Homo- and heteropolynuclear Ni2+ and Cu2+ complexes of polytopic ligands, consisting of a tren unit substituted with three 12-membered tetraazamacrocycles
Abstract:Two new polytopic ligands L1 and L2 have been synthesized. They consist of a central tren unit to which three 1,4,7,10-tetraazacyclododecane rings are attached via an ethylene and a trimethylene bridge, respectively. The complexation properties of L1 and L2 towards Cu(2+) and Ni(2+) were studied by potentiometric pH titration, UV-Vis, EPR spectroscopy and kinetic techniques. As a comparison, the Cu(2+) and Ni(2+) complexes with L3 (1-(N-methyl-2-aminoethyl-1,4,7,10-tetraazacyclododecane)) were also investigate… Show more
“…The hypochromic effect of 1 and 3 contributed to the intercalation of 1 and 3 into the DNA base pairs and can be explained by decreasing the distance between DNA bases and intercalated 1 or 3 . Overall, the observed binding constant of the complexes against DNA and 5FU where binding constant were reported to be 5.73 × 10 4 M −1 and 9.7 × 10 4 M −1 , respectively 59 , 60 . Figure 5 UV absorption spectra of 25 µM 1 , 2 , 3 and 4 in the absence ( a ) and presence of 6.25 µM ( b ), 12.5 µM ( c ), 25 µM ( d ), 50 µM ( e ), 100 µM ( f ), 200 µM ( g ), 800 µM ( i ) DNA.…”
Section: Resultsmentioning
confidence: 87%
“…The hypochromic effect of 1 and 3 contributed to the intercalation of 1 and 3 into the DNA base pairs and can be explained by decreasing the distance between DNA bases and intercalated 1 or 3. Overall, the observed binding www.nature.com/scientificreports/ constant of the complexes against DNA and 5FU where binding constant were reported to be 5.73 × 10 4 M −1 and 9.7 × 10 4 M −1 , respectively 59,60 .…”
Section: Resultsmentioning
confidence: 87%
“…This situation may be because Ag + ion is diamagnetic and Ni 2+ ion does not signal because it has short relaxation times at room temperature. EPR spectrum analyzes of Ni 2+ ioncontaining complexes reveal that EPR signals cannot be obtained at room temperature, but very low-intensity peaks can be seen at very low temperatures 60 .…”
Four new dicyanoargentate(I)-based complexes 1-4 were synthesized from certain metal ions with a tetradentate ligand [N, N-bis (2-hydroxyethyl)-ethylenediamine; N-bishydeten] and determined by diverse procedures (elemental, thermal, FT-IR, ESI-MS for 1-3 and, magnetic susceptibility and EPR for 1, and 2) including crystal analysis of 4. The crystal method revealed that complex 4 has a sandwich-type like polymeric chemical structure with layers formed by [Cd(N-bishydeten) 2 ] 2+ cations and [Ag(CN) 2 ] − anions. The complexes were further characterized by fluorescence and UV spectroscopy to determine their physicochemical features. The complexes displayed a DNA binding activity within the same range as found for cisplatin, in addition to their strong stability in the presence of the physiological buffer system. The complexes were also investigated for pharmacological properties like interaction with DNA/Bovine serum albumin, anticancer and antibacterial activities. Physicochemical studies of DNA with the complexes suggested that the interaction mode between them are possibly both intercalative and groove binding types. These spectroscopic measurements also show that there may be a binding tendency between BSA and the complexes via hydrogen or Van der Waals bonds. The viability tests demonstrated that all the complexes exhibited antibacterial (1-4) and anticancer effects (2-4) toward ten diverse bacterial strains and three tumor cells (HT-29 colon adenocarcinoma, HeLa cervical cancer, and C6 glioma), respectively. Despite the current advances in cancer therapy, the death rate from cancer and therapeutic agents are still increasing 1. A significant number of studies have focused on the synthesis and design of a new antiproliferative agent to reduce the risk of drug resistance and cell toxicity 2-4. Some of these studies are related to metallo compounds which constitute a significant part of agents with potent pharmacological activities, and their medicinal availability has been still explored 5,6. For example, some macrocyclic polyamines containing Ni, Cu, and Ru could recognize TAR RNA molecules and cleave them, and affect the interaction of Tat-RNA 7. Mn(II) complex of 2H-5-hydroxy-1,2,5-oxadiazo[3,4-f]1,10-phenanthroline has significant antitumor activity against HL-60, KB, Hela and BGC-823 cells.
“…The hypochromic effect of 1 and 3 contributed to the intercalation of 1 and 3 into the DNA base pairs and can be explained by decreasing the distance between DNA bases and intercalated 1 or 3 . Overall, the observed binding constant of the complexes against DNA and 5FU where binding constant were reported to be 5.73 × 10 4 M −1 and 9.7 × 10 4 M −1 , respectively 59 , 60 . Figure 5 UV absorption spectra of 25 µM 1 , 2 , 3 and 4 in the absence ( a ) and presence of 6.25 µM ( b ), 12.5 µM ( c ), 25 µM ( d ), 50 µM ( e ), 100 µM ( f ), 200 µM ( g ), 800 µM ( i ) DNA.…”
Section: Resultsmentioning
confidence: 87%
“…The hypochromic effect of 1 and 3 contributed to the intercalation of 1 and 3 into the DNA base pairs and can be explained by decreasing the distance between DNA bases and intercalated 1 or 3. Overall, the observed binding www.nature.com/scientificreports/ constant of the complexes against DNA and 5FU where binding constant were reported to be 5.73 × 10 4 M −1 and 9.7 × 10 4 M −1 , respectively 59,60 .…”
Section: Resultsmentioning
confidence: 87%
“…This situation may be because Ag + ion is diamagnetic and Ni 2+ ion does not signal because it has short relaxation times at room temperature. EPR spectrum analyzes of Ni 2+ ioncontaining complexes reveal that EPR signals cannot be obtained at room temperature, but very low-intensity peaks can be seen at very low temperatures 60 .…”
Four new dicyanoargentate(I)-based complexes 1-4 were synthesized from certain metal ions with a tetradentate ligand [N, N-bis (2-hydroxyethyl)-ethylenediamine; N-bishydeten] and determined by diverse procedures (elemental, thermal, FT-IR, ESI-MS for 1-3 and, magnetic susceptibility and EPR for 1, and 2) including crystal analysis of 4. The crystal method revealed that complex 4 has a sandwich-type like polymeric chemical structure with layers formed by [Cd(N-bishydeten) 2 ] 2+ cations and [Ag(CN) 2 ] − anions. The complexes were further characterized by fluorescence and UV spectroscopy to determine their physicochemical features. The complexes displayed a DNA binding activity within the same range as found for cisplatin, in addition to their strong stability in the presence of the physiological buffer system. The complexes were also investigated for pharmacological properties like interaction with DNA/Bovine serum albumin, anticancer and antibacterial activities. Physicochemical studies of DNA with the complexes suggested that the interaction mode between them are possibly both intercalative and groove binding types. These spectroscopic measurements also show that there may be a binding tendency between BSA and the complexes via hydrogen or Van der Waals bonds. The viability tests demonstrated that all the complexes exhibited antibacterial (1-4) and anticancer effects (2-4) toward ten diverse bacterial strains and three tumor cells (HT-29 colon adenocarcinoma, HeLa cervical cancer, and C6 glioma), respectively. Despite the current advances in cancer therapy, the death rate from cancer and therapeutic agents are still increasing 1. A significant number of studies have focused on the synthesis and design of a new antiproliferative agent to reduce the risk of drug resistance and cell toxicity 2-4. Some of these studies are related to metallo compounds which constitute a significant part of agents with potent pharmacological activities, and their medicinal availability has been still explored 5,6. For example, some macrocyclic polyamines containing Ni, Cu, and Ru could recognize TAR RNA molecules and cleave them, and affect the interaction of Tat-RNA 7. Mn(II) complex of 2H-5-hydroxy-1,2,5-oxadiazo[3,4-f]1,10-phenanthroline has significant antitumor activity against HL-60, KB, Hela and BGC-823 cells.
“…For the reactions between Ni 2+ and L n py , both the spectrophotometric changes and the kinetics indicate that these reactions go essentially to completion (Experimental section). The associated rate law for the reactions is eqn (5).…”
Section: Kinetic Studies On the Reactions Of Nimentioning
confidence: 99%
“…Similar behaviour, in which a metal ion initially binds at one site before moving to its final residence, has been observed with other polytopic ligands. 5,6 Important questions which need to be addressed are whether binding of metal ions to multidentate ligands (containing various types of donors) involves preferential binding at a specific site, and whether this can be detected using kinetics. In this paper we report kinetic studies on the reactions of [Ni(MeOH) 6 ] 2+ (hereafter written as Ni 2+ ) with a variety of neutral multidentate Schiff base ligands (Fig.…”
The kinetics of the reactions between [Ni(MeOH)6](2+) (hereafter Ni(2+)) and a variety of neutral Schiff base multidentate ligands have been measured in methanol at 25.0 °C using stopped-flow spectrophotometry. The ligands contain a variety of different potential donor sites (phenolic OH, imine N, pyridyl N and NH groups), different structural components and substituents. The kinetic studies explore how systematic changes to the composition of the ligands affect the rates of binding. The results are consistent with the Eigen-Wilkins mechanism in which the ligand initially forms an outer-sphere association with Ni(2+) prior to dissociation of a coordinated solvent molecule and binding to the metal ion. The general features that emerge from these studies are as follows. (i) For ligands with the same donor set, the rates of binding are all similar irrespective of changes to the ligand framework (bridge and substituents). (ii) Comparison of structurally analogous ligands shows that the presence of pyridyl or NH groups in the multidentate results in significantly faster reactions. (iii) With ligands containing multiple NH groups, the rate of ligand binding increases as the number of NH groups increases. The extent to which these kinetic features can be attributed to preferential binding of particular donor groups is discussed.
Short-lived radioactive isotopes (SLRs) with half-lives between 0.1 to 100 Myr can be used to probe the origin of the Solar System. In this work, we examine the core-collapse supernovae production of the 15 SLRs produced: 26
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