Near-Infrared Luminescent PMMA-Supported Metallopolymers
Based on Zn–Nd Schiff-Base Complexes
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Abstract
On the
basis of self-assembly from the divinylphenyl-modified Salen-type
Schiff-base ligands <b>H</b><sub><b>2</b></sub><b>L</b><sup><b>1</b></sup> (<i>N</i>,<i>N</i>′-bis(5-(3′-vinylphenyl)-3-methoxy-salicylidene)ethylene-1,2-diamine)
or <b>H</b><sub><b>2</b></sub><b>L</b><sup><b>2</b></sup> (<i>N</i>,<i>N</i>′-bis(5-(3′-vinylphenyl)-3-methoxy-salicylidene)phenylene-1,2-diamine)
with Zn(OAc)<sub>2</sub>·2H<sub>2</sub>O and Ln(NO<sub>3</sub>)<sub>3</sub>·6H<sub>2</sub>O in the presence of pyridine (Py),
two series of heterobinuclear Zn–Ln complexes [Zn(L<sup><i>n</i></sup>)(Py)Ln(NO<sub>3</sub>)<sub>3</sub>] (<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><sup><b><i>n</i></b></sup><b>)(Py)Ln(NO</b><sub><b>3</b></sub><b>)</b><sub><b>3</b></sub><b>]</b> and Wolf Type
II Zn<sup>2+</sup>–Ln<sup>3+</sup>-containing metallopolymers <b>Poly(MMA-<i>co</i>-[Zn(L</b><sup><b><i>n</i></b></sup><b>)(Py)Ln(NO</b><sub><b>3</b></sub><b>)</b><sub><b>3</b></sub><b>])</b>, are obtained, respectively.
The result of their solid photophysical properties shows the strong and characteristic near-infrared
(NIR) luminescent Nd<sup>3+</sup>-centered emissions for both <b>PMMA/[Zn(L</b><sup><b><i>n</i></b></sup><b>)(Py)Nd(NO</b><sub><b>3</b></sub><b>)</b><sub><b>3</b></sub><b>]</b> and <b>Poly(MMA-<i>co</i>-[Zn(L</b><sup><b><i>n</i></b></sup><b>)(Py)Nd(NO</b><sub><b>3</b></sub><b>)</b><sub><b>3</b></sub><b>])</b>, where ethylene-linked hybrid materials endow relatively
higher intrinsic quantum yields due to the sensitization from both <sup>1</sup>LC and <sup>3</sup>LC of the chromorphore than those from
only <sup>1</sup>LC in phenylene-linked hybrid materials, and the
concentration self-quenching of Nd<sup>3+</sup>-based NIR luminescence
could be effectively prevented for the copolymerized hybrid materials
in comparison with the doped hybrid materials
