A pillared framework formed from 4,4'-bipyridine (bipy) and sheets of dinuclear Cd(2) nodes and 1,4-benzenedicarboxylic acid (bdc) linkers can be prepared in both interpenetrated and noninterpenetrated forms by simply varying the temperature or concentration of the reaction. These results demonstrate that higher temperatures and concentrations favor interpenetration over the corresponding noninterpenetrating structure, an observation that could have broad implications for controlling the synthesis of metal-organic materials.
Hydrogen peroxide (H 2 O 2 ) is a mild but versatile oxidizing agent with extensive applications in bleaching, wastewater purification, medical treatment, and chemical synthesis. The state-of-art H 2 O 2 production via anthraquinone oxidation is hardly considered a cost-efficient and environment-friendly process because it requires high energy input and generates hazardous organic wastes. Photocatalytic H 2 O 2 production is a green, sustainable, and inexpensive process which only needs water and gaseous dioxygen as the raw materials and sunlight as the power source. Inorganic metal oxide semiconductors are good candidates for photocatalytic H 2 O 2 production due to their abundance in nature, biocompatibility, exceptional stability, and low cost. Progress has been made to enhance the photocatalytic activity toward H 2 O 2 production, however, H 2 O 2 photosynthesis is still in the laboratory research phase since the productivity is far from satisfaction. To inspire innovative ideas for boosting the H 2 O 2 yield in photocatalysis, the most well-studied metal oxide photocatalysts are selected and the modification strategies to improve their activity are listed. The mechanisms for H 2 O 2 production over modified photocatalysts are discussed to highlight the facilitating role of the modification methods. Besides, methods for the quantification of H 2 O 2 and associated radical intermediates are provided to guide future studies in this field.
The isolation and structure elucidation of six new bacterial metabolites [spoxazomicin D (2), oxachelins B and C (4, 5), and carboxamides 6–8] and 11 previously reported bacterial metabolites (1, 3, 9–12a, and 14–18) from Streptomyces sp. RM-14-6 is reported. Structures were elucidated on the basis of comprehensive 1D and 2D NMR and mass spectrometry data analysis, along with direct comparison to synthetic standards for 2, 11, and 12a,b. Complete 2D NMR assignments for the known metabolites lenoremycin (9) and lenoremycin sodium salt (10) were also provided for the first time. Comparative analysis also provided the basis for structural revision of several previously reported putative aziridine-containing compounds [exemplified by madurastatins A1, B1, C1 (also known as MBJ-0034), and MBJ-0035] as phenol-dihydrooxazoles. Bioactivity analysis [including antibacterial, antifungal, cancer cell line cytotoxicity, unfolded protein response (UPR) modulation, and EtOH damage neuroprotection] revealed 2 and 5 as potent neuroprotectives and lenoremycin (9) and its sodium salt (10) as potent UPR modulators, highlighting new functions for phenol-oxazolines/salicylates and polyether pharmacophores.
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