Crystal Analysis Research Articles

Development of Inhibitory Compounds for Metallo-beta-lactamase through Computational Design and Crystallographic Analysis.

Metallo-β-lactamases (MBL) deactivate β-lactam antibiotics through a catalytic reaction caused by two zinc ions at the active center. Since MBLs deteriorate a wide range of antibiotics, they are dangerous factors for bacterial multidrug resistance. In this work, organic synthesis, computational design, and crystal structure analysis were performed to obtain potent MBL inhibitors based on a previously identified hit compound. The hit compound comprised 3,4-dihydro-2(1H)-quinolinone linked with a phenyl-ether-methyl group via a thiazole ring. In the first step, the thiazole ring was replaced with a tertiary amine to avoid the planar structure. In the second step, we virtually modified the compound by keeping the quinolinone backbone. Every modified compound was bound to a kind of MBL, imipenemase-1 (IMP-1), and the binding pose was optimized by a molecular mechanics calculation. The binding scores were evaluated for the respective optimized binding poses. Given the predicted binding poses and calculated binding scores, candidate compounds were determined for organic syntheses. The inhibitory activities of the synthesized compounds were measured by an in vitro assay for two kinds of MBLs, IMP-1 and New Delhi metallo-β-lactamase (NDM-1). A quinolinone connected with an amine bound with methyl-phenyl-ether-propyl and cyclohexyl-ethyl showed a 50% inhibitory concentration of 4.8 μM. An X-ray crystal analysis clarified the binding structure of a synthesized compound to IMP-1. The δ-lactam ring of quinolinone was hydrolyzed, and the generated carboxyl group was coordinated with zinc ions. The findings on the chemical structure and binding pose are expected to be a base for developing MBL inhibitors.

Palladium-Catalyzed Arylation of C(sp2)-H Bonds and C(sp3)-H Bonds with 4-Amino-benzotriazole as the Bidentate Directing Group.

The arylation of C(sp2)-H and C(sp3)-H bonds in carboxylic acids catalyzed by Pd(II) with 4-aminobentriazole as the directing group was investigated. In addition to activation of the C(sp2)-H bond, selective arylation of alkyl carboxylic acids and amino acids in the β position can also be achieved. This strategy involved a 5,5-bicyclic Pd intermediate complex whose structure was determined by X-ray single crystal diffraction analysis. Importantly, the DG (directing group) can be easily removed under mild conditions.

Novel Insecticidal Butenolide-Containing Methylxanthine Derivatives: Synthesis, Crystal Structure, Biological Activity Evaluation, DFT Calculation and Molecular Docking.

The design of novel agrochemicals starting from bioactive natural products is one of the most effective ways in the discovery and development of new pesticidal agents. In this paper, a series of novel butenolide-containing methylxanthine derivatives (Ia-Ir) were designed based on natural methylxanthine caffeine and stemofoline, and the derivatized insecticide flupyradifurone of the latter. The structures of the synthesized compounds were confirmed via1H NMR, 13C NMR, HRMS and X-ray single crystal diffraction analyses. The biological activities of the compounds were evaluated against a variety of agricultural pests including oriental armyworm, bean aphid, diamondback moth, fall armyworm, cotton bollworm, and corn borer; the results indicated that some of them have favorable insecticidal potentials, particularly toward diamondback moth. Among others, Ic and Iq against diamondback moth possessed LC50 values of 6.187 mg·L-1 and 3.269 mg·L-1, respectively, -- 2.5- and 4.8-fold of relative insecticidal activity respectively to that of flupyradifurone (LC50 = 15.743 mg·L-1). Additionally, both the DFT theoretical calculation and molecular docking with acetylcholine binding protein were conducted for the highly bioactive compound (Ic). Ic and Iq derived from the integration of caffeine (natural methylxanthine) and butenolide motifs can serve as novel leading insecticidal compounds for further optimization.

SYNTHESIS AND CHARACTERIZATION OF CaO PREPARED FROM LIMESTONE USING SOL-GEL METHOD

The sol-gel method has been successfully applied to the synthesis and characterization of calcium oxide (CaO) derived from calcite-based natural limestone from Pamekasan, Madura, East Java Indonesia. Controlled dissolution, titration, gel formation, and subsequent calcination at temperatures 650°C and 900°C were the steps involved in the synthesis. X-ray diffraction was used for characterization to identify the phase that had formed. Supporting software, MATCH! used to analyze the phases and structures and Rietica for refinement using the Rietveld method. The Ca(OH)2 phase formed was 59.65 ± 2.45 %wt before the calcination process, according to the XRD results. 23.71 ± 0.61 %wt CaO was produced by the calcination process at 650°C, and 64.52 ± 1.85 %wt was produced at 900°C. Meanwhile, after calcination at 900°C, crystal size analysis using MAUD software produced CaO with a size of 534 ± 74 nm. K CaO powder synthesized using the sol-gel method is calcined at 900°C to get a higher percentage than at 600°C. The CaO powder can be used for CO2 capture applications because it comes from natural resources and is environmentally friendly.

Pyrrole-substituted difluoroboron β-diketonate dyes: Facile synthesis and multi-state optical properties

Difluoroboron β-diketonate complexes (BF2bdks) are classic fluorescent molecules that have been applied in luminescent materials, oxygen and mechanical sensors, and most investigations concentrate on BF2bdks with varying aromatic groups without heteroatoms. In this work, a new molecular platform BF2bdks with heterocycle-substituted is prepared in one pot, and six unsymmetric π-expanded BF2bdks are synthesized via condensation reaction. B-1∼6 exhibit comparable fluorescence properties in solution, aggregated and solid states. B-3 (683 nm, Φf = 13.1 %) and B-5 (700 nm, Φf = 2.1 %) show near infra-red (NIR) emission with moderate fluorescence intensity in solution state. Solid emission of B, B-1-3 and B-5 are detected with fluorescence quantum yield from 12.8 % to 25.6 %, and B-2, B-3 and B-5 show AIE phenomenon in aggregated state. The results are supported by crystal analysis and DFT calculation in some extent. In a word, this work enriches the heterocycle-substituted BF2bdks system. B-3 and B-5 with moderate intensity NIR emission in solution, aggregated and solid states at the same time, providing a simple preparation method for multi-states luminescent dyes.

Single component long-lived dynamic room temperature phosphorescence with large-scale preparation and visible light excitation

A pure organic room temperature phosphorescence (PORTP) luminogen named as DCP was successfully prepared and showed long room temperature phosphorescence (RTP) and afterglow lifetimes (3 ms and 4 s in sequence). Meanwhile, DCP showed high fluorescence (0.14) and RTP (0.39) quantum yields in crystalline state, simultaneously presented visible light excitation and dynamic RTP. By host-guest doping and optimization, Urea/DCP doping system emitted blue RTP, with RTP and afterglow lifetimes of 341 ms of 5 s in turn. Crystal analysis and theoretical calculations indicated H stacking, large spin orbit coupling constant, and small energy gap between the lowest singlet and triplet states result in long RTP lifetime and high quantum yield for DCP. Based on long phosphorescence emission, an advanced anti-counterfeiting pattern was constructed. As far as we know, it is the first report that such small molecules containing 3, 5-dicyanopyridine show long-lived RTP in both crystalline state and doping system. In this paper, not only ultralong and blue PORTP materials with the advantage of large-scale preparation, but also single component dynamic RTP, and RTP of visible light excitation were achieved.

Air-Stable Cobalt(III) and Chromium(III) Complexes as Single-Component Catalysts for the Activation of Carbon Dioxide and Epoxides.

Cobalt(III) and chromium(III) salophen chloride complexes were synthesized and tested for the cycloaddition of carbon dioxide (CO2) with epoxides to obtain cyclic carbonates. The cat1, cat2, cat4, and cat5 complexes presented high catalytic activity without cocatalysts and are solvent-free at 100 °C, 8 bar, and 9 h. At these conditions, the terminal epoxides (1a-1k) were successfully converted into the corresponding cyclic carbonates with a maximum conversion of ∼99%. Moreover, cat5 was highlighted due to its capability of opening internal epoxides such as limonene oxide (1l) with a 36% conversion to limonene carbonate (2l), and from cyclohexene oxide (1m), cyclic trans-cyclohexene carbonate (2m) and poly(cyclohexene carbonate) were obtained with 15% and 85% selectivity, respectively. A study of the coupling reaction mechanism was proposed with the aid of electrospray ionization mass spectrometry (ESI-MS) analysis, confirming the single-component behavior of the complexes through their ionization due to epoxide coordination. In addition, crystallographic analysis of cat1 single crystals grown in a saturated solution of pyridine helped to demonstrate that the substitution of chloride ion by pyridine ligands to form an octahedral coordination occurs (Py-cat1), supporting the proposed mechanism. Also, a recyclability study was performed for cat5, and a total turnover number of 952 was obtained with only minor losses in catalytic activity after five cycles.

Crystal Plasticity Finite Element Analyses on the Formability of AA6061 Aluminum Alloy with Different Ageing Treatments

Different ageing treatments have been developed to achieve targeted properties in aluminum alloys through altering microstructures. However, there is a lack of understanding regarding the effect of ageing treatments on the formability of these alloys. In this study, we employed crystal plasticity finite element (CPFE) modeling, in conjunction with the Marciniak-Kuczynski (M-K) approach, to investigate the effects of ageing treatments on the mechanical properties and formability of AA6061 aluminum alloy. The as-received sheet was in the T6 heat treatment state, which was subjected to artificial ageing and pre-ageing, respectively, to achieve two age-hardened alloys with modified precipitation states. The microstructures and crystallographic textures of the three alloys were measured using the electron backscattering diffraction (EBSD) technique, and uniaxial tensile tests were performed along the rolling direction (RD), transverse direction (TD), and diagonal direction (DD, 45° to the RD) for each alloy. The forming limit curve (FLC) of the as-received alloy was determined using the Nakazima test. The dependence of mechanical strength, tensile ductility, and work-hardening behavior on the ageing treatments was clarified. Then, the tensile test results were utilized to calibrate the modeling parameters used in the CPFE model, whereas the FLC predictability of the developed model was validated with the experimental one. In the formability analysis, the effects of the ageing treatment on the FLC exhibit a notable dependency on loading paths, and the pre-aged alloy exhibits better formability than the other two at the plane strain tension state, thanks to its high work-hardening levels. In addition, the deformed textures along the different loading paths and the effects of the initial texture on the FLC are also discussed.

Tau-borides (Mnx{Ru,Os,Ir}1-x)23B6: X-ray single crystal and TEM data, physical properties

Investigation (electron microprobe and X-ray powder and single crystal diffraction analyses) of the phase relations in the Mn-rich corner (> 45 at% Mn) of the systems Mn-{Ru,Os,Ir}-B, prompted in all three systems a ternary compound with formula (Mnx{Ru,Os,Ir}1-x)23B6. For the systems Mn-Ru-B, Mn-Ir-B phase equilibria have been determined at 950°C (Ru), 900°C (Ir) revealing in both cases a small homogeneity region at constant B-content (Mn1-xRux)23B6 (0.29 < x < 0.37); (Mn1-xOsx)23B6 (0.33 < x < 0.37), as well as (Mn1-xIrx)23B6 (0.29 < x < 0.34). The crystal structure of the three compounds was determined from single crystal and X-ray powder intensity data analyses to be isotypic with the Cr23B6-type (so-called tau-phase, space group Fm3¯m, No. 225). In all cases Mn atoms fully occupy the 4a site (0,0,0) at the origin of the unit cell. For the 8c site (¼,¼,¼) we observed a random distribution of Mn1-x(PM)x with decreasing PM content (PM stands for a platinum group metal atom) going from Ru to Os and Ir, where Mn atoms fully occupy 8c. Whereas the remaining sites (48h, 32f) show various ratios of the two metal species, boron atoms fully occupy the centers (24e site) of the Archimedean metal atom antiprisms. A transmission electron microscopic study confirms the absence of superstructures related to these metal atom disorder, thus Mn and PM atoms randomly share their sites. The latter is well reflected in the behavior of the electrical resistivity of these compounds, which is dominated by disorder scattering. For (Mn0.6{Ru,Os}0.4)23B6, temperature dependent dc magnetization studies reveal distinct antiferromagnetic-like anomalies at TN ≅ 72 K and 114 K, respectively. Low field dc and ac magnetic susceptibility data of (Mn0.7Ir0.3)23B6 display a distinct ferromagnetic-like transition at TC = 280 K, consistent with a pronounced specific heat anomaly and a rather continuous temperature dependent evolution of magnetic anisotropy effects. Mechanical properties (hardness) characterize the tau phases among rather hard and brittle intermetallics (about 5–6 GPa).

Manipulating Single‐Molecule Exciplex TADF and Deep‐Blue RTP Through Non‐Covalent π–π Interaction in a Molecular Foldamer

AbstractAlthough the π–π stacking has been widely applied for constructing aggregated emitters in optoelectronics fields, the role of intramolecular non‐covalent π–π interactions has not been well studied. Here, a supramolecular foldermer M‐σ‐C, with the electron donor (D) and acceptor (A) units spatially separated with a non‐covalent bond at a close distance by methylene linker is designed and synthesized. This gives a face‐to‐face D/A stacking configuration with supramolecular π–π interactions. Temperature‐dependent nuclear magnetic resonance measurements and single crystal analyses confirm its folding configuration. In solutions, M‐σ‐C exhibits a single‐molecule exciplex thermally activated delayed fluorescence (TADF) property ascribing to the efficient intramolecular through‐space charge transfer (CT) process. While single‐molecule deep‐blue room temperature phosphorescence (RTP) with a long afterglow lifetime of 236 ms is observed in a nonpolar matrix, which represents the record lifetime among current 3CT‐character featured RTP. This work indicates that intramolecular non‐covalent interactions play an important role in manipulating high‐performance single‐molecule exciplex TADF and RTP, and provide a feasible molecular design strategy for supramolecular chemistry involving the development of optoelectronic materials.

Effect of phase transition on the piezoelectric properties of scandium-alloyed gallium nitride

In this study, the piezoelectric properties of scandium-alloyed gallium nitride (ScGaN), which is expected to be applied to microelectromechanical systems devices, are evaluated by first-principles calculations. The piezoelectric constant (d33) of GaN is found to increase by up to approximately 30 times upon the addition of 62.5 mol. % of Sc. The piezoelectric stress constant (e33) increases and the elastic constant (C33) decreases with increasing Sc content of ScGaN, driving the rise of d33. The improved piezoelectric properties of ScGaN compared with those of GaN are largely attributed to elastic softening, which is thought to be related to the transition from a wurtzite to hexagonal boron nitride (h-BN) structure driven by the change in bonding states between atoms caused by the addition of Sc to GaN. The crystal orbital Hamilton population analysis suggests that addition of Sc to GaN results in the combination of weaker Sc–N and Ga–N bonding, which makes the crystal structure unstable. This weakened bonding is thought to be the main cause of the destabilization of the wurtzite structure and transition to the h-BN structure of ScGaN. The elastic softening associated with this structural transition leads to the dramatic improvement in piezoelectric properties.

Unveiling structural features, chemical reactivity, and bioactivity of a newly synthesized purine derivative through crystallography and computational approaches

We introduce the synthesis and characterization of a novel purine derivative, 2-amino-6‑chloro-N,N-diphenyl-7H-purine-7-carboxamide. X-ray crystallography was utilized to elucidate its molecular and crystal structure. A comprehensive crystal packing analysis uncovered a network of diverse intermolecular interactions, including classical and unconventional hydrogen bonding. Remarkably, a unique halogen···π (C—Cl···π(ring)) interaction was identified and theoretically analyzed within a multi-approach quantum mechanics (QM) framework, revealing its lone-pair⋯π (n→π*) nature. Furthermore, insights into the electronic and chemical reactivity properties are provided by means of Conceptual Density Functional Theory (CDFT) at wB97X-D/aug-cc-pVTZ level. The compound's drug-likeness, pharmacokinetics, and toxicology profiles are assessed using ADMETlab 2.0. Finally, molecular docking simulations were conducted to evaluate its bioactivity as a potential cyclooxygenase-2 (COX-2) inhibitor. This study significantly advances our understanding of purine structure and reactivity, offering valuable insights for the development of targeted purine-based COX-2 inhibitors and anticancer therapeutics.

Exploring the formation and diversity of secnidazole cocrystals

This study investigates the cocrystallization of secnidazole (SNZ), a potent antimicrobial drug, with several coformers, overcoming the inherent stability challenges posed by its hemihydrate form to produce novel solid states. We successfully synthesized and characterized three novel cocrystals with carvacrol (CAR), fumaric acid (FMA), and 3,5-dinitrobenzoic acid (DNZ), employing synchrotron single crystal analysis to elucidate their structures. The application of Hirshfeld surface and 2D fingerprint plots further enriched our understanding of the unique packing arrangements within these cocrystals. Moreover, preliminary powder X-ray diffraction (PXRD) patterns hinted at the emergence of additional novel solid forms with salicylic acid (SLC), oxalic acid (OXA), succinic acid (SUC), citric acid (CTR), and thymol (THY). Supported by literature and a thorough analysis of molecular interactions, we propose the existence of pharmaceutical cocrystals among these newly identified solid forms. Our findings not only augment the repertoire of SNZ based pharmaceuticals but also accentuates the strategic utilization of supramolecular synthons, offering significant advancements in the understanding of novel solid form formation, and the critical role of hydrogen bonding in these processes.

Determination of Na+ Cation Locations in Nanozeolite ECR-1 Using a 3D ED Method

Until now, the comprehensive structural analysis of single crystals of zeolite ECR-1, an aluminosilicate with the EON topology, has been hindered owing to the submicron dimensions of the obtained crystals. Additionally, this zeolite, which is characterized by a topology comprising alternating periodic building units of MAZ and MOR layers, exhibits stacking faults that impede accurate refinement through the Rietveld method. In this report, we present, for the first time, the structure of ECR-1 elucidated by studying a nanocrystal with a significantly reduced number of stacking faults. The sample used was synthesized hydrothermally using trioxane as the organic structure-directing agent. The structure determination was conducted using precession electron diffraction (PED) at 103 K. Partial dehydration occurred owing to the high vacuum conditions in the TEM sample chamber. From the dynamical refinement (Robs = 0.097), 8.16 Na+ compensating cations were localized on six distinct crystallographic sites, along with approximately four water molecules per unit cell. Furthermore, a canonical Monte Carlo computational study was conducted to compare the experimental cationic distribution and location of water molecules with the simulation.

Regional-Scale Paleoproterozoic Heating Event on Archean Acasta Gneisses in Slave Province, Canada: Insights from K–Ar and 40Ar/39Ar Chronology

Slave Province in Canada is an Archean granite–supracrustal terrane at the northwestern corner of the Canadian Shield. It is bordered by the Thelon–Taltson orogen (2.0 to 1.9 Ga) to the southeast and the Wopmay orogen (1.9 to 1.8 Ga) to the west. Acasta gneisses, exposed in the westernmost Slave Province, and the Wopmay rocks, located close to the gneisses, were systematically collected for K–Ar and laser step-heating 40Ar/39Ar single-crystal analyses of the biotite and amphibole. The K–Ar biotite ages of the four Wopmay samples range from 1816 ± 18 Ma to 1854 ± 26 Ma. The 40Ar/39Ar biotite analyses of the three Wopmay samples yield plateau ages of 1826 ± 21 Ma, 1886 ± 13 Ma, and 1870 ± 18 Ma. These ages fall within the reported U–Pb zircon age range of the Wopmay orogen. The K–Ar biotite ages of the fifteen Acasta gneisses range from 1779 ± 25 Ma to 1877 ± 26 Ma, except for one younger sample (1711 ± 25 Ma). The 40Ar/39Ar analyses of the biotite crystals from three samples give the plateau ages of 1877 ± 8 Ma, 1935 ± 14 Ma, and 1951 ± 11 Ma. The K–Ar amphibole ages from twelve samples range from 1949 ± 19 Ma to 1685 ± 25 Ma. Two samples of them give ages older than the zircon U-Pb age of Hepburn plutons. The 40Ar/39Ar analyses of the amphibole crystals show varied age relations. The two samples give plateau ages of 1814 ± 22 Ma and 1964 ± 12 Ma. Some samples exhibit apparent old ages of ~2000 Ma in the middle temperature fractions. These old fractions result from the amphibole crystals, originally formed in the Archean, being affected by the thermal events during the Wopmay orogeny but not fully resetting. These observations suggest that the K–Ar system ages of the biotite and amphibole in the Archean Acasta gneiss were rejuvenated during the Paleoproterozoic ages. The Discussion explores the possibility that the heat source rejuvenating the K–Ar system ages may have arisen due to asthenospheric extrusion into the wedge mantle, a process likely triggered by subduction rollback.

Silver(i) Perfluoroalcoholates: Synthesis, Structure, and their Use as Transfer Reagents.

Herein we report a general access to silver(i) perfluoroalcoholates, their structure in the solid state and in solution, and their use as transfer reagents. The silver(i) perfluoroalcoholates are prepared by the reaction of AgF with the corresponding perfluorinated carbonyl compounds in acetonitrile and are stable for a prolonged time at -18 °C. X-Ray analysis of single crystals of perfluoroalcoholate species showed that two Ag(i) centers are bridged by the alcoholate ligands. In acetonitrile solution, Ag[OCF3] forms different structures as indicated by IR spectroscopy. Furthermore, the silver(i) perfluoroalcoholates can be used as easy-to-handle transfer reagents for the synthesis of Cu[OCF3], Cu[OC2F5], [PPh4][Au(CF3)3(OCF3)], and fluorinated alkyl ethers.

Synthesis, crystal structure and properties of the trigonal–bipyramidal complex tris(2-methylpyridine N-oxide-κO)bis(thiocyanato-κN)cobalt(II)

Reaction of Co(NCS)2 with 2-methylpyridine N-oxide in a 1:3 ratio in n-butanol leads to the formation of crystals of tris(2-methylpyridine N-oxide-κO)bis(thiocyanato-κN)cobalt(II), [Co(NCS)2(C6H7NO)3]. The asymmetric unit of the title compound consists of one CoII cation two thiocyanate anions and three crystallographically independent 2-methylpyridine N-oxide coligands in general positions. The CoII cations are trigonal–bipyramidally coordinated by two terminal N-bonding thiocyanate anions in the trans-positions and three 2-methylpyridine N-oxide coligands into discrete complexes. These complexes are linked by intermolecular C–H...S interactions into double chains that elongate in the c-axis direction. Powder X-ray diffraction (PXRD) measurements prove that all batches are always contaminated with an additional and unknown crystalline phase. Thermogravimetry and differential analysis of crystals selected by hand reveal that the title compound decomposes at about 229°C in an exothermic reaction. At about 113°C a small endothermic signal is observed that, according to differential scanning calorimetry (DSC) measurements, is irreversible. PXRD measurements of the residue prove that a poorly crystalline and unknown phase has formed and thermomicroscopy indicates that some phase transition occurs that is accompanied with a color change of the title compound.

Rapid conformational analysis of semi-flexible liquid crystals

ABSTRACT We present an approach for rapid conformational analysis of semi-flexible liquid crystals. We use a simple graphical user interface (GUI) tool that leverages rules-based methods for efficient generation of bend-angle distributions, offering a significant improvement over traditional single-conformer analysis. Our methods demonstrated proficiency in approximating molecular shapes comparable to those obtained from molecular dynamics (MD) simulations, albeit with notable deviations in the under sampling of hairpin conformations and oversampling of extended configurations. Re-evaluation of existing data revealed an apparent weak correlation between NTB transition temperatures and bend angles, underscoring the complexity of molecular shapes beyond mere geometry. Furthermore, we integrated this conformational analysis into a pipeline of algorithmic molecular design, utilising a fragment-based genetic algorithm to generate novel cyanobiphenyl-containing materials. This integration opens new avenues for the exploration of liquid crystalline materials, particularly in systems where systematic conformer searches are impractical, such as large oligomeric systems. Our findings highlight the potential and growing importance of computational approaches in accelerating the design and synthesis of next-generation liquid crystalline materials.

‘Charge Reverse’ Halogen Bonding Contacts in Metal-Organic Multi-Component Compounds: Antiproliferative Evaluation and Theoretical Studies

Two new metal–organic multi-component compounds of Ni(II) and Co(II), viz. [Ni(3-CNpy)2(H2O)4]ADS·2.75H2O (1) and [Co(3-CNpy)2(H2O)4](4-ClbzSO3)2 (2) (3-CNpy = 3-cyanopyridine, ADS = anthraquinone-1,5-disulfonate, 4-ClbzSO3 = 4-chlorobenzenesulfonate), were synthesized and characterized using single crystal XRD, TGA, spectroscopic (IR, electronic) and elemental analyses. Both the compounds crystallize as multi-component compounds of Ni(II) and Co(II), with uncoordinated ADS and 4-ClbzSO3 moieties in the crystal lattice, respectively. Crystal structure analyses revealed the presence of antiparallel nitrile···nitrile and π-stacked assemblies involving alternate coordinated 3-CNpy and uncoordinated ADS and 4-ClbzSO3 moieties. Moreover, unconventional charge reverse Cl∙∙∙N halogen bonding contacts observed in compound 2 provide additional reinforcement to the crystal structure. Theoretical calculations confirm that the H-bonding interactions, along with anion–π(arene) and anion–π(CN) in 1 and π–π, antiparallel CN···CN and charge reverse Cl···N halogen bonds in 2, play crucial roles in the solid state stability of the compounds. In vitro anticancer activities observed through the trypan blue cell cytotoxicity assay reveal that the compounds induce significant concentration dependent cytotoxicity in Dalton’s lymphoma (DL) cancer cells, with nominal effects in normal healthy cells. Molecular docking studies reveal that the compounds can effectively bind with the active sites of anti-apoptotic proteins, which are actively involved in cancer progression.

Eliminating extracellular autoinducing peptide signals inhibits the Staphylococcus aureus quorum sensing agr system

An accessory gene regulator (agr) in the quorum sensing (QS) system in Staphylococcus aureus contributes to host infection, virulence factor production, and resistance to oxidative damage. Artificially maintaining the inactive state of agr QS impedes the host infection strategy of S. aureus and inhibits toxin production. The QS system performs intercellular signal transduction, which is activated by the mature autoinducer peptide (AIP). It is released from cells after AgrD peptide processing as an intercellular signal associated with increased bacterial cell density. This study evaluated the effectiveness of inhibiting agr QS wherein AIP trap carriers were made to coexist when culturing Staphylococcus aureus. Immersing a nitrocellulose (NC) membrane in Staphylococcus aureus ATCC 12600 culture inhibited QS-dependent α-hemolysin production, which significantly reduced the hemolysis ratio of sheep red blood cells by the culture supernatant. A quartz crystal microbalance analysis supported AIP adsorption onto the NC membrane. Adding the NC membrane during culture was found to maintain the expression levels of the agr QS gene agrA and α-hemolysin gene hla lower than that when it was not added. Eliminating extracellular AIP signals allowed agr QS to remain inactive and prevented QS-dependent α-hemolysin expression. Isolating intercellular signals secreted outside the cell is an effective strategy to suppress gene expression in bacterial cells that collaborate via intercellular signaling.