Photophysical implications of ring fusion, linker length, and twisting angle in a series of perylenediimide-thienoacene dimers

Efficacious and sustained release of an anticancer drug mitoxantrone from new covalent organic frameworks using protein corona

Solid porous and crystalline covalent organic frameworks (COFs) are characterized by their higher specific BET surface areas and functional pore walls, which allow the adsorption of various bioactive molecules inside the porous lattices. We have introduced a perylene-based COF, PER@PDA-COF-1, which acts as an effective porous volumetric reservoir for an anticancer drug, mitoxantrone (MXT). The drug-loaded COF (MXT-PER@PDA-COF-1) exhibited zero cellular release of MXT towards cancer cells, which can be attributed to the strong intercalation between the anthracene-dione motif of the drug and the perylene-based COF backbone. Here, we have introduced a strategy involving the serum-albumin-triggered intracellular release of mitoxantrone from MXT-PER@PDA-COF-1. The serum albumin acts as an exfoliating agent and as a colloidal stabilizer in PBS medium (pH = 7.4), rapidly forming a protein corona around the exfoliated COF crystallites and inducing the sustained release of MXT from the COF into tumorigenic cells.

Facile Azabenz-Annulations through UV-induced Photocyclization: A Promising Method for Perylenediimide-Based Organic Semiconductors

The derivatization of perylenediimides (PDIs) by bay decoration is essential for the development of PDI-based semiconductors owing to their excellent photoelectric properties. Herein, four bis-azabenz-annulated PDIs (bis-AzaBPDIs) are concisely synthesized in high yields through ultraviolet-induced photocyclization, where the reaction processes including aldimine condensation, cyclization, and oxidative re-aromatization are investigated. The optical characterizations and theoretical simulation reveal that the unique properties of the four bis-AzaBPDIs are comparable to their parent PDI. Organic field effect transistors with compounds 2, 3, or 4 as active layers indicated that all compounds showed unipolar electron transport properties with the mobilities of 1.1×10^-3 , 5.8×10^-4 , and 8.5×10^-6  cm²  V^-1  s^-1 , respectively. These results suggest the great potential of bis-AzaBPDIs as organic semiconductors. The easy preparation approach reported in this work would renew research interest in developing bis-AzaBPDI-based optoelectronic molecules.

Rational design and crystal structure prediction of ring-fused double-PDI compounds as n-channel organic semiconductors: a DFT study

In this study, we present an effective molecular design strategy to develop the n-type charge transport characteristics in organic semiconductors, using ring-fused double perylene diimides (DPDIs) as the model compounds. These dimeric-PDIs are formed by joining two separate PDI-units along their bay positions through ring fusion with pyrene, coronene and their N-doped counterparts. The bridging type has a significant steric effect at the annulation positions and controls the molecular geometry, mostly imposing buckling in the structure. The crystal structures of the designed compounds are also theoretically predicted. Thereafter, electronic structure parameters, molecular packing motifs, charge coupling strength and anisotropic mobilities were investigated to understand the charge transport efficiency of these systems. Among all the studied molecules, the 4N-coronene-fused DPDI (DPDI-6) is found to possess a lower LUMO level and a high EA, suggesting air-stable electron injection. Besides, DPDI-6 shows strong intermolecular electron coupling and possesses high electron mobility (μe = 5.31 × 10-2 cm2 V-1 s-1), which is better as compared with the other DPDI-compounds reported here. The DPDIs also possess optical absorption in the UV-visible region, opening up possible applications in organic photovoltaics. Besides, from the non-linear optical (NLO) analysis, DPDI-3 is found to possess the highest first-order hyperpolarizability, which is even better as compared with the reference compound urea, making it a promising candidate for NLO applications.

Pyrazolo[1,5-a]pyrimidines-based fluorophores: a comprehensive theoretical-experimental study

Fluorescent molecules are crucial tools for studying the dynamics of intracellular processes, chemosensors, and the progress of organic materials. In this study, a family of pyrazolo[1,5-a]pyrimidines (PPs) 4a-g has been identified as strategic compounds for optical applications due to several key characteristics such as their simpler and greener synthetic methodology (RME: 40-53%) as compared to those of BODIPYS (RME: 1.31-17.9%), and their tunable photophysical properties (going from ε = 3320 M-1 cm-1 and ϕ F = 0.01 to ε = 20 593 M-1 cm-1 and ϕ F = 0.97), in which electron-donating groups (EDGs) at position 7 on the fused ring improve both the absorption and emission behaviors. The PPs bearing simple aryl groups such as 4a (4-Py), 4b (2,4-Cl2Ph), 4d (Ph) and 4e (4-MeOPh), allow good solid-state emission intensities (QYSS = 0.18 to 0.63) in these compounds and thus, solid-state emitters can be designed by proper structural selection. The properties and stability found in 4a-g are comparable to commercial probes such as coumarin-153, prodan and rhodamine 6G. Ultimately, the electronic structure analysis based on DFT and TD-DFT calculations revealed that EDGs at position 7 on the fused ring favor large absorption/emission intensities as a result of the ICT to/from this ring; however, these intensities remain low with electron-withdrawing groups (EWGs), which is in line with the experimental data and allows us to understand the optical properties of this fluorophore family.