Research On Synthesis And Photophysical Properties Of Novel Organic Compound With Different Fluorescence Mechanism

In recent years, the rapid development of the fluorescence analysis method isinseparable with its many advantages. Compared with the mass spectrometry, electronprobe and polarography, the equipment of fluorescence analysis is simple and cheap,but it has high detection sensitivity and good selectivity. Therefore, the fluorescentcompounds have a very wide range of applications, such as fluorescent dyes,fluorescent imaging, biological probe, photoluminescence devices and photodynamictherapy, etc. In this paper, we have studied on the synthesis and photophysicalproperties of some novel fluorescent compounds. One class of the compounds are(Z)-3-(quinolin-2-ylmethylene)-3,4-dihydroquinoxalin-2(1H)-one and its tetraphenyl-ethene derivatives. In solution they have no fluorescence but have strong fluorescenceemission in solid. The other class are (Z)-2-(phenanthridin-6(5H)-ylidene)-1-phenyle-thanone-BF2-complex and its derivatives. In solution and solid, these compounds bothhave strong fluorescence emission. The main research contents are as follows:1. We have studied on the synthesis and photophysical properties of the(Z)-3-(quinolin-2-ylmethylene)-3,4-dihydroquinoxalin-2(1H)-one and its tetraphenyl-ethene derivatives.(Z)-3-(quinolin-2-ylmethylene)-3,4-dihydroquinoxalin-2(1H)-onehas the characteristic of the excited state intramolecular proton transfer(ESIPT) andexhibit the aggregation-induced emission (AIE) activity. We also have studied on thederivatives fluorescence properties and found that: compared with the parent, TPEderivatives’ quantum yield is lower, but they exhibit the remarkably enhanced AIEactivity than the parent. On the other hand, the monomer concentration of formingaggregation is decreased, because the TPE is a strong hydrophobic groups. Inaddition, we also found that TPE on the quinoline fragment derivant has a muchstronger emission than TPE on the quinoxaline fragment derivant, this should beattributed to the unique crystallization-induced emission enhancement (CIEE) effect,and TEM test results also proved this point. At last, the quantitative calculationresults indicated that the TPE derivatives also have the characteristic of the ESIPT,but the AIE mechanism have changed from the restriction of twisted intramolecular charge transfer (TICT) to the classic restriction of intramolecular rotation (RIR)effect.2.We have studied on the synthesis and photophysical properties of the(Z)-2-(phenanthridin-6(5H)-ylidene)-1-phenylethanone-BF2-complex and itsderivatives. We have found that all these compounds have good fluorescenceproperties in solution, such as high quantum yield, large molar extinction coefficient,etc. Except for the compound containing dimethyl amine on the phenyl, thesecoplexes all have good fluorescence properties in solid state. We have developed thecrystals of the compounds that contain dimethyl amine or hydrogen atom on thephenyl. The crystal structure analysis showes that: the forfer have formed a spatialnetwork structure in the aggration, it has strong intermolecular interactions, such asπ-π, C-H…π, C-H…F, the excitation energy can dissipation between molecules, sothe solid fluorescence is quenched; The latter have formed isolated two dimmers inthe aggration, and the isolated two dimmers’ intermolecular interactions are weak, sothe solid fluorescence is enhanced. We also introduced the TPE to the different sites ofthe (Z)-2-(phenanthridin-6(5H)-ylidene)-1-phenylethanone-BF2-complex. Thederivatives all have good fluorescence properties. The complex of TPE on the phenylhas the phenomenon of solvent-induced different crystallization, the fluorescenceemission wavelength of the same compound that aggregates from CH2Cl2and THF isdifferent. And the complex of TPE on the phenanthridine has the mechanicalphotochromic property.