Photophysics and Electrochemistry of some Thione Far-Red/Near-IR Triplet Emitters

Abstract

The photophysics and cyclic voltammetry of two novel phosphorescent thiones, 2,2-dimethyl-indan-1-one-3-thione (DMIKT) and 2,2-dimethyl-indan-1,3-dithione (DMIDT), and three known phosphorescent thiones, 4H-pyran-4-thione (PT), 4H-1-benzopyran-4-thione (BPT) and 2,2-dimethylindan-1-thione (DMIT), have been characterised and compared. The phosphorescence emission of DMIT, DMIKT and DMIDT extends from the red into the near-IR spectral region. The additional carbonyl or thione group of DMIKT and DMIDT causes a significant shift in the emission maxima to 680 nm compared to that of DMIT, at 637 nm, in perfluorinated hydrocarbons. In acetonitrile the emission maxima of DMIKT and DMIDT are at 696 and 706 nm, respectively, and the spectra show vibronic bands which extend out beyond 850 nm. There is a significant reduction in triplet lifetime along this series (from 44 (+/-2) micros (DMIT) to 10 ((+/-0.8) micros (DMIKT) in perfluorinated solvents, and 8.6 (+/-0.5) (DMIT), 1.3 (+/-0.5) (DMIKT) and 0.35 (+/-0.07) micros (DMIDT) in acetonitrile), as well as a reduction in the rate constant for ground-state quenching of the triplet, (from 9.8 ((+/-0.9) to 3.5 ((+/-0.6) and 1.3 ((+/-0.2)x10(9) mol(-1) dm3 s(-1) for the same compounds). The addition of the C=O or C=S groups also causes a decrease in phosphorescence quantum yield with the highest emission quantum yield obtained for DMIT (PhiP=0.149 (+/-0.015)). Electrochemical studies show that while PT and BPT exhibit irreversible redox behaviour, DMIT, DMIKT and DMIDT all show at least one reversible reduction wave attributed to a one-electron process centred on the C=S moiety. The suitability of these lumophores for use in OLEDs is discussed.

Spectroscopic and electrochemical characterization of gold(I) and gold(III) complexes with glyoxaldehyde bis(thiosemicarbazones): cytotoxicity against human tumor cell lines and inhibition of thioredoxin reductase activity

“…The successive cathodic steps observed in the cyclic voltammogram of all compounds may be assigned to reduction processes centered on the C=S moiety as previously reported in the literature (Evans et al 2009;Zhang et al 1995).…”

Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions

“…3 , solid black line). In particular, as reported in [ 37 ] about the electrochemical properties of some thiones, the redox process involving the thionucleoside could be attributable to an electron transfer process centered on the C=S moiety.…”

Dual Emission: Classes, Mechanisms, and Conditions

“…[75a, 80] However,t hey exhibit low F F values, [80,81] as ar esult of fast nonradiative decay from S 1 via aC I, so that the F F value of MG greatly increases in rigid environments. [82] Conceptually interesting are thioketones, [67] as they allow non-Kasha FL to be merged with PH. Arecent example with balanced DE (however, alow total quantum yield F F + F P )is a7 -methoxyindanthione derivative (DM-7MIT;s ee Figure 4).…”