Pyrene, sulfonation

In a simulated atmosphere, direct epoxidation by ozone led to the formation of benzo[a]pyrene-4,5-oxide. Benzo [a] pyrene reacted with benzoyl peroxide to form the 6-benzoyloxy derivative (quoted, Nikolaou et al, 1984). It was reported that benzo [a] pyrene adsorbed on fly ash and alumina reacted with sulfur dioxide (10%) in air to form benzo[a]pyrene sulfonic acid (Nielsen et al., 1983). Benzo [a] pyrene coated on a quartz surface was subjected to ozone and natural sunlight for 4 and 2 h, respectively. The compounds 1,6-quinone, 3,6-quinone, and the 6,12-quinone of benzo[a]pyrene were formed in both instances (Rajagopalan et al., 1983). 

The lifetime of PN++ is much enhanced on the anionic NaLS and silica particles compared to water. An interesting feature of the silica particles is that PN++ is easily observed, hut unlike micelles or water e-g n is not observed. This is not due to the fact that e g reacts with silica, as e aq produced in the water bulk by photo-ionization of pyrene sulfonic acid (this molecule does not well bind to silica), has a long lifetime,... 

Table I shows the effect of various systems such as micelles, swollen micelles (achieved by adding hexanol to CTAB), microemulsion systems, vesicles formed from a double-chain CTAB surfactant, and reversed micelles with water cores formed with benzyl dimethylcetylammonium bromide in benzene. Hie active chromophore exists either as pyrene, pyrene sulfonic acid or pyrene tetrasulfonlc acid. Essentially the concept here is that the polar derivatives of pyrene will always locate pyrene at the surface of the micelle as these anionic species of pyrene complex with the positively charged surface. Dimethylaniline is used as an electron donor in each case, it can be seen that for pyrene, a continual decrease in the yield of the pyrene anion (ion yield of unity in the micelle) is observed on going from micelle to swollen micelle, to microemulsion, and no yield of ions is observed in a reversed micelle system. With pyrene tetrasulfonic acid the yield of ions over the different systems is fairly constant, even across to the reverse micellar system. However, the lifetime of the ions is extremely short in the reversed micellar system. An explanation for such behavior can be given as follows as we transverse across the...

Hence, the exiplex has a sandwich structure which promotes efficient back e transfer at the water pool, and the ion yield is very small. However, a sandwich reactant pair of this sort is not formed on a micelle surface and back reaction is slower than the escape of the cation from the surface. Hie swollen micelle and microemulsion systems lead to both randomly organised ionic products and sandwich pairs, to varying extents, which are reflected in the observed yield of ions, with polar derivatives of pyrene, e.g. pyrene sulfonic acid, etc., the reactants are kept on the assembly surface where reaction occurs, giving rise to ions from a non-sandwiched type of configuration. In the reverse micellar system, these ions although they are formed, nevertheless have a short lifetime, as they cannot escape to any great distance in the small water pool. Huts, micelles are far superior to microemulsions in various aspects of... 

This method was then applied to study pyrene-sulfonate adsorption and dimerization at the Fl20-1,2-DCE interface [141]. More recently, Nagatani et al. extended their PMF spectroscopy investigation to the study of the adsorption and transfer of free-base, water-soluble porphyrins, namely, cationic meso-tetrakis (N-methylpyridyl) porphyrin (H2TMPyP +) and anionic meso-tetrakis(4-sulfonatophenyl)porphyrin (HTPPS" ) [142]. The PMF response indicated the presence of an adsorption process for all systems, depending on the... 

Nakatani, K., H. Nagatani, D. J. Fermin, and H. H. Giranlt, Transfer and adsorption of 1-pyrene sulfonate at the waterll,2-dichloroethane interface stndied by potential modulated fluorescence spectroscopy, J Electroanal Chem, Vol. 518, (2002) p. 1. 

Dyes, Dye Intermediates, and Naphthalene. Several thousand different synthetic dyes are known, having a total worldwide consumption of 298 million kg/yr (see Dyes AND dye intermediates). Many dyes contain some form of sulfonate as —SO H, —SO Na, or —SO2NH2. Acid dyes, solvent dyes, basic dyes, disperse dyes, fiber-reactive dyes, and vat dyes can have one or more sulfonic acid groups incorporated into their molecular stmcture. The raw materials used for the manufacture of dyes are mainly aromatic hydrocarbons (67—74) and include ben2ene, toluene, naphthalene, anthracene, pyrene, phenol (qv), pyridine, and carba2ole. Anthraquinone sulfonic acid is an important dye intermediate and is prepared by sulfonation of anthraquinone using sulfur trioxide and sulfuric acid. 

This procedure is based on the method of Smith, Opie, Waw-zonek, and Prichard3 for the preparation of 2,3,6-trimethyl-phenol. 3-Hydroxypyrene has been prepared by fusion of pyrene-3-sulfonic acid with sodium hydroxide 4 and by desul-fonation of 3-hydroxypyrene-5,8,10-trisulfonic acid with hot, dilute sulfuric acid.5... 

Chemical/Physical. At room temperature, concentrated sulfuric acid will react with pyrene to form a mixture of disulfonic acids. In addition, an atmosphere containing 10% sulfur dioxide transformed pyrene into many sulfur compounds, including pyrene-1-sulfonic acid and pyrenedisulfonic acid (Nielsen et al., 1983). 

Pyrene Carboxaldehyde Probe Studies. Fluorescence spectra of 1-pyrene carboxaldehyde in nonane solutions of sulfonates A and B and In an octane solution of Aerosol OT are compared to the probe spectra in pure hydrocarbon media in Figure 1. Parts (a) and (b) are of sulfonates A and B systems, respectively part (c) is of aerosol OT system. They were constructed at different gain settings and therefore the intensities shown for the individual system are not directly comparable. The fluorescence intensity of 1-pyrene carboxaldehyde in nonane alone is much weaker than in either the sulfonate A or sulfonate B solution. Aerosol OT containing solubilized H.O does not enhance the fluorescence intensity of 1-pyrene carboxardehyde as much as sulfonates A and B, but the band maximum is shifted as expected for this probe in a water-rich medium. 

We measured the time-dependent anisotropy of 1-pyrene carboxaldehyde in sulfonate A and B systems. The results are shown in Figure 2. Relaxation times determined from the unconvoluted anisotropy decays for sulfonates A and B in heptane solution were found to be 7 ns and 28 ns, respectively. 

In order to test further the applicability of 1-pyrene carboxaldehyde as a fluorescent probe, we applied Keh and Valeur s method (4) to determine average micellar sizes of sulfonate A and B micelles. This method is based on the assumption that the motion of a probe molecule is coupled to that of the micelle, and that the micellar hydrodynamic volumes are the same in two apolar solvents of different viscosities. For our purposes, time averaged anisotropies of these systems were measured in two n-alkanes hexane and nonane. The fluorescence lifetime of 1-pyrene carboxaldehyde with the two sulfonates in both these solvents was found to be approximately 5 ns. The micellar sizes (diameter) calculated for sulfonates A and B were 53 5A and 82 lOA, respectively. Since these micelles possesed solid polar cores, they were probably more tightly bound than typical inverted micelles such as those of aerosol OT. Hence, it was expected that the probe molecules would not perturb the micelles to an extent which would substantially affect the micellar sizes measured. 

Lateral Mobility(Fluidity) of Sulfonate A and B Micelles. The ratio of excimer to monomer fluorescence intensity of pyrene had previously been used to measure the fluidity of biological membranes (8). The ease of excimer formation was correlated with the fluidity of the membrane. The same principle may be applied to the measurement of fluidity in inverted micelles. To this end, we used three pyrene carboxylic acid probes of varying chain length PVA, PNA and... 

Figure 2. Unconvoluted anisotropy decays of 1-pyrene car ox-aldehyde in sulfonate micelles (a) sulfonate A (5 x 10 M)/ heptane (7 ns), (b) Sulfonate B (5 x 10 M /heptane (28 ns). The cmc of sulfonate A is less than 10 °M, while that of sulfonate B is "infinitely" dilute.

For this study, we maintained the pyrene probe concentrations constant, while we varied sulfonate concentration. The measured excimer to monomer ratios as a function of the molar ratio of probe to sulfonate for sulfonates A and B are shown in Figure 3. 

Polarity Variation in Sulfonate Micelles. Other workers have established a correlation between the fluorescence lifetime of pyrene in solution and the polarity of the solvent medium (9). Polar media quench the excited electronic state of pyrene and hence shorten its fluorescence lifetime. We applied this principle to measure the polarity variation within the micelles of sulfonates A and B. 

Pyrene Carboxaldehyde in Calcium Alkarylsulfonates. Our work shows that 1-pyrene carboxaldehyde as a fluorescent probe for the sulfonate systems behaves very much the same as rhodamine B (1 ) and anillnonaphthalene sulfonate (2), whose fluorescence intensities in hydrocarbon media are enhanced in the presence of inverted micelles. However, the intensity Increase observed with AOT was considerably less than that observed with the sulfonates. It is speculated that... 

Figure 5. Plots of the fluorescence lifetime of pyrene as a function of distance from the polar core of the micelles of sulfonates A and B in heptane solutions.

The internal rotational relaxation times of 1-pyrene carboxaldehyde in sulfonate systems may offer some indication of the extent of probe binding to the inverted micelle. In the absence of any background fluorescence interference to the time-dependent anisotropy decay profile, the internal rotational relaxation time should correlate with the strength of binding with the polar material in the polar core. However, spectral interference from the aromatic moieties of sulfonates is substantial, so that the values of internal rotational relaxation time can only be used for qualitative comparison. 

Lateral Mobility in Alkarylsulfonate Micelles. In order to make a valid comparison of fluidity between sulfonates A and B, the micellar sizes should be comparable. This condition is required so that equal population of pyrene moieties between the two sulfonate systems can be assumed. Alternatively, the requirements might be met if they have equal aggregation numbers. If the above-mentioned (See Section A under "Results") assumptions regarding polar core composition are reasonable, the condition for equal probe population between the two sulfonate micelles can still be reasonably approximated. 

Even cyclophanes containing large aromatic units such as pyrene, anthracene, or benzophenanthrene units or partially hydrogenated annulated systems can easily be desulfurized via sulfone pyrolysis, as Staab et al. have shown in a series of works on such compounds [49 53],... 

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