Weak Intermolecular Interactions in the Crystal Structures of Molecules with Tetrahedral Symmetry:  Diamondoid Nets and Other Motifs

Abstract

Motif-forming characteristics of weak intermolecular interactions (Br‚‚‚‚Br, CtCH‚‚‚‚CtC, and CtCBr‚‚‚‚CtC) were examined in the solid state structures, determined by single-crystal X-ray diffraction, of tetraphenylmethane and 1,3,5,7-tetraphenyladamantane derivatives substituted at the four vertices with bromo, ethynyl, bromoethynyl, and 1,3-diethynyl groups. The crystals of the bromo-and ethynyl-substituted tetraphenylmethane derivatives exhibited triply interwoven diamondoid lattices sustained by weak interactions between bromo and ethynyl groups. It was observed that when bromo-and ethynyl groups are interchanged in these compounds, their solid-state structures did not change significantly. The crystals of tetrakis(4-bromoethynyphenyl)methane, as well as 1,4-and 1,3,5-bromoethynylbenzene, were sustained by rare, T-shaped CtCBr‚‚‚‚CtC contacts, but a comparison between these solid-state structures showed significant differences. All terminal 1,3-diynes were unstable compounds that decomposed rapidly. In general, it was observed that tetrahedral building blocks with a larger tetrahedral core, such as adamantane, formed disordered structures or fragile, highly solvated crystals.

On‐Surface Assembly of Hydrogen‐ and Halogen‐Bonded Supramolecular Graphyne‐Like Networks

“…Chemical Synthesis. Thes ynthesis of 2,4,6-tris(bromoethynyl)-1,3,5-triazine (Br-TET) is described in Yang et al [13] 1,3,5-Tris(bromoethynyl)benzene (Br-TEB) was synthesizedf rom known 1,3,5triethynylbenzene [24] (H-TEB) and 2,4,6-tris[(trimethylsilyl)ethynyl]-1,3,5-triazine [10] through brominationwith N-bromosuccinimide.…”

On‐Surface Assembly of Hydrogen‐ and Halogen‐Bonded Supramolecular Graphyne‐Like Networks

“…The synthesis of 2,4,6‐tris(bromoethynyl)‐1,3,5‐triazine (Br‐TET) is described in Yang et al . 1,3,5‐Tris(bromoethynyl)benzene (Br‐TEB) was synthesized from known 1,3,5‐triethynylbenzene (H‐TEB) and 2,4,6‐tris[(trimethylsilyl)ethynyl]‐1,3,5‐triazine through bromination with N‐bromosuccinimide.…”

Light‐Responsive (Supra)Molecular Architectures: Recent Advances

“…We investigated three different compounds ( 1–3 , Figure a) consisting of four E ‐azobenzene units covalently linked to a central tetrahedral carbon atom, with different end groups in the para position of each azobenzene moiety (hydrogen for 1 , methyl for 2 , and tert ‐butyl for 3 ). The rationale that guided us in developing a rigid arrangement of azobenzene photochromic units lays behind the consideration that a shape‐persistent tetrahedral architecture of the molecule, combined with the stiffness of the azobenzene “arms” (Figure b), would hinder a tightly packed arrangement in the solid state . The resulting crystal structure could therefore present enough available free volume, that is, porosity, combined with weak intermolecular interactions allowing photoisomerization of the azobenzene units in the solid crystalline state .…”