Renata Jastrzab

Interactions in binary and ternary systems including Cu(II), uridine, uridine 5′-monophosphate or diamine

Abstract Results of equilibrium and spectral studies have shown that, in the systems of uridine (Urd) or uridine 5′-monophosphate (UMP) with the diamines (PA) ethylenediamine, 1,3-diaminopropane or putrescine, molecular complexes of the type (Urd)Hx(PA) and (UMP)Hx(PA) are formed. Overall stability constants of the adducts and equilibrium constants of their formation have been determined. The tendency towards complex formation increases with growing length of the PA. The pH range of adduct formation is found to coincide with that in which the PA is protonated, whereas Urd or its monophosphate is deprotonated. The NH3+ groups from PA and N(3) atoms and phosphate groups from the nucleosides have been identified as the centres of non-covalent interactions. Overall stability constants of the Cu(II) complexes with Urd and UMP have been determined. It was found that, in the Cu(Urd)+ and Cu(Urd)(OH)x complexes, the reaction of metallation mainly involves N(3) atoms from the pyrimidine bases. Results of the spectral and equilibrium studies of the Cu/UMP system indicate coordination involving the N(3) atom and the phosphate groups from UMP, whereas in the complexes Cu(UMP)(OH)x, appearing at high pH, the involvement of the N(3) atom has been excluded and the main sites of metallation are oxygen atoms from carbonyl groups, besides those from hydroxyl groups. The mode of coordination of Cu(II) complexes with Urd or UMP, including diamines, was also determined.

Intermolecular and coordination reactions in the systems of copper(II) with adenosine 5′-monophosphate or cytidine 5′-monophosphate and triamines

Formation of molecular complexes as a result of non-covalent interactions between adenosine 5-monophosphate (AMP) or cytidine 5-monophosphate (CMP) and polyamines, 1,5-diamino-3-azapentane (dien) or 1,6-diamino-3-azahexane (2,3-tri), has been studied in metal-free systems. Based on the acid–base equilibrium changes, the composition and stability constants of the molecular complexes formed have been determined. Spectral analysis has revealed that the interaction centers in these adducts are protonated amine groups from the polyamine, phosphate groups and donor nitrogen atoms from the nucleotide. In the ternary systems of Cu(II) with AMP or CMP and polyamines, dien or 2,3-tri, the composition and stability constants of the heteroligand complexes formed have been determined. The presence of the following complexes has been detected: Cu(CMP)(dien), Cu(AMP)(dien), Cu(CMP)(2,3-tri), Cu(CMP)(2,3-tri)(OH). Results of the equilibrium and spectral studies (Vis, IR, EPR, 13 C, 31 P NMR) have shown that in the mixed complexes, all nitrogen atoms from the polyamine and oxygen atoms from the phosphate group of the nucleotide take part in the coordination. The donor nitrogen atoms N(1) and N(7) from AMP and N(3) from CMP are in the outer coordination sphere.

Studies of new phosphothreonine complexes formed in binary and ternary systems including biogenic amines and copper(II)

Binary and ternary systems of copper(II) with O-phospho-L-threonine (Thr-P) and biogenic amines (putrescine or spermidine or spermine) have been investigated. The studies were performed in aqueous solution. Overall stability constants of the complexes were determined by pH-metric study and the coordination sites were identified by 31P NMR, visible and electron paramagnetic resonance spectroscopies. Results of the equilibrium and spectral studies have shown that in the phosphothreonine binary system Cu(HThr-P), Cu(Thr-P) and Cu(Thr-P)(OH) are formed. In the binary system at low pH, only the phosphate group is involved in coordination but at higher pH, the efficiency of −PO4 2− is low and the amine and carboxylate are the main sites of coordination. Formation of complexes was established in ternary systems with all bioamines studied. In these systems the reaction centers of phosphothreonine are the same as in the binary systems: phosphate, carboxylate and amine. Additionally, amine groups from the polyamines (PAs) are involved in the complex formation. Besides the heteroligand complexes with intermolecular interactions, also molecular complexes with the protonated bioamine in the outer coordination sphere appeared. In these molecular species, PA was involved in non-covalent interactions with the anchoring phospho-threonine complex.

Coordination mode in the binary systems of copper(II)/O-phospho-L-serine

Results of equilibrium and spectral studies have shown that in the O-phospho-L-serine (Ser-P) with copper(II) system the complexes MHL, ML, ML2 and ML(OH) x are formed; overall stability constants of the Cu(II) species have been determined. Coordination mode in the complexes was concluded on the basis of spectral investigation (NMR, 31P NMR, 1H–15N NMR, IR, EPR and Vis). In the Cu/phosphoserine system at low pH, coordination mainly involves the phosphate group. At higher pH, the efficiency of– is low and coordination is by the amine and carboxyl groups. Differences in the coordination mode in the phosphoserine complex at low pH, compared to those of endogenic serine, in their reactions with copper(II) ions have been observed.

Potentiometric and spectral studies of complex formation in the Cu(II), 3',5'-cyclic adenosine monophosphate, and tetramine systems

Reactions in the systems composed of copper(II), 3′,5′-cyclic adenosine monophosphate (cAMP), and tetramines (PA) were studied. On the basis of potentiometric and spectroscopic data in metal-free systems, formation of molecular complexes (cAMP)Hx(PA), x = 2–4, was found. Stabilities of the complexes were determined and their centers of interactions were identified. In Cu(II)/cAMP, formation of Cu(cAMP) and Cu(cAMP)(OH) was observed, with the phosphate as the main site of metallation, while in ternary systems, formation of Cu(cAMP)H4(Spm) and Cu(cAMP)(3,3,3-tet) was established. Characteristic differences in the coordination character of tetramines were found. In the Cu(II)/cAMP/Spm system, oxygens from the nucleotide phosphate are involved in metallation and protonated amines are engaged in noncovalent interaction with endocyclic nitrogens of nucleoside. In the Cu(II)/cAMP/3,3,3-tet system, a MLL′ complex is formed in which the inner coordination sphere includes polyamine nitrogens as well as the nucleotide phosphate.

Complexing ability of (−)-cytisine — Synthesis, spectroscopy and crystal structures of the new copper and zinc complexes

For the first time the NMR spectra of quinolizidine alkaloid with Cu(II) are studied. Structures of new complexes of (-)-cytisine with Cu(+2) and Zn(+2) cations are visualized, discussed in detail and characterized by spectroscopic methods: ESI-MS, NMR, UV-vis, EPR and crystallographic methods. In solution metal coordinates through the protonated nitrogen atoms of secondary amino groups (in piperidine ring) of cytisine molecule. While in solid state the most stable structures of the complexes are those in which the coordination of Cu(II) and Zn(II) salts is realized solely through the lactam carbonyl oxygen atom.

The influence of copper(II) ions on noncovalent interactions in the systems including phosphoserine and biogenic amines

Ternary systems of copper(II) complexes with phosphoserine and biogenic amines (putrescine or spermidine or spermine) have been investigated. The studies were performed in aqueous solution using the potentiometric method with computer analysis of the data, 13C and 31P nuclear magnetic resonance, visible and electron paramagnetic resonance spectroscopies. The composition and overall stability constants of the complexes were determined by the pH-metric study and the coordination sites were identified by spectroscopic methods. The reaction centres are phosphate, carboxyl and amine groups from phosphorylated serine as well as amine groups from polyamine. These centres are also the potential sites of the noncovalent interactions (in the systems without metal). In the systems studied only protonated complexes formed. Besides the heteroligand complexes and heteroligand complexes with intermolecular interactions, molecular complexes with the protonated bioamine in the outer coordination sphere appeared. In these molecular species polyamine was involved in noncovalent interactions with the anchoring phosphoserine complex.

Complexation copper(II) or magnesium ions with d-glucuronic acid – potentiometric, spectral and theoretical studies

Abstract Results of potentiometric and spectral studies have shown that in d-glucuronic acid (GluA) with Cu2+ or Mg2+ systems, the complexes ML and ML(OH)x are formed. Overall stability constants (log β) and equilibrium constants (log Ke) were calculated for all complex forms. The mode of coordination for each form was concluded on the basis of spectral values, Vis, EPR, and chemical shifts in the 13C NMR. According to spectral analysis, Cu(GluA) exists in two possible forms, which confirm the occurrence of the coordination dichotomy in the system. The main center of interactions in the hydroxyl complexes Cu(GluA)(OH)x and MgGluA are oxygens from the carboxyl group. Differences in the coordination mode in the copper(II) and magnesium systems at low pH were observed.

Preparation of silver material used for detection of biocomplexes by surface-enhanced Raman scattering

Silver dendrites were obtained on Cu plate by a classic galvanic displacement process. The process of preparing Ag particles was performed at different immersion times in AgNO3 solution, and the best process parameters were selected according to the enhancement effect of the Raman spectra of Rhodamine 6G. Ag-Cu substrates were chosen for a Surface-enhanced Raman scattering (SERS) study of biocomplexes because their preparation is cost effective and simple, and the relative homogeneous signal enhancement on the prepared silver SERS-active substrate was obtained. The rapid process of surface preparation was applied to identify the mode of coordination. Biocomplexes of Co and Ni ions with adenosine triphosphate form in neutral pH were immersed on the Ag dendrites, and SERS spectra of these compounds were collected. This research work was carried out in order to determine different types of coordination in the same pH conditions and relatively low concentration using SERS which is an emerging and promising te...

Heteronuclear complexes of phosphocreatine with copper(II) and magnesium(II) ions

It has been found that in the binary systems Mg(II)/phosphocreatine and Cu(II)/phosphocreatine at low pH, metal ions mainly coordinate via the phosphate group. At higher pH for copper(II) system, the efficiency of –PO32− group is low and coordination takes place via amine and carboxyl groups (Mg2+ is still coordinated to phosphate group). Differences in the coordination mode for copper and magnesium ions in binary systems at high pH suggested that it would be interesting to determine the mode of coordination in heteronuclear complexes and the coordination competitiveness of metal ions towards phosphate group at low and at physiological pH. The formation of heteronuclear complexes of phosphocreatine with Mg2+ and Cu2+ ions was investigated. The overall stability constants of these species were determined by the potentiometric studies and the coordination mode was concluded on the basis of several spectral investigations (EPR, Visible Spectroscopy, 2D 1H-15N NMR, 31P NMR and FT-IR).