Project description:Hydrothermal reaction of 4,4-trimethylenedipyridine (tmdp) with ZnI2 under 175 degrees C yields a novel compound, {[Zn2I4(tmdp)2]n.[Zn2I4(tmdp)2]n}, which has a chiral infinite double-stranded helical structure consisting of two single-stranded helices of the same handedness.
Project description:Inspired by natural biological systems, chiral or handedness inversion by altering external and internal conditions to influence intermolecular interactions is an attractive topic for regulating chiral self-assembled materials. For coordination polymers, the regulation of their helical handedness remains little reported compared to polymers and supramolecules. In this work, we choose the chiral ligands R-pempH2 (pempH2 = (1-phenylethylamino)methylphosphonic acid) and R-XpempH2 (X = F, Cl, Br) as the second ligand, which can introduce C-H⋯π and C-H⋯X interactions, doped into the reaction system of the Tb(R-cyampH)3·3H2O (cyampH2 = (1-cyclohexylethylamino)methylphosphonic acid) coordination polymer, which itself can form a right-handed superhelix by van der Waals forces, and a series of superhelices R-1H-x, R-2F-x, R-3Cl-x, and R-4Br-x with different doping ratios x were obtained, whose handedness is related to the second ligand and its doping ratio, indicating the decisive role of interchain interactions of different strengths in the helical handedness. This study could provide a new pathway for the design and self-assembly of chiral materials with controllable handedness and help the further understanding of the mechanism of self-assembly of coordination polymers forming macroscopic helical systems.
Project description:Chiral transcription from the molecular level to the macroscopic level by self-organization has been a topic of considerable interest for mimicking biological systems. Homochiral coordination polymers (CPs) are intriguing systems that can be applied in the construction of artificial helical architectures, but they have scarcely been explored to date. Herein, we propose a new strategy for the generation of superhelices of 1D CPs by introducing flexible cyclohexyl groups on the side chains to simultaneously induce interchain van der Waals interactions and chain misalignment due to conformer interconversion. Superhelices of S- or R-Tb(cyampH)3·3H2O (S-1H, R-1H) [cyampH2 = S- or R-(1-cyclohexylethyl)aminomethylphosphonic acid] were obtained successfully, the formation of which was found to follow a new type of "chain-twist-growth" mechanism that had not been described previously. The design strategy used in this work may open a new and general route to the hierarchical assembly and synthesis of helical CP materials.
Project description:The 3D coordination polymers of lead (II) [Pb4(O)(L)3(H2O)]n, where H2L = C6H4(CO2H)2 (benzene-1,3-dicarboxylic acid), were synthesized in crystalline (1(a, b)) and amorphous (2(a, b)) phases. Hydrothermal and branch tube methods were used to self-assemble lead (II) from the bottom up to create the crystalline phases. Single-crystal X-ray diffraction (SC-XRD) was used to investigate two crystallized metal-organic frameworks (MOFs) with the same space group and chemical formula (P21/c). Through controlled green sonochemical methods, an ultrasonic bath and a probe homogenizer were used to prepare nano [Pb4(O)(L)3(H2O)]n in the amorphous phase. An extensive study has been conducted on the effect of initial reagent concentration, ultrasonic power, temperature, reaction time, and surfactant presence on the size and morphology of synthesized nanocoordination polymers. Analyses of the synthesized compounds were performed using scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), FT-IR spectroscopy, and CHNS elemental analysis. By using thermal gravimetry (TGA-DTA), the thermal stability of nanostructures was examined and compared with that of crystalline structures. A Hirschfeld surface and a two-dimensional fingerprint diagram were used to analyze intermolecular interactions in crystalline phases. Photocatalytic degradation of methylene blue was investigated using 1a and 2b_2, which represent the synthetic compounds. Calculation of the band gap of synthesized polymers was conducted using the Tauc diagram (based on the DRS results). During optimal conditions of C0 = 0.6 mg L1, pH = 7, and irradiation time = 60 min, the maximum photodegradation efficiencies of methylene blue (MB) were observed for 1a and 2b_2. In terms of degradation efficiency, 1a's reusability was 73.5 % for the first cycle and 70.6 % for the fifth, while 2b_2's reusability was 88.2 % for the first cycle and 81.7 % for the fifth. These materials can be used in multiple photocatalytic cycles based on the results obtained.
Project description:In this manuscript, we have developed an efficient spraying method to successfully fabricate a series of flower-like coordination polymers (CP) microparticles, including Co/BDC (1,4-benzenedicarboxylate) metal organic frameworks (MOF) and infinite coordination polymers (ICP) microparticles, as well as Ni-Co/BDC MOF and Zn/DOBDC (2,5-dioxido-1,4-benzenedicarboxylate) MOF. The spraying method has shown high efficiency and universality in synthesizing the flower-like CP. The crystalline structure can be adjusted by varying the solvent composition in the spraying process. SEM observation demonstrated the MOF and ICP microparticles possess the similar flower-like structure, which is composed of nanoflakes with smooth surface, and the flower-like microparticles could be monodisperse with as low as 5% polydispersity. Moreover, the fabrication of the flower-like CP microparticles by spraying has a wide operation window, because there is no need to precisely control the experiment conditions, like solvents, concentration, and spray order. Due to the practicality of spray technique, this work would pave the way for the manufacture of the flower-like materials and have great potential in applications of catalysis, sensor, energy storage, and so on.
Project description:Crystals of a family of six one-dimensional (1D) coordination polymers of cadmium(II) with cyanopyridines [[CdX2L2] n , where X = Cl, Br, or I and L = 3-cyanopyridine (3-CNpy) or 4-cyanopyridine (4-CNpy)] presented a variety of morphologies and mechanical responses with dominant two-dimensional (2D) anisotropic flexibility, which has not been previously reported. All mechanically adaptable crystals were 2D flexible and displayed a variety of direction-dependent responses; in addition to 2D isotropic flexibility observed for solely elastic materials, 2D anisotropic flexibility was noticed for both elastic and elastic → plastic crystals. The consequences of fine and controlled structural variations on mechanical behavior were additionally explored via microfocus single-crystal X-ray diffraction and complementary theoretical studies, revealing that the relative strength and direction of the hydrogen bonding interactions were the key parameters in delivering a specific mechanical response.
Project description:Inflammatory bowel disease (IBD) is a chronic gastrointestinal disease which is closely related with the overproduced reactive oxygen species (ROS), increased pro-inflammatory cytokines and disordered intestinal microbes. However, current therapeutic methods usually ignored the interrelation among the pathogenesis, and mainly focused on a single factor, inducing clinical outcomes unsatisfied. Herein, biocompatible infinite coordination polymers of drugs (Ce-SASP-RS ICPs) composed of Ce ions, FDA-approved drug sulfasalazine (SASP) and natural ingredient resistant starch (RS) were developed for synergistic treatment of IBD. The proper Ce3+/Ce4+ ratio in Ce-SASP-RS ICPs can endow them with SOD-like activities, POD-like activities and •OH scavenging ability, which guarantee Ce-SASP-RS ICPs to simultaneously kill bacteria and maintain ROS balance through cascade reactions. Owing to the recovered redox balance microenvironment, SASP in Ce-SASP-RS ICPs can better play their anti-inflammatory function. Moreover, benefitting from the recovered metabolic balance of ROS and inflammatory cytokines in colon, resistant starch can also function better in modifying gut microbiota through generating short-chain fatty acids. Collectively, Ce-SASP-RS ICPs can synergistically restore intestinal metabolic microenvironment through modulating redox balance, attenuating inflammation and modifying intestinal flora. Hence, in view of the mutual influences among IBD pathogenesis, this work presents a synergistic intervention approach for effectively treating IBD.