Tuning of intramolecular charge transfer properties and charge distributions in ferrocene-appended catechol derivatives by chemical substitution
Tuning of intramolecular charge transfer properties and charge distributions in ferrocene-appended catechol derivatives by chemical substitution
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通过化学取代调节二茂铁邻苯二酚衍生物的分子内电荷转移特性和电荷分布
DOI：
10.1039/c5dt01998b
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发表时间：
2015
影响因子：
4
通讯作者：
Ken Tokunaga
中科院分区：
文献类型：
--
作者：
Keishiro Tahara;Shogo Akehi;Tetsuhiro Akita;Shohei Katao;Jun-ichi Kikuchi;Ken Tokunaga
在这项研究中，我们报道了一系列fcc衍生物(fcc=4-二茂铁儿茶酸盐，其中fc=二茂铁和C=儿茶酸酯)的分子内电荷转移(ICT)性质和电荷分布。该系列化合物包括已报道的FCV(4-二茂铁基藜芦醇)和新合成的FCA(4-二茂铁基邻苯二酚双(乙酸酯)和铂(TBu2bpy)(Fcc)(tBu2bpy=4，4‘-二叔丁基-2，2’-联吡啶))。用循环伏安法对铂(TBu2bpy)(FCC)进行了电化学分析，发现有两个明确的可逆波，分别对应于铂(TBu2bpy)(C)和Fc部分的顺序氧化。两波之间的电势分裂(524 MV)表明两个部分之间存在电子相互作用。通过与[FCV]·+和[FCA]·+(4-二茂铁基邻苯二酚双(醋酸酯))的比较，使[Pt(TBu2bpy)(Fcc)]·+的ICT性质和电荷分布更加合理。密度泛函理论计算和UV-Vis-NIR光谱表明，[Pt(TBu2bpy)(Fcc)]·+、[FCV]·+和[Fca]·+是以二茂铁(Fc+)为中心的，而不是以半醌为中心的，在近红外(NIR)区域，这些配合物具有从邻苯二酚衍生骨架到Fc+部分的ICT跃迁带.电子耦合参数(HAB)和离域参数(α)都随着邻苯二酚骨架上取代基给电子强度的增加而增大(OCOCH3([fca]·+)<；OCH3([fcv]·+)<；O−([tBu2bpy)(Fcc)]·+)。通过改变取代基来调节金属有机中心与非无辜骨架之间的电子相互作用。用二态Marcus-Hush理论得到的FC+衍生物的势能面可以通过改变附加的邻苯二酚衍生物的分子轨道的能级来进行调制。
In this study, we report intramolecular charge transfer (ICT) properties and charge distributions in a series of FcC derivatives (FcC = 4-ferrocenylcatecholate where Fc = ferrocene and C = catecholate). This series consists of a previously reported complex FcV (4-ferrocenylveratrole) and newly synthesized complexes FcA (4-ferrocenylcatechol bis(acetate) and Pt(tBu2bpy)(FcC) (tBu2bpy = 4,4′-di-tert-butyl-2,2′-dipyridyl). An electrochemical analysis of Pt(tBu2bpy)(FcC) using cyclic voltammetry revealed two well-defined, reversible waves which were assigned to the sequential oxidation of the Pt(tBu2bpy)(C) and Fc moieties. The potential splitting between the waves (524 mV) indicated that there was an electronic interaction between both moieties. ICT property and charge distribution of [Pt(tBu2bpy)(FcC)]˙+ were rationalized by comparison with the [FcV]˙+ and [FcA]˙+ (4-ferrocenylcatechol bis(acetate)). DFT calculations and UV-vis-NIR spectroscopy revealed that [Pt(tBu2bpy)(FcC)]˙+, [FcV]˙+, and [FcA]˙+ were ferrocenium (Fc+)-centered rather than semiquinone ligand-centered and that these complexes exhibited ICT transition bands from the catechol-derivatized framework to the Fc+ moiety in the near infrared (NIR) region. Both the electronic coupling parameter (HAB) and delocalization parameter (α) increased in value as the electron-donating strength of the substituent groups in the catechol-derivatized framework increased (OCOCH3 ([FcA]˙+) < OCH3 ([FcV]˙+) < O− ([Pt(tBu2bpy)(FcC)]˙+)). The electronic interactions between the organometallic center and the non-innocent framework were tuned by changing the substituents. The potential energy surfaces of the Fc+ derivatives, obtained using two-state Marcus–Hush theory, can be modulated by changing the energy level of the molecular orbitals of the appended catechol-derivatized moieties.