Some transition metal complexes with Schiff bases of aminoguanidine

Abstract

<p>&nbsp;&nbsp; U ovoj doktorskoj disertaciji opisane su sinteze novih kompleksa prelaznih metala sa piridoksiliden-&nbsp; (PLAG), odnosno saliciliden-aminogvanidinom (SALAG). Dobijeni<br />kompleksi su okarakterisani elementalnom analizom, IR spektrima, konduktometrijskim i magnetnim merenjima, a većina i rendgenskom<br />strukturnom analizom. Osim toga, dobijene su i nove forme ovih &Scaron;ifovih baza, i to u vidu monokristala, čime su omogućena ispitivanja njihovih&nbsp; molekulskih i kristalnih struktura, kao i uporedna analiza sa koordinovanim ligandima.<br />&nbsp; &nbsp; Sa PLAG je sintetisano 7 novi&nbsp; kompleksa Cu(II), a pored toga po prvi put su<br />izolovani mono i bis(ligand) kompleksi Fe(III) i Co(III), mono(ligand) kompleksi&nbsp; V(V), kao&nbsp; i jedan kompleks Zn(II) u kojem ovaj potencijalno tridentatni&nbsp;<em> ONN&nbsp;</em> ligand,&nbsp; u<br />monoprotonovanoj formi,&nbsp; ima ulogu kontra-jona. Sa stanovi&scaron;ta geometrije zajedničko za izolovane komplekse Cu(II) i V(V) je da imaju kvadratno-piramidalnu strukturu, sa izuzetkom jednog kvadratno-planarnog kompleksa Cu(II), dok je u kompleksima Fe(III) i Co(III) nađeno očekivano oktaedarsko okruženje centralnog<br />jona. Pored ovih, sintetisano je i pet novih kompleksa sa SALAG, od kojih su dva<br />kompleksa Cu(II) i kompleks V(V) okarakterisani rendgenskom strukturnom<br />analizom, dok je mikrokristalnim bis(ligand) kompleksima Co(III) i Ni(III) na osnovu<br />fizičko-hemijskih karakteristika predložena odgovarajuća struktura.<br />&nbsp;&nbsp; Zajedničko za obe opisane &Scaron;ifove baze je da se koordinuju na&nbsp;<em> ONN&nbsp; </em>tridentatni način, i to preko atoma kiseonika deprotonovane fenolne grupe i atoma azota azometinske i imino grupe AG fragmeta. Posebno je nagla&scaron;eno da su&nbsp; sa<br />PLAG izolovana dva dimerna kompleksa Cu(II) u kojima je po prvi put nađena tetradentatna koordinacija ovog&nbsp; liganda, u koju je dodatno uključen atom kiseonika hidroksimetil-grupe PL-ostatka. Za razliku od SALAG, koji je u izolovanim kompleksima koordinovan isključivo kao monoanjon, nastao deprotonacijom fenolne<br />OH-grupe, za PLAG je osim ove, potvđena koordinacija u neutralnoj, zwitter-jonskoj, ali i dvostruko deprotonovanoj formi. Zwitter-jonska forma liganda nastaje migracijom atoma vodonika sa fenolnog hidroksila na piridinski atom azota PL-ostatka, dok deprotonacijom piridinskog ili hidrazinskog atoma azota, odnosno oba pomenuta atoma nastaju monoanjon i dianjon helatnog liganda, respektivno.<br />&nbsp;&nbsp; Na kraju, urađena su&nbsp; i ispitivanja antimikrobne aktivnosti odabranih jedinjenja<br />prema predstavnicima grampozitivnih i gramnegativnih bakterija, kao i dve kulture<br />kvasca. Tom prilikom nije utvrđena nikakva inhibitorna aktivnost&nbsp;&nbsp; prema primenjenim<br />bakterijskim sojevima, dok su u slučaju kvasaca izvesno mikrobicidno dejstvo pokazali samo kompleksi Cu(II).</p>

<p>This PhD thesis describes the syntheses of some new transition metal complexes with&nbsp; pyridoxilidene-&nbsp; (PLAG) and salicylideneaminoguanidine (SALAG). Obtained&nbsp; complexes are characterized by&nbsp;&nbsp; elemental analysis, IR&nbsp; spectroscopy,&nbsp; conductometric and magnetic measurements. Besides, the structural analysis of majority of the obtained complexes was performed. Some new forms of these Schiff&nbsp; bases are synthesized in form of single crystals, which made their X-ray analysis as well as comparison with coordinated forms possible.</p><p>With PLAG, 7 new Cu(II) complexes were obtained and for the first time mono and bis(ligand) complexes of Fe(III) and Co(III) as well&nbsp; mono(ligand)&nbsp; complexes&nbsp; of V(V) were isolated. Furthermore,&nbsp; the structure of Zn(II) complex in which PLAG in its monocationic form has a role of counter ion is presented. With the exception of one Cu(II) complex, all reported Cu(II) and V(V) complexes have a square-pyramidal geometry, whilst&nbsp; Fe(III)&nbsp; and Co(III)&nbsp; are situated in octahedral surroundings. Also, five new complexes of Cu(II), Co(III), Ni(II) and V(V) with SALAG were synthesized. In both&nbsp; Cu(II) complexes and V(V) complex the expected coordination mode and geometry were confirmed by X-ray analysis, while octahedral structure of bis(ligand) complexes with Co(III) and Ni(II) was proposed based on results of physico-chemical&nbsp; characterization.</p><p>Both PLAG and SALAG coordinate the metal ion in tridentate&nbsp; ONN&nbsp; manner, through the oxygen atom of deprotonated phenolic group and nitrogen atoms&nbsp; of azomethine and imino groups of AG moiety. It is also emphasized that in two dimeric Cu(II) complexes with PLAG tetradentate coordination mode was found, in which the oxygen atom of hydroxymethyl group of PL residue was additionally involved. Unlike SALAG, which is coordinated as monoanion in all of the examined complexes, PLAG can have one of three degrees of deprotonation. Zwitter-ion of PLAG is formed by migration of H-atom from phenolic oxygen to pyridine nitrogen, while the deprotonation of pyridine or/and hydrazine nitrogen, makes it mono-and dianion, respectively.</p><p>Also, microbiological tests on the selected compounds were preformed. Namely, antimicrobial activity of these compounds against some gram-positive and gram-negative bacteria, as well as some yeast cultures was examined and none of the samples showed antimicrobial activity against bacteria, whilst only Cu(II) complexes showed certain inhibitory effect against yeasts.</p>