Circular dichroism of square-planar, tetradentate Schiff base chelates of copper(II)

Downing, R.S.; Urbach, Frederick

doi:10.1021/ja01050a009

Cited by 192 publications

(68 citation statements)

References 8 publications

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“…The observed signal has a positive sign in the high-energy region and a negative sign for the low-energy part and corresponds, according to studies by Downing et al, to a D configuration of the metal chelate inside the duplex. [16] The salen complex adopts the same absolute configuration inside the DNA duplex as in the crystal (Figure 3). Concerning the metal-based d-d transition at around l = 570 nm, only a small CD effect is observed (Figure 8).…”

Section: Entrymentioning

confidence: 81%

“…In addition, a new band appears at l = 570 nm, which is typical for the N 2 O 2 -Cu chromophore. [16] A titration of Cu 2 + ions against the DNA duplex [9-L2-a/b+en] is shown in Figure 7b In contrast to our observation that an aqueous solution of the homochiral Cu-salen complex 8 shows no CD signal in the range between l = 300 and 700 nm, the duplex [9-L 2 -a/ b+en+Cu] features a strong CD signal in the range of the absorption of the p!p* transition (Figure 8). The observed signal has a positive sign in the high-energy region and a negative sign for the low-energy part and corresponds, according to studies by Downing et al, to a D configuration of the metal chelate inside the duplex.…”

Section: Entrymentioning

confidence: 99%

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Metal–Salen‐Base‐Pair Complexes Inside DNA: Complexation Overrides Sequence Information

Clever

Söltl

Burks

et al. 2006

Chemistry A European J

109

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Two isomeric salicylic aldehyde nucleobases have been prepared and incorporated into various DNA duplexes. Reaction with ethylenediamine leads to formation of the well-known salen ligand inside the DNA double helix. Addition of transition-metal ions such as Cu(2+), Mn(2+), Ni(2+), Fe(2+), or VO(2+) results in the formation of metal-salen-base-pair complexes, which were studied by using UV and circular dichroism (CD) spectroscopy. HPLC and ESI mass spectrometric measurements reveal an unusually high stability of the DNA-metal system. These metal-salen complexes act as interstrand cross-links and thereby lead to a strong stabilization of the DNA duplexes, as studied by thermal de- and renaturing experiments. Complex formation is strong enough to override sequence information even when the preorganization of the ligand precursors is unfavorable and the DNA duplex is distorted by the metal complexation. Furthermore, melting-point studies show that the salen complex derived from ligand 2 fits better into the DNA duplex, in accordance with results obtained from the crystal structure of the corresponding copper-salen complex 8.

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Section: Entrymentioning

confidence: 81%

Section: Entrymentioning

confidence: 99%

Metal–Salen‐Base‐Pair Complexes Inside DNA: Complexation Overrides Sequence Information

Clever

Söltl

Burks

et al. 2006

Chemistry A European J

109

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show abstract

“…In these spectra, there is an intense band at 240-294 nm which is assigned to a π-π* transition originating in the phenyl ring [30]. The bands in the 325-370 nm range, by analogy with LM, are attributed to a π-π* transition originating in the -CH=N-chromophore.…”

Section: Electronic Spectral Studiesmentioning

confidence: 91%

Green and Efficient Synthesis, Characterization and AntiBacterial Activity of Copper (II) Complexes with Unsymmetrical Bidentate Schiff Base Ligands

Srivastava¹,

Singh²,

Singh³

2014

IOSRJAC

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“…They can be attributed to πǞπ* and nǞπ* transitions originating from the C=N groups or from the benzene rings and to metal-to-ligand charge-transfer transitions (dǞπ*). [50][51][52] For chiral compounds 2, 3, 5, 6 and 8, the CD spectra bring some more information in the high-energy region, by evidencing a transition showing a strong CD signal, centred at 410 nm for 2 and 3 ( Figure 14), at 385 nm for 5 and 6 ( Figure 15) and at 370 nm for 9 (Figure S7). This transition can be attributed to a ligandcentred transition, as can be seen from the CD spectra of the ligands alone where a transition occurs at 415 nm, attributed to a nǞπ* transition ( Figure S5).…”

Section: Uv/vis Spectroscopy and Circular Dichroismmentioning

confidence: 99%

From Salicylaldehyde to Chiral Salen Sulfonates – Syntheses, Structures and Properties of New Transition Metal Complexes Derived from Sulfonato Salen Ligands

et al. 2010

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Coordination complexes derived from chiral and nonchiral sulfonato salen ligands {(SalenSO3)Na2: N,N′‐bis(5‐sulfonatosalicylidene)‐1,2‐diaminoethane disodium salt, [(R,R) and (S,S)‐CySalenSO3]NaK: (R,R) and (S,S)‐N,N′‐bis(5‐sulfonatosalicylidene)‐1,2‐diaminocyclohexane sodium–potassium salt} have been synthesized. The crystal structures of the chiral and nonchiral NiII complexes [Ni(SalenSO3)]Na2 (1) and [Ni((R,R)CySalenSO3)]NaK (2) were solved. The other chiral and nonchiral sulfonato salen complexes, [Cu(SalenSO3)]Na2 (4), [Cu((R,R)CySalenSO3)]NaK (5), [Cu((S,S)CySalenSO3)]NaK (6) and [Zn(SalenSO3)]Na2 (7) got hydrolyzed before suitable crystals could form. Yet, their hydrolysis led to the formation of single crystals of the residues of total or partial hydrolysis: 5‐sulfonatosalicylaldehyde sodium salt (A), N‐(5‐sulfonatosalicylidene)‐1,2‐diaminoethane copper(II) [Cu(SalSO3)] (8) and (R,R)‐N‐(5‐sulfonatosalicylidene)‐1,2‐diaminocyclohexane copper(II) {Cu[(R,R)CySalSO3]} (9). All compounds were studied with IR and UV/Vis spectroscopy; chiral compounds were also investigated by circular dichroism. The magnetic properties of the copper compounds were investigated. Whereas 8 shows intermolecular antiferromagnetic interactions between mononuclear CuII complexes, 7 presents a weak intramolecular ferromagnetic coupling (J = 0.66 cm–1, H = –JŜCu1ŜCu2), which has been rationalized by DFT calculations.

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Circular dichroism of square-planar, tetradentate Schiff base chelates of copper(II)

Cited by 192 publications

References 8 publications

Metal–Salen‐Base‐Pair Complexes Inside DNA: Complexation Overrides Sequence Information

Metal–Salen‐Base‐Pair Complexes Inside DNA: Complexation Overrides Sequence Information

Green and Efficient Synthesis, Characterization and AntiBacterial Activity of Copper (II) Complexes with Unsymmetrical Bidentate Schiff Base Ligands

From Salicylaldehyde to Chiral Salen Sulfonates – Syntheses, Structures and Properties of New Transition Metal Complexes Derived from Sulfonato Salen Ligands

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