Spectroscopic sensing and quantification of AP-endonucleases using fluorescence-enhancement by cis–trans isomerization of cyanine dyes

Apurinic/apyrimidinic (AP) endonucleases are vital DNA repair enzymes, and proposed to be a prognostic biomarker for various types of cancer in humans. Numerous DNA sensors have been developed to evaluate the extent of nuclease activity but their DNA termini are not protected against other nucleases, hampering accurate quantification. Here we developed a new fluorescence enhancement (FE)-based method as an enzyme-specific DNA biosensor with nuclease-protection by three functional units (an AP-site, Cy3 and termini that are protected from exonucleolytic cleavage). A robust FE signal arises from the fluorescent cis–trans isomerization of a cyanine dye (e.g., Cy3) upon the enzyme-triggered structural change from double-stranded (ds)DNA to single-stranded (ss)DNA that carries Cy3. The FE-based assay reveals a linear dependency on sub-nanomolar concentrations as low as 10⁻¹¹ M for the target enzyme and can be also utilized as a sensitive readout of other nuclease activities.

Apurinic/apyrimidinic (AP) endonucleases are vital DNA repair enzymes, and proposed to be a prognostic biomarker for various types of cancer in humans.     

Influence of Moringa oleifera biodiesel–diesel–hexanol and biodiesel–diesel–ethanol blends on compression ignition engine performance,combustion and emission characteristics

In the current work, the influences of Moringa oleifera biodiesel–diesel–hexanol and Moringa oleifera biodiesel–diesel–ethanol blends on compression ignition engine characteristics were experimentally investigated. Experiments were conducted on a diesel engine at 0%, 25%, 50%, 75% and 100% load conditions run at a constant speed of 1500 rpm. The results revealed that B90-D5-H5 acquired the lowest BSFC and maximum BTE of 0.375 kg kW⁻¹ h⁻¹ and 28.8%, respectively, and B100 had the highest BSFC of 0.425 kg kW⁻¹ h⁻¹. B90-D5-H5 had the highest cylinder peak pressure of 74 bar at 4°CA aTDC. The maximum heat release rate (HRR) and longer ignition delay (ID) period of 44 J per °CA and 14.4°CA, respectively, were attained in the B90-D5-H5 blend. At 100% load condition, the lowest amount of carbon monoxide (CO) of 0.32% vol. was acquired in the B80-D5-E15 blend. The maximum nitric oxide (NO) emission of 1090 ppm was also acquired in the B80-D5-E15 blend. B100 had the lowest NO of 846 ppm; B80-D5-E15 had the lowest unburned hydrocarbon (UBHC) emission of 34 ppm at 100% load and the lowest smoke opacity of 34%. Biodiesel–diesel–alcohol blends improve engine performance and decrease emissions compared to the conventional diesel. The utilization of biodiesel–diesel–alcohol blends reduces the consumption of diesel. Hence, ethanol and hexanol are recommended as potential alternative additives in biodiesel–diesel blends to improve engine performance and reduce emissions.

In the current work, the influences of Moringa oleifera biodiesel–diesel–hexanol and Moringa oleifera biodiesel–diesel–ethanol blends on compression ignition engine characteristics were experimentally investigated.     

AIE and reversible mechanofluorochromism characteristics of new imidazole-based donor–π–acceptor dyes

Four new imidazole-based donor–π–acceptor 2a–2d dyes have been synthesized, and their solvatochromism, aggregation-induced emission (AIE) and mechanofluorochromic (MFC) properties were investigated. The new dyes 2a–2d were designed to have 1,4,5-triphenyl-1H-imidazole as an electron donor (D) and 1-indanone, 1,3-indandione, 2-phenylacetonitrile and 2-thiopheneacetonitrile as electron acceptors (A) linked through a phenyl bridge. The maximum absorption wavelength of 2a–2d dyes in DCM solution appeared at 376, 437, 368, and 375 nm, respectively. The dyes exhibit a high molar extinction coefficient (ε) and large Stokes shift, making them useful in optoelectronic applications. Solvatochromic properties of dyes 2a–2d have been studied and showed bathochromic changes in emission wavelengths, from 449 to 550 nm for 2a, 476 to 599 nm for 2b, 438 to 520 nm for 2c, and from 439 to 529 nm for 2d, as the solvent polarity increased from n-hexane to acetonitrile. Moreover, in dioxane/water mixture systems, AIE behaviors were observed, and the emission intensity of 2b–2d dyes increased by around 5, 3, and 3 times in the mixed solvent (dioxane : water = 10 : 90) in contrast to pure dioxane. In addition, the XRD data of the 2a–2d dyes in pristine, ground, and fumed states illustrate that the transition between the ordered crystalline and disordered amorphous phases is the primary cause of MFC behaviors mechanism. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) showed that the highest occupied molecular orbital (HOMO) of dyes is distributed on the donor unit. In contrast, the lowest unoccupied molecular orbital (LUMO) is mainly placed on the acceptor unit to reveal that the HOMO–LUMO transition has a great ICT character.

Four new imidazole-based donor–π–acceptor 2a–2d dyes have been synthesized, and their solvatochromism, aggregation-induced emission (AIE) and mechanofluorochromic (MFC) properties were investigated.     

Novel edaravone-based azo dyes: efficient synthesis,characterization, antibacterial activity,DFT calculations and comprehensive investigation of the solvent effect on the absorption spectra

The present study deals with designing and synthesizing novel dyes using the drug combination of edaravone and azo compounds which can be used as an indicator for anions and cations. The desired product synthesis was accomplished via a two-step process involving diazotizing the aromatic amines followed by the resultant salts coupling with edaravone. The resulting dyes were obtained with high yields under mild conditions. The structures of the dyes were identified with UV-vis, FT-IR, ¹H NMR and ¹³C NMR spectra and CHN analysis. To investigate the solvatochromism effect, the interaction of different solvents with the selected dyes was evaluated using several parameters including the dielectric constant, refractive index, hydrogen bond donating ability, hydrogen bond accepting ability and dipolarity/polarizability scale. To achieve deep understanding about the stability and geometrical characteristics of the azo–hydrazo tautomers of the synthesized dyes and their UV-visible spectra prediction, some DFT calculations were also carried out on the synthesized dyes. The antibacterial activities of some synthesized compounds were also evaluated using the disk diffusion method. The results revealed different activity of the selected synthesized dyes for antibacterial tests against selected Gram positive and Gram negative bacteria.

The present study deals with designing and synthesizing novel dyes using the drug combination of edaravone and azo compounds which can be used as an indicator for anions and cations.     

Tuning the fluorescence based on the combination of TICT and AIE emission of a tetraphenylethylene with D–π–A structure

A simple D–π–A structured tetraphenylethylene with two electron-rich methyloxy groups and two electron withdrawing cyano groups, which features both twisted intramolecular charge-transfer (TICT) and aggregation-induced emission (AIE) properties, namely TPEOMeCN has been prepared. The emission of TPEOMeCN examined in various solvents is dependent on the polarities of solvents, which indicates the TICT character. The emission intensity of the compound also enhances with the increasing water fraction in H₂O–DMSO mixtures, demonstrating the typical AIE property. Excitingly, the TICT and AIE emission could be observed separately or simultaneously by adjusting the water fraction or viscosity of the solvent. Encouragingly, the combined emission of the TPEOMeCN derived from this single molecule could be readily tuned via regulating the viscosity of the system, resulting in a broad emission peak which covers the visible spectrum (400–700 nm). This work provides a general strategy for designing molecules combining TICT emission and AIE for application as full-color emitters.

The combination of the TICT and AIE properties in a tetraphenylethylene based molecule with D–π–A structure is observed by simply adjusting the viscosity of the solvent.     

Adsorption behavior and mechanism of β-cyclodextrin–styrene-based polymer for cationic dyes

Cyclodextrin polymers are efficient adsorbents for dye adsorption. Herein, a β-cyclodextrin polymer (β-CDSP) with carboxyl groups and benzene rings was prepared via free radical polymerization of β-cyclodextrin-maleate and styrene. The adsorption performance of β-CDSP was studied by adsorbing neutral red (NR), basic fuchsin (BF) and safranine T (ST) dyes under different adsorption conditions (e.g., adsorption time, temperature and pH of the solution). The results showed that the adsorption of BF and ST was faster and better than that of NR. The adsorption kinetic behavior fitted well with both the pseudo-first-order and the pseudo-second-order models for NR and BF, but it fitted better with the latter for ST. The adsorption equilibrium data followed the Langmuir isotherm model. The adsorption process was endothermic and spontaneous, and a higher temperature was favorable for dye adsorption. Higher q_t values were obtained in a basic medium, which resulted from the electrostatic interactions between β-CDSP and cationic dyes. Furthermore, inclusion complexion and π–π interactions also contributed to the dye adsorption. The stability and reusability of β-CDSP were estimated by four regeneration cycles.

These figures show that the cyclodextrin polymer was synthesized successfully and possessed good thermal stability.     

Bain and Nishiyama–Wassermann transition path separation in the martensitic transitions of Fe

The importance of martensitic transformations has led to tremendous efforts to explore the microscopic martensitic transition paths. There are five possible transformation paths (for γ → α transition) known for Fe at present, and at an arbitrary activation energy, any of the five paths might be followed. It then becomes considerably difficult to monitor the microscopic phase transition mechanism in experiments. Therefore, it is helpful to realize only one of the paths in a physical process. Based on first-principles calculations, we show that at suitable activation energies the Nishiyama–Wassermann (N–W) transformation path can be realized without the involvement of the Bain path, since the condition E_NW(θ) < E < E_Bain can be satisfied by pure Fe. E is the activation energy of the system, and E_NW(θ) and E_Bain are the energy barriers for the N–W and Bain transformations, respectively. In particular, the potential energy surface (PES) for the N–W transformation has been calculated as being four-dimensional, i.e., E = E(a,b,c,θ), where (a, b, c) are the lattice constants and θ is the shear angle involved in the shear distortion of the N–W path.

The importance of martensitic transformations has led to tremendous efforts to explore the microscopic martensitic transition paths.     

A pillared-layered copper(i) halide-based metal–organic framework exhibiting dual emission,and piezochromic and thermochromic properties with a large temperature-dependent emission red-shift

We report a new copper halide-based compound [Cu₆I₆Br₂C₁₆H₃₂N₄] (1) with a 3D 2-fold interpenetrated framework structure. Upon excitation at 290 nm and 350 nm, compound 1 shows dual emission at ca. 500 nm and ca. 530 nm. As the temperature decreased from 300 K down to 6 K, the luminescent properties of compound 1 show large red shifts of 120 nm and 72 nm, respectively.

A pillared-layered copper(i) halide-based metal–organic framework [Cu₆I₆Br₂C₁₆H₃₂N₄] exhibiting dual emission, and piezochromic and thermochromic properties with a large temperature-dependent emission red-shift is reported.     

Structure,stability, absorption spectra and aromaticity of the singly and doubly silicon doped aluminum clusters AlnSim0/+ with n = 3–16 and m = 1, 2

Structures of the binary Al_nSi_m clusters in both neutral and cationic states were investigated using DFT and TD-DFT (B3LYP/6-311+G(d)) and (U)CCSD(T)/cc-pvTZ calculations. Silicon-doped aluminum clusters are characterized by low spin ground states. For small sizes, the Si dopant prefers to be located at vertices having many edges. For larger sizes, the Si atom prefers to be endohedrally doped inside an Al_n cage. Relative stability, adiabatic ionization energy and dissociation energies of each cluster size were evaluated. A characteristic of most Si doped Al clusters is the energetic degeneracy of two lowest-lying isomers. Calculated results confirm the high stability of the sizes Al₄Si₂, Al₁₂Si and Al₁₁Si₂⁺ as “magic” clusters, that exhibit 20 or 40 shell electrons and are thermodynamically more stable as compared to their neighbors. Electronic absorption spectra of isoelectronic magic clusters Al₁₃⁻, Al₁₂Si, and Al₁₁Si₂⁺ that have two pronounced bands corresponding to blue and violet lights, have been rationalized by using the electron shell model. The magnetically included ring current density (MICD) analyses suggest that they are also aromatic structures as a result of the “magic” 40 shell electrons.

The isoelectronic “magic” clusters with 40 shell electrons have enhanced thermochemical stability.      

TADF and exciplex emission in a xanthone–carbazole derivative and tuning of its electroluminescence with applied voltage

Materials showing white light emission have found applications in a variety of solid state devices especially in display technology. For white light emission, doping of red (R), green (G) and blue (B) emitters in a host matrix is commonly practised. However, finding RGB emitters of similar stability with homogenous doping is challenging. Furthermore, such devices suffer from color purity in the long run. Small organic light emitters, capable of colour tuning and having a broad emission spectrum are in high demand as they provide colour stability, reproducibility, a simple device geometry and high efficiency. Recently, it has been shown that the efficiency of OLEDs can be enhanced by employing thermally activated delayed fluorescence (TADF) materials. Here, we designed and synthesised a xanthone–carbazole based D-A-D material (Xan-Cbz) for TADF properties. Blue TADF emission, in neat thin films, at 470 nm was observed and further investigated by studying delayed fluorescence and lifetime measurements. In addition, a blend of Xan-Cbz with NPD shows exciplex emission at 525 nm in thin film. OLEDs based on Xan-Cbz were fabricated using several device configurations. OLEDs having the device configuration ITO/PEDOT:PSS/NPD/Xan-Cbz/Bphen/LiF-Al showed a luminance of 1.96 × 10⁴ Cd m⁻² (at a current density of 50 mA cm⁻²) and V_ON at ∼6 V. Electroluminescence showed the features of both neat emission (470 nm) of Xan-Cbz and its exciplex (525 nm) with NPD. Further, colour tuning was observed as a function of applied voltage and the ratio of light intensity (I₅₂₅/I₄₇₀) of neat and exciplex emission was found to decrease with increasing voltage. Greenish-blue emission (CIE coordinates: 0.202, 0.382) from Xan-Cbz OLEDs was obtained. Xan-Cbz showed its neat emission (at 470 nm) in ITO/PEDOT:PSS/CBP/Xan-Cbz/Bphen/LiF-Al and pure exciplex emission (at 525 nm) in ITO/PEDOT:PSS/NPD:Xan-Cbz/Bphen/LiF-Al device configurations. Thus in this article we showed blue TADF emission, exciplex emission and voltage dependent color tuning in OLEDs based on a small organic emitter.

Xanthone–carbazole (Xan–Cbz) derivative is synthesized and its photophysical properties are explored. OLEDs of Xan–Cbz shows tunability of electro-luminescence with applied voltage.     

Binding interactions and FRET between bovine serum albumin and various phenothiazine-/anthracene-based dyes: a structure–property relationship

The present study demonstrates binding interactions and Förster resonance energy transfer (FRET) between bovine serum albumin (BSA) and a series of structurally and electronically diverse phenothiazine (PTZ) and anthracene (ANT) dyes. Upon selective excitation of tryptophan (Trp) residues of BSA, radiationless energy transfer to a dye takes place, resulting in fluorescence quenching of the former. Fluorescence quenching mechanisms, FRET parameters, possible locations, and binding constants of dyes with the BSA have been examined to deduce a structure–property relationship. The mechanism of quenching is apparently static in nature. PTZ dyes with heteroatoms and a pentyl tail (C5-PTZ) attached to them were found to have a stronger binding affinity with BSA as compared to ANT dyes. Stronger binding affinities of C5-PTZ dyes with BSA result in greater energy transfer efficiencies (E_T). A dye with a strong electron-withdrawing group present in it has shown better energy accepting capability. A FRET study with dicyanoaniline (DCA) analogs of PTZ and ANT dyes (C5-PTZDCA and ANTDCA, respectively) revealed that E_T depends on electronic and structural factors of molecules. An almost orthogonal geometry between ANT and DCA moieties (∼79°) in ANTDCA induces the greater extent of electron transfer from ANT to DCA, showing a higher E_T for this dye as compared to C5-PTZDCA in which the torsion angle is only ∼38°. Further, the observed facts have been validated by experimentally determined bandgaps (using cyclic voltammetry experiments) for all the dyes. Thus, the hydrophobic character and the presence of interactive substituents along with the electron-accepting abilities majorly control the FRET for such dyes with BSA.

The present study demonstrates binding interactions and Förster resonance energy transfer (FRET) between bovine serum albumin (BSA) and a series of structurally and electronically diverse phenothiazine (PTZ) and anthracene (ANT) dyes.     

Microstructure,friction and corrosion resistance properties of a Ni–Co–Al2O3 composite coating

Ni–Co–Al₂O₃ composite coatings were prepared by pulsed electrodeposition and electrophoresis–electrodeposition on aluminum alloy. The content of Al₂O₃ particles of the Ni–Co–Al₂O₃ composite coating prepared by electrophoresis–electrodeposition was significantly higher than the composite coating prepared by pulsed electrodeposition. The composite coating prepared by electrophoresis–electrodeposition exhibited a better anti-wear performance than that prepared by pulsed electrodeposition. The morphology, composition and microstructure of the composite coatings were determined by means of X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The hardness and friction properties of the samples were tested on the microhardness tester and the friction and wear loss tester respectively.

Ni–Co–Al₂O₃ composite coatings were prepared by pulsed electrodeposition and electrophoresis–electrodeposition on aluminum alloy.     

Electrospinning preparation and near-infrared absorption properties of a silica/cesium tungsten bronze micro–nano fiber membrane

Silica/cesium tungsten bronze (SiO₂/Cs_xWO₃) composite micro–nano fiber membranes were prepared by the co-precursor electrostatic spinning method using cesium chloride, tungsten powder and tetraethyl orthosilicate as raw materials. TGA, XRD, FT-IR, XPS, SEM and ultraviolet-visible-near red spectrophotometry were used to analyze the thermal decomposition process, phase composition, microscopic morphology and near-infrared absorption properties of the product. Studies have shown that as the ratio of Cs/W of raw materials increases, the crystallinity of Cs_xWO₃ in the product increases first and then decreases. When n(Cs)/n(W) reaches 0.5, its crystallinity is the most complete; similarly, calcination also contributes to the crystallization of Cs_0.33WO₃, but high temperatures above 800 °C will also destroy its crystal structure. The study found that after calcination at 700 °C, the fiber membrane with a Cs/W atomic ratio of 0.5 has the best infrared absorption performance. The average absorbance of near-infrared light at 780–2500 nm is 1.5, which is 5.56 times that of the pure SiO₂ fiber membrane. The tensile strength reaches 2.4 MPa, which can meet practical requirements. This research provides a basis for the development of flexible solar shading materials under complex outdoor conditions.

A silica/cesium tungsten bronze composite fiber membrane with good near-infrared shielding performance is prepared by electrostatic spinning, and can be used for solar heat insulation.     

A facile synthesis of a cobalt nanoparticle–graphene nanocomposite with high-performance and triple-band electromagnetic wave absorption properties

Ferromagnetic metal nanoparticle/graphene nanocomposites are promising as excellent electromagnetic (EM) wave absorption materials. In this work, we used a facile method to synthesize a cobalt nanoparticle–graphene (CoNP–G) nanocomposite. The obtained CoNPs–G exhibited a saturation magnetization (M_s) of 31.3 emu g⁻¹ and a coercivity (H_C) of 408.9 Oe at 298.15 K. In particular, the CoNPs–G nanocomposite provided high-performance EM wave absorption with multiband, wide effective absorption bandwidth, which was mainly attributed to the synergy effects generated by the magnetic loss of cobalt and the dielectric loss of graphene. In the range of 2–18 GHz, the sample (55 wt% CoNPs–G) held three effective reflection loss (RL) peaks (frequency ranges of 2.4–3.84, 7.84–11.87 and 13.25–18 GHz, respectively, RL ≤ −10 dB) with the coating thickness of 4.5 mm, and the effective bandwidth reached the maximum of 10.22 GHz, and the minimal RL reached −40.53 dB at 9.50 GHz. Therefore, the CoNPs–G nanocomposite presents a great promising application in the electromagnetic wave absorption field.

Ferromagnetic metal nanoparticle/graphene nanocomposites are promising as excellent electromagnetic (EM) wave absorption materials.     

An organic–inorganic hybrid nanomaterial composed of a Dowson-type (NH4)6P2Mo18O62 heteropolyanion and a metal–organic framework: synthesis,characterization, and application as an effective adsorbent for the removal of organic dyes

In this work, an inorganic–organic hybrid nanomaterial, P₂Mo₁₈/MIL-101(Cr), based on Wells–Dawson-type (NH₄)₆P₂Mo₁₈O₆₂ polyoxometalate (abbreviated as P₂Mo₁₈) and the MIL-101(Cr) metal–organic framework was fabricated by the reaction of (NH₄)₆P₂Mo₁₈O₆₂, Cr(NO₃)₃·9H₂O and terephthalic acid under hydrothermal conditions. The as-prepared recyclable nanohybrid was fully characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) equipped with energy dispersive X-ray microanalysis (EDX), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy and Brunauer–Emmett–Teller (BET) specific surface area studies. All the analyses confirmed the successful insertion of P₂Mo₁₈O₆₂⁶⁻ heteropolyanion within the cavities of MIL-101(Cr). The encapsulated MIL-101(Cr) showed a considerable decrease in both pore volume and surface area compared with MIL-101(Cr) due to incorporation of the very large Dowson-type polyoxometalate into the three-dimensional porous MIL-101(Cr). The nanohybrid had a specific surface area of 800.42 m² g⁻¹. The adsorption efficiency of this nanohybrid for removal of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) from aqueous solutions was evaluated. Surprisingly, the composite not only presented a high adsorption capacity of 312.5 mg g⁻¹ for MB, but also has the ability to rapidly remove 100% MB from a dye solution of 50 mg L⁻¹ within 3 min. These results confirmed that this adsorbent is applicable in a wide pH range of 2–10. The nanohybrid showed rapid and selective adsorption for cationic MB and RhB dyes from MB/MO, MB/RhB, MO/RhB and MB/MO/RhB mixed dye solutions. The equilibrium adsorption data were better fitted by the Langmuir isotherm. Kinetics data indicate that the adsorption of the dye follows a pseudo-second order kinetics model. Also, this material could be effortlessly separated and recycled without any structural modification. Accordingly, it is an efficient adsorbent for removing cationic dyes.

An MIL-101(Cr) metal–organic framework nanocomposite containing P₂Mo₁₈O₆₂⁶⁻ polyanions was prepared and applied as an ultrafast adsorbent to remove organic dyes from water.     

Structural evolution,photoelectron spectra and vibrational properties of anionic GdGen− (n = 5–18) nanoalloy clusters: a DFT insight

The structural growth of Gd-doped germanium anionic nanoclusters, GdGe_n⁻ (n = 5–18), has been explored via quantum chemistry calculations using the mPW2PLYP method and an unprejudiced structural searching technique known as ABCluster. The optimized geometries exhibited that when n = 10–14, the structural evolution favors the Gd-linked configuration where the Gd atom as a connector bridges two Ge subgroups, while the Gd atom is encapsulated in a closed cage-like Ge frame when n = 15–18. The properties like magnetic moment, charge transfer, relative stability, HOMO–LUMO gap, photoelectron spectra, and infrared and Raman spectra have been predicted. The information of these spectra could provide extra approaches to experimentally determine the electronic structures and equilibrium configuration of these compounds. The largest spin magnetic moment of 7 μ_B is attained via half-filled 4f states. The GdGe₁₆⁻ nanocluster is determined to be a superatom because its total valence of 75 electrons can be distributed to the orbital sequence of 1S²1P⁶(4f⁷)1D¹⁰1F¹⁴2S²2P²1G¹⁸2P⁴2D¹⁰, which complies with not only Hund''s rule, but also the spherical jellium model. Particularly, its UV-Vis spectra match well with solar energy distribution. Such materials act as nano multifunctional building units potentially used in solar energy converters or ultra-highly sensitive near-infrared photodetectors.

The structural evolution, electronic and vibrational properties of GdGe_n⁻ (n=5-18) nanoclusters were studied by quantum chemical calculations, which revealed GdGe₁₆⁻ nanocluster is a superatom to the orbital of 1S²1P⁶(4f⁷)1D¹⁰1F¹⁴2S²2P²1G¹⁸2P⁴2D¹⁰.     

Theoretical calculation of a full-dimensional ab initio potential energy surface and prediction of infrared spectra for Xe–CS2

An effective four-dimensional (4D) ab initio potential energy surface (PES) for Xe–CS₂ which explicitly involves the intramolecular Q₁ symmetric stretching and Q₃ antisymmetric stretching vibrational coordinates of CS₂ is constructed. The computations are carried out employing single- and double-excitation coupled-cluster theory with a non-iterative perturbation treatment of triple excitations [CCSD(T)] method with a large basis set. Two vibrationally averaged potentials at the ground and ν₁ + ν₃ (ν₁ = 1, ν₃ = 1) excited states are obtained by integrating the 4D potentials over the Q₁ and Q₃ coordinates. The potentials have a T-shaped global minimum and two equivalent linear local minima. The radial discrete variable representation/angular finite basis representation and the Lanczos algorithm are employed to calculate the rovibrational energy levels for Xe–CS₂. The infrared band origin shift associated with the fundamental band of CS₂ is predicted, which is red-shifted by −1.996 cm⁻¹ in the ν₁ + ν₃ region. In addition, we further predict the spectroscopic parameters for the ground and the ν₁ + ν₃ excited states of Xe–CS₂. Compared with the previous Rg–CS₂ (Rg = He, Ne, Ar, Kr) complexes, we found that the complexes of the rare gas atoms with CS₂ display obvious regularities.

Contour plot (in cm⁻¹) of the averaged intermolecular potential energy surface for Xe–CS₂ with CS₂ at the ν₁ + ν₃ excited state.     

Synthesis,structure, and fluorescence properties of a calcium-based metal–organic framework

The solvothermal reaction of a mixture of calcium acetylacetonate and 1,4-naphthalenedicarboxylic acid (H₂NDC) in a solution containing ethanol and distilled water gave rise to a metal–organic framework (MOF), {(H₃O⁺)₂[Ca(NDC)(C₂H₅O)(OH)]}₄·1.1H₂O. This MOF possesses a new structure composed of calcium clusters and H₂NDC linker anions and shows a unique fluorescence property; it exhibits a fluorescence peak at 395 nm (λ_ex = 350 nm) at room temperature, which is blue-shifted compared with that exhibited by the free H₂NDC ligand. One of the possible mechanisms for this fluorescence is likely attributable to a ligand-to-metal charge transfer (LMCT) transition and is the first example of a calcium-based MOF exhibiting blue-shifted fluorescence due to LMCT.

The solvothermal reaction of a mixture of calcium acetylacetonate and 1,4-naphthalenedicarboxylic acid (H₂NDC) in a solution containing ethanol and distilled water gave rise to a metal–organic framework (MOF), {(H₃O⁺)₂[Ca(NDC)(C₂H₅O)(OH)]}₄·1.1H₂O.     

Green synthesis of biocompatible core–shell (Au–Ag) and hybrid (Au–ZnO and Ag–ZnO) bimetallic nanoparticles and evaluation of their potential antibacterial,antidiabetic, antiglycation and anticancer activities

The fabrication of bimetallic nanoparticles (BNPs) using plant extracts is applauded since it is an environmentally and biologically safe method. In this research, Manilkara zapota leaf extract was utilized to bioreduce metal ions for the production of therapeutically important core–shell Au–Ag and hybrid (Au–ZnO and Ag–ZnO) BNPs. The phytochemical profiling of the leaf extract in terms of total phenolic and flavonoid content is attributed to its high free radical scavenging activity. FTIR data also supported the involvement of these phytochemicals (polyphenols, flavonoids, aromatic compounds and alkynes) in the synthesis of BNPs. Whereas, TEM and XRD showed the formation of small sized (16.57 nm) spherical shaped core–shell Au–Ag BNPs and ZnO nano-needles with spherical AuNPs (48.32 nm) and ZnO nano-rods with spherical AgNP (19.64 nm) hybrid BNPs. The biological activities of BNPs reinforced the fact that they show enhanced therapeutic efficacy as compared to their monometallic components. All BNPs showed comparable antibacterial activities as compared to standard tetracycline discs. While small sized Au–Ag BNPs were most effective in killing human hepato-cellular carcinoma cells (HepG2) in terms of lowest cell viability, highest intracellular ROS/RNS production, loss of mitochondrial membrane potential, induction of caspase-3 gene expression and enhanced caspase-3/7 activity. BNPs also effectively inhibited advanced glycation end products and carbohydrate digesting enzymes which can be used as a nano-medicine for aging and diabetes. The most important finding was the permissible biocompatibility of these BNPs towards brine shrimp larvae and human RBCs, which suggests their environmental and biological safety. This research study gives us insight into the promise of using a green route to synthesize commercially important BNPs with enhanced therapeutic efficacy as compared to conventional treatment options.

Graphical demonstartion of the Manikara zapota-mediated biosynthesis of Bimetallic nanoparticles (BNPs) and evalution of their biological activities.