Ultra‐Fast Molecular Rotors within Porous Organic Cages

Abstract

Using variable temperature 2H static NMR spectra and 13C spin‐lattice relaxation times (T1), we show that two different porous organic cages with tubular architectures are ultra‐fast molecular rotors. The central para‐phenylene rings that frame the “windows” to the cage voids display very rapid rotational rates of the order of 1.2–8×106 Hz at 230 K with low activation energy barriers in the 12–18 kJ mol−1 range. These cages act as hosts to iodine guest molecules, which dramatically slows down the rotational rates of the phenylene groups (5–10×104 Hz at 230 K), demonstrating potential use in applications that require molecular capture and release.

Inducing Social Self‐Sorting in Organic Cages To Tune The Shape of The Internal Cavity

“…In parallel, we attempted to address the problem synthetically by targeting the cage stoichiometry of [L + 2B] (+ 6 R,R-CHDA omitted for clarity). Ad euterated variant of aldehyde L3 was available from aprevious study and used in reactions with B1 to allow discrimination of the resultant cages by mass in the UPLC-MS. [79] No such deuterated analogue was available for the mixture of L4 and B2,and the reaction was characterised primarily by 1 HNMR chemical shifts and UPLC retention times.T able 1a nd Table 2 summarise which structures were experimentally observed.…”

A Chiral Bis‐Naphthylated Tetrandrine Dibromide: Synthesis, Self‐Assembly into an Organic Framework Based On Nanosized Spherical Cages, and Inclusion Studies

“…Molecular crystals are usually maintained by stronger intermolecular interactions such as hydrogen bonds or electrostatic forces. [8][9][10][14][15][16][17][18][19][20][21][22][23][34][35][36][37][38] The methanol content in DNT-MeOH ( Figure S6, Supporting Information) was estimated from the number of diffuse electrons determined by the SQUEEZE routine [39] within the solvent accessible voids, after eliminating the contribution of the bromide anions (96 × 36 e). The determined electrons correspond to approx.…”

Luminescence Vapochromism of a Dynamic Copper Iodide Mesocate

“…While 2 H NMR spectroscopy is often use to get information about such molecular rotors, here we could analyze the molecular dynamics of 1 by using solid state 13 C MAS NMR measurements ( T 1 relaxation rate and variable‐temperature (VT) measurements), which did not require laborious deuteration procedure. A significant shorter relaxation time was measured at room temperature for the CH carbon atoms (132.5 ppm) of the phenylene groups of 1 ON ( T 1 <1 s) relative to that of all other carbon atoms which are in the usual range (5–7 s) . Upon cooling the sample, a broadening of the phenyl 13 CH resonance is observed below 246 K (Figure S14), which corresponds to a strong reduction of the phenylene dynamics.…”