l-Tyrosinatonickel(II) Complex: Synthesis and Structural, Spectroscopic, Magnetic, and Biological Properties of 2{[Ni(l-Tyr)₂(bpy)]}·3H₂O·CH₃OH

Abstract

The complex 2{[Ni(L-Tyr)2(bpy)]}·3H2O·CH3OH [1, where L-Tyr = L-tyrosine; bpy = 2,2'-bipyridine (2,2'-bpy)] was obtained in crystalline form and characterized by X-ray and spectroscopic (FT-IR, NIR-vis-UV, and HFEPR) and magnetic methods. The complex crystallized in the hexagonal system with a = b = 12.8116(18) Å, c = 30.035(6) Å, and space group P3221. The six-coordination sphere around the Ni(2+) ion is formed by two N and two O L-tyrosinato atoms and completed by two N atoms of the 2,2'-bpy molecule. Neighboring [Ni(L-Tyr)2(bpy)] units are joined via weak hydrogen bonds, which create a helical polymeric chain. The coordinated atoms form a strongly distorted cis-NiN2N2'O2 octahedral chromophore. The solid-state electronic spectrum of complex 1 was analyzed assuming D2h symmetry, and the observed bands were assigned to (3)B1g → (3)Ag, (3)B1g → (3)B3g, (3)B1g → (3)B2g, (3)B1g → (3)B3g, (3)B1g → (3)B1g, and (3)B1g → (3)B2g transitions for the I and II d-d bands, respectively. The crystal-field parameters found for D2h symmetry are Dq = 1066 cm(-1), Ds = 617 cm(-1), Dt = -93 cm(-1), B22 = 7000 cm(-1), and Racah B = 812 cm(-1). Magnetic studies revealed the occurrence of hydrogen-bonded metal pairs. The spin Hamiltonian parameters D = -3.262 cm(-1) and E = -0.1094 cm(-1), determined from high-field, high-frequency electron paramagnetic resonance spectra, together with a weak antiferromagnetic exchange parameter J = -0.477 cm(-1), allowed us to reproduce the powder magnetic susceptibility and field-dependent magnetization of the complex. The biological activity of 1 has been tested by using the Fusarium solani, Penicillium verrucosum, and Aspergillus flavus fungi strains and Escherichia coli, Pseudomonas fluorescens, Serratia marcescens, and Bacillus subtilis bacterial strains.

Crystal and electronic structures of Ni(II) silanethiolates containing flexible diamine ligands

“…7). Both negative[20] and positive D[18] were found previously from HF EPR of Ni(II) complexes. Positive D and g x , g y > g z are characteristic for Ni 2+ in elongated octahedral coordination[52,53].…”

“…Positive D and g x , g y > g z are characteristic for Ni 2+ in elongated octahedral coordination[52,53]. Both negative[18,20,54] and positive D[16] were found previously from HF EPR of pseudooctahedral Ni(II) complexes. The EPR g values in hexacoordinated Ni 2+ complexes with distorted octahedral environment are related to the 3 A g → 3 B 1g ,3 A g → 3 B 2g and 3 A g → 3 B 3g transition energies (using D 2h labeling, seeFig…”

“…So far, no HFEPR measurements on octahedral Ni(II) thiolates have been reported [15][16][17][18][19][20].…”

Binary and ternary new water soluble copper(II) complexes of l -tyrosine and substituted 1,10-phenanthrolines: Effect of substitution on DNA interactions and cytotoxicities

“…Because of its good coordination properties, L-Tyr and its derivatives can bind various metal ions, forming complexes in solution as well as in the solid state [26][27][28]. Several combinations of coordination modes via amino N and carboxylate O atoms allowed the formation of typical monomers but also dimers [29], polymers [30], and a tetramer [31] that exhibit interesting spectroscopic, thermodynamic, and magnetic properties [32]. Certain amino acid complexes are found to exhibit potent anti-tumour and artificial nuclease activity.…”

Metal complexes of amino acids and peptides

“…A special issue of Coordination Chemistry Review was devoted to this subject in 2012 (Vol. Scheme 5A belongs to the N-terminally truncated Ab (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) peptide, while Scheme 5B describes the binding modes with its pyroglutamate counterpart, Ab(p3-16). Some of these papers provide a general overview on the role of metal ions (especially Cu(II) and Zn(II)) in neurodegeneration.…”