Irreversible Solvatochromic Zn-Nanopaper Based on Zn(II) Terpyridine Assembly and Oxidized Nanofibrillated Cellulose

Abstract

A new irreversible solvatochromic Zn-nanopaper has been produced through the coordination-driven assembly of Zn­(II)-terpyridine complex (Zn-tpy) on the surface of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibril (tCNF). The Zn-tpy as a photoactive center exhibits a changed emission color from greenish-blue to yellow after coordination with the carboxylate anion on the surface of tCNF. Theoretic calculations support that the longer wavelength emission is the result of a metal–ligand charge transfer. When exposed to solvents and then dried, the coordination bond between the Zn-tpy and tCNF experienced a dynamic, reversible process, where the lowest-energy excited state emitted by the Zn-tpy was “inverted”, which is a typical phenomenon of irreversible solvatochromism. The shifts of the emission colors of the Zn-nanopaper appeared result from its exposure to specific solvents and occurred in a matter of minutes. After solvent exposure, it was found that the emission colors of the nanopaper are not recovered to its original state. The different emissive Zn-nanopapers are easily prepared by post-processing using a solvatochromic process. This highly transparent Zn-nanopaper with post-processable emission offers unprecedented potential applications in the areas of memory devices, fluorescent switches, and organic light-emitting diodes (OLEDs).

Transparent and Hazy EuxTb1–x-Nanopaper with Color-Tuning, Photo-Switching, and White Light-Emitting Properties for Anti-counterfeiting and Light-Softened WLEDs

“…Absorption peaks at 1583 and 2343 cm –1 were observed, corresponding to tCNF carboxyl (CO) unsaturated groups and O–H tensile vibrations, respectively. Compared with tCNF (nanopaper, 1602 cm –1 ), the peak was 19 cm –1 blue-shifted at 1583 cm –1 , which might be attributed to the coordination of carboxyl and lanthanide (Ln, including Gd, Eu, and Tb) ions . Furthermore, because of the stretching vibrations of the N–H group and the group from the deprotonated H 3 imdc ligand, the spectra of Ln-nanopaper and Ln-MOFs showed characteristic signal peaks at 3120 and 1240 cm –1 , respectively (Figure S3).…”

“…Compared with tCNF (nanopaper, 1602 cm −1 ), the peak was 19 cm −1 blueshifted at 1583 cm −1 , which might be attributed to the coordination of carboxyl and lanthanide (Ln, including Gd, Eu, and Tb) ions. 22 Furthermore, because of the stretching vibrations of the N−H group and the group from the deprotonated H 3 imdc ligand, the spectra of Ln-nanopaper and Ln-MOFs showed characteristic signal peaks at 3120 and 1240 cm −1 , respectively (Figure S3). The elemental compositions of Eu 0.5 Tb 0.5 -MOFs and Eu 0.5 Tb 0.5 -nanopapers were detected by X-ray photoelectron spectroscopy (XPS).…”

Highly Stable Polyoxovanadate-Based Zn–MOF with Dual Active Sites as a Solvent-free Catalyst for C–C Bond Formation

“…As depicted in Figure S3, the peaks with binding energies of 517.15 and 1021.42 eV in XPS of the V-Zn-MOF are consistent with the value of V(V) 2p 3/2 and Zn(II) 2p 3/2 , respectively. 34,35 Meanwhile, the TGA experiment is performed on the V-Zn-MOF under N 2 atmosphere, and the results show that the V-Zn-MOF remains stable up to 370 °C (Figure S4). In addition, the stability of the V-Zn-MOF is further tested by immersing it in various solvents, including boiling THF, acetone, hexane, EtOH, ACN, H 2 O, and 100 °C DMF, for 24 h; the PXRD patterns and FTIR spectra of the experimental V-Zn-MOF are matched well with that of the freshly prepared sample (Figure 2).…”

Design and Synthesis of Fluorescent Nanocelluloses for Sensing and Bioimaging Applications

“…TEMPO oxidation can selectively oxidize the primary hydroxyl group at the C6 site to a carboxyl group, increasing the negative charge and thus improving NC hydrophilicity. Studies have used carboxylated NC fibers as a matrix for preparing flexible fluorescent films after coordination with transition‐metal complexes . The Malaprade reaction can oxidize two secondary hydroxyl groups to aldehyde groups.…”