ИСТИНА

Fullerene acceptors with two or more fullerene cages are of particular interest as prospective n-type semiconducting materials for design of various organic electronic devices. Proximity of fullerene cores, which are binded by tight linkers, provides a large number of close contacts between semiconducting moieties, thus, enhances their intramolecular electronic communication, and, therefore, charge transport properties. However, lack of solubility of multi-caged fullerene derivatives limits their utilization for fabrication of organic electronic devices. Here we report a series of highly soluble double-caged fullerene derivatives, which are tightly bound via pyrrolizidine and cyclobutane rings, with various substituents in the ester function. Novel double-caged fullerene derivatives have been prepared through lithium salt-assisted [2+3]-cycloaddition of azomethine ylides generated from glycine esters and paraformaldehyde. Substituent nature in the ester function plays key role in increasing/decreasing of compounds solubility. Exohedral functionalization through various cycloaddition reactions with double-caged fullerene derivatives has been used for fine-tuning of both electronic properties and solubility. Obtained compounds were characterized by MALDI mass-spectrometry, 1D and 2D NMR spectroscopy, X-ray diffraction analysis. Optical and electronic properties of novel double-caged fullerene derivatives both in solutions and thin films have been studied by UV/Vis-spectroscopy. Cyclic voltammetry studies revealed three closely overlapping pairs of reversible peaks due to consecutive one-electron reductions. Quantum chemical calculations at the DFT level of theory (PBE/TZ2p) were used for optimization of molecule geometry and analysis of frontier molecular orbitals distribution. This work was supported by RFBR (project № 17-03-00488).