Interaction of Lanthanide β-Diketonate Complexes with Polyvinylpyrrolidone: Proton-Controlled Switching of Tb3+ Luminescence
Interaction of Lanthanide β-Diketonate Complexes with Polyvinylpyrrolidone: Proton-Controlled Switching of Tb3+ Luminescence
复制标题
DOI：
10.1021/jp408328h
复制
发表时间：
2014-01-09
影响因子：
3.3
通讯作者：
Buczko, K.
中科院分区：
文献类型：
--
作者：
Karbowiak, M.;Cichos, J.;Buczko, K.
本文用荧光光谱法系统地研究了稀土β-二酮配合物与聚乙烯吡咯烷酮（PVP）的相互作用。在无H+存在下，PVP几乎完全猝灭了铽与六氟乙酰丙酮（hfa）配合物的荧光，而在H+存在下，荧光增强了30倍以上。相反，H+离子增加铽与乙酰丙酮配体的配合物的猝灭效率。与氟化和非氟化的β-二酮的配合物的显着不同的行为占的相互作用机制，其中氢键的重要作用被指示。该机理包括配体O-C-CH 2-C-O基团上的负电荷与PVP吡咯烷酮基团N原子上的正电荷之间的离子偶极库仑相互作用，以及配体C-O基团与PVP之间直接或通过溶剂分子形成的氢键相互作用。另外的稳定作用，显着影响与PVP的配体的结合强度，由末端（CF 3或CH 3）取代基形成的氢键，与PVP的C-O基团的配体的结果。重要的是，铽与六氟甲磺酸配体的配合物在PVP溶液中的发光的猝灭和增强是一个可逆的过程。这使得人们能够获得由H+离子外部触发的发射开关ON系统，这可以在基于分子的器件的开发中找到可能的应用。
In the present study the interaction of lanthanide beta-diketonate complexes with polyvinylpyrrolidone (PVP) has been systematically investigated using fluorescence spectroscopy. The emission of terbium complexes with hexafluoroacety-lacetone (hfa) ligands is almost completely quenched by PVP in the absence of H+ ions, while it is enhanced by more than 30 times in the presence of H+ ions. Conversely, the H+ ions increase the quenching efficiency of terbium complex with acetylacetone ligands. The strikingly different behavior of complexes with fluorinated and nonfluorinated beta-diketonates is accounted for by the interaction mechanism, in which the important role of hydrogen bonds is indicated. The proposed mechanism includes ion-dipol Coulombic interactions between negative charge localized on ligands O-C-CH2-C-O group and positive charge induced in N atom of PVP pyrrolidone group, as well as interactions through hydrogen bonds formed between ligand C-O groups and PVP, occurring directly or through solvent molecules. Additional stabilizing effect, significantly influencing the binding strength of ligands with PVP, results from hydrogen bonds formed by terminal (CF3 or CH3) substituents, of ligands with C-O group of PVP. Importantly, the quenching and enhancement of luminescence of terbium complexes with hfa ligands in PVP solution is a reversible process. This enables one to obtain the emission switch-OFF ON system triggered externally by H+ ions, which can find possible application in the development of molecule-based devices.