A series of regioisomeric Janus-type polyhedral oligomeric silsesquioxanes (POSS) with multiple, mixed surface functional groups has been successfully synthesized based on the cubic T₈-POSS framework in two consecutive thiol–ene reactions. The first thiol–ene addition of β-mercaptoethanol leads to a statistical mixture of multi-adducts where the regioisomers of bis-adducts (ortho, meta, and para isomers) can be isolated at synthetically useful quantities by flash column chromatography. Then, the second thiol–ene reaction readily installs a variety of functional groups onto the remaining vinyl groups of each regioisomer, providing an easy access to precisely defined, hetero-bifunctional Janus POSS nano-building blocks. The configurations and structures of the products have been unambiguously proven by using ¹H, ¹³C, and ²⁹Si NMR spectroscopy as well as MALDI-TOF mass spectrometry.

Spontaneous formation of concentric lamellae was observed in self-assembling giant surfactants consisting of a fluorinated polyhedral oligomeric silsesquioxane (FPOSS) head and flexible polymer tail(s). Owing to the asymmetrical sizes of the head and tail blocks and the rectangular molecular interface, the giant surfactants assumed a truncated-wedge-like molecular shape, which induced morphological curvature during self-assembly, thus resulting in the formation of curved and concentric lamellae. These curved/concentric lamellae were observed in FPOSS-based giant surfactants with different architectures and compositions. The spontaneous curvature formation not only promotes our fundamental understanding of assembly principles, but also provides a promising and efficient approach to the fabrication of a wide range of high-performance devices.

Direct cellular production of topologically complex proteins is of great interest both in supramolecular chemistry and protein engineering. We describe the first cellular synthesis of protein catenanes through the use of the p53 dimerization domain to guide the intertwining of two protein chains and SpyTag–SpyCatcher chemistry for efficient cyclization. The catenane topology was unambiguously proven by SDS-PAGE, SEC, and partial digestion experiments and was shown to confer enhanced stability toward trypsin digestion relative to monomeric control mutants. The assembly–reaction synergy enabled by protein folding and genetically encoded protein chemistry offers a convenient yet powerful approach for creating mechanically interlocked, complex protein topologies in vivo.

Spontaneous formation of concentric lamellae was observed in self-assembling giant surfactants consisting of a fluorinated polyhedral oligomeric silsesquioxane (FPOSS) head and flexible polymer tail(s). Owing to the asymmetrical sizes of the head and tail blocks and the rectangular molecular interface, the giant surfactants assumed a truncated-wedge-like molecular shape, which induced morphological curvature during self-assembly, thus resulting in the formation of curved and concentric lamellae. These curved/concentric lamellae were observed in FPOSS-based giant surfactants with different architectures and compositions. The spontaneous curvature formation not only promotes our fundamental understanding of assembly principles, but also provides a promising and efficient approach to the fabrication of a wide range of high-performance devices.

Direct cellular production of topologically complex proteins is of great interest both in supramolecular chemistry and protein engineering. We describe the first cellular synthesis of protein catenanes through the use of the p53 dimerization domain to guide the intertwining of two protein chains and SpyTag–SpyCatcher chemistry for efficient cyclization. The catenane topology was unambiguously proven by SDS-PAGE, SEC, and partial digestion experiments and was shown to confer enhanced stability toward trypsin digestion relative to monomeric control mutants. The assembly–reaction synergy enabled by protein folding and genetically encoded protein chemistry offers a convenient yet powerful approach for creating mechanically interlocked, complex protein topologies in vivo.

Precise synthesis of nanobuilding blocks with accurately positioned functional groups presents a daunting challenge. Herein, a practical synthesis and thorough characterization of a series of T₈-polyhedral oligomeric silsesquioxane (POSS) di- and triadducts is reported. Upon addition of triflic acid across the double bonds in octavinylPOSS (V₈T₈) followed by hydrolysis, the cubic symmetry of the T₈-POSS cage (O_h) is broken into C_2v (ortho-), C_2v (meta-), and D_3d (para-) for diadducts and further to C_s (oom-), C_s (omp-), and C_3v (mmm-) for triadducts in a stochastic fashion. Their structures and regioconfigurations have been unambiguously demonstrated by ¹H, ¹³C, and ²⁹Si NMR spectroscopy, as well as MALDI-TOF mass spectrometry. The assignment of the diadducts was further corroborated by converting each individual diadduct into triadduct(s), the structure of which is controlled by the symmetry of the precursor. Except for the C_3v triadduct, they can all be prepared in synthetically useful quantities. The presence of two types of highly reactive and mutually orthogonal functional groups facilitates further modification into complex nanostructures and composite materials. These unique regioisomers provide a versatile platform for constructing giant molecules and Janus silsesquioxanes.

Giant surfactants are polymer-tethered molecular nanoparticles (MNPs) and can be considered as a subclass of giant molecules. The MNPs serve as functionalized heads with persistent shape and volume, which may vary in size, symmetry, and surface chemistry. The covalent conjugation of MNPs and polymer tails affords giant surfactants with diverse composition and architecture. Synthetic strategies such as “grafting-from” and “grafting-onto” have been successfully applied to the precise synthesis of giant surfactants, which is further facilitated by the emergence of “click” chemistry reactions. In many aspects, giant surfactants capture the essential features of small-molecule surfactants, yet they have much larger sizes. They bridge the gap between small-molecule surfactants and traditional amphiphilic macromolecules. Their self-assembly behaviors in solution are summarized in this Review. Micelle formation is affected not only by their primary chemical structures, but also by the experimental conditions. This new class of materials is expected to deliver general implications on the design of novel functional materials based on MNP building blocks in the bottom-up fabrication of well-defined nanostructures. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1309–1325

Two molecular Janus particles based on amphiphilic [60]fullerene (C₆₀) derivatives were designed and synthesized by using the regioselective Bingel–Hirsh reaction and the click reaction. These particles contain carboxylic acid functional groups, a hydrophilic fullerene (AC₆₀), and a hydrophobic C₆₀ in different ratios and have distinct molecular architectures: 1:1 (AC₆₀–C₆₀) and 1:2 (AC₆₀–2C₆₀). These molecular Janus particles can self-assemble in solution to form aggregates with various types of micellar morphology. Whereas vesicular morphology was observed for both AC₆₀–C₆₀ and AC₆₀–2C₆₀ in tetrahydrofuran, in a mixture of N,N-dimethylformamide (DMF)/water, spherical micelles and cylindrical micelles were observed for AC₆₀–C₆₀ and AC₆₀–2C₆₀, respectively. A mechanism of formation was tentatively proposed based on the effects of molecular architecture and solvent polarity on self-assembly.