Two Anthracene-Based Ir(III) Complexes [Ir(pbt)₂(aip)]Cl and [Ir(pbt)₂(aipm)]Cl: Relationship between Substituent Group and Photo-oxidation Activity as Well as Photo-oxidation-Induced Luminescence

Abstract

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 R 1 (R 1 = H in 1 and CH 3 in 2) on photo-oxidation activity and photo-oxidation-induced luminescence. Both 1 H 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 photooxidation-induced turn-on yellow luminescence. Compared to 1, complex 2 incorporates an R 1 = CH 3 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 R 1 in these complexes.

Benzo[g]quinoxaline-Based Complexes [Ir(pbt)2(dppn)]Cl and [Ir(pt)2(dppn)]Cl: Modulation of Photo-Oxidation Activity and Light-Controlled Luminescence

“…Complexes 1 and 2 in CH 2 Cl 2 reveal extremely weak luminescence at room temperature (Figure S25), which can be due to luminescence quenching resulting from intraligand (IL) charge transfer from the benzo­[ g ]­quinoxaline moiety to the phenanthroline moiety in a dppn ligand. , Interestingly, upon irradiation with 415 nm light, complex 1 in CH 2 Cl 2 shows a gradual increase in luminescence intensity, with two main emission bands at 531 and 560 nm (Figure ). This is due to the photo-oxidation of the benzo­[ g ]­quinoxaline moiety in complex 1 , i.e., the formation of the corresponding photo-oxidation species 1-O (Figure ) shows a relatively strong luminescence.…”

“…We have synthesized complexes [Ir(pbt) 2 (dppn)]Cl (1) and [Ir(pt) 2 (dppn)]Cl (2), which incorporate the same dppn ligand with photo-oxidation activity but different cyclometalating ligands pbt − and pt − . Both 1 and 2 show photooxidation activities, in which the dppn ligands can undergo photo-oxidation upon irradiation with 415 nm light at room temperature.…”

“…Thus, a benzo­[ g ]­quinoxaline derivative is expected to reveal similar physical and chemical properties to anthracene, for example, [4π + 4π] photodimerization and photo-oxidation (Scheme ). , Rakotomalala et al reported two 2,3-diarylbenzo­[ g ]­quinoxaline compounds (Scheme S1), 2,3-diphenylben-zo­[ g ]­quinoxaline (PhB) and 2,3-dipyridylbenzo­[ g ]­quinoxaline (PyB). They reveal a [4π + 4π] photodimerization property upon irradiation with 350 nm light .…”

Two cyclometalated Pt(ii) complexes showing reversible phosphorescence switching due to grinding-induced destruction and crystallization-induced formation of supramolecular dimer structure

“…It is well known that intraligand (IL) charge transfer can result in luminescence quenching in some metal complexes. 33 The crystalline samples of 1 and 2 are luminescent, mainly due to the fact that their dimer structures invalidate the intraligand (IL) charge transfer from pyridine–imidazole moiety to thiophene unit in ligand pbdtmi. 34 These dimer structures can be destructed by grinding treatment, thus the intraligand (IL) charge transfer can fluently occur in the grinding samples 1g and 2g, and leading to luminescence quenching ( Fig.…”