Loboda O. Quantum-chemical investigation of electronic structure and nonlinear optical properties of porphyrins and fullerene derivatives

The thesis contains a theoretical study of electronic structure, optical and spectroscopic properties of a number of compounds - namely, porphyrins, fullerenes and carbon nanostructures, which include heteroatom single wall nanotubes and others. The milestone of the thesis is to study the nonlinear optical properties and disclose the influence of the nature of substitutes to enhance nonlinear optical effects. Qualitatively new results that address the issue that is of practical importance - namely, the discovery and development of materials for photosensitizers, organic LEDs and solar cells are presented. The performed analysis of a wide range of quantum-chemical methods aimed to study photophysical properties of porphyrin and fullerene derivatives. In particular, as a result of the work it was found the cause and relationship between the overshooted values of polarization components and the donor ability of the substitute. Qualitatively and quantitatively evaluated the electronic and vibrational contributions to the hyperpolarization of fullerene-chromophore donor-acceptor pairs. Single and two-photon absorption spectra of functionalized fullerene derivatives that were calculated on the basis of quantum-chemical calculations agree well with experimental results obtained by MALDI-TOF-MS, ATR-IR, UV, NMR, Z-scan spectroscopies. Particular attention is paid to the design and development of new (O)N linear methods for application in quantum-chemical theory of electronic structure. It was shown that these methods display accuracy comparable to the accuracy of traditional method calculations and greatly reduce the cost of CPU time, which make them an indispensable tool for studying the electronic structure of the nano-compounds.