Effect of Gold(I) on the Room‐Temperature Phosphorescence of Ethynylphenanthrene

Abstract

The synthesis of two series of gold(I) complexes containing the general formulae PR 3 ‐Au‐C≡C‐phenanthrene (PR 3 = PPh 3 ( 1a / 2a ), PMe 3 ( 1b / 2b ), PNaph 3 ( 1c / 2c )) or (diphos)(Au‐C≡C‐phenanthrene) 2 (diphos = 1,1‐ bis (diphenylphosphino)methane, dppm ( 1d / 2d ); 1,4‐ bis (diphenylphosphino)butane, dppb ( 1e / 2e )) have been synthesized. The two series differ on the position of the alkynyl substituent on the phenanthrene chromophore, being at the 9‐position (9‐ethynylphenanthrene) for the L1 ‐series and at the 2‐position (2‐ethynylphenanthrene) for the L2 ‐series. The compounds have been fully characterized by 1 H and 31 P NMR and IR spectroscopy, mass spectrometry and single crystal X‐ray diffraction resolution in the case of compounds 1a , 1e , 2a , and 2c . The emissive properties of the uncoordinated ligands and corresponding complexes have been studied in solution and within organic matrixes of different polarity (PMMA and Zeonex). We have observed room temperature phosphorescence (RTP) for all gold(I) complexes while only fluorescence can be detected for the pure organic chromophore. In particular, the L2 ‐series present better luminescent properties regarding intensity of emission, quantum yields and RTP effect. Additionally, while the inclusion of all the compounds in organic matrixes induces an enhancement of the observed RTP due to the decrease in non‐radiative deactivation, only the L2 ‐series completely supress fluorescence giving rise to pure phosphorescent materials.