Degradable Organically-Derivatized Polyoxometalate with Enhanced Activity against Glioblastoma Cell Line

High efficacy and low toxicity are critical for cancer treatment. Polyoxometalates (POMs) have been reported as potential candidates for cancer therapy. On accounts of the slow clearance of POMs, leading to long-term toxicity, the clinical application of POMs in cancer treatment is restricted. To address this problem, a degradable organoimido derivative of hexamolybdate is developed by modifying it with a cleavable organic group, leading to its degradation. Of note, this derivative exhibits favourable pharmacodynamics towards human malignant glioma cell (U251), the ability to penetrate across blood brain barrier and low toxicity towards rat pheochromocytoma cell (PC12). This line of research develops an effective POM-based agent for glioblastoma inhibition and will pave a new way to construct degradable anticancer agents for clinical cancer therapy.

Label-free colorimetric detection of mercury via Hg(2+) ions-accelerated structural transformation of nanoscale metal-oxo clusters

Mercury and its compounds are known to be extremely toxic but widely distributed in environment. Although many works have been reported to efficiently detect mercury, development of simple and convenient sensors is still longed for quick analyzing mercury in water. In this work, a nanoscale metal-oxo cluster, (n-Bu4N)2[Mo5NaO13(OCH3)4(NO)], (MLPOM), organically-derivatized from monolacunary Lindqvist-type polyoxomolybdate, is found to specifically react with Hg(2+) in methanol/water via structural transformation. The MLPOM methanol solution displays a color change from purple to brown within seconds after being mixed with an aqueous solution containing Hg(2+). By comparing the structure of polyoxomolybdate before and after reaction, the color change is revealed to be the essentially structural transformation of MLPOM accelerated by Hg(2+). Based on this discovery, MLPOM could be utilized as a colorimetric sensor to sense the existence of Hg(2+), and a simple and label-free method is developed to selectively detect aqueous Hg(2+). Furthermore, the colorimetric sensor has been applied to indicating mercury contamination in industrial sewage.

A simple synthetic route to polyoxovanadate-based organic–inorganic hybrids using EEDQ as an ester coupling agent

A simple synthetic strategy for the post-functionalization of organically derivatized hexavanadates is presented.

Diversified polyoxovanadate derivatives obtained by copper(i)-catalysed azide-alkyne cycloaddition reaction: their synthesis and structural characterization

In this work, we confirmed that the copper-catalysed azide-alkyne cycloaddition (CuAAC) reaction is an effective method for the organic-functionalization of polyoxometalates (POMs). Herein, for the first time, four novel 1,2,3-triazole functionalized polyoxovanadate (POV) organic-inorganic hybrids, (Bu4N)2[V6O13{(OCH2)3C5H6N3O}2]·1.5CH3CN 2, (Bu4N)2[V6O13{(OCH2)3C7H8N3O2}2]·2CH3CN 3, (Bu4N)2[V6O13{(OCH2)3C11H10N3}2] 4 and (Bu4N)2[V6O13{(OCH2)3C10H7N3Cl}2] 5 were prepared through the CuAAC reaction using the azide functionalized hexavanadate, (Bu4N)2[V6O13{(OCH2)3CCH2N3}2]·2.5CH3CN 1, as the precursor, where CuI was used as the catalyst and N,N-diisopropylethylamine (DIPEA) as a stabilizer for CuI. All the four compounds were structurally and compositionally characterized by single-crystal X-ray diffraction, elemental analyses, powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), 1H NMR, ESI-MS, UV-Vis and thermogravimetric analysis (TGA).

Tosylation of alcohols: an effective strategy for the functional group transformation of organic derivatives of polyoxometalates

Recently, the organic functionalization of polyoxometalates (POMs) has drawn increasing interest, and an easy and effective route to achieve organic derivatives is of great importance. Herein, the first reported synthesis of a tosyl ester derivative of the polyoxometalate (Bu4N)2[V6O13{(OCH2)3CCH2SO3C7H4}2]·2.5CH3CN (compound 1) was performed by using DMAP as an activating reagent and triethylamine as an HCl scavenger. The tosyl ester was transformed into an azide or halide group by using sodium azide or sodium bromide, respectively, as the nucleophilic agent. Two derivatives of POMs, (Bu4N)2[V6O13{(OCH2)3CCH2N3}2]·4CH3CN (compound 2) and (Bu4N)2[V6O13{(OCH2)3CCH2Br}2] (compound 3), were easily obtained. All the compounds were structurally and compositionally characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, NMR spectroscopy, ESI-MS, UV-Vis spectroscopy and TGA. This work provides a new route for the functional group transformation of organic derivatives of polyoxometalates.

Brain substrates of perceived spatial separation between speech sources under simulated reverberant listening conditions in schizophrenia

BACKGROUND

People with schizophrenia recognize speech poorly under multiple-people-talking (informational masking) conditions. In reverberant environments, direct-wave signals from a speech source are perceptually integrated with the source reflections (the precedence effect), forming perceived spatial separation (PSS) between different sources and consequently improving target-speech recognition against informational masking. However, the brain substrates underlying the schizophrenia-related vulnerability to informational masking and whether schizophrenia affects the unmasking effect of PSS are largely unknown.

METHOD

Using psychoacoustic testing and functional magnetic resonance imaging, respectively, the speech recognition under either the PSS or perceived spatial co-location (PSC) condition and the underlying brain substrates were examined in 20 patients with schizophrenia and 16 healthy controls.

RESULTS

Speech recognition was worse in patients than controls. Under the PSS (but not PSC) condition, speech recognition was correlated with activation of the superior parietal lobule (SPL), and target speech-induced activation of the SPL, precuneus, middle cingulate cortex and caudate significantly declined in patients. Moreover, the separation (PSS)-against-co-location (PSC) contrast revealed (1) activation of the SPL, precuneus and anterior cingulate cortex in controls, (2) suppression of the SPL and precuneus in patients, (3) activation of the pars triangularis of the inferior frontal gyrus and middle frontal gyrus in both controls and patients, (4) activation of the medial superior frontal gyrus in patients, and (5) impaired functional connectivity of the SPL in patients.

CONCLUSIONS

Introducing the PSS listening condition efficiently reveals both the brain substrates underlying schizophrenia-related speech-recognition deficits against informational masking and the schizophrenia-related neural compensatory strategy for impaired SPL functions.

4-[(1H-imidazol-4-yl) methyl] benzamidines and benzylamidines: novel antagonists of the histamine H3 receptor

A series of amidine substituted phenyl-, benzyl-, and phenethylimidazoles based on the known H3 agonist SK&F 91606 (4) has been synthesized and tested as ligands for the histamine H3 receptor. Insertion of a phenyl ring between the imidazole ring and the amidine moiety produces antagonists. The benzyl series was found to be the most potent and was further investigated. Compounds 9c and 18 (entries 5 and 12, Table 1) are potent ligands for the H3 receptor with K(i) values of 16 nM and 7.2 nM respectively. In vivo, both compounds were shown to be equipotent to thioperamide (2), the standard H3 antagonist.

A Series of Weakley-type Polyoxomolybdates: Synthesis, Characterization, and Magnetic Properties by a Combined Experimental and Theoretical Approach

Using DCC as the dehydrating agent, a series of Weakley-type polyoxomolybdates [Bu₄N]₃{Ln[Mo₅O₁₃(OMe)₄(NO)]₂} (Ln = Tb, Dy, Ho, Er) were synthesized in a one-pot reaction and structurally characterized by elemental, IR, UV-vis analysis, PXRD, and single-crystal X-ray diffraction. Furthermore, the static and dynamic measurements were utilized to investigate their magnetic performances. Typically, slow relaxation of magnetization was observed for Dy analogues with an energy barrier for the reversal of the magnetization of 50 K, which is the highest barrier height observed on the polyoxomolybdates-based single-molecule magnets (SMMs). For a deep understanding of the appearance of the SMM behavior on Weakley-type polyoxomolybdates series, ab initio calculations on {Dy[Mo₅O₁₃(OMe)₄(NO)]₂}^3- have been conducted.

Brain substrates underlying auditory speech priming in healthy listeners and listeners with schizophrenia

BACKGROUND

Under 'cocktail party' listening conditions, healthy listeners and listeners with schizophrenia can use temporally pre-presented auditory speech-priming (ASP) stimuli to improve target-speech recognition, even though listeners with schizophrenia are more vulnerable to informational speech masking.

METHOD

Using functional magnetic resonance imaging, this study searched for both brain substrates underlying the unmasking effect of ASP in 16 healthy controls and 22 patients with schizophrenia, and brain substrates underlying schizophrenia-related speech-recognition deficits under speech-masking conditions.

RESULTS

In both controls and patients, introducing the ASP condition (against the auditory non-speech-priming condition) not only activated the left superior temporal gyrus (STG) and left posterior middle temporal gyrus (pMTG), but also enhanced functional connectivity of the left STG/pMTG with the left caudate. It also enhanced functional connectivity of the left STG/pMTG with the left pars triangularis of the inferior frontal gyrus (TriIFG) in controls and that with the left Rolandic operculum in patients. The strength of functional connectivity between the left STG and left TriIFG was correlated with target-speech recognition under the speech-masking condition in both controls and patients, but reduced in patients.

CONCLUSIONS

The left STG/pMTG and their ASP-related functional connectivity with both the left caudate and some frontal regions (the left TriIFG in healthy listeners and the left Rolandic operculum in listeners with schizophrenia) are involved in the unmasking effect of ASP, possibly through facilitating the following processes: masker-signal inhibition, target-speech encoding, and speech production. The schizophrenia-related reduction of functional connectivity between the left STG and left TriIFG augments the vulnerability of speech recognition to speech masking.

Peptide sequence mediated self-assembly of molybdenum blue nanowheel superstructures

The precise control over the formation of complex nanostructures, e.g. polyoxometalates (POMs), at the sub-nanoscale is challenging but critical if non-covalent architectures are to be designed. Combining biologically-evolved systems with inorganic nanostructures could lead to sequence-mediated assembly. Herein, we exploit oligopeptides as multidentate structure-directing ligands via metal-coordination and hydrogen bonded interactions to modulate the self-assembly of POM superstructures. Six oligopeptides (GH, AH, SH, G2H, G4H and G5H) are incorporated into the cavities of Molybdenum Blue (MB) POM nanowheels. It is found that the helicity of the nanowheel can be readily switched (Δ to Λ) by simply altering the N-terminal amino acid on the peptide chain rather than their overall stereochemistry. We also reveal a delicate balance between the Mo-coordination and the hydrogen bonds found within the internal cavity of the inorganic nanowheels which results in the sequence mediated formation of two unprecedented asymmetrical nanowheel frameworks: {Mo122Ce5} and {Mo126Ce4}.

Unprecedented Halide-Ion Binding and Catalytic Activity of Nanoscale Anionic Metal Oxide Clusters

One halide ion (X^- ) can bind on the surface of nanoscale Anderson-type polyoxometalate (POMs) clusters [(n-C₄ H₉ )₄ N]₃ {AlMo₆ O₁₈ (OH)₃ [(OCH₂ )₃ CCH₃ ]}, and form stable complexes in solution with binding constant K=1.53×10³ . Single-crystal structural analysis showed that this binding behavior occurs through multiple hydrogen bonding between X^- and three hydroxy groups on the uncapped side of the cluster. This supramolecular interaction in the cluster systems means that their catalytic activities, evaluated from the oxidation of alcohols to aldehydes, can be switched upon the introduction of halide ions and water molecules. The halide ions work as inhibitors by blocking the active sites of the clusters while they can be re-activated by the addition of water.

Correction: Diversified polyoxovanadate derivatives obtained by copper(i)-catalysed azide-alkyne cycloaddition reaction: their synthesis and structural characterization

Correction for 'Diversified polyoxovanadate derivatives obtained by copper(i)-catalysed azide-alkyne cycloaddition reaction: their synthesis and structural characterization' by Hongli Jia et al., Dalton Trans., 2018, 47, 577-584.