Dynamic neighbouring participation of nitrogen lone pairs on the chromogenic behaviour of trans-bis(salicylaldiminato)Pt(ii) coordination platforms
Dynamic neighbouring participation of nitrogen lone pairs on the chromogenic behaviour of trans-bis(salicylaldiminato)Pt(ii) coordination platforms
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氮孤对动态邻近参与反式双(水杨醛基)Pt(ii)配位平台的显色行为
DOI：
10.1039/c6dt04005e
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Takeshi Naota
中科院分区：
文献类型：
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作者：
Takumi Hashimoto;Kanako Fukumoto;Ngoc Ha-Thu Le;Tatsuya Matsuoka;Soichiro Kawamorita;Naruyoshi Komiya;Takeshi Naota
使用新设计的带有水杨醛腙配体的 Pt 类似物，检查了邻近氮孤对对反式双（水杨醛亚胺）Pt（II）平台显色控制的参与。合成了一系列以水杨醛腙作为反式配位二齿配体的非拱形和拱形 Pt 配合物 (1-5)，并针对反式双(水杨醛亚胺)Pt(II) 配位平台的显色行为进行了表征。 X射线衍射和2D NMR数据表明，在非拱形N-单甲基配合物1的情况下，由于分子内氢键产生的构象固定，邻近的N(2)孤对电子对反式双(水杨醛二胺)Pt(II)平台的d-π共轭有显着的参与。相比之下，N,N-二甲基类似物 2 的孤对电子由于构象迁移率高，对 d-π 共轭延伸的贡献要小得多。配合物 1-5 被发现在溶液状态下具有结构依赖性显色特性，使得 N-甲基、短拱形配合物 1 和 3 的吸收光谱相对于 N,N-二甲基、长拱形类似物 2 和 5 表现出显着的减色位移，后者的光谱与反式双（水杨醛亚胺）Pt(II) 配合物 6 的光谱非常相似。 1和2的芳环上的3-和5位分别引起显着的红移和红移。此外，各种溶剂的νmax - ET(30)图显示，配合物1-5表现出负溶剂化显色现象，其中在酒精溶剂中获得的数据与1和3的非酒精溶剂中获得的数据深色分离，这种效应在2和5中没有观察到。配合物1-5在二甲亚砜中添加过量的CH3SO3H后也表现出发射增强，并且连接基对量子效率有显着影响。在拱形复合体的情况下观察到了产量（Φ77 K）。密度泛函理论计算（B3LYP/6-31G*，LanL2DZ）确定这些非拱形和多亚甲基拱形腙配合物的显色行为的结构依赖性可归因于反式双（水杨醛亚胺）Pt（II）配位平台上的d-π共轭中相邻氮孤对的参与变化。
The participation of neighbouring nitrogen lone pairs in the chromogenic control of trans-bis(salicylaldiminato)Pt(II) platforms was examined, using newly designed Pt analogues bearing salicylaldehyde hydrazone ligands. A series of non-vaulted and vaulted Pt complexes (1–5) with salicylaldehyde hydrazones as trans-coordinated bidentate ligands were synthesized and characterized with regard to the chromogenic behaviour of the trans-bis(salicylaldiminato)Pt(II) coordination platforms. X-ray diffraction and 2D NMR data demonstrated that, in the case of the non-vaulted N-monomethyl complexes 1, there was significant participation of neighbouring N(2) lone pairs in the d–π conjugation of the trans-bis(salicylaldiminato)Pt(II) platforms owing to conformational fixation arising from intramolecular hydrogen bonding. In contrast, the lone pairs of the N,N-dimethyl analogues 2 made a much less significant contribution to the extension of the d–π conjugation, due to their high conformational mobility. Complexes 1–5 were found to have structure-dependent chromogenic properties in the solution state, such that the absorption spectra of the N-methyl, short-vaulted complexes 1 and 3 exhibited significant hypsochromic shifts relative to the N,N-dimethyl, long-vaulted analogues 2 and 5, which had spectra very similar to that of the trans-bis(salicylaldiminato)Pt(II) complex 6. The introduction of MeO groups at the 3- and 5 positions on the aromatic rings of 1 and 2 gave rise to significant hypsochromic and bathochromic shifts, respectively. In addition, νmax − ET(30) plots for various solvents revealed that complexes 1–5 exhibit negative solvatochromism, in which the data obtained in alcoholic solvents are hypsochromically separated from those in non-alcoholic solvents for 1 and 3, an effect that is not observed for 2 and 5. Complexes 1–5 also exhibit emission enhancement upon addition of excess CH3SO3H in dimethyl sulfoxide, and a significant effect of the linker on quantum yields (Φ77 K) was observed in the case of the vaulted complexes. Density functional theory calculations (B3LYP/6-31G*, LanL2DZ) determined that the structure dependence of the chromogenic behaviour of these non-vaulted and polymethylene-vaulted hydrazone complexes can be attributed to variations in the participation of neighbouring nitrogen lone pairs in the d–π conjugation on the trans-bis(salicylaldiminato)Pt(II) coordination platforms.