Reported herein is the first isolation of tetracyanonaphthalenediimide [NDI(CN) 4 ]a nd its radical anion, and structural elucidation through spectroscopic and X-rayd iffraction studies.T he radical anion shows remarkable stability and was purified by chromatography,w hich is unique for planar radical anions.T he stability results from multiple hydrogen bonds to the counter ion and through an array of intramolecular noncovalent interactions.T he radical anion revealed one of the strongest NDI p-p interactions (3.268 ). Electrochemical studies of [NDI(CN) 4 ]c onfirm its extraordinarily low-lying LUMO (À5.0 eV), rendering it one of the strongest electron-deficient planar p systems to be isolated. The manifold potential, whichremained unknown to date,can now be explored for these open-and closed-shell planar p systems.Planar p-conjugated radical anions [1][2][3][4] and highly electron-Angewandte Chemie

Herein we report the first applications of TCNQ as a rapid and highly sensitive off-the-shelf cyanide detector. As a proof-of-concept, we have applied a kinetically selective single-electron transfer (SET) from cyanide to deep-lying LUMO orbitals of TCNQ to generate a persistently stable radical anion (TCNQ(•-)), under ambient condition. In contrast to the known cyanide sensors that operate with limited signal outputs, TCNQ(•-) offers a unique multiple signaling platform. The signal readability is facilitated through multichannel absorption in the UV-vis-NIR region and scattering-based spectroscopic methods like Raman spectroscopy and hyper Rayleigh scattering techniques. Particularly notable is the application of the intense 840 nm NIR absorption band to detect cyanide. This can be useful for avoiding background interference in the UV-vis region predominant in biological samples. We also demonstrate the fabrication of a practical electronic device with TCNQ as a detector. The device generates multiorder enhancement in current with cyanide because of the formation of the conductive TCNQ(•-).

The synthesis and isolation of two-electron reduced naphthalenediimides is reported. A doubly zwitterionic structure is observed for the first time in a naphthalene moiety, which aids in its stabilization.

Reported herein is the first isolation of tetracyanonaphthalenediimide [NDI(CN) 4 ]a nd its radical anion, and structural elucidation through spectroscopic and X-rayd iffraction studies.T he radical anion shows remarkable stability and was purified by chromatography,w hich is unique for planar radical anions.T he stability results from multiple hydrogen bonds to the counter ion and through an array of intramolecular noncovalent interactions.T he radical anion revealed one of the strongest NDI p-p interactions (3.268 ). Electrochemical studies of [NDI(CN) 4 ]c onfirm its extraordinarily low-lying LUMO (À5.0 eV), rendering it one of the strongest electron-deficient planar p systems to be isolated. The manifold potential, whichremained unknown to date,can now be explored for these open-and closed-shell planar p systems.

The naphthalenediimide (NDI) scaffold in contrast to its higher congeners possess low‐fluorescence. In spite of elegant synthetic developments, a highly emissive NDI is quite rare to find, as well as, a green‐light‐emitting NDI is yet to be explored. Herein, we report a novel class of symmetric and asymmetric NH2‐substituted core‐NDIs (1–5) with tunable fluorescence in the visible region and extending to the NIR frontier. Importantly, the bis‐NH2‐substituted NDI 2 revealed quantum yield, Φf of ≈81 and ≈68 % in toluene and DMSO, respectively, suggesting versatility of the fluorophore in a wide range of solvent polarity. The dye 1 is shown to be the first NDI‐based green‐light emitter. The donor piperidine group in 5 diminish the Φf by 40‐fold providing a lever to modulate the excited‐state intramolecular proton transfer (ESIPT) process. Our synthetic protocol applies a Pd catalyst and a benign hydride source simplifying the non‐trivial −NH2 group integration at the NDI‐core. TD‐DFT calculations predicted strong intramolecular hydrogen bonds in the excited state in the bulk nonpolar medium and responsiveness to solvent polarity. The maximization of the NDI emission outlined here would further boost the burgeoning repertoire of applications of the NDI scaffold.