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Abstract：
Two heteroleptic NiII complexes combined the redox-active catecholate and 2,2\'- bipyridine ligand platforms were synthesized to observe a photoinduced intramolecular ligand-to-ligand charge transfer (LL\'CT, HOMOcatecholate → LUMOα-diimine). A molecular design of compound [NiII(3,6-Cat)(bipy)]∙CH3CN (1) on the base of bulky 3,6-di-tert-butyl-o-benzoquinone (3,6-DTBQ) was an annelation of the ligand with an electron donor glycol fragment, producing derivative [NiII(3,6-Catgly)(bipy)]∙CH2Cl2 (2), in order to influence the energy of LL\'CT transition. A substantial longwave shift of the absorption peak was observed in the UV-Vis-NIR spectra of 2 compared with those in 1. In addition, the studied NiII derivatives demonstrated a pronounced negative solvatochromism, which was established using a broad set of solvents. The molecular geometry of both compounds can be ascribed as an insignificantly distorted square-planar type, and the π-π intermolecular stacking of the neighboring α-diimines is realized in a crystal packing. There is a lamellar crystal structure for complex 1, whereas the perpendicular T-motifs with the inter-stacks attractive π-π interactions form the packing of complex 2. The redox-active nature of ligand systems was clearly shown through the electrochemical study: a quasi-reversible one-electron reduction of 2,2\'-bipyridine and two reversible successive one-electron oxidative conversations (\"catecholate dianion-o-benzosemiquinonato radical anion-neutral o-benzoquinone\") were detected.
摘要：
合成了两个结合了氧化还原活性儿茶酚盐和2,2'-联吡啶配体平台的杂配NiII配合物，以观察光诱导的分子内配体到配体的电荷转移（LL'CT，同儿茶酚→LUMOα-二亚胺）。基于庞大的3,6-二叔丁基-邻苯醌（3,6-DTBQ）的化合物[NiII（3,6-Cat）（bipy）]·CH3CN（1）的分子设计是配体与电子供体二醇片段，产生衍生物[NiII(3,6-Catgly)(bipy)]·CH2Cl2(2)，以影响LL\'CT跃迁的能量。与1相比，在2的UV-Vis-NIR光谱中观察到吸收峰的大量长波偏移。此外,研究的NiII衍生物表现出明显的负溶剂化变色，这是使用广泛的溶剂建立的。两种化合物的分子几何形状都可以归因于不明显扭曲的方形平面类型，并且在晶体堆积中实现了相邻α-二亚胺的π-π分子间堆叠。络合物1具有层状晶体结构，而具有堆叠间吸引π-π相互作用的垂直T基序形成络合物2的堆积。通过电化学研究清楚地显示了配体系统的氧化还原活性性质：2,2'-联吡啶的准可逆单电子还原和两个可逆的连续单电子氧化对话（“儿茶酚酸二阴离子-邻苯并半醌自由基阴离子-中性邻苯醌”）被检测到。
