Mechanochromic luminescence properties of fluoro-substituted pinene-containing cyclometalated platinum() complexes with multiple triplet excited states

• Published in: Dalton transactions : an international journal of inorganic chemistry 2021-06, Vol.5 (25), p.8938-8946
• Main Authors: Yang, Qian-Ying, Zhang, Hua-Hong, Qi, Xiao-Wei, Sun, Shi-Shu, Zhang, Da-Shuai, Han, Li-Zhi, Zhang, Xiao-Peng, Shi, Zai-Feng
• Format: Article
• Language: English
• Subjects: Crystallography; Dichloromethane; Excimers; Excitation; Luminescence; Mechanoluminescence; NMR; Nuclear magnetic resonance; Optical properties; Performance degradation; Perturbation
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d1dt00848j

The structure-mechanochromism relationship is explored with respect to packing patterns and corresponding intermolecular interactions that are affected by the number and location of -F. The distinct and reversible mechanochormic luminescence (Δ λ em up to ca. 90 nm) of yellow solids (−)-1-Y g , (−)-2-Y g , and (−)-3-Y g was displayed with a simultaneous crystal-to-amorphous transformation. The change of multiple triplet excited states accounted for the mechanochormic luminescence, and a switch from the 3 π,π* monomer to the excimer/ 3 MMLCT occurred in the grinding process. The mechanical force led to perturbation in the molecular packing, and aggregates with effective Pt Pt and π-π interactions were formed in the amorphous phase, leading to the variation of excited states. The mechanochromic luminescence could be reverted by dropping in CH 2 Cl 2 and could be cycled multiple times without perceivable performance degradation. This work gives a reference for designing mechanochromic luminescent materials toward multicolor and multicomponent responses. The distinct and reversible mechanochormic luminescence of as-prepared yellow solids of (−)-2 are displayed. The interplay of 3 π,π* monomer and excimer/ 3 MMLCT excited states is supposed to be the key for mechanochromic luminescence.