Brightening Blue Photoluminescence in Nonemission MOF‐2 by Pressure Treatment Engineering

Abstract

As equally essential as the synthesis of new materials, maneuvering new structure configurations can endow the brand‐new functional properties to existing materials, which is also one of the core goals in the synthesis community. In this respect, pressure‐induced emission (PIE) that triggers photoluminescence (PL) in nonemission materials is an emerging stimuli‐responsive smart materials technology. In the PIE paradigms, harvesting bright PL at ambient conditions, however, has remained elusive. Herein, a remarkable PIE phenomenon is reported in initially nonemission Zn(BDC)(DMF)(H2O) (MOF‐2), which shows bright blue‐emission at 455 nm under pressure. Intriguingly, the bright blue PL with an excellent photoluminescence quantum yield up to 70.4% is unprecedentedly retained to ambient conditions upon decompression from 16.2 GPa. The detailed structural analyses combined with density functional theory calculations reveal that hydrogen bonding cooperativity effect elevates powerfully the rotational barrier of the linker rotor to 3.87 eV mol−1 from initial 0.91 eV mol−1 through pressure treatment. The downgrade rotational freedom turns on PL of MOF‐2 after releasing pressure completely. This is the first case of harvesting PIE to ambient conditions. These findings offer a new platform for the creation of promising alternatives to high‐performance PL materials based on initially nonemission counterparts.

Negative linear compressibility and strong enhancement of emission in Eu[Ag(CN)2]3·3H2O under pressure

“…The behaviour of the red shifts is mainly related to the expansion of the 4f orbital of Eu 3+ under high pressure. 43–45 We monitored the shifts of the emission peaks as shown in Fig. S6 (ESI†).…”

Dynamically responsive photonic metal–organic frameworks

“…In addition, the same group found that a nonemission MOF-2 and YðBTCÞðH 2 OÞ 6 also exhibit pressureresponsive photoluminescence. 127,128 Moggach et al also reported pressure-induced photoluminescence of Hf-peb MOF due to the linker rotation. 129…”

Proton-induced switching of excitation-wavelength-dependent emission based on mixed-ligand metal–organic frameworks

“…Stimuli-responsive luminescent materials, which can exhibit changes in optical properties under diverse physical/chemical stimuli such as light, pH, mechanical force, and temperature, have huge application potential in biological imaging, fluorescent sensors, data encryption, and anti-counterfeiting. 1–9 Among these responsive materials, excitation-wavelength-dependent (Ex-De) systems have gained particular interest because their tunable luminescence can be achieved by simply adjusting the excitation energy with fast, convenient, sensitive, and noninvasive manipulation features. 10–15 To date, various Ex-De systems have been widely developed, including carbon nanoparticles, organic molecules, metal complexes, and polymers, showing intrinsic advantages of high bio-compatibility, excellent processing properties and low cost.…”