Diversity-oriented synthesis and antifungal activities of novel pimprinine derivative bearing a 1,3,4-oxadiazole-5-thioether moiety.

Based on the strategy of diversity-oriented synthesis and the structures of natural product pimprinine and streptochlorin, two series of novel pimprinine derivatives containing 1,3,4-oxadiazole-5-thioether moieties were efficiently synthesized under the optimized reaction conditions. Biological assays conducted at Syngenta showed the designed derivatives displayed an altered pattern of biological activity, of which 5h was identified as the most promising compound with strong activity against Pythium dissimile and also a broad antifungal spectrum in primary screening. Further structural optimization of pimprinine and streptochlorin derivatives is well under way, aiming to discover synthetic analogues with improved antifungal activity. Two series of novel pimprinine derivatives containing 1,3,4-oxadiazole-5-thioether moieties were efficiently synthesized through diversity-oriented synthesis strategy under the optimized conditions. Biological assays showed the designed derivatives exhibited potential activity.

N-(2-Aminoethyl)-2-(hexylthio) Acetamide-Functionalized Pillar[5]arene for the Selective Detection of l-Trp through Guest-Adaptive Multisupramolecular Interactions.

Tryptophan (Trp) is very necessary for biosystems; therefore, high-efficient detection of Trp is an important subject. Hereof, based on our early research works on fluorescent sensors, we rationally designed and synthesized a fluorescent sensor (SNP5) based on N-(2-aminoethyl)-2-(hexylthio) acetamide-functionalized pillar[5]arene, which showed high selectivity and sensitive recognition for l-Trp (LOD = 2.19 × 10-8 M). Moreover, SNP5 exhibited aggregation-induced emission enhancement fluorescence. Within SNP5, the pillar[5]arene group could act as N-H···π- and C-H···π-interaction sites, as well as a H-bond-interaction site; meanwhile, the N-(2-aminoethyl)-2-(hexylthio) acetamide group also served as a multihydrogen-bonding site. As a result, SNP5 could selectively detect l-Trp through the synergy of the pillar[5]arene group and the N-(2-aminoethyl)-2-(hexylthio) acetamide group. Compared with previous work, the results of this work support the strategy that changing the functionalized group of the pillar[5]arene can adjust the selectivity of the pillar[5]arene-based sensor and achieve the detection of different amino acids. The detection mechanism was specifically researched through experiments and theoretical calculations including frontier orbitals, electrostatic potential, and the independent gradient model approach. Interestingly, these theoretical calculations not only supported the experimental results but also provided a visualized understanding of guest-adaptive multisupramolecular interactions between SNP5 and l-Trp.

Tailoring an HSO4- anion hybrid receptor based on a phenazine derivative.

A catechol-functionalized phenazine imidazole (PD) was tailored with 2,3-diaminophenazine and 3,4-dihydroxy benzaldehyde, and it served as a hybrid acceptor for capturing HSO4- anions. The selectivity and sensitivity of the PD receptor for anion sensing were studied. It was found that the PD receptor could not only display a preferable sensitivity to HSO4- ions with a "turn-off" fluorescence response, but also have a strong anti-interference ability toward other common anions, especially basic anions such as CH3COO-, HPO42-, and H2PO4-. The anion recognition mechanism of PD towards HSO4- is based on multiple hydrogen bond interactions. Finally, the strips for anion detection were prepared, which were verified to be a convenient and high-efficiency test kit for detecting HSO4- ions with the naked eye.

A pillar[5]arene-based fluorescent sensor for sensitive detection of L-Met through a dual-site collaborative mechanism.

L-Methionine (L-Met) is one of the essential amino acids in human health, efficiently detect L-Met is a significant issue. Herein, a concept "dual-site collaborative recognition" had been successfully introduced into the design and achieved high selective and sensitive recognition of L-Met. In order to realize the "dual-site collaborative recognition", we rationally designed and synthesized an ester functionalized pillar[5]arene-based fluorescent sensor (SP5). And it shows blue Aggregation-induced emission (AIE) fluorescence. In the SP5, the pillar[5]arene group act as C-H···π interactions site, and ester group serve as multi hydrogen bonding acceptor. Interestingly, the SP5 exhibited high selectivity and sensitivity (2.84 × 10-8 M) towards L-Met based on the collaboration of electron-rich cavernous pillar[5]arene group and ester group through C-H···π and H-bond interactions, respectively. This "dual-site collaborative recognition" mechanism has been investigated by 1H NMR, ESI-MS and theoretical calculation including frontier orbital (HOMO and LUMO), electrostatic potential (ESP) and the noncovalent interaction (NCI). These theoretical calculations not only support the proposed host-guest recognition mechanism, but also provided visualized information on the "dual-site collaborative recognition" mode. Furthermore, the concept "dual-site collaborative recognition" is an effective strategy for easily detecting biological molecules.

Aggregation-induced emission supramolecular organic framework (AIE SOF) gels constructed from tri-pillar[5]arene-based foldamer for ultrasensitive detection and separation of multi-analytes.

In this study, a novel aggregation-induced emission supramolecular organic framework (AIE SOF) with ultrasensitive response, termed FSOF, was constructed using a tri-pillar[5]arene-based foldamer. Interestingly, benefiting from the noise signal shielding properties of FSOF as well as the competition between the cationπ and ππ interactions, the FSOF shows an ultrasensitive response for multi-analytes, such as Fe3+, Hg2+ and Cr3+. The limits of detection (LODs) of the FSOF for Fe3+, Hg2+ and Cr3+ are in the range of 9.40 × 10-10-1.86 × 10-9. More importantly, the xerogel of FSOF exhibits porous mesh structures, which could effect high-efficiency separation above metal ions from their aqueous solution, with adsorption percentages in the range 92.39-99.99%. In addition, by introducing metal ions into the FSOF, a series of metal ions coordinated supramolecular organic frameworks (MSOFs) were successfully constructed. Moreover, MSOFs show selective fluorescence "turn on" ultrasensitive detection CN- (LOD = 2.12 × 10-9) and H2PO4- (LOD = 1.78 × 10-9). This is a novel approach to construct SOFs through a tri-pillar[5]arene-based foldamer, and also provides a new way to achieve ultrasensitive detection and high-efficiency separation.