The Influence of Light-Generated Radicals for Highly Efficient Solar-Thermal Conversion in an Ultra-Stable 2D Metal-Organic Assembly.

Solar-thermal water evaporation is a promising strategy for clean water production, which needs the development of solar-thermal conversion materials with both high efficiency and high stability. Herein, we reported an ultra-stable cobalt(II)-organic assembly NKU-123 with light-generated radicals, exhibiting superior photothermal conversion efficiency and high stability. Under the irradiation of 808 nm light, the temperature of NKU-123 rapidly increases from 25.5 to 215.1 °C in 6 seconds. The solar water evaporator based on NKU-123 achieves a high solar-thermal water evaporation rate of 1.442 and 1.299 kg m-2 h-1 under 1-sun irradiation with a water evaporation efficiency of 97.8 and 87.9 % for pure water and seawater, respectively. A detailed mechanism study revealed that the formation of light-generated radicals leads to an increase of spin density of NKU-123 for enhancing the photothermal effect, which provides insights into the design of highly efficient photothermal materials.

The influence of light on the field-induced magnetization dynamics of two Er(III) coordination polymers with different halogen substituents.

Photocontrolled magnetic properties are fundamental for the applications of molecular magnets, which have the features of high time and space resolution; however, such magnetic properties are highly challenging to be achieved owing to the weak light-matter interactions. Herein, the influence of in situ light irradiation on the field-induced magnetization dynamics of two Er(III) coordination polymers 1 and 2 with the same coordination skeletons but different halogen substituents was studied. 1 and 2, and their in situ photoexcited products 1a and 2a, display field-induced magnetization dynamics based on Orbach and/or Raman processes. The magnetization dynamics are fine-modulated by the synergetic effect of light irradiation and a ligand substituent, due to the charge re-distribution of the excited states of the ligand.

Modulation of magnetization dynamics of an Er(III) coordination polymer by the conversion of a ligand to a radical using UV light.

Light-induced substance conversion is highly promising for creating new radical-based compounds. Herein, we report an Er(III) coordination polymer [Er(CA)(ACA)(DMF)(H2O)]n (1) and its Y(III)-diluted analogue 1@Y (H2CA = 2,5-dichloro-3,6-dihydroxy-p-quinone, HACA = 9-anthracene carboxylic acid) with the light-induced transformation of the ligand to a radical. The χMT values of light-transformed products 1a and 1a@Y are higher than those of 1 and 1@Y, respectively, due to the formation of radicals by ultraviolet light irradiation, confirmed by EPR measurement as well. The effective energy barriers for magnetization reversal (Ueff) decrease from 72 K for 1 to 67 K for 1a, and from 117 K for 1@Y to 94 K for 1a@Y. This work not only provides a new light-conversion system but also reveals the nature of photo-induced variation of magnetic properties.

Alkyl Chains Modulated Magnetization Dynamics of Mononuclear Trigonal Prismatic CoII Complexes.

Four benzeneboron-capped mononuclear CoII complexes with different alkyl substitutions on the fourth position of phenylboronic acid were obtained. The CoII ions are all wrapped by the pocket-like ligands and located in trigonal prismatic coordination geometries. Alternating-current magnetic susceptibility measurements reveal that they show different magnetization dynamics, such as distinct relaxation rates at the same temperature, the faster QTM rates for the ethyl and propyl substituted complexes, as well as different relaxation processes. Magneto-structural correlation study reveals that the various deviations of coordination geometry of CoII ion, diverse crystal packings and possible different vibration modes of substituents caused by modifying alkyl chains are the key factors affecting the magnetization dynamics. This work demonstrates that the alkyl chains even locating far away from the metal center can have a large impact on the magnetic behavior of the CoII complex with a very rigid coordination geometry, offering a new perspective towards transition metal based single-molecule magnets.

New diketopiperazine alkaloid and polyketides from marine-derived fungus Penicillium sp. TW58-16 with antibacterial activity against Helicobacter pylori.

Marine-derived fungi can usually produce structurally novel and biologically potent metabolites. In this study, a new diketopiperazine alkaloid (1) and two new polyketides (10 and 11), along with 8 known diketopiperazine alkaloids (2-9) were isolated from marine-derived fungus Penicillium sp. TW58-16. Their structures were fully elucidated by analyzing UV, IR, HR-ESI-MS, 1D, and 2D NMR spectroscopic data. The absolute configurations of the new compounds 1, 10 and 11 were ascertained by X-ray diffraction (Cu Kα radiation) and comparing their CD data with those reported. In addition, the antibacterial activities of these compounds against Helicobacter pylori in vitro were assessed. Results showed that compounds 3, 6, 8 and 9 displayed moderate antibacterial activity against standard strains and drug-resistant clinical isolates of H. pylori in vitro. This result demonstrates that diketopiperazine alkaloids could be lead compounds to be explored for the treatment of H. pylori infection.

New Drimane Sesquiterpenes and Polyketides from Marine-Derived Fungus Penicillium sp. TW58-16 and Their Anti-Inflammatory and α-Glucosidase Inhibitory Effects.

Marine fungi-derived natural products represent an excellent reservoir for the discovery of novel lead compounds with biological activities. Here, we report the identification of two new drimane sesquiterpenes (1 and 2) and six new polyketides (3-8), together with 10 known compounds (9-18), from a marine-derived fungus Penicillium sp. TW58-16. The planar structures of these compounds were elucidated by extensive 1D and 2D NMR, which was supported by HR-ESI-MS data. The absolute configurations of these compounds were determined by experimental and calculated electronic circular dichroism (ECD), and their optical rotations compared with those reported. Evaluation of the anti-inflammatory activity of compounds 1-18 revealed that compound 5 significantly inhibited the release of nitric oxide (NO) induced by lipopolysaccharide (LPS) in RAW264.7 cells, correlating with the inhibition of expression of inducible nitric oxide synthase (iNOS). In addition, we revealed that compounds 1, 3-6, 14, 16, and 18 showed strong α-glucosidase inhibitory effects with inhibition rates of 35.4%, 73.2%, 55.6%, 74.4%, 32.0%, 36.9%, 88.0%, and 91.1%, respectively, which were comparable with or even better than that of the positive control, acarbose. Together, our results illustrate the potential of discovering new marine-based therapeutic agents against inflammation and diabetes mellitus.

Enhancing the energy barrier and hysteresis temperature in two benchtop-stable Ho(iii) single-ion magnets.

The energy barrier and hysteresis temperature in two benchtop-stable D5h-symmetry HoIII single-ion magnets were significantly enhanced via the variation of the halogen anion. The coexistence of a high energy barrier of 418 K and hysteresis temperature of 15 K was observed in the bromide-ion containing HoIII single-ion magnet.

New pyrones and their analogs from the marine mangrove-derived Aspergillus sp. DM94 with antibacterial activity against Helicobacter pylori.

Marine fungi are well known for their ability to produce a multitude of natural products and have been proved to be a particularly rich source of drug leads. Here, 20 pyrones and their analogs (1-20), including two new compounds (1 and 6), were obtained from a marine-derived fungus strain of Aspergillus sp. DM94. Their structures were determined by analyses of UV, IR, HR-ESI-MS, and NMR data. The ability to inhibit Helicobacter pylori in vitro was assessed for these isolated compounds. Results showed that the bis-naphtho-γ-pyrones exhibited potent antibacterial activity against both the standard and multidrug-resistant H. pylori strains. Structure-activity relationship (SAR) analysis suggested that the bis-naphtho[2,3-b]pyrones showed better anti-H. pylori activity than a hybrid of naphtho[2,3-b]pyrone and naphtho[1,2-b]pyrone. In addition, the free hydroxyl group of the C-8 position in the lower unit is vital for its anti-H. pylori activity. Importantly, compound 18 showed a synergistic effect in combination with amoxicillin, clarithromycin, or metronidazole, suggesting its potential use to overcome antibiotic resistance of H. pylori. This study shed light on the discovery of new anti-H. pylori agents. KEY POINTS: • New pyrones discovered from a marine-derived fungus Aspergillus sp. DM94. • Bis-naphtho-γ-pyrones showed potent anti-H. pylori activity. • The anti-H. pylori SAR analysis of bis-naphtho-γ-pyrones was discussed. • Bis-naphtho-γ-pyrone 18 showed synergistic effect with clinical antibiotics.

Single-chain magnets assembled in cobalt(ii) metal-organic frameworks.

Single-chain magnets (SCMs) are one-dimensional (1D) coordination polymers that exhibit magnetic bistability and have potential application in high-density information processing. Usually SCMs are magnetically isolated chains stacked by hydrogen bonds or ππ stacking; however, with the rapid development of metal-organic frameworks (MOFs), coordination chains assembled in MOFs have also shown SCM behaviour when the 1D magnetic correlation is strong enough in comparison to the other two dimensionalities. The high-dimensional framework of MOFs could also help in the formation of coordination chains that cannot form in isolated one-dimensional coordination systems. This feature article highlights the progress in this field by summarizing cobalt(ii)-based MOFs exhibiting SCM behaviour and classifying them into categories according to the bridging ligands within the CoII chains, to provide fundamentals for further studies on the magnetic properties of coordination chains assembled in MOFs.

Synthesis, Characterization, Thermal Stability and Sensitivity Properties of New Energetic Polymers-PVTNP-g-GAPs Crosslinked Polymers.

A series of energetic polymers, poly(vinyl 2,4,6-trinitrophenylacetal)-g-polyglycidylazides (PVTNP-g-GAPs), were synthesized via cross-linking reactions of PVTNP with three different molecular weight GAPs using toluene diisocyanate as the cross-linking agent. The structures of these energetic polymers were characterized by ultraviolet visible spectra (UV⁻Vis), attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR-FTIR), and nuclear magnetic resonance spectrometry (NMR). The glass-transition temperatures of these energetic polymers were measured with differential scanning calorimetry (DSC) method, and the results showed that all the measured energetic polymers have two distinct glass-transition temperatures. The thermal decomposition behaviors of these energetic polymers were evaluated by differential thermal analysis (DTA), thermogravimetric analysis (TGA) and thermogravimetric analysis tandem infrared spectrum (TGA-IR). The results indicated that all the measured energetic polymers have excellent resistance to thermal decomposition up to 200 °C, and the initial thermal decomposition was attributed to the breakdown of azide group. Moreover, the sensitivity properties of these energetic polymers were measured with the national military standard methods and their compatibilities with the main energetic components of 2,4,6-trinitrotoluene (TNT)-based melt-cast explosive were evaluated by using the DTA method. The results indicate that these energetic polymers have feasible mechanical sensitivities and can be safely used with TNT, cyclotetramethylene tetranitramine (HMX), 1,1-diamino-2,2-dinitroethene (FOX-7), 3-nitro-1,2,4-triazol-5-one (NTO) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB).