Vapochromic and Mechanochromic Phosphorescence Materials Based on a Platinum(II) Complex with 4-Trifluoromethylphenylacetylide

Abstract

Planar platinum(II) complex Pt(Me(3)SiC≡CbpyC≡CSiMe(3))(C≡CC(6)H(4)CF(3)-4)(2) (6) with 5,5'-bis(trimethylsilylethynyl)-2,2'-bipyridine and 4-trifluoromethylphenylacetylide exhibits remarkable luminescence vapochromic and mechanochromic properties and a thermo-triggered luminescence change. Solid-state 6 is selectively sensitive to vapors of oxygen-containing volatile compounds such as tetrahydrofuran (THF), dioxane, and tetrahydropyrane (THP) with phosphorescence vapochromic response red shifts from 561 and 608 nm to 698 nm (THF), 689 nm (dioxane), and 715 nm (THP), respectively. Upon being mechanically ground, desolvated 6, 6·CH(2)Cl(2), and 6·(1)/(2)CH(2)ClCH(2)Cl exhibit significant mechanoluminescence red shifts from 561 and 608 nm to 730 nm, while vapochromic crystalline species 6·THF, 6·dioxane, or 6·THP affords a mechanoluminescence blue shift from 698 nm (THF), 689 nm (dioxane), or 715 nm (THP) to 645 nm, respectively. When the compounds are heated, a thermo-triggered luminescence change occurs, in which bright yellow luminescence at 561 and 608 nm turns to red luminescence at 667 nm with a drastic red shift. The multi-stimulus-responsive luminescence switches have been monitored by the changes in emission spectra and X-ray diffraction patterns. Both X-ray crystallographic and density functional theory studies suggest that the variation in the intermolecular Pt-Pt interaction is the key factor in inducing an intriguing luminescence switch.

Recent Advances in Phosphorescent Pt(II) Complexes Featuring Metallophilic Interactions: Properties and Applications

“…PMMA was also employed by Chen and co-workers to obtain a device acting as a logic gate with mechanical and vapor based stimuli. 76 By using platinum complexes, bearing 4-trifluoromethylacetylide ligands, such as 17 in Chart 2, they were able to fabricate a proof-of-principle device that can be considered as an example of multistate logic gate (Figure 15). The device relies on the ability of Pt complexes to undergo not only the transition from absence to presence of metallophilic interactions, but also other transitions among structures showing different Pt£Pt distances.…”

Vapochromic Platinum(II) Complexes: Crystal Engineering toward Intelligent Sensing Devices

“…Such intermolecular hydrogen bonds might suppress the vapor uptake. Considering the fact that several interesting vapochromic Pt II complexes have been recently developed by utilizing hydrophobic–hydrophobic interactions,44–47 this interaction would be one of the most useful interactions to design vapochromic materials based on the Pt II chromophores.…”

Aggregation and Tunable Color Emission Behaviors of l‐Glutamine‐Derived Platinum(II) Bipyridine Complexes by Hydrogen‐Bonding, π–π Stacking and Metal–Metal Interactions

“…Upon excitation at λ >400 nm, all complexes showed strong emission properties in degassed chloroform solutions with emission quantum yields of 0.31–0.74. According to previous reports, the structureless emission bands with peaks at 537–568 nm were assigned as originated from 3 MLCT [dπ(Pt)→π*(bpy)] excited state with some mixing of 3 LLCT [π(C≡C)→π*(bpy)] character (Figure b). An emission tail was observed for complex 1 at λ >650 nm in dilute chloroform solution, which is indicative of its strong tendency to aggregate and is in line with the indistinctive 1 H NMR signals in spectra recorded even under dilute conditions.…”