Electrogenerated Chemiluminescence from Heteroleptic Iridium(III) Complexes with Multicolor Emission
Electrogenerated Chemiluminescence from Heteroleptic Iridium(III) Complexes with Multicolor Emission
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具有多色发射的杂配铱 (III) 配合物的电致化学发光
DOI：
10.1021/ic502444k
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发表时间：
2015
影响因子：
4.6
通讯作者：
Qi Honglan
中科院分区：
文献类型：
--
作者：
Zhou Yuyang;Gao Hongfang;Wang Xiaomei;Qi Honglan
不同发射颜色的电致化学发光（ECL）在多通道分析技术的发展中具有重要意义。本文合成了5种新的杂电性铱配合物，并对其光物理、电化学和ECL性能进行了研究。本文以2-（2,4-二氟苯基）吡啶（dppy，络合物1）、2-苯基苯并[d]噻唑（bt，络合物2）和2-苯基吡啶（ppy，络合物3）为主要配体调节其发光颜色，以阿伏苯宗（avo）为辅助配体。为了比较，还分别合成了以2-苯基吡啶和2-苯基苯并[d]噻唑为主配体，乙酰丙酮（acac）为辅助配体的配合物4和5。这5种铱（III）配合物在350 nm以下的紫外区具有较强的配体内吸收带（π -π *），在400-500 nm范围内具有无特征的MLCT （d−π*）跃迁。这五种铱（III）配合物的发射光谱呈现出多种颜色，其中配合物4,5,2,1,3的发射光谱分别为绿色、橙色和红色。密度泛函理论计算表明，最高已占据分子轨道的电子密度完全位于C^N配体和铱原子上，而最低未占据分子轨道（LUMO）的形成较为复杂。对于络合物1和3，LUMO主要分配给辅助配体，而对于络合物2、4和5，LUMO主要分配给C^N配体。循环伏安法研究表明，这些配合物均存在可逆氧化波，但在CH2Cl2的电化学窗口内未发现还原波。络合物3、4、2、5、1的e1 /2o值依次为0.642 ~ 0.978 V，均低于Ru(bpy)32+的e1 /2o值。最重要的是，当使用三丙胺作为共反应物时，配合物1 - 5表现出强烈的ECL信号，发射波长分别为616、580、663、536和569 nm。此外，在相同条件下，配合物1、2和5的ECL效率分别是Ru(bpy)32+的2倍、11倍和214倍。
Electrogenerated chemiluminescence (ECL) with different emission colors is important in the development of multichannel analytical techniques. In this report, five new heteroleptic iridium(III) complexes were synthesized, and their photophysical, electrochemical, and ECL properties were studied. Here, 2-(2,4-difluorophenyl)pyridine (dfppy, complex1), 2-phenylbenzo[d]thiazole (bt, complex2), and 2-phenylpyridine (ppy, complex3) were used as the main ligands to tune the emission color, while avobenzone (avo) was used as the ancillary ligand. For comparison, complexes4and5with 2-phenylpyridine and 2-phenylbenzo[d]thiazole as the main ligand, respectively, and acetyl acetone (acac) as the ancillary ligand were also synthesized. All five iridium(III) complexes had strong intraligand absorption bands (π–π*) in the UV region (below 350 nm) and a featureless MLCT (d−π*) transition in the visible 400–500 nm range. Multicolored emissions were observed for these five iridium(III) complexes, including green, orange, and red for complexes4,5,2,1,3, respectively. Density functional theory calculations indicate that the electronic density of the highest occupied molecular orbital is entirely located on the C^N ligands and the iridium atom, while the formation of the lowest unoccupied molecular orbital (LUMO) is complicated. The LUMO is mainly assigned to the ancillary ligand for complexes1and3but to the C^N ligand for complexes2,4, and5. Cyclic voltammetry studies showed that all these complexes have a reversible oxidation wave, but no reduction waves were found in the electrochemical windows of CH2Cl2. TheE1/2oxvalues of these complexes ranged from 0.642 to 0.978 V for complexes3,4,2,5,1, (in increasing order) and are all lower than that of Ru(bpy)32+. Most importantly, when using tripropylamine as a coreactant, complexes1–5exhibited intense ECL signals with an emission wavelength centered at 616, 580, 663, 536, and 569 nm, respectively. In addition, complexes1,2, and5displayed approximately 2, 11, and 214 times higher ECL efficiencies than Ru(bpy)32+under identical conditions.