FRET-based probe for fluoride based on a phosphorescent iridium(iii) complex containing triarylboron groups
作者:Wenjuan Xu、Shujuan Liu、Huibin Sun、Xinyan Zhao、Qiang Zhao、Shi Sun、Shan Cheng、Tingchun Ma、Lixia Zhou、Wei Huang
DOI:10.1039/c1jm00071c
日期:——
An excellent F−probe (complex 1) based on carbazole-fluorene-carbazole (CzFCz) as a fluorescent donor and a cationic Ir(III) complex unit containing dimesitylboryl (Mes2B) groups as a phosphorescent acceptor has been designed and synthesized. Several reference compounds, such as complex 2 which is similar to complex 1 but without Mes2B groups, fluorescent donor CzFCz, and phosphorescent acceptors A1 and A2, were also synthesized in order to better understand the influence of Mes2B groups on the excited state properties and fluorescence resonance energy transfer (FRET) in this system. The introduction of Mes2B groups on the ligands of the Ir(III) complex unit can lead to a red-shifted and more intense absorption, facilitating efficient FRET from the fluorescent donor to the phosphorescent acceptor. Complex 1 displayed highly efficient orange-red phosphorescent emission with an emission peak at 584 nm in CH2Cl2 solution at room temperature. The emission wavelength of complex 1 in film is red-shifted to 600 nm with a shoulder at 650 nm, and its quantum efficiency in film was measured to be 0.15 under excitation at 450 nm. Utilizing the specific Lewis acid–base interactions between boron atom and F−, the binding of F− to complex 1 can change its excited state and suppress FRET, quenching the phosphorescent emission from the Ir(III) complex and enhancing the fluorescent emission from CzFCz. Thus, a visual change in the emission color from orange-red to blue was observed. Optical responses of complex 1 to F− revealed that it can be used as a highly selective, colorimetric and ratiometric optical probe for F− utilizing the switchable phosphorescence and fluorescence.
基于咔唑-芴-咔唑(CzFCz)作为荧光供体和一个含有二甲基硼(Mes2B)基团的阳离子铱(III)配合物单元作为磷光受体,设计并合成了一种优秀的F-探针(复合物1)。为了更好地理解Mes2B基团对激发态性质和荧光共振能量转移(FRET)的影响,还合成了几种参考化合物,如与复合物1相似但不含有Mes2B基团的复合物2,荧光供体CzFCz以及磷光受体A1和A2。在铱(III)配合物单元的配体上引入Mes2B基团可以导致吸收红移并增强,从而促进从荧光供体到磷光受体的有效FRET。复合物1在室温CH2Cl2溶液中显示出高效的橙红色磷光发射,发射峰为584 nm。复合物1在薄膜中的发射波长红移至600 nm,并伴有650 nm的肩峰,在450 nm激发下测得其薄膜中的量子效率为0.15。利用硼原子和F-之间的特定Lewis酸碱相互作用,F-与复合物1的结合可以改变其激发态并抑制FRET,从而抑制铱(III)配合物的磷光发射并增强CzFCz的荧光发射。因此,观察到发射颜色的视觉变化,从橙红色变为蓝色。复合物1对F-的光学响应表明,它可以作为F-的高选择性、比色和比率光学探针,利用可切换的磷光和荧光。