Core-substituted naphthalenediimides

This feature article reviews research of core-substituted naphthalenediimides (cNDIs) in a comprehensive yet easily readable manner. Their synthesis, electrochemistry and spectroscopy are covered first with emphasis on the ability of cNDIs with electron donating substituents to absorb and fluoresce in all colors without global structural changes and cNDIs with electron withdrawing substituents to reach unprecedented extents of pi-acidity. The section on supramolecular chemistry covers face-to-face pi-stacks and peripheral hydrogen bonds, that on molecular recognition moves from pH and fluoride sensors to the binding to telomeric DNA in vivo and intercalation into pi-stacks and sticky tweezers. cNDIs can recognize and transport anions by functional anion-pi interactions. The section on electron transport describes cNDIs as air-stable n-semiconductors with high charge mobility and use as OFETs. Photoinduced electron transport by rainbow cNDIs has been used for the creation of artificial photosystems in solution, in bilayer membranes and on solid substrates. Examples include multicolor light harvesting architectures, organic solar cells, photosystems that can open up into ion channels, and supramolecular n/p-heterojunctions with antiparallel redox gradients. The review is highly interdisciplinary but should appeal most to organic, biosupramolecular and physical chemists.