Anthracene fluorescence

GC of aqueous simulant or water extract of olive oil using cold on-column injector. 1,4 butane diol internal standard Solvent extraction with dichloromethane and concurrent derivatisation with 9-(methylaminomethyl)anthracene. Fluorescent derivatives analysed by HPLC with fluorescence detection... 

Figure 1. Representative anthracene fluorescence profile during the photosensitization of diaryliodonium salts in pure propanol at 30°C.

A plot of the anthracene fluorescence intensity at 425 nm as a function of the reaction time is shown in Figure 2. Again, this figure exhibits the effect of the instrumental artifact in the initial fluorescence data however, examination of the final 90% of the profile reveals that the anthracene concentration profile closely follows a first order exponential decay. Although the photosensitization reaction is bimolecular, the anthracene concentration follows a pseudo-first-order profile since the initiator is present in excess (i.e. r = = kjCA where r, Q and CA represent... 

Figure 2. Profile of anthracene fluorescence at 425 nm obtained during photosensitization of diaryliodonium salt in pure propanol at 30°C.

Comparison of the Experimental and Simulation Results. The preceding discussion has shown that both the experimental anthracene fluorescence profiles and the simulated anthracene concentration profiles decrease in a manner which closely follows an exponential decay. Therefore, the most convenient way to compare the simulation results to the experimental data is to define an effective overall photosensitization rate constant, kx or k2, as described above. Adoption of this lumped-parameter effective kinetic constant allows us to conveniently and efficiently compare the experimental data to the simulation results by contrasting the rate constant obtained from the steady-state fluorescence decay with the value obtained from the simulated decrease in the anthracene concentration. 

The intensity of anthracene fluorescence from liquid methyl methacrylate was examined over a wide range of concentrations. The fluorescence intensity measured following excitation at 350 nm was observed to be linear with anthracene concentration up to a mass fraction of 3 x 10 % anthracene in MMA. Experimental measurements were made with this concentration of anthracene in the liquid component of the cement. Fluorescence spectra... 

Incubation of Pseudomonas putida with anthracene-labeled carbon-base ferrichrome analog Fe(lll) complex 173 resulted in cellular iron uptake and the appearance of anthracene fluorescence in the culture medium identical to the Fe-ferrichrome uptake. Incubation with the alanyl analog 174 failed to show any significant iron uptake or fiuorescence. This is consistent with the tests described above on the unlabeled analogs. Remarkably, other strains such as Pseudomonas fluorescens S680 or WCS3742 also did not show any iron uptake or culture fluorescence. 

The most recent work210 on sensitized decomposition of peroxides dealt primarily with ketones (cf. Section III.C.3) although it was also demonstrated that anthracene could sensitize decomposition of benzoyl peroxide. In view of the earlier work206,209 and the fact that benzoyl peroxide quenches anthracene fluorescence at a rate of 1.0 x 1010M 1 sec-1 in benzene,211 a singlet exciplex mechanism is strongly implicated. 

Interesting examples are found in substituted anthracenes. The lifetimes and quantum yields of fluorescence of substituted anthracenes show different dependencies on temperature. The position of the substituent is more important than its nature. For 9- and 9,10-substituted anthracenes, fluorescence quantum yields increase steeply with decrease of temperature, while side-substituted derivatives have low yield and small temperature dependence. The variation is of the form... 

Values of Ar5xlO-1o for anthracene fluorescence A for Oa quenching, B for concentration quenching, C calculated from equation (6.4). 

Quenching of anthracene fluorescence from decay kinetics1 ... 

Stevens401 irradiated anthracene, 9-phenylanthracene, and 9,10-diphenylanthracene at 3600 A and 280-300°C. He found that both 02 and NO quenched the fluorescence with similar efficiencies. For anthracene at 280°C and 9-phenylanthracene at 300°C, the ratios of the quenching rate constant for NO to the fluorescence rate constant are, respectively, 1120 and 1380 M 1. Ware and Cunningham4384 found the rate constant to be 1.97 x 1011 M 1 sec-1 for the quenching of anthracene vapor by NO at 280°C. They also found the anthracene-fluorescence constant to be 3.51 x 107 sec-1. The ratio of their two rate constants is 5500 M-1, about a factor of five larger than that found by Stevens. 

TABLE 5 Deactivation of Singlet and Triplet Excited Linked Anthracenes. (Fluorescence Quantum Yields < >F in Cyclohexane. Reaction Quantum Yields < >R in Benzene)... 

Figure 28.15 a, Chemiluminescence spectrum obtained from electrolysis of a DMF solution containing 1 mM fluoranthene and 1 mAf 10-MP. Alternating steps at-1.75 V and +0.88 V vs. SCE were used, b, Chemiluminescence spectrum under the same conditions, but with 1 mM anthracene added. Inset shows anthracene fluorescence spectrum for a 10-5 M DMF solution. Reabsorption reduces the 0,0 intensity in b. [From Ref. 99, adapted with permission.]... 

The effect of solvent on fluorescence yields is still imperfectly understood. Mulliken-type interactions of the excited state with the solvent are believed to reduce yields (8). It has been stated in the literature that anthracene fluorescence falls through the solvent series benzene, toluene, xylene, and mesitylene, but recent measurements show that the effect, if any, is insignificant (42,59,64). For the two solvents, ligroine and chloroform, anthracene is much less fluorescent in the latter, but for 9,10 dichloranthracene the order is reversed (14). The fluorescence of anthracene in a number of solvents has been examined by Bowen and West (18). 

In an effort to carry the success of 29 forward from homogeneous solution [77] to films, the team at Miami has turned to 31 [78], While 31 forms excellent monolayer films at the air-water interface, decent anthracenic fluorescence signatures are not produced until the films are diluted substantially with stearic acid and deposited onto hydrophobic glass. As may be anticipated, neat films of 31 only show broad excimeric emissions. Light collection problems dog the experiments on the films on water. No sensitivity of the emission towards pH is found, so experiments with saxitoxin are not reported at this stage. We note the closely related PET system 32 which shows good sensing of membrane-bounded protons in micellar media [79],... 

Figure 10.12 Binding constants analysis for quenching of pyrene, fluoranthene, and anthracene fluorescence with Aldrich HS. Reprinted with permission from Perminova, I., Grechishcheva, N. and Petrosyan, V. (1 999). Environmental Science and Technology, 33, 3781-3787. Copyright 1999 American Chemical Society.

In fluid solutions, Faulkner and Bard first found the MFEs on the electrogenerated chemiluminescence of anthracence triplet-triplet annihilation [4], The general features of the MFEs were similar to those observed in crystals the intensity of delayed fluorescence was found to decrease with increasing B from 0 T to 0.8 T and to approach as3miptotically a value which was about 4 % below the zero-field intensity. They also found the MFEs on the anthracene fluorescence in the presence of doublet species such as Wurster s Blue perchlorate [5] the fluorescence intensity was found to be quenched by the doublet species, but the quenched intensity was found to be increased by magnetic fields. Their typical results are shown in Fig. 12-2. Although these MFEs observed in fluid solutions were smaller than those in crystals due to rotational motion of triplet molecules, the MFEs in solutions could also be explained by Eqs. (13-3) and (13-9). The magnetically induced decrease in the... 

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