SOLVENT AND pH EFFECTS ON UV ABSORPTION SPECTRUM OF 1,3-bis[(3-(2-pyridyl) pyrazol-1 ylmethyl)] ....

The electronic absorption spectra of 1,3-bis[(3-(2-pyridyl) pyrazol-1 ylmethyl)] benzene (1,3-PPB) were studied using single and binary solvents. Because of the pyridyl pyrazole and benzene systems, 1,3-PPB displays two absorbance maxima (250 and 280 nm). The UV absorption frequencies of the electronic transitions were associated using a total solvatochromic equation by Kamlet and Taft in order to explain the acquired results. In pure solvents, the multiparametric analysis shows that the solvent's hydrogen bond donor ability (for band I) and non-specific dipolar interactions (for band II) play key roles in absorption maxima. In the i-PrOH-EtOH solvent mixture, preferential ethanol solvation (for two bands) was identified. The dissociation constant (pKb) was estimated using two spectrophotometric graphical approaches, with an average value of 10.120.41.

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