A Biphenol-Based Chemosensor for Zn^II and Cd^II Metal Ions: Synthesis, Potentiometric Studies, and Crystal Structures

Abstract

We synthesized and characterized the ligand N,N'-bis[(2,2'-dihydroxybiphen-3-yl)methyl]-N,N'-dimethylethylenediamine (L), which contains two biphenol moieties linked as side arms to an N,N'-dimethylethylenediamine scaffold. The ligand is highly soluble in a 50/50 (v/v) water/ethanol mixture and, in its deprotonated form H-2L(2-), is able to coordinate transition-metal ions such as Ni(II), Zn(II), Cu(II), Cd(II), and Pd(II). The crystal structures of [Ni(H-2L)·2n-BuOH], [Ni(H-2L)·2MeOH], [Cd(H-2L)·2DMF], [Cu(H-2L)(DMF)], and [Pd(H-2L)(DMF)] were also determined and described. Potentiometric titrations were carried out in a mixed solvent with Zn(II), Cu(II), and Ni(II) metal ions to determine the acid-base and stability constants. L was highly fluorescent in the visible range (400 nm). Moreover, its emission intensity increased upon the addition of Zn(II) or Cd(II) ions in an ethanol/water solution and behaved as a chemosensor for the presence of these ions in the solution.

A New Family of Macrocyclic Polyamino Biphenolic Ligands: Acid-Base Study, Zn(II) Coordination and Glyphosate/AMPA Binding

“…Of particular interest is the coupling of polyamine-based receptor units with phenolic groups as signaling moieties [37,43,44], in the realization of versatile and effective polyamino-phenolic receptors for anionic targets. Indeed, the phenolic functions confer to these systems peculiar photochemical behaviors, making it possible to detect a selected substrate via an optical response, namely by fluorescence signaling [44,45], but they can be also involved, as phenolates, in metal-coordination, affording efficient metallo-receptors for anionic guests [38,46,47].…”

Improved Access to 1,8-Diformyl-carbazoles Leads to Metal-Free Carbazole-Based [2 + 2] Schiff Base Macrocycles with Strong Turn-On Fluorescence Sensing of Zinc(II) Ions

“…Zinc ions are essential to life and play a wide range of roles throughout biology, so the development of chemosensors capable of visualizing them by, preferably “turn-on”, fluorescence has been the subject of considerable activity. − Recent work into sensing zinc ions by chelation enhancement of fluorescence has utilized both acyclic − and macrocyclic − ligands as probes. Macrocyclic probes, such as well-known Robson and corrole macrocycles, are favored due to stabilization of the resulting complex by the macrocyclic effect.…”

Tetranuclear and 1D Polymeric Cd(II) Complexes with a Tetrapyridyl Imidazolidine Ligand: Synthesis, Structure, and Fluorescence Sensing Activity

“…34−40 Among a number of polynuclear compounds containing organic ligands showing selective fluorescence sensing for aromatic organic compounds, 41−44 a Cd(II) compound inserted in a rigid matrix also showed luminescence behavior. 45,46 Nitroaromatic compounds such as 2,4,6trinitrophenol (TNP), 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), etc. are widely used as components of industrial explosives.…”

“…Detection of ultratrace analytes is an important area of research, and fluorescence quenching based detection of analytes is widely used, as it is a method of high sensitivity, easy visualization, and real-time monitoring with a fast response time. − Among a number of polynuclear compounds containing organic ligands showing selective fluorescence sensing for aromatic organic compounds, − a Cd­(II) compound inserted in a rigid matrix also showed luminescence behavior. , Nitroaromatic compounds such as 2,4,6-trinitrophenol (TNP), 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), etc. are widely used as components of industrial explosives.…”