Singlet and Triplet Energy Transfers in Tetra-(meso-truxene)zinc(II)- and Tetra-(meso-tritruxene)zinc(II) Porphyrin and Porphyrin-Free Base Dendrimers
摘要:
The synthesis, optical properties, and energy transfer features of four dendrimers composed of meso-tetrasubstituted zinc(II) porphyrin (ZnP) or a free base (P) central core, where the substituents are four truxene (Tru) or four tritruxene dendrons (TriTru), TruP, TriTruP, TruZnP, and TriTruZnP, are reported. Selective excitation of the truxene donors results in a photoinduced singlet energy transfer from the truxenes to the porphyrin acceptor. The rates for singlet energy transfer (k(ET)), evaluated from the change in the fluorescence lifetime of the donors (Tru and TriTru) in the presence and absence of the acceptor (P or ZnP) for TruP, TruZnP, TriTruP, and TriTruZnP, are 5.9, 1.2, 0.87, and 0.74 (ns)(-1) at 298 K and 2.6, 2.6, 2.7, and 1.2 (ns)(-1) at 77 K, respectively. A slow triplet-triplet energy transfer from tnixene to porphyrin cores in glassy 2MeTHF at 77 K is also reported with rates of 1.3 x 10(3) and 0.10 X 10(2) s(-1) for TruZnP and TriTruZnP, respectively. Tithe Dexter mechanism for the triplet energy transfers is considered, these slow rates are easily explained by a poor orbital overlap between the truxene and porphyrin pi systems. The fluorescence quantum yields (Phi(F)) are 0.20 and 0.16 for TruP and TriTruP and 0.08 and 0.10 for TruZnP and TriTruZnP, respectively at 298 K At 298 K, a phosphorescence from TruZnP at 795 nm was also observed and is associated with the ZnP chromophore.
茚并[2,1- c ]芴的烷基化骨架被认为是茚并[1,2- b ]芴的位置异构体,它通过Pd催化的Suzuki有机光耦合反应,构建了几种共轭的低聚物和聚合物。发光二极管。单晶分析表明,茚满[2,1- c ]芴的结构由于分子拥挤区域中的紧密H --- H接触而扭曲。P1-P3在常见的有机溶剂中显示出良好的溶解性,并且易于形成膜。与线性正烷基取代的低聚(茚并[1,2- b ]芴)和聚(茚并[1,2- b ]芴)(2,8-PIFs),稀溶液中扭曲的n-烷基取代的低聚(茚并[2,1- c ]芴)和聚(茚并[2,1- c ]芴)(P1)的吸收和发射特征与共轭长度,并且由于主链扭曲而明显蓝移。在稀释溶液和薄膜中,所有聚合物均发出强烈的蓝色荧光,其半峰宽(半峰宽)(约50 nm)非常窄。制作了具有ITO / PEDOT:PSS / PVK / polymers / Ba / Al构型的电致发光(EL)器件,以实现蓝色EL发射,在10