Determining the Relative Structural Relevance of Halogen and Hydrogen Bonds in Self-Assembled Monolayers

Abstract

Although hydrogen bonds have long been established as a highly effective intermolecular interaction for controlling the formation of self-assembled monolayers, the potential utility of the closely related halogen bonds has only recently emerged. The synergistic use of both halogen and hydrogen bonds provides a unique, multitiered strategy toward controlling the morphology of self-assembled structures. However, the interplay between these two interactions within monolayer systems has been little studied. Here, we have systematically investigated this interplay in self-assembled monolayers formed at the solid–liquid interface, with a specific attention on determining the structural relevance of the two interactions in the formation of 2D supramolecular structures. A single molecule that can simultaneously act as both a halogen and a hydrogen bond donor was paired with molecules that are effective acceptors for both of these interactions. The bimolecular networks that result from these pairings were studied by using scanning tunneling microscopy coupled with density functional theory calculations. Additional measurements on similar networks formed by using structural analogues in which halogen-bonding interactions are no longer possible give significant insight into the structure-determining role of these interactions. We find that in some monolayer systems the halogen bonds serve no significant structure-determining role, and the assembly is dominated by hydrogen bonding; however, in other systems, effective cooperation between the two interactions is observed. This study gives clear insight into the synergistic and competitive balance between halogen and hydrogen bonds in self-assembled monolayers. This information is expected to be of considerable value for the future design of monolayer systems using both halogen and hydrogen bonds.

Construction of a series of Ln-MOF luminescent sensors based on a functional “V” shaped ligand

“…"OvC-NH" groups were used as hydrogen bonding sites, which originated from their advantages in molecular recognitions [31][32][33][34][35][36][37] and supramolecular self-assembly process. [38][39][40][41] Considering further the synthetic simplicity and functionality of the ligand, o-phenylenediamine was selected as the vertex of the "V" shaped ligand.…”

Order versus Disorder in the Cocrystals of m-Halogenopyridines with m-Halogenobenzoic Acids: The Effects of the I···O Halogen Bond

“…For this purpose, the only solid pyridine derivative (IPy) was chosen as the reference substance for the nonprotonated and its hydroiodide salt (IPyHI) as the reference for the protonated 3-halogenopyridine. The respective 15 N signals were found at 317.85 and 208.00 ppm. The 15 N signals of the cocrystals were found to be closely grouped in the 288−293 ppm region, with only slight (but still quite distinct) differences between different structural types: 288.3−288.9 ppm for the ordered BrbzacH−Ipy and ClbzacH−Ipy, 290.8−291.9 ppm for the disordered BrbzacH−Brpy and ClbzacH−Brpy, and 293.04 ppm for the disordered IbzacH−Ipy.…”

“…While the structural disorder does not have any considerable effect on the proton position, there is a considerable difference in the spectra of the ordered and disordered structures, with the signals considerably (2−3 times) broader in the disordered structures. This is visible in both the 13 C and 15 N spectra and is particularly evident in the 13 C spectra, where the signals corresponding to the aromatic carbons of the pyridine and the acid are clearly discernible in the ordered cocrystals, but in the spectra of the disordered cocrystals, they have coalesced into 3−4 broad peaks. This would seem to indicate that there is considerable variability of local environments of the aromatic rings in the disordered structures, implying random orientation of the XbzacH−X'py complexes in the disordered crystal structures.…”

“…Chemical shifts were referenced using adamantane as an external reference for tetramethylsilane (TMS), setting the CH 2 signal to 38.48 ppm. 15 N NMR chemical shifts are reported relative to liquid ammonia (δ N 0.0 ppm). The samples were pressed in 4.0 mm diameter ZrO 2 rotors and sealed with Kel-F caps.…”

Structure-Directing Interplay between Tetrel and Halogen Bonding in Co-Crystal of Lead(II) Diethyldithiocarbamate with Tetraiodoethylene

“…The coexistence and combined effects of two or more types of NCIs are important for the rational design of solid materials. Combinations of hydrogen and halogen bonds [ 49 , 50 , 51 , 52 , 53 , 54 , 55 ], hydrogen and chalcogen bonds [ 56 , 57 ], and halogen and chalcogen bonds [ 25 , 58 ] in one system and their interplay have been verified, while the combined effects of TeB together with any other kind of NCI are, so far, little explored. In particular, several papers [ 59 , 60 , 61 , 62 ] outlined the coexistence of Pb···S(N) TeBs with π-stacking and/or hydrogen bonding in solid crystals.…”