Synthesis, self-assembly and nonlinear optical activity of selenium-annulated perylene diimide

Electronic and Nonlinear Optical Properties of B(III)-Submonoazaporphyrin-π-Diimide Compounds: A Density Functional Theory Study

Three hypothetical complexes were designed using diimides (PMDI, NTCDI, and PTCDI) as the acceptor unit and B(III)-submonoazaporphyrin (1) as the donor unit. These complexes have smaller HOMO-LUMO energy gaps (3.39-3.96 eV) than pristine 1 (6.61 eV). Further, the energy gap can be tuned by changing the number of benzene rings of these diimides. Remarkably, these proposed complexes possess considerable first hyperpolarizabilities (β0) (4865-6921 a.u.), and the regularity of the β0 values remained the same in the gas phase and toluene solvent conditions. There is an inverse relationship between the energy gap and the polarizability/first hyperpolarizability. In addition, absorption spectra, frontier molecular orbitals, and hole electron distributions were obtained using time-dependent density functional theory calculations to emphasize the relationship between structure and properties. Ultraviolet-Visible absorption spectra reveals that all complexes show satisfying IR working regions. Further analysis of the first hyperpolarizability density reveals the nature of the excellent NLO properties of the studied systems. This study can provide valuable insights for the development of potential high-performance NLO molecules.

Bowl-Shaped Bispyrrole-Fused Perylene-diimide and Its Anions

Incorporating two pyrrole subunits at the bay positions of perylene-diimide has been a long-pursued goal since 2009, but it has not been achieved due to high strain. Herein, via one step Buchwald-Hartwig reaction, PDI-2N was successfully generated with a bowl depth of 1.52 Å. Though with electron-rich pyrrole embedding, PDI-2N's radical anion and dianion were facilely prepared and were investigated both experimentally and theoretically. Moreover, PDI-2N crystallized in different manners under distinct conditions, and it formed tubular crystals with infinite two-directional columnar stacking under DMF conditions. This finding develops a dream bowl-shaped PDI derivative that holds great promise in organoelectronics.

Nonlinear Optical Properties of Pyrene Derivatives Based on a Donor-Acceptor Structure and Its Polyurethane Composites

Two pyrenyl Schiff base derivatives with π conjugated structures (B2 and B3) were designed and synthesized. Then, B2 and B3 were added into polyurethane to obtain doped and bonded polyurethane nonlinear optical materials (B2/PU and B3/PU), respectively. The synthesized B2, B3, and polyurethane nonlinear optical materials were tested by a nanosecond (ns) and picosecond (ps) pulse Z-scan at a 532 nm wavelength. Due to the two-photon absorption-induced excited state absorption (TPA-ESA), B2, B3, and polyurethane nonlinear optical materials show reverse saturable absorption (RSA). From a quantum chemistry calculation, it can be concluded that the RSA of B2 and B3 comes from the large π conjugated system and intramolecular charge transfer. Furthermore, B2, B3, and the polyurethane nonlinear optical materials show good optical limiting. B2/PU and B3/PU not only have excellent nonlinear optical properties but also have good transmittance, thermal stability, and processability of polyurethane materials. The combination of pyrenyl Schiff base derivatives and polyurethane materials greatly improves the application of nonlinear small molecules in the field of optical limiting and all-optical switching.

Assembling of Perylene, Naphthalene, and Pyromellitic Diimide-Based Materials and Their Third-Order Nonlinear Optical Properties

π-conjugated aromatic diimides with chemical stability, heat resistance, and redox activity have attracted more attention due to their excellent fluorescence quantum yield in solution. The planar perylene diimide (PDI) derivatives generally have aggregation-induced emission quenching in the solid state, while the cyclic trimers based on pyromellitic diimides (PMDIs), naphthalene diimides (NDIs), and PDIs can increase the fluorescence quantum yield in the solid state and have large two-photon absorption cross section, which can be used as excellent nonlinear optical (NLO) materials. Therefore, this paper will study the effects of multiple assembly modes of the three monomers on the NLO responses of materials. It was found that the assembly modes of 2PMDI-1NDI and 2NDI-1PDI exhibit larger third-order NLO response (γ) values, which was due to the larger conjugate surface of PDI effectively reducing the energy gap between the HOMO and LUMO. Compared with other assembly methods, 2PMDI-1NDI and 2NDI-1PDI were conducive to causing redshifts (150 nm) in the absorption spectrum. Therefore, the larger conjugate surface of PDI and the assembly mode of the isosceles triangle were more favorable for intramolecular charge transfer, thus improving its NLO properties.

Perylene diimide-based treatment and diagnosis of diseases

Integrated treatment using imaging technology to monitor biological processes for the precise treatment and diagnosis of diseases to improve treatment outcomes is becoming a hot topic. Accordingly, perylene diimide (PDI) has excellent photothermal conversion and photostability, which can be used as a good material for disease treatment and diagnosis. Herein, we review the latest research progress on the real-time diagnosis of related diseases based on perylene diimide probes in the aspects of bioimaging, detection of biomarkers and determination of the pH in living cells. Furthermore, perylene diimide-based multifunctional nano-delivery systems are particularly emphasized, showing great therapeutic potential in the field of image-guided combination therapy in tumor therapy. Finally, the great opportunities and challenges still faced by perylene diimide before entering the clinic are comprehensively analyzed.