双氰基二苯代乙烯型双光子荧光温度敏感探针

Dicyanostilbene type two-photon fluorescence temperature-sensitive probe

对二甲苯分别经过亲电取代、亲核取代、α-位溴代和亲核取代消除反应得到1,4-二氰基-2-甲基-5-(二乙基磷酰基甲基)苯(Ⅴ);咔唑经过亲核取代反应得到中间体4-(9-咔唑基)-苯甲醛(Ⅶ);中间体Ⅴ与Ⅶ经维蒂希-霍纳尔反应得到目标化合物2,5-二氰基-4-甲基-4′-(9-咔唑基)二苯乙烯(供体-π-受体,D-π-A)(SP),反应总产率达45.5%。SP的溶剂生色范围由412 nm(环己烷)红移至541 nm(二甲基亚砜)(最大发射波长),SP具有非常大的双光子吸收截面(δTPA=6930 GM)和高的荧光量子产率[Φ=0.992(环己烷)],其荧光强度对溶剂极性和温度显示很强的依赖性。在单光子荧光发射(OPE)和双光子荧光发射(TPE)谱图中,SP的单、双光子荧光发射强度与温度之间的线性相关系数(R^(2))均>0.998,表达式分别为IF=–0.0141θ+1.2881(OPE)和IF=–0.0143θ+1.2698(TPE)[IF为荧光强度,θ为温度(℃)]。

Intermediate 1,4-dicyano-2-methyl-5-(diethylphosphomethyl)benzene(Ⅴ)was obtained from paraoxylene through electrophilic substitution,nucleophilic substitution,α-site bromine substitution and nucleophilic substitution elimination,while intermediate 4-(9-carbazole)-benzaldehyde(Ⅶ)was synthesized from nucleophilic substitution of carbazole.Target compound 2,5-dicyano-4-methyl-4′-(9-carbazolyl)stilbene(donor-π-acceptor,D-π-A)(SP)with a total yield of 45.5%was finally synthesized from Wittig-Horner reaction of intermediatesⅤandⅦ.The solvatochromism of SP was redshifted from 412 nm(cyclohexane)to 541 nm(dimethyl sulfoxide)(maximum emission wavelength).Compound SP exhibited remarkably large two-photon absorption cross section(δTPA=6930 GM)and high fluorescence quantum yield(Φ)in cyclohexane,with its fluorescence highly dependent on solvent polarity and temperature.In the one-photon emission(OPE)and two-photon emission(TPE)spectra,the dependent coefficients(R^(2))between single and two-photon emission fluoresence intensity and temperature of SP was>0.998,and the function expressions were IF=–0.0141θ+1.2881(OPE)and IF=–0.0143θ+1.2698(TPE)[IF:fluorescence intensity;θ:temperature(℃)],respectively.