Reticular Synthesis of One-Dimensional Covalent Organic Frameworks with 4-c sql Topology for Enhanced Fluorescence Emission.

Covalent organic frameworks (COFs) have been extensively investigated due to their unique structure, porosity, and functionality. However, at the topological level, COFs remain as two-dimensional (2D) or three-dimensional (3D) structures, while COFs with one-dimensional (1D) topology have not been systematically explored. In this work, we proposed a synthetic strategy for the construction of 1D-COFs based on non-linear edges and suitable high-symmetry vertices. Compared with their 2D-COFs counterparts, the 1D-COFs with AIEgens located at the vertex of the frame exhibited enhanced fluorescence. The density functional theory (DFT) calculations revealed that the dimensional-induced rotation restriction (DIRR) effect could spontaneously introduce additional non-covalent interactions between the strip frames, which could substantially diminish non-radiative transitions. This work also provides protocols for the design of 1D-COFs and a guidance scheme for the synthesis of emitting COFs.

A ketone-functionalized carbazolic porous organic framework for sensitive fluorometric determination of p-nitroaniline.

A novel ketone-functionalized carbazolic porous framework named PBPMCz is presented for fluorometric determination of p-nitroaniline (PNA). PBPMCz was prepared by FeCl3-promoted oxidative coupling polymerization of 1,3,5-tris((4-(9H-carbazol-9-yl)phenyl)methanone-1-yl)benzene. The polymer possesses a BET surface area of above 907 m2∙g-1 with a pore volume of 0.72 cm3∙g-1. Compared to the ketone-free framework, the green fluorescence of the probe PBPMCz is more strongly quenched by PNA. Figures of merit include (a) excitation/emission wavelengths of 366/540 nm; (b) a Stern-Volmer constant (Ksv) of 2.2 × 104 M-1, and (c) a detection limit of 1.1 µM. Furthermore, PBPMCz shows different quenching behaviors of PNA compared with o-nitroaniline and m-nitroaniline. The excellent performance of the fluorescent probe is ascribed to the abundant carbazole sites and ketone groups in PBPMCz. These facilitate the electron transfer and hydrogen-bonding interactions between PNA and the polymer. Graphical abstract Schematic presentation of a luminescent carbazolic porous organic framework (CzPOF) modified with keto groups. It shows ultra-sensitivity to quenching by PNA over other nitroaniline isomers.

Copine A Interacts with Actin Filaments and Plays a Role in Chemotaxis and Adhesion.

Copines make up a family of calcium-dependent, phospholipid-binding proteins found in numerous eukaryotic organisms. Copine proteins consist of two C2 domains at the N-terminus followed by an A domain similar to the von Willebrand A domain found in integrins. We are studying copine protein function in the model organism, Dictyostelium discoideum, which has six copine genes, cpnA-cpnF. Previous research showed that cells lacking the cpnA gene exhibited a cytokinesis defect, a contractile vacuole defect, and developmental defects. To provide insight into the role of CpnA in these cellular processes, we used column chromatography and immunoprecipitation to isolate proteins that bind to CpnA. These proteins were identified by mass spectrometry. One of the proteins identified was actin. Purified CpnA was shown to bind to actin filaments in a calcium-dependent manner in vitro. cpnA- cells exhibited defects in three actin-based processes: chemotaxis, cell polarity, and adhesion. These results suggest that CpnA plays a role in chemotaxis and adhesion and may do so by interacting with actin filaments.