The fluorescence of some biphenyl derivatives

Abstract

1. The variation with pH of the excitation and fluorescence wavelengths and fluorescence intensity of several hydroxy- and amino-biphenyls has been investigated with a view to using the data for the determination of hydroxybiphenyls in biological material. 2. 2- and 3-Hydroxy-, 2,2'-dihydroxy-, and 2-, 3- and 4-amino-biphenyl exhibited excited-state ionization. 4-Hydroxy- and 4,4'-dihydroxybiphenyl did not, and showed normal fluorescence changes with pH. 3. Biphenyl and 2- and 4-methoxybiphenyl showed no changes in fluorescence in the range pH0-14. 4. 4,4'-Dihydroxybiphenyl showed fluorescent peaks corresponding to the un-ionized form, the monoanion and dianion at the appropriate pH values, but 2,2'-dihydroxybiphenyl showed fluorescent peaks corresponding to the un-ionized form and the monoanion only, suggesting that it did not form a dianion. 5. 3- and 4-Nitrobiphenyl were non-fluorescent. 6. These results are discussed.

A new method using laser induced fluorescence quenching for studying metal complexes in the solid state applied to CrIII, CuII and PbII in sandy soils

“…4 and averaged in Table 2. Deprotonation of functional groups like phenolic, carboxylic and amino groups is known to affect fluorescence quenching in solution (Bridges et al, 1965) and this is the reason why the reference samples (no metal added) were analyzed at the same pH than the samples. The fit obtained according to the model described by Ryan and Weber (1982) for dissolved samples was good, but with higher errors for lower values in metal ions added, especially for lead.…”

Principles of Fluorescence

“…12). The polarization is deflned as (14) that is, the difference of the two observed intensities over their sum. The fluorescent molecules can be considered to have definite axes whose directions may be compared to the directions of the electrical vectorst associated with absorption (excitation).…”

Complex formation equilibria of Cu2+ and Zn2+ with Irbesartan and Losartan

“…The presence of the biphenyl and the imidazole fluorescent groups (fluorophores) allowed to collect the fluorescence spectra of both the ligands from pH 1 to 7 [49], [50]. In the pH range 1 -2 the fluorescence peak shifts towards higher energy both in 30 In Figure 3, the fluorescence intensities at fixed wavelength are superimposed to the speciation plots obtained from the potentiometric results (Fig.…”