Chunhua Liu

Single-molecule observation of the K+-induced switching of valinomycin within a template network

The K(+)-induced switching of valinomycin has been studied using a molecular template formed by an aromatic oligoamide macrocycle at the liquid/solid interface by scanning tunneling microscopy (STM). Individual valinomycin and its K(+) complex can be identified and resolved in the molecular template, and the high-resolution STM images of valinomycin and its K(+) complex show triangle-like and cyclic structural characteristics, respectively.

On-Surface Observation of the Formation of Organometallic Complex in a Supramolecular Network

The on-surface formation of organometallic monomers or oligomers, especially in supramolecular network, attracts an extensive interest for chemists and material scientist. In this work, we have investigated metal coordination between zinc (II) phthalocyanine (ZnPc) and 1, 3-di (4-pyridyl) propane (dipy-pra) in the 2, 6, 11-tricarboxydecyloxy-3, 7, 10-triundecyloxy triphenylene (asym-TTT) supramolecular template by means of scanning tunneling microscopy (STM) on highly oriented pyrolytic graphite (HOPG) substrate under ambient conditions. The experimental results demonstrate that every two ZnPc molecules in one nano-reactor connect with each other through one dipy-pra molecule by metal-coordination interaction. In this coordinating process, the template of asym-TTT supramolecular networks plays a significant role.

Steric effect on the self-assembly behaviours of amino acid derivatives

To investigate the steric effect of amino acids, N,N′-dialanine-1,4,5,8-naphthalene tetracarboxylic acid diethylamide (ANTA) and N,N′-diphenylalanine-1,4,5,8-naphthalene tetracarboxylic acid diethylamide (PNTA) were synthesized based on naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTA) with alanine and phenylalanine, respectively. These compounds were characterized by infrared spectroscopy (IR), magnetic resonance spectroscopy (1H NMR, 13C NMR) and mass spectrometry (MS). Interestingly, ANTA could self-assemble into spiral nanorings, but PNTA formed nanospheres. In order to reveal the self-assembly driving forces, the two-dimensional (2D) supramolecular self-assembly behaviours were studied on highly oriented pyrolytic graphite (HOPG) by scanning tunneling microscopy (STM) at the solid–liquid interface, which indicated the driving forces could be attributed to intermolecular hydrogen-bonding and π–π stacking interactions. These results represent different self-assembly behaviours due to the steric effect of amino acids.

Nano-film pesticide for Schistosoma japonicum cercariae: synthesis, characterization, toxicity and insecticidal effect

To improve the efficiency of pesticides, two novel niclosamide derivatives have been synthesized by adding polyethylene glycol groups (PEG) with different lengths to the niclosamide core. The derivatives were characterized by infrared spectroscopy (IR) and magnetic resonance (1H NMR). The results from brewster angle microscopy (BAM) revealed that these two derivatives formed a self-diffusion thin film at the air–water interface. In addition, Langmuir–Blodgett (LB) films on solid substrate have been used to investigate the formation mechanism of the thin film at the air–water interface, combined with atomic force microscopy (AFM). It was suggested that the height of the monolayer at the air–water interface is consistent with the theoretical length of niclosamide derivatives. Further experimental results indicated that these two compounds exhibit relatively low cytotoxicity to HeLa cells, but have higher efficiency to anti-cercariae compared with that of pristine pesticide.

Supramolecular three-component amino acid-based hydrogels with superior mechanical strength for controllably promoting nonpathogenic E. coli growth

Novel three-component hybrid hydrogels have been constructed by amino acid derivatives, riboflavin and melamine through self-assembly. In the process of gelation, the driving forces are attributed to hydrogen bonding and π–π interaction. These luminescent hydrogels demonstrate excellent mechanical strength (>104 Pa) and low cell toxicity, which have been investigated by means of ultraviolet spectra (UV), fluorescence spectra, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), rheological experiments and cytotoxicity assay. Whats more, these hybrid hydrogels could be used to drive the drug release in a controlled manner and be used for promoting E. coli growth, and they accelerate the growth of E. coli distinctly.

Asymmetry-Induced Supramolecular Helices of Pyrene-Perylene Bisimide Triads

The formation of helical nanostructure is investigated for donor/acceptor system. The helices of the supramolecular nanofibres can be revealed by atom force microscope (AFM) and circular dichroism (CD) measurement. The expermental results show the Py-Per-Py can self assembly into helical nanofibres. The controlled experiments on the compound Py-e-Per-e-Py with symmetrical conformation indicates the formation of helical nanofibres may be attributed to asymmetrical conformation.

Controllable Fabrication of Layer Structures by Self-Assembled Perylene Derivative

The compound of perylene-3,4,9,10-tetracarboxylic acid (PTCA) has been synthesized and characterized. By varying the concentration, it can be used to modulate the supramolecular self-assembly morphologies. Atom force microscopy (AFM) images show that the nano-layer structure will be obtained in relatively high concentration. This structure mainly depends on the intermolecular hydrogen-bonding and π–π stacking interactions.