Extremely strong tubular stacking of aromatic oligoamide macrocycles

Abstract

Aromatic oligoamide macrocycles 3 undergo extremely strong stacking in both solution and the solid state, forming tubular assemblies that further aggregate.

The intramolecular hydrogen bonded–halogen bond: a new strategy for preorganization and enhanced binding

“…The utility of macrocyclization is unmistakable, yet synthetic challenges have encouraged the development of acyclic molecules that are preorganized by noncovalent interactions ( e.g. hydrogen bonding, 22 – 27 steric effects, 28 , 29 ion-pairing, 30 , 31 and π-π stacking 32 – 34 ). In particular, intramolecular hydrogen bonds (HBs) have been effective at preorganizing structure, including helicies, 35 , 36 cavitands 37 – 39 and ion transporters.…”

“…In particular, intramolecular hydrogen bonds (HBs) have been effective at preorganizing structure, including helicies, 35 , 36 cavitands 37 – 39 and ion transporters. 40 Internal 41 and external 22 , 26 intramolecular HBing are the two predominate strategies used for HB preorganization. 42 Internal intramolecular HBs (proximal to the binding site) usually share the HB donor between the receptor and the guest, which typically weakens the HB interaction to the guest.…”

Stepwise control of host–guest interaction using a coordination polymer gel

“…From the first diffraction peak of Mg-CP ( d 100 = 19.45 Å), the hexagonal lattice parameter a , was estimated as 22.45 Å, which in turn provides the information about the diameter of the columnar stacks in Mg-CP xerogel powder (Fig. 3d ) 34 . The diameter determined from WAXS is in good agreement with the distance of ~24 Å, reported for Zn 2+ -osalazine-based MOF [ Zn 2 (Olz) ] (Fig.…”

“…5a ). The nature of the ICD spectrum is decided by a set of rules proposed by Harata and Kodaka initially for CD inclusion complexes and generalized later for chiral macrocycles 34 . These rules state that (i) any electronic transition that is polarized parallel or perpendicular to the axis of the macrocyclic host gives a positive and negative ICD signal, respectively; (ii) on movement of the chromophore from inside of the macrocycle cavity to outside, keeping the direction of the electronic transition moment unaltered, the sign of ICD is reversed; (iii) when a chromophore remains outside, just near the narrow rim of the CD, the intensity of the ICD signal is greater when compared to being positioned just outside of the wider rim; and (iv) the intensity of an ICD signal due to an electronic transition polarized perpendicular to the macrocycle axis is −1/2 of that when the transition is polarized in the parallel direction and the sign of the ICD signal changes at 54.7°.…”

Columnar Liquid Crystalline Self‐Assembly of Hydrogen‐Bonded Rod–Coil Diblock Complexes Created from Pyrazole/Benzoic acid Derivatives

“…The formation of a lamellar phase from complex 1 , with a low f coil/rod (0.64), indicates that the alkyl chains are too short to surround the aromatic cores; instead, aromatic tetramers are stacked in parallel, and then the aliphatic chains are interdigitated to yield infinite layers. For complexes 2–4 , with higher f coil/rod (0.91 for 2 , 0.96 for 3 , and 1.37 for 4 ), the columnar phases allow more space for the bulky chains, reducing the repulsive force between aliphatic chains, and enabling adoption of less strained aromatic packing …”