An Imidazole-Based Triangular Macrocycle for Visual Detection of Formaldehyde

Highly selective detection of formaldehyde utilizing supramolecules has promising applications in both environmental monitoring and biomonitoring areas. Herein we present a new class of imidazole-based, coordination-driven, self-assembled triangular macrocycles with specific recognition of formaldehyde. The visible fluorescence change to the naked eye from yellow to green-yellow occurs via an unusual reversible hydroxymethylation reaction of imidazole, whereas the corresponding imidazole ligands show no fluorescence change. This study provides a new method for efficient formaldehyde detection by utilizing imidazole-based coordination supramolecules

Near-Infrared Luminescent PMMA-Supported Metallopolymers Based on Zn–Nd Schiff-Base Complexes

On the basis of self-assembly from the divinylphenyl-modified Salen-type Schiff-base ligands <b>H</b>_<b>2</b><b>L</b>^<b>1</b> (<i>N</i>,<i>N</i>′-bis­(5-(3′-vinylphenyl)-3-methoxy-salicylidene)­ethylene-1,2-diamine) or <b>H</b>_<b>2</b><b>L</b>^<b>2</b> (<i>N</i>,<i>N</i>′-bis­(5-(3′-vinylphenyl)-3-methoxy-salicylidene)­phenylene-1,2-diamine) with Zn­(OAc)₂·2H₂O and Ln­(NO₃)₃·6H₂O in the presence of pyridine (Py), two series of heterobinuclear Zn–Ln complexes [Zn­(L^<i>n</i>)­(Py)­Ln­(NO₃)₃] (<i>n</i> = 1, Ln = La, <b>1</b>; Ln = Nd, <b>2</b>; or Ln = Gd, <b>3</b> and <i>n</i> = 2, Ln = La, <b>4</b>; Ln = Nd, <b>5</b>; or Ln = Gd, <b>6</b>) are obtained, respectively. Further, through the physical doping and the controlled copolymerization with methyl methacrylate (MMA), two kinds of PMMA-supported hybrid materials, doped <b>PMMA/[Zn­(L</b>^{<b><i>n</i></b>}<b>)­(Py)­Ln­(NO</b>_<b>3</b><b>)</b>_<b>3</b><b>]</b> and Wolf Type II Zn²⁺–Ln³⁺-containing metallopolymers <b>Poly­(MMA-<i>co</i>-[Zn­(L</b>^{<b><i>n</i></b>}<b>)­(Py)­Ln­(NO</b>_<b>3</b><b>)</b>_<b>3</b><b>])</b>, are obtained, respectively. The result of their solid photophysical properties shows the strong and characteristic near-infrared (NIR) luminescent Nd³⁺-centered emissions for both <b>PMMA/[Zn­(L</b>^{<b><i>n</i></b>}<b>)­(Py)­Nd­(NO</b>_<b>3</b><b>)</b>_<b>3</b><b>]</b> and <b>Poly­(MMA-<i>co</i>-[Zn­(L</b>^{<b><i>n</i></b>}<b>)­(Py)­Nd­(NO</b>_<b>3</b><b>)</b>_<b>3</b><b>])</b>, where ethylene-linked hybrid materials endow relatively higher intrinsic quantum yields due to the sensitization from both ¹LC and ³LC of the chromorphore than those from only ¹LC in phenylene-linked hybrid materials, and the concentration self-quenching of Nd³⁺-based NIR luminescence could be effectively prevented for the copolymerized hybrid materials in comparison with the doped hybrid materials