Hierarchical Self-Assembly of Poly-Pseudorotaxanes into Artificial Microtubules.

Hierarchical self-assembly of building blocks over multiple length scales is ubiquitous in living organisms. Microtubules are one of the principal cellular components formed by hierarchical self-assembly of nanometer-sized tubulin heterodimers into protofilaments, which then associate to form micron-length-scale, multi-stranded tubes. This peculiar biological process is now mimicked with a fully synthetic molecule, which forms a 1:1 host-guest complex with cucurbit[7]uril as a globular building block, and then polymerizes into linear poly-pseudorotaxanes that associate laterally with each other in a self-shape-complementary manner to form a tubular structure with a length over tens of micrometers.

Superacid-Mediated Functionalization of Hydroxylated Cucurbit[]urils.

Herein we report a facile transformation of hydroxylated cucurbit[]uril (CB[], = 6 and 7) to other functionality-conjugated CB[]s by nucleophilic substitution of the hydroxyl group with a wide range of nitriles and alcohols. The reaction proceeds efficiently via generation of a superelectrophilic carbocation on the CB framework from hydroxylated CB[]s under superacidic conditions. One of the resulting CB[] derivatives with reactive functionality, monocarboxylated CB[7], is efficiently conjugated to an enzyme (horseradish peroxidase, HRP) by amide coupling.

Cucurbit[n]uril-based amphiphiles that self-assemble into functional nanomaterials for therapeutics.

Some host-guest complexes of cucurbit[n]uril (CB[n]) host molecules act as supramolecular amphiphiles (SAs), which hierarchically self-assemble into various nanomaterials such as vesicles, micelles, nanorods, and nanosheets in water. The structures and functions of the nanomaterials can be controlled by supramolecular engineering of the host-guest complexes. In addition, functionalization at the periphery of CB[6] and CB[7] generates CB[n]-based molecular amphiphiles (MAs) that can also self-assemble into vesicles or micelle-like nanoparticles in water.

Triazole-containing isothiazolidine 1,1-dioxide library synthesis: one-pot, multi-component protocols for small molecular probe discovery.

The construction of two libraries of triazole-containing isothiazolidine 1,1-dioxides is reported utilizing either a one-pot click/aza-Michael or click/OACC esterification protocol. One core dihydroisothiazole 1,1-dioxide scaffold was prepared rapidly on multigram scale via ring-closing metathesis (RCM) and was subjected to a one-pot multicomponent click/aza-Michael protocol with an array of amines and azides for the generation of a 180-member triazole-containing isothiazolidine 1,1-dioxide library. Alternatively, three daughter scaffolds were generated via the aza-Michael of three amino alcohols, followed by a one-pot, multicomponent click/esterification protocol utilizing a ring-opening metathesis polymerization (ROMP)-derived coupling reagent, oligomeric alkyl carbodiimide (OACC) to generate a 41-member library of triazole-containing isothiazole 1,1-dioxides.

A formal [4 + 4] complementary ambiphile pairing reaction: a new cyclization pathway for ortho-quinone methides.

A formal, one-pot [4 + 4] cyclization pathway for the generation of eight-membered sultams via in situ generation of an ortho-quinone methide (o-QM) is reported. The pairing of ambiphilic synthons in a complementary fashion is examined whereby o-fluorobenzenesulfonamides are merged with in situ generated o-QM in a formal [4 + 4] cyclization pathway to afford 5,2,1-dibenzooxathiazocine-2,2-dioxide scaffolds under microwave (mW) conditions. The method reported represents the first use of an o-QM in a formal hetero [4 + 4] cyclization.