Vapor‐ and Mechanical‐Grinding‐Triggered Color and Luminescence Switches for Bis(σ‐fluorophenylacetylide) Platinum(II) Complexes

Square‐planar bis(σ‐fluorophenylacetylide) platinum(II) complexes [Pt(Me 3 SiCCbpyCC‐SiMe 3 )(CCC 6 H 4 F) 2 ] (CCC 6 H 4 F‐2 for 2 , CCC 6 H 4 F‐3 for 3 , and CCC 6 H 4 F‐4 for 4 ; Me 3 SiCCbpyCCSiMe 3 =5,5′‐bis(trimethylsilylethynyl)‐2,2′‐bipyridine) were prepared and were characterized by spectroscopic and luminescence studies, and X‐ray crystallography. The color and luminescence of crystalline complex 3 is specifically sensitive to CHCl 3 vapor to afford 140–180 nm of luminescence vapochromic redshift, which is useful for specific detection of CHCl 3 vapor. Complex 4 displays selective luminescence vapochromic properties to CH 2 Cl 2 and CHCl 3 vapors with a luminescence vapochromic shift response of ca. 150–200 nm. Interestingly, complexes 2 – 4 exhibit reversible, and naked‐eye perceivable, mechanical stimuli‐responsive color and luminescence changes. When solid species 2 – 4 are crushed gently or ground, the crystalline state is converted to an amorphous phase. Meanwhile, bright yellow‐orange luminescence in the crystalline species is converted to dark red under UV light irradiation with 100–160 nm of mechanochromic shift response. A vapochromic or mechanochromic cycle was monitored by dynamic variations in emission spectra and X‐ray diffraction (XRD) patterns. The halohydrocarbon vapor‐ or mechanical‐grinding‐triggered color and luminescence switches are most likely correlated to a shorted intermolecular Pt–Pt distance as that revealed in vapochromic species 4⋅ 0.5 CH 2 Cl 2 by X‐ray crystallography, thus leading to an increased contribution from intermolecular Pt–Pt interaction as demonstrated by DTF computational studies.