物理化学学报 >> 2014, Vol. 30 >> Issue (4): 745-752.doi: 10.3866/PKU.WHXB201402101

光化学和辐射化学 上一篇    下一篇

芳环上硝基取代基对苯甲酸功能化聚苯乙烯-Eu(Ⅲ)配合物光致发光性能的双重影响

许泽清, 高保娇, 侯晓东   

  1. 中北大学化学工程系, 太原030051
  • 收稿日期:2013-10-14 修回日期:2014-01-25 发布日期:2014-03-31
  • 通讯作者: 高保娇 E-mail:gaobaojiao@126.com
  • 基金资助:

    山西省自然科学基金(201002100843)资助项目

Twofold Influence of Nitro Substituent on Aromatic Ring for Photoluminescence Properties of Benzoic Acid-Functionalized Polystyrene and Eu(Ⅲ) Complexes

XU Ze-Qing, GAO Bao-Jiao, HOU Xiao-Dong   

  1. Department of Chemical Engineering, North University of China, Taiyuan 030051, P. R. China
  • Received:2013-10-14 Revised:2014-01-25 Published:2014-03-31
  • Contact: GAO Bao-Jiao E-mail:gaobaojiao@126.com
  • Supported by:

    The project was supported by the Natural Science Foundation of Shanxi Province, China (201002100843).

摘要:

将硝基苯甲酸配基(NBA)键合在聚苯乙烯侧链,制得了硝基苯甲酸功能化的聚苯乙烯(PS-NBA),在此基础上使大分子配体PS-NBA与Eu(Ⅲ)离子配位,制备了二元高分子-稀土配合物PS-(NBA)3-Eu(Ⅲ),也以邻菲罗啉(Phen)为小分子配体,制备了三元高分子-稀土配合物PS-(NBA)3-Eu(Ⅲ)-Phen1,重点研究了芳环上硝基取代基对高分子-稀土配合物光致发光性能的影响. 研究结果表明,芳环上的硝基取代基对以Eu(Ⅲ)为中心离子的苯甲酸功能化聚苯乙烯-稀土配合物的发光性能具有双重影响. 硝基取代基通过配基内的电荷转移(ILCT),耗损配基激发单线态的能量,有效降低苯甲酸配基的三线态能量,使配基NBA最低三线态能级与Eu(Ⅲ)离子共振能级之间的匹配程度显著增强,对Eu(Ⅲ)离子的荧光发射发生强敏化作用,使配合物PS-(NBA)3-Eu(Ⅲ)以及PS-(NBA)3-Eu(Ⅲ)-Phen1产生了高强度的荧光发射,显现出硝基取代基对配合物发光性能的正性影响. 另一方面,即使在稀溶液中,随着高分子-稀土配合物浓度从4.0×10-6 mol·L-1增大至4.0×10-4 mol·L-1,配合物的荧光发射也会逐渐变弱,这是由激发态的配合物向硝基发生荧光共振能量转移(FRET)的淬灭作用所导致的,表现出硝基取代基对配合物发光性能的负性影响.

关键词: 硝基取代基, 高分子-稀土配合物, 配基内电荷转移, 荧光共振能量转移, 双重影响

Abstract:

Nitrobenzoic acid (NBA) was bound to the side chains of polystyrene (PS) to give nitrobenzoic acidfunctionalized polystyrene (PS-NBA). By a coordination reaction of PS-NBA and a Eu3+ ion, a binary polymerrare earth complex PS-(NBA)3-Eu(Ⅲ) was prepared. Additionally, with phenanthroline (Phen) as a small molecular ligand, the ternary polymer-rare earth complex PS-(NBA)3-Eu(Ⅲ)-Phen1 was also prepared. In this work, the influence of the nitro-substituted aromatic ring on the photoluminescence properties of the polymerrare earth complexes of benzoic acid (BA)-functionalized polystyrene and a Eu3+ ion were studied. The experimental results show that the nitro-substituted benzene ring had a twofold influence on the photoluminescence properties of the polymer-rare earth complexes of the benzoic acid-functionalized polystyrene and the Eu(Ⅲ) ion. Upon an intraligand charge transfer (ILCT), the nitro substituent causes the excitation energy of the BA ligand to dissipate and causes the triplet state energy of the BA ligand to decrease. As a result, the match between the lowest triplet level of the NBA ligand and the resonance energy level of the Eu(Ⅲ) ion improved significantly. The NBA ligand strongly sensitized the florescence emission of the Eu(Ⅲ) ion leading to the PS-(NBA)3-Eu(Ⅲ) and PS-(NBA)3-Eu(Ⅲ)-Phen1 complexes producing strong florescence emission, which shows the positive effect of the nitro-substituted benzene ring on the luminescence properties of the complexes. However, even though the solution of the complex was dilute the florescence emissions of the complexes weakened with an increase in the concentration of the complexes from 4.0×10-4 to 4.0×10-6 mol·L-4. This was caused by fluorescence resonance energy transfer (FRET) in which the fluorescence resonance energy of the excited complex was transferred to the nitro group as an‘acceptor’species. This indicates a negative effect of the nitro substituent on the benzene ring on the luminescence properties of the complexes.

Key words: Nitro substituent, Polymer-rare earth complex, Intraligand charge transfer, Fluorescence resonance energy transfer, Twofold influence

MSC2000: 

  • O631