Hydrogen Bond-Driven Self-Assembly between Single-Layer MoS₂ and Alkyldiamine Molecules

Abstract

We report the synthesis, structure determination, and quantum-chemical analysis of a new family of layered nanocrystals (NCs) obtained by a liquid-phase assembly reaction of exfoliated, negatively charged MoS 2 sheets with alkyldiammonium ions. A combined PXRD, TEM, FTIR and DFT study allowed us to determine the atomic structure of these turbostratically disordered NCs and to reveal the topology of cation-MoS 2 binding interactions. The diamine molecules sandwiched between the sulfur layers of the adjacent 1T-MoS 2 sheets were found to interlink these sheets through the hydrogen bonding interaction network. Quantification of these interactions on the basis of the analysis of calculated electron density distribution showed that the strong NH•••S bonds contribute 40−80% of the total cation-MoS 2 hydrogen bonding interaction energy (33−38 kcal/mol), being accompanied by the contribution of the weaker, but more numerous CH•••S bonds. The short-range ordering in the positions of neighboring MoS 2 layers was identified and its relationship with organic−inorganic hydrogen bonding was established. DFT based comparison of energetic characteristics for the assembled NCs and their delaminated and deprotonated models was performed in order to evaluate stability of NCs against delamination and deprotonation. The data obtained in this study show the prospect for crystal engineering of hydrogen-bonding-based new MoS 2 -organic nanomaterials.

Enhancement of 1T‐MoS2 Superambient Temperature Stability and Hydrogen Evolution Performance by Intercalating a Phenanthroline Monolayer

“…The geometry of the MoS 2 layer was taken to be of the 1T type. Similar geometry was previously found from PXRD data for the compounds with other organic guests [29–31,48] . The initial geometry of the organic layer was constructed assuming strictly parallel disposition of the planar Phen core with respect to the sulfide layers in agreement with the observed interlayer lattice expansion.…”

“…The Phen core kept roughly parallel orientation to the sulfide sheets forming with them an angle of 9°. Notably, the Phen molecule lies almost entirely over the ridges of the nanorelief (Figure 5b and Figure S6), differing in this respect with the previously described alkylamine guests tending to occupy the valleys [31] . Such a disposition of the Phen molecules provides the shortest C−S and N−S distances thus favoring involvement of the aromatic π‐system in the interaction with sulfur (Figure 5c) similarly to the recently reported π‐stacked MoS 2 assembly with another aromatic heterocycle, triazatriangulene [52] .…”

“…Such architecture is realized in the heterolayered MoS 2 ‐organic nanocrystals assembled in liquid media at room temperature from negatively charged MoS 2 monolayers and organic cationic species [26–28] . In this type of hybrid structures, the sulfide layers was proven to adopt the geometry of 1T‐MoS 2 and their S atoms participate in the NH…S, CH…S and π…S interactions with the guest molecules as shown for several compounds by the PXRD pattern modeling and DFT calculations [29–31] . The 1T structure is stabilized in the sulfide layers of these compounds as compared to pure 1T‐MoS 2 phase as evidenced by an increase of the 1T‐2H transition temperature [30,32] .…”

Nanostructured tungsten sulfides: insights into precursor decomposition and the microstructure using X-ray scattering methods

“…[24][25][26][27][28][29][30][31] Refinement of turbostratic disorder in exfoliated and restacked MoS 2 intercalated with organic cations has recently been demonstrated. [32][33][34] Total scatteringalso known as pair distribution function (PDF)has only scarcely been applied to such layered compounds, e.g. to lithiated MoS 2 , 35 restacked WS 2 , 36 Ag x MoS 2 37 or a molybdenum polysulfide chalcogel.…”

Probing Hydrogen-Bonding Properties of a Negatively Charged MoS2 Monolayer by Powder X-ray Diffraction and Density Functional Theory Calculations

“…The problem, however, has recently been overcome with the new combined powder X-ray diffraction (PXRD) and density functional theory (DFT) computation approach, which consists in diffraction pattern modeling of turbostartically disordered solids with the K. Ufer supercell and optimization of the models by quantum-chemical calculations . This approach has already allowed successful estimation of the structure of MoS 2 compounds with quaternary alkyl­(aryl)­ammoniums, naphthylammoniums, and alkylenediammoniums. − The distinctive feature of these compounds is the existence of H-bonding interactions of various strengths between the S atoms of MoS 2 and molecular fragments. Obviously, a similar set of hydrogen bonding interactions can be expected on the surface of MoS 2 because hydrogen bonding typically governs the binding of organic species with the surfaces-containing donor atoms such as O or S.…”