Nanoscale Ln(III)-Carboxylate Coordination Polymers (Ln = Gd, Eu, Yb): Temperature-Controlled Guest Encapsulation and Light Harvesting

Abstract

We report the self-assembly of stable nanoscale coordination polymers (NCPs), which exhibit temperature-controlled guest encapsulation and release, as well as an efficient light-harvesting property. NCPs are obtained by coordination-directed organization of pi-conjugated dicarboxylate (L1) and lanthanide metal ions Gd(III), Eu(III), and Yb(III) in a DMF system. Guest molecules trans-4-styryl-1-methylpyridiniumiodide (D1) and methylene blue (D2) can be encapsulated into NCPs, and the loading amounts can be controlled by changing reaction temperatures. Small angle X-ray diffraction (SAXRD) results reveal that the self-assembled discus-like NCPs exhibit long-range ordered structures, which remain unchanged after guest encapsulations. Experimental results reveal that the negatively charged local environment around the metal connector is the driving force for the encapsulation of cationic guests. The D1 molecules encapsulated in NCPs at 140 degrees C can be released gradually at room temperature in DMF. Guest-loaded NCPs exhibit efficient light harvesting with energy transfer from the framework to the guest D1 molecule, which is studied by photoluminescence and fluorescence lifetime decays. This coordination-directed encapsulation approach is general and should be extended to the fabrication of a wide range of multifunctional nanomaterials.

Multi-scale crystal engineering of metal organic frameworks

“…In the synthesis of [Gd-L1] n nanodiscs (L1 = π-conjugated dicarboxylate ligand), DMF proved to be a good stabilizer for monodisperse CP particles, whereas DMSO solvent leads to aggregation of these particles [99]. Additionally, the morphology switching from nanowires to nanorods have been observed for [Pr(1,3,5-BTC)(H 2 O) 6 ] n architectures when ethanol was used as a solvent instead of an ethanol/water mixture [100].…”

Rare earth based nanostructured materials: synthesis, functionalization, properties and bioimaging and biosensing applications

“…In the case of MOFs, the fluorophores can be part of the MOF structure, as it is the case of benzodinitrile-based MOF [229], or can be introduced as a guest, as in carboxylate-based Ln MOF loaded with trans-4-styryl-1-methylpyridiniumiodide and methylene blue [230].…”

Synthesis of Cu<SUP>II</SUP>-Nanocrystal Coordination Polymer by Microemulsion Method. Straightforward Experiment of Nanomaterial Synthesis for Science High School Students

“…For instance, macroscopic solid CPs mostly show limited solutionbased behavior [5], but decreasing their size down to the nanoscale can afford novel properties which are different from the bulk crystal, such as colloidal dispersibility [6]. The versatile nanoscale properties of NCPs can expand the utility of the macroscale CPs above and beyond structural investigations in terms of crystal engineering, which have formed the bulk of the work in the general research area.…”