Effect of alkyl chain length on the luminescence on-off mechanochromic behavior of solid-state Gold(I) isocyanide complexes

• Published in: Dyes and pigments 2018-03, Vol.150, p.315-322
• Main Authors: Dong, Yu-Bao, Chen, Zhao, Yang, Lan, Hu, Yu-Xuan, Wang, Xiao-Yan, Yin, Jun, Liu, Sheng Hua
• Format: Article
• Language: English
• Subjects: Alkyl chain length; Gold(I) isocyanide complex; Grinding; Luminescence on-off; Reversible mechanochromism
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2017.12.030

Five phenylethyne(p-alkoxyphenyl isocyanide)gold(I) complexes with different alkyl chains (OR) in the para-position of the phenyl isocyanide have been successfully synthesized [where R = CH3 (5a), C2H5 (5b), C4H9 (5c), C6H13 (5d), and C10H21 (5e)] and structurally characterized by 1H NMR, 13C NMR, and HRMS. To our surprise, the as-prepared powders of these complexes exhibited different emission colors. The diversity of their mechanochromic luminescence properties has been investigated with photoluminescence spectroscopy, powder X-ray diffraction (XRD) analysis, and single-crystal XRD analysis. The results indicated the presence of weak intermolecular interactions in their crystal structures, and different alkyl chains had obvious impacts on their stacking arrangements and optical behavior. The luminescence quantum yield of 5c was as high as 49.3% in the solid state. Complexes 5a–5e each showed luminescence quenching after grinding. Five phenylethyne(phenyl isocyanide)gold(I) complexes with different para-substituted alkyl chains (OR) were synthesized. These compounds show quite different fluorescence color in solid state which are due to different alkyl chain lengths. Surprisingly, all of them show luminescence on-off mechanochromism. [Display omitted] •Five phenylethyne(phenyl isocyanide)gold(I) complexes have been synthesized by several steps.•Unlike the traditional mechanochromic materials, these compounds show luminescence-off after grinding.•Four of them exhibit reversible mechanochromic luminescence in the solid state.•5c shows a high fluorescence quantum yield of 49.3%, which is a promising candidate in the field of photoelectronic devices.