Solid-State NMR and Diffraction Studies of a Tunable p-tert-Butylcalix[4]arene·Guest Structure

Abstract

The majority of p-tert-butylcalix [4]arene inclusion compounds are 4-fold symmetric in the solid state, with the guest molecular and the host symmetry axes approximately aligned. In contrast, nitrobenzene (and related guests) induces a permanent symmetry-reducing distortion of the p-tert-butylcalix [4]arene compound and occupies a position in which the guest molecular axis is no longer aligned with that of the host. These compounds have been characterized by single-crystal X-ray diffraction as well as 13 C CP-MAS and 2 H NMR in the solid state. Introduction of propane as a second, minority guest in sufficient quantities induces the alignment of the nitrobenzene molecular axis with the host C 4 symmetry axis. Nitrobenzene-d 5 guest dynamics in the symmetric and asymmetric structures reveal a much stronger host‚guest interaction in the latter. The nature of the asymmetry is due to a cooperative effect rather than any intrinsic property of the individual p-tert-butylcalix [4]arene‚guest units. In general, this work give initial insight into the suitability of the p-tert-butylcalixarene[4]arene framework for crystal engineering and illustrates the close connection between dynamics and lattice symmetry and structure. § NRCC No. 40822.

Pseudopolymorphism of Aliphatic Amine/4‐tert‐Butylcalix[4]arene Inclusion Compounds: Supramolecular Stabilization as a Route to Polar Clusters and Layers

“…[19] In both of these compounds, the included guest molecules induce a distortion of the host lattice away from the usual tetragonal symmetry. Given this, a similar guest-induced reduction in calixarene symmetry is expected for clathrate 1.…”

Organometallic cavitands: Cation–π interactions and anion binding via π-metallation

“…1 [14][15][16][17]. In the solid state the calixarenes exhibit an extensive inclusion chemistry with interesting gas and liquid sorption properties [18][19][20][21][22], although binding to neutral guests in solution by the unmodified hosts is weak. Related to the calixarenes is cyclotriveratrylene (CTV), a rigid, shallow bowl-shaped macrocycle with electronrich aromatic rings that is also well known both as a host in its ଝ Based on a keynote lecture presented at the 37th International Conference on Coordination Chemistry, 13 own right [23,24] and as a component in cavitands and cryptophanes [23,25,26].…”

Intramolecular Host–Guest Dynamics of FeCp(CO)2X (X = I and CH3) and Mo2Cp2(CO)6 Included in β‐ or γ‐Cyclodextrin

“…[17] Moreover, it was shown that the nature and the extent of internal motions are dependent on the interplay between the symmetry and the shape of the host and guest molecules. [18][19][20][21] We previously reported the inclusion of simple binary metal-carbonyl complexes such as Fe(CO) 5 and Cr(CO) 6 in β-and γ-CD cavities and their subsequent dynamics were assessed by using solid-state NMR spectroscopic techniques. [20] Interestingly for the highly symmetric Fe(CO) 5 and Cr(CO) 6 systems, the entire molecule undergoes fast isotropic motion inside the CD.…”