From owner-chemistry@ccl.net Mon Feb 28 13:07:00 2011
From: "Guilherme Cordeiro guilhermecord]~[gmail.com" <owner-chemistry . server.ccl.net>
To: CCL
Subject: CCL:G: UV-Vis bands obtained by ZIndo method
Message-Id: <-44029-110228130555-3587-0gM3Dsa5f7bY7s/Q1yRB7A . server.ccl.net>
X-Original-From: "Guilherme  Cordeiro" <guilhermecord],[gmail.com>
Date: Mon, 28 Feb 2011 13:05:54 -0500


Sent to CCL by: "Guilherme  Cordeiro" [guilhermecord/a\gmail.com]
Dear Members,

I obtained the theoretical absorption bands of free quercetin solvated in water by means of the semi-empirical ZIndo method in Gaussian 98W. 

Quercetin, like most flavonols, exhibit two major absorption bands in the UV/vis region. Band I, in the 300-500nm range, and band II for wavelength under 280nm.

In fact, the calculation showed one absorption peak for Band I at 331.54nm and one peak for Band II at 277.34nm. But, according to A. Torreggiani et al, Band I should appear as two absorption peaks at 320 and 375nnm while Band II as one absorption at 260nm.

What should be the reasons for obtaining only one peak in the 300-500nm region? Is there a scaling factor that I can use in order to correct the theoretical valeus?

Citation: Torreggiania, A., Tambaa, M., Trincherob, A., & Bonora, S. (2005). Copper(II)Quercetin complexes in aqueous solutions: spectroscopic and kinetic properties. Journal of Molecular Structure , pp. 759-766.     

Thanks in advance.