Supramolecular Chemistry of Sumanene

Sumanene is a buckybowl molecule that is continuously attracting the attention of the scientific community because of its unique geometrical and physicochemical properties. This Minireview systematically summarizes advances and considerations regarding the applied supramolecular chemistry of sumanene. This work highlights the major fields in which potential or real applications of sumanene molecule have been reported to date, such as the design of sumanene-containing functional supramolecular materials and architectures, sumanene-based drug-delivery systems, or sumanene-tethered ion-selective molecular receptors. An assessment of the current status in the applied supramolecular chemistry of sumanene is provided, together with an emphasis on the key advances being made. Discussion on those milestones that are still to be achieved within this emerging field is also provided.

Accurate Analysis of Anisotropic Carrier Mobility and Structure-property Relationships in Organic BOXD Crystalline Materials

Charge mobility is an essential factor of organic crystalline materials. Although many investigators have made important progress, the exact relationship between the crystal structure and carrier mobility remains to be clarified. Fortunately, a series of bis-1,3,4-oxadiazole derivatives have been successfully prepared and reported. They have similar main molecular fragments but different crystal packing modes, which provide an ideal research objective for studying the effect of molecular packing on charge mobility in organic photoelectric conversion systems. In this work, the charge mobilities of these molecules are systematically evaluated from the perspective of first-principles calculation, and the effect of a molecular overlap on orbital overlap integral and final charge carrier mobility is fully discussed. It can be seen that the small intermolecular distance (less than 6 Å) is the decisive factor to achieve high electron mobility in π stacking, and better mobility can be obtained by increasing the hole migration distance appropriately. A larger dihedral angle of anisotropy is an important point limiting the charge mobility in the herringbone arrangement. It is hoped that the correlation results between the crystal structure and mobility can assist the experimental study and provide an effective way to improve the photoelectric conversion efficiency of the organic semiconductor devices and multiple basis for multiscale material system characterization and material information.

Theoretical study on the molecular stacking interactions and charge transport properties of triazasumanene crystals - from explanation to prediction

Computational analyses of the solid-state properties of triazasumanene (TAS), a C₃-symmetric nitrogen-doped sumanene derivative, were carried out in this work. The present studies are mainly divided into two parts. In the first part, we demonstrated the differences in the interactions of the crystal packing between the racemic and the homochiral structures: the former having perpendicular columnar packing and the latter forming slipped helical packing. Two geometries of the TAS monomer, a theoretically optimized structure under vacuum and an X-ray crystal structure in experiment, were compared. It can be found that it is not the total interaction energy, but the local interactions (mainly the electrostatic interactions) of the molecular dimer that dominate the columnar stacking conformation. The second part involves the investigation of the potential charge transport properties of the crystals according to the semiclassical Marcus theory with the hopping mechanism using the simple dimer model. The charge transfer integrals of the two sets of dimers, racemic and homochiral dimer models, were compared as well. The calculation results show that the TAS racemic crystal was predicted to have an advantage of hole transport properties. The perpendicular columnar stacking of the homochiral conformation should essentially have better charge transport properties than the racemic conformation. It is reasonable to employ the simple dimer model built using optimized monomers under vacuum for the purpose of the prediction of the molecular packing conformation by IES calculation and the charge transport properties of the perpendicular columnar-stacking crystal. Our work provides a simple approach to the deep understanding of the structure-property relationship of bowl-shaped molecular systems in theory. It can help to facilitate the design and preparation of heteroatom-doped sumanene derivatives with perpendicular columnar stacking crystals as novel organic semiconductor materials.

Adsorption mechanism of NH3, NO, and O2 molecules over the FexOy/AC catalyst surface: a DFT-D3 study

The surface model of the Fe_xO_y/AC catalyst was constructed and the adsorption mechanism of gas molecules on its surface was revealed.

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

Since the first synthetic report in 2003 by Sakurai et al., sumanene (derived from the Indian 'Hindi as well as Sanskrit word' "Suman", which means "Sunflower"), a beautifully simple yet much effective bowl-shaped C 3-symmetric polycyclic aromatic hydrocarbon having three benzylic positions clipped between three phenyl rings in the triphenylene framework has attracted a tremendous attention of researchers worldwide. Therefore, since its first successful synthesis, a variety of functionalized sumanenes as well as heterosumanenes have been developed because of their unique physiochemical properties. For example, bowl-to-bowl inversion, bowl depth, facial selectivity, crystal packing, metal complexes, intermolecular charge transfer systems, cation-π complexation, electron conductivity, optical properties and so on. Keeping the importance of this beautiful scaffold in mind, we compiled all the synthetic routes available for the construction of sumanene and its heteroatom derivatives including Mehta's first unsuccessful effort up to the latest achievements. Our major goal to write this review article was to provide a quick summary of where the field has been, where it stands at present, and where it might be going in near future. Although several reviews have been published on sumanene chemistry dealing with different aspects but this is the first report that comprehensively describes the 'all-in-one' chemistry of the sumanene architecture since its invention to till date. We feel that this attractive review article will definitely help the scientific community working not only in the area of organic synthesis but also in materials science and technology.

Designing a novel material with considerable nonlinear optical responses based on the bicorannulenyl molecule

In this work, a series of molecules decorated with Li atom and donor/acceptor have been theoretically designed based on bicorannulenyl molecule, where incorporating Li and different substitution are used as an effective strategy for enhancing nonlinear optical response. The mixed method is constructed through incorporating the Li and NO₂/NH₂ substitution. To ensure accuracy, results were compared with another two functionals. As expected, data from three different functional approximations indicate that these molecules have large first hyperpolarizability. The calculation proves that these molecules exhibit large first hyperpolarizability in the range of 1956-37,758 au. For Li doped systems, by analyzing NBO, charge transfer occurs in studied molecules, which helps to get large nonlinear optical response. It is revealed that when Li atom is introduced into the molecule with only NO₂/NH₂ substitution, the first hyperpolarizability increases significantly. Compared with Li doped and NO₂ substitution, incorporating Li and NH₂ substitution can be more powerful in increasing the first hyperpolarizabilities of bicorannulenyl molecule. In addition, the number of NH₂ substitutions can more effectively enhance the first hyperpolarizability. We hope that this study could provide a new idea for designing nonlinear optical materials using bicorannulenyl molecule.

Absorption properties of a BODIPY-curved graphene nanoflake system: A theoretical investigation

Modifications in the electronic transitions of a popular 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (boron dipyrromethene, BODIPY) dye caused by quasi-parallel stacking with corannulene (C) were studied by means of time-dependent density functional theory (TD-DFT) with the CAM-B3LYP functional. The effects of the electron-withdrawing (CN) and electron-donating (NH₂) substituents at the meso (8) position in the BODIPY core and the corannulene rim position on the character, location, and oscillator strengths (f) of some transitions of complexes were also discussed. To understand better the nature of the transitions, their occupied and virtual orbitals involved into the first electronic transitions as well as the electron density difference plots between excited and ground states of the complexes were investigated. The S₀ → S₁ transitions of 8H-B/C and 8NH₂-B/C complexes have a small admixture of the charge transfer (CT) character in direction from BODIPY to corannulene (B → C). They located at 2.80 and 3.11 eV, respectively, and have f of ∼0.15. The 8CN-B/C complex with a stronger acceptor BODIPY part has the S₀ → S₁ transition with a higher degree of CT (B → C) at 2.32 eV with f = 0.08. The 8H-B/2NH₂-C complex with a stronger donor corannulene part has the S₀ → S₁ transition with an expressed CT(B → C)-character at 2.58 eV with f = 0.003, whereas the S₀ → S₂ transition acquires in a some extent the features of the LE(B → B) character. A much interesting situation exists in the case of the 8NH₂-B/2CN-C complex. Here we can find both CT (B → C) and CT (C → B) among the first five states. Besides this, different, higher in energy CT states and states delocalized on both molecules were observed.

Stacked homodimers of substituted contorted hexabenzocoronenes and their complexes with C60 fullerene

Computations show that the tendency of contorted hexabenzocoronene (c-HBC) to form either homodimers or complexes with C₆₀ can be tuned by changing the curvature of the c-HBC via the addition of substituents.