Thioxobimanes

Dioxobimanes, colloquially known as bimanes, are a well-established family of N-heterobicyclic compounds that share a characteristic core structure, 1,5-diazabicyclo[3.3.0]octadienedione, bearing two endocyclic carbonyl groups. By sequentially thionating these carbonyls in the syn and anti isomers of the known (Me,Me)dioxobimane, we were able to synthesize a series of thioxobimanes, representing the first heavy-chalcogenide bimane variants. These new compounds were extensively characterized spectroscopically and crystallographically, and their aromaticity was probed computationally. Their potential role as ligands for transition metals was demonstrated by synthesizing a representative gold(I)-thioxobimane complex.

Electron-Deficient Benzo[de]isoquinolino[1,8-gh]quinoline Diamide π-Electron Systems

Synthetically versatile electron-deficient π-electron systems are urgently needed for organic electronics, yet their design and synthesis are challenging due to the low reactivity from large electron affinities. In this work, we report a benzo[de]isoquinolino[1,8-gh]quinoline diamide (BQQDA) π-electron system. The electron-rich condensed amide as opposed to the generally-employed imide provides a suitable electronic feature for chemical versatility to tailor the BQQDA π-electron system for various electronic applications. We demonstrate an effective synthetic method to furnish the target BQQDA parent structure, and highly selective functionalization can be performed on bay positions of the π-skeleton. In addition, thionation of BQQDA can be accomplished under mild conditions. Fine-tuning of fundamental properties and supramolecular packing motifs are achieved via chemical modifications, and the cyanated BQQDA organic semiconductor demonstrates a high air-stable electron-carrier mobility.

Tuning of the optoelectronic properties of peptide-appended core-substituted naphthalenediimides: the role of self-assembly of two positional isomers

This study demonstrates how the self-assembly pattern of two different and isomeric peptide-appended core-substituted naphthalenediimides (NDIs) affects the modulation of their optoelectronic properties. Two isomeric peptide-attached NDIs were synthesized, purified and characterized. Interchanging the position of attachment of the peptide units and the alkyl chains in the NDI has altered the respective self-assembling patterns of these isomeric molecules in the aggregated states. The isomer having a peptide moiety in the core position and the alkyl chain in the imide position (compound N1) forms face to face stacking or 'H' aggregates in aliphatic solvents including n-hexane, and n-decane, whereas compound N2, in which the peptide moiety is at the imide position and the alkyl chain is attached at the core position of NDI exhibits edge to edge stacking or J aggregates under the same conditions as it is evident from their UV-vis studies. The H aggregated species (obtained from N1) show inter-connected nanofibers, whereas the J aggregated species (obtained from N2) exhibit the morphology of helical nanoribbons. FT-IR and X-ray diffraction studies are in favor of the same aggregation behavior. The individual packing patterns of these two peptide-based isomers have a direct impact on their respective electrical conductivity. Interestingly, the H aggregated species shows 100 times greater current conductivity than that of the J aggregate. Moreover, it is only the H aggregated species that exhibits a photocurrent, and no such photocurrent response is observed with the J aggregates. Computational studies also support that different types of aggregation patterns are formed by these two isomeric molecules in the same solvent system. This unique example of tuning of optoelectronic behavior holds future promise for the development of new peptide-conjugated π-functional materials.

Preparation of substituted triphenylenes via nickel-mediated Yamamoto coupling

Nickel-mediated Yamamoto coupling provides a concise and efficient synthesis of triphenylene derivatives, including electron-deficient discotic mesogens.

Fluorination and chlorination effects on quinoxalineimides as an electron-deficient building block for n-channel organic semiconductors

The quinoxalineimide (QI) unit, containing the electron-withdrawing quinoxaline and imide groups, is an electron-deficient building block for organic semiconductor materials. In this study, three fluorinated or chlorinated QIs (QI-1F, QI-2F, and QI-2Cl), have been designed and developed. We report the impact of the fluorination or chlorination of the QI unit on the electronic structures and charge carrier transport properties as compared to unsubstituted QI (QI-2H) bearing the same n-hexyl side chains. The frontier molecular orbital energy levels downshifted with the incorporation of fluorine or chlorine atoms onto the π-framework of QI. Single-crystal structure analyses revealed that all QI-based molecules have an entirely planar backbone and are packed into two-dimensional slipped stacks with diagonal electronic coupling that enables two-dimensional charge carrier transport. Notably, the doubly fluorinated or chlorinated QIs formed compact molecular packing in the single-crystal structures through an infinite intermolecular network relative to unsubstituted QI (QI-2H). The field-effect transistor-based QI molecules exhibited typical n-channel transport properties. As compared to unsubstituted QI (QI-2H), the chlorinated QI exhibited improved electron mobilities up to 7.1 × 10⁻³ cm² V⁻¹ s⁻¹. The threshold voltages of the fluorinated or chlorinated QI devices were clearly smaller than that of QI-2H, which reflects the lowest unoccupied molecular orbital levels of the molecules. This study demonstrates that the fluorinated or chlorinated QIs are versatile building blocks in creating n-channel organic semiconductor materials.

Three fluorinated or chlorinated quinoxalineimide units (QI-1F, QI-2F, and QI-2Cl) have been designed and developed.

Thionated Perylene Diimide-Phenothiazine Dyad: Synthesis, Structure, and Electrochemical Studies

Perylene diimides (PDIs) are promising candidates for n-type semiconductor materials and, thus, for use in organic electronics. Thionation of the imide moiety provides an efficient strategy to control the donor-acceptor gap of these types of compounds, although the degree and selectivity of thionation can be hard to achieve. Through the design of a sterically encumbered PDI-phenothiazine dyad, a previously unattained geminal thionation pattern has been realized, providing the first example of a perylene-monoimide-monothioimide. The electrochemical and solid-state structural properties of this uniquely thionated dyad are reported and compared to those of the nonthionated parent molecule. It is found that thionation enhances the electron affinity of the PDI core, affecting electrochemical and spectroelectochemcial behavior of the dyad without significantly affecting the solid-state packing of the molecules.

Thionated naphthalene diimides: tuneable chromophores for applications in photoactive dyads

Thionation of naphthalene diimide and naphthalic imide phenothiazine dyads affords a systematic approach for tuning donor–acceptor energy gaps.

Determination of Controlled Self-Assembly of a Paracrystalline Material by Homology Modelling with Hybrid NMR and TEM

Controlling complexity, flexibility, and functionality of synthetic and biomimetic materials requires insight into how molecular functionalities can be exploited for steering their packing. A fused NDI‐salphen (NDI=naphthalene diimide) prototypic artificial photosynthesis material, DATZnS, is shown to be comprised of a phenazine motif, in which the alignment of electric dipole moments in a P2/c supramolecular scaffold can be modulated with bulky substituents. They can also be switched between parallel stacks of dipoles running antiparallel in the DATZnS‐H compared with parallel stacks of dipoles in polar layers running in opposite directions in the DATZnS(3′‐NMe) parent compound. Spatial correlations obtained from HETCOR spectra, collected with a long cross polarization contact time of 2 ms, reveal an antiparallel stacking for the DATZnS‐H homologue. These constraints and limited data from TEM are used to construct a structural model within the P2/c space group determined by the molecular C₂ symmetry. By using homology modelling, a pseudo octahedral coordination of the Zn is shown to follow the packing‐induced chirality with enantiomeric pairs of the Λ and Δ forms alternating along antiparallel stacks. The model helps to understand how the steric hindrance modulates the self‐assembly in this novel class of fused materials by steric hindrance at the molecular level.

Selective thionation of naphtho[2,3-b]thiophene diimide: tuning of the optoelectronic properties and packing structure

Naphtho[2,3-b]thiophene diimide was selectively thionated to afford the corresponding dicarboxy-dithiocarboxy diimide with a low-lying LUMO of −4.2 eV.

A thiocarbonyl-containing small molecule for optoelectronics

We report the synthesis, characterization, and device properties of a novel thiocarbonyl iso-DPP derivative, namely 1,3,4,6-tetraphenylpyrrolo[3,2-b]pyrrole-2,5(1H,4H)-dithione.

Synthesis and characterization of novel dibenz[a,c]anthracenedicarboxythioimides: the effect of thionation on self-assembly

The effect of thionation on the formation of columnar liquid crystalline phases of dibenzanthracenedicarboximides as well as their self-association in solution is described.