Strategic modification of ligands for remarkable piezochromic luminescence (PCL) based on a neutral Ir(iii) phosphor

Abstract

A neutral Ir(iii) complex has been synthesized by introducing a carboxyl group and fluorine substituents into the ligands to construct a new piezochromic luminescence (PCL) active material.

Recent Advances in Mechanochromism of Metal-Organic Compounds

“…Introducing halogen, or oxygencontaining functional groups into ligands is an important way to obtain mechanochromic complexes. Based on this strategy, R. Bryce et al rationally designed a neutral iridium (III) complex with reversible mechanochromism (Li et al, 2019). The carboxyl and electron-accepting F substituents were incorporated to form intermolecular interactions such as ππ interactions, C-H•••F and O-H•••O hydrogen bonds, which played a vital role to achieve the mechanochromism of the iridium (III) complex.…”

“…Mechanochromism, a subclass of smart stimuli-responsive materials, refers to the solid materials whose luminescent color or intensity can be changed under the stimulus of mechanical force. Mechanochromic materials have been widely used in data storage, information encryption and sensors due to their simple operation, obvious and fast response (Perruchas et al, 2010;Zhang et al, 2017;Seki et al, 2017;Ito et al, 2008;Song et al, 2018;Li et al, 2019;Zhu et al, 2020). The emission color of mechanochromic materials usually have wide luminous range, covering the entire visible region and even reaching in the near-infrared region (Seki et al, 2017;Zhang et al, 2021;Li et al, 2021).…”

“…Although the current research on mechanochromic metal-organic compounds is limited, such mechanochromic materials are still attractive and are expected to exhibit more interesting phenomena due to the metalophilic interactions existed in metal complexes. These mechanochromic phenomenons are thought to result from the crystalline-to-amorphous (CA) phase transformation, single-crystal-to-single-crystal (SCSC) phase transformation or triplet excited states transformation caused by the intermolecular conformational folding or twisting, as well as changes in intermolecular π-π, metalophilic or hydrogen-bonding interactions (Seki et al, 2013;Ito et al, 2013;Seki et al, 2015;Jin et al, 2017;Jin et al, 2018;Li et al, 2019;Pei et al, 2020;Xie et al, 2020). Indeed, an explicit mechanism has not been investigated yet because of the difficulty in characterizing the amorphous phase.…”

Development of Dual Phosphorescent Materials Based on Multiple Stimuli-Responsive Ir(III) Acyclic Carbene Complexes

“…Mechanoresponsive and multiple stimuli-responsive luminescent compounds, which can change their luminescent properties by external stimuli, including mechanical force, magnetic field, temperature, light, and chemical vapors, have important applications as luminescent smart materials. [1][2][3][4][5][6][7][8][9] These stimuli-responsive behaviors can be derived from intermolecular and/or intramolecular processes. [10][11][12] To date, most of the reported mechanoresponsive systems are mainly developed from the changes of intermolecular interactions such as π-π, hydrogen, dipole-dipole, metal-metal, and metal-ligand interactions associated with a crystalline to amorphous transition [13][14][15][16][17][18][19][20][21][22][23][24] or a change of the aggregation state.…”

Mechanofluorochromic Material toward a Recoverable Microscale Force Sensor

“…Light, [ 7–11 ] heat, [ 10,13–15 ] solvent (and its vapor), [ 16–18 ] and mechanical forces, [ 2,6,19–22 ] modify the structure of materials at the (supra)molecular level to effect changes in both absorption and emission properties. Among these stimuli‐responsive processes, mechanofluorochromism, [ 20–50 ] the change in optical properties upon application of mechanical stimuli such as scratching or grinding, promises applications for force sensors. [ 20–36 ] Emission changes of coordination complex crystals, [ 24 ] polymeric microcrystals, [ 30 ] and organic fluorophores, [ 31–36 ] have been correlated to an applied force or pressure for new anticounterfeiting technologies [ 23–28 ] and biological stress probes.…”