Bodapati Ramakrishna, Sahoo Chakradhar, Gudem Mahesh, Das Samar K
School of Chemistry , University of Hyderabad , Central University P.O. , Hyderabad 500 046 , Telangana , India.
School of Physics , University of Hyderabad , Central University P.O. , Hyderabad 500046 , Telangana , India.
Inorg Chem. 2019 Sep 3;58(17):11470-11479. doi: 10.1021/acs.inorgchem.9b01235. Epub 2019 Aug 20.
By using monosubstituted 2,2'-bipyridine asymmetric ancillary ligands with different electron donor moieties and an arene ligand (-cymene), we successfully designed and synthesized six Ru(II) compounds () that belong to a piano-stool-type system. The NLO properties of the synthesized complexes have been studied in both solution and the solid state. The electronic spectra of these compounds show a broad feature with two absorption bands in the visible window (350-650 nm). complexes exhibit NIR emission spectra in the solution state (at >720 nm), the maxima of which are bathochromically shifted in comparison to those of the concerned ligands. Interestingly, compounds show NIR emission in their solid state too. Title compounds have lifetimes in the range of 0.2 to 0.9 ns. An important feature of this work is the π-association of the -cymene ligand to Ru(II) in the synthesized complexes; the π complex is formed by breaking the symmetry of -cymene, found in the starting precursor (Ru dimer). This has been established by NMR spectral studies along with DFT calculations on the H NMR spectra. We could derive the molecular structure of the cationic part of this system by density functional theory (DFT), associated with H NMR spectral studies. The minimum energy structures for and have been optimized at DFT/B3LYP along with the LANL2DZ basis set for ruthenium atoms. These optimized structures are further considered to calculate the excited state properties using the TDDFT method. The electrochemical studies of the complexes, investigated in acetonitrile solution, show that this system is associated with a well-defined Ru(III)/Ru(II) reversible couple, rarely observed for a Ru(II) piano-stool-type compound, along with a feature of irreversible ligand oxidation. The absorption cross-section values, obtained from the two-photon absorption studies of title compounds , are worth reporting and lie in the range of 3-28 GM (in the femtosecond case).
通过使用带有不同供电子基团的单取代2,2'-联吡啶不对称辅助配体和一个芳烃配体（对异丙基苯），我们成功设计并合成了六种属于钢琴凳型体系的Ru(II)化合物（）。已在溶液和固态中研究了合成配合物的非线性光学性质。这些化合物的电子光谱在可见光窗口（350 - 650 nm）呈现出具有两个吸收带的宽谱特征。配合物在溶液状态下（>720 nm）呈现近红外发射光谱，其最大值相对于相关配体发生了红移。有趣的是，化合物在固态下也呈现近红外发射。标题化合物的寿命在0.2至0.9 ns范围内。这项工作的一个重要特征是在合成配合物中对异丙基苯配体与Ru(II)的π缔合；π配合物是通过打破起始前体（Ru二聚体）中对异丙基苯的对称性形成的。这已通过核磁共振光谱研究以及对氢核磁共振光谱的密度泛函理论计算得以证实。我们可以通过密度泛函理论（DFT）结合氢核磁共振光谱研究推导该体系阳离子部分的分子结构。已使用DFT/B3LYP方法并结合钌原子的LANL2DZ基组对和的最低能量结构进行了优化。这些优化结构进一步用于使用含时密度泛函理论（TDDFT）方法计算激发态性质。在乙腈溶液中对配合物进行的电化学研究表明，该体系与一个明确的Ru(III)/Ru(II)可逆偶合相关，这在Ru(II)钢琴凳型化合物中很少见，同时还具有不可逆配体氧化的特征。从标题化合物的双光子吸收研究中获得的吸收截面值值得报道，其范围在3 - 28 GM（飞秒情况）。
