Crystal Structure Analysis Research Articles

Conflicting Aromaticity in Trirhodium(I) Rosarin.

Aromaticity is one of the most important and widely used concepts in chemistry. Among the various experimentally discovered and theoretically predicted compounds that possess different types of aromaticity, conflicting aromaticity, where aromatic and antiaromatic electron delocalization is present in one molecule simultaneously, remains one of the most controversial and elusive concepts, although theoretically predicted 15 years ago. In this work, we synthesized a novel conflicting aromatic trirhodium complex that contains a σ-aromatic metal fragment surrounded by the π-antiaromatic organic ligand and characterized it by nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, and X-ray single crystal structure analysis. Experimental characterization and quantum chemical calculations confirm the unique conflicting aromaticity of the synthesized trirhodium molecule. Thus, this novel conflicting aromatic molecule expands the family of aromatic compounds. This discovery will enable researchers to develop and understand the phenomena of conflicting aromaticity in chemistry.

A New Family of SO42–‐Templated 3d‐4f High‐Nuclearity Clusters: Syntheses, Structures, and Magnetic Properties†

Comprehensive SummaryThe precise syntheses of transition–rare‐earth metal clusters with desired structures remain a great challenge. Herein, by utilizing SO42– anion released by in‐situ decomposition of sodium dodecyl sulfate (SDS) as a template, a series of novel high‐nuclearity 3d‐4f clusters, formulated as [Ni24Pr22(μ3‐OH)31(pida)24(SO4)4(NO3)9(CH3COO)3]·Br4·(NO3)11·16H2O·25CH3OH (1, H2pida = N‐phenyliminodiacetic acid), [Ni24Nd22(μ3‐OH)31(pida)24(SO4)4(NO3)9(CH3COO)3]·Br4·(NO3)11·14H2O·24CH3OH (2) and [Ni24Gd22(μ3‐OH)36(bida)24(SO4)7(NO3)3(CH3COO)3]·(SO4)·Br4·(NO3)4·31H2O·32CH3OH (3, H2bida = N‐benzyliminodiacetic acid), have been successfully isolated. X‐ray crystal structure analyses reveal that all the cationic {Ni24RE22} cores in 1—3 possess a ball‐like structure with C3v symmetry, and can be viewed as consisting of an inner {RE22} core and an outer {Ni24} shell. From 1 and 2 to 3, due to the lanthanide contraction effect, the coordination numbers for rare‐earth metal centers in {RE22} are different, resulting in different number of SO42– and NO3– anions to support and stabilize the skeleton structures. Meanwhile, the magnetic properties of complexes 1—3 were also studied. The result revealed that complexes 1—3 show antiferromagnetic/ferrimagnetic interactions, and 3 exhibits magneto‐caloric effect at ultralow temperatures with a maximum –ΔSm (magnetic entropy change) value of 33.03 J·kg−1·K−1 at 3.0 K and 7 T.

Tandem Four-Component Reaction to Access Fused Polycycles Exhibiting Aggregation-Enhanced Through-Space Charge Transfer Emission.

Rapid construction of new fluorescence emitters is essential in advancing synthetic luminescent materials. This study illustrated a piperidine-promoted reaction of chiral dialdehyde with benzoylacetonitrile and malonitrile, leading to the formation of the 6/6/7 fused cyclic product in good yield. The proposed reaction mechanism involves a dual condensation/cyclization process, achieving the formation of up to six bonds for fused polycycles. The single crystal structure analysis revealed that the fused cyclic skeleton contains face-to-face naphthyl and cyanoalkenyl motifs, which act as the electronic donor and acceptor, respectively, potentially resulting in through-space charge transfer (TSCT) emission. While the TSCT emissions were weak in solution, a notable increase in luminescence intensity was observed upon aggregation, indicating bright fluorescent light. A series of theoretical analyses further supported the possibility of spatial electronic communication based on frontier molecular orbitals, the distance of charge transfer, and reduced density gradient analysis. This work not only provides guidance for the one-step synthesis of complex polycycles, but also offers valuable insights into the design of aggregation-enhanced TSCT emission materials.

Analysis of Blackening Reaction of Zn–Mg–Al Alloy Coated Steel Prepared by Anodizing Process

The rising demand for black-treated steel faces challenges with conventional black painting due to issues like scratching and peeling, impacting corrosion resistance and aesthetics. This study explores an alternative method, anodic oxidation, to blacken the surfaces of galvanized or coated steel plates. Parameters like temperature, duration, current density, and gas type were varied during the blackening process. The investigation aimed to identify key factors influencing the blackening. Scanning electron microscopy observed the morphology, while energy-dispersive X-ray spectroscopy and glow discharge mass spectrometry analyzed the chemical composition distribution. X-ray diffraction and X-ray photoelectron spectroscopy conducted compound crystal structure analysis. Results indicate higher temperatures, longer durations, and higher current densities improve blackening through anodic oxidation. Increased magnesium proportion on the surface leads to roughness and porous magnesium oxide formation, enhancing light absorption and explaining the observed blackening effect.

A biologically inspired fluorescent probe with enhanced sensing performance for detection of Al3+ based on metal replacement strategy

Salicylaldehyde acyl-hydrazone derivatives have been widely applied to design fluorescent probe for Al3+ detection, but they are always restricted to detect Al3+ in water and actual samples by their poor solubility, low sensitivity, and long response time. Biologically inspired, four salicylaldehyde acyl-hydrazone compounds were designed and synthesized and H4L1 as one of them was selected for in-situ assembly of the ytterbium complex (FP-Al), which has been developed to be a new fluorescent probe for Al3+ detection by the central mental displacement process. The in-situ structure transformation from FP-Al to Al-L was fully characterized by X-ray crystal structure analysis, 1H NMR, FT-IR, and spectral analysis. The intrinsic driving force was explained and elaborated by theoretical calculation. FP-Al showed a significant visible fluorescence enhancement and near-infrared luminescence decreased upon the addition of Al3+. Compared with the ligand H4L1, FP-Al showed enhanced sensing performance during Al3+ detection, especially in improving water solubility and selectivity to Al3+, promoting response speed, reducing background fluorescence and increase cell-membrane permeability. The application of spontaneous metal replacement reaction might be able to provide a new strategy to develop high-performance optical chemo-sensors.

Synthesis, crystal structure and Hirshfeld surface analysis of Mn(II) coordination compounds with ONO-donor ligands derived from ampyrone

Four manganese(II) coordination compounds, [Mn2(L1)2(NCS)2(MeOH)2] (1) [Mn(HL2)2(NCS)2(MeOH)2] (2) [Mn2(L3)2(NCS)2(MeOH)2] (3) and [Mn(HL3)2(NCS)2(MeOH)2] (4) have been synthesized from the reaction of MnCl2·4H2O, KSCN and Schiff base ligands derived from 4-aminoantipyrine (HL1= (E)-4-((2-hydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one; HL2 = (E)-4-((2-hydroxy-3-methoxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one and HL3 = (E)-4-((5-bromo-2-hydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one) in methanol and the products have been characterized with single crystal X-ray diffraction (SC-XRD). The detailed studies involve the synthesis, crystal structure, FT-IR spectroscopy, UV–Vis spectroscopy, bond sum valence calculations, elemental and Hirshfeld surface analyses. In the case of 1 and 3, the phenolate bridged dinuclear MnII complexes are formed by chelating two Schiff base ligands, two thiocyanates and two methanol molecules and two crystallographically equivalent MnII ions are connected together by phenolate oxygen with the Mn···Mn distance of 3.1618(4) (in 1) and 3.1910(6) Å (in 3). In the case of 2 and 4, the octahedral coordination geometry of the MnII center in these mononuclear species is formed by chelating two Schiff base ligands, two thiocyanates and two methanol molecules. The presence of intermolecular hydrogen bond in 2 leads to the formation of molecular chains within the layers. Also, the presence of efficient π···π interactions between pyrazolone and phenyl rings and intermolecular hydrogen bonding in 4 lead to the formation of molecular chains within the layers. All of the intermolecular and intramolecular interactions have been studied by Hirshfeld surface analyses.

Synthesis, characterisation, X-ray diffraction and biological evaluation of new thiourea derivatives against Mycobacterium tuberculosis and cervical cancer

In this study, thiourea derivatives were prepared to identify potentially effective compounds against tuberculosis and cervical cancer. The newly synthesized compounds, namely N-(cyclohexyl(methyl)carbomothioyl) benzamide (TU1), N-(cyclohexyl(methyl)carbamothioyl)-2-methylbenzamide (TU2), N-(dicyclohexylcarbamothioyl) benzamide (TU3), N-(dicyclohexylcarbamothioyl)-4-nitrobenzamide (TU4), N-(diphenylcarbamothioyl) benzamide (TU5), and N-(diphenylcarbamothioyl)-4-nitrobenzamide (TU6), were obtained in high purity and yields. The compounds were successfully characterized by infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), nuclear magnetic resonance (NMR), single crystal X-ray diffractometer (SCXRD), mass spectrometry (MS) and the melting points (mp). Crystal structure analyses of TU1, TU2 and TU6 were carried out which showed, that in the solid state, the molecules were linked together by intermolecular hydrogen bonds, specifically NH⋯S and CH⋯O interactions. In-vitro testing against M. tuberculosis (Mtb) revealed compounds TU1 and TU2 to be the most potent with MIC90 values of 28.2 and 11.2 μM, respectively. However, compounds TU4, TU5, and TU6, with MIC90 values of 80.3, 82.8 and 107.7 µM, respectively, exhibit mild antituberculosis activity, whereas TU3 with a MIC90 value of 752.7 µM is considered inactive against the Mtb strain. None of the compounds demonstrated significant selectivity for bacterial cells versus human cells and thus further studies could be dedicated to creating derivatives of TU1 and TU2 that are more selective. In vitro biological screening against HeLa cells revealed two highly toxic compounds, TU2 and TU6, with respective IC50 values of 12.00 ± 1.21 μM (SI = 1.06) and 8.45 ± 1.21 μM (SI = 0.08); and two moderately toxic compounds, TU4 (IC50 = 27.75 ± 1.15 µM; SI = 0.35) and TU5 (IC50 = 23.66 ± 1.24 µM; SI = 0.29).

Functional and structural dissection of glycosyltransferases underlying the glycodiversity of wolfberry-derived bioactive ingredients lycibarbarspermidines

Lycibarbarspermidines are unusual phenolamide glycosides characterized by a dicaffeoylspermidine core with multiple glycosyl substitutions, and serve as a major class of bioactive ingredients in the wolfberry. So far, little is known about the enzymatic basis of the glycosylation of phenolamides including dicaffeoylspermidine. Here, we identify five lycibarbarspermidine glycosyltransferases, LbUGT1-5, which are the first phenolamide-type glycosyltransferases and catalyze regioselective glycosylation of dicaffeoylspermidines to form structurally diverse lycibarbarspermidines in wolfberry. Notably, LbUGT3 acts as a distinctive enzyme that catalyzes a tandem sugar transfer to the ortho-dihydroxy group on the caffeoyl moiety to form the unusual ortho-diglucosylated product, while LbUGT1 accurately discriminates caffeoyl and dihydrocaffeoyl groups to catalyze a site-selective sugar transfer. Crystal structure analysis of the complexes of LbUGT1 and LbUGT3 with UDP, combined with molecular dynamics simulations, revealed the structural basis of the difference in glycosylation selectivity between LbUGT1 and LbUGT3. Site-directed mutagenesis illuminates a conserved tyrosine residue (Y389 in LbUGT1 and Y390 in LbUGT3) in PSPG box that plays a crucial role in regulating the regioselectivity of LbUGT1 and LbUGT3. Our study thus sheds light on the enzymatic underpinnings of the chemical diversity of lycibarbarspermidines in wolfberry, and expands the repertoire of glycosyltransferases in nature.

Gradual or Hysteretic Transition: Anion Effects on Cobalt(II) Spin Crossover Complexes

Comprehensive SummaryTo better understand the impact of different anions on the structures and SCO properties of the CoII SCO complexes, six new complexes [Co(terpy‐CH2OH)2]A2·sol (terpy‐CH2OH = 4′‐(hydroxymethyl)‐2,2′;6′,2″‐terpyridine, A = Br– (1, sol = 1.5H2O), I– (2), N3– (3, sol = 2H2O), H3BCN– (4), OTf– (5), and TsO– (6, sol = 4H2O·CH3CN), have been synthesized and characterized. All six compounds consist of mononuclear [Co(terpy‐CH2OH)2]2+ cations and charge‐balancing anions that differ in size, shape, and hydrogen bonding capacity. Complexes 1, 2, 3, and 6 displayed incomplete gradual SCO transitions, whereas 4 and 5 exhibited abrupt hysteretic spin transitions with loops of 12 and 16 K (250.0—262.0 K for 4, and 370.0—386.0 K for 5, respectively), closely resembling our previously reported complexes with SCN– and SeCN– anions. The occurrence of the order‐disorder transition of the CH2OH groups and their transition temperatures are determined by the size and hydrogen bonding capability of the anions. Remarkably, the transition temperatures of complexes with H3BCN–, SCN–, OTf–, and SeCN– anions exhibit an upward trend as the size and mass of the anions increase, as confirmed through detailed single crystal structure analyses conducted in both high‐spin and low‐spin states for all four complexes.

Electrocatalytic facets of a newly designed cobalt(III) complex towards sustainable hydrogen evolution

A hybrid cobalt complex (C7H10ON)[Co(L)2].CH3OH (Co-complex) bearing an organic cation and anionic cobalt complex has been designed, synthesized, and structurally characterized. The tridentate chelator, 2-((2-hydroxybenzylidene)amino)-4-methylphenol (H2L), was prepared by the condensation reaction between salicylaldehyde and 4-methyl-2-amino phenol. Crystal structure analysis reveals a slight distortion in the octahedral coordination geometry of the cobalt(III) centre. This complex was evaluated in the hydrogen evolution reaction (HER) using a glassy carbon working electrode in acetonitrile (ACN), using tBu4NClO4 as the supporting electrolyte. The catalyst exhibited heightened catalytic activity when acetic acid was introduced, leading to a significant elevation in the catalytic wave at −1.6 V (V vs. Ag wire). The most pronounced activity was observed by adding 15 mM acetic acid, with a turnover number (TON) of 10.1. The catalyst’s durability was confirmed through controlled potential electrolysis (CPE) at −1.6 V for 2 h, displaying a steady current for the initial 20 min, followed by a gradual increase over the subsequent 2 h. A negligible amount of deposited metallic cobalt on the surface of the glassy carbon electrode through a ligand dissociation was evident during the electrocatalytic studies, as ensured by X-ray Photoelectron Spectroscopy (XPS) analysis. Further, the presence of ligand-centric reduction wave in the complex signifies the synergistic effect of the M−L cooperation and offers a plausible ECEC mechanistic route for the release of molecular hydrogen.

Rational Design of the Spatial Effect in a Fe(II)/α‐Ketoglutarate‐Dependent Dioxygenase Reverses the Regioselectivity of C(sp3)‐H Bond Hydroxylation in Aliphatic Amino Acids

The hydroxylation of remote C(sp3)‐H bonds in aliphatic amino acids yields crucial precursors for the synthesis of high‐value compounds. However, accurate regulation of the regioselectivity of remote C(sp3)‐H bonds hydroxylation in aliphatic amino acids continues to be a common challenge in chemosynthesis and biosynthesis. In this study, the Fe(II)/α‐ketoglutarate‐dependent dioxygenase from Bacillus subtilis (BlAH) was mined and found to catalyze hydroxylation at the γ and δ sites of aliphatic amino acids. Through crystal structure analysis, molecular dynamic simulation and quantum chemical calculations revealed that regioselectivity was regulated by the spatial effect of BlAH. Based on this result, the spatial effect of BlAH was reconstructed to stabilize the transition state at the δ site of aliphatic amino acids, thereby successfully reversing the γ site regioselectivity to the δ site. For example, the regioselectivity of L‐Homoleucine (5a) was reversed from the γ site (1:12) to the δ site (>99:1). The present study not only expands the toolbox of biocatalysts for the regioselective functionalization of remote C(sp3)‐H bonds, but also provides a theoretical guidance for the precision‐driven modification of similarly remote C(sp3)‐H bonds in complex molecules.

Rational Design of the Spatial Effect in a Fe(II)/α-Ketoglutarate-Dependent Dioxygenase Reverses the Regioselectivity of C(sp3)-H Bond Hydroxylation in Aliphatic Amino Acids.

The hydroxylation of remote C(sp3)-H bonds in aliphatic amino acids yields crucial precursors for the synthesis of high-value compounds. However, accurate regulation of the regioselectivity of remote C(sp3)-H bonds hydroxylation in aliphatic amino acids continues to be a common challenge in chemosynthesis and biosynthesis. In this study, the Fe(II)/α-ketoglutarate-dependent dioxygenase from Bacillus subtilis (BlAH) was mined and found to catalyze hydroxylation at the γ and δ sites of aliphatic amino acids. Through crystal structure analysis, molecular dynamic simulation and quantum chemical calculations revealed that regioselectivity was regulated by the spatial effect of BlAH. Based on this result, the spatial effect of BlAH was reconstructed to stabilize the transition state at the δ site of aliphatic amino acids, thereby successfully reversing the γ site regioselectivity to the δ site. For example, the regioselectivity of L-Homoleucine (5a) was reversed from the γ site (1:12) to the δ site (>99:1). The present study not only expands the toolbox of biocatalysts for the regioselective functionalization of remote C(sp3)-H bonds, but also provides a theoretical guidance for the precision-driven modification of similarly remote C(sp3)-H bonds in complex molecules.

Crystal structure and Hirshfeld surface analysis of dimethyl 2-oxo-4-(pyridin-2-yl)-6-(thiophen-2-yl)cyclohex-3-ene-1,3-dicarboxylate

In the title compound, C19H17NO5S, the cyclohexene ring adopts nearly an envelope conformation. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming a three-dimensional network. In addition, C—H...π interactions connect the molecules by forming layers parallel to the (010) plane. According to the Hirshfeld surface analysis, H...H (36.9%), O...H/H...O (31.0%), C...H/H...C (18.9%) and S...H/H...S (7.9%) interactions are the most significant contributors to the crystal packing.

Challenging of ECMO application in pediatric restrictive cardiomyopathy: case report of a novel TNNI3 variant

BackgroundRestrictive cardiomyopathy (RCM) represents a rare cardiovascular disorder stemming from filament-associated genes. Nonetheless, treating RCM presents considerable challenges, particularly concerning device implantation and mechanical support. Furthermore, elucidating the molecular function of specific variants holds promise in benefiting patients and enhancing prognosis, given the significant heterogeneity among RCM variants.Case presentationThe proband, an eight-year-old female, was admitted to our hospital post cardiopulmonary resuscitation due to sudden cardiac arrest. Echocardiography revealed bilateral atrial enlargement. Whole-exome sequencing uncovered a novel heterozygous mutation (c.509G>A, p.R170Q) in TNNI3. Evaluation using the MutationTaster application deemed c.509G>A pathogenic (probability = 0.99). Following clinical manifestations, imaging assessments, and genetic screening, the proband received an RCM diagnosis. ECMO was recommended along with continuous renal replacement therapy. However, persistent atrial flutter ensued post-ECMO withdrawal. Attempts to restore cardiac rhythm with cardioversion, metoprolol, and amiodarone proved futile. Subsequent heart failure led to the patient's demise due to cardiac shock. Based on crystal protein structural analysis, we observed that cTnI-R170Q and R170W exerted similar impacts on protein structural stability and formation. However, both differed significantly from cTnI-R170G, primarily influencing amino acid regions 32–79 and 129–149, involved in TnC and actin binding. Therefore, cTnI-R170Q was revealed to induce RCM via the same molecular mechanism as cTnI-R170W.ConclusionManaging RCM remains a critical challenge. This study underscores the discouragement of device implantations for cardiac pump functional support in RCM, particularly for non-short-term scheduled HTx. Additionally, considering catheter ablation for atrial fibrosis-induced AFs is recommended. Mechanistically, cTnI-R170Q primarily diminishes troponin-actin interactions and destabilizes thin filaments.

Theoretical Determination of the Electronic Structures and Energy-Level Splitting for Pr3+-Doped Y2SiO5 Crystals.

Trivalent praseodymium (Pr3+)-doped yttrium silicate (Y2SiO5) crystals have been widely used in various phosphors owing to their excellent luminescence characteristics. Although a series of studies have been carried out on its application prospects, the electronic structures and energy-transfer mechanisms of Pr3+-doped Y2SiO5 (Y2SiO5:Pr) remain an exploratory topic. Herein, the crystal structure analysis by the particle swarm optimization structure search method is used to study the structural evolution of Y2SiO5:Pr. Two novel structures with local [PrO7]-11 and [PrO6]-9 [Y2SiO5:Pr (I) and Y2SiO5:Pr (II)] are successfully identified. The impurity Pr3+ ions occupy the Y3+ sites and successfully integrate into the Y2SiO5 host crystal with a Pr3+ concentration of 6.25%. The calculated electronic band structures show that the doping of Pr3+ induces a reduction in band gaps for the host Y2SiO5 crystal. The conduction bands near the Fermi level are completely composed of f states. For the atomic energies of Pr3+ in Y2SiO5, the Stark levels and transitions are properly simulated based on a new set of crystal field parameters (CFPs) at the C1 site symmetry. A satisfactory r.m.s. dev. of 15.57 cm-1 with 9 free ion parameters (plus 27 fixed CFPs as obtained from ab initio calculation) fitted to the 33 observed levels is obtained for the first time. The plentiful energy-level transition lines, from the visible light to the near-infrared region, are deciphered for Pr3+ in Y2SiO5. Blue 3P0 → 3H4 at 465 nm is calculated to be a strong emission line, and it might be an ideal channel for laser actions. These results could not only provide important insights into the rare-earth-doped crystals but also lay the foundation for future research studies of designing the new laser materials.

Anti-cancer activities based on ZnII complex of potassium 5-thiophen-2-yl-[1,3,4]-oxadiazole-2-thiolate: Synthesis, crystal structure, photoluminescence study and Hirshfeld analysis

Recent advancements in developing the most suitable drug for humankind to cure cancer have paved the way to synthesize an alternative to platinum-based drugs. Herein, the synthesis of novel polymeric complex [Zn(thot)2]n (1) derived from potassium 5-thiophen-2-yl-[1,3,4]-oxadiazole-2-thiolate (Kthot) is reported. The synthesized ligand and complex were characterized by infrared, NMR, Mass and UV–vis. spectrometry. Moreover, single-crystal X-ray analysis revealed the polymeric nature of the [Zn(thot)2]n (1). Complex 1 is stabilized via various types of intermolecular interactions. The intermolecular interaction found in complex 1 was further investigated through Hirshfeld surface analysis. Emission spectra data showed that complex [Zn(thot)2]n (1) exhibits higher fluorescent intensity than Kthot. The cytotoxicity of complex 1 and Kthot was evaluated against MDA-MB-231 breast cancer cells, which was determined by measuring mitochondrial dehydrogenase activity using MTT as substrate. The result showed that they both suppressed the viability of cancer cells. Moreover, complex 1 was found to be more effective than ligand salt Kthot. The IC50 value for complex 1 was found around 37.43 μM whereas for Kthot it is 69.24 μM which suggests that complex 1 reduces the cell viability more effectively in comparison to the ligand salt.

High frequency enhancement of dielectric constant, crystal structure analysis, and magnetic properties of Pr3+- Zn2+ substituted Co2Y-type barium hexagonal ferrites

The effect of Pr3+-Zn2+ doping on the magnetic and dielectric properties of Co2Y-type barium hexaferrites with the chemical composition Ba2Co2Fe12-x-yPrxZnyO22 (x = 0.00, 0.10, 0.20, and y = 0.00, 0.15, 0.25), was investigated in this study. The prepared Pr3+-Zn2+ substituted Co2Y-type barium hexaferrites were calcined for 5 h at 1100 °C in a digital heating chamber. The XRD analysis confirms the presence of a crystalline phase in the undoped Co2Y-type barium hexaferrite samples, with a space group identified as R-3m. Characteristic absorption bands of Co2Y-type barium hexaferrites were observed at 540 and 422 cm−1 due to the asymmetric stretching vibration of Fe3+ and O2− at both, octahedral and as well as tetrahedral crystallographic sites. The magnetic interaction between the particles causes slight agglomeration. Dielectric and impedance spectroscopy were performed using Koop's phenomenological theory and the Maxwell-Wagner two-layer dielectric relaxation model. The ε′ was found to decrease with an increase in applied frequency due to the space-charge polarization phenomenon. The rise in ε′ at higher frequencies enhances the material's suitability for high-frequency applications. The magnetic parameters were extracted from the M − H hysteresis loop, and it was observed that they were affected by the site preferences of Pr3+ and Zn2+. The prepared Y-type hexaferrite's optimized magnetic parameters make it a good option for magnetic memory applications.

Construction of coordination polymer [Ni(ppda) (tib) (H2O)]·H2O and photocatalytic degradation of indigo carmine

Semiconductor coordination polymers have garnered significant attention as photocatalysts for wastewater treatment owing to their adaptable structure, expansive specific surface area, and outstanding selectivity, stability, and sensitivity. In this study, coordination polymer [Ni(ppda) (tib) (H2O)]·H2O was synthesized utilizing flexible phenyldiacetic acid (H2ppda) and rigid 1,3,5-tris(1-imidazolyl)benzene (tib). Crystal structure analysis revealed that the three-linked tib ligands and the central Ni(II) ion create a wavy 2D surface. Additionally, cis-ppda2- ligands form a 1D wave chain alongside central Ni(II), which traverse through a 2D layer. Adjacent layers are interlaced via ppda2−, resulting in a complex 3D supramolecular structure. The fundamental framework of [Ni(ppda) (tib) (H2O)]·H2O exhibits stability up to 316 °C and remains stable over 5 cycles, with a band gap energy of 2.9 eV, rendering it a viable candidate for catalytic applications. In aqueous systems, [Ni(ppda) (tib) (H2O)]·H2O demonstrates efficient photocatalytic degradation of Indigo Carmine (IC), achieving a degradation rate of 98.5% and a reaction rate of 0.027 min−1, showcasing commendable selectivity and semiconductor properties. The primary photocatalytic degradation mechanism involves the synergistic formation of ·OH and ·O2- active species through the interaction between [Ni(ppda) (tib) (H2O)]·H2O and H2O2, facilitating the oxidative degradation of dye molecules.

Regulating effect of the halogen atoms on the cofacial dinuclear Schiff base complexes: Synthesis, spectroscopy, electrochemistry, and DFT calculations

The present study reports the synthesis and characterization of two new halogenated Schiff base copper (II) derivatives, namely [CuII2(3‐Cl‐Salmphen)2] (Cu‐Cl‐Salmphen) and [CuII2(3‐Br‐Salmphen)2] (Cu‐Br‐Salmphen), which were characterized by UV–Vis, FT‐IR, 1H‐NMR, and 13C‐NMR spectroscopy. Single crystal structural analysis revealed that each complex contains two crystallography independent, distorted copper centers, where each Cu center exhibits the same coordination environment with N2O2 donor atoms from two different ligands. To investigate the substitution effect of halogen atoms on the properties of the complexes, the non‐halogenated isomer [CuII2(H‐Salmphen)2] (Cu‐H‐Salmphen) was introduced for comparison. The differences between the halogenated and the non‐halogenated analogues were compared through spectroscopic, electrochemical, DFT, and TD‐DFT theoretical calculations. The optical experimental results indicated that the introduction of halogen atoms decreased the energy gap between the ground and excited states, leading to enhanced optical absorption capabilities of the compounds. Electrochemical tests showed that the halogenated analogues exhibited better electrochemical performance, and with the increase in an atomic number of the halogen atoms, the compounds displayed a gradual increase in cyclic voltammetry peak areas, diffusion coefficients, and conductivities. Theoretical calculations revealed that the introduction of halogen atoms simultaneously expanded the conjugated area of the molecules, decreased the HOMO‐LUMO energy levels of the complexes, and strengthened the intramolecular interactions. Furthermore, the potential mechanism of the tuning effect of halogen atoms on the charge transfer process was proposed.

Preparation of a class of cucurbit[6]uril-light rare-earth-based supramolecular assemblies and its efficient detection of chloramphenicol

By introducing 4,4′-naphthalenedisulfonic acid (4,4′-H2BPs) as a structure-induced agent, four novel cucurbit[6]uril-based supramolecular assemblies have been successfully prepared in the cucurbit[6]uril (Q[6]) system with light rare-earth elements (La3+, Ce3+, Pr3+, Nd3+) under hydrothermal conditions. Crystal structure analysis shows that the assemblies 1 (La3+), 2 (Ce3+), 3 (Pr3+) are isomorphism 3D frameworks, where Q[6] can directly coordinate with light rare-earth metal ions to form 1D −Ln(III)- Q[6]-Ln(III)- chains, while the 4 (Nd3+) presents 3D structures stacking by the unit of Q[6]@Nd3+@Q[6]@Nd3+@Q[6], respectively. In these structures, 4,4′-H2BPs ligands all can act as an organic counter anion and bridging via the outer-surface interaction of cucurbit[n]uril (OSIQ) in the system, which is the main driving force from low-dimensional to high-dimensional. Meanwhile, the fluorescence sensing performance of the two assemblies for antibiotics was investigated, and the results showed that assembly 1 could be used as a promising fluorescent sensor material to detect chloramphenicol (CAP).