Synthesis, Lfuorescence Properties And Biological Activities Of Stilbene Derivatives Containing1,3,4-oxadiazole

Symmetrical and unsymmetrical1,3,4-oxadiazoles are an important class of heterocyclecompounds with broad spectrum of biological activities, which have attracted significantinterest in medicinal and pesticide chemistry for a long time. Derivatives of1,3,4-oxadiazoleshave revealed antibacterial, antifungal, anti-inflammatory, analgesic, anticonvulsant, andinsecticidal activities. Compounds possessing oxadiazole moiety show anticancer, HIV-1integrase inhibitory and tyrosinase inhibitory activities. Stilbene derivatives are well knownfor their considerable biological and medical activities, such as anti-microbial and insecticidaleffects, vasodilation action, and insect baculovirus synergists. In this paper, some novelstilbene derivatives containing1,3,4-oxadiazole were designed and synthesized through thesplicing of the chemical structure-activity group. Besides, we measured the fluorescenceproperties of the products as well as the antibacterial activities. The specific results are asfollows:1. Through the oxidative cyclization reaction of hydrazone by chloramines-T,bromination of N-bromosuccinimide(NBS), esterification and Wittig-Horner reaction, withthe starting material of aromatic aldeyde and4-methylbenzohydrazide, the1,3,4-oxadiazolegroup was introduced into the diphenylethene. Then the structure of the target compoundswere confirmed through the melting point determination, elemental analysis, nuclear magneticresonance, mass spectrometry and the target compounds were23(4a to4w) novel stilbenederivatives containing1,3,4-oxadiazole.2. The performance of the UV-visible and fluorescence spectra were studied, whichinclude maximal UV absorption wavelength, molar extinction coefficient, maximalfluorescence emission wavelength, the relative fluorescence intensity, stokes shift andfluorescence quantum yield Φfof the23stilbene derivatives in the THF solvent. The maximalUV-absorbing wavelength of the compounds are between309-408nm and they possess themaximal single-peak absorption. The fluorescence quantum yield of title compounds whichhave good fluorescence property are between0.7and0.8. In the solvent, the maximumfluorescence emission wavelength of compound4e,4h and4k have a greater red shift relativeto that of the other compounds, which is due to that they possess the longer conjugationlength because of the presence of anthracyclines. The compound4p which contains strongelectron-withdrawing group of-NO2, show the fluorescence quenching in the general polarsolvent.3. Preliminary in vitro antibacterial activity experimen of some intermediates and target compounds have been studied against Staphylococcus aureus and Escherichia coli. Theexperimen results showed that the synthetic stilbene derivatives containing1,3,4-oxadiazolepossessed different antibacterial activities. Relatively, in the concentration of100μg/ml,compound4r possess significant antibacterial activity against S. aureus and E. coli...