Near‐IR Intramolecular Charge Transfer in Strongly Interacting Diphenothiazene‐TCBD and Diphenothiazene‐DCNQ Push‐Pull Triads
Near‐IR Intramolecular Charge Transfer in Strongly Interacting Diphenothiazene‐TCBD and Diphenothiazene‐DCNQ Push‐Pull Triads
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强相互作用联苯并噻嗪 – TCBD 和联苯并噻嗪 – DCNQ 推 – 拉三元组中的近红外分子内电荷转移
DOI：
10.1002/chem.202200348
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
D'Souza, Francis
中科院分区：
文献类型：
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作者：
Yadav, Indresh S.;Jang, Youngwoo;Rout, Yogajivan;Thomas, Michael B.;Misra, Rajneesh;D'Souza, Francis
通过铜离子介导的埃格林顿偶联反应和钯催化的Sonogashira偶联反应，合成了三种类型的吩噻嗪二聚体（PTZ-PTZ，1-3），它们通过一个或两个乙炔连接基共价连接，产率很高。二聚体1 - 3进一步与强电子受体四氰基乙烯（TCNE）和7，7，8，8-四氰基醌二甲烷（TCNQ）进行[2+2]环加成-逆电环化反应，分别产生四氰基丁二烯（TCBD，1 a-3 a）和二氰基醌二甲烷（DCNQ，1 B-3 B）官能化的供体-受体（D-A）缀合物。通过一系列光谱、计算和电化学研究来检查缀合物。在这两个系列的D-A共轭物中都观察到了导致新的光学跃迁的强基态极化。在DCNQ衍生的D-A系统1 B的情况下，光学覆盖范围在苯甲腈中延伸至1200 nm，使其成为一类罕见的D-A ICT系统。 在这些D-A体系中观察到了多个氧化还原过程，DFT优化结构上产生的前线轨道进一步支持了ICT现象。使用飞秒泵浦-探测研究进行的光化学研究证实了这些新型多模块D-A缀合物中的溶剂极性依赖性激发态电荷转移和分离。电荷分离态在苯甲腈中持续高达70 ps，而在甲苯中略微延长的寿命高达100 ps。 吩噻嗪二聚体在宽带光学捕获中的意义一直到近红外区域，并促进D-A-D配置的多模块系统中的超快光诱导电荷转移，以及供体-受体距离和溶剂极性的影响是本研究的直接结果。
Three types of phenothiazines dimers (PTZ‐PTZ,1–3), covalently linked with one or two acetylene linkers, were synthesized by copper‐mediated Eglinton and Pd‐catalyzed Sonogashira coupling reactions in excellent yields. The dimers1–3were further engaged in [2+2] cycloaddition‐retroelectrocyclization reactions with strong electron acceptors, tetracyanoethylene (TCNE) and 7,7,8,8‐tetracyanoquinodimethane (TCNQ) to yield tetracyanobutadiene (TCBD,1 a–3 a), and dicyanoquinodimethane (DCNQ,1 b–3 b) functionalized donor‐acceptor (D‐A) conjugates, respectively. The conjugates were examined by a series of spectral, computational, and electrochemical studies. Strong ground state polarization leading to new optical transitions was witnessed in both series of D‐A conjugates. In the case of DCNQ derived D‐A system1 b, the optical coverage extended until 1200 nm in benzonitrile, making this a rare class of D‐A ICT system. Multiple redox processes were witnessed in these D‐A systems, and the frontier orbitals generated on DFT optimized structures further supported the ICT phenomenon. Photochemical studies performed using femtosecond pump‐probe studies confirmed solvent polarity dependent excited state charge transfer and separation in these novel multi‐modular D‐A conjugates. The charge‐separated states lasted up to 70 ps in benzonitrile while in toluene slightly prolonged lifetime of up to 100 ps was witnessed. The significance of phenothiazine dimer in wide‐band optical capture all the way into the near‐IR region and promoting ultrafast photoinduced charge transfer in the D‐A‐D configured multi‐modular systems, and the effect of donor‐acceptor distance and the solvent polarity was the direct outcome of the present study.