Liaocheng University

Cocrystal engineering offers the opportunity to achieve noncovalent synthesis of functional molecules with tunable luminescent features. In this study, Pe-4F2CN co-crystal was fabricated by using perylene (Pe) and tetrafluoroterephthalonitrile (4F2CN) through charge-transfer (CT)-induced assembly. The co-crystal exhibits two distinct emission bands and pronounced piezochromic properties, achieving the tunable luminescence from yellow to red upon compression. By the analysis of crystal structure and high-pressure IR spectroscopy combined with theoretical calculations, it revealed that the enhanced π-π and C-H···N interactions would regulate the charge-transfer process, thereby leading to the redshifts in photoluminescence (PL) and decreased emission intensity. This research not only demonstrates a novel approach to achieving tunable luminescence through pressure modulation, but also deepens the understanding of the relationship between intermolecular interactions and photophysical properties, which provides further guidance for the design of piezochromic materials.

The structure of polyphenolic compounds plays a pivotal role in determining their functional efficacy. Moreover, the presence of bile salt surfactants can significantly impact their metabolism. Hence, this study employed multi-spectroscopic methods to explore the binding mechanism of Quercetin (Que) and Taxifolin (Tax, dihydroquercetin) with bovine hemoglobin (HB), influenced by the addition of sodium taurodeoxycholate (NaTDC). The results indicate that, through the static quenching mechanism, nearly a single Que. or Tax molecule can spontaneously form a complex on each HB chain. This process is driven by Van der Waals forces, hydrophobic interaction, and hydrogen bonds. During the interaction, the secondary structure of HB chains undergoes changes with an enhanced hydrophobicity. The hydrogenation of C2C3 double bond of flavonols increases the structural flexibility and helps to close to the active sites of HB, resulting in the stronger binding affinity of Tax on HB chains than Que. Additionally, the presence of this double bond exerts a notable influence on the physicochemical properties of polyphenols, such as solubility, antioxidant activity, and antibacterial activity. Specifically, the solubility of pure Tax in water, and its bacteriostatic effect against Klebsiella Pneumoniae (KP) and Methicillin-resistant Staphylococcus Aureus (MRSA), are superior to that of Que. The C2C3 double bond of Que. make it exhibiting better antioxidant ability than Tax. After interacting with HB, the antioxidant capacity are enhanced, and the bacteriostatic effects are either weakened or remain essentially unchanged compared to those of pure Que./Tax. The addition of NaTDC can enhance the low solubility of Que./Tax and regulate their interaction strength with HB, thereby further influencing their bioavailability. For the Tax/Que-HB mixed system, the presence of NaTDC strengthens their antioxidant capacity, but does not affect the antimicrobial activity basically. These findings hold significant practical implications for enhancing the therapeutic efficacy and bioavailability of natural products.

As a new type of organic porous crystalline material connected with covalent bonds, covalent organic frameworks (COFs) have shown unique advantages in many fields. However, the preparation of COFs membrane that are easy to prepare and can be applied multiple times still is a challenge. Here, 2,5-Dimethoxybenzene-1,4-dicarboxaldehyde (Dma) and 4,4',4''-(1,3,5-Triazine-2,4,6-triyl) trianiline (TAPT) was used as a reactant and Dma-TAPT fiber membranes with good crystallinity and stability were prepared through electrospinning technology and solvothermal in-situ growth. The XRD, SEM, ¹³C NMR, IR, and XPS, etc. were used to characterize the structure of obtained membrane. The prepared membranes not only showed fluorescence detection for acid but also realize the visual detection via a portable smartphone. The density functional theory calculation and experimental results verified that the methoxy group provide site for the interaction with H⁺ in acid. Additionally, because of the increase of light absorption capacity the photothermal efficiency of COFs after acidification was improved by 17.4 % for the COFs before acidification. The research provides ideas for designing new sensitive and recyclable pH sensors.