The Powder ESR Spectra of Some Bis(amino acidato)copper(II) Complexes

Abstract

Copper(II) complexes with some natural amino acids were prepared, and their powder ESR spectra were measured. The pattern types of the ESR spectra of these Cu(II) complexes with amino acids were classified into four types, and by the pattern type, the cis- or trans-isomer was estimated.

Study of structural and dynamic characteristics of copper(ii) amino acid complexes in solutions by combined EPR and NMR relaxation methods

“…Several research groups have investigated this equilibrium and obtained parameters of EPR spectra for cis and trans isomers. 6,7,[64][65][66][67][68][69][70] However, one question remained unsolved to this date: parameters of which component of the spectrum should correspond to the cis isomer and which one to the trans isomer. In their original work 6 Goodman et al have supposed that the component of the spectrum which has lower nitrogen super hyperfine (shf) splitting should belong to the trans isomer due to ''smaller net electron delocalization onto nitrogen atoms, in accord with the trans effect''.…”

Disorder at the Chiral Cα Center and Room-Temperature Solid-State cis–trans Isomerization; Synthesis and Structural Characterization of Copper(II) Complexes with d-allo,l-Isoleucine

“…Although all complexes of copper and Ile in the literature are described as complexes with either l -Ile or d,l -Ile, it is not clear which diastereomers of d,l -Ile ,,− were used. Hence, we tried to compare our results with those from the literature. , Since no structures were published, we could only compare colors of compounds and IR data.…”

“…44 Anhydrous and aqueous copper (II) complexes with L-N,N-dimethyl-Ile crystallized only as trans isomers. 45,46 IR spectra, 47,48,49 diffuse reflectance spectra, 49,50 and electron spin resonance (ESR) spectra 44,51,52 were reported to characterize the hydrated cis isomers of Cu(L-Ile) 2 48−52 and Cu(D,L-Ile) 2 47,48−51 and anhydrous trans-[Cu(D,L-Ile) 2 ]. 44,47,49 We varied conditions in both the solution-based and mechanochemical syntheses of the copper(II) complex with L-Ile with an aim to obtain a trans isomer.…”

“…In the crystal structure of the copper­(II) complex with d,l -Ile, Martino et al identified trans -[Cu­( l -Ile) 2 ] and trans -[Cu­( d -Ile) 2 ] as the constituents of the asymmetric unit, but the molecular structures were not determined because of positional disorder . Anhydrous and aqueous copper­(II) complexes with l - N,N -dimethyl-Ile crystallized only as trans isomers. , IR spectra, ,, diffuse reflectance spectra, , and electron spin resonance (ESR) spectra ,, were reported to characterize the hydrated cis isomers of Cu­( l -Ile) 2 − and Cu­( d,l -Ile) 2 ,− and anhydrous trans -[Cu­( d,l -Ile) 2 ]. ,, …”

Conformational Analyses of Physiological Binary and Ternary Copper(II) Complexes with l‐Asparagine and l‐Histidine; Study of Tridentate Binding of Copper(II) in Aqueous Solution

“…The solid‐state copper(II)‐ l ‐Asn complexes were characterized by the IR spectra [Cu( l ‐Asn) 2 , Cu( l ‐His)( l ‐Asn)], a Raman spectrum of Cu( l ‐Asn) 2 , the electron paramagnetic resonance (EPR) spectra of Cu( l ‐Asn) 2 , and by the X‐ray single crystal structural analysis . Cu( l ‐Asn) 2 crystallized as an anhydrous trans compound .…”