Vapochromism and vapoluminescence of platinum(II) 3,8-bis-(3-hydroxy-3-methylbut-1-yn-1-yl)-phenanthroline organometallic complexes with bis-arylethynyl derivatives

A new series of platinum(II) organometallic complexes with 3,8-bis-(3-hydroxy-3-methylbut-1-yn-1-yl)-1,10-phenanthroline (3,8-Phen equivalent to-C(CH3)(2)OH) and nine respective arylethynyl ligands with different substituents (Pt(3,8-Phen equivalent to-C(CH3)(2)OH)(equivalent to Ph-R-2)(2): R-2 = H (1OH), 2-F (2OH), 3-F (3OH), 4-F (4OH), 4-Me (5OH), 4-CF3 (6OH), 4t-Bu (7OH), 3,5-di-CF3 (8OH), 3,5-di t-Bu (9OH)) were synthesized and their luminescences in solution and solid state were characterized by photoluminescence spectroscopy. The luminescence of each of the new complexes, 1OH - 9OH, in solution was assigned to the phosphorescence from the mixed transition of (MLCT)-M-3/(LLCT)-L-3 (LLCT = ligand-to-ligand charge transfer), revealing that two series had very similar emission spectra: Pt(3,8-Phen equivalent to TMS)(-equivalent to Ph-R)(2) 1TMS - 9TMS and Pt(3,8-Phen equivalent to H)(equivalent to Ph-R)(2) 1H - 9H in solution. In solid state, the emission spectra of three series of platinum organometallic complexes, 1OH - 9OH, 1H - 9H , and 1TMS - 9TMS, were observed over a wide range (500-1100 nm) because the phosphorescence of each of these complexes was assigned to the emission from the (MLCT)-M-3/(LLCT)-L-3 mixed transition and/or the transition of a metal-metal-to-ligand charge transfer, called 3MMLCT. Results of vapochromism and vapoluminescence experiments with 13 species of volatile organic compounds (VOCs) for three series of the 27 above-mentioned platinum complexes suggested that the vapochromism of the present complex systems was induced by sterically hindered substituents of the arylethynyl ligands as tert-butyl substituents, and that the expansion of the space among the molecules in solid state is important for selective and multicolor detection with vapochromism and vapoluminescence for VOCs. Especially, the vapoluminescence experiment with VOCs for 9TMS, which was composed of a combination of the bulkiest ligands, 3,8-bis-(trimethylsilyl)ethynyl-1,10-phenanthroline and 3,5-di-t-butyl-phenylehtynyl ligands, among the present 27 complexes showed multicolor changes from yellow to dark brown, in contrast with respective VOCs. (C) 2020 Elsevier B.V. All rights reserved.