Asymmetric Choreography in Pairs of Orthogonal Rotors

Abstract

An asymmetric mechanism for correlated motion occurring in noninteracting pairs of adjacent orthogonal 1,4-bis(carboxyethynyl)bicyclo[1.1.1]pentane (BCP) rotators 1 in the solid state is unraveled and shown to play an important role in understanding the dynamics in the crystalline rotor, Bu4N+[1–]·H2O. Single crystal X-ray diffraction and calculation of rotor–rotor interaction energies combined with variable-temperature, variable-field 1H spin–lattice relaxation experiments led to the identification and microscopic rationalization of two distinct relaxation processes.

Molecular Rods: Facile Desymmetrization of 1,4‐Diethynylbicyclo[2.2.2]octane

“…Cadiot-Chodkiewicz cross-coupling between 6 and 8 [23] gave hybrid BCP/BCO-based rod 9 in a fair isolated yield (Scheme 4). The reaction mixture also contained symmetric structures 10 [16] and 11, which were separated from 9 using column chromatography.…”

“…They are also essential motifs in systems designed for studying various physical phenomena such as singlet energy or electron, transfer. Efforts to construct regular two‐dimensional and three‐dimensional arrays of rotors frequently rely on the use of bridgehead substituted bicyclo[1.1.1]pentanes (BCP),, , , bicyclo[2.2.2]octanes (BCO),, and triptycenes as key building blocks. A few of the BCO‐based systems already showed ultra‐fast rotation, in the solid state and interesting phenomena such as correlated motion in pairs of neighboring rotators, as well as second harmonic generation responses due to local space‐inversion symmetry breaking in centrosymmetric crystals , …”

“…A few of the BCO-based systems already showed ultrafast rotation [13,14] in the solid state and interesting phenomena such as correlated motion in pairs of neighboring rotators, [17][18][19] as well as second harmonic generation responses due to local space-inversion symmetry breaking in centrosymmetric crystals. [16,17] In this context, there is a clear need to extend the library of already existing symmetrically and asymmetrically substituted 1,4-diethynylbicyclo[2.2.2]octane (1) derivatives. We focus our attention on the preparation of the latter, which are more challenging and less well represented among the known structures.…”

An Insight into Non‐Covalent Interactions on the Bicyclo[1.1.1]pentane Scaffold

“…1,3‐Bisethynyl‐BCP and its derivatives have been reported as non‐covalently linked molecular rods. Furthermore, BCP‐1,3‐biscarboxylic acid‐based MOF systems have also been reported as molecular rotors [10b,c,d] . However, an in‐depth analysis of the effect of bridgehead substitution on NCI for different BCP derivatives is still missing from the literature.…”

Bulk Inclusions of Double Pyridazine Molecular Rotors in Hexagonal Tris(o-phenylene)cyclotriphosphazene

“…Preparation and study of regular two- and three-dimensional (2D and 3D) assemblies of molecular-level devices are attracting considerable attention as documented by many original articles, reviews, and book chapters published in recent years. − In general, 2D arrays of molecular devices are accessible using the Langmuir–Blodgett technique, − self-assembly on suitable (mostly metallic) substrates, − or formation of surface inclusions by host–guest interactions − where anchoring parts of molecular devices are inserted inside pores in the host lattice, while their functional parts protrude outside the surface. The 3D materials are usually made by (co-)crystallization of individual components − or by sorption of guest molecules into a well-organized porous host matrix, such as a MOF − or hexagonal tris­( o -phenylene)­cyclotriphosphazene (TPP, Figure ). , …”