RESUMEN
Based on benzo[i]dipyrido[3,2-a:2',3'-c]phenazine (dppn) with photo-oxidation activity, complexes [Ir(pbt)2(dppn)]Cl (1) and [Ir(pt)2(dppn)]Cl (2) have been synthesized (pbtH = 2-phenylbenzothiazole, and ptH = 2-phenylthiazole), with two aims, including studying the influence of the cyclometalating ligands (pbt- in 1, pt- in 2) on the photo-oxidation activity of these complexes and exploring their photo-oxidation-induced luminescence. Both 1H nuclear magnetic resonance (NMR) and electrospray (ES) mass spectrometry indicate that the benzo[g]quinoxaline moiety in complex 1 can be oxidized at room temperature upon irradiation with 415 nm light. Thus, this complex in CH2Cl2 shows photo-oxidation-induced turn-on yellow luminescence. In contrast, complex 2 reveals significant structural decomposition during the process of photo-oxidation due to incorporating a cyclometalating ligand pt- instead of pbt- in complex 1. In this paper, we report the photo-oxidation behaviors and the related luminescence modulation in 1 and 2 and discuss the relationship between structure and photo-oxidation activity in these complexes.
RESUMEN
Complexes [Pt(dfppy)(pbdtmi)]PF6 (1) and [Pt(ppy)(pbdtmi)]PF6 (2) have been constructed based on dithienylethene-based N^N ligand pbdtmi, showing supramolecular dimer structure in which two coordination cations connect each other through πâ¯π stacking interaction. The crystalline state samples of both 1 and 2 reveal strong phosphorescence (emission peak: around 579 nm for 1, and 551 nm for 2). Interestingly, a grinding treatment for either 1 or 2 leads to phosphorescence switching from on-state to off-state. The subsequent crystallization with toluene recovers the initial on-state. This work discusses the relationship between the supramolecular dimer structures and the related phosphorescence switching behaviors in 1 and 2, and also explores the photochromism of pbdtmi, 1 and 2.
RESUMEN
Two anthracene-based complexes [Ir(pbt)2(aip)]Cl (1) and [Ir(pbt)2(aipm)]Cl (2) have been synthesized based on the ligands aip = 2-(9-anthryl)-1H-imidazo[4,5-f][1,10]phenanthroline, aipm = 2-(9-anthryl)-1-methyl-imidazo[4,5-f][1,10]phenanthroline, and pbtH = 2-phenylbenzothiazole in order to explore both the influence of the substituent group R1 (R1 = H in 1 and CH3 in 2) on photo-oxidation activity and photo-oxidation-induced luminescence. Both 1H NMR spectra and ES mass spectra indicate that the anthracene moiety in complex 1 can be oxidized at room temperature upon irradiation with 365 nm light. Thus, this complex shows photo-oxidation-induced turn-on yellow luminescence. Compared to 1, complex 2 incorporates an R1 = CH3 group, resulting in very weak photo-oxidation activity. On the basis of experimental results and quantum chemical calculation, we report the differences between 1 and 2 in both photo-oxidation behavior and the related luminescence modulation and discuss the relationship between photo-oxidation activity and substituent group R1 in these complexes.
RESUMEN
Complex [Ir(dfppy)2(phca)]PF6 (1) has been synthesized, which contains an aldehyde group in the N^N ligand phca = 1,10-phenanthroline-4-carbaldehyde, with the aim of exploring solvent-driven luminescence modulation/switching in this complex. Complex 1 shows green emission at 514 nm in CH3OH, while orange phosphorescence with the emissions at 516 and 624 nm in CH2Cl2. The solid-state structure of 1 is dependent on the crystallization solvent used, forming a red solid 1R in CH2Cl2, while a yellow solid 1Y in CHCl3. The neighboring [Ir(dfppy)2(phca)]+ cations in solid 1R are held together by ππ stacking interactions, while by van der Waals interactions in solid 1Y. The distinct packing structures of 1R and 1Y lead to their significantly different solid-state luminescence, weak orange phosphorescence for 1R (emission at 620 nm, Φ = 3.3%) and strong yellow phosphorescence for 1Y (emissions at 532 and 558 nm, Φ = 46.6%). Both 1R and 1Y show CH2Cl2/CHCl3-driven phosphorescence switching between orange and yellow, due to their structural interconversion through recrystallization. Moreover, the emission color of 1Y can be reversibly switched between yellow and orange through alternate pressing and recrystallization in CHCl3. This work discusses the relationship among the solvent, the structure and the luminescence modulation/switching of complex 1.