Protecting the triplet excited state in sterically congested platinum porphyrin

Abstract

Platinum tetrakis(2,4,6-triethylphenyl)porphyrin (Pt-1) was synthesized and its structural (X-ray), electrochemical and photophysical properties were fully characterized. Comparative studies of Pt-1 and its unsubstituted analog PtTPP show the effect of sterically congesting ortho-substituents on the dynamics of the triplet excited states. Lowered quenching rates by 3-4 times were observed for Pt-1vs. PtTPP in the presence of oxygen and perylene, and in concentration (self)-quenching experiments.

Carbazole-based polymers as hosts for solution-processed organic light-emitting diodes: Simplicity, efficacy

“…These complexes are highly versatile since neutral [7][8][9][10][11][12], cationic [13][14][15][16][17], anionic [18,19] but also soft salts [20,21], in which both the ion-paired anionic and cationic iridium complexes can participate to light emission, were successfully used as triplet emitters for OLEDs. These complexes also benefit from several appealing features including high quantum yield of luminescence [22,23], phosphorescence at room temperature [24] and relatively short excited state lifetimes so that key adverse factors such as triplet-triplet annihilation and back energy transfer from the guest to the host are strongly limited [25][26][27][28]. Emission color can also be easily tune by mean of the ligands introduced in the coordination sphere of the metal cation, enabling the emission to range from blue to red [29][30][31][32][33][34][35].…”

Protection of densely populated excited triplet state ensembles against deactivation by molecular oxygen

“…Decreasing triplet excited state quenching rates by means of a steric congestion caused by the introduction of bulky alkylgroups around phosphorescent platinum porphyrin ( Fig. 12) was reported by Moiseev et al 59 The comparison with the known platinum tetraphenylporphyrin PtTPP demonstrated the role of the substituents in suppressing quenching of the triplet excited states: the bimolecular rates for oxygen quenching k O 2 of PtTTEPP and PtTPP triplet excited states were calculated to be 4.1 Â 10 8 M À1 s À1 and 14.8 Â 10 8 M À1 s À1 , respectively.…”

Visible-Light Initiated Free Radical Polymerization by Homomolecular Triplet-Triplet Annihilation

“…Immediately following the laser pulse, the excited state absorption band (T1→Tn) 59,60 appeared at 465 nm, which is attributed to 3 ZnTPP * . [61][62][63] Interestingly, the magnitude of the prompt 3 ZnTPP * transient features experienced negligible changes as a function of TMPTA concentration.…”