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Covalent organic frameworks (COFs) offer remarkable versatility, combining ordered structures, high porosity, and tailorable functionalities in nanoscale reaction spaces. Herein, we report the synthesis of a series of isostructural, photoactive Wurster‐type COFs achieved by manipulating the chemical and electronic nature of the Wurster aromatic amine building blocks. A series of donor‐acceptor‐donor (D‐A‐D) Wurster building block molecules was synthesized by incorporating heteroaromatic acceptors with varying strengths between triphenylamine donor groups. These tailored building blocks were integrated into a 2D COF scaffold, resulting in highly crystalline structures and similar morphologies across all COFs. Remarkably, this structural uniformity was also achieved in the synthesis of homogeneous and oriented thin films. Steady‐state photoluminescence revealed a tunable red‐shift in film emission exceeding 100 nm, demonstrating effective manipulation of their optical properties. Furthermore, photoelectrochemical (PEC) water splitting studies exhibited a doubled current density (8.1 μA cm−2 at 0.2 VRHE) for the COF with the strongest acceptor unit. These findings highlight the potential of Wurster D‐A‐D COFs in photoelectrochemical water splitting devices and pave the way for further exploration of chemical functionality‐reactivity‐property relationships in this promising class of photoactive materials. [ABSTRACT FROM AUTHOR]

A novel cubic mesoporous metal-organic framework (MOF), consisting of hexahydroxy-cata-hexabenzocoronene (c-HBC) and FeIII ions is presented. The highly crystalline and porous MOF features broad optical absorption over the whole visible and near infrared spectral regions. An electrical conductivity of 10-4 S cm-1 was measured on a pressed pellet. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction (NO 3 RR) is a promising method for pollutant removal and ammonia synthesis and involves the transfer of eight electrons and nine protons. As such, the rational design of catalytic interfaces with enhanced mass transfer is crucial for achieving high ammonia yield rates and Faradaic efficiency (FE). In this work, we incorporated a Cu-bipyridine catalytic interface and fabricated crystalline 2D covalent organic framework films with significantly exposed catalytic sites, leading to improved FE and ammonia yield (FE=92.7 %, NH 3 yield rate=14.9 mg ⋅ h -1 cm -2 in 0.5 M nitrate) compared to bulk catalysts and outperforming most reported NO 3 RR electrocatalysts. The film-like morphology enhances mass transfer across the Cu-bipyridine interface, resulting in superior catalytic performance. We confirmed the reaction pathway and mechanism through in situ characterizations and theoretical calculations. The Cu sites act as primary centers for adsorption and activation, while the bipyridine sites facilitate water adsorption and dissociation, supplying sufficient H* and accelerating proton-coupled electron transfer kinetics. This study provides a viable strategy to enhance mass transfer at the catalytic interface through rational morphology control, boosting the intrinsic activity of catalysts in the NO 3 RR process., (© 2024 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Dibenzo[ g , p ]chrysene can be viewed as a constrained propeller-shaped tetraphenylethylene with reduced curvature and has been utilized to construct dual-pore kagome covalent organic frameworks (COFs) with tightly packed two-dimensional (2D) layers owing to its rigid and more planar structural characteristics. Here, we introduce 2D COFs based on the node 4,4',4″,4‴-(dibenzo[ g , p ]chrysene-2,7,10,15-tetraphenyl)tetraamine (DBCTPTA) featuring extended conjugation compared to the dibenzo[ g , p ]chrysene-3,6,11,14-tetraamine (DBCTA) node. We establish two exceptionally crystalline imine-linked 2D COFs with a hexagonal dual-pore kagome structure based on the DBCTPTA core. The newly synthesized thienothiophene (TT) and benzodithiophene (BDT)-based DBCTPTA COFs show a tight stacking behavior between adjacent layers. Furthermore, we obtained an unprecedented, interpenetrated electron-donor/acceptor host-guest system with an electron-donating BDT DBCTPTA COF synthesized in situ with the soluble fullerene derivative [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) serving as molecular acceptor. The BDT DBCTPTA COF@PCBM film shows a much shorter amplitude-averaged PL lifetime of 7 ± 2 ps compared to 30 ± 4 ps of the BDT DBCTPTA COF film, indicating the light-induced charge transfer process. The successful in situ formation of interpenetrated donor-acceptor heterojunctions within 2D COFs offers a promising strategy for establishing D-A heterojunctions in diverse framework materials with open channel systems.

Three new coordination polymers (CPs) constructed from the linker 1,4-di(dithiocarboxylate) (BDDTC 2- )─the sulfur-analog of 1,4-benzenedicarboxylate (BDC 2- )─together with Mn-, Zn-, and Fe-based inorganic SBUs are reported with description of their structural and electronic properties. Single-crystal X-ray diffraction revealed structural diversity ranging from one-dimensional chains in [Mn(BDDTC)(DMF) 2 ] ( 1 ) to two-dimensional (2D) honeycomb sheets observed for [Zn 2 (BDDTC) 3 ][Zn(DMF) 5 (H 2 O)] ( 2 ). Gas adsorption experiments confirmed a 3D porous structure for the mixed-valent material [Fe 2 (BDDTC) 2 (OH)] ( 3 ). 3 contains a 1:1 ratio of Fe 2+/3+ ions, as evidenced by 57 Fe Mössbauer, X-band EPR, and X-ray absorption spectroscopy. Its empirical formula was established by elemental analysis, thermal gravimetric analysis, infrared vibrational spectroscopy, and X-ray absorption spectroscopy in lieu of elusive single-crystal X-ray diffraction data. In contrast to the Mn- and Zn-based compounds 1 and 2 , the Fe 2+/3+ CP 3 showed remarkably high electrical conductivity of 5 × 10 -3 S cm -1 (according to van der Pauw measurements), which is within the range of semiconducting materials. Overall, our study confirms that sulfur derivatives of typical carboxylate linkers (e.g., BDC) are suitable for the construction of electrically conducting CPs, due to acceptedly higher covalency in metal-ligand bonding compared to the electrically insulating carboxylate CPs or metal-organic frameworks. At the same time, the direct comparison between insulating CPs 1 and 2 with CP 3 emphasizes that the electronic structure of the metal is likewise a crucial aspect to construct electrically conductive materials.