Sendh Jagajiban, Baruah Jubaraj B
Department of Chemistry, Indian Institute of Technology Guwahati Guwahati-781 039 Assam India
RSC Adv. 2024 Oct 7;14(43):31598-31606. doi: 10.1039/d4ra06309k. eCollection 2024 Oct 1.
Distinct changes in the fluorescence emissions of free ligand 5-(1,3-dioxo-1-benzo[de]isoquinolin-2(3)-yl)isophthalic acid (HNAPHISO) than a 2D-zinc-coordination polymer of it, caused by sequential interactions with different sets of binary cations were observed. The coordination polymer having unsymmetrical ZnO core of tetranuclear zinc-node could be dispersed in dimethylformamide without its degradation. The coordination polymer had an emission peak at 435 nm (quantum yield = 0.082) which was selectively quenched by adding Fe ions. Based on this quenching, the Fe ions in aqueous solution could be detected with a detection limit 42.57 nM. The metal ions such as Li, Na, Cd, Hg, Al did not interfere in the detection; but each of these ions together with Fe ions showed characteristic shift of the emission spectra. The HNAPHISO in dimethyl formamide was non-fluorescent, but showed emission at 452 nm upon addition of Cd or Zn ions. This new emission of HNAPHISO caused by zinc or cadmium ions was not quenched by Fe ions. Various cations had affected the emission of the HNAPHISO with Zn which was much different from the corresponding changes caused by the same ion on the emission of the coordination polymer. For example, the Mn and Zn ions together in a solution of the ligand showed a broad emission spectrum spreading over 380-450 nm, but ions Sn and Zn together had showed emission at a shorter wavelength (380 nm). These allowed to modulate the emission of the ligand by binary combination of metal ions.
观察到，与游离配体5-(1,3-二氧代-1-苯并[de]异喹啉-2(3)-基)间苯二甲酸(HNAPHISO)相比，其二维锌配位聚合物的荧光发射因与不同二元阳离子组的顺序相互作用而发生明显变化。具有四核锌节点不对称ZnO核心的配位聚合物可分散在二甲基甲酰胺中而不降解。该配位聚合物在435 nm处有一个发射峰(量子产率=0.082)，加入铁离子后该发射峰被选择性猝灭。基于这种猝灭作用，可检测水溶液中的铁离子，检测限为42.57 nM。锂、钠、镉、汞、铝等金属离子不干扰检测；但这些离子中的每一种与铁离子一起时，发射光谱都有特征性位移。二甲基甲酰胺中的HNAPHISO无荧光，但加入镉或锌离子后在452 nm处发射荧光。锌或镉离子引起的HNAPHISO这种新发射不受铁离子猝灭。各种阳离子对含锌HNAPHISO的发射有影响，这与相同离子对配位聚合物发射的相应变化有很大不同。例如，配体溶液中的锰离子和锌离子一起显示出覆盖380 - 450 nm的宽发射光谱，但锡离子和锌离子一起时在较短波长(380 nm)处发射。这些使得通过金属离子的二元组合来调节配体的发射。
