The structural diversity of three-dimensional (3D) covalent organic frameworks (COFs) are limited as there are only a few choices of building units with multiple symmetrically distributed connection sites. To date, 4 and 6-connected stereoscopic nodes with T d , D 3h , D 3d and C 3 symmetries have been mostly reported, delivering limited 3D topologies. We propose an efficient approach to expand the 3D COF repertoire by introducing a high-valency quadrangular prism (D 4h ) stereoscopic node with a connectivity of eight, based on which two isoreticular 3D imine-linked COFs can be created. Low-dose electron microscopy allows the direct visualization of their 2-fold interpenetrated bcu networks. These 3D COFs are endowed with unique pore architectures and strong molecular binding sites, and exhibit excellent performance in separating C 2 H 2 /CO 2 and C 2 H 2 /CH 4 gas pairs. The introduction of highvalency stereoscopic nodes would lead to an outburst of new topologies for 3D COFs.

Currently, less favorable C=O hydrogenation and weak concerted acid catalysis cause unsatisfactory catalytic performance in the upgrading of biomass‐derived furfurals (i.e., furfural, 5‐methyl furfural, and 5‐hydroxymethyl furfural) to ketones (i.e., cyclopentanone, 2,5‐hexanedione, and 1‐hydroxyl‐2,5‐hexanedione). A series of partially oxidized MAX phase (i.e., Ti3AlC2, Ti2AlC, Ti3SiC2) supporting Pd catalysts were fabricated, which showed high catalytic activity; Pd/Ti3AlC2 in particular displayed high performance for conversion of furfurals into targeted ketones. Detailed studies of the catalytic mechanism confirm that in situ hydrogen spillover generates Frustrated Lewis H+−H− pairs, which not only act as the hydrogenation sites for selective C=O hydrogenation but also provide acid sites for ring opening. The close intimate hydrogenation and acid sites promote bifunctional catalytic reactions, substantially reducing the reported minimum reaction temperature of various furfurals by at least 30–60 °C.

Two-dimensional (2D) covalent organic frameworks (COFs) possess designable pore architectures but limited framework topologies. Until now, 2D COFs adopting the kgd topology with ordered and rhombic pore geometry have rarely been reported. Here, an isoreticular series of 2D COFs with the kgd topology and controllable pore size is synthesized by employing a C 6-symmetric aldehyde, i.e., hexa­(4-formylphenyl)­benzene (HFPB), and C 3-symmetric amines i.e., tris­(4-aminophenyl)­amine (TAPA), tris­(4-aminophenyl)­trazine (TAPT), and 1,3,5-tris­[4-amino­(1,1-biphenyl-4-yl)]­benzene (TABPB), as building units, referred to as HFPB–TAPA, HFPB–TAPT, and HFPB–TABPB, respectively. The micropore dimension down to 6.7 Å is achieved in HFPB–TAPA, which is among the smallest pore size of reported 2D COFs. Impressively, both the in-plane network and stacking sequence of the 2D COFs can be clearly observed by low-dose electron microscopy. Integrating the unique kgd topology with small rhombic micropores, these 2D COFs are endowed with both short molecular diffusion length and favorable host–guest interaction, exhibiting potential for drug delivery with high loading and good release control of ibuprofen.

Riemann surfaces are deformed versions of the complex plane in mathematics. Locally they look like patches of the complex plane, but globally, the topology may deviate from a plane. Nanostructured graphitic carbon materials resembling a Riemann surface with helicoid topology are predicted to have interesting electronic and photonic properties. However, fabrication of such processable and large π-extended nanographene systems has remained a major challenge. Here, we report a bottom-up synthesis of a metal-free carbon nanosolenoid (CNS) material with a low optical bandgap of 1.97 eV. The synthesis procedure is rapid and possible on the gram scale. The helical molecular structure of CNS can be observed by direct low-dose high-resolution imaging, using integrated differential phase contrast scanning transmission electron microscopy. Magnetic susceptibility measurements show paramagnetism with a high spin density for CNS. Such a π-conjugated CNS allows for the detailed study of its physical properties and may form the base of the development of electronic and spintronic devices containing CNS species.

Recent advances in wearable and implantable electronics have increased the demand for biocompatible integrated energy storage systems. Conducting polymers, such as polyaniline (PANi), have been suggested as promising electrode materials...