Motion in biological organisms often relies on the functional arrangement of anisotropic tissues that linearly expand and contract in response to external signals. However, a general approach that can implement such anisotropic behavior into synthetic soft materials and thereby produce complex motions seen in biological organisms remains a challenge. Here, a bioinspired approach is presented that uses temperature‐responsive linear hydrogel actuators, analogous to biological linear contractile elements, as building blocks to create three‐dimensional (3D) structures with programmed motions. This approach relies on a generalizable 3D printing method for building 3D structures of hydrogels using a fugitive carrier with shear‐thinning properties. This study demonstrates that the metric incompatibility of an orthogonally growing bilayer structure induces a saddle‐like shape change, which can be further exploited to produce various bioinspired motions from bending to twisting. The orthogonally growing bilayer structure undergoes a transition from a stretching‐dominated motion to a bending‐dominated motion during its shape transformation. The modular nature of this approach, together with the flexibility of additive manufacturing, enables the fabrication of multimodular 3D structures with complex motions through the assembly of multiple functional components, which in turn consist of simple linear contractile elements.

A new, highly selective, bond functionalization strategy, achieved via relay of two transition metal catalysts and the use of traceless acetal directing groups, has been employed to provide facile formation of C–Si bonds and concomitant functionalization of a silicon group in a single vessel. Specifically, this approach involves the relay of Ir-catalyzed hydrosilylation of inexpensive and readily available phenyl acetates, exploiting disubstituted silyl synthons to afford silyl acetals and Rh-catalyzed ortho-C–H silylation to provide dioxasilines. A subsequent nucleophilic addition to silicon removes the acetal directing groups and directly provides unmasked phenol products and, thus, useful functional groups at silicon achieved in a single vessel. This traceless acetal directing group strategy for catalytic ortho-C–H silylation of phenols was also successfully applied to preparation of multisubstituted arenes. Remarkably, a new formal α-chloroacetyl directing group has been developed that allows catalytic reductive C–H silylation of sterically hindered phenols. In particular, this new method permits access to highly versatile and nicely differentiated 1,2,3-trisubstituted arenes that are difficult to access by other catalytic routes. In addition, the resulting dioxasilines can serve as chromatographically stable halosilane equivalents, which allow not only removal of acetal directing groups but also introduce useful functional groups leading to silicon-bridged biaryls. We demonstrated that this catalytic C–H bond silylation strategy has powerful synthetic potential by creating direct applications of dioxasilines to other important transformations, examples of which include aryne chemistry, Au-catalyzed direct arylation, sequential orthogonal cross-couplings, and late-stage silylation of phenolic bioactive molecules and BINOL scaffolds.

Because of the importance of hydrogen atom transfer (HAT) in biology and chemistry, there is increased interest in new strategies to perform HAT in a sustainable manner. Here, we describe a sustainable, net redox-neutral HAT process involving hydrosilanes and alkali metal Lewis base catalysts — eliminating the use of transition metal catalysts — and report an associated mechanism concerning Lewis base-catalysed, complexation-induced HAT (LBCI-HAT). The catalytic LBCI-HAT is capable of accessing both branch-specific hydrosilylation and polymerization of vinylarenes in a highly selective fashion, depending on the Lewis base catalyst used. In this process, earth abundant, alkali metal Lewis base catalyst plays a dual role. It first serves as a HAT initiator and subsequently functions as a silyl radical stabilizing group, which is critical to highly selective cross-radical coupling. EPR study identified a potassiated paramagnetic species and multistate density function theory revealed a high HAT character, yet multiconfigurational nature in the transition state of the reaction.

Two-dimensional (2D) growth-induced 3D shaping enables shape-morphing materials for diverse applications. However, quantitative design of 2D growth for arbitrary 3D shapes remains challenging. Here we show a 2D material programming approach for 3D shaping, which prints hydrogel sheets encoded with spatially controlled in-plane growth (contraction) and transforms them to programmed 3D structures. We design 2D growth for target 3D shapes via conformal flattening. We introduce the concept of cone singularities to increase the accessible space of 3D shapes. For active shape selection, we encode shape-guiding modules in growth that direct shape morphing toward target shapes among isometric configurations. Our flexible 2D printing process enables the formation of multimaterial 3D structures. We demonstrate the ability to create 3D structures with a variety of morphologies, including automobiles, batoid fish, and real human face.

Selective modulation of near-infrared (NIR) fluorescence of single-walled carbon nanotubes (SWNTs) is important for their applications as NIR optical sensors and devices. Here, we study the target-molecule-mediated NIR fluorescence modulation of refolded DNA aptamer-functionalized SWNTs, using platelet-derived growth factor (PDGF) and a PDGF-binding aptamer as a model system. The aptamer–SWNT complexes use SWNT as nanoscale NIR optical emitters and DNA aptamers as molecular recognition elements. The binding of target molecules, PDGFs in this study, to PDGF-binding aptamers on the surface of SWNTs induces a conformation change of the aptamers, which modulates the NIR fluorescence of SWNT emitters. This study suggests that PDGF-binding aptamers noncovalently assembled on the SWNT surface can undergo a temperature- and divalent-ion-induced conformational change into a folded structure through multiple stages, which renders aptamer-functionalized SWNTs optically responsive to target molecules. In addition, our experimental and theoretical results show that the aptamers have a nanotube-diameter-dependent affinity for SWNTs. We demonstrate that refolded aptamer-functionalized SWNTs reversibly modulate their NIR fluorescence in response to PDGF at the nanomolar range 0.1–10 nM with apparent dissociation constants of ∼0.71 nM (solution-phase complexes) and ∼3.1 nM (complexes in hydrogels). This study could open new opportunities to design label-free, reversible NIR optical sensors that can detect various target molecules upon availability or selection of their cognate aptamers.

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[Structure: see text] An efficient, flexible, and highly convergent strategy for accessing skipped bis-THF containing Annonaceous acetogenins is demonstrated by the synthesis of each of (+)-gigantecin (1) and its constitutional isomer (+)-14-deoxy-9-oxygigantecin (11). The skeleton of each compound is produced, at will, from the same precursors via a three-component ring-closing/cross-metathesis sequence that differs only in the ordering of the RCM vs CM events. Another notable aspect is the use of in situ epoxide-closing and -opening of iodohydrins with dimethylsulfonium methylide to provide inverted allylic alcohols.

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