Crystal Growth, Intermolecular Noncovalent Interactions, and Photoluminescence Properties of Halogenated Phthalic Anhydride-Based Organic Charge Transfer Cocrystals

Abstract

Organic charge-transfer cocrystals are composed of an electron-rich donor molecule and an electron-deficient acceptor molecule, which are bonded together by intermolecular noncovalent interactions such as π−π interactions, hydrogen bonds, halogen bonds, and charge-transfer interactions. These noncovalent interactions influence the cocrystal packing structures and the photoluminescence properties. Herein, four charge transfer cocrystals, pyrene-tetrafluorophthalic anhydride (TFPA), perylene-TFPA, pyrene-tetrachlorophthalic anhydride (TCPA), and perylene-TCPA, were grown by the slow cooling method and the influence of intermolecular noncovalent interactions on the photoluminescence properties were investigated. Cocrystals of pyrene-TFPA and pyrene-TCPA exhibit a yellow rod-like morphology, while both perylene-TFPA and perylene-TCPA exhibit red rod-like shapes. Results indicate that the C−H•••X (X = F, Cl, or O) interactions, π−π interactions, and charge-transfer interactions are dramatically affected by the energy difference between the HOMO of the donor and the LUMO of the acceptor. Meanwhile, for the same acceptor molecules, the positions of the photoluminescence peaks of the cocrystals red-shifted with the enhancement of weak noncovalent interactions, which paved the way to tuning the optical properties of charge transfer cocrystals.

Halogen-bonded charge-transfer co-crystal scintillators for high-resolution X-ray imaging

“…4a and b , right). 35 On one hand, the charge transport induced by head-to-head halogen bonding increases the conductivity, and on the other hand it limits the molecular rotation and improves the luminescence properties of the co-crystal. The stacking patterns predicted by theoretical calculations are consistent with the ESP results.…”

Large-Sized Nitrogen-Containing Biphenyl-Doped p-Terphenyl Crystals with Tunable Luminescence for Organic Scintillators

“…Therefore, the energy is transferred to the dopant molecules after the host molecule is excited, achieving tunable emission from blue to green light. The B3LYP hybrid density functional and the 6-311G+(d, p) basis set were used to calculate the energy level diagrams of the host and dopant molecules, as shown in Figure S10. Theoretical calculation results show that energy can be transferred from the host molecule to the dopant molecules after the excited host molecule, ultimately achieving the tunable luminescence of nitrogen-containing biphenyl-doped p -terphenyl crystals.…”

Solid-State Assembly and Photoluminescent Behavior of 5-(9H-Carbazol-9-yl)isophthalic Acid–Based Molecular Crystals Influenced by Solvents and Organic Counterparts

“…Molecular crystals with desirable structures and efficient photoluminescence are highly important for multiscenario field applications in displaying, , sensing, , optical waveguide, and optoelectronics devices. − Lots of organic crystalline materials with tunable emission color, long-lived lifetime, and/or high quantum yield have been designed and manufactured by powerful cocrystal engineering strategy. − Besides the enhanced charge transfer (CT) interactions between electron-rich donor (D) and electron-withdrawing acceptor (A), − weak intermolecular interactions (π–π stacking, hydrogen bond, halogen bond, dipole–dipole, and so on) have also become main forces to drive two or more components into highly ordered solid-state superstructures. − These weak interactions have precisely dominated the molecular packings in the rigid crystal matrix, resulting in unpredictable polymorphism, segregated AD and/or ADA alignments, and exciton coupling strgenth. , More importantly, the different stacking structures have well-tailored the band gaps and exciton couplings, responsible essentially for the unexpected geometry stability and optoelectronic characteristics . However, the stacking patterns are extremely complicated and highly sensitive to the molecular structure and crystal growth environment, and purposeful controls on the photoluminescence still remain a great challenge. ,− Great efforts have thus been devoted to the chemical modifications of the constitute part by introducing multiple interacting sites or skillful selection of the compatible D–A pairs to obtain high-emissive and high-stable molecular crystals …”