Achilleas Garoufis - Academia.edu (original) (raw)
Papers by Achilleas Garoufis
European Journal of Inorganic Chemistry, 2000
The interactions between diethyltin dichloride and 5'-CMP, 5'-dCMP, and 5'-UMP in aqueous solutio... more The interactions between diethyltin dichloride and 5'-CMP, 5'-dCMP, and 5'-UMP in aqueous solution were investigated by multinuclear 1D and 2D NMR techniques including 119 Sn, 15 N and 31 P nuclei. These studies were combined with electrospray mass spectrometry, infrared spectroscopy, solid state 13 C, 31 P and 117 Sn CP-MAS NMR, and elemental analysis. As demonstrated by 31 P-1 H HOESY spectroscopy, the diethyltin moiety interacts with the phosphate group of the pyrimidic mononucleotides in the pH range 0.5-3.5. Compound 8 (X = Cl), the solid isolated in this pH range from 5'-CMP, contains two tin atoms bridged by one oxygen and one chlorine atom,
Coordination Chemistry Reviews, 2009
Pd(II) complexes of various donor atom ligands posses anti-tumor and anti-viral, -malarial, -fung... more Pd(II) complexes of various donor atom ligands posses anti-tumor and anti-viral, -malarial, -fungal and -microbial activities. This review focuses on such properties of Pd(II) complexes and makes comparisons with similar properties of other metals. In the first part, the anti-viral, anti-fungal and anti-microbial activities of new Pd(II) complexes are described, classified according to the ligands used, namely; sulfur donors, ligands
![Research paper thumbnail of Synthesis and characterization of Pd(II) and Pt(II) complexes with triazolopyrimidine derivatives: The crystal structure of [Pd2L2Cl4] where L=5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine](https://attachments.academia-assets.com/65566289/thumbnails/1.jpg)
](Inorganica Chimica Acta, 2006
The Pd(II) and Pt(II) complexes with triazolopyrimidine C-nucleosides L 1 (5,7-dimethyl-3-(2 0 ,3... more The Pd(II) and Pt(II) complexes with triazolopyrimidine C-nucleosides L 1 (5,7-dimethyl-3-(2 0 ,3 0 ,5 0 -tri-O-benzoyl-b-D-ribofuranosyl-striazolo)[4,3-a]pyrimidine), L 2 (5,7-dimethyl-3-b-D-ribofuranosyl-s-triazolo[4,3-a]pyrimidine) and L 3 (5,7-dimethyl[1,5-a]-s-triazolopyrimidine), [Pd(en)(L 1 )](NO 3 ) 2 , [Pd(bpy)(L 1 )](NO 3 ) 2 , cis-Pd(L 3 ) 2 Cl 2 , [Pd 2 (L 3 ) 2 Cl 4 ] AE H 2 O, cis-Pd(L 2 ) 2 Cl 2 and [Pt 3 (L 1 ) 2 Cl 6 ] were synthesized and characterized by elemental analysis and NMR spectroscopy. The structure of the [Pd 2 (L 3 ) 2 Cl 4 ] AE H 2 O complex was established by Xray crystallography. The two L 3 ligands are found in a head to tail orientation, with a PdÁ Á ÁPd distance of 3.1254(17) Å . L 1 coordinates to Pd(II) through N8 and N1 forming polymeric structures. L 2 coordinates to Pd(II) through N8 in acidic solutions (0.1 M HCl) forming complexes of cis-geometry. The Pd(II) coordination to L 2 does not affect the sugar conformation probably due to the high stability of the C-C glycoside bond.
Acta Chemica Scandinavica, 1995
Dalton Transactions, 2011
The synthesis, characterization and DNA binding properties of the complex [Ru(terpy)(4,4¢-(COLysC... more The synthesis, characterization and DNA binding properties of the complex [Ru(terpy)(4,4¢-(COLysCONH 2 ) 2 bpy)Cl] 3+ (1) have been studied. Complex (1) hydrolyzes to (2) with a calculated rate constant K h = 2.35 ± 0.08 ¥ 10 -4 s -1 and binds coordinatively to ct-DNA, with a saturation r-value at about 0.1. Stabilization of the ct-DNA helix at low electrolyte (NaClO 4 ) concentration (10 mM) and destabilization at higher electrolyte concentrations (50-200 mM) was observed. Circular dichroism studies indicate that the hydrolyzed complex binds to DNA, increasing the unwinding of the DNA helix with an unwinding angle calculated as U = 12 ± 2 • . The positive LD signal observed at 350 nm indicates some kind of specificity in complex orientation towards the global DNA axis. Complex (2) binds specifically to G4 on the central part of the oligonucleotide duplexes d(CGCGCG) 2 and d(GTCGAC) 2 , as evidenced by NMR spectroscopy. Both lysine moieties were found to interact most likely electrostatically with the DNA phosphates, assisting the coordinative binding and increasing the DNA affinity of the complex. Photoinduced DNA cleavage by (2), upon UVA irradiation was observed, but despite its relative high DNA affinity, it was incomplete (~12%).
Dalton Transactions, 2009
Diastereomeric oligopyridine-ruthenium(II)-amino acid conjugated complexes of the general formula... more Diastereomeric oligopyridine-ruthenium(II)-amino acid conjugated complexes of the general formulas K-and D-[Ru(bpy) 2 (4,4¢(CO 2 Y) 2 -bpy)] 2+ , where Y = L-AlaCONH 2 , L-LysCONH 2 , L-HisCONH 2 , L-TyrCONH 2 ), were synthesized and characterized. Their binding properties with ct-DNA and the oligonucleotide duplex d(5¢CGCGCG-3¢) 2 , by means of circular dichroism (CD), NMR spectroscopy and DNA thermal denaturation (T m ) curves were studied. CD and T m data indicate that all diastereomeric complexes bind to the DNA major groove, D-diastereomers in a similar manner, while K-diastereomers in dependence of the nature of the amino acid. NMR studies of d(5¢CGCGCG-3¢) 2 , and the complexes D-1, D-2, K-1 and K-2 indicate that D-1 and D-2 were bound having the ancillary bpy ligands towards the DNA groove, while the corresponding K-1 and K-2 were orientated in a similar way, facing the ligand 4,4¢(CO 2 Y) 2 bpy towards the DNA major groove. Photoinduced DNA cleavage was observed in all cases studied, which take place through singlet oxygen production. D-4 and K-4 show the lower photoinduced cleavage yield, probably because the singlet oxygen ( 1 O 2 ) oxidizes not only the DNA phosporodiesteric bonds but the tyrosine's phenolic OH bond as well.
![Research paper thumbnail of NMR analysis of duplex d(CGCGATCGCG)2 modified by Λ- and Δ-[Ru(bpy)2(m-GHK)]Cl2 and DNA photocleavage study](https://attachments.academia-assets.com/44462284/thumbnails/1.jpg)
](JBIC Journal of Biological Inorganic Chemistry, 2007
Journal of inorganic biochemistry
Diastereomeric complexes of the general formulae Λ- and Δ-[Ru(bpy)2(4-COY-4'-Mebpy)]Cl2 where... more Diastereomeric complexes of the general formulae Λ- and Δ-[Ru(bpy)2(4-COY-4'-Mebpy)]Cl2 where bpy=2,2'-bipyridine and Y=Gly-Lys(1)-Lys(2)CONH2, Lys(1)-Gly-Lys(2)CONH2, Lys(1)-Lys(2)-GlyCONH2, were synthesized and characterized. The ability of these compounds to bind to the oligonucleotide duplex d(5'-CGCGAATTCGCG-3') was studied with NMR techniques. Complex Λ-2, Λ-[Ru(bpy)2(4-COLys(1)-Gly-Lys(2)CONH2),4'-Mebpy)]Cl2 (Mebpy=methyl-2,2'-bipyridine), interacts non-specifically causing changes for both complex and oligonucleotide (1)H NMR signals. Both Λ-1, Λ-[Ru(bpy)2(4-COGly-Lys(1)-Lys(2)CONH2),4'-Mebpy)]Cl2 and Λ-3, Λ-[Ru(bpy)2(4-COLys(1)-Lys(2)-GlyCONH2),4'-Mebpy)]Cl2, were bound to the oligonucleotide through both lysine aliphatic chains, indicating that the side chains of the sequential lysines create a kind of "clamp" to connect the complex with the oligonucleotide. Complex Δ-1, Δ-[Ru(bpy)2(4-COGly-Lys(1)-Lys(2)CONH2),4'-Mebpy)]Cl2, in...
... J. Inorg. Nucl. Chem. 37 (1975), p. 23. 14b. GV Fazakerley and JC Russel. J. Inorg. Nucl. Che... more ... J. Inorg. Nucl. Chem. 37 (1975), p. 23. 14b. GV Fazakerley and JC Russel. J. Inorg. Nucl. Chem. 37 (1975), p. 77. 15. ... J. Inorg. Nucl. Chem. 27 (1973), p. 1063. 18. A. Shamim, A. Adeyemo, MTShamim, J. Wheeler, A. Turner and AB Hussein. Inorg. Chim. Acta 91 (1984), p. 179. ...
The DNA-binding properties of a number of ruthenium oligopyridine complexes with conjugated amino... more The DNA-binding properties of a number of ruthenium oligopyridine complexes with conjugated amino acids having the general formulae [Ru(terpy)(4-COY-4 0 -Mebpy)(X)] n+ , X = NO (n = 3), X = Cl (n = 1) and NO 2 (n = 1) and Y = AlaCONH 2 and TrpCONH 2 are reported. The new complexes were spectroscopically characterized and their DNA-binding properties were studied by means of circular dichroism (CD), 23 Na and 31 P NMR spectroscopy. The results show that the chlorido complexes interact by coordination to the DNA bases with the conjugated amino acid able to provide an additional interaction with the DNA helix. In addition, electrostatic interactions between all studied complexes and the DNA polyanion were observed. The nitro complexes were found to be insignificant, affecting only the 31 P NMR signal, probably due to changes in the hydration sphere of the DNA close to the phosphates.
Acta Chemica Scandinavica, 1995
Polyhedron, 1995
Ternary complexes of formulae [Cu(dipeptide)(nucl)2]C12 • xH20 with dipeptides glycyl-glycine (Gl... more Ternary complexes of formulae [Cu(dipeptide)(nucl)2]C12 • xH20 with dipeptides glycyl-glycine (Gly-Gly), glycyl-L-alanine (Gly-Ala), glycyl-L-valine (Gly-Val), glycyl-L-leucine (Gly-Leu) and nucl inosine (ino) and guanosine (guo) were isolated from a water:ethanol (2: 1) solution and characterized with elemental analysis, conductivity measurements, IR, electronic and ESR spectra. At low pH values (<4) the dipeptides coordinate through the (--NH2) terminal and peptide (C------O) groups and the nucleosides through the N 7 atoms. At pH > 4 the dipeptides coordinate through the (--NH2) terminal and the deprotonated amide (--N-) groups. The pKa values for these deprotonations were estimated with electronic spectra and increase with the increase of the side chain of the dipeptides, due to steric reasons. At higher pH values one nucleoside molecule is liberated and replaced by the terminal deprotonated carboxylate group of the dipeptides. The pK values for these transformations were calculated with ESR spectra and follow the same trend as for the deprotonation constants and for the same reason.
Journal of Organometallic Chemistry, 2014
ABSTRACT Ruthenium eta(6)-arene compounds of the general formula [(eta(6)-arene)Ru(L)Cl](PF6), (1... more ABSTRACT Ruthenium eta(6)-arene compounds of the general formula [(eta(6)-arene)Ru(L)Cl](PF6), (1)PF6-(4)PF6, (eta(6)-arene is benzene (bz) or p-cymene (cym), L is 2-(2'-pyridyl)quinoxaline (pqx) or 2-(2'-pyridyl)benzo [g] quinoxaline (pbqx)) and [(eta(6)-cym)Ru(L)(9MeG)](PF6)(2), (L is 2-(2'-pyridyl)quinoxaline (pqx), 2-(2'-pyridyl)benzo [g]quinoxaline (pbqx), 2,2'-bipyridine (bpy), 9MeG is 9-methylguanine), (5)(PF6)(2)-(7)(PF6)(2), were synthesized and characterized by spectroscopic and analytical techniques. The molecular structures of the complexes (1) (4), determined by single-crystal X-ray analysis of the hexafluorophospate salts, are also reported. In (5)(PF6)(2)-(7)(PF6)(2), the nucleobase 9MeG binds to ruthenium through N7. Based on H-1 NMR spectroscopy, a strong shielding effect between the aromatic ring system of the quinoxaline or benzo[g]quinoxaline moiety of the ligands pqx and pbqx and the H8 of 9MeG was observed. The complexes (1) (4) are highly cytotoxic as chloride salts, against various cancer cell lines, with their IC50 values observed at less than 1 mu M.
Polyhedron, 1999
Complexes of 2-(2′-pyridyl)quinoxaline (L) with R2SnCl2 (R=Me, Et, Bun) have been synthesized and... more Complexes of 2-(2′-pyridyl)quinoxaline (L) with R2SnCl2 (R=Me, Et, Bun) have been synthesized and characterized using IR, far-IR, 119Sn Mössbauer, 1H and 13C spectroscopies. The X-ray crystal structure of Et2SnCl2L shows a bidentate chelating behaviour of L, which is observed in all the diorganotin compounds presented. Interaction of the ligand L with SnCl4 resulted in the formation of a salt with
Journal of Molecular Structure, 2015
ABSTRACT 2-Methyl-2,4-di-thiophen-2′,2″-yl-2,3-dihydro-1H-benzo[b][1,4]diazepine (L) has been syn... more ABSTRACT 2-Methyl-2,4-di-thiophen-2′,2″-yl-2,3-dihydro-1H-benzo[b][1,4]diazepine (L) has been synthesized through condensation of phenylene-1,2-diamine and 2-acetylthiophene, and its reactions with dialkyltin(IV)dichlorides have been studied. Two salts formulated as (LH)[R2SnCl3] (R = Et, 1; R = Me, 2) have been isolated. L and 1 were structurally characterized. The conformation of the benzodiazepine L, changes in 1 due to H-bonds formation. [Et2SnCl3]- is one of the rare examples of five coordinated tin(IV) species and has distorted trigonal bipyramidal geometry. H-bonding interactions, in 1, lead to the formation of supramolecular helices.
Transition Metal Chemistry, 1993
Transition metal(II) chloro complexes of the new Schiff base ligand 1,2-bis(2'-pyridylmethyleneim... more Transition metal(II) chloro complexes of the new Schiff base ligand 1,2-bis(2'-pyridylmethyleneimino)benzene (L), derived from 2-pyridinecarboxaldehyde and 1,2-phenylenediamine, were prepared. Compounds of [MnLC12]. HzO, [CoLC12]'2H20, [NiLCI2] and [Zn3LzCI4]C12 were prepared. Details are given of the formation of the complex [Cu(L" EtOH)C12], in which one molecule of EtOH adds across only one of the Schiff base C:N groups to give the coordinated ligand L.
Polyhedron, 1996
The 1 : 1 reaction of Hg(C104)2" 3H20 with 2-(2'-pyridyl)quinoxaline(L) in acetone leads to isola... more The 1 : 1 reaction of Hg(C104)2" 3H20 with 2-(2'-pyridyl)quinoxaline(L) in acetone leads to isolation of [Hg(CH2COCH3)(C104)L]2; the X-ray crystal structure determination together with 1H-and 13C-NMR spectra reveal the presence of the coordinated 2-0xopropyl anion. L coordinates in a bidentate, highly asymmetric mode.
Polyhedron, 1998
... Achilleas Garoufis 1 , Corresponding Author Contact Information , Spyridoula Kasselouri 1 , C... more ... Achilleas Garoufis 1 , Corresponding Author Contact Information , Spyridoula Kasselouri 1 , Catherine P. Raptopoulou 2 and Aris Terzis 2. ... Extensive studies [42] have shown that the scharacter of the nitrogen lone pair in the C=N bond increases upon coordination, producing a ...
European Journal of Inorganic Chemistry, 2000
The interactions between diethyltin dichloride and 5'-CMP, 5'-dCMP, and 5'-UMP in aqueous solutio... more The interactions between diethyltin dichloride and 5'-CMP, 5'-dCMP, and 5'-UMP in aqueous solution were investigated by multinuclear 1D and 2D NMR techniques including 119 Sn, 15 N and 31 P nuclei. These studies were combined with electrospray mass spectrometry, infrared spectroscopy, solid state 13 C, 31 P and 117 Sn CP-MAS NMR, and elemental analysis. As demonstrated by 31 P-1 H HOESY spectroscopy, the diethyltin moiety interacts with the phosphate group of the pyrimidic mononucleotides in the pH range 0.5-3.5. Compound 8 (X = Cl), the solid isolated in this pH range from 5'-CMP, contains two tin atoms bridged by one oxygen and one chlorine atom,
Coordination Chemistry Reviews, 2009
Pd(II) complexes of various donor atom ligands posses anti-tumor and anti-viral, -malarial, -fung... more Pd(II) complexes of various donor atom ligands posses anti-tumor and anti-viral, -malarial, -fungal and -microbial activities. This review focuses on such properties of Pd(II) complexes and makes comparisons with similar properties of other metals. In the first part, the anti-viral, anti-fungal and anti-microbial activities of new Pd(II) complexes are described, classified according to the ligands used, namely; sulfur donors, ligands
Inorganica Chimica Acta, 2006
The Pd(II) and Pt(II) complexes with triazolopyrimidine C-nucleosides L 1 (5,7-dimethyl-3-(2 0 ,3... more The Pd(II) and Pt(II) complexes with triazolopyrimidine C-nucleosides L 1 (5,7-dimethyl-3-(2 0 ,3 0 ,5 0 -tri-O-benzoyl-b-D-ribofuranosyl-striazolo)[4,3-a]pyrimidine), L 2 (5,7-dimethyl-3-b-D-ribofuranosyl-s-triazolo[4,3-a]pyrimidine) and L 3 (5,7-dimethyl[1,5-a]-s-triazolopyrimidine), [Pd(en)(L 1 )](NO 3 ) 2 , [Pd(bpy)(L 1 )](NO 3 ) 2 , cis-Pd(L 3 ) 2 Cl 2 , [Pd 2 (L 3 ) 2 Cl 4 ] AE H 2 O, cis-Pd(L 2 ) 2 Cl 2 and [Pt 3 (L 1 ) 2 Cl 6 ] were synthesized and characterized by elemental analysis and NMR spectroscopy. The structure of the [Pd 2 (L 3 ) 2 Cl 4 ] AE H 2 O complex was established by Xray crystallography. The two L 3 ligands are found in a head to tail orientation, with a PdÁ Á ÁPd distance of 3.1254(17) Å . L 1 coordinates to Pd(II) through N8 and N1 forming polymeric structures. L 2 coordinates to Pd(II) through N8 in acidic solutions (0.1 M HCl) forming complexes of cis-geometry. The Pd(II) coordination to L 2 does not affect the sugar conformation probably due to the high stability of the C-C glycoside bond.
Acta Chemica Scandinavica, 1995
Dalton Transactions, 2011
The synthesis, characterization and DNA binding properties of the complex [Ru(terpy)(4,4¢-(COLysC... more The synthesis, characterization and DNA binding properties of the complex [Ru(terpy)(4,4¢-(COLysCONH 2 ) 2 bpy)Cl] 3+ (1) have been studied. Complex (1) hydrolyzes to (2) with a calculated rate constant K h = 2.35 ± 0.08 ¥ 10 -4 s -1 and binds coordinatively to ct-DNA, with a saturation r-value at about 0.1. Stabilization of the ct-DNA helix at low electrolyte (NaClO 4 ) concentration (10 mM) and destabilization at higher electrolyte concentrations (50-200 mM) was observed. Circular dichroism studies indicate that the hydrolyzed complex binds to DNA, increasing the unwinding of the DNA helix with an unwinding angle calculated as U = 12 ± 2 • . The positive LD signal observed at 350 nm indicates some kind of specificity in complex orientation towards the global DNA axis. Complex (2) binds specifically to G4 on the central part of the oligonucleotide duplexes d(CGCGCG) 2 and d(GTCGAC) 2 , as evidenced by NMR spectroscopy. Both lysine moieties were found to interact most likely electrostatically with the DNA phosphates, assisting the coordinative binding and increasing the DNA affinity of the complex. Photoinduced DNA cleavage by (2), upon UVA irradiation was observed, but despite its relative high DNA affinity, it was incomplete (~12%).
Dalton Transactions, 2009
Diastereomeric oligopyridine-ruthenium(II)-amino acid conjugated complexes of the general formula... more Diastereomeric oligopyridine-ruthenium(II)-amino acid conjugated complexes of the general formulas K-and D-[Ru(bpy) 2 (4,4¢(CO 2 Y) 2 -bpy)] 2+ , where Y = L-AlaCONH 2 , L-LysCONH 2 , L-HisCONH 2 , L-TyrCONH 2 ), were synthesized and characterized. Their binding properties with ct-DNA and the oligonucleotide duplex d(5¢CGCGCG-3¢) 2 , by means of circular dichroism (CD), NMR spectroscopy and DNA thermal denaturation (T m ) curves were studied. CD and T m data indicate that all diastereomeric complexes bind to the DNA major groove, D-diastereomers in a similar manner, while K-diastereomers in dependence of the nature of the amino acid. NMR studies of d(5¢CGCGCG-3¢) 2 , and the complexes D-1, D-2, K-1 and K-2 indicate that D-1 and D-2 were bound having the ancillary bpy ligands towards the DNA groove, while the corresponding K-1 and K-2 were orientated in a similar way, facing the ligand 4,4¢(CO 2 Y) 2 bpy towards the DNA major groove. Photoinduced DNA cleavage was observed in all cases studied, which take place through singlet oxygen production. D-4 and K-4 show the lower photoinduced cleavage yield, probably because the singlet oxygen ( 1 O 2 ) oxidizes not only the DNA phosporodiesteric bonds but the tyrosine's phenolic OH bond as well.
JBIC Journal of Biological Inorganic Chemistry, 2007
Journal of inorganic biochemistry
Diastereomeric complexes of the general formulae Λ- and Δ-[Ru(bpy)2(4-COY-4'-Mebpy)]Cl2 where... more Diastereomeric complexes of the general formulae Λ- and Δ-[Ru(bpy)2(4-COY-4'-Mebpy)]Cl2 where bpy=2,2'-bipyridine and Y=Gly-Lys(1)-Lys(2)CONH2, Lys(1)-Gly-Lys(2)CONH2, Lys(1)-Lys(2)-GlyCONH2, were synthesized and characterized. The ability of these compounds to bind to the oligonucleotide duplex d(5'-CGCGAATTCGCG-3') was studied with NMR techniques. Complex Λ-2, Λ-[Ru(bpy)2(4-COLys(1)-Gly-Lys(2)CONH2),4'-Mebpy)]Cl2 (Mebpy=methyl-2,2'-bipyridine), interacts non-specifically causing changes for both complex and oligonucleotide (1)H NMR signals. Both Λ-1, Λ-[Ru(bpy)2(4-COGly-Lys(1)-Lys(2)CONH2),4'-Mebpy)]Cl2 and Λ-3, Λ-[Ru(bpy)2(4-COLys(1)-Lys(2)-GlyCONH2),4'-Mebpy)]Cl2, were bound to the oligonucleotide through both lysine aliphatic chains, indicating that the side chains of the sequential lysines create a kind of "clamp" to connect the complex with the oligonucleotide. Complex Δ-1, Δ-[Ru(bpy)2(4-COGly-Lys(1)-Lys(2)CONH2),4'-Mebpy)]Cl2, in...
... J. Inorg. Nucl. Chem. 37 (1975), p. 23. 14b. GV Fazakerley and JC Russel. J. Inorg. Nucl. Che... more ... J. Inorg. Nucl. Chem. 37 (1975), p. 23. 14b. GV Fazakerley and JC Russel. J. Inorg. Nucl. Chem. 37 (1975), p. 77. 15. ... J. Inorg. Nucl. Chem. 27 (1973), p. 1063. 18. A. Shamim, A. Adeyemo, MTShamim, J. Wheeler, A. Turner and AB Hussein. Inorg. Chim. Acta 91 (1984), p. 179. ...
The DNA-binding properties of a number of ruthenium oligopyridine complexes with conjugated amino... more The DNA-binding properties of a number of ruthenium oligopyridine complexes with conjugated amino acids having the general formulae [Ru(terpy)(4-COY-4 0 -Mebpy)(X)] n+ , X = NO (n = 3), X = Cl (n = 1) and NO 2 (n = 1) and Y = AlaCONH 2 and TrpCONH 2 are reported. The new complexes were spectroscopically characterized and their DNA-binding properties were studied by means of circular dichroism (CD), 23 Na and 31 P NMR spectroscopy. The results show that the chlorido complexes interact by coordination to the DNA bases with the conjugated amino acid able to provide an additional interaction with the DNA helix. In addition, electrostatic interactions between all studied complexes and the DNA polyanion were observed. The nitro complexes were found to be insignificant, affecting only the 31 P NMR signal, probably due to changes in the hydration sphere of the DNA close to the phosphates.
Acta Chemica Scandinavica, 1995
Polyhedron, 1995
Ternary complexes of formulae [Cu(dipeptide)(nucl)2]C12 • xH20 with dipeptides glycyl-glycine (Gl... more Ternary complexes of formulae [Cu(dipeptide)(nucl)2]C12 • xH20 with dipeptides glycyl-glycine (Gly-Gly), glycyl-L-alanine (Gly-Ala), glycyl-L-valine (Gly-Val), glycyl-L-leucine (Gly-Leu) and nucl inosine (ino) and guanosine (guo) were isolated from a water:ethanol (2: 1) solution and characterized with elemental analysis, conductivity measurements, IR, electronic and ESR spectra. At low pH values (<4) the dipeptides coordinate through the (--NH2) terminal and peptide (C------O) groups and the nucleosides through the N 7 atoms. At pH > 4 the dipeptides coordinate through the (--NH2) terminal and the deprotonated amide (--N-) groups. The pKa values for these deprotonations were estimated with electronic spectra and increase with the increase of the side chain of the dipeptides, due to steric reasons. At higher pH values one nucleoside molecule is liberated and replaced by the terminal deprotonated carboxylate group of the dipeptides. The pK values for these transformations were calculated with ESR spectra and follow the same trend as for the deprotonation constants and for the same reason.
Journal of Organometallic Chemistry, 2014
ABSTRACT Ruthenium eta(6)-arene compounds of the general formula [(eta(6)-arene)Ru(L)Cl](PF6), (1... more ABSTRACT Ruthenium eta(6)-arene compounds of the general formula [(eta(6)-arene)Ru(L)Cl](PF6), (1)PF6-(4)PF6, (eta(6)-arene is benzene (bz) or p-cymene (cym), L is 2-(2'-pyridyl)quinoxaline (pqx) or 2-(2'-pyridyl)benzo [g] quinoxaline (pbqx)) and [(eta(6)-cym)Ru(L)(9MeG)](PF6)(2), (L is 2-(2'-pyridyl)quinoxaline (pqx), 2-(2'-pyridyl)benzo [g]quinoxaline (pbqx), 2,2'-bipyridine (bpy), 9MeG is 9-methylguanine), (5)(PF6)(2)-(7)(PF6)(2), were synthesized and characterized by spectroscopic and analytical techniques. The molecular structures of the complexes (1) (4), determined by single-crystal X-ray analysis of the hexafluorophospate salts, are also reported. In (5)(PF6)(2)-(7)(PF6)(2), the nucleobase 9MeG binds to ruthenium through N7. Based on H-1 NMR spectroscopy, a strong shielding effect between the aromatic ring system of the quinoxaline or benzo[g]quinoxaline moiety of the ligands pqx and pbqx and the H8 of 9MeG was observed. The complexes (1) (4) are highly cytotoxic as chloride salts, against various cancer cell lines, with their IC50 values observed at less than 1 mu M.
Polyhedron, 1999
Complexes of 2-(2′-pyridyl)quinoxaline (L) with R2SnCl2 (R=Me, Et, Bun) have been synthesized and... more Complexes of 2-(2′-pyridyl)quinoxaline (L) with R2SnCl2 (R=Me, Et, Bun) have been synthesized and characterized using IR, far-IR, 119Sn Mössbauer, 1H and 13C spectroscopies. The X-ray crystal structure of Et2SnCl2L shows a bidentate chelating behaviour of L, which is observed in all the diorganotin compounds presented. Interaction of the ligand L with SnCl4 resulted in the formation of a salt with
Journal of Molecular Structure, 2015
ABSTRACT 2-Methyl-2,4-di-thiophen-2′,2″-yl-2,3-dihydro-1H-benzo[b][1,4]diazepine (L) has been syn... more ABSTRACT 2-Methyl-2,4-di-thiophen-2′,2″-yl-2,3-dihydro-1H-benzo[b][1,4]diazepine (L) has been synthesized through condensation of phenylene-1,2-diamine and 2-acetylthiophene, and its reactions with dialkyltin(IV)dichlorides have been studied. Two salts formulated as (LH)[R2SnCl3] (R = Et, 1; R = Me, 2) have been isolated. L and 1 were structurally characterized. The conformation of the benzodiazepine L, changes in 1 due to H-bonds formation. [Et2SnCl3]- is one of the rare examples of five coordinated tin(IV) species and has distorted trigonal bipyramidal geometry. H-bonding interactions, in 1, lead to the formation of supramolecular helices.
Transition Metal Chemistry, 1993
Transition metal(II) chloro complexes of the new Schiff base ligand 1,2-bis(2'-pyridylmethyleneim... more Transition metal(II) chloro complexes of the new Schiff base ligand 1,2-bis(2'-pyridylmethyleneimino)benzene (L), derived from 2-pyridinecarboxaldehyde and 1,2-phenylenediamine, were prepared. Compounds of [MnLC12]. HzO, [CoLC12]'2H20, [NiLCI2] and [Zn3LzCI4]C12 were prepared. Details are given of the formation of the complex [Cu(L" EtOH)C12], in which one molecule of EtOH adds across only one of the Schiff base C:N groups to give the coordinated ligand L.
Polyhedron, 1996
The 1 : 1 reaction of Hg(C104)2" 3H20 with 2-(2'-pyridyl)quinoxaline(L) in acetone leads to isola... more The 1 : 1 reaction of Hg(C104)2" 3H20 with 2-(2'-pyridyl)quinoxaline(L) in acetone leads to isolation of [Hg(CH2COCH3)(C104)L]2; the X-ray crystal structure determination together with 1H-and 13C-NMR spectra reveal the presence of the coordinated 2-0xopropyl anion. L coordinates in a bidentate, highly asymmetric mode.
Polyhedron, 1998
... Achilleas Garoufis 1 , Corresponding Author Contact Information , Spyridoula Kasselouri 1 , C... more ... Achilleas Garoufis 1 , Corresponding Author Contact Information , Spyridoula Kasselouri 1 , Catherine P. Raptopoulou 2 and Aris Terzis 2. ... Extensive studies [42] have shown that the scharacter of the nitrogen lone pair in the C=N bond increases upon coordination, producing a ...