1D Mixed-Stack Cocrystals Based on Perylene Diimide toward Ambipolar Charge Transport

A Computational Design of Covalently Bonded Mixed Stacking Cocrystals

In this study, a computational design of a new type of donor-acceptor mixed stacking cocrystals is introduced. Our approach involves functionalizing trisilasumanene frameworks with electron-donating groups (-CH3, -OH, -NH2) and electron-withdrawing groups (-F, -CN), and then stacking donors and acceptors alternatively while connecting them either by sp3- and sp-carbon chains. Using the B3LYP-D3/6-31+G(d) level of theory, we demonstrate that these covalently bonded cocrystals can overcome the issue of thermal and mechanical instabilities observed in the non-covalently mixed stacking. Furthermore, modifying donor and acceptor groups can vary the bandgaps, approximated by the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gaps, from 1.50 to 3.50 eV. The results also predict the covalently bonded mixed stacking cocrystals having much larger conductance via Yoshizawa model. In addition, variations in bridge lengths were found to have a small effect on the HOMO-LUMO gaps but allow for a new control parameter regarding the porosity of the materials. These results encourage experimental explorations.

Planar Chiral Charge-Transfer Cyclophanes: Convenient Synthesis, Circularly Polarized Light-Responsive Photothermal Conversion and Supramolecular Chiral Assembly

We report herein a series of macrocycles in which the densely π-stacked charge-transfer (CT) donor/acceptor with naphthalenediimides (NDIs) or perylene diimide (PDI) as acceptor moiety pairing various donor moieties are locked by covalent bond. The X-ray crystallography of C8BDT-NDI reveals a short intramolecular π-stacking distance around 3.4 Å and the existence of intermolecular donor/acceptor π-stacking (3.7 Å). The intramolecular CT is highly dependent on the electron-donating ability of donor moiety and replacing carbazole (C8KZ) with benzo[1,2-b:4,5-b']dithiophene (C8BDT) or dihydroindolo[3,2-b]indole (C8DN) redshift CT absorption into NIR region. Notably, both C8BDT-NDI and C8DN-NDI demonstrate excellent photothermal performance, which is a result of the active non-radiative pathways. Interestingly, the different molecular symmetry between donor and acceptor moiety in cyclophanes endow C8BDT-NDI and C8DN-NDI with intrinsic planar chirality. The enantiomeric C8BDT-NDI shows chiral selectivity for incident light, i.e., when irradiated by left-circularly polarized light, (R)-C8BDT-NDI is more sensitive and a higher maximum stable temperature is achieved. While, enantiomeric C8DN-NDI pack with different orientations forming M- and P-handedness helix, respectively, demonstrating molecular planar chirality being transferred and amplified through molecular assembly. These results provide insight into the intramolecular charge transfer in enforced D/A π-stacks in which CT interactions and planar chirality would be engineered through structural control.

Donor-acceptor complex formation by social self-sorting of polycyclic aromatic hydrocarbons and perylene bisimides

Self-assembly versus complexation with polycyclic aromatic hydrocarbon (PAH) guest molecules is studied for a series of perylene bisimides (PBIs). Bulky imide substituents at the PBI guide their self-assembly into dimer aggregates with null-type exciton coupling. Host-guest titration experiments with perylene and triphenylene PAHs afford 1 : 1 and 1 : 2 complexes whose properties are studied by single crystal X-ray analysis and UV/Vis and fluorescence spectroscopy.

Assembling photoactive materials from polycyclic aromatic hydrocarbons (PAHs): room temperature phosphorescence and excimer-emission in co-crystals with 1,4-diiodotetrafluorobenzene

Co-crystallization of PAHs with a polyhalogenated co-former afforded three novel co-crystals, which display remarkable features such as mechanochemical interconversion, photoreactivity, excimer fluorescence, and RTP phosphorescence in the solid state.

Unraveling Semiconductor Properties of Mixed Stack Donor Acceptor Cocrystals of Pyrene Derivatives and TCNQ: Effect of Crystal Packing versus Super-exchange Mechanism

We have discussed semiconductor property of two reported 2:1 and 1:1 charge transfer donor acceptor cocrystals with mixed ··DDADDA·· stacking. These cocrystals (CCDC 1212856 and 1212858) are comprising of 2-phenyl-3-(pyrene-2-yl)acrylonitrile...

The competitive role of C–H⋯X (X = F, O) and π–π interactions in contributing to the degree of charge transfer in organic cocrystals: a case study of heteroatom-free donors with p-fluoranil (FA)

Four binary organic charge transfer cocrystals were grown by the slow cooling method. The competitive role of C–H⋯X (X = F, O) and π–π interactions in contributing to the degree of charge transfer in the cocrystals was investigated.

Organic Cocrystals: Recent Advances and Perspectives for Electronic and Magnetic Applications

Cocrystal engineering is an advanced supramolecular strategy that has attracted a lot of research interest. Many studies on cocrystals in various application fields have been reported, with a particular focus on the optoelectronics field. However, few articles have combined and summarized the electronic and magnetic properties of cocrystals. In this review, we first introduce the growth methods that serve as the basis for realizing the different properties of cocrystals. Thereafter, we present an overview of cocrystal applications in electronic and magnetic fields. Some functional devices based on cocrystals are also introduced. We hope that this review will provide researchers with a more comprehensive understanding of the latest progress and prospects of cocrystals in electronic and magnetic fields.

Creating Organic Functional Materials beyond Chemical Bond Synthesis by Organic Cocrystal Engineering

Organic cocrystal engineering refers to two or more organic molecules stoichiometrically combined and held together by noncovalent intermolecular interactions, which differs from standard chemical synthesis involving covalent bond breakage and formation. Organic cocrystals have unique properties and offer a new strategy for creating enhanced organics. First, however, some key questions need to be addressed: How do diverse monomers affect the intermolecular interaction kinetics during cocrystallization? How do the intermolecular forces in cocrystals affect cocrystal functions? In this Perspective, the definition and advantages of organic cocrystal engineering, specifically in the construction of a reliable intermolecular interaction-stacking structure-performance relationship, are outlined. Additionally, recent developments in the field and the questions above are discussed. Finally, a brief conclusion and some hints on likely future developments are provided.