Pyridinium-Functionalized Pyromellitic Diimides with Stabilized Radical Anion States

Abstract

In this work, we report the stabilization of the reduced states of pyromellitic diimide by charge-balancing the imide radical anions with cationic pyridinium groups attached to the aromatic core. This structural modification is confirmed by single-crystal X-ray diffraction analysis. Characterization by (spectro)electrochemical experiments and computations reveal that the addition of cationic groups to an already electron-deficient ring system results in up to +0.57 V shifts in reduction potentials, largely as a consequence of charge screening and lowest unoccupied molecular orbital-lowering effects. This formal charge-balancing approach to stabilizing the reduced states of electron-deficient pyromellitic diimides will facilitate their incorporation into spin-based optoelectronic materials and devices.

Amino‐Functionalization of Vinyl‐Substituted Aromatic Diimides by Quantitative and Catalyst‐Free Hydroamination**

“…[6] The significant downfield shifts of the terminal vinyl protons of vNDI1 indicate deshielding by the electron-withdrawing nature of NDI and are comparable to those of methyl acrylate (5.82 ppm and 6.41 ppm) which has been reported to react with amines. [7] Indeed, when dibutylamine (DBA) was added to a solution of vNDI1 at 298 K, the 1 H NMR of vNDI1 was fully converted, as shown in Figure 1b. After careful characterization, we confirmed that the product was an amine monoadduct, vNDI1-DBA (Figures S9 and S10).…”

“…BDI-Br2 was synthesized according to the literature. [7] A similar procedure to the synthesis of vNDI2 with BDI-Br2 (200 mg, 0.29 mmol) afforded vBDI2 as a light yellow solid (164 mg, 97%…”

Azine Steric Hindrances Switch Halogen Bonding to N‐Arylation upon Interplay with σ‐Hole Donating Haloarenenitriles

“…[61][62][63] Only a few cases of conventional S N Ar reactions, where EWG groups activate the Xbound ipso-carbon toward the nucleophilic attack have been reported. These reactions include 2,4-dinitrobromobenzene, [64,65] 2,4-dinitroiodobenzene, [66] 2,4,6-trinitroiodobenzene, [67] tetrabromocatechol, [68][69][70] bromopyromellitic diimide, [71] and 2,3dibromonaphthalene-1,4,5,8-tetracarboxylic acid bisimide [72,73] as the arylation agents. All these reactions were conducted at high to moderate temperatures depending on the activating effect of substituents.…”

Redox-Active Heteroacene Chromophores Derived from a Non-Linear Aromatic Diimide

“…The 1,2,5,6 structural isomer of NDI is known 13 and recent synthetic developments have also enabled the preparation of anthracene, 14 pyrene 15 , coronene, 16 and hexacene diimides, 17,18 in addition to larger nanographene polyimide systems. 19,20 Over the course of our investigations into core-functionalization chemistry of pyromellitic diimide (PMDI), 21 we became interested in the other benzene diimide structural isomer, which has been termed mellophanic diimide (MDI) in the literature (Figure 1). 22,23 We found this angled benzene diimide isomer to be an interesting target because unlike the linear PMDI, the angled MDI core positions are ortho to each other and thus should be able to access a wider selection of nucleophilic substitution and annulation reactivity.…”