| Among various organic nonlinear optical materials, the small organic molecule is the focus of the research of functional materials. The large organicπ-conjugated system is the key of the relevant molecule design. Benzo[a]phenoxaziniums have been utilized as dyes, medicine, probes for heavy metal ions, fluorescent probes for amino acids and so on. In terms of its structure, since benzo[a]phenoxaziniums have largeπ-conjugation, which allows expecting that they may be used as third-order nonlinear materials. However, to the best of our knowledge, there is few report about the application of benzo[a]phenoxazinium dyes served as nonlinear material. In this article, we present eleven benzo[a]phenoxazine derivatives through a multi-step reaction, and transform one of the dyes into the coresponding salts with different anions. Main conclusions contained two parts as follows.1. Firstly, eleven dyes have been synthesized and their structures have been confirmed by NMR, IR, Mass and element analysis. Then their optical properties including UV-vis, emission spectra were investigated. With the increase the ability of the electron withdrawing group on the benzo[a]phenoxazine dyes, the UV-visual and fluorescence spectra were red-shifted. However, with the change of substituent positions, there is no obvious change about the wavelength of the UV-vis and emission spectra. These compounds have a strong absorption in 532 nm, therefore it is not suitable using Z-scan method of 532 nm laser to study their third-order nonlinear optical properties.2. Secondly, their third-order nonlinear optical properties in acetic acid were studied using the Z-scan technique for one of benzo[a]phenoxazine dyes with different anions. The results reveal that they have strong reverse saturable absorption with the third-order nonlinear optical coefficientsχ(3) equal to 0.421.20×10-11 esu and the second hyperpolarizabilitiesγ' equal to 2.757.29×10-29 esu, respectively. Quantum chemical calculation shows that the compound with more stable highest occupied molecular orbital energy has higher second hyperpolarizability. |
PDF Full Text Request