corannulene and coronene

The specific π-π interactions between curved and planar structures, which are different from the general π-π interactions between planar arenes, have generated great attention due to their brand-new, unique, and fascinating photoelectric properties. Herein, the curved-planar (C-P) π-π interactions between corannulene, pyrene and coronene have been investigated using the DFT-D method. A series of structural and physical properties have been calculated including geometry, C-C distance, binding energy, population charge distribution, dipole moment, electrostatic potential (ESP), visualization of the interactions in real space, transfer integral, electronic transition behaviour and Raman shift. All the analyses indicate that the bowl-planar (C(B)-P) complexes are distinguishable from the mouth-tip-planar (C(M)-P) and planar-planar (P-P) packing motifs due to their coherent negative ESP, electronic attraction strength and Raman spectra. The C-P complexes are found to exhibit dominant electron transport characteristics. In addition, an unusual "negative Stokes shift" is found in the C-P π-π complexes, which is caused by state resonance. This provides a clue to help predict and explore the photoelectric properties of C-P π-π complexes. In particular, at the frequency of the out-of-plane CH bending vibration around 1400 cm(-1), the planar molecules in the C(B)-P complexes possess a smaller Raman peak shift than in the C(M)-P complexes, and vice versa for the curved molecules. This specific Raman shift can be utilized as characteristic signals to identify the C-P structures.

Topics: Polycyclic Aromatic Hydrocarbons; Polycyclic Compounds; Pyrenes; Quantum Theory; Static Electricity; Thermodynamics

π-π interactions are integral to many areas of chemistry, biochemistry, and materials science. Here we use electronic structure theory to analyze how π-π interactions change as the π-systems are curved in model complexes based on coronene and corannulene dimers. Curvature redistributes electronic charge in the π-cloud and creates a dipole moment in these systems, leading to enhanced intermolecular electrostatic interactions in the concave-convex (nested) geometries that are the focus of this work. Curvature of both monomers also has a geometric effect on the interaction by decreasing the average C-C distance between monomers and by increasing the magnitude of both favorable London dispersion interactions and unfavorable exchange-repulsion interactions. Overall, increasing curvature in nested π-π interactions leads to more favorable interaction energies regardless of the native state of the monomers, except at short distances where the most highly curved systems are less favorable as exchange repulsion terms begin to dominate the interaction.

Topics: Dimerization; Electrons; Polycyclic Aromatic Hydrocarbons; Polycyclic Compounds; Quantum Theory; Static Electricity

The application of set of homodesmotic reactions allowed us to estimate the aromatic stabilization energy (ASE) of corannulene and coronene. Appropriate reactions have been applied to balance syn/anti mismatches in di-, tetra- and hexamethylene substituted derivatives. Based on many different polycyclic reference structures that compensate the effect of strain in the corannulene moiety the value of ASE comes to 44.5 kcal mol(-1). Planar corannulene is more stabilized by cyclic π-electron delocalization by ca. 10.7 kcal mol(-1), as compared with a bowl-shaped system. A similar approach for coronene leads to an ASE equal to 58.4 kcal mol(-1).

Topics: Molecular Structure; Polycyclic Aromatic Hydrocarbons; Polycyclic Compounds; Thermodynamics

The Dang-Chang many-body polarizable potential has been used to model the interaction between water molecules and a cationic carbonaceous molecule X(+), with X = C(60) (buckminsterfullerene), C(24)H(12) (coronene), or C(20)H(10) (corannulene). The most stable structures of (H(2)O)(n)X(+), located with the basin-hopping method, consist of a water cluster next to the carbon cation but often deviate from those obtained for pure water clusters. The accuracy of the intermolecular potential is checked by performing dedicated high-level electronic structure calculations using the B97-1 density functional. Finally, some thermodynamical and dynamical manifestations of the nonwetting behavior are discussed.

Topics: Cations; Computer Simulation; Fullerenes; Hydrogen Bonding; Models, Chemical; Polycyclic Aromatic Hydrocarbons; Polycyclic Compounds; Water

Electron attachment to the polyaromatic hydrocarbons coronene and corannulene is studied in the electron energy range of about 0-14 eV using a high-resolution crossed electron-neutral beam setup. The major anions observed are the parent anions peaking at about 0 eV with cross sections of 3.8 x 10(-20) and 1 x 10(-19) m(2), respectively. The only fragment anions formed in coronene and corannulene are the dehydrogenated coronene and corannulene anions. Other anions observed in the negative mass spectra at about 0 eV can be ascribed to impurities of the sample. High-level quantum-mechanical studies are carried out for the determination of electron affinities, hydrogen binding energies, and structures of both molecules. The behavior of coronene and corannulene upon electron attachment is compared with that of other polyaromatic hydrocarbons studied previously.

Topics: Anions; Electrons; Gases; Models, Molecular; Polycyclic Aromatic Hydrocarbons; Polycyclic Compounds