Thermo-, Mechano-, and Vapochromic Dinuclear Cuprous-Emissive Complexes with a Switchable CH₃CN–Cu Bond

Abstract

A thermo-, mechano-, and vapochromic bimetallic cuprous-emissive complex has been reported, and the origin and application of its tri-stimuli-responsive luminescence have been explored. As revealed by single-crystal structure analysis, thermoand vapochromic luminescence adjusted by heating at 60 °C and CH 3 CN vapor fuming, accompanied by a crystalline-to-crystalline transition, is due to the breaking and rebuilding of the CH 3 CN−Cu bond, as supported by 1 H nuclear magnetic resonance (NMR), Fourier-transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetry (TG), and time-dependent density functional theory (TD-DFT) analyses of the CH 3 CN-coordinated species 2). Luminescence mechanochromism, mixed with a crystalline-to-amorphous transition where the initial crystalline is different for 1 and 2, is mainly assigned as the destruction of the CH 3 CN−Cu bonding and/or the O•••HN dppa and OH•••N triazolyl hydrogen bonds. It is also suggested that a rational use of switchable coordination such as weak metal−solvent bonding is a feasible approach to develop multi-stimuli-responsive luminescent materials and devices.

Mechanochromic and Selective Vapochromic Solid-State Luminescence of a Dinuclear Cuprous Complex

“…As shown in Figure S5a, 1-g and 1-c in CH 2 Cl 2 show identical absorption and broad unstructured emission profiles, mainly stemming from the charge-transfer transitions, as suggested by TDDFT calculations of 1-g in CH 2 Cl 2 media (vide infra) and previously reported 1,2,4-triazole-based Cu­(I) phosphine systems. − Polymorphs 1-g and 1-c give a broad unstructured emission band peaking at 498 and 487 nm, respectively, blue-shifted by 37 and 48 nm relative to that (535 nm) in CH 2 Cl 2 (Figure S5b), which is ascribed to the rigid matrix. − As depicted in Figure c and Table S3, when 1-g is ground, a red-shifted emission occurs in ground 1-g (511 nm), which is mainly attributable to the breaking of NH bpmtzH ···OClO 3 – hydrogen bonds under grinding, decreasing the LUMO basically localized on bpmtzH and hardly affecting the HOMO composed of Cu­(I) and dppm and thus leading to a reduction of the HOMO–LUMO energy gap and a red-shifted emission. , Upon exposure of ground 1-g to CH 2 Cl 2 vapor, a blue-shifted emission similar to that of 1-g appears in reverted 1-g (498 nm), which is attributed to the rebuilding of NH bpmtzH ···OClO 3 – hydrogen bonds induced by CH 2 Cl 2 vapor, resulting in an increase in the HOMO–LUMO gap and blue-shifted emission. When exposure of 1-g to CHCl 3 vapor occurs, a cyan emission similar to that of 1-c appears in 1- g -c (484 nm), which is ascribed to the changes in NH bpmtzH ···OClO 3 – and intramolecular triazolyl/phenyl π···π interactions caused by different solvents, such as CH 2 Cl 2 and CHCl 3 , perhaps passing through CH solvent ···N bpmtzH hydrogen bonds.…”

Multistimuli-responsive behavior of a phosphorescent Cu3pyrazolate3complex for luminescent logic gates and encrypted information transformation

“…27 To date, although intriguing multi-responsive complexes based on platinum, gold, or other precious metals have been reported, 26,[28][29][30][31][32] Cu(I) complexes are still very promising candidates for low-cost multi-responsive materials. Examples include a tetranuclear Cu(I) complex showing luminescence mechanochromism and vapochromism triggered by the alternation of intramolecular π⋯π interactions, 33 a dinuclear Cu(I) complex showing luminescence thermo-, mechano-, and vapochromism relevant to a switchable CH 3 CN-Cu bond, 34 and a Cu(I) metal-organic framework for sensing temperature, solvents and nitro explosives. 35 Pyrazolate-based Cu(I) cyclic trinuclear complexes (CTCs) represent an important class in the family of coinage-metalbased CTCs, whose fascinating luminescence behaviors are often dominated by aggregation.…”

One-Dimensional Heterobimetallic Au/Ag Coordination Polymer Showing a Selective, Reversible, and Visible Vapor-Chromic Photoluminescent Response toward Methanol

“…Photoluminescent (PL) chemical sensing methods have the advantage of simplicity, portability, and sensitivity; − thus they have been widely developed for the detection of environmental pollutants. A group of poly-nucleated gold and silver complexes have attracted interest in this respect because their emissions are related to metal–metal–ligand charge transfer (MMLCT) , or ligand-to-metal–metal charge transfer , processes that are sensitive to external stimuli, resulting in vapor-chromic, − solvato-chromic, mechano-chromic, , pressure-chromic, and thermo-chromic − responses.…”