Cubane and cubanoid: Structural, optoelectronic and thermodynamic properties from DFT and TD-DFT method

Tetraasteranes as homologues of cubanes: effective scaffolds for drug discovery

Classical hydrocarbon scaffolds have long assisted in bringing new molecules to the market for a variety of applications, but one notable omission is that of tetraasteranes, which are homologues of cubanes belonging to a class of polycyclic hydrocarbon cage compounds. Tetraasteranes exhibit potential as scaffolds in drug discovery due to their identical cyclobutane structures and rigid conformation resembling cubanes. Based on the studies of the physical and chemical properties of tetraasteranes by density functional theory, three series of compounds were designed as homologues of cubanes by the substitution of cubane scaffolds in pharmaceuticals with tetraasteranes. Their potential for pharmaceutical applications was evaluated in silico by molecular docking and dynamics simulations. Their pharmacokinetic and physicochemical properties were studied by the ADMET (absorption, distribution, metabolism, excretion, and toxicity) analysis. The results indicate that tetraasteranes may be scaffolds as novel bioisosteres of cubanes, as well as hydrogen bond donors or acceptors, which enhance the affinity between ligands and receptors with more stable binding behavior and feasible tolerability in ADMET. All these findings provide new opportunities for tetraasteranes to serve as effective pharmaceutical scaffolds for drug discovery and to accelerate the drug discovery process by repurposing both new and old commercial compounds.

Mechanical Properties of Cubene Crystals

The fullerene family, whose most popular members are the spherical C60 and C70 molecules, has recently added a new member, the cube-shaped carbon molecule C8 called a cubene. A molecular crystal based on fullerenes is called fullerite. In this work, based on relaxational molecular dynamics, two fullerites based on cubenes are described for the first time, one of which belongs to the cubic system, and the other to the triclinic system. Potential energy per atom, elastic constants, and mechanical stress components are calculated as functions of lattice strain. It has been established that the cubic cubene crystal is metastable, while the triclinic crystal is presumably the crystalline phase in the ground state (the potential energies per atom for these two structures are -0.0452 and -0.0480 eV, respectively).The cubic phase has a lower density than the monoclinic one (volumes per cubene are 101 and 97.7 Å3). The elastic constants for the monoclinic phase are approximately 4% higher than those for the cubic phase. The presented results are the first step in studying the physical and mechanical properties of C8 fullerite, which may have potential for hydrogen storage and other applications. In the future, the influence of temperature on the properties of cubenes will be analyzed.

Bond order effects on the optoelectronic properties of oxygen/sulfur functionalized adamantanes

The objective of this work, is to study adamantanes and to tune their bandgap, since pure adamantane is considered as an insulator due to its high bandgap energy. For this, we doped adamantane with oxygen and sulfur atoms, thus obtaining 730 different structures with double bonds and 730 different structures with single bonds, for a total of 1460 structures, and compared their properties. Among all, 31 molecules were selected that best represented the reduced bandgap behavior. The calculations with greater precision in its results were made using the Local Density Approximation (LDA), in the Density-Functional Theory (DFT) formalism, with PWC functional and TNP basis set. The electronic and optical properties were analyzed, by calculating the energy gap and absorption spectrum. Importantly, we observed that molecules doped with sulfur atoms (double bonds) had their energy gap reduced significantly compared to molecules doped with sulfur and/or oxygen atom with single bonds and pristine adamantane. It was found that in the absorption spectrum, the sulfur-doped structures had their spectrum shifted to the visible region, a fact that becomes relevant for potential dyes and optoelectronic applications. From the seven selected functionalized adamantanes (ADD-04, ADD-05, ADD-07, ADD-19, ADD-20, ADD-41, and ADD-48), any of these could be used as a dye. However, the ADD-20 molecule in particular, which presented optical absorption near (RGB) primary colors, could indicate a potential quantum dot material for application in developing screens of various electronic devices.