Resolution of overlapping UV–Vis absorption bands and quantitative analysis

Abstract

Electronic transitions appear in the spectrum as individual bands, described by three basic parameters (position, intensity and width), which can be used for estimation of the fundamental transition characteristics as well as for quantitative analysis. The main problems concerning the mathematical resolution of overlapped individual bands in a complicated spectrum (estimation of the number of overlapping bands, the noise problem, artificial baseline and efficiency of the computing procedure) are discussed and a principal scheme and some solutions are suggested. The use of the resolution of overlapping bands technique for quantitative analysis is given step-by-step in its historical development on real spectral problems. Although the described methods for quantitative analysis are discussed only in terms of UV-Vis spectroscopy they can be easily used in all branches of molecular spectroscopy.

Solid state tautomerism in 2-((phenylimino)methyl)naphthalene-1-ol

“…The absorption spectra of 1 in solution were recorded on a JASCO V-570 UV-Vis-NIR spectrophotometer equipped with a Julabo ED5 thermostat (precision 1 C) at room temperature (20 C) according to the previously described methodology [12,15]. The used solvents were of spectral grade.…”

“…used and requires experimental results to prove theoretical findings. Unfortunately, due to different experimental conditions and assumptions in the models for data processing, optical and NMR spectroscopy cannot guarantee the full reliability of the experimentally obtained tautomeric constants ( [13,15]. The concentration difference between UV-Vis and NMR measurements could be considered as a reason for the difference in the obtained tautomeric constants (under the same other experimental conditions like temperature and solvent) [12].…”

Tautomerism in 1-phenylazo-4-naphthols: Experimental results vs quantum-chemical predictions

“…Only recently advanced chemometric tools for processing of spectra of tautomeric mixtures have been developed and used to study in exact, quantitative, manner the tautomerism in 1 and in related azonaphthols and Schiff bases [6,8]. This has created conditions for exact estimation of the thermodynamic parameters governing the equilibrium (entropy, enthalpy, free energy) in nonpolar solvents, 1 which gives a chance for direct comparison with the quantum-chemical results avoiding the complications of theoretical description of the specific solvent effects [1,9].…”

“…Especially for this study the tautomeric constant in i-octane was estimated according to the methodology already described in the literature [6,8]. A value of K T ¼ 0.096 was obtained, which corresponds to ΔG ¼ 1.38 kcal mol À1 at 298 K.…”

Spectral-Luminescent Properties of meso-Tetraarylporphyrins Revisited: The Role of Aryl Type, Substitution Pattern and Macrocycle Core Protonation

“…Additionally, when available, the validity of the evaluation of the spectral profiles was verified by the determination of the hidden bands maxima with the second derivative method. [52] The fluorescence spectra of the monoprotonated form also demonstrate a bathochromic shift of the band maxima upon going from Mes 4 to Ph 4 . However, if the Q x (0,1) band peak position of the monoprotonated species is compared with the corresponding value for the free base, one can see that the spectra of the monoprotonated form of Mes 4 and Mes 3 Ph show hypsochromic shifts, whereas for the other three derivatives (Mes 2 Ph 2 -trans, Mes 2 Ph 2 -cis and MesPh 3 ) a bathochromic shift is observed.…”