Triplet emissions

Lu, W., Li, Y, Chan, M.C.W., Che, C.-M., Cheung, K.-K and Zhu, N. (2002) Organic triplet emissions of arylacetylide moieties harnessed through coordination to [Au(PCy3)]. Effect of molecular structure upon photoluminescent properties. Journal of the American Chemical Society, 124,14696-14706 (c) Lu, W., Zhu, N. and Che, C.M. (2003) Polymorphic forms of a gold(I) arylacetylide complex with contrasting phosphorescent characteristics. Journal of the American Chemical Society, 125, 16081—16088 ... 

In the absence of capping ligands, polymeric alkynylmercury derivatives can be readily prepared. Polymer 57 is formed by reaction of HgC with 9,9-bis(4-ethynylphenyl)-fluorene in a basic methanolic solution. This polymer, whose average molecular weight (/I7W) is only 8,900, shows a strong triplet emission of the organic chromophore enhanced by the presence of the mercury heavy atom.69... 

For a triplet emissive guest (phosphorescent) dopant, the triplet energy level of the host normally should be higher than that of the guest. 

An increase in the ion annihilation exergonicity AG to values comparable to the excited triplet-state energies (AG I LT < 0) opens an additional electron transfer channel (T-route). In the simplest case, only one excited triplet 3 A or 3 D becomes accessible. Triplet emission can be directly observed from the ECL systems involving rare earth and transition metal complexes with allowed (due to extensive spin-orbit coupling) triplet-singlet electronic transition. 

Luminescence quenching of the zinc-substituted cytochrome c (Zn-cyt c) excited state by cytochrome b5 (cyt b5) has been investigated97. The most striking result of the quenching study is that the triplet emission decay rate of Zn-cyt c (3k = 102 s ) is remarkably accelerated in Zn-cyt c/cyt b5 (3k = 5 x 105 s-1) by about a factor of... 

The optical and PL spectroscopies have been undertaken to understand the structure-property correlations of this important family of triplet-emitting polymers. The red shift in the absorption features upon coordination of the metal groups is consistent with there being an increase in conjugation length over the molecule through the metal center. The trade-olf relationship between the phosphorescence parameters (such as emission wavelength, quantum yield, rates of radiative and nonradiative decay) and the optical gap will be formulated. For systems with third-row transition metal chromophores in which the ISC efficiency is close to 100%,76-78 the phosphorescence radiative (kr)y, and nonradiative (/cm)p decay rates are related to the measured lifetime of triplet emission (tp) and the phosphorescence quantum yield ([Pg.300]

By changing from a trans- to a m-con figured Pt(II) unit (i.e., from 21 to 75), the conjugation chain in 75 is disturbed (Xmax=364 nm for 75 versus 391 nm for 21), resulting in a much stronger triplet emission at room temperature (Fig. 9).32,33 However, the solubility of 75 notably decreases relative to 21, resulting in a lower molecular weight for the soluble fraction of the polymer. 

A new family of Pt(II) polyyne polymers functionalized with substituted 1,4-diethynylbenzene derivatives 8—14 were synthesized and optically characterized by absorption and PL studies.20 In regard to the emission properties, it is interesting to see that the relative intensity of triplet emission increases strongly with the electronegative fluorine content in such system. 

The triplet emission can be totally suppressed by adding an efficient quencher, e.g., 1,3,5-hexatriene 560>. 

Orthometalated Ir complexes are known to have highest triplet emission quantum yields due to several factors [109,110] ... 

Excitation of room temperature deaerated solutions of selected heterocyclic-substituted platinum-1,2-enedithiolates leads to a dual emission, which is characteristic of this class of molecules (Fig. 3) (17-19, 22-24, 29-31). As can be seen in Fig. 3, the triplet emission is diffusionally quenched by oxygen while the singlet emission is insensitive to oxygen. 

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