Pattubala A. N. Reddy

Metal-assisted red light-induced efficient DNA cleavage by dipyridoquinoxaline-copper(II) complex.

Complete cleavage of double stranded pUC19 DNA by the complex [Cu(dpq)2(H2O)](ClO4)2 (dpq, dipyridoquinoxaline) has been observed on irradiation at 694 nm from a pulsed ruby laser, assisted by the metal d-band transition as well as the quinoxaline triplet states in the absence of any external additives.

Synthesis, crystal structures and properties of ternary copper(II) complexes having 2,2′-bipyridine and α-amino acid salicylaldiminates as models for the type-2 sites in copper oxidases

Abstract Ternary copper(II) complexes [Cu(salgly)(bpy)]·4H 2 O ( 1 ·4H 2 O), [Cu(salala)(bpy)]·4H 2 O·( 2 ·4H 2 O) and [Cu(salphe)(bpy)] ( 3 ), where salgly, salala and salphe are tridentate Schiff base ligands derived from the condensation of salicylaldehyde with glycine, l -alanine and l -phenylalanine, respectively, and bpy is 2,2′-bipyridine, are prepared and structurally characterized. Crystal structures of the complexes display a distorted square-pyramidal (4+1) coordination geometry in which the ONO-donor Schiff base is bonded to the metal in the basal plane. The chelating bpy ligand displays axial-equatorial mode of bonding. Complexes 1 and 2 show chemically significant hydrogen bonding interactions. In addition, complex 2 exhibits π–π stacking, while complex 3 shows attractive CH(imine)–π (phenyl) non-covalent interactions. The one-electron paramagnetic complexes display axial EPR spectra in DMF-glass at 77 K indicating a {d x 2 − y 2 } 1 ground state. The complexes show a d–d band near 670 nm and a charge transfer band near 440 nm in methanol. The complexes are redox active and exhibit a quasi-reversible Cu(II)–Cu(I) couple in DMF-0.1 M TBAP near −0.8 V versus SCE. The complexes are catalytically active in the oxidation of ascorbic acid by dioxygen. The process which is effective with a mole ratio of ascorbic acid to complex as approximately 30, models the ascorbate oxidation property of the type 2 sites in ascorbate oxidase and dopamine β-hydroxylase. The complexes with a N 3 O 2 coordination environment model the active site structure in amine oxidase and mediate deamination reactions in which benzylamine gets oxidized to benzaldehyde in the presence of hydrogen peroxide.

Synthesis, X-ray structure and catalytic properties of a copper(II) Schiff base complex modeling the activity of the CuB site of dopamine β-hydroxylase

Abstract The copper(II) complex [Cu(salgly)(bpy)]·4H2O (1), where salgly is a tridentate glycinatosalicylaldimine Schiff base ligand, is prepared and structurally characterized. The complex is found to be catalytically active in the oxidation of ascorbic acid by dioxygen and the process is also effective in the presence of benzylamine giving benzaldehyde as a product, thus modeling the activity of the CuB site of dopamine β-hydroxylase.

Supramolecular self assembly of a monomeric copper(II) complex of N-salicylidene-2-methoxyaniline forming three-dimensional closed and open channels

A binary copper(II) complex [CuL2] (1), where HL is the Schiff base N-salicylidene-2-methoxyaniline, was prepared and structurally characterized. The complex which crystallizes in cubic space group Ia-3d with an unit cell dimension of 31.2451(17) , V = 30503(3) Angstrom(3), Z = 48, and refined to R-value of 0.0379 for 1700 data with I > 2sigma(I), shows a distorted four coordinate structure with a CuN2O2 chromophore. The complex self-assembles into a supramolecular architecture by non-covalent C-H...O interactions forming open and closed channels.

Intramolecular nucleophilic activation promoting efficient hydrolytic cleavage of DNA by (aqua)bis(dipyridoquinoxaline)copper(II) complex

The axial aqua bound copper(II) complex [Cu(dpq)2(H2O)](ClO4)2, having a planar NN-donor heterocyclic base dipyridoquinoxaline (dpq) as the DNA minor groove binder, shows efficient hydrolytic cleavage of supercoiled DNA in the dark and in the absence of any external reagents, as evidenced from T4 ligase experiments, with a rate of 5.58 +/- 0.4 h(-1) and a rate enhancement of 1.55 x 10(8).

Structural model for the CuB site of dopamine β-hydroxylase and peptidylglycine α-hydroxylating monooxygenase: crystal structure of a copper(II) complex showing N3OS coordination and axial sulfur ligation

A copper(II) complex [Cu(L)(phen)](ClO4) (HL, NSO-donor Schiff base ligand) with a CuIIN3OS geometry showing axial sulfur ligation is a structural model for the CuB site of DβH and PHM, and the complex is catalytically active in the oxidation of ascorbic acid by dioxygen mediated by a copper(I) species.