Benzoannelated aza-, oxa- and azaoxa[8]circulenes as promising blue organic emitters.

In the present work, we studied the synergetic effect of benzoannelation and NH/O-substitution for enhancing the absorption intensity in a series of novel designed benzoannelated aza- and oxa[8]circulenes. Semi-empirical estimations of the fluorescence rate constants allowed us to determine the most promising fluorophores among all the possible benzoannelated aza-, oxa- and mixed azaoza[8]circulenes. Among them, para-dibenzoannelated [8]circulenes demonstrated the most intense light absorption and emission due to the prevailing role of the linear acene chromophore.

Aromaticity of the doubly charged [8]circulenes.

Magnetically induced current densities and current pathways have been calculated for a series of fully annelated dicationic and dianionic tetraphenylenes, which are also named [8]circulenes. The gauge including magnetically induced current (GIMIC) method has been employed for calculating the current density susceptibilities. The aromatic character and current pathways are deduced from the calculated current density susceptibilities showing that the neutral [8]circulenes have two concentric pathways with aromatic and antiaromatic character, respectively.

Structure and spectroscopic characterization of tetrathia- and tetraselena[8]circulenes as a new class of polyaromatic heterocycles.

The FTIR, Raman and UV-vis spectra of the recently synthesized tetrathia[8]circulene and tetraselena[8]circulene compounds have been measured and interpreted in details by the density functional theory (DFT) calculations taking into account the molecular symmetry constrains. The structural and electronic features of the studied compounds have also been discussed in connection with the observed spectroscopic characteristics. Particularly, we have found that despite a slightly non-planar conformation the neutral tetrathia[8]circulene and tetraselena[8]circulene molecules demonstrate bifacial aromatic/antiaromatic nature.

Aromaticity of the completely annelated tetraphenylenes: NICS and GIMIC characterization.

A series of heterocyclic and hydrocarbon [8]circulenes (also named completely annelated tetraphenylenes) were studied by the NICS and GIMIC methods in order to describe their aromatic properties from the magnetic criterion point of view. According to calculations all the hetero[8]circulene molecules demonstrate the bifacial aromatic/antiaromatic nature. The inner octatetraene core of the studied [8]circulenes is characterized by the presence of paratropic ("antiaromatic") ring currents, whereas the outer macrocycle constructed from the five- and six-membered rings possesses the magnetically-induced diatropic ("aromatic") ring current.

Design of nanoscaled materials based on tetraoxa[8]circulene.

Nanotubes and two-dimensional sheet-like compounds containing tetraoxa[8]circulene core units are theoretically predicted. The large cavities with a diameter of 6 Å in the 2D sheets could be useful for hydrogen storage. The designed compounds are predicted to adsorb strongly in the visible region and to be a promising material for nanophotonics because of their electron-donor properties (p-type semiconductors).