Dataset Information

Nanoscale ?-? stacked molecules are bound by collective charge fluctuations.

ABSTRACT: Non-covalent ?-? interactions are central to chemical and biological processes, yet the full understanding of their origin that would unite the simplicity of empirical approaches with the accuracy of quantum calculations is still missing. Here we employ a quantum-mechanical Hamiltonian model for van der Waals interactions, to demonstrate that intermolecular electron correlation in large supramolecular complexes at equilibrium distances is appropriately described by collective charge fluctuations. We visualize these fluctuations and provide connections both to orbital-based approaches to electron correlation, as well as to the simple London pairwise picture. The reported binding energies of ten supramolecular complexes obtained from the quantum-mechanical fluctuation model joined with density functional calculations are within 5% of the reference energies calculated with the diffusion quantum Monte-Carlo method. Our analysis suggests that ?-? stacking in supramolecular complexes can be characterized by strong contributions to the binding energy from delocalized, collective charge fluctuations-in contrast to complexes with other types of bonding.

SUBMITTER: Hermann J

PROVIDER: S-EPMC5309697 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Nanoscale π-π stacked molecules are bound by collective charge fluctuations.

Hermann Jan J Alfè Dario D Tkatchenko Alexandre A

Nature communications 20170207

Non-covalent π-π interactions are central to chemical and biological processes, yet the full understanding of their origin that would unite the simplicity of empirical approaches with the accuracy of quantum calculations is still missing. Here we employ a quantum-mechanical Hamiltonian model for van der Waals interactions, to demonstrate that intermolecular electron correlation in large supramolecular complexes at equilibrium distances is appropriately described by collective charge fluctuations ...[more]

PMID: 28169280

Similar Datasets

Project description:Achieving a molecular-level understanding of how the structures and compositions of metal-organic frameworks (MOFs) influence their charge carrier concentration and charge transport mechanism-the two key parameters of electrical conductivity-is essential for the successful development of electrically conducting MOFs, which have recently emerged as one of the most coveted functional materials due to their diverse potential applications in advanced electronics and energy technologies. Herein, we have constructed four new alkali metal (Na, K, Rb, and Cs) frameworks based on an electron-rich tetrathiafulvalene tetracarboxylate (TTFTC) ligand, which formed continuous π-stacks, albeit with different π-π-stacking and S⋯S distances (d π-π and d S⋯S). These MOFs also contained different amounts of aerobically oxidized TTFTC˙+ radical cations that were quantified by electron spin resonance (ESR) spectroscopy. Density functional theory calculations and diffuse reflectance spectroscopy demonstrated that depending on the π-π-interaction and TTFTC˙+ population, these MOFs enjoyed varying degrees of TTFTC/TTFTC˙+ intervalence charge transfer (IVCT) interactions, which commensurately affected their electronic and optical band gaps and electrical conductivity. Having the shortest d π-π (3.39 Å) and the largest initial TTFTC˙+ population (∼23%), the oxidized Na-MOF 1-ox displayed the narrowest band gap (1.33 eV) and the highest room temperature electrical conductivity (3.6 × 10-5 S cm-1), whereas owing to its longest d π-π (3.68 Å) and a negligible TTFTC˙+ population, neutral Cs-MOF 4 exhibited the widest band gap (2.15 eV) and the lowest electrical conductivity (1.8 × 10-7 S cm-1). The freshly prepared but not optimally oxidized K-MOF 2 and Rb-MOF 3 initially displayed intermediate band gaps and conductivity, however, upon prolonged aerobic oxidation, which raised the TTFTC˙+ population to saturation levels (∼25 and 10%, respectively), the resulting 2-ox and 3-ox displayed much narrower band gaps (∼1.35 eV) and higher electrical conductivity (6.6 × 10-5 and 4.7 × 10-5 S cm-1, respectively). The computational studies indicated that charge movement in these MOFs occurred predominantly through the π-stacked ligands, while the experimental results displayed the combined effects of π-π-interactions, TTFTC˙+ population, and TTFTC/TTFTC˙+ IVCT interaction on their electronic and optical properties, demonstrating that IVCT interactions between the mixed-valent ligands could be exploited as an effective design strategy to develop electrically conducting MOFs.

Dataset Information

Nanoscale ?-? stacked molecules are bound by collective charge fluctuations.

Publications

Nanoscale π-π stacked molecules are bound by collective charge fluctuations.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets