João Madureira - Academia.edu (original) (raw)
Papers by João Madureira
International Journal of Mass Spectrometry, 2011
Electrospray ionization mass spectrometry (ESIMS) was used to investigate the coordination modes ... more Electrospray ionization mass spectrometry (ESIMS) was used to investigate the coordination modes of the complexes [Ru II ([9]aneS 3 )(HCpz 3 )Cl]Cl, [Ru II ([9]aneS 3 )(HCpz 3 )](Cl)PF 6 and [Ru II ([9]aneS 3 )(HCpz 3 )](PF 6 ) 2 ([9]aneS 3 = 1,4,7-trithiacyclononane; HCpz 3 = tris(1-pyrazolyl)methane) in methanol, acetonitrile and methanol/water solutions. The complex [Ru II ([9]aneS 3 )(HCpz 3 )Cl]Cl shows a rapidly exchangeable Cl ligand, with formation of a doubly charged ion [Ru II ([9]aneS 3 )(HCpz 3 )] 2+ , m/z 248, but the [Ru II ([9]aneS 3 )(HCpz 3 )Cl] + , m/z 531, is also observed and both species still coexist after 16 h. The formation of the [Ru II ([9]aneS 3 )(HCpz 3 )] 2+ and [Ru II ([9]aneS 3 )(HCpz 3 )Cl] + ions by electrospraying solutions of [Ru II ([9]aneS 3 )(dmso)Cl 2 ] (dmso = dimethylsulfoxide) and HCpz 3 in water/methanol was also studied.
Inorganica Chimica Acta, 2003
The synthesis and structural characterisation of the complex [Cr ([14]aneN 4 )(O -dmso)Cl](PF 6 )... more The synthesis and structural characterisation of the complex [Cr ([14]aneN 4 )(O -dmso)Cl](PF 6 ) 2 ×/dmso is reported. The structural studies were carried out in gas-phase by electrospray mass spectrometry (ESMS) and in the solid state by single crystal X-ray diffraction. The metal complex shows a distorted octahedral coordination environment with the macrocycle adopting a folded cis -V conformation. The angle N axial Ã/CrÃ/N axial deviates by only 128 from the ideal value of 1808 for a perfect octahedron indicating that there is a good match between the size of the macrocyclic cavity and the size of Cr(III) ion. The ESMS shows that the complex loses a proton with concomitant opening of the aneN 4 ring to give the [Cr ([14]aneN 4 -H)(dmso)Cl] ' ion with a CH 2 Ä/CHÃ/ pendant chain. This group interacts with dmso leading to the loss of this ligand and to the formation of the [Cr ([14]aneN 4 -H)Cl] ' ion, which has the highest relative abundance (100%). DFT calculations reproduce the geometry of the paramagnetic complex and are consistent with its electronic spectrum. #
Journal of The Chemical Society-dalton Transactions, 2001
J. Chem. Soc., Dalton Trans., 2001, 1628-1633 DOI:10.1039/B101152I (Paper). Synthesis and charact... more J. Chem. Soc., Dalton Trans., 2001, 1628-1633 DOI:10.1039/B101152I (Paper). Synthesis and characterisation of a Ru II ([14]aneS 4 ) complex immobilised in MCM-41-type mesoporous silica. Martyn Pillingera, Isabel S. Gonçalves ...
Metal-based Drugs, 2001
The complexes [Ru ([9]aneS3)(dppz)Cl]Cl 1 and [Ru(II2]aneS4)(dppz)]Ci_ 2 ([9]aneS3=l,4,7 trithiac... more The complexes [Ru ([9]aneS3)(dppz)Cl]Cl 1 and [Ru(II2]aneS4)(dppz)]Ci_ 2 ([9]aneS3=l,4,7 trithiaciclononane and [12]aneS4=l,4,7,10-tetrathiaciclododecane) were synthesised and fully characterised. These complexes belong to a small family of dipyridophenazine complexes with non-polypyridyl ancillary ligands. Interaction studies of these complexes with CT-DNA (UV/Vis titrations, steady-state emission and thermal denaturation) revealed their high affinity for DNA. Intercalation constants determined by UV/Vis titrations are of the same order of magnitude (106) as other dppz metallointercalators, namely [Ru(II)(bpy)2dppz]2+. Differences between and 2 were identified by steady-state emission and thermal denaturation studies. Emission results are in accordance with structural data, which indicate how geometric distortions and different donor and/or acceptor ligand abilities affect luminescence. The possibility of noncovalent interactions between ancillary ligands and nucleobases by van der Waals contacts and H-bridges is discussed. Furthermore, complex undergoes aquation under intra-cellular conditions and an equilibrium with the aquated form I' is attained. This behaviour may increase the diversity of available interaction modes.
Journal of The Chemical Society-dalton Transactions, 2000
A large number of new [Ru II ([9]aneS 3 )(L)Cl] + complexes (where L is a polypyridyl bidentate l... more A large number of new [Ru II ([9]aneS 3 )(L)Cl] + complexes (where L is a polypyridyl bidentate ligand) were synthesized from the precursor [Ru([9]aneS 3 )(dmso)Cl 2 ] in the search for new DNA intercalators. The ancillary ligands used have different molecular architectures ...
International Journal of Mass Spectrometry, 2005
A new series of ruthenium(II) complexes with the general formula [Ru II ([12]aneS 4 )(NN)]X 2 , w... more A new series of ruthenium(II) complexes with the general formula [Ru II ([12]aneS 4 )(NN)]X 2 , where NN are bidentate diimines, [12]aneS 4 is 1,4,7,10-tetrathiacyclododecane, and X is Cl − or PF 6 − , were studied by electrospray mass spectrometry (ESMS). Thiacrown fragmentation and intact diimine loss are the two major types of gas-phase reactions observed. The diimine losses occur mainly from the ion pairs formed by the inner sphere cations with halogen anions and are more significant for the complexes with flexible cross-bridged diimines. The fragmentations occur predominantly without changes in the oxidation state of the metal centre.
New Journal of Chemistry, 1999
Page 1. Synthesis and structural characterisation of new RuII[12]aneS 4 complexes with polypyridy... more Page 1. Synthesis and structural characterisation of new RuII[12]aneS 4 complexes with polypyridylic and related ligands Teresa M. Santos,a Brian J. Goodfellow,a Joa8o Madureira,a Ju lio Pedrosa de Jesus,a Vitor Fe lix*a and Michael GB Drewb ...
Polyhedron, 2003
The ruthenium(II) complex [Ru ([14]aneS 4 )(bpym)](BF 4 ) 2 ([14]aneS 4 0/1,4,8,11-tetrathiacyclo... more The ruthenium(II) complex [Ru ([14]aneS 4 )(bpym)](BF 4 ) 2 ([14]aneS 4 0/1,4,8,11-tetrathiacyclotetradecane, bpym 0/2,2?-bipyrimidine) has been prepared by substitution of the labile acetonitrile ligands in the complex [Ru ([14]aneS 4 )(CH 3 CN) 2 ](BF 4 ) 2 by bpym. Both the precursor acetonitrile complex and the polypyridyl complex were characterised by Ru K -edge EXAFS spectroscopy. In addition, the crystal structures of [Ru ([14]aneS 4 )(bpym)](X) 2 (X 0/BF 4 , PF 6 ) were determined by X-ray diffraction.
Inorganic Chemistry, 2002
The synthesis and properties of 3 new ligand-bridged bimetallic complexes, 1(2+), 2(2+), and 3(2+... more The synthesis and properties of 3 new ligand-bridged bimetallic complexes, 1(2+), 2(2+), and 3(2+), containing [RuCl([9]aneS(3))](+) metal centers are reported. Each complex was bridged by a different ditopic ligand. 1(2+) is bridged by 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz), while 2(2+) and 3(2+) are bridged by 2,3-bis(2-pyridyl)pyrazine (dpp) and 2,2'-bipyrimidine (bpym), respectively. The Ru([II]) isovalent states of these complexes have been investigated using a variety of techniques. In the case of 3(2+), X-ray crystallography studies show preferential crystallization of an anti form with respect to coordinated chloride ligands (crystal data for [3][Cl(2)].4H(2)O: C(20)H(38)Cl(4)N(4)O(4)Ru(2)S(6), monoclinic, space group P2(1)/a, a = 10.929(14), b = 13.514(17), c = 11.299(16) A, beta = 90.52(1), V = 1669 A(3), Z = 2). UV/vis spectroscopy shows that spectra of these complexes are dominated by intraligand (pi-->pi) and metal-to-ligand Ru(d)-->L(pi) charge transfer transitions. Electrochemical studies reveal that metal-metal interactions are sufficiently intense to generate the Ru(III)/Ru(II) mixed valence [[RuCl([9]aneS(3))(2)](L-L)](3+) state, where L-L = individual bridging ligands. Although the 1(3+), 2(3+), and 3(3+) mixed valence states were EPR silent at room temperature and 77 K, isotropic solution spectra were observed for the electrochemically generated radical cations 1(+), 2(+), and 3(+), with 1(+) displaying well-resolved hyperfine coupling to bridging ligand nitrogens. Using UV/vis/NIR spectroelectrochemistry, we investigated optical properties of the mixed valence complexes. All three showed intervalence charge transfer (IVCT) bands that are much more intense than electrochemical data indicate. Indeed, a comparison of IVCT data for 1(3+) with an analogous structure containing [(NH3)(3)Ru](2+) metal centers shows that the IVCT in the new complex is an order of magnitude more intense. It is concluded that although the new complexes show relatively weak electrostatic interactions, they possess large resonance energies.
International Journal of Mass Spectrometry, 2008
Ru(II) binuclear complexes with the general formula [(Ru[9]aneS 3 Cl) 2 (L)](PF 6 ) 2 , where L =... more Ru(II) binuclear complexes with the general formula [(Ru[9]aneS 3 Cl) 2 (L)](PF 6 ) 2 , where L = 3,6-bis(2pyridyl)-1,2,4,5-tetrazine (bptz), 2,3-bis(2-pyridyl)pyrazine (dpp), and 2,2 -bipyrimidine (bpym), have been studied by electrospray mass spectrometry (ESI/MS) and electrospray mass spectrometry/mass spectrometry (ESI/MS/MS), in the positive ion mode, to investigate their fragmentation patterns in relation to their structural and spectroscopic properties and also to find out the differences with the gas-phase fragmentations patterns of their mononuclear counterparts.
International Journal of Mass Spectrometry, 2011
Electrospray ionization mass spectrometry (ESIMS) was used to investigate the coordination modes ... more Electrospray ionization mass spectrometry (ESIMS) was used to investigate the coordination modes of the complexes [Ru II ([9]aneS 3 )(HCpz 3 )Cl]Cl, [Ru II ([9]aneS 3 )(HCpz 3 )](Cl)PF 6 and [Ru II ([9]aneS 3 )(HCpz 3 )](PF 6 ) 2 ([9]aneS 3 = 1,4,7-trithiacyclononane; HCpz 3 = tris(1-pyrazolyl)methane) in methanol, acetonitrile and methanol/water solutions. The complex [Ru II ([9]aneS 3 )(HCpz 3 )Cl]Cl shows a rapidly exchangeable Cl ligand, with formation of a doubly charged ion [Ru II ([9]aneS 3 )(HCpz 3 )] 2+ , m/z 248, but the [Ru II ([9]aneS 3 )(HCpz 3 )Cl] + , m/z 531, is also observed and both species still coexist after 16 h. The formation of the [Ru II ([9]aneS 3 )(HCpz 3 )] 2+ and [Ru II ([9]aneS 3 )(HCpz 3 )Cl] + ions by electrospraying solutions of [Ru II ([9]aneS 3 )(dmso)Cl 2 ] (dmso = dimethylsulfoxide) and HCpz 3 in water/methanol was also studied.
Inorganica Chimica Acta, 2003
The synthesis and structural characterisation of the complex [Cr ([14]aneN 4 )(O -dmso)Cl](PF 6 )... more The synthesis and structural characterisation of the complex [Cr ([14]aneN 4 )(O -dmso)Cl](PF 6 ) 2 ×/dmso is reported. The structural studies were carried out in gas-phase by electrospray mass spectrometry (ESMS) and in the solid state by single crystal X-ray diffraction. The metal complex shows a distorted octahedral coordination environment with the macrocycle adopting a folded cis -V conformation. The angle N axial Ã/CrÃ/N axial deviates by only 128 from the ideal value of 1808 for a perfect octahedron indicating that there is a good match between the size of the macrocyclic cavity and the size of Cr(III) ion. The ESMS shows that the complex loses a proton with concomitant opening of the aneN 4 ring to give the [Cr ([14]aneN 4 -H)(dmso)Cl] ' ion with a CH 2 Ä/CHÃ/ pendant chain. This group interacts with dmso leading to the loss of this ligand and to the formation of the [Cr ([14]aneN 4 -H)Cl] ' ion, which has the highest relative abundance (100%). DFT calculations reproduce the geometry of the paramagnetic complex and are consistent with its electronic spectrum. #
Journal of The Chemical Society-dalton Transactions, 2001
J. Chem. Soc., Dalton Trans., 2001, 1628-1633 DOI:10.1039/B101152I (Paper). Synthesis and charact... more J. Chem. Soc., Dalton Trans., 2001, 1628-1633 DOI:10.1039/B101152I (Paper). Synthesis and characterisation of a Ru II ([14]aneS 4 ) complex immobilised in MCM-41-type mesoporous silica. Martyn Pillingera, Isabel S. Gonçalves ...
Metal-based Drugs, 2001
The complexes [Ru ([9]aneS3)(dppz)Cl]Cl 1 and [Ru(II2]aneS4)(dppz)]Ci_ 2 ([9]aneS3=l,4,7 trithiac... more The complexes [Ru ([9]aneS3)(dppz)Cl]Cl 1 and [Ru(II2]aneS4)(dppz)]Ci_ 2 ([9]aneS3=l,4,7 trithiaciclononane and [12]aneS4=l,4,7,10-tetrathiaciclododecane) were synthesised and fully characterised. These complexes belong to a small family of dipyridophenazine complexes with non-polypyridyl ancillary ligands. Interaction studies of these complexes with CT-DNA (UV/Vis titrations, steady-state emission and thermal denaturation) revealed their high affinity for DNA. Intercalation constants determined by UV/Vis titrations are of the same order of magnitude (106) as other dppz metallointercalators, namely [Ru(II)(bpy)2dppz]2+. Differences between and 2 were identified by steady-state emission and thermal denaturation studies. Emission results are in accordance with structural data, which indicate how geometric distortions and different donor and/or acceptor ligand abilities affect luminescence. The possibility of noncovalent interactions between ancillary ligands and nucleobases by van der Waals contacts and H-bridges is discussed. Furthermore, complex undergoes aquation under intra-cellular conditions and an equilibrium with the aquated form I' is attained. This behaviour may increase the diversity of available interaction modes.
Journal of The Chemical Society-dalton Transactions, 2000
A large number of new [Ru II ([9]aneS 3 )(L)Cl] + complexes (where L is a polypyridyl bidentate l... more A large number of new [Ru II ([9]aneS 3 )(L)Cl] + complexes (where L is a polypyridyl bidentate ligand) were synthesized from the precursor [Ru([9]aneS 3 )(dmso)Cl 2 ] in the search for new DNA intercalators. The ancillary ligands used have different molecular architectures ...
International Journal of Mass Spectrometry, 2005
A new series of ruthenium(II) complexes with the general formula [Ru II ([12]aneS 4 )(NN)]X 2 , w... more A new series of ruthenium(II) complexes with the general formula [Ru II ([12]aneS 4 )(NN)]X 2 , where NN are bidentate diimines, [12]aneS 4 is 1,4,7,10-tetrathiacyclododecane, and X is Cl − or PF 6 − , were studied by electrospray mass spectrometry (ESMS). Thiacrown fragmentation and intact diimine loss are the two major types of gas-phase reactions observed. The diimine losses occur mainly from the ion pairs formed by the inner sphere cations with halogen anions and are more significant for the complexes with flexible cross-bridged diimines. The fragmentations occur predominantly without changes in the oxidation state of the metal centre.
New Journal of Chemistry, 1999
Polyhedron, 2003
The ruthenium(II) complex [Ru ([14]aneS 4 )(bpym)](BF 4 ) 2 ([14]aneS 4 0/1,4,8,11-tetrathiacyclo... more The ruthenium(II) complex [Ru ([14]aneS 4 )(bpym)](BF 4 ) 2 ([14]aneS 4 0/1,4,8,11-tetrathiacyclotetradecane, bpym 0/2,2?-bipyrimidine) has been prepared by substitution of the labile acetonitrile ligands in the complex [Ru ([14]aneS 4 )(CH 3 CN) 2 ](BF 4 ) 2 by bpym. Both the precursor acetonitrile complex and the polypyridyl complex were characterised by Ru K -edge EXAFS spectroscopy. In addition, the crystal structures of [Ru ([14]aneS 4 )(bpym)](X) 2 (X 0/BF 4 , PF 6 ) were determined by X-ray diffraction.
Inorganic Chemistry, 2002
The synthesis and properties of 3 new ligand-bridged bimetallic complexes, 1(2+), 2(2+), and 3(2+... more The synthesis and properties of 3 new ligand-bridged bimetallic complexes, 1(2+), 2(2+), and 3(2+), containing [RuCl([9]aneS(3))](+) metal centers are reported. Each complex was bridged by a different ditopic ligand. 1(2+) is bridged by 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz), while 2(2+) and 3(2+) are bridged by 2,3-bis(2-pyridyl)pyrazine (dpp) and 2,2'-bipyrimidine (bpym), respectively. The Ru([II]) isovalent states of these complexes have been investigated using a variety of techniques. In the case of 3(2+), X-ray crystallography studies show preferential crystallization of an anti form with respect to coordinated chloride ligands (crystal data for [3][Cl(2)].4H(2)O: C(20)H(38)Cl(4)N(4)O(4)Ru(2)S(6), monoclinic, space group P2(1)/a, a = 10.929(14), b = 13.514(17), c = 11.299(16) A, beta = 90.52(1), V = 1669 A(3), Z = 2). UV/vis spectroscopy shows that spectra of these complexes are dominated by intraligand (pi-->pi) and metal-to-ligand Ru(d)-->L(pi) charge transfer transitions. Electrochemical studies reveal that metal-metal interactions are sufficiently intense to generate the Ru(III)/Ru(II) mixed valence [[RuCl([9]aneS(3))(2)](L-L)](3+) state, where L-L = individual bridging ligands. Although the 1(3+), 2(3+), and 3(3+) mixed valence states were EPR silent at room temperature and 77 K, isotropic solution spectra were observed for the electrochemically generated radical cations 1(+), 2(+), and 3(+), with 1(+) displaying well-resolved hyperfine coupling to bridging ligand nitrogens. Using UV/vis/NIR spectroelectrochemistry, we investigated optical properties of the mixed valence complexes. All three showed intervalence charge transfer (IVCT) bands that are much more intense than electrochemical data indicate. Indeed, a comparison of IVCT data for 1(3+) with an analogous structure containing [(NH3)(3)Ru](2+) metal centers shows that the IVCT in the new complex is an order of magnitude more intense. It is concluded that although the new complexes show relatively weak electrostatic interactions, they possess large resonance energies.
International Journal of Mass Spectrometry, 2008
Ru(II) binuclear complexes with the general formula [(Ru[9]aneS 3 Cl) 2 (L)](PF 6 ) 2 , where L =... more Ru(II) binuclear complexes with the general formula [(Ru[9]aneS 3 Cl) 2 (L)](PF 6 ) 2 , where L = 3,6-bis(2pyridyl)-1,2,4,5-tetrazine (bptz), 2,3-bis(2-pyridyl)pyrazine (dpp), and 2,2 -bipyrimidine (bpym), have been studied by electrospray mass spectrometry (ESI/MS) and electrospray mass spectrometry/mass spectrometry (ESI/MS/MS), in the positive ion mode, to investigate their fragmentation patterns in relation to their structural and spectroscopic properties and also to find out the differences with the gas-phase fragmentations patterns of their mononuclear counterparts.
International Journal of Mass Spectrometry, 2011
Electrospray ionization mass spectrometry (ESIMS) was used to investigate the coordination modes ... more Electrospray ionization mass spectrometry (ESIMS) was used to investigate the coordination modes of the complexes [Ru II ([9]aneS 3 )(HCpz 3 )Cl]Cl, [Ru II ([9]aneS 3 )(HCpz 3 )](Cl)PF 6 and [Ru II ([9]aneS 3 )(HCpz 3 )](PF 6 ) 2 ([9]aneS 3 = 1,4,7-trithiacyclononane; HCpz 3 = tris(1-pyrazolyl)methane) in methanol, acetonitrile and methanol/water solutions. The complex [Ru II ([9]aneS 3 )(HCpz 3 )Cl]Cl shows a rapidly exchangeable Cl ligand, with formation of a doubly charged ion [Ru II ([9]aneS 3 )(HCpz 3 )] 2+ , m/z 248, but the [Ru II ([9]aneS 3 )(HCpz 3 )Cl] + , m/z 531, is also observed and both species still coexist after 16 h. The formation of the [Ru II ([9]aneS 3 )(HCpz 3 )] 2+ and [Ru II ([9]aneS 3 )(HCpz 3 )Cl] + ions by electrospraying solutions of [Ru II ([9]aneS 3 )(dmso)Cl 2 ] (dmso = dimethylsulfoxide) and HCpz 3 in water/methanol was also studied.
Inorganica Chimica Acta, 2003
The synthesis and structural characterisation of the complex [Cr ([14]aneN 4 )(O -dmso)Cl](PF 6 )... more The synthesis and structural characterisation of the complex [Cr ([14]aneN 4 )(O -dmso)Cl](PF 6 ) 2 ×/dmso is reported. The structural studies were carried out in gas-phase by electrospray mass spectrometry (ESMS) and in the solid state by single crystal X-ray diffraction. The metal complex shows a distorted octahedral coordination environment with the macrocycle adopting a folded cis -V conformation. The angle N axial Ã/CrÃ/N axial deviates by only 128 from the ideal value of 1808 for a perfect octahedron indicating that there is a good match between the size of the macrocyclic cavity and the size of Cr(III) ion. The ESMS shows that the complex loses a proton with concomitant opening of the aneN 4 ring to give the [Cr ([14]aneN 4 -H)(dmso)Cl] ' ion with a CH 2 Ä/CHÃ/ pendant chain. This group interacts with dmso leading to the loss of this ligand and to the formation of the [Cr ([14]aneN 4 -H)Cl] ' ion, which has the highest relative abundance (100%). DFT calculations reproduce the geometry of the paramagnetic complex and are consistent with its electronic spectrum. #
Journal of The Chemical Society-dalton Transactions, 2001
J. Chem. Soc., Dalton Trans., 2001, 1628-1633 DOI:10.1039/B101152I (Paper). Synthesis and charact... more J. Chem. Soc., Dalton Trans., 2001, 1628-1633 DOI:10.1039/B101152I (Paper). Synthesis and characterisation of a Ru II ([14]aneS 4 ) complex immobilised in MCM-41-type mesoporous silica. Martyn Pillingera, Isabel S. Gonçalves ...
Metal-based Drugs, 2001
The complexes [Ru ([9]aneS3)(dppz)Cl]Cl 1 and [Ru(II2]aneS4)(dppz)]Ci_ 2 ([9]aneS3=l,4,7 trithiac... more The complexes [Ru ([9]aneS3)(dppz)Cl]Cl 1 and [Ru(II2]aneS4)(dppz)]Ci_ 2 ([9]aneS3=l,4,7 trithiaciclononane and [12]aneS4=l,4,7,10-tetrathiaciclododecane) were synthesised and fully characterised. These complexes belong to a small family of dipyridophenazine complexes with non-polypyridyl ancillary ligands. Interaction studies of these complexes with CT-DNA (UV/Vis titrations, steady-state emission and thermal denaturation) revealed their high affinity for DNA. Intercalation constants determined by UV/Vis titrations are of the same order of magnitude (106) as other dppz metallointercalators, namely [Ru(II)(bpy)2dppz]2+. Differences between and 2 were identified by steady-state emission and thermal denaturation studies. Emission results are in accordance with structural data, which indicate how geometric distortions and different donor and/or acceptor ligand abilities affect luminescence. The possibility of noncovalent interactions between ancillary ligands and nucleobases by van der Waals contacts and H-bridges is discussed. Furthermore, complex undergoes aquation under intra-cellular conditions and an equilibrium with the aquated form I' is attained. This behaviour may increase the diversity of available interaction modes.
Journal of The Chemical Society-dalton Transactions, 2000
A large number of new [Ru II ([9]aneS 3 )(L)Cl] + complexes (where L is a polypyridyl bidentate l... more A large number of new [Ru II ([9]aneS 3 )(L)Cl] + complexes (where L is a polypyridyl bidentate ligand) were synthesized from the precursor [Ru([9]aneS 3 )(dmso)Cl 2 ] in the search for new DNA intercalators. The ancillary ligands used have different molecular architectures ...
International Journal of Mass Spectrometry, 2005
A new series of ruthenium(II) complexes with the general formula [Ru II ([12]aneS 4 )(NN)]X 2 , w... more A new series of ruthenium(II) complexes with the general formula [Ru II ([12]aneS 4 )(NN)]X 2 , where NN are bidentate diimines, [12]aneS 4 is 1,4,7,10-tetrathiacyclododecane, and X is Cl − or PF 6 − , were studied by electrospray mass spectrometry (ESMS). Thiacrown fragmentation and intact diimine loss are the two major types of gas-phase reactions observed. The diimine losses occur mainly from the ion pairs formed by the inner sphere cations with halogen anions and are more significant for the complexes with flexible cross-bridged diimines. The fragmentations occur predominantly without changes in the oxidation state of the metal centre.
New Journal of Chemistry, 1999
Page 1. Synthesis and structural characterisation of new RuII[12]aneS 4 complexes with polypyridy... more Page 1. Synthesis and structural characterisation of new RuII[12]aneS 4 complexes with polypyridylic and related ligands Teresa M. Santos,a Brian J. Goodfellow,a Joa8o Madureira,a Ju lio Pedrosa de Jesus,a Vitor Fe lix*a and Michael GB Drewb ...
Polyhedron, 2003
The ruthenium(II) complex [Ru ([14]aneS 4 )(bpym)](BF 4 ) 2 ([14]aneS 4 0/1,4,8,11-tetrathiacyclo... more The ruthenium(II) complex [Ru ([14]aneS 4 )(bpym)](BF 4 ) 2 ([14]aneS 4 0/1,4,8,11-tetrathiacyclotetradecane, bpym 0/2,2?-bipyrimidine) has been prepared by substitution of the labile acetonitrile ligands in the complex [Ru ([14]aneS 4 )(CH 3 CN) 2 ](BF 4 ) 2 by bpym. Both the precursor acetonitrile complex and the polypyridyl complex were characterised by Ru K -edge EXAFS spectroscopy. In addition, the crystal structures of [Ru ([14]aneS 4 )(bpym)](X) 2 (X 0/BF 4 , PF 6 ) were determined by X-ray diffraction.
Inorganic Chemistry, 2002
The synthesis and properties of 3 new ligand-bridged bimetallic complexes, 1(2+), 2(2+), and 3(2+... more The synthesis and properties of 3 new ligand-bridged bimetallic complexes, 1(2+), 2(2+), and 3(2+), containing [RuCl([9]aneS(3))](+) metal centers are reported. Each complex was bridged by a different ditopic ligand. 1(2+) is bridged by 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz), while 2(2+) and 3(2+) are bridged by 2,3-bis(2-pyridyl)pyrazine (dpp) and 2,2'-bipyrimidine (bpym), respectively. The Ru([II]) isovalent states of these complexes have been investigated using a variety of techniques. In the case of 3(2+), X-ray crystallography studies show preferential crystallization of an anti form with respect to coordinated chloride ligands (crystal data for [3][Cl(2)].4H(2)O: C(20)H(38)Cl(4)N(4)O(4)Ru(2)S(6), monoclinic, space group P2(1)/a, a = 10.929(14), b = 13.514(17), c = 11.299(16) A, beta = 90.52(1), V = 1669 A(3), Z = 2). UV/vis spectroscopy shows that spectra of these complexes are dominated by intraligand (pi-->pi) and metal-to-ligand Ru(d)-->L(pi) charge transfer transitions. Electrochemical studies reveal that metal-metal interactions are sufficiently intense to generate the Ru(III)/Ru(II) mixed valence [[RuCl([9]aneS(3))(2)](L-L)](3+) state, where L-L = individual bridging ligands. Although the 1(3+), 2(3+), and 3(3+) mixed valence states were EPR silent at room temperature and 77 K, isotropic solution spectra were observed for the electrochemically generated radical cations 1(+), 2(+), and 3(+), with 1(+) displaying well-resolved hyperfine coupling to bridging ligand nitrogens. Using UV/vis/NIR spectroelectrochemistry, we investigated optical properties of the mixed valence complexes. All three showed intervalence charge transfer (IVCT) bands that are much more intense than electrochemical data indicate. Indeed, a comparison of IVCT data for 1(3+) with an analogous structure containing [(NH3)(3)Ru](2+) metal centers shows that the IVCT in the new complex is an order of magnitude more intense. It is concluded that although the new complexes show relatively weak electrostatic interactions, they possess large resonance energies.
International Journal of Mass Spectrometry, 2008
Ru(II) binuclear complexes with the general formula [(Ru[9]aneS 3 Cl) 2 (L)](PF 6 ) 2 , where L =... more Ru(II) binuclear complexes with the general formula [(Ru[9]aneS 3 Cl) 2 (L)](PF 6 ) 2 , where L = 3,6-bis(2pyridyl)-1,2,4,5-tetrazine (bptz), 2,3-bis(2-pyridyl)pyrazine (dpp), and 2,2 -bipyrimidine (bpym), have been studied by electrospray mass spectrometry (ESI/MS) and electrospray mass spectrometry/mass spectrometry (ESI/MS/MS), in the positive ion mode, to investigate their fragmentation patterns in relation to their structural and spectroscopic properties and also to find out the differences with the gas-phase fragmentations patterns of their mononuclear counterparts.
International Journal of Mass Spectrometry, 2011
Electrospray ionization mass spectrometry (ESIMS) was used to investigate the coordination modes ... more Electrospray ionization mass spectrometry (ESIMS) was used to investigate the coordination modes of the complexes [Ru II ([9]aneS 3 )(HCpz 3 )Cl]Cl, [Ru II ([9]aneS 3 )(HCpz 3 )](Cl)PF 6 and [Ru II ([9]aneS 3 )(HCpz 3 )](PF 6 ) 2 ([9]aneS 3 = 1,4,7-trithiacyclononane; HCpz 3 = tris(1-pyrazolyl)methane) in methanol, acetonitrile and methanol/water solutions. The complex [Ru II ([9]aneS 3 )(HCpz 3 )Cl]Cl shows a rapidly exchangeable Cl ligand, with formation of a doubly charged ion [Ru II ([9]aneS 3 )(HCpz 3 )] 2+ , m/z 248, but the [Ru II ([9]aneS 3 )(HCpz 3 )Cl] + , m/z 531, is also observed and both species still coexist after 16 h. The formation of the [Ru II ([9]aneS 3 )(HCpz 3 )] 2+ and [Ru II ([9]aneS 3 )(HCpz 3 )Cl] + ions by electrospraying solutions of [Ru II ([9]aneS 3 )(dmso)Cl 2 ] (dmso = dimethylsulfoxide) and HCpz 3 in water/methanol was also studied.
Inorganica Chimica Acta, 2003
The synthesis and structural characterisation of the complex [Cr ([14]aneN 4 )(O -dmso)Cl](PF 6 )... more The synthesis and structural characterisation of the complex [Cr ([14]aneN 4 )(O -dmso)Cl](PF 6 ) 2 ×/dmso is reported. The structural studies were carried out in gas-phase by electrospray mass spectrometry (ESMS) and in the solid state by single crystal X-ray diffraction. The metal complex shows a distorted octahedral coordination environment with the macrocycle adopting a folded cis -V conformation. The angle N axial Ã/CrÃ/N axial deviates by only 128 from the ideal value of 1808 for a perfect octahedron indicating that there is a good match between the size of the macrocyclic cavity and the size of Cr(III) ion. The ESMS shows that the complex loses a proton with concomitant opening of the aneN 4 ring to give the [Cr ([14]aneN 4 -H)(dmso)Cl] ' ion with a CH 2 Ä/CHÃ/ pendant chain. This group interacts with dmso leading to the loss of this ligand and to the formation of the [Cr ([14]aneN 4 -H)Cl] ' ion, which has the highest relative abundance (100%). DFT calculations reproduce the geometry of the paramagnetic complex and are consistent with its electronic spectrum. #
Journal of The Chemical Society-dalton Transactions, 2001
J. Chem. Soc., Dalton Trans., 2001, 1628-1633 DOI:10.1039/B101152I (Paper). Synthesis and charact... more J. Chem. Soc., Dalton Trans., 2001, 1628-1633 DOI:10.1039/B101152I (Paper). Synthesis and characterisation of a Ru II ([14]aneS 4 ) complex immobilised in MCM-41-type mesoporous silica. Martyn Pillingera, Isabel S. Gonçalves ...
Metal-based Drugs, 2001
The complexes [Ru ([9]aneS3)(dppz)Cl]Cl 1 and [Ru(II2]aneS4)(dppz)]Ci_ 2 ([9]aneS3=l,4,7 trithiac... more The complexes [Ru ([9]aneS3)(dppz)Cl]Cl 1 and [Ru(II2]aneS4)(dppz)]Ci_ 2 ([9]aneS3=l,4,7 trithiaciclononane and [12]aneS4=l,4,7,10-tetrathiaciclododecane) were synthesised and fully characterised. These complexes belong to a small family of dipyridophenazine complexes with non-polypyridyl ancillary ligands. Interaction studies of these complexes with CT-DNA (UV/Vis titrations, steady-state emission and thermal denaturation) revealed their high affinity for DNA. Intercalation constants determined by UV/Vis titrations are of the same order of magnitude (106) as other dppz metallointercalators, namely [Ru(II)(bpy)2dppz]2+. Differences between and 2 were identified by steady-state emission and thermal denaturation studies. Emission results are in accordance with structural data, which indicate how geometric distortions and different donor and/or acceptor ligand abilities affect luminescence. The possibility of noncovalent interactions between ancillary ligands and nucleobases by van der Waals contacts and H-bridges is discussed. Furthermore, complex undergoes aquation under intra-cellular conditions and an equilibrium with the aquated form I' is attained. This behaviour may increase the diversity of available interaction modes.
Journal of The Chemical Society-dalton Transactions, 2000
A large number of new [Ru II ([9]aneS 3 )(L)Cl] + complexes (where L is a polypyridyl bidentate l... more A large number of new [Ru II ([9]aneS 3 )(L)Cl] + complexes (where L is a polypyridyl bidentate ligand) were synthesized from the precursor [Ru([9]aneS 3 )(dmso)Cl 2 ] in the search for new DNA intercalators. The ancillary ligands used have different molecular architectures ...
International Journal of Mass Spectrometry, 2005
A new series of ruthenium(II) complexes with the general formula [Ru II ([12]aneS 4 )(NN)]X 2 , w... more A new series of ruthenium(II) complexes with the general formula [Ru II ([12]aneS 4 )(NN)]X 2 , where NN are bidentate diimines, [12]aneS 4 is 1,4,7,10-tetrathiacyclododecane, and X is Cl − or PF 6 − , were studied by electrospray mass spectrometry (ESMS). Thiacrown fragmentation and intact diimine loss are the two major types of gas-phase reactions observed. The diimine losses occur mainly from the ion pairs formed by the inner sphere cations with halogen anions and are more significant for the complexes with flexible cross-bridged diimines. The fragmentations occur predominantly without changes in the oxidation state of the metal centre.
New Journal of Chemistry, 1999
Polyhedron, 2003
The ruthenium(II) complex [Ru ([14]aneS 4 )(bpym)](BF 4 ) 2 ([14]aneS 4 0/1,4,8,11-tetrathiacyclo... more The ruthenium(II) complex [Ru ([14]aneS 4 )(bpym)](BF 4 ) 2 ([14]aneS 4 0/1,4,8,11-tetrathiacyclotetradecane, bpym 0/2,2?-bipyrimidine) has been prepared by substitution of the labile acetonitrile ligands in the complex [Ru ([14]aneS 4 )(CH 3 CN) 2 ](BF 4 ) 2 by bpym. Both the precursor acetonitrile complex and the polypyridyl complex were characterised by Ru K -edge EXAFS spectroscopy. In addition, the crystal structures of [Ru ([14]aneS 4 )(bpym)](X) 2 (X 0/BF 4 , PF 6 ) were determined by X-ray diffraction.
Inorganic Chemistry, 2002
The synthesis and properties of 3 new ligand-bridged bimetallic complexes, 1(2+), 2(2+), and 3(2+... more The synthesis and properties of 3 new ligand-bridged bimetallic complexes, 1(2+), 2(2+), and 3(2+), containing [RuCl([9]aneS(3))](+) metal centers are reported. Each complex was bridged by a different ditopic ligand. 1(2+) is bridged by 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz), while 2(2+) and 3(2+) are bridged by 2,3-bis(2-pyridyl)pyrazine (dpp) and 2,2'-bipyrimidine (bpym), respectively. The Ru([II]) isovalent states of these complexes have been investigated using a variety of techniques. In the case of 3(2+), X-ray crystallography studies show preferential crystallization of an anti form with respect to coordinated chloride ligands (crystal data for [3][Cl(2)].4H(2)O: C(20)H(38)Cl(4)N(4)O(4)Ru(2)S(6), monoclinic, space group P2(1)/a, a = 10.929(14), b = 13.514(17), c = 11.299(16) A, beta = 90.52(1), V = 1669 A(3), Z = 2). UV/vis spectroscopy shows that spectra of these complexes are dominated by intraligand (pi-->pi) and metal-to-ligand Ru(d)-->L(pi) charge transfer transitions. Electrochemical studies reveal that metal-metal interactions are sufficiently intense to generate the Ru(III)/Ru(II) mixed valence [[RuCl([9]aneS(3))(2)](L-L)](3+) state, where L-L = individual bridging ligands. Although the 1(3+), 2(3+), and 3(3+) mixed valence states were EPR silent at room temperature and 77 K, isotropic solution spectra were observed for the electrochemically generated radical cations 1(+), 2(+), and 3(+), with 1(+) displaying well-resolved hyperfine coupling to bridging ligand nitrogens. Using UV/vis/NIR spectroelectrochemistry, we investigated optical properties of the mixed valence complexes. All three showed intervalence charge transfer (IVCT) bands that are much more intense than electrochemical data indicate. Indeed, a comparison of IVCT data for 1(3+) with an analogous structure containing [(NH3)(3)Ru](2+) metal centers shows that the IVCT in the new complex is an order of magnitude more intense. It is concluded that although the new complexes show relatively weak electrostatic interactions, they possess large resonance energies.
International Journal of Mass Spectrometry, 2008
Ru(II) binuclear complexes with the general formula [(Ru[9]aneS 3 Cl) 2 (L)](PF 6 ) 2 , where L =... more Ru(II) binuclear complexes with the general formula [(Ru[9]aneS 3 Cl) 2 (L)](PF 6 ) 2 , where L = 3,6-bis(2pyridyl)-1,2,4,5-tetrazine (bptz), 2,3-bis(2-pyridyl)pyrazine (dpp), and 2,2 -bipyrimidine (bpym), have been studied by electrospray mass spectrometry (ESI/MS) and electrospray mass spectrometry/mass spectrometry (ESI/MS/MS), in the positive ion mode, to investigate their fragmentation patterns in relation to their structural and spectroscopic properties and also to find out the differences with the gas-phase fragmentations patterns of their mononuclear counterparts.