M.Sci. Jagiellonian University, 1976
Ph.D. Jagiellonian University, 1982
The discovery of a new allotropic form of elemental carbon – the fullerenes – and, subsequently, other novel forms of elemental carbon with pyramidalized sp2 hybridized atoms, including carbon nanotubes, spawned a renewed interest in curved-surface polynuclear aromatic hydrocarbons having carbon frameworks structurally related to fullerenes, known as “buckybowls” or “fullerene fragments”. The smallest buckybowl is corannulene, a C20H10 hydrocarbon representing the polar cap of fullerene C60.
Several larger buckybowls were prepared in our laboratory, most notably cyclopentacorannulene (CPC, C22H10) and two isomeric semibuckminsterfullerenes (C30H12), each representing one-half of a C60 carbon cage. All these hydrocarbons adopt highly nonplanar bowl-shaped conformations.
The buckybowls, shown above, were originally prepared by a small-scale flash vacuum pyrolysis methodology. More recently, we (and other research groups) have focused on the more practical solution-phase procedures. A major breakthrough came with the serendipitous discovery in our laboratory of an inexpensive and simple method leading to the formation of the corannulene framework by the base-promoted dehydrobromination of fluoranthene precursors.
The availability of corannulene on a multigram scale allowed for the preparation of its several derivatives including isocorannulenofuran (a reactive Diels-Alder diene) and 2-TMS-corannulenyl triflate, the precursor for “corannulyne”, a very reactive dienophile. Employment of the synthons has produced a number of large molecular architectures with corannulene subunits.
Molecular Clips and Tweezers with Corannulene Pincers
The accessible concave surfaces of buckybowls make them the potential candidates for the efficient molecular receptors for fullerenes with the ability to recognize the convex surfaces of the carbon cages through the “ball-and-socket” p – p interactions. However, the lack of experimental evidence for the formation of concave-convex stacked supramolecular assemblies of corannulenes with fullerenes in solution indicates that the attractive dispersion interaction of a single corannulene bowl with the convex surface of a fullerene cage is not large enough to overcome the expected entropy and solvation penalties associated with the dimeric complex formation. We have overcome the problem by designing the molecular receptors for fullerenes with two or more corannulene pincers preorganized on a proper tether. In 2007 the first “Buckycatcher” prepared in our laboratory exhibited a strong affinity toward C60 both in the solid state and in solution. The first experimental evidence for then efficient binding of fullerenes by dispersion-based concave-convex interactions, published in J. Am. Chem. Soc., was announced in the “Research Highlights” by Nature, Chem. Eng. News and Nature Nano. The original paper has been cited over 300 times.
Since that time, we have reported a series of Buckycatchers with two or three corannulene pincers, which exhibit even stronger affinities toward fullerenes than the original Buckycatcher I, by carefully changing the topology of the tethers. We are currently pursuing the possibilities of attaching our receptors to the solid surfaces which would produce the novel materials with the potential applications in catalysis, separation sciences, and photovoltaics.
We are looking for two quality graduate students interested in organic synthesis and/or in physical organic chemistry. The physical part of our research includes the studies of supramolecular assemblies of our molecular receptors with various guest molecules by the spectroscopic methods like NMR, UV-Vis, etc. and by computational methods.
1. Sygula, A. (2016) Invited auto-review “Corannulene-Adorned Molecular Receptors for Fullerenes Utilizing p-p Stacking of the Curved-Surface Conjugated Carbon Networks. Design, Synthesis and Testing” SYNLETT 27, 2070-2080.
2. Kumarasinghe, K.G.U. R.; Fronczek, F. R.; Valle, H. U.; Sygula, A. (2016) “Bis-corannulenoanthracene - an Angularly Fused Pentacene as a Precursor for Barrelene-tethered Receptors for Fullerenes” Org. Lett. 18, 3054-3057.
3. Abeyratne Kuragama, P. L.; Fronczek, F. R; Sygula, A. (2015) “Bis-corannulene Receptors for Fullerenes Based on Klärner’s Tethers: Reaching the Affinity Limits” Org. Lett. 17, 5292-5295.
4. Yanney, M.; Fronczek, F. R.; Sygula, A. (2015) “A 2:1 Receptor/C60 Complex as a Nanosized Universal Joint” Angew. Chem. Int. Ed. 54, 11153-11156.
5. Le, V. H.; Yanney,M.; McGuire, M.; Sygula, A., Lewis, E. A. (2014) ” Thermodynamics of Host-Guest Interactions Between Fullerenes and a Buckycatcher” J. Phys. Chem. B 2014, 118, 11956-11964.
6. Sygula, A.; Yanney, M.; Henry, W. P.; Fronczek, F. R.; Zabula, A. V.; Petrukhina, M. A. (2014) “Inclusion Complexes and Solvates of Buckycatcher, a Versatile Molecular Host with Two Corannulene Pincers” Cryst. Growth Des. 14, 2633-2639.
7. Zabula, A. V.; Sevryugina, Y. V.; Spisak, S. N.; Kobryn, L.; Sygula, R.; Sygula, A.; Petrukhina, M. A. (2014) “Unsolvated Buckycatcher and its First Dianion “ Chem. Commun. 50, 2657-2659.
8. Yanney, M., Sygula, A. (2013) “Tridental Molecular Clips with Corannulene Pincers: Is Three better than Two?” Tetrahedron Lett. 54, 2604-2607.
9. Janowski, T.; Pulay, P.; Karunarathna, A. A. S.; Sygula, A.; Saebo, S. (2011)“Concave-Convex Stacking of Curved Conjugated Networks: Benchmark Calculations on the Corannulene Dimer” Chem. Phys. Lett. 512, 155-160.
10. Sygula, A.; Collier, W. (2011) “Molecular Clips and Tweezers with Corannulene Pincers”
Chapter 1 in “Fragments of Fullerenes and Carbon Nanotubes: Design Synthesis, Unusual Reactions, and Coordination Chemistry” Petrukhina, M. A.; Scott, L. T., Eds.; Wiley; Hoboken, NJ, pp. 1- 40.
11. Mück-Lichtenfeld, C.; Grimme, S.; Kobryn, L., Sygula, A. (2010) “Inclusion Complexes of Buckycatcher with C60 and C70” Phys. Chem. Chem. Phys. 12, 7091-7097.
12. Sygula, A.; Fronczek, F. R.; Sygula, R.; Rabideau, P. W.; Olmstead. M. M. (2007)“A Double Concave Hydrocarbon Buckycatcher” J. Am. Chem. Soc. 129, 3842-3843.
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