A facile, stereoselective [2 + 2] photoreaction mediated by cucurbit[8]uril

Abstract

The [2 + 2] photoreaction of (E)-diaminostilbene dihydrochloride proceeds with large rate acceleration and high stereoselectivity via formation of a stable 1:2 host-guest complex with curcurbit[8]uril in solution.

Host‐Enhanced π–π Interaction for Water‐Soluble Supramolecular Polymerization

“…In the 2 AnPy-CB [8] complex, opposite alignment of the two singly charged guests is more favourable, though two AnPy molecules with the same direction can not be fully excluded. [44][45][46] For supramolecular polymeriAbstract: Host-enhanced p-p interaction based on anthracene derivatives and cucurbit [8]uril can be used as the driving force for constructing watersoluble supramolecular polymers. For this purpose, two anthracene moieties were encapsulated into one cucurbit [8]uril cavity, forming a ternary complex.…”

“…This idea can also be extended to other host-enhanced noncovalent interactions. Some examples of p-p interaction in hosts like cyclodextrin or cucurbituril have been presented; [44][45][46][47][48][49] most of them were used as media for studying stereoselective photocyclodimerization. In this work we designed and synthesized bifunctional anthracene derivatives and used host-enhanced p-p interactions between guest anthracene molecules to fabricate supramolecular polymers.…”

Templating Photoreactions in Solution

“…For example, 4,4 ′ -diaminostilbene forms 2:1 inclusion compounds in CB [8] hosts when deprotonated. Irradiation of this assembly leads to the exclusive formation ( > 95:5) of the cis photodimer, 25 analogously to what is observed for related E -3 in γ -CD. Irradiation of cinnamates 8a , 8b , and 8d -8i in the presence of CB [8] in water affords mostly the cis HH photodimers, and, also paralleling the cavity size effects of CDs, smaller CB [7] exclusively leads to the isomerization of the exocyclic double bond.…”

Bimolecular Photoreactions in the Crystalline State

“…Kim and coworkers were the fi rst to demonstrate that the cavity of cucurbituril [8] (CB [8]) can accommodate and orient the olefi nic bonds of diamino stilbene hydrochloride to yield syn dimer in high yields (Scheme 6.22 ). 114 The selective formation of syn dimer within the host was proposed to be due to the arrangement of the olefi ns within the cavity that favors syn dimer formation. A few years ago, our group demonstrated the ability of cucurbiturils to dimerize alkenes that are completely photostable in the solid state.…”