Why Are Copper(II) Amino Acid Complexes Not Planar in Their Crystal Structures? An ab Initio and Molecular Mechanics Study.

Inorg Chem

Institute for Medical Research and Occupational Health, Ksaverska c. 2, 10001 Zagreb, Croatia, and Department of Theoretical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria.

Published: June 1999

AI Article Synopsis

  • - This paper explores the structures of copper(II) chelates with different amino acids using advanced quantum mechanics methods, finding that a square-planar shape is most stable in a vacuum, but real-world crystal structures show deviations due to steric effects.
  • - The authors developed a new molecular mechanics model for these copper(II) chelates to better understand the influences of these steric factors, optimizing parameters based on both theoretical and experimental data.
  • - The force field created accurately predicts the molecular geometries of various compounds in both vacuum and crystal conditions, showing a close match to experimental measurements, which helps explain the nonplanarity of these complexes.

Article Abstract

This paper presents geometries of copper(II) chelates with L-alanine, L-leucine, and L-N,N-dimethylvaline optimized by the hybrid density functional method B3LYP. According to the molecular quantum mechanics results, a square-planar copper(II) coordination geometry is electronically favored in vacuo. Deviations from the planar configuration observed in the crystal state should be attributed to sterical intramolecular and/or intermolecular effects. This paper proposes a new molecular mechanics model for tetracoordinated copper(II) amino acidates to investigate these effects in detail. The empirical parameter set for the selected potential energy functions was optimized both with respect to the X-ray crystal structures (internal coordinates and unit cell constants) and with respect to the quantum mechanically derived valence angles around copper. To test this newly developed force field (FF), the equilibrium geometries of 10 molecules are predicted in vacuo and in approximate crystalline surrounding. The results were compared with their ab initio and experimental crystal structures, respectively. The unit cell volumes were reproduced in a range from -7.0% to 2.1%. The total root-mean-square deviations between the experimental and FF in crystal internal coordinates were 0.017 Å in the bond lengths, 2.2 degrees in the valence angles, and 3.6 degrees in the torsion angles. The force field is capable of reproducing the changes in the chelate rings' torsion angles caused by the crystal packing forces and successfully explains the nonplanarity of Cu(II) amino acid complexes in their crystal structures.

Download full-text PDF

Source
http://dx.doi.org/10.1021/ic980471aDOI Listing

Publication Analysis

Top Keywords

crystal structures
12
copperii amino
8
amino acid
8
acid complexes
8
molecular mechanics
8
internal coordinates
8
unit cell
8
valence angles
8
force field
8
experimental crystal
8

Similar Publications

Hydrogen evolution reaction (HER) is a key reaction in electrochemical water splitting for hydrogen production leading to the development of potentially sustainable energy technology. Importantly, the catalysts required for HER must be earth-abundant for their large-scale deployment; silicates representing one such class. Herein, we have synthesized a series of transition mono- and bi- metal metasilicates (with SO32- group) using facile wet-chemical method followed by calcination at a higher temperature.

View Article and Find Full Text PDF

When water is confined in a nanochannel, its thermodynamic and kinetic properties change dramatically compared to the macroscale. To investigate these phenomena, we conducted nonequilibrium molecular dynamics simulations on the heat transfer in copper-water nanochannels with lengths ranging from 12 to 20 nm in the absence and presence of an electric field. The results indicate that in the absence of an electric field ( = 12-20 nm), the binding force between water molecules in the 20 nm nanochannel is the weakest, facilitating thermal motion in the liquid phase.

View Article and Find Full Text PDF

Although Pb-based metal halide perovskites (MHPs) have excellent photoelectric characteristics, their toxicity remains a limiting factor for their widespread application. In the paper, a series of CsCuClxBr3-x (x = 1, 2, 3) MHP microcrystals were developed and their hydrogen evolution performance in ethanol and HX (X = Cl, Br) was also studied. Among them, CsCuCl3 microcrystals exhibit high hydrogen evolution performance in both HX and ethanol, attributed to their longest average lifetime and suitable band structure.

View Article and Find Full Text PDF

Nanographenes and polycyclic aromatic hydrocarbons, both finite forms of graphene, are promising organic semiconducting materials because their optoelectronic and magnetic properties can be modulated through precise control of their molecular peripheries. Several atomically precise edge structures have been prepared by bottom-up synthesis; however, no systematic elucidation of these edge topologies at the molecular level has been reported. Herein, we describe rationally designed modular syntheses of isomeric dibenzoixenes with diverse molecular peripheries, including cove, zigzag, bay, fjord, and gulf structured.

View Article and Find Full Text PDF

Pressure-Dependent Electronic Superlattice in the Kagome Superconductor CsV_{3}Sb_{5}.

Phys Rev Lett

December 2024

Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, Kaiserstrasse 12, D-76131 Karlsruhe, Germany.

We present a high-resolution single crystal x-ray diffraction study of kagome superconductor CsV_{3}Sb_{5}, exploring its response to variations in pressure and temperature. We discover that at low temperatures, the structural modulations of the electronic superlattice, commonly associated with charge-density-wave order, undergo a transformation around p∼0.7  GPa from the familiar 2×2 pattern to a long-range-ordered modulation at wave vector q=(0,3/8,1/2).

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!

A PHP Error was encountered

Severity: Notice

Message: fwrite(): Write of 34 bytes failed with errno=28 No space left on device

Filename: drivers/Session_files_driver.php

Line Number: 272

Backtrace:

A PHP Error was encountered

Severity: Warning

Message: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: /var/lib/php/sessions)

Filename: Unknown

Line Number: 0

Backtrace: