Synthesis of Phenylene Vinylene Macrocycles through Acyclic Diene Metathesis Macrocyclization and Their Aggregation Behavior

Abstract

A series of phenylene vinylene macrocycles (PVMs) bearing substituents with various sizes and electronic properties have been synthesized through a one-step acyclic diene metathesis macrocyclization approach and their aggregation behaviors have been investigated. In great contrast to the aggregation of the analogous phenylene ethynylene macrocycles, which aggregate only when substituted with electron-withdrawing groups, these PVMs undergo exceptionally strong aggregation, regardless of the electron-donating or -withdrawing characters of the substituents. The unusual aggregation behavior of the PVMs is further investigated with thermodynamic and computer modeling studies, which show a good agreement with the recently proposed direct through-space interaction model, rather than the polar/π model. The high aggregation tendency of PVMs suggests the great potential of this novel class of shape-persistent macrocycles in a variety of applications, such as ion channels, host-guest recognition, and catalysis.

Surface‐Confined Dynamic Covalent System Driven by Olefin Metathesis

“…This finding is also in contrast to M1 metathesis, in which linear oligomers of M1 were observed in fully stretched conformation with their backbones lying parallel to the surface. Such an observation is in line with the previous report, which shows that ester‐substituted AVM2 has a strong self‐aggregation tendency, whereas nonpolar alkyl‐substituted AVM1 does almost not aggregate under the same conditions . When the temperature was raised to 150 °C, only a trace amount of AVM2 (embedded in the coiled features) was observed (Figure d); this result is also in contrast to that of the olefin metathesis of M1 , which provides a considerable amount of AVM1 at the same temperature.…”

“…As the reaction temperature increased to 60 °C, trimers grew to longer oligomers and AVM2 started to form (≈22 %; Table , Figure S9). Further increasing of the reaction temperature to 100 °C resulted in a surprisingly high abundance of AVM2 (≈65 %; Table , Figure e, and S10) . At 150 °C, the yield of AVM2 was significantly decreased and coiled oligomers were formed as major products (Table , Figure f, and S11), presumably owing to the same reasons (solvent evaporation, catalyst lifetime, and equilibration time) as described in the case of AVM1 .…”

“…Interestingly,atthis temperature,wealso observed the emergence of anew disordered phase (Phase B, Figure 2c)composed of coiled bright features,w hich were assigned to the folded linear oligomers.T his finding is also in contrast to M1 metathesis,inwhich linear oligomers of M1 were observed in fully stretched conformation with their backbones lying parallel to the surface.S uch an observation is in line with the previous report, which shows that ester-substituted AV M2 has as trong self-aggregation tendency, whereas nonpolar alkyl-substituted AV M1 does almost not aggregate under the same conditions. [29] When the temperature was raised to 150 8 8C, only atrace amount of AV M2 (embedded in the coiled features) was observed ( Figure 2d); this result is also in contrast to that of the olefin metathesis of M1,which provides ac onsiderable amount of AV M1 at the same temperature. Although it is possible that AV M2 forms self-aggregated stacks similar to the folding conformation of long linear oligomers,w ed id not observe any such stacked macrocycles on the HOPG surface.A ll of these results clearly show that the substituent effect significantly alters the constitution of the surface-confined dynamic covalent system.…”

“…Further increasing of the reaction temperature to 100 8 8Cresulted in asurprisingly high abundance of AV M2 ( % 65 %; Table 2, Figure 3e,and S10). [29] At 150 8 8C, the yield of AV M2 was significantly decreased and coiled oligomers were formed as major products (Table 2, Figure 3f,and S11), presumably owing to the same reasons (solvent evaporation, catalyst lifetime,a nd equilibration time) as described in the case of AV M1.Itisinteresting to note that atrace amount of arare large macrocycle (14-mer), which has not been directly observed so far,was also detected (indicated by ared arrow in Figure 3e). These results clearly show that surface confinement is indeed capable of modulating the product distribution of ad ynamic system.…”

Self‐Assembly of Clicked Star‐Shaped Triazines into Functional Nanostructures

“…It is well known that π‐stacking causes the upfield shifting of the NMR signals due to the mutual shielding of the aromatic rings . Accordingly, a concentration‐dependent 1 H‐NMR study in chloroform was carried out as a first step to explore this possibility.…”