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Abstract A three‐component synthesis methodology is described for the formation of covalent organic frameworks (COFs) containing extended aromatics. Notably, this approach enables synthesis of the building blocks and COF along parallel reaction landscapes, on a similar timeframe. The use of fragmental building block components, namely pyrene dione diboronic acid as aggregation‐inducing COF precursor and the diamineso‐phenylenediamine (Ph), 2,3‐diaminonaphthalene (Naph), or (1R,2R)‐(+)‐1,2‐diphenylethylenediamine (2Ph) as extending functionalization units in conjunction with 2,3,6,7,10,11‐hexahydroxytriphenylene, resulted in the formation of the corresponding pyrene‐fused azaacene, i.e., Aza‐COF series with full conversion of the dione moiety, long‐range order, and high surface area. In addition, the novel three‐component synthesis was successfully applied to produce highly crystalline, oriented thin films of the Aza‐COFs with nanostructured surfaces on various substrates. The Aza‐COFs exhibit light absorption maxima in the blue spectral region, and each Aza‐COF presents a distinct photoluminescence profile. Transient absorption measurements of Aza‐Ph‐ and Aza‐Naph‐COFs suggest ultrafast relaxation dynamics of excited‐states within these COFs. 

Investigating electron transfer behavior under external electric fields in molecular electronics is crucial for understanding the function of each component and for improving molecular design. Notably, the one-electron transfer is inevitable in molecular wires and switches, for which traditional density functional theory (DFT) and long-range corrected self-consistent-charge density functional tight binding (LC-DFTB) meet significant challenges. Inspired by previous studies on constrained configuration interaction schemes, we present restriction-based configuration interaction (RCI) LC-DFTB, a novel extension of LC-DFTB to deliver an accurate description of one-electron transfer under external electric fields. This approach retains the low cost of LC-DFTB while accurately capturing charge-resonance, localization versus delocalization, and field-induced response in large, structurally complex systems. We demonstrate its performance on a benzene assembly and a polyfluorene, showing that RCI-LC-DFTB efficiently describes the effects of molecular conformation and applied bias on electron localization and transfer. Our method thus provides a robust, scalable tool for the design of molecular electronic and organic photovoltaic materials. 

Porous, stacked two-dimensional covalent organic frameworks (2D COFs) bearing semiconducting linkers can support directional charge transfer across adjacent layers of the COF. To better inform the current and possible future design rules for enhancing electron and hole transport in such materials, an understanding of how linker selection and functionalization affects interlayer electronic couplings is essential. We report electronic structure simulation and analysis of electronic couplings across adjacent linker units and to encapsulated species in functionalized electroactive 2D COFs. The detailed dependence of these electronic couplings on interlayer interactions is examined through scans along key interlayer degrees of freedom and through configurational sampling from equilibrium molecular dynamics on semiempirical potential energy surfaces. Beyond affirming the sensitivity of the electronic coupling to interlayer distance and orientation, these studies offer guidance toward linker functionalization strategies for enhancing charge carrier transport in electroactive 2D COFs.