Improvement in hydrogen binding ability of closo-dicarboranes via functionalization and designing of extended frameworks

Abstract Neutral closo-dicarboboranes are reported to have very low $ H_{2} $ binding ability. Herein, we report an improvement in $ H_{2} $ binding energy (Eb) of $ C_{2} %$ B_{4} %$ H_{6} $ by substituting H atoms with different functional groups like X = F, Cl, Br, and XY = BO, CN and NC via quan...
Ausführliche Beschreibung

Abstract Neutral closo-dicarboboranes are reported to have very low $ H_{2} $ binding ability. Herein, we report an improvement in $ H_{2} $ binding energy (Eb) of $ C_{2} %$ B_{4} %$ H_{6} $ by substituting H atoms with different functional groups like X = F, Cl, Br, and XY = BO, CN and NC via quantum-chemical density functional theory based computations. In going from $ B_{6} %$ H_{6} $2− to $ C_{2} %$ B_{4} %$ H_{6} $, the Eb value is reduced from 14.6 kJ $ mol^{−1} $ to 2.7 kJ $ mol^{−1} $. $ C_{2} %$ B_{4} %$ X_{6} $ and $ C_{2} %$ B_{4} $(XY)6 systems, which can bind a total of eight $ H_{2} $ molecules, with one $ H_{2} $ molecule occupying at each B-B-C face, possess an Eb value per $ H_{2} $ in the range of 4.5 kJ $ mol^{−1} $ for X = F, 3.9 kJ $ mol^{−1} $ for X = Cl, 5.9 kJ $ mol^{−1} $ for X = Br, 6.8 kJ $ mol^{−1} $ for XY = BO, 5.8 kJ $ mol^{−1} $ for XY = CN and 5.2 kJ $ mol^{−1} $ for XY = NC. The improvement in Eb value is found to be the highest in case of $ C_{2} %$ B_{4} $(BO)6, which has the ability to bind 6.6 gravimetric wt% of $ H_{2} $. The situation can be made more favorable by applying an external electric field. Energy decomposition analysis reveals that although the dispersion interaction (ca. 55–65%) has significant role in binding $ H_{2} $ with such types of molecules, contribution from electrostatic and orbital interaction is also considerable. Further, we modeled an extended system by linking $ C_{2} %$ B_{4} $(BO)n through ‘C ≡ C’ units for $ H_{2} $ storage purpose. The energy difference between the highest occupied and the lowest unoccupied molecular orbitals gradually lessens with the increase in molecular length. Therefore, it can be tuned gradually by controlling the chain length, which may further open up their potency in the field of electronics. Graphical abstract$ C_{2} %$ B_{4} %$ X_{6} $ (X = F, Cl, Br) and $ C_{2} %$ B_{4} $(XY)6 (XY = BO, CN, NC) show enhanced $ H_{2} $ binding ability from $ C_{2} %$ B_{4} %$ H_{6} $. Further, 1D, 2D and 3-D frameworks can be built by joining $ C_{2} %$ B_{4} $(BO)n units via ‘C ≡ C’ linkage. Ausführliche Beschreibung

Autor*in:	Pan, Sudip [verfasserIn] Zhao, Lili [verfasserIn] Merino, Gabriel [verfasserIn]

Format:	E-Artikel
Sprache:	Englisch

Erschienen:	2018

Schlagwörter:	Hydrogen storage Binding energy Energy decomposition analysis HOMO-LUMO energy gap

Übergeordnetes Werk:	Enthalten in: Journal of molecular modeling - Berlin : Springer, 1995, 24(2018), 11 vom: 05. Okt.
Übergeordnetes Werk:	volume:24 ; year:2018 ; number:11 ; day:05 ; month:10

Links:	Volltext

DOI / URN:	10.1007/s00894-018-3827-0

Katalog-ID:	SPR00792125X