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Anthryl-Appended Platinum(II) Schiff Base Complexes: Exceptionally Small Stokes Shift, Triplet Excited States Equilibrium, and Application in Triplet-Triplet-Annihilation Upconversion.
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2020-08-31 , DOI: 10.1021/acs.inorgchem.0c01932
Kepeng Chen 1 , Mushraf Hussain 1 , Syed S Razi 1, 2 , Yuqi Hou 1 , Elif Akhuseyin Yildiz 3 , Jianzhang Zhao 1 , Halime Gul Yaglioglu 3 , Mariangela Di Donato 4, 5
Affiliation  

Two anthryl platinum(II) N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-benzenediamine Schiff base complexes were synthesized, with the anthryl attached via its 9 position (Pt-9An) or 2 position (Pt-2An) to the platinum (Pt) Schiff base backbone. The complexes show unusually small Stokes shifts (0.23 eV), representing a very small energy loss for the photoexcitation/intersystem crossing process, which is beneficial for applications as triplet photosensitizers. Phosphorescence of the Pt(II) coordination framework (ΦP = 11.0%) is quenched in the anthryl-containing complexes (ΦP = 4.0%) and shows a biexponential decay (τP = 3.4 μs/87% and 18.2 μs/13%) compared to the single-exponential decay of the native Pt(II) Schiff base complex (τP = 3.7 μs). Femtosecond/nanosecond transient absorption spectroscopy suggests an equilibrium between triplet anthracene (3An) and triplet metal-to-ligand charge-transfer (3MLCT) states, with the dark 3An state slightly lower in energy (1.96 eV for Pt-9An and 1.90 eV for Pt-2An) than the emissive 3MLCT state (1.97 eV for Pt-9An and 1.91 eV for Pt-2An). Intramolecular triplet–triplet energy transfer (TTET) and reverse TTET take 4.8 ps/444 ps for Pt-9An and 55 ps/1.7 ns for Pt-2An, respectively. The triplet-state equilibrium extends the triplet-state lifetime of the complexes to 103 μs (Pt-2An) or 163 μs (Pt-9An), in comparison to the native Pt(II) complex, which shows a lifetime of 4.0 μs. The complexes were used for triplet–triplet-annihilation upconversion with perylene as the triplet acceptor. The upconversion quantum yield is up to 15%, and a large anti-Stokes shift (0.75 eV) is achieved by excitation into the singlet metal-to-ligand charge-transfer absorption band (589 nm) of the complexes (anti-Stokes shift is 0.92 eV with 9,10-diphenylanthracene as the acceptor).

中文翻译:

蒽基附加的Schiff碱铂(II)配合物:异常小的斯托克斯位移,三重态激发态平衡,以及在三重态-三重态Ann灭上转换中的应用。

合成了两个蒽铂(II)NN'-双(3,5-二叔丁基水杨基)-1,2-苯二胺席夫碱配合物,其中蒽基通过其9位(Pt-9An)或2连接铂(Pt)Schiff基础骨架的位置(Pt-2An)。配合物显示出异常小的斯托克斯位移(0.23 eV),代表光激发/系统间交叉过程的能量损失非常,这对于三重态光敏剂的应用是有益的。铂(II)协调框架磷光(Φ P = 11.0%)在含有蒽基的络合物(Φ猝灭P = 4.0%)和示出了双指数衰减(τ P=相比于天然的Pt的单指数衰减(3.4微秒/ 87%和18.2μS/ 13%)II)席夫碱络合物(τ P = 3.7微秒)。飞秒/纳秒瞬态吸收光谱表明,三重态蒽(3 An)和三重态金属到配体的电荷转移(3 MLCT)状态之间达到平衡,而暗3 An态的能量略低(Pt-9AnPt-9An为1.96 eV)。对于Pt-2An而言为1.90 eV,而不是发射3 MLCT状态(对于Pt-9An为1.97 eV,对于Pt-2An为1.91 eV )。Pt-9An分子内三重态-三重态能量转移(TTET)和反向TTET耗时4.8 ps / 444 psPt-2An分别为55 ps / 1.7 ns 。与天然Pt(II)络合物的寿命为4.0μs相比,三重态平衡使络合物的三重态寿命延长至103μsPt-2An)163μsPt-9An)。配合物用于per的三重态-三重态-灭上转换,per为三重态受体。上转换量子产率高达15%,并且通过激发进入配合物的单重态金属到配体的电荷转移吸收带(589 nm)中实现了大的反斯托克斯位移(0.75 eV)为0.92 eV,9,10-二苯基蒽为受体)。
更新日期:2020-10-21
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