| Materials with two-photon absorption properties have potential application value in two-photon fluorescence microscopy and imaging, optical micro-machining, there-dimensional optical information storage. Therefore,synthesis of optical materials with large two-photon absorption cross-section has been a research hotspot. Through reading literature, we understand that the multi-branched compounds could increase the two-photon absorption cross-section caused by synergizing which is caused by the electronic coupling between the side chains .In this paper, we synthesized two types of fluorescent compounds and tested their optical properties.One, we synthesize the pyrazine derivatives and study the two-photon absorption properties.the three compounds were synthesize firstly, the compouds are 2,5-bis(4-fluorostyryl)-3,6-dimethylpyrazine,2,5-dimethyl-3,6-bis((E)-2-(thiophen-2-yl)vinyl)pyrazine and 2,5-bis((E)-2-(furan-2-yl)vinyl)-3,6-dimethylpyrazine. Major work and conclusions are as follows:1,The compounds were synthesized firstly by using 2,3,4,5-tetramethy-pyrazine which occurs Knoevenagel reaction with aldehyde. The molecular structure in the ground state of three compounds was optimized by PM3 semi-empirical method, the charge density and the electron cloud density of the frontier molecular orbitals were also calculated. The results show that, the charge is transferred from the electron donors to the pyrazine acceptor.2,The luminescence properties of the compounds in various solvents and having different electron donor were studied. With the increase of solvent polarinty, solvents have little impact on the absorption spectra. But SPEF is effected largely by the polarity of solvents, the emission wavelength with increasing solvent polarity appear red-shift, and the fluorescence quantum yield also decrease with increase of solvent polarity, showing positive solvatokinetic effect.Absorption wavelength appear red-shift with increasing donor ability, showing that the donor ability of the group is stronger, the charge transfer is more easy. Which makes the orbital energy decrease between HOMO and LUMO, as a result the wavelength red-shift.3,In this paper, we describe in details the calculation and test method of two-photon absorption cross-section, Through experimental data,we verifed the rationality of two-photon absorption mechanism. Otherside, we compared the differences between SPEF and TPEF, as well as the effect of the solvents. Emission wavelength of TPEF appear small red-shift with increasing donor ability, about 5nm, Which is similar to SPEF. This indicate that the SPEF and TPEF luminescence mechanism in some ways is similar. The emission wavelength of TPEF appear more obviously red-shift than that of SPEF. This is mainly due to the effects of re-absorption.Second, the synthesis and aggregate state fluorescence study of barbituric acid derivatives were carried out. Because the fluorescence emission intensity of traditional organic materials in dilute solution is high, but in solid state, the fluorescence quenched due to molecular aggregation. This is negative for the production of organic device. Whereas aggregation-induced emission compounds can avoid such abuse. Therefore, this paper is aim to systhesize this sort of compounds.5-(4-(9H-carbazol-9-yl)benzylidene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione was chosen to study as the main object.. And it was confirmed that the compounds had aggregation-induced emission through experiment. The fluorescence spectroscopy was tested in solution and solid. While, mixing the compound and acrylate to prepare the film, the fluorescence intensity incresed. The cause of aggregation-induced emission was speculated. Otherwise, the molecular structure was optimized by PM3 semi-empirical method, the electron cloud density of the frontier molecular orbitals were also calculated. We proved the rationality of our speculation on the other hand by this.
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