Naslov
Spectroscopic Evaluation of Cyclic Trishydroxamates for their Chelating Ability

Autori
Kos, Ivan ; Jadrijević-Mladar Takač, Milena ; Biruš, Mladen ; Butula Ivan ; Gabričević, Mario ;

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
European Journal of Pharmaceutical Sciences, Vol. 11/Suppl. 1 (2002) ; Abstracts / Linden, H. - Oxford : Elsevier, 2002

Skup
7th European Congress of Pharmaceutical Sciences(EUFEPS 2002)

Mjesto i datum
Stockholm, Švedska, 20.10.2002. - 23.10.2002

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Chelating ability; Complexation; Hydroxamate ligands; Fe(III)-complexes
(Chelating ability; Complexation; trihydroxy-triazinones; Fe(III)-complexes; Hydroxamate ligands)

Sažetak
In the course of our work on the triazinone chemistry [1] we have studied the chelating ability of 1, 3, 5-trihydroxy-1, 3, 5-triazin-2, 4, 6[1H, 3H, 5H]-trione (L) as cyclic tripodal hydroxamate siderophore. Although there have been extensive studies of iron(III) complexation [2], only limited information is available about complexation of iron(III) with multitopic hydroxamic acids [3]. Tripodal cyclic hydroxamate ligand, L, was prepared according to a previously published procedure [1]. The ligand strucuture was confirmed by means of FTIR, NMR, MS, X-Ray and TGA analysis. Ligand pKa values were determined by potentiometric titration (pKa1=5.23, pKa2=6.32, and pKa3=7.93). The iron(III) chelating properties of L were investigated by UV-VIS and FTIR (CaF2 cell) spectroscopic methods. Iron(III) complexes were prepared by mixing of aqueous solutions of iron perchlorate and L in different molar ratio (1:1, 1:5, 5:1). The formation of iron(III) complexes was observed below pH 2, whereas at higher pH values the precipitation occurred. The formed complexes showed strong absorption in the visible region (lmax 450 nm), while L absorbs in UV region (200 to 300 nm). FTIR spectra revealed that upon the pH increase the nC=O in L were shifted toward smaller wavenumbers (from 1725 to 1704 cm-1), possibly due to deprotonation of OH groups. In FTIR spectra of complexes, nC=O were also pH dependent but shifted toward higher wavenumbers up to 11 cm-1 (molar ratio 1:1 and 1:5) while in 5:1 ratio the shifting were similar to that in free L but of smaller extent (up to 6 cm-1). Our results reveal that the complexation of iron(III) with the cyclic trihidroxamate is pH and the molar ratio dependent. [1] Butula I, Jadrijević-Mladar Takač M. Reactions with 1-Benzotriazolecarboxylic Acid Chloride. VIII. Synthesis of N-Hydroxyisocyanate Derivatives. Croat Chem Acta 2000 ; 73: 569-74. [2] Biruš M, Kujundžić N, Pribanić M., Kinetics of Complexation of Iron(III) in Aqueous Solution, Prog React Kinet 1993 ; 18: 171-271. [3] Hara Y., Akiyama M. An Iron Reservoir Model Based on Ferrichrome: Iron(III)-Binding and Metal(III)-Excange Properties of Tripodal Monotopic and Ditopic Hydroxamate Ligands with an L-Alanyl-L-alanyl-N-hydroxy-b-alanyl Sequence. J Am Chem Soc 2001 ; 123: 7247-56.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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