Synthesis Of Organic Compounds With π -electron Conjugate Plane And Research On Its Optical Properties

Since the invention of the first laser in 1960s, nonlinear optics has been developed into a new discipline and widely developed and applied in many fields. With the deep investigation of theory and application, people had a certain understanding at the essence of the nonlinear phenomenon. New nonlinear optics materials with special function have been turned into study goals. In 1964s, the nonlinear effect of organic compound was first discovered. It has opened a new area for nonlinear optical materials studying. The optical materials with large three-photon absorption(3PA)cross section have been found to be useful for a variety of applications such as multiphoton fluorescence imaging, up–converted stimulated emission, optical limiting and light-activated therapy. So, to look for and synthesize the organic materials becomes the hot issue. We designed and synthesized a new fluorene compound and a carbazole compound based on fluorene and carbazole as conjugated cores, which have good rigidity and planarity. Their linear absorption, fluorescence and optical limiting are systematically investigated. The influence of the solvents, temperature and concentration on fluorescence properties was also studied.The principal work in this paper mainly divided into the following five aspects:Firstly, a new fluorene compound and a carbazole compound were synthesized by the Heck reaction and N-alkylation reaction. The structures were characterized and analysis with Infrared (Ir), Nuclear magnetic resonance (NMR) spectra and mass spectrometry. Results showed that the products are the target compounds.Secondly, the fluorescence emissions were observed by fluorescence spectrometry. The results showed the compounds had strong ability of fluorescence emission in blue area 350~550nm.Thirdly, solvent polarity had certain effect on fluorescence spectra and uv absorption spectra of the two compounds. The influence of temperature and solution concentration on fluorescence was also investigated. For the carbazole compound, the influence of anionic surfactants on fluorescence spectra was tested, founding that when the concentrations reached its micelle concentration, the fluorescence intensity was 40 times more than without surfactants.Fourth, the structure of fluorene compound was optimized using Gaussian 03 software. The excited state and highest occupied molecular orbital and the lowest unoccupied molecular orbital of the compound were calculated. The electronic transition and intra-molecular charge transfer were explained in theory.Fifth, picoseconds laser was used to investigate the optical limiting of the two compounds. The optical limiting effect was due to the absorbed threephotons at the same time. Their 3PA coefficients and 3PA cross sections are obtained by fitting the optical limiting data.