From Two-Dimensional Metal—Organic Coordination Networks to Near-Infrared Luminescent PbS Nanoparticle/Layered Polymer Composite Materials

Two-dimensional (2-D) layered metal-organic coordination (lead methacrylate (LDMA)) networks have been prepared in aqueous solution under mild conditions and their structure determined by single crystal diffraction. As the ligand used in our experiments is easily polymerized, these metal-organic coordination layers are therefore employed as precursors to fabricate cross-linked polymer layered materials through γ-irradiated polymerization. The stabilities of the samples are significantly improved after γ-irradiation. To our knowledge, this is the first time that covalent bonded polymer layered structures have been fabricated without the assistance of added surfactant or template. Such layered polymer materials cannot only act as alternatives to layered inorganic materials in some caustic environments, but also allow the generation of PbS nanoparticles (NPs) without aggregation in the polymer matrix. By exposing the polymer layer to H₂S gas at room temperature, uniform PbS nanoparticles with an average size of about 6 nm are generated in situ. In addition, the resulting PbS NPs exhibit near-infrared (NIR) luminescent properties, which suggests the composite materials may be useful as active optical elements at communication wavelengths from 1300 to 1550 nm.