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AuCl(PMe 3 ) and AuCl(PEt 3 ) were used to react with quinoline-8-thiolate (8-QNS) to give three Au(I) complexes, i.e., [8-QNS(AuPMe 3 ) 2 ]ClO 4 ( 1 ), [(8-QNS) 2 Ag(AuPMe 3 ) 2 ]ClO 4 ( 2 ), and [8-QNS(AuPEt 3 ) 2 ]ClO 4 ( 3 ), which have been structurally determined by X-ray diffraction to show various intra- and intermolecular metal···metal contacts (i.e., metal = Au(I) or Ag(I)). All complexes displayed solid-state luminescence at 535-568 nm, which is most likely attributed to an intraligand transition of 8-QNS and/or a S → Au(I) charge-transfer transition, possibly modified by Au(I)···Au(I) interactions. Notably, complex 1 ·CH 2 Cl 2 exhibited remarkable mechanochromic luminescence from 535 to 601 nm upon grinding. While immersed in various solvents for the ground powder samples of complex 1 ·CH 2 Cl 2 , the luminescence at 601 nm mostly reverted to the original luminescence. Powder X-ray diffraction measurements indicated that complex 1 ·CH 2 Cl 2 underwent structural transformation from a crystalline to an amorphous phase upon grinding, and it can be restored to the original crystalline phase upon immersion in various solvents. Additionally, the reversible experiments of complex 1 ·CH 2 Cl 2 for the grinding and immersion actions were performed for up to five cycles. Moreover, the time-dependent luminescence spectra for the crystalline samples of complex 1 ·CH 2 Cl 2 were measured, and they showed a significant luminescence change from 535 to 590 nm within 2 days.

Three supramolecular architectures, [Cu 2 (dpds) 2 (C 5 O 5 ) 2 (H 2 O) 4 ]·3H 2 O ( 1 ), [Cu(dpds)(C 5 O 5 )]·3H 2 O ( 2 ), and [Cu 2 (dpds) 2 (C 5 O 5 ) 2 ]·9H 2 O·C 2 H 5 OH ( 3 ) (dpds = 4,4'-dipyridyldisulfide and C 5 O 5 2- (croconate) = dianion of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione), have been synthesized and structurally characterized. Compound 1 contains two crystallographically independent Cu(II) ions, which are both distorted octahedral geometry with elongation along the croconate- and H 2 O-bound axial positions and bonded with two N atoms of two dpds, two O atoms of one C 5 O 5 2- , and two H 2 O molecules. Two crystallographically independent dpds ligands, both adopting the bis-monodentate bridging mode, connect two Cu(II) ions to form a one-dimensional zigzag chain-like coordination polymer. In 2 and 3 , there are two and three crystallographically independent Cu(II) ions, respectively, which are all distorted octahedral geometries with elongation along the croconate-bound axial positions six-coordinated and bonded with two N atoms of two dpds ligands in cis- or/and trans-forms and four O atoms of two C 5 O 5 2- ligands. The dpds ligands in 2 and 3 all adopt the bis-monodentate bridging mode, and the C 5 O 5 2- ligands act as bridging ligands with bridging bis-bidentate through three C 5 O 5 2- oxygen atoms in 2 and bridging bis-bidentate through four adjacent C 5 O 5 2- oxygen atoms in 3 , respectively, linking the Cu(II) ions to generate a two-dimensional layered and a three-dimensional metal-organic framework, respectively. The structural diversity and dimensionality observed in 1 - 3 may be attributed to the cis- or/and trans-coordination sphere of Cu(II) centers with two dpds ligands and the coordination modes of croconate ligands. Thermal stability and in situ temperature-dependent structural variations of 1 - 3 have been verified by thermogravimetric analysis and powder X-ray diffraction measurements. Compounds 1 and 3 both exhibit water vapor capture behaviors with hysteresis isotherms., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

In this study, we synthesized a new Co(II) complex, [NMe 4 ] 2 [Co(bpyO 2 ) 2 ] ( 1 ), using deprotonated 2,2'-bipyridine-6,6'-diol ligands (bpyO 2 2- ). This compound exhibits a significant zero-field splitting ( D ) value. The far-infrared magneto spectroscopy and high-frequency and field electron paramagnetic resonance (HFEPR) measurements indicated that compound 1 possesses D = -54.8 cm -1 and E ∼ 0 cm -1 . These findings were subsequently confirmed by other experimental data, including DC magnetic susceptibilities and variable temperature and variable magnetic field reduced magnetizations. Additionally, we conducted a series of AC magnetic susceptibility measurements to investigate the kinetics of magnetization relaxation. Below 6.6 K and under zero external magnetic field, fast quantum tunneling of magnetization (QTM) dominates (∼570 Hz), and temperature-independent out-of-phase signals are observed. Above 8.1 K, temperature-dependent behavior is observed. Furthermore, we examined the AC magnetic susceptibility behavior under external magnetic fields ranging from 300 to 4000 G. The effect of QTM is significantly reduced in the presence of an external magnetic field. Temperature-dependent behavior is primarily governed by Raman relaxation. Through structural analysis of compound 1 and a series of pure nitrogen-coordinated single-ion magnets (SIMs), we propose that the oxo substituents from the double-deprotonated form of the 2,2'-bipyridine-6,6'-diol ligands donate their negative charge to the pyridine ring, forming amido anion sites. This triggers a more pronounced out-of-phase signal than that observed in pure pyridine-coordinated compounds. Moreover, we observed intermolecular interactions, including intermolecular hydrogen bonding, which, to some extent, influenced the slow relaxation of molecules. Therefore, we speculate that the slow relaxation phenomenon of compound 1 may be attributed to the combination of oxo back-donating effects and intermolecular interactions., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Facilely synthesized peroxidase-like nanozymes with high catalytic activity and stability may serve as effective biocatalysts. The present study synthesizes peroxidase-like nanozymes with multinuclear active sites using two-dimensional (2D) metal-organic framework (MOF) nanosheets and evaluates them for their practical applications. A simple method involving a one-pot bottom-up reflux reaction is developed for the mass synthesis of (Cu-S) n MOF 2D nanosheets, significantly increasing production quantity and reducing reaction time compared to traditional autoclave methods. The (Cu-S) n MOF 2D nanosheets with the unique coordination of Cu(I) stabilized in Cu-based MOFs demonstrate impressive activity in mimicking natural peroxidase. The active sites of the peroxidase-like activity of (Cu-S) n MOF 2D nanosheets were predominantly verified as Cu(I) rather than Cu(II) of other Cu-based MOFs. The cost-effective and long-term stability of (Cu-S) n MOF 2D nanosheets make them suitable for practical applications. Furthermore, the inhibition of the peroxidase-like activity of (Cu-S) n MOF nanosheets by glutathione (GSH) could provide a simple strategy for colorimetric detection of GSH against other amino acids. This work remarkably extends the utilization of (Cu-S) n MOF 2D nanosheets in biosensing, revealing the potential for 2D (Cu-S) n MOFs.

An intriguing stereoselective visible-light photocatalysis of dihydroquinoxalinone derivatives has been realized via cyclization with or without the solvolysis cascade. The reactions provided the polycyclic ring structures with efficient formation of multiple bonds and with high stereoselectivity. X-ray crystallography unequivocally determined the structures of five polycyclic products.

The organocatalytic α-alkylation of vinylogous carbonyl compounds to hydroxynitroolefins for the synthesis of hemiacetals was realized with excellent enantioselectivities and in high yields. High diastereoselectivity (up to >20:1) has been accomplished with the addition of Et 3 N. The α- and γ-alkylation of vinylogous ketone against nitroolefins displayed high but opposite facial selectivities. Transformation of the hemiacetal products to other polycyclic compounds, including the euroticin B analog, has been demonstrated.

The structural phase transition of synthetic ZnFe 2 O 4 nanoparticles (ZFO NPs) is investigated as a function of pressure up to 40.6 GPa at room temperature for the first time, and its associated intriguing electrical transport properties are resolved from in situ impedance spectra and magnetoresistivity measurements. Significant anomalies are observed in the properties of the grain boundary resistance ( R gb ), the relaxation frequency ( f max ), and the relative permittivity (ε r ) in the ZFO NPs under the pressures around 17.5-21.5 GPa. These anomalies are believed to be correlated with a cubic-to-orthorhombic phase transition of ZnFe 2 O 4 at the pressures between 21.9 and 25.7 GPa, which is found to be partially reversible. The pressure-tuned dielectric properties are measured for the cubic and the orthorhombic phases of ZFO, respectively. Remarkably, R gb decreases up to 6 orders of magnitude as a function of pressure in the cubic phase. The dielectric polarization is obviously strengthened with increased f max and decreased ε r with pressure in the orthorhombic phase. Furthermore, it is confirmed that the external pressure effectively improves the electrochemical stability of the sample based on the cycled measurements of the impedance spectra at various pressures. The changes in the complex permittivity (ε', ε″) and the dielectric loss tangent (tan δ) with frequency reveal the irreversible increase in the dielectric loss accompanied by phase transition. The MR measurements indicate that ZFO NPs are superparamagnetic under high pressure of up to 40 GPa. The transmission electron microscopy images reflect the decrease in the grain boundary number and some local amorphization of grains after compression, which provides good explanations for the changes in the electrical transport properties as a function of pressure. Herein, the structural and electrical properties of ZnFe 2 O 4 NPs generated are preserved by quenching the high-pressure phase to ambient conditions, thus providing great choices of ferrites materials for a variety of applications.