Synthesis, Self-assembly And Optical Propetries Of Intramolecular Charge-transfer Compounds

With the centralization of functions and miniaturization of devices, the coredifficulty in researches has gradually focused on the nature of materials. Due to thewell-defined morphologies, easy modifiability and structure-dependent properties,organic materials usually own novel properties and have broad application prospects.Intramolecular charge transfer (ICT) compounds, one important member of it, havemany applications in, for example, dye-sensitized solar cells, sensors, informationstorage and nonlinear materials. It is favorable to tune the efficiency of charge transferprocess in molecules by adjusting the donors、π-conjugated bridge or acceptors whichwould in turn has significant effect on their properties.Our whole work is based on the topic of ICT and synthesized four different ICTcompounds. These compounds were used to fabricate well-formedmicro-/nano-structures with the help of intermolecular forces such as hydrogen bond,π-π stacking, and dipole-dipole interaction. Then the optical properties of thesewell-defined self-assemblies were also investigated.Chapter One is the introduction to backgrounds, including the driving force ofself-assembly and methods to obtain these supramolecular structures as well as the applications of ICT compounds.In Chapter Two, we used the cyano group as the acceptor and furan or methoxygroup as the donors, through changing the strength of donors, we synthesized two ICTcompounds. With the investigation of single-crystal structures, it is revealed that thecompounds have different space stacking styles and intermolecular forces. They couldself-assemble into various morphologies such as wire-, tube-, rod-and cube-likedstructures by virtue of solvent evaporation method. At last, the nonlinear opticalproperties of two kinds of well-defined microcrystals were tested. It is showed thatboth are good third order nonlinear optical materials and their fluorescence intensity ispolarization-dependent which has large polarization ratio.In Chapter Three, carbazole and perylene were used as the donor and acceptorrespectively (two molecules). The symmetry of molecules and the strength of thedipole-dipole interaction were changed by tuning the number of carbazoles onperylene. Then we investigated the effect of dipole-dipole interaction onself-assembly behavior systematically. It is indicated that there were differences of thetwo molecules both in morphologies and spectra. For one molecule, changing thegrowth rate of self-assembly can also obtain various structures which make it possibleto tune the supramolecular assemblies from zero dimensions to one dimension even totwo dimensions. By comparing the photophysical properties of these assemblies, it isrevealed that the property of organic nanomaterials is not only related to molecularstructures, but also has relationships with the mode of molecular stacking.Chapter Four summarized the main research results obtained in this dissertation.