DFT investigation of the interaction between single-walled carbon nanotubes and fluorene-based conjugated oligomers

Recent advances in dithiafulvenyl-functionalized organic conjugated materials

This review highlights the recent studies of advanced organic π-conjugated materials that contain 1,4-dithiafulvene (DTF) as a redox-active component.

Conformational Analysis of the Supramolecular Complexation of Diaryl-Substituted Tetrathiafulvalene Vinylogues with Fullerenes

Tetrathiafulvalene vinylogues (TTFVs) functionalized with diaryl substituents (aryl = 1-napthyl, 9-anthryl, and 1-pyrenyl) via click chemistry have been previously synthesized and studied as tweezer-type receptors for binding with C60 and C70 fullerenes. In particular, dianthryl-TTFV exhibits unique selectivity for C70 fullerene, giving rise to effective fluorescence turn-on sensing of C70 in the presence of a large excess of C60 fullerene. This observation indicated that dianthryl-TTFV has a preferential binding affinity for C70 over C60 fullerene, but the reason for such selectivity is unclear. Aiming at addressing this issue, we herein investigated the relative conformational stability of diaryl-substituted TTFVs in complexation with C70 and C60 fullerenes. The dispersion-corrected density functional theory approximation (B3LYP-D3) was employed in our computational analysis to determine binding energies and electronic properties of these supramolecular complexes. It was found that the highest binding energies (and the lowest relative conformational energies) are in pairings when fullerenes are placed around the central TTFV moieties (such as the triazole rings). The results of electronic properties show that the dianthryl-TTFV and dipyrenyl-TTFV conformers have lower highest occupied molecular orbital-lowest unoccupied molecular orbital gaps relative to the ones obtained for dinaphthyl-TTFV, indicating that dianthryl-TTFV, and to some extend dipyrenyl-TTFV, could be good candidates for chemical sensing of fullerenes with fluorescence spectroscopy. We also investigated the effect of the solvent on the interactions of the diaryl-TTFVs with fullerenes using the polarizable continuum model. In general, the presence of a solvent decreases the diaryl-TTFV/fullerene binding energies, presumably because of the interactions of the solvent with individual fullerenes and diaryl-TTFVs.

The role of the solvent and the size of the nanotube in the non-covalent dispersion of carbon nanotubes with short organic oligomers – a DFT study

Among different dispersants of single-walled carbon nanotubes (SWCNTs), conjugated organic oligomers have the ability to interact strongly with SWCNTs and allow for effective dispersion in several organic solvents. Recently, we have carried out two computational investigations on the intermolecular interactions between conjugated organic oligomers and SWCNTs in order to gain insight into an important process of the non-covalent dispersion of carbon nanotubes with short oligomers. These studies highlighted the fact that two additional factors, namely, the effects of the solvent and the carbon nanotube's size on these interactions need further investigation. In this work, with the help of model compounds (which are molecular fragments of the short oligomers used in our previous investigations), we analyze the significance of these two factors. We employ three dispersion corrected density functional theory (D-DFT) approximations (B97D, wB97XD, and B3LYP-D3) to assess the effect of the DFT method, and two basis sets (6-31G(d) and 6-31++G(d,p)) to assess the importance of using a higher basis set in our computations. The main focus of this work is to assess the effect of solvation and nanotube's size on the structure, electronic properties, and binding energies of the respective pairs of model compounds and segments of carbon nanotubes. No significant differences are found between the results of (6,5) and (8,7) SWCNTs in either the geometrical parameters of interacting oligomers or the general tendency of wrapping of their long side chains (SCs) around the nanotubes. However, we find that the binding energies per atom between nanotubes and model compounds are larger for nanotubes with the smaller diameter. The results of electronic properties also show that all model compounds interact more strongly with the (6,5) SWCNT than with the (8,7) SWCNT. Polar solvents such as chloroform show lower binding energies relative to those obtained without a solvent or with non-polar solvents such as hexane. It appears that the presence of a solvent weakens the oligomer/nanotube interactions and, presumably, strengthens the oligomer/solvent and nanotube/solvent interactions to facilitate dispersion of SWCNTs.

Among different dispersants of single-walled carbon nanotubes (SWCNTs), conjugated organic oligomers have the ability to interact strongly with SWCNTs and allow for effective dispersion in several organic solvents.