Dehydration-Triggered Afterglow Transition in a Mellitate-Based Coordination Polymer

Abstract

Stimulus-responsive long persistent luminescence (LPL) materials have attracted wide attention due to their potential applications in information storage, anti-counterfeiting, optoelectronic devices, etc. However, LPL coordination polymers with room temperature afterglow transition characteristics have not been explored. Herein, mellitic acid and zinc ions were utilized to synthesize an acid–base stable coordination polymer (1) by an organic solvent-free hydrothermal method. 1 possesses a tightly stacked structure and exhibits dual-emission peaks with blue luminescence and blue-green afterglow. Upon exposure to heating, DMSO immersion, or vacuum, 1h, 1s, and 1v were obtained. The original blue luminescence changes to blue-green, while the afterglow turns yellow-green due to the loss of water molecules from the inner cavity. This is the first example of an LPL coordination polymer that can realize room temperature afterglow transition by dehydration operation. Moreover, the emission spectra of 1 can be recovered by exposing 1h, 1s, or 1v to water vapor, suggesting a reversible dehydration/hydration process. Experimental and density functional theory (DFT) results suggest that the fluorescence of 1 originates from the mixing of intra-ligand and ligand-to-metal charge transfer excited states. The triplet state from intersystem crossing is responsible for the long persistent luminescence of phosphorescence emission. The rational structural design along with the conceptual model of anti-counterfeiting and information encryption based on afterglow transition display the unique advantages of the LPL coordination polymer in realizing convenient multiple stimuli-responsive devices.

A flexible ligand and halogen engineering enable one phosphor-based full-color persistent luminescence in hybrid perovskitoids

“…This suggests that the luminescence of CdX-apim1 is generated from the imidazole parts because the emission of the aminopropyl group can be basically ignored in solution. [29][30][31][32][33][34][35][36] Aer removing the 365 and 395 nm UV lamp, CdCl-apim1 shows cyan and yellow emission, respectively, exhibiting excitation wavelength-dependent aerglow properties. As shown in Fig.…”

“…31 Crystalline metal-organic hybrids (MOHs), as an important branch of molecular RTP materials, have many unique advantages to obtain recognizable persistent luminescence. 18,[32][33][34][35][36][37][38] By providing a rigid environment and promoting heavy atom effects (HAE), MOHs could achieve long-lived RTP and highefficiency aerglow simultaneously. The color-tunable persistent luminescence can also be realized by manipulating the coordination mode and molecular conguration.…”

Encapsulation engineering of porous crystalline frameworks for delayed luminescence and circularly polarized luminescence

“…In this case, MOFs feature intrinsic advantages as containers to construct host–guest systems for the generation, enhancement and regulation of phosphorescence. 270–273 On the one hand, MOFs can boost the rigidification of phosphorescence ligands and minimize the nonradiative transition of triplet excitons. 274–276 On the other hand, the phosphorescence emitters as guests encapsulated in MOFs can efficiently reduce the aggregation-caused quenching (ACQ) effect and restrict the vibration and motion of the guest molecules to suppress nonradiative relaxations.…”

Host–Guest Metal–Organic Frameworks-Based Long-Afterglow Luminescence Materials

“…Inorganic long-afterglow materials are composed of either transition metals compounds [6] or rare-earth metal compounds [7], mainly including rare-earth-doped aluminate [8,9], silicate [10][11][12], stannite [13], phosphate [14,15], gallate [16,17] and germanate [18,19], which usually require high-temperature calcination to obtain. Organic materials with long afterglows include carbon-based materials [20,21], organic dyes [22,23], polymer-based materials, [24][25][26][27], etc. However, it is the high cost and relatively complex synthesis that have limited the applications of those materials.…”