Photoinduced Charge Transfer at Discrete Molecular Interfaces in Cocrystals.

Precise construction of molecular heterostructures in organic donor-acceptor (D-A) cocrystals is crucial for understanding charge transfer (CT) dynamics and developing high-performance optoelectronic materials. Although cocrystals with densely packed D-A arrays have been widely investigated, discrete heterojunctions at the molecular scale have been scarcely explored. Herein, we demonstrate an approach to create what we have referred to as discrete molecular interfaces in D-A cocrystals employing a tetracationic naphthalenediimide-based macrocycle () and an electron-rich guest pyrene ().

Mechanical-Bond-Enabled Highly Efficient Charge Separation in a Light-Harvesting Hetero[2]Catenane.

Photodriven charge separation is a key process for converting solar energy into chemical energy. However, it remains a challenge to develop artificial light-harvesting materials that can simultaneously achieve ultrafast charge separation and a long-lived charge-separated state with low energy loss. In contrast to conventional strategies based on covalent or noncovalent interactions, we employed a mechanical bond to forcibly assemble two strongly electron-deficient cationic chromophores ( and ), which have very similar reduction potentials and exhibit limited noncovalent interactions, into a hetero[2]catenane ().

Double-Walled Mesoporous Hydrogen-Bonded Organic Frameworks with High Methane Storage Capacity.

The development of mesoporous hydrogen-bonded organic frameworks (HOFs) is critically important for various applications, yet it poses significant challenges. Herein, we present the synthesis and characterization of a robust mesoporous HOF, RP-H200, constructed through the orchestration of π-π stacking and hydrogen bonding interactions in a 2-fold interpenetrated framework. RP-H200 features a unique double-walled structure with a pore size of 3.

Divergent rhodium-catalyzed electrochemical vinylic C-H annulation of acrylamides with alkynes.

α-Pyridones and α-pyrones are ubiquitous structural motifs found in natural products and biologically active small molecules. Here, we report an Rh-catalyzed electrochemical vinylic C-H annulation of acrylamides with alkynes, affording cyclic products in good to excellent yield. Divergent syntheses of α-pyridones and cyclic imidates are accomplished by employing N-phenyl acrylamides and N-tosyl acrylamides as substrates, respectively.

Electrooxidative Iridium-Catalyzed Regioselective Annulation of Benzoic Acids with Internal Alkynes.

Electrochemically driven, Cp*Ir(III)-catalyzed regioselective annulative couplings of benzoic acids with alkynes have been established herein. The combination of iridium catalyst and electricity not only circumvents the need for stoichiometric amount of chemical oxidant, but also ensures broad reaction compatibility with a wide array of sterically and electronically diverse substrates. This electrochemical approach represents a sustainable strategy as an ideal alternative and supplement to the oxidative annulations methodology to be engaged in the synthesis of isocoumarin derivatives.

Site-Selective C-H Functionalization via Synergistic Use of Electrochemistry and Transition Metal Catalysis.

Electrochemical synthesis of organic compounds has emerged as an attractive and environmentally benign alternative to conventional approaches for oxidation and reduction of organic compounds that utilizes electric current instead of chemical oxidants and reductants. As such, many useful transformations have been developed, including the Kolbe reaction, the Simons fluorination process, the Monsanto adiponitrile process, and the Shono oxidation, to name a few. Electrochemical C-H functionalization represents one of the most promising reaction types among many electrochemical transformations, since this process avoids prefunctionalization of substrates and provides novel retrosynthetic disconnections.

Electrochemistry-Enabled Ir-Catalyzed Vinylic C-H Functionalization.

Synergistic use of electrochemistry and organometallic catalysis has emerged as a powerful tool for site-selective C-H functionalization, yet this type of transformation has thus far mainly been limited to arene C-H functionalization. Herein, we report the development of electrochemical vinylic C-H functionalization of acrylic acids with alkynes. In this reaction an iridium catalyst enables C-H/O-H functionalization for alkyne annulation, affording α-pyrones with good to excellent yields in an undivided cell.

Catalytic Asymmetric Cascade Vinylogous Mukaiyama 1,6-Michael/Michael Addition of 2-Silyloxyfurans with Azoalkenes: Direct Approach to Fused Butyrolactones.

An unprecedented cascade vinylogous Mukaiyama 1,6-MA/MA of 2-silyloxyfurans and azoalkenes was realized with a Cu(II)/(t)Bu-Box complex. An array of fused butyrolactones containing multiple stereocenters was generally obtained in good yield (up to 90% yield) with exclusive diastereoselectivity (>20:1 dr) and excellent enantioselectivity (up to 99% ee). Carbon isotope effects measured by (13)C NMR revealed a stepwise mechanism for this annulation process.