Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Wiadomości Chemiczne

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: kompleksy jonów metali

Sortuj według:

Ogranicz wyniki do:

Antybiotyki peptydowe i ich kompleksy z jonami metali

Stokowa-Sołtys K.

Wiadomości Chemiczne

2018

[Z] 72, 7-8

497--522

Metal ions are essential for numerous antibiotics. They play a crucial role in the mechanism of action and may be involved in specific interactions with cell membrane or target molecules, such as: proteins and nucleic acids. Due to the fact that complexes usually poses a higher positive charge than free ligands, they might interact more tightly with DNA and RNA molecules. However, complexes may also form during antimicrobial agents application, because a lot of them possess functional groups which can bind metal ions present in physiological fluids. Many recent studies support a hypothesis that drugs may alter the serum metal ions concentration. Moreover, it has been shown that numerous complexes with antibiotics can cause DNA degradation, e.g. bleomycin which form stable complexes with redox metal ions and split the nucleic acids chain via the free radicals mechanism. Therefore, it is widely used in cancer therapy.

Kompleksy jonów metali d- i f-elektronowych z N-tlenkiem pirydyny i związkami pochodnymi : badania spektroskopowe

Hnatejko Z.

Wiadomości Chemiczne

2011

[Z] 65, 5-6

461-501

This article reviews results of studies, collected in the literature, related to complexation abilities of pyridine N-oxides, including forms and properties of dand f-metal ion complexes with this group of ligands. In this paper the synthetic pathways of the ligands, based on an oxidation of the corresponding heterocyclic compounds are presented (Scheme 3) [2, 4, 5]. Substituted pyridine N-oxides form an interesting group of compounds, which have found numerous applications [296-299, 314-318]. They have been used in catalysis, crystal engineering, synthesis of coordination polymers, as well as drugs and components in pharmaceutical chemistry [300-309]. Some of them are useful in destroying of microorganisms and the HIV virus [277, 278, 303-307]. Moreover, they are important compounds in the thermal and photochemical oxidation processes [296-299]. The complexes of metal ions with the N-oxide ligands can be formed by binding an oxygen atom of the N›O group, and/or by binding the substituents present in the aromatic ring, e.g. oxygen atoms of carboxylic groups. The complexes can be obtained in monomeric [64, 159], dimeric [58] or polymeric forms [60, 153, 175]. The formation of polymeric forms is more effective when the distance between the positions of COOH and N›O groups in the aromatic ring increases [168]. Complexes of Ln3+ ions and particularly of Eu3+ with pyridine N-oxides are good luminescent materials, better than their heterocyclic counterparts [180, 211]. The emission intensity of europium ions in these systems depends on the efficiency of the LMCT (ligand-metal charge transfer) and LMET (ligand-metal energy transfer) transitions, as well as on electron-donor properties of the substituents present in the pyridine N-oxide ring [37, 132, 155]. A special role in the complexation of Ln3+ ions plays cryptands, which can encapsulate the metal ion. This process protects the metal ion from a penetration of its first coordination sphere by solvent molecules or counterions [245, 246]. The complexes of europium(III) with macromonocyclic, macrobicyclic and acyclic ligands, equipped with photoactive units such as pyridine N-oxide, 2,2'-bipyridine-N,N'-dioxide or 3,3'-biisoquinoline-2,2'-dioxide in solutions, solid states, and incorporated in a silicate matrices by sol-gel method, gained a lot of attention [247-274].