Institute of Physical Chemistry, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena, Germany.
Phys Chem Chem Phys. 2010 Feb 14;12(6):1357-68. doi: 10.1039/b915770k. Epub 2009 Dec 16.
Ru-dppz (dppz = dipyrido[3,2-a:2',3,3'-c]phenazine) complexes play an important role as environmentally sensitive luminescence sensors and building blocks for larger supramolecular compounds. Their photophysical properties are known to be highly sensitive to intermolecular solvent-solute interactions and solvent bulk-properties. Here, the synthesis and characterisation of a novel Ru-dppz derivative is reported. The potential of drastically tuning the photophysical properties of such complexes is exemplified, by introducing very simple structural modifications, namely bromine, into the dppz-ligand scaffold. The photophysics i.e. nature of excited states and the excited-state relaxation pathway of the various complexes has been investigated by means of electrochemical measurements, steady-state emission experiments and femtosecond time-resolved spectroscopy. It could be shown that the location of bromine substitution influences the relative energy between a luminescent and a non-luminescent metal-to-ligand charge-transfer state and therefore quenches or facilitates transitions between both. Hence it is illustrated that the luminescent properties and the underlying ultrafast excited-state dynamics of the complexes can be controlled by structural variations, i.e. by intramolecular interactions as opposed to changes in the intermolecular interactions.
Ru-dppz（dppz = 二吡咯并[3,2-a:2',3',3”-c]吩嗪）配合物作为对环境敏感的发光传感器和更大超分子化合物的构建块起着重要作用。它们的光物理性质已知对分子间溶剂-溶质相互作用和溶剂整体性质非常敏感。本研究报告了一种新型 Ru-dppz 衍生物的合成和表征。通过在 dppz 配体骨架中引入非常简单的结构修饰，例如溴原子，极大地调节了此类配合物的光物理性质的潜力得到了例证。通过电化学测量、稳态发射实验和飞秒时间分辨光谱学研究了各种配合物的光物理性质，即激发态的性质和激发态弛豫途径。结果表明，溴取代的位置影响发光和非发光金属-配体电荷转移态之间的相对能量，从而猝灭或促进两者之间的跃迁。因此，说明可以通过结构变化，即通过分子内相互作用而不是改变分子间相互作用来控制配合物的发光性质和其超快激发态动力学。
