Maity Dinesh, Mardanya Sourav, Karmakar Srikanta, Baitalik Sujoy
Department of Chemistry, Inorganic Chemistry Section, Jadavpur University, Kolkata 700 032, India.
Dalton Trans. 2015 Jun 7;44(21):10048-59. doi: 10.1039/c5dt00708a.
In this work we studied the influence of pH on the absorption, steady state and time-resolved emission spectroscopic behaviors of recently reported multichromophoric trimetallic complexes of the forms (bpy)2M(phen-Hbzim-tpy)M'(tpy-Hbzim-phen)M(bpy)2 (M = Ru(II) or Os(II), and M' = Fe(II), Ru(II), and Os(II)) derived from a heteroditopic phenanthroline-terpyridine bridge, 2-(4-(2,6-di(pyridin-2-yl)pyridine-4-yl)phenyl)-1H-imidazole[4,5-f][1,10]phenanthroline (tpy-Hbzim-phen) and 2,2'-bipyridine (bpy) as the auxiliary ligand. For purposes of comparison, the UV-vis absorption and emission titrations of three monometallic model compounds (bpy)2Ru(phen-Hbzim-tpy)2 (1), [(bpy)2Os(phen-Hbzim-tpy)] (ClO4)2 (2) and (tpy-PhCH3)Ru(tpy-Hbzim-phen)2 (3), where tpy-PhCH3 = 4'-(4-methylphenyl)-2,2':6',2''-terpyridine) were studied under the same experimental conditions. The absorption titration data were used to determine the ground state pKa values, whereas the luminescence and lifetime data were utilized for the determination of excited state pKa* values of the complexes. The evolving factor analyses of the set of absorption spectra of the complexes obtained by varying the pH of the solution confirm that only three absorbing species exist in the pH window of 2-12. Moreover, the modulation of the rate of the intramolecular energy transfer among the components in the homo- and heterotrimetallic complexes as a function of pH of the solution was also demonstrated.
在本工作中，我们研究了pH对最近报道的多发色团三金属配合物吸收、稳态和时间分辨发射光谱行为的影响，这些配合物的形式为(bpy)2M(phen-Hbzim-tpy)M'(tpy-Hbzim-phen)M(bpy)2（M = Ru(II)或Os(II)，且M' = Fe(II)、Ru(II)和Os(II)），其由异双齿菲咯啉-三联吡啶桥、2-(4-(2,6-二(吡啶-2-基)吡啶-4-基)苯基)-1H-咪唑[4,5-f][1,10]菲咯啉（tpy-Hbzim-phen）和2,2'-联吡啶（bpy）作为辅助配体衍生而来。为作比较，在相同实验条件下研究了三种单金属模型化合物(bpy)2Ru(phen-Hbzim-tpy)2（1）、(bpy)2Os(phen-Hbzim-tpy)2（2）和(tpy-PhCH3)Ru(tpy-Hbzim-phen)2（3）的紫外-可见吸收和发射滴定，其中tpy-PhCH3 = 4'-(4-甲基苯基)-2,2':6',2''-三联吡啶。吸收滴定数据用于确定基态pKa值，而发光和寿命数据则用于确定配合物的激发态pKa*值。通过改变溶液pH获得的配合物吸收光谱集的演化因子分析证实，在2-12的pH范围内仅存在三种吸收物种。此外，还证明了同三金属和异三金属配合物中各组分间分子内能量转移速率随溶液pH的变化。
