J Phys Chem B. 2022 Feb 24;126(7):1551-1557. doi: 10.1021/acs.jpcb.1c08598. Epub 2022 Feb 15.
The hydrophobicity of room-temperature ionic liquids (RTILs) has been shown to have a very significant effect on the optical and structural properties of and in RTILs. The average excited state lifetime of neat RTILs has been shown to be increasing with increasing hydrophobicity of the RTILs. By employing pico-nanosecond-based fluorescence anisotropy decay, the volume of the nanoaggregates in neat RTILs have been calculated. The volume of these nanoaggregates have been shown to be decreasing with increase in hydrophobicity of the RTILs. Thus, hydrophobicity has been shown to have an important role, i.e., hydrophobicity can be used as a handle to tune the properties of RTILs as designer solvents. Moreover, the excited-state lifetime of red-emitting fluorophores, i.e., whose fluorescence emission is not perturbed by the inherent emission of RTILs, has been shown to increase with the increasing hydrophobicity of the RTILs. Highly hydrophobic RTILs have been shown to exhibit positive deviation and highly hydrophilic RTIL has been shown to exhibit negative deviation from the linear correlation between average solvation time (τ) versus viscosity/temperature (η/).
室温离子液体 (RTILs) 的疏水性对 RTILs 中的光学和结构性质有非常显著的影响。已证明纯 RTILs 的平均激发态寿命随 RTILs 疏水性的增加而增加。通过采用皮秒纳秒荧光各向异性衰减，可以计算出纯 RTILs 中纳米聚集体的体积。这些纳米聚集体的体积随着 RTILs 疏水性的增加而减小。因此，疏水性被证明具有重要作用，即可以将疏水性用作调节 RTILs 作为设计溶剂的性质的手段。此外，红色发射荧光团的激发态寿命（即其荧光发射不受 RTILs 固有发射的影响）已被证明随 RTILs 疏水性的增加而增加。高疏水性 RTILs 表现出正偏差，而高亲水性 RTIL 则表现出与平均溶剂化时间 (τ) 与粘度/温度 (η/) 之间的线性关系的负偏差。
