Heteroleptic bis-tridentate Fe(II)-NHC complexes as photobases

在文献中已经报道了过渡金属络合物，其在通过UV光直接激发侧链（有机）光酸/光碱基序时或在激发光谱的可见部分中的MLCT跃迁时充当光酸或光碱。然而，几乎没有系统的超快，机制的研究贵金属自由过渡金属络合物的光碱存在。到目前为止，对基于喹啉的光碱性的研究通常集中在分子（全有机）衍生物上。因此，该提案的目的是在合成和机械表征的新的Fe（II）-NHC配合物作为光碱，可以被激活的可见光。设想的研究结合了（i）新复合物的合成和（ii）激发态质子转移（ESPT）反应的高级光谱表征。我们将研究哪些分子内激发态弛豫途径在Fe（II）-NHC络合物为基础的光碱竞争与设想的光碱性。在这个项目中有针对性的深入机制的理解的关键是要了解可能的激发态特定的ESPT反应从溶剂的电子激发的光碱复合物。

Transition metal complexes, acting as photoacids or photobases, either upon direct excitation of a pendant (organic) photoacid / photobase motif by UV light or upon excitation of MLCT transitions in the visible part of the spectrum, have been reported in literature. However, almost no systematic ultrafast, mechanistic studies of noble-metal free transition-metal complex based photobases exist. Up to now, studies on quino¬line-based photobasicity are generally focused on molecular (full-organic) derivatives. Thus, this proposal aims at the synthesis and mechanistic characterization of new Fe(II)-NHC complexes as photobases that can be activated by visible light. The envisioned research combines (i) synthesis of new complexes and (ii) advanced spectroscopic characterization of excited-state proton transfer (ESPT) reactions underlying the photobasic action. We will investigate which intramolecular excited-state relaxation pathways in Fe(II)-NHC complex-based photobases compete with the envisioned photobasicity. Key to the in-depth mechanistic understanding targeted in this project is to understand possible excited-state specific ESPT reactivity from the solvent to the electronically excited photobasic complexes.