Bromonaphthalenes phosphorescence

Rothman, W., Case, A., Kearns, D. R. Determination of singlet-triplet absorption spectra from phosphorescence excitation spectra a-bromonaphthalene. J. Chem. Phys. 43, 1067 (1965). 

In addition to the sensors dealt with in Section 3.3.1.1, which could equally have been included in this Section as they use consumable immobilized reagents and regenerable fluorophores, Frei et al. developed a sensor for HPLC determinations based on the solid-state detection cell depicted in Fig. 3.38.B, where they immobilized 1-bromonaphthalene for measuring phosphorescence quenchers. Experiments demonstrated the sensor s usefulness for determining nitrate with a detection limit of ca. 10" M and an RSD of 4% for an analyte concentration of M. However, the scope of application of this sensor to chromatographically separated anions is rather narrow owing to the low sensitivity of the quenched phosphorescence detection for iodide and other halides [268]. 

Surfactants were found to induce phosphorescence from 1-bromonaphthalene in aerated aqueous solutions of (3-CD [22], In the case of the 1 1 inclusion-complex formation between 7-cyclodextrin and acenaphthene in aqueous solution, bromoalcohols such as 2,3-dibromopropane-l-ol or 2-bromoethanol induced a decrease of the fluorescence and an enhancement of room-temperature phosphorescence of acenaphthene [23],... 

Mortellaro et al. prepared two (3-CD derivatives, which have a bromonaph-thalene unit at the primary (1) and secondary OH groups (2) of (3-CD [27], The phosphorescence of 2 at 530 nm is more than 100 times intense than that observed for an equimolar solution of 1. These results suggest that the bromonaphthalene moiety of 2 is protected from oxygen quenching, being located inside the CD cavity, whereas the bromonaphthalne moiety of 1 is not protected, being exposed into bulk solution. 

De Silva et al. [28] prepared a naphthalene derivative (3) with logic functions (Scheme 1). Here, the bromonaphthalene unit exhibits phosphorescence in the presence of both the calcium ion and (3-CD [28], However, without them, oxygen quenches the phosphorescence of 2-bromonaphthalene phosphor because the protection effect of (3-CD is absent and photoinduced electron transfer from the tetracarboxylate receptor to the 2-bromonaphthalene phosphor occurs. Thus, phosphorescence output occurs only when the calcium ion and (3-CD inputs are active. The operation of these two inputs with a phosphorescence output corresponds to the AND logic function. The input to the NOT gate is oxygen. In the presence of oxygen without either calcium or (3-CD, the AND gate is disabled. 

Fig. 7. A three-input INHIBIT gate exemplified by the tetraanion 54 and /1-cyclodextrin (j8-CD). a With neither protons nor /1-CD present in the solution, phosphorescent output is low, because of both PET from the tertiary amine, and through intermolecular triplet-triplet collisions of the bromonaphthalene phosphor, b Addition of calcium ions leads to a reduction in the PET-based quenching of the phosphorescence - however, intermolecular collisions still lead to a low emission, c Shielding of the phosphor with /l-CD reduces intermolecular triplet annihilations, but quenching still occurs via PET. d Only with both Ca2+ and /1-CD present does the solution phosphoresce, e In any combination of Ca2+ and /1-CD, the solution will yield a low output in the presence of molecular oxygen (the INHIBIT stimulus), as a consequence of triplet-triplet collisions...

Phosphorescence was employed to study the dynamics of polycyclic aromatic hydrocarbons with SDS micelles [62]. Equation (25) was applied with the assumption that k i, is negligible. In the case of 1-bromonaphthalene, the val-... 

A variation of the quenching method leading to Eq. (25) is to follow the decay of the triplet state from the emission of a luminescent quencher, which is much more intense than the phosphorescence of the probe [192]. In this case, the observed rate constant corresponds to the growth and subsequent decay in the emission profile of the quencher. However, an additional rate constant, corresponding to the emission lifetime of the quencher, has to be included in Eq. (25). The exit rate constant was determined to be 2.5 x 10 s for 1-bromonaphthalene when quenched by either Eu or Tb. This value is the same (Table 16) as that determined using the anionic quencher, NOf [62], showing that this method is useful. However, care should be taken to eliminate the possibility of reverse energy transfer. 

TABLE 5 Quantum Yields and Lifetimes t of Phosphorescence aud Oxygen Quenching Rate Constants of 1-Bromonaphthalene-Glucosyl-p-CD-alcohol Complexes in Water ... 

The bromonaphthalenes, 56, have a pH-controlled phosphorescence. At pH lower than ground-state pA , the protonation of the amino group hampers the quenching of the bromonaphthyl moiety emission by the electron-transfer process. The addition of 5 x 10" P-CD caused a... 

A non-covalent sensory system based on phosphorescence was also described recently. The inclusion complex of 1-bromonaphthalene with p-cyclodextrin (58) shows room temperature phosphorescence in the presence of menthol enantiomers, due to the formatiOTi of ternary complexes with both menthol and 1-bromonaphthalene included. The phosphorescence lifetime was found to be different for the two enantiomers (4.28 0.06 and 3.71 0.06 ms for (—)-menthol and (-F)-menthol, respectively) due to the higher exposure to dissolved oxygen of the latter complex [123]. 

Garcia-Ruiz C, Scholtes MJ, Ariese F et al (2005) Enantioselective room temperatine phosphorescence detection of non-phosphorescent analytes based on interaction with P-cyclodextrin/l-bromonaphthalene complexes. Talanta 66 641-645... 

The triplet state has received rather less attention than the singlet in micellar photochemistry. Phosphorescent decay of solubilized polynuclear aromatic hydrocarbons from their Tj state may be observed in heavy-metal ion lauryl sulphate micelles. This involves a conventional intersystem crossing from Si- Ti promoted by spin-orbit coupling with the heavy atom. 1-Bromonaphthalene readily forms a triplet excited-state in micelles, which may be quenched by added sodium nitrite in water, the lifetime then being reduced from 2.8 x 10 s to 5 x 10 s. There is efficient triplet energy transfer from N-methylphenothiazine (Ti) to trans-stilbene (So), which is irreversible but reversible energy-transfer to naphthalene (So) occurs. ... 

This method is illustrated in Figure 2.7, which shows the variation of the phosphorescence decay rate of 1-bromonaph-thalene solubilized in sodium dodecylsulfate (SDS) micelles in the presence of an increasing concentration of sodium nitrite in the aqueous phase. The 1-bromonaphthalene triplet... 

Figure 2.7 Variation of the phosphorescence lifetime of 1-bromonaphthalene with the sodium nitrite concentration and at SDS concentration as indicated on the plots. Reproduced from reference 54 with permission of the American Chemical Society.

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