Rhodamine-Platinum Diimine Dithiolate Complex Dyads as Efficient and Robust Photosensitizers for Light-Driven Aqueous Proton Reduction to Hydrogen
Rhodamine-Platinum Diimine Dithiolate Complex Dyads as Efficient and Robust Photosensitizers for Light-Driven Aqueous Proton Reduction to Hydrogen
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DOI：
10.1021/jacs.7b11581
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发表时间：
2018-02-21
影响因子：
15
通讯作者：
Eisenberg, Richard
中科院分区：
文献类型：
--
作者：
Li, Guocan;Mark, Michael F.;Eisenberg, Richard
合成了三种新的二联体，由罗丹明（RDM）染料共价连接到铂二亚胺二硫纶（PtN 2S 2）电荷转移络合物，并用作光敏剂从水溶液质子产生H-2。这三个二联体的不同之处仅在于罗丹明氨基上的取代基，并表示为Pt-RDM 1、PtRDM 2和Pt-RDM 3。在乙腈中，这三个二联体在可见光区显示出强吸收，对应于罗丹明π-π * 吸收以及混合金属-二硫代硫醇盐-二亚胺电荷转移带特征的PtN 2S 2配合物。从Pt-RDM 1到Pt-RDM 3的罗丹明π-π * 吸收最大值的位移与电化学实验中测量的HOMO-LUMO能隙很好地相关。在白色光照射下，当连接到镀铂的TiO 2纳米颗粒（Pt-TiO 2）时，二联体显示出高的和稳健的H-2生成活性。经过40小时的照射后，含有Pt-RDM 1，Pt-RDM 2和Pt-RDM 3的系统分别表现出33600，42800和70700的转换数（TON）。超快瞬态吸收光谱表明，从罗丹明（1）π π * 状态的单重态电荷转移（（CT）-C-1）状态的PtN 2S 2的发色团的能量转移发生在1 ps的所有三个二进制。从若丹明（1）π-π * 态到电荷分离（CS）RDM（0.）Pt（+.）国家也在观察。使用RDM-PtN 2S 2二联体产生H-2的系统的相对活性的差异与用于产生H-2的CS状态和（PtNS 2）-S-2（CT）-C-3状态的相对能量很好地相关。这些研究结果表明，如何可以微调的激发态能级直接激发态人口的光化学生产状态，并突出了明智的设计的光敏剂二分体的光吸收和光诱导的电子转移的光生成H-2从水溶液的质子的重要性。
Three new dyads consisting of a rhodamine (RDM) dye linked covalently to a Pt diimine dithiolate (PtN2S2) charge transfer complex were synthesized and used as photosensitizers for the generation of H-2 from aqueous protons. The three dyads differ only in the substituents on the rhodamine amino groups, and are denoted as Pt-RDM1, PtRDM2, and Pt-RDM3. In acetonitrile, the three dyads show a strong absorption in the visible region corresponding to the rhodamine pi-pi* absorption as well as a mixed metal-dithiolate-to-diimine charge transfer band characteristic of PtN2S2 complexes. The shift of the rhodamine pi-pi* absorption maxima in going from Pt-RDM1 to Pt-RDM3 correlates well with the HOMO-LUMO energy gap measured in electrochemical experiments. Under white light irradiation, the dyads display both high and robust activity for H-2 generation when attached to platinized TiO2 nanoparticles (Pt-TiO2). After 40 h of irradiation, systems containing Pt-RDM1, Pt-RDM2, and Pt-RDM3 exhibit turnover numbers (TONs) of 33600, 42800, and 70700, respectively. Ultrafast transient absorption spectroscopy reveals that energy transfer from the rhodamine (1)pi-pi*state to the singlet charge transfer ((CT)-C-1) state of the PtN2S2 chromophore occurs within 1 ps for all three dyads. Another fast charge transfer process from the rhodamine (1)pi-pi* state to a charge separated (CS) RDM(0.)-Pt(+.) state is also observed. Differences in the relative activity of systems using the RDM-PtN2S2 dyads for H-2 generation correlate well with the relative energies of the CS state and the (PtNS2)-S-2 (CT)-C-3 state used for H-2 production. These findings show how one can finely tune the excited state energy levels to direct excited state population to the photochemically productive states, and highlight the importance of judicious design of a photosensitizer dyad for light absorption and photoinduced electron transfer for the photogeneration of H-2 from aqueous protons.