding the full B97-‐D2/TZVP optimization of the emblematic C60H28···C60 complex). The shape of the buckybowl plays a crucial role on its ability for fullerene recognition. Compounds whose structure possess flaps at the rim of the bowl show an enhanced capability for interacting with fullerenes. On the other hand, CH···π interactions also are very important in fullerene recognition. Finally, three different strategies have been tested in order to improve the efficiency of traditional molecular tweezers synthesized by Sygula et al.: (1) changing the corannulene pincers by other buckybowls, (2) replacing the tetrabenzocyclooctatetraene tether by a buckybowl, (3) adding methyl groups on the molecular tweezers. According to the results, the three approaches are effective, in such a way that combination of the three strategies results in buckycatchers with complexation energies (with C60) up to 2.6 times larger than that for the original buckycatcher, reaching almost -‐100 kcal/mol. |
URI: | http://hdl.handle.net/10347/13618 |
Dereitos: | Esta obra atópase baixo unha licenza internacional Creative Commons BY-NC-ND 4.0. Calquera forma de reprodución, distribución, comunicación pública ou transformación desta obra non incluída na licenza Creative Commons BY-NC-ND 4.0 só pode ser realizada coa autorización expresa dos titulares, salvo excepción prevista pola lei. Pode acceder Vde. ao texto completo da licenza nesta ligazón: https://creativecommons.org/licenses/by-nc-nd/4.0/deed.gl |
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- Área de Ciencias [947]
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Esta obra atópase baixo unha licenza internacional Creative Commons BY-NC-ND 4.0. Calquera forma de reprodución, distribución, comunicación pública ou transformación desta obra non incluída na licenza Creative Commons BY-NC-ND 4.0 só pode ser realizada coa autorización expresa dos titulares, salvo excepción prevista pola lei. Pode acceder Vde. ao texto completo da licenza nesta ligazón: https://creativecommons.org/licenses/by-nc-nd/4.0/deed.gl
Esta obra atópase baixo unha licenza internacional Creative Commons BY-NC-ND 4.0. Calquera forma de reprodución, distribución, comunicación pública ou transformación desta obra non incluída na licenza Creative Commons BY-NC-ND 4.0 só pode ser realizada coa autorización expresa dos titulares, salvo excepción prevista pola lei. Pode acceder Vde. ao texto completo da licenza nesta ligazón: https://creativecommons.org/licenses/by-nc-nd/4.0/deed.gl