Intermolecular coupling enhanced thermopower in single- molecule diketopyrrolopyrrole junctions

Sorting out organic molecules with high thermopower is essential for understanding molecular thermoelectrics. The intermolecular coupling offers a unique chance to enhance the thermopower by tuning the bandgap structure of molecular devices, but the investigation of intermolecular coupling in bulk materials remains challenging. Herein, we investigated the thermopower of diketopyrrolopyrrole (DPP) cored single-molecule junctions with different coupling strengths by varying the packing density of the self-assembled monolayers (SAM) using a customized scanning tunneling microscope break junction (STM-BJ) technique. We found that the thermopower of DPP molecules could be enhanced up to one order of magnitude with increasing packing density, suggesting that the thermopower increases with larger neighboring intermolecular interactions. The combined density functional theory (DFT) calculations revealed that the closely-packed configuration brings stronger intermolecular coupling and then reduces the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap, leading to an enhanced thermopower. Our findings offer a new strategy for developing organic thermoelectric devices with high thermopower

Strategic application of CuAAC click chemistry in the modification of natural products for anticancer activity

Natural products play a key role in the history of human drug discovery, and especially for the anticancer agents. Copper(I)-catalyzed alkyne-azide [3+2] cycloaddition (CuAAC) reaction is perhaps the most powerful method for the efficient modification of complex natural products, enabling the direct incorporation of various functional groups accompanied by the formation of the multifunctional 1,2,3-triazole motif, which could not only serve as an basic and hydrophilic connecting group but also as a bioisosteres of 5- or 6-membered heterocycles or an amide group, thus facilitating the improvement of anticancer activities and/or drug-like properties. This contribution extensively summarizes the state-of-the-art application of 1,2,3-triazole in the modification of natural products for anticancer activity. The aim is to gain a deep understanding of the fruitful achievements as well as limitations of CuAAC click chemistry in natural product modification for anticancer activity, and provide perspectives and directions regarding future studies in natural product medicinal chemistry