Neutron Scattering of Aromatic and Aliphatic Liquids

Falkowska, Marta; Bowron, Daniel T.; Manyar, Haresh; Hardacre, Christopher; Youngs, Tristan G. A.

doi:10.1002/cphc.201600149

Cited by 45 publications

(100 citation statements)

References 41 publications

(100 reference statements)

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“…This, together with simulation based structure refinement, for example Empirical Potential Structure Refinement (EPSR), 52 allows spatial and orientational correlations in liquids to be studied in unprecedented detail. Our previous neutron scattering study of liquid benzene, 42 later confirmed by Falkowska et al, 50 shows that benzene prefers perpendicular nearest neighbours in a Y-shaped geometry. Parallel displaced geometries are present as a shoulder in the correlation surface, but are not the dominant interaction.…”

Section: 17mentioning

confidence: 51%

“…This should be shown in contrast to benzene, 42,50 where although a parallel arrangement of the molecules is seen as a shoulder in the angular radial distribution function, it is not a local maximum. It also should be noted that perpendicular nearest neighbours are a local maximum in the data, and of a similar height as seen in liquid benzene.…”

Section: Liquid Naphthalene At 85 8cmentioning

confidence: 99%

“…Neutron scattering is an unparalleled technique in the study of the structure of molecular liquids, and has recently been used to study a number of aromatic liquids. 42,[49][50][51] The neutron scattering length is dependent on the isotope. Isotopic substitution, particularly H/D and *N/ 15 N, can therefore be used to provide multiple datasets from the same underlying liquid structure.…”

Section: 17mentioning

confidence: 99%

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The structures of liquid pyridine and naphthalene: the effects of heteroatoms and core size on aromatic interactions

Headen

Cullen

Patel

et al. 2018

Phys. Chem. Chem. Phys.

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Total neutron scattering has been used in conjunction with H/D and *N/ 15 N isotopic substitution to determine the detailed liquid-state structures of pyridine and naphthalene. Analysis of the data via an empirical potential-based structure refinement method has allowed us to interrogate the full six-dimensional spatial and orientational correlation surfaces in these systems, and thereby to deduce the fundamental effects of a heteroatom and aromatic core-size on intermolecular p-p interactions. We find that the presence of a nitrogen heteroatom, and concomitant dipole moment, in pyridine induces surprisingly subtle departures from the structural correlations observed in liquid benzene: in both cases the most probable local motif is based on perpendicular (edge-to-face) intermolecular contacts, while parallel-displaced configurations give rise to a clear shoulder in the correlation surface. However, the effect of the heteroatom is revealed through detailed analysis of the intermolecular orientational correlations. This analysis shows a tendency for neighbouring pyridine molecules to direct one meta-and one para-hydrogen towards the neighbouring aromatic p-orbitals in edge-to-face configurations, while head-to-tail alignment of adjacent nitrogen atoms is favoured in faceto-face configurations. In contrast to this, increasing aromatic core size from one to only two rings has a clear and profound effect on the p-p interactions and liquid structure. Our experiments show that naphthalenenaphthalene contacts are dominated by parallel-displaced configurations, akin to those found in graphite. This marks a fundamental difference with the structure of liquid benzene, in which perpendicular geometries are favoured. Furthermore, it is remarkable to note that in the systems studied, the most favoured spatioorientational configurations observed in the liquid state are not predicted from ab initio calculations and/or solid state crystallographic studies. This highlights the need for caution when extrapolating the results of crystallographic and computational studies to aromatic interactions in liquids and disordered systems.

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Section: 17mentioning

confidence: 51%

Section: Liquid Naphthalene At 85 8cmentioning

confidence: 99%

Section: 17mentioning

confidence: 99%

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The structures of liquid pyridine and naphthalene: the effects of heteroatoms and core size on aromatic interactions

Headen

Cullen

Patel

et al. 2018

Phys. Chem. Chem. Phys.

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“…19,20 Solvation as studied through neutron diffraction is a wide-ranging and active subject with applications in many fields ranging from physical chemistry to biochemistry. [21][22][23][24][25][26][27] In addition to the AB-ammonia interactions, a more fundamental interest in the nature of solvation in such a (di)hydrogen bondrich environment sparks our study of these systems. Insight into the AB-AB intermolecular interactions is a further goal for this work.…”

mentioning

confidence: 99%

Dihydrogen vs. hydrogen bonding in the solvation of ammonia borane by tetrahydrofuran and liquid ammonia

Ingram

Headen

Skipper

et al. 2018

Phys. Chem. Chem. Phys.

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The solvation structures of two systems rich in hydrogen and dihydrogen bonding interactions have been studied in detail experimentally through neutron diffraction with hydrogen/deuterium isotopic substitution. The results were analysed by an atomistic Monte Carlo simulation employing refinement to the experimental scattering data. The systems studied were the hydrogen storage material ammonia borane (NH 3 BH 3 , AB) dissolved in tetrahydrofuran (THF), and liquid ammonia (NH 3 ), the latter in which AB shows unusually high solubility (260 g AB per 100 g NH 3 ) and potential regeneration properties. The full orientational and positional manner in which AB-AB, AB-THF and AB-NH 3 pairs interact with each other were successfully deciphered from the wide Q-range total neutron scattering data. This provided an unprecedented level of detail into such highly (di)hydrogen bonding solute-solvent interactions. In particular this allowed insight into the way in which H-B acts as a hydrogen bond acceptor. The (di)hydrogen bonding was naturally determined to dictate the intermolecular interactions, at times negating the otherwise expected tendency for polar molecules to align themselves with anti-parallel dipole moments. Several causes for the extreme solubility of AB in ammonia were determined, including the ability of ammonia to (di)hydrogen bond to both ends of the AB molecule and the small size of the ammonia molecule relative to AB and THF. The AB B-H to ammonia H dihydrogen bond was found to dominate the intermolecular interactions, occurring almost three times more often than any other hydrogen or dihydrogen bond in the system. The favourability of this interaction was seen on the bulk scale by a large decrease in AB clustering in ammonia compared to in the dihydrogen bond-less THF.

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“…[7,8] MCM-41 is an idealized model catalyst support formed from aporous silica glass,comprising ahexagonally organized lattice of cylindrical pores.F or the system under investigation, features corresponding to the regular ordering of the pore network can be observed via Bragg scattering peaks in the low-Q range (corresponding to correlations at longer real-space distances) of the total structure factor (Figure 1), whilst the diffuse scattering arising from the liquid present in the pores,f rom Figure 1. [17] Figure 1s hows the total structure factor obtained from the EPSR simulation filled with benzene-d 6 compared with experimental data. Dotted line expresses the experimental data while the solid line shows that generated by Empirical Potential Structure Refinement (EPSR) followingconstraint by the experimental data.…”

mentioning

confidence: 99%