We have synthesized three N-monoalkylated DPP (mDPP) derivatives, 3,6-bis(4-chloro-/methyl-/bromo-phenyl)-2-octyl-pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-diones (mDPP-Cl/mDPP-Me/mDPP-Br), by facile one-step monoalkylation of commercially available or easy-prepared corresponding DPP derivatives. All the three compounds have high fluorescence quantum yields (Φ) and exhibit usable two-photon absorption cross-sections (δ = 58–87 GM). They are not only effective one-photon but also more effective two-photon fluorescence chemosensors selectively for fluoride anions. Moreover, the substituents at the benzene ring, even if simple methyl, chloride and bromide, could affect the intramolecular charge transfer from the lactam N to the DPP core, and the sensing performance of mDPP to fluoride ions is in the order, mDPP-Br ≥ mDPP-Cl > mDPP-Me. Proton NMR titrations indicate that the intermolecular proton transfer between the hydrogen atom on the lactam N and the fluoride anion is the sensing origin. The stable chemical structure, small molecular size and usable Φδ in terms of femto-second laser pulses make mDPP moieties suitable for the construction of new and effective fully aromatic two-photon materials applicable in two-photon science and technology.
我们通过对市售或易于制备的相应
DPP 衍
生物进行简单的一步单烷基化反应,合成了三种 N-单烷基化
DPP(m
DPP)衍
生物--3,6-双(4-
氯/甲基/
溴苯基)-2-辛基
吡咯并[3,4-c]
吡咯-1,4(2H,5H)-二酮(m
DPP-Cl/m
DPP-Me/m
DPP-Br)。这三种化合物都具有很高的荧光量子产率(Φ),并表现出可用的双光子吸收截面(δ = 58-87 GM)。它们不仅是有效的单光子荧光
化学传感器,而且还是更有效的选择性
氟阴离子双光子荧光
化学传感器。此外,苯环上的取代基,即使是简单的甲基、
氯化物和
溴化物,也会影响从内酰胺 N 到
DPP 核心的分子内电荷转移,m
DPP 对
氟离子的感应性能顺序为 m
DPP-Br ≥ m
DPP-Cl > m
DPP-Me。质子核磁共振滴定表明,内酰胺 N 上的氢原子与
氟阴离子之间的分子间质子转移是传感的起源。稳定的
化学结构、较小的分子尺寸和飞秒激光脉冲下可用的Φδ,使 m
DPP 分子适合于构建适用于双光子科学和技术的新型有效全芳香双光子材料。