Synthesis and spectroscopic properties of axial phenoxide and para amino phenoxide incorporated indium (III) porphyrins
Synthesis and spectroscopic properties of axial phenoxide and para amino phenoxide incorporated indium (III) porphyrins
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DOI：
10.1016/j.molstruc.2019.05.120
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发表时间：
2019-11-05
影响因子：
3.8
通讯作者：
Bajju, Gauri Devi
中科院分区：
文献类型：
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作者：
Dechan, Padma;Bajju, Gauri Devi
我们成功地合成了四-4-甲氧基苯基铟(III)卟啉，并对其进行了光谱表征。用粉末X-射线衍射仪分析了所制备的卟啉的物相和结构变化。酚类基团的轴向配位导致大环铟卟啉的核磁共振氢谱信号略有移动。对卟啉在CH2Cl2和CH3COOC2H5中的紫外-可见吸收光谱的测量表明，在中性pH条件下，轴向配位的金属络合物的吸收带比未配位的金属卟啉表现出更高的色度。最显著的特点是在碱性介质(pH=10)和酸性介质(pH=4)下的结构稳定性。另一方面，无金属配体5，10，15，20-四(4-甲氧基苯基)卟啉，H_2TMP(I)在酸性介质(pH=4)中发生J型聚集。铟的稳定性，特别是在酸性介质中，与其他表面(SAT)或平面外(OOP)的络合物相反，它们通常在酸性条件下发生脱金属化。所有制备的大环在CH3COOC2H5(强极性)中的吸收带蓝移比在CH2Cl2(弱极性)中的吸收带蓝移反映出负的溶致变色。由于In(III)的内部重原子效应和配位面的扭曲，In(III)的光致发光相对于无金属配体(I)有显著的猝灭作用。在轴向连接的金属卟啉中，荧光带的猝灭更为明显。铟(III)卟啉的激发态寿命比自由碱类似物(I)的激发态寿命短，这可能归因于铟(III)离子在相应的金属络合物中引起的自旋轨道耦合。(C)2019爱思唯尔B.V.保留所有权利。
Tetrakis-4-methoxyphenyl indium(III) porphyrins containing phenolic and para amino phenolic moieties in the apical sites have been successfully prepared and characterized spectroscopically. The phases and structure evolutions of prepared porphyrins were deduced from powder X-ray diffraction (PXRD). The axial coordination of phenolic moieties induces slight shift of the H-1 NMR signals of indium porphyrin macrocycles. The measurements of UV-Visible absorptions of porphyrins in CH2Cl2 and CH3COOC2H5 reflects that axially ligated metal chelates at neutral pH display hyperchromicity of absorption bands compared to unligated metal porphyrin. The most striking feature was the structural stability of indium porphyrins under basic (pH = 10) as well as acidic media (pH = 4). On the other hand, the metal free ligand 5, 10, 15, 20-Tetrakis-(4-methoxyphenyl) porphyrin, H2TMP (I) undergoes J type aggregation in acidic media (pH = 4). The robustness of indium porphyrins especially in acidic media are in strong contrary to other sitting atop (SAT) or out of plane (OOP) complexes which are usually demetallized under acidic pH. All the prepared macro rings exhibit negative solvatochromism reflected by the blue shift of absorption bands in CH3COOC2H5 (more polar) than in CH2Cl2 (less polar). The photo-luminescence emissions in indium(III) species are significantly quenched relative to metal free ligand (I) due to internal heavy atom effect and distortion of ligand plane. The quenching of fluorescence bands are more pronounced in axially ligated metal porphyrins. The lesser excited state lifetimes of indium(III) porphyrins relative to free base analog (I) may be ascribed to spin orbit coupling induced by indium(III) ion in the respective metal chelates. (C) 2019 Elsevier B.V. All rights reserved.