Bisphosphonium Benzene Diimides.

The incorporation of cationic groups onto electron-poor compounds is a viable strategy for achieving potent electron acceptors, as evidenced by reports of air-stable radical forms of large aromatic diimides such as naphthalene and perylene diimides. These ions have also been observed to exhibit anion-π interaction tendencies of interest in molecular recognition applications. The benefits of phosphonium incorporation, however, have not yet been extended to the smallest benzene diimides.

Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides.

We report the synthesis and characterization of naphthalene and anthracene scaffolds end-capped by cyclic imides. The solid-state structures of the -phenyl derivatives, determined by X-ray crystallography, reveal changes in packing preference based on the number of aromatic rings in the core. The optical and electronic properties of the title compounds compare favorably with other previously described isomers and expand the toolbox of electron-deficient aromatic compounds available to organic materials chemists.

Second Generation of Cata-Annulated Azaacene Bisimides: Towards Electron-Accepting Materials.

This work presents the 2 generation of cata-annulated azaacene bisimides with increased electron affinities (up to -4.38 eV) compared to their consaguine conventional azaacenes. These compounds were synthesized via Buchwald-Hartwig coupling followed by oxidation with MnO .

Improved Syntheses of Halogenated Benzene-1,2,3,4-Tetracarboxylic Diimides.

The preparation of halogenated benzene-1,2,3,4-tetracarboxylic diimide derivatives is challenging because of the possibility of competitive incorrect cyclizations and SAr reactivity. Here, we demonstrate that bypassing traditional cyclic anhydrides and instead directly reacting dihalobenzene-1,2,3,4-tetracarboxylic acids with primary amines in acetic acid solvent successfully provides a range of desirable -diimide products in good yields. Furthermore, we demonstrate that sterically challenging -derivatizations can be readily achieved under microwave reactor conditions.

Cata-Annulated Azaacene Bisimides.

Ultra-electron-deficient azaacenes were synthesized via Buchwald-Hartwig coupling of ortho-diaminoarenes with chlorinated mellophanic diimide followed by oxidation of the intermediate N,N'-dihydro compounds with MnO or PbO . The resulting cata-annulated bisimide azaacenes have ultrahigh electron affinities with first reduction potentials as low as -0.35 V recorded for a tetraazapentacene.

A Highly Stabilized Phosphonium Ylide that Forms Supramolecular Dimers in Solution and the Solid State.

This work describes the unexpected formation of an unusual phosphonium ylide when attempting the synthesis of bisphosphonium pyromellitic diimides. Spectroscopic and crystallographic characterization reveals that a combination of π-π and CH⋅⋅⋅O interactions leads to supramolecular homodimerization of the ylide both in solution and in the solid-state. Only strong acids are able to protonate the ylide, which is otherwise inert to Wittig and alkylation reactivity.

Redox-Active Heteroacene Chromophores Derived from a Nonlinear Aromatic Diimide.

This work describes a three-step chromatography-free protocol for the synthesis of a novel organic materials building block, dichlorinated mellophanic diimide (MDI), that is shown to undergo nucleophilic substitution with a variety of disubstituted benzenes to yield a series of chromophores. Furthermore, 1,2,4,5-tetrasubstituted benzenes can be used to synthesize tetraimide heteropentacene derivatives endcapped by MDI motifs. The fine-tuning effects of heteroatom identity were investigated by UV-vis and fluorescence spectroscopy, cyclic and differential pulse voltammetries, and density functional theory calculations.

Nuptial gift chemistry reveals convergent evolution correlated with antagonism in mating systems of harvestmen (Arachnida, Opiliones).

Nuptial gifts are material donations given from male to female before or during copulation and are subject to sexual selection in a wide variety of taxa. The harvestman genus has emerged as a model system for understanding the evolution of reproductive morphology and behavior, as transitions between solicitous and antagonistic modes of courtship have occurred multiple times within the lineage and are correlated with convergence in genital morphology. We analyzed the free amino acid content of nuptial gift secretions from five species of using gas chromatography-mass spectrometry.

Pyridinium-Functionalized Pyromellitic Diimides with Stabilized Radical Anion States.

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.

X-Shaped Oligomeric Pyromellitimide Polyradicals.

The synthesis of stable organic polyradicals is important for the development of magnetic materials. Herein we report the synthesis, isolation, and characterization of a series of X-shaped pyromellitimide (PI) oligomers (X-R, n = 2-4, R = Hex or Ph) linked together by single C-C bonds between their benzenoid cores. We hypothesize that these oligomers might form high-spin states in their reduced forms because of the nearly orthogonal conformations adopted by their PI units.