Geometry and binding properties of different multiple‐state glycine–Fe⁺/Fe²⁺ complexes

Abstract

Several biologically relevant glycine-Fe þ /Fe 2þ complexes with three different multiplicities were studied for the first time by using the hybrid three-parameter B3LYP density functional method with different basis sets. Single-point calculations were also carried out at the BHLYP level with a larger basis set to refine and calibrate these energy values. The results show that the most stable glycine-Fe þ isomer is the C 1 -symmetric sextet NO-16, in which Fe þ is interacted with both the amino nitrogen and carbonyl oxygen of the glycine ligand. The ground-state structure of glycine-Fe 2þ is the 5 A 00 state 2O-25, which generates from the interaction of Fe 2þ with the two oxygen terminus of the zwitterionic glycine. The calculations indicate that the binding energies mainly derive from the contributions of electrostatic effects, for both the monovalent and divalent metal cation-chelated glycine complexes. The differences in binding energies between these different multiple-state glycine-Fe þ isomers with same combination modes mainly derive from their different electrostatic and polarized effects, and those between the isomers of different combination modes with the same multiple states mainly stem from their different deformation effects. The differences in the relative stabilities of these glycine-Fe þ isomers with different multiple states mainly come from the fact that the more electrostatic contribution of the lower spin complex cannot compensate for the loss of energy enhancement of its corresponding metal cation relative to that of the higher spin counterpart. The same is true for the glycine-Fe 2þ complexes.

OC091: Spontaneous uterine contractions involving sub endometrial myometrium influence endometrial perfusion and?uterine receptivity

“…The B3LYP method provides similar structural parameters compared with the MP2 method, and the vibrational frequencies and intensities are in excellent agreement with the experimental data while requiring far less disk space 10–16. In addition, previous studies have shown that B3LYP is very well‐suited for ion–ligand complexes 15. 17…”

Extensive Computational Study on Coordination of Transition Metal Cations and Water Molecules to Glutamic Acid

“…4,24,25,29 Because of the presence of a third negatively charged center in the side chain of Glu, the interaction between the metal ion and the side-chain carbonyl group can further stabilize the complexes, leading to the preferred tridentate NOOs coordination for Glu−TMC + .…”

Exploration of the Ca2+ Interaction Modes of the Nifedipine Calcium Channel Antagonist

“…[10][11][12][13][14][15][16] In addition, previous studies have shown that B3LYP is very well-suited for ion-ligand complexes. [15,17] Full geometry optimizations without any symmetry constraints, vibrational frequency analyses, and the corresponding zero-point vibrational energy (ZPVE) analyses were performed at the B3LYP/6-31 + G* level of theory. Furthermore, the relevant energies and other parameters of the optimized isomers and the transition-state structures were determined at the B3LYP/6-311 + G* level with the geometries taken from the B3LYP/6-31 + G* level of theory.…”

“…Second, we computed the electrostatic interaction by a very simple pointcharge model, that is, the energy lowering of the deformed nifedipine in the presence of a positive double charge (+ 2) at the same metal-nifedipine distance. [14,15] As the electrostatic relaxation of nifedipine was allowed, the actual lowering also includes the polarization term. Table 1 shows the deformation and the electrostatic contribution to the binding energy of calcium-ion binding to the isolated nifedipine molecule, and includes the relative energies before and after ZPVE corrections of the nifedipine-Ca 2 + complexes.…”