Search

Two azo dye ligands, bearing different substituents (chlorine atom or methoxy group) in the para-position of the phenyl ring, were employed for the synthesis of two Cu(II) chelates. Full structural affirmation of complexes was assessed. X-ray diffraction measurements revealed that the coordination geometry for Cu atoms in both complexes is square-pyramidal with a ligand:metal ratio of 2:1 where dyes behave as monobasic bidentate ligands. Thermogravimetric analyses of the complexes and their starting dyes were performed to study their thermal stabilities and decomposition behavior confirming the thermal stability of both dyes and complexes. Antioxidative activity of the complexes has been assigned and compared with their parent ligands revealing that the presence of the electron–donor, methoxy group, in the phenyl ring, in both dye and complex, is responsible for the activity (IC50 values of 1.54 for the dye and 1.30 mM for the complex). It should be stated that the complexation of the methoxy-substituted dye leads to enhanced antioxidative activity concurrent to a standard antioxidant molecule of ascorbic acid, making this molecule a promising antioxidant agent. Docking study with vascular endothelial growth factor receptor 2 and Aurora kinase A proteins indicate that complexes exhibit higher binding affinities to proteins than the starting ligand dyes. The most promising structure exhibiting the best docking potential toward both proteins is the complex-bearing methoxy group. The presented results represent a promising start for further investigations of these compounds as potential therapeutic candidates for the treatment of various types of cancer.

Two azo dye ligands, bearing different substituents (chlorine atom or methoxy group) in the para-position of the phenyl ring, were employed for the synthesis of two Cu(II) chelates. Full structural affirmation of complexes was assessed. X-ray diffraction measurements revealed that the coordination geometry for Cu atoms in both complexes is square-pyramidal with a ligand:metal ratio of 2:1 where dyes behave as monobasic bidentate ligands. Thermogravimetric analyses of the complexes and their starting dyes were performed to study their thermal stabilities and decomposition behavior confirming the thermal stability of both dyes and complexes. Antioxidative activity of the complexes has been assigned and compared with their parent ligands revealing that the presence of the electron–donor, methoxy group, in the phenyl ring, in both dye and complex, is responsible for the activity (IC50 values of 1.54 for the dye and 1.30 mM for the complex). It should be stated that the complexation of the methoxy-substituted dye leads to enhanced antioxidative activity concurrent to a standard antioxidant molecule of ascorbic acid, making this molecule a promising antioxidant agent. Docking study with vascular endothelial growth factor receptor 2 and Aurora kinase A proteins indicate that complexes exhibit higher binding affinities to proteins than the starting ligand dyes. The most promising structure exhibiting the best docking potential toward both proteins is the complex-bearing methoxy group. The presented results represent a promising start for further investigations of these compounds as potential therapeutic candidates for the treatment of various types of cancer.

The aim of this study was to investigate thermal behavior of the new complex with formula [Cu(ala)cyc](ClO4)2∙2.5H2O. The complex was isolated and previously characterized by: elemental analysis (C, H, N), molar conductivity, UV/Vis and FTIR spectroscopy and magnetic measurements at room temperature. The sixcoordinate octahedral geometry around Cu(II) complexes was proposed. The experimental data suggested that the tetradentate ligand cyclam was coordinated to metals through four N donors and the amino carboxylate ligand coordinated via carboxylate ion. Investigate of thermal stability can be crucial in confirming the structure as well as in assessing the applicability of new compounds. The thermal properties of these complex have been investigated by thermogravimetric (TG) and differential thermal analysis (DTA). Therefore, TG-DTA analysis indicates that investigated complex decomposes exothermally in a single step in the range of 310 - 400 °C.

Copper(II) and zinc(II) complexes with clinically used antifungal drug fluconazole (fcz), {[CuCl2(fcz)(2)](.)5H(2)O}(n), 1, and {[ZnCl2(fcz)(2)]Greek ano teleia2C(2)H(5)OH}(n), 2, were prepared and characterized by spectroscopic and crystallographic methods. The polymeric structure of the complexes comprises four fluconazole molecules monodentately coordinated via the triazole nitrogen and two chlorido ligands. With respect to fluconazole, complex 2 showed significantly higher antifungal activity against Candida krusei and Candida parapsilosis. All tested compounds reduced the total amount of ergosterol at subinhibitory concentrations, indicating that the mode of activity of fluconazole was retained within the complexes, which was corroborated via molecular docking with cytochrome P450 sterol 14 alpha-demethylase (CYP51) as a target. Electrostatic, steric and internal energy interactions between the complexes and enzyme showed that 2 has higher binding potency to this target. Both complexes showed strong inhibition of C. albicans filamentation and biofilm formation at subinhibitory concentrations, with 2 being able to reduce the adherence of C. albicans to A549 cells in vitro. Complex 2 was able to reduce pyocyanin production in Pseudomonas aeruginosa between 10% and 25% and to inhibit its biofilm formation by 20% in comparison to the untreated control. These results suggest that complex 2 may be further examined in the mixed Candida-P. aeruginosa infections.

The interaction of water soluble copper(II) complex, [Cu(dipica)(CH3COO)]ClO4 (1), where dipica is di-(2-picolyl)amine, as in vitro cytotoxic agent, with bovine serum albumin (BSA) has been studied by fluorescence, UV-Vis absorption and circular dichroism (CD) spectroscopic techniques at pH 7.4. The quenching constants and binding parameters such as binding constants and number of binding sites were determined by fluorescence quenching method. The obtained results proved that the fluorescence quenching of BSA by 1 was a result of the formation of a non-fluorescent BSA-1 system with the binding constants of 1.81 x 10-5 M-1 and 2.10 x 10-5 M-1 at 300 K and 310 K respectively. The calculated thermodynamic parameters (G°, H° and S°) confirmed that the binding reaction is mainly entropy-driven and hydrophobic forces played major role in the reaction. The distance, r, between the donor (BSA) and acceptor (1) was obtained according to the Forster theory of nonradiative energy transfer. On the other hand, structural analysis indicates that binding of 1 resulting in a higher change in the local polarity around tryptophan rather than tyrosine residues of BSA as revealed by synchronous fluorescence spectra and a decrease in α-helix as revealed by the far-UV CD spectra.

The interaction of water soluble copper(II) complex, [Cu(dipica)(CH3COO)]ClO4 (1), where dipica is di-(2-picolyl)amine, as in vitro cytotoxic agent, with bovine serum albumin (BSA) has been studied by fluorescence, UV-Vis absorption and circular dichroism (CD) spectroscopic techniques at pH 7.4. The quenching constants and binding parameters such as binding constants and number of binding sites were determined by fluorescence quenching method. The obtained results proved that the fluorescence quenching of BSA by 1 was a result of the formation of a non-fluorescent BSA-1 system with the binding constants of 1.81 x 10-5 M-1 and 2.10 x 10-5 M-1 at 300 K and 310 K respectively. The calculated thermodynamic parameters (G°, H° and S°) confirmed that the binding reaction is mainly entropy-driven and hydrophobic forces played major role in the reaction. The distance, r, between the donor (BSA) and acceptor (1) was obtained according to the Forster theory of nonradiative energy transfer. On the other hand, structural analysis indicates that binding of 1 resulting in a higher change in the local polarity around tryptophan rather than tyrosine residues of BSA as revealed by synchronous fluorescence spectra and a decrease in α-helix as revealed by the far-UV CD spectra.

The novel polymeric complexes catena-poly[[diaquamanganese(II)]-mu-2,2'-bipyrimidine-kappa N-4(1),N-1':N-3,N-3'-[diaquamanganese(II)]-bis(mu-terephthalato-kappa O-2(1):O-4)], [Mn-2(C8H4O4)(2)(C8H6N4)(H2O)(4)](n), (I), and catena-poly[[[aquacopper(II)]-mu-aqua-mu-hydroxido-mu-terephthalato-kappa O-2(1):O-1'-copper(II)-mu-aqua-mu-hydroxido-mu-terephthalato-kappa O-2(1):O-1'-[aquacopper(II)]-mu-2,2'-bipyrimidine-kappa N-4(1),N-1':N-3,N-3'] tetrahydrate], {[Cu-3(C8H4O4)(2)- (OH)(2)(C8H6N4)(H2O)(4)]center dot 4H(2)O}(n), (II), containing bridging 2,2'-bipyrimidine (bpym) ligands coordinated as bis-chelates, have been prepared via a ligand-exchange reaction. In both cases, quite unusual coordination modes of the terephthalate (tpht(2-)) anions were found. In (I), two tpht(2-) anions acting as bis-monodentate ligands bridge the Mn-II centres in a parallel fashion. In (II), the tpht(2-) anions act as endo-bridges and connect two Cu-II centres in combination with additional aqua and hydroxide bridges. In this way, the binuclear [Mn-2(tpht)(2)(bpym)(H2O)(4)] entity in (I) and the trinuclear [Cu-3(tpht)(2)(OH)(2)(bpym)(H2O)(4)]center dot 4H(2)O coordination entity in (II) build up one-dimensional polymeric chains along the b axis. In (I), the Mn-II cation lies on a twofold axis, whereas the four central C atoms of the bpym ligand are located on a mirror plane. In (II), the central Cu-II cation is also on a special position (site symmetry 1). In the crystal structures, the packing of the chains is further strengthened by a system of hydrogen bonds [in both (I) and (II)] and weak face-to-face pi-pi interactions [in (I)], forming three-dimensional metal-organic frameworks. The Mn-II cation in (I) has a trigonally deformed octahedral geometry, whereas the Cu-II cations in (II) are in distorted octahedral environments. The Cu-II polyhedra are inclined relative to each other and share common edges.

The novel polymeric complexes catena-poly[[diaquamanganese(II)]-mu-2,2'-bipyrimidine-kappa N-4(1),N-1':N-3,N-3'-[diaquamanganese(II)]-bis(mu-terephthalato-kappa O-2(1):O-4)], [Mn-2(C8H4O4)(2)(C8H6N4)(H2O)(4)](n), (I), and catena-poly[[[aquacopper(II)]-mu-aqua-mu-hydroxido-mu-terephthalato-kappa O-2(1):O-1'-copper(II)-mu-aqua-mu-hydroxido-mu-terephthalato-kappa O-2(1):O-1'-[aquacopper(II)]-mu-2,2'-bipyrimidine-kappa N-4(1),N-1':N-3,N-3'] tetrahydrate], {[Cu-3(C8H4O4)(2)- (OH)(2)(C8H6N4)(H2O)(4)]center dot 4H(2)O}(n), (II), containing bridging 2,2'-bipyrimidine (bpym) ligands coordinated as bis-chelates, have been prepared via a ligand-exchange reaction. In both cases, quite unusual coordination modes of the terephthalate (tpht(2-)) anions were found. In (I), two tpht(2-) anions acting as bis-monodentate ligands bridge the Mn-II centres in a parallel fashion. In (II), the tpht(2-) anions act as endo-bridges and connect two Cu-II centres in combination with additional aqua and hydroxide bridges. In this way, the binuclear [Mn-2(tpht)(2)(bpym)(H2O)(4)] entity in (I) and the trinuclear [Cu-3(tpht)(2)(OH)(2)(bpym)(H2O)(4)]center dot 4H(2)O coordination entity in (II) build up one-dimensional polymeric chains along the b axis. In (I), the Mn-II cation lies on a twofold axis, whereas the four central C atoms of the bpym ligand are located on a mirror plane. In (II), the central Cu-II cation is also on a special position (site symmetry 1). In the crystal structures, the packing of the chains is further strengthened by a system of hydrogen bonds [in both (I) and (II)] and weak face-to-face pi-pi interactions [in (I)], forming three-dimensional metal-organic frameworks. The Mn-II cation in (I) has a trigonally deformed octahedral geometry, whereas the Cu-II cations in (II) are in distorted octahedral environments. The Cu-II polyhedra are inclined relative to each other and share common edges.

The novel polymeric complexes catena-poly[[diaquamanganese(II)]-mu-2,2'-bipyrimidine-kappa N-4(1),N-1':N-3,N-3'-[diaquamanganese(II)]-bis(mu-terephthalato-kappa O-2(1):O-4)], [Mn-2(C8H4O4)(2)(C8H6N4)(H2O)(4)](n), (I), and catena-poly[[[aquacopper(II)]-mu-aqua-mu-hydroxido-mu-terephthalato-kappa O-2(1):O-1'-copper(II)-mu-aqua-mu-hydroxido-mu-terephthalato-kappa O-2(1):O-1'-[aquacopper(II)]-mu-2,2'-bipyrimidine-kappa N-4(1),N-1':N-3,N-3'] tetrahydrate], {[Cu-3(C8H4O4)(2)- (OH)(2)(C8H6N4)(H2O)(4)]center dot 4H(2)O}(n), (II), containing bridging 2,2'-bipyrimidine (bpym) ligands coordinated as bis-chelates, have been prepared via a ligand-exchange reaction. In both cases, quite unusual coordination modes of the terephthalate (tpht(2-)) anions were found. In (I), two tpht(2-) anions acting as bis-monodentate ligands bridge the Mn-II centres in a parallel fashion. In (II), the tpht(2-) anions act as endo-bridges and connect two Cu-II centres in combination with additional aqua and hydroxide bridges. In this way, the binuclear [Mn-2(tpht)(2)(bpym)(H2O)(4)] entity in (I) and the trinuclear [Cu-3(tpht)(2)(OH)(2)(bpym)(H2O)(4)]center dot 4H(2)O coordination entity in (II) build up one-dimensional polymeric chains along the b axis. In (I), the Mn-II cation lies on a twofold axis, whereas the four central C atoms of the bpym ligand are located on a mirror plane. In (II), the central Cu-II cation is also on a special position (site symmetry 1). In the crystal structures, the packing of the chains is further strengthened by a system of hydrogen bonds [in both (I) and (II)] and weak face-to-face pi-pi interactions [in (I)], forming three-dimensional metal-organic frameworks. The Mn-II cation in (I) has a trigonally deformed octahedral geometry, whereas the Cu-II cations in (II) are in distorted octahedral environments. The Cu-II polyhedra are inclined relative to each other and share common edges.

Two asymmetric tridentate copper(II) complexes, [Cu(dppt)Cl-2].0.25H(2)O (1) (dppt = 3-(1,10-phenanthrolin-2-yl)-5,6-diphenylas-triazine) and [Cu(pta)Cl-2] (2) (pta=3-(1,10-phenanthrolin-2-yl)-as-triazino[5,6-f]acenaphthylene), have been prepared and characterized by elemental analysis, IR and Fast atomic bombardment mass spectra. Complex 1 has also been structurally characterized. The complexes exist as distorted square pyramid with five co-ordination sites occupied by the tridentate ligand and the two chlorine anions. DNA interaction studies suggest that the ligand planarity of the complex has a significant effect on DNA binding affinity increasing in the order [Cu(dppt)Cl-2] < [Cu(pta)Cl-2]. In the presence of ascorbate or glutathione, the two complexes are found to cause significant cleavage of double-strand pBR 322 DNA and [Cu(pta)Cl-2] exhibited the higher cleaving efficiency.

Two asymmetric tridentate copper(II) complexes, [Cu(dppt)Cl-2].0.25H(2)O (1) (dppt = 3-(1,10-phenanthrolin-2-yl)-5,6-diphenylas-triazine) and [Cu(pta)Cl-2] (2) (pta=3-(1,10-phenanthrolin-2-yl)-as-triazino[5,6-f]acenaphthylene), have been prepared and characterized by elemental analysis, IR and Fast atomic bombardment mass spectra. Complex 1 has also been structurally characterized. The complexes exist as distorted square pyramid with five co-ordination sites occupied by the tridentate ligand and the two chlorine anions. DNA interaction studies suggest that the ligand planarity of the complex has a significant effect on DNA binding affinity increasing in the order [Cu(dppt)Cl-2] < [Cu(pta)Cl-2]. In the presence of ascorbate or glutathione, the two complexes are found to cause significant cleavage of double-strand pBR 322 DNA and [Cu(pta)Cl-2] exhibited the higher cleaving efficiency.

Three novel manganese(II) coordination polymers, [Mn (maleate)(phen)](n) (1; phen = 1,10-phenanthroline), [Mn-(maleate)(phen)](n).nH(2)O (2), and [Mn(maleate)(bpy)](n) (3; bpy = 2,2'-bipyridine), have been synthesized by treatment of Mn2+ with maleic acid with participation of chelate diimine ligands, and have been identified by single-crystal, X-ray diffraction to have either one-dimensional (1D) zigzag chain structures (1 and 2) or a two-dimensional (2D) sinuous layer structure (3). Each maleate dianion coordinates to three Mn centers, in different bridging modes (syn-anti in 1 and 2, syn-syn and anti-anti in 3). These compounds represent an interesting example of structural topology variation from 1D to 2D mediated by chemically similar auxiliary chelate ligands. Variable-temperature magnetic susceptibility measurements show weak anti-ferromagnetic exchange interactions between the adjacent Mn-II ions, with J = -0.06 cm(-1) (2) and J = -1.3 cm(-1), zJ' = -0.27 cm(-1) (3). The differences in the magnitudes of these coupling interactions agree well with the nature of the carb oxylate-bridging coordination of maleate., QC 20100525

© 2018, Pleiades Publishing, Ltd. A new water-soluble multidentate ligand based on a second-generation hyperbranched polyester containing 3-(morpholin-4-yl)propionate fragments in the terminal position has been synthesized, and its complex with copper(II) has been obtained. The degree of polyester functionalization with aminopropylmorpholine is 56%.