Fluorescence Studies Research Articles

Divergent Total Synthesis of Isoflavone Natural Products and Their Potential as Therapeutic Agents for TTR Amyloidosis.

We have achieved the divergent total synthesis of nine isoflavone natural products 1-9 starting from commercially available 2,4,6-trihydroxyacetophenone as a starting material. The isoflavone skeleton of 1-9 was constructed by the Suzuki-Miyaura coupling reaction as the key reaction. Investigation of the potential of 1-9 as therapeutic agents for transthyretin (TTR) amyloidosis revealed that millexatin F (3) showed the best efficacy in ex vivo competitive binding experiments and thioflavin-T fluorescence studies. Therefore, millexatin F (3) is promising as a seed compound for a novel TTR amyloidosis therapeutic agent.

Photoinduced Stereoselective Giese Addition on Coumarins

AbstractDiastereoselective Giese addition on coumarin-3-carboxylate bearing a chiral auxiliary with N-hydroxyphthalimide ester to generate the corresponding alkylated adduct has been explored. Among screened chiral auxiliaries, bulkier one with appropriate steric hindrance is better for diastereoselective addition. Mechanistic studies involving fluorescence studies and On/Off experiments shed insight onto the plausible reaction pathway.

Unveiling the Ultrafast Excitation Energy Transfer in Tetraarylpyrrolo[3,2-b]pyrrole-BODIPY Dyads.

We have synthesized two dyads (dyad 1 and 2) comprising of tetraarylpyrrolo[3,2-b]pyrrole (TAPP) and BODIPY. In dyad 1, two BODIPYs are directly connected with TAPP moiety whereas in dyad 2, BODIPYs are connected through phenylethynyl linkers. TAPP is a blue energy donor which is easy to synthesize and functionalize as compared to other well-known blue energy donors like pyrene, perylene etc. This is the first report of using TAPP as an energy donor in BODIPY based dyad molecules. Complete quenching of TAPP fluorescence in the dyads suggests fast energy transfer from TAPP to BODIPY unit (ETE ~ 99.9%). Ultrafast fluorescence and transient absorption spectroscopic studies of dyad 1 showed TAPP to BODIPY energy transfer in 125 fs (kET = 8.0 x 1012 s-1) which is one of the fastest energy transfer events in BODIPY based dyad reported so far. Whereas, in dyad 2, energy transfer is almost four times slower (480 fs, kET = 2.1 x 1012 s-1). These results were rationalized by theoretical Förster formulations. This study shows that suitably matched optical properties of TAPP and BODIPY dyes along with their easy syntheses will be the key to develop highly efficient energy transfer systems in future for multiple applications.

Space‐ and Time‐resolved Emission Features of Micro‐ and Nano‐sized Perylene‐based Zr Metal‐Organic Frameworks

AbstractWhile many photoresponsive metal‒organic frameworks (MOFs) have been reported to date, finding applications in several technologically relevant fields such as photocatalysis, sensors, and light‐emitting devices, significantly scarcer are the reports addressing the relationship between the MOFs emissive features and their crystalline domain size (i.e., micro‐ and nano‐sized materials). Herein, a valuable contribution is offered to this issue which consists of the use of reticular chemistry to prepare a Zr‐MOF featuring spatially separated tetracarboxylated‐functionalized perylenes as ligand. Single crystal X‐ray analysis of such Zr‐MOF revealed the formation of micro‐ and meso‐porous channels. The perylene‐based Zr‐MOF exhibited notable optoelectronic features, including a relatively small optical bandgap of 1.82 eV and emission features different from that of the constituting perylene ligand in the solid state. Additionally, local probe techniques are used to unveil the emission properties of isolated Zr‐MOF crystals. Space‐ and time‐resolved fluorescence studies revealed a strong dependence of the emissive features of the Zr‐MOF, both in terms of its intensity and lifetime, to the crystalline domain size.

Targeting Human Papillomavirus 33 E2 DNA Binding Domain With Polyphenols: Unveiling Interactions Through Biophysical and In Silico Methods.

The human papillomavirus (HPV) 33 is a high-risk strain that causes lesions with potential cancerous outcomes. Its E2 protein regulates the viral protein transcription and life cycle maintenance. The DNA binding domain (DBD) of the E2 protein plays a crucial role in the viral life cycle. The DBD region of the E2 protein is particularly interesting for targeting and finding potential inhibitors to inhibit its function or dimerization. Given the limited research on HPV 33 and its proteins, the present work delved into the interaction of two natural polyphenolic compounds, resveratrol, and baicalein, with the E2 DBD of HPV 33 using biophysical and in silico studies. Fluorescence studies of the E2 DBD-polyphenol complexes showed fluorescence quenching with a binding constant of the order of 106 M-1. Circular dichroism data reveal conformational changes upon binding with the polyphenols, possibly due to distinct binding sites of the E2 DBD. Differential scanning calorimetry exhibited higher melting temperatures for the two complexes than alone DBD, suggesting the complexes' stability. ITC experiment suggested favorable binding reactions with kd values in the micromolar range. Molecular docking and dynamic simulation studies revealed that the resveratrol binds to the helical region and baicalein near the central dimeric interface of E2 DBD with a good binding affinity, forming a stable protein-ligand complex during the run of 100 ns simulation. Therefore, the current study identifies both polyphenolic compounds as promising candidates for potential antiviral drug development.

De-etiolation is Almost Colour Blind: the Study of Photosynthesis Awakening Under Blue and Red Light.

The synthesis and assembly of functioning photosynthetic complexes in chloroplasts developing from etioplasts during the de-etiolation of angiosperm seedlings are imperative for the plant's autotrophic lifestyle. This study compared de-etiolation process under monochromatic red or blue light of equal photon flux density during a 24-hour illumination period of etiolated Arabidopsis seedlings. The aim was to elucidate the impact of these light wavelength on the etioplast-to-chloroplast transformation and the initiation of light-dependent photosynthetic reactions. Both treatments lead to the formation of functional young chloroplasts; however, the etioplast-to-chloroplast transition and the assembly of photosynthetic complexes occurred unevenly, with individual steps tuned by red or blue light. Ultrastructural analysis suggested faster prolamellar bodies disassembly under blue light, while low temperature fluorescence studies indicated a slower transformation of protochlorophyllide to chlorophyllide, and chlorophyll a, under these conditions. Red light further promoted the synthesis of chlorophyll b and LHCII antenna proteins. However, the efficiency of antennae in dissipating excess absorbed energy was higher for seedlings de-etiolated under blue light; the maximum quantum yield of the photosystem II reached 0.81 after 24-hour de-etiolation, equivalent to mature plants. Blue light seemed to enhance the development of well-functioning photosystems (I and II) and antennae. These findings are important for gaining a deeper understanding of photoreceptor regulation of de-etiolation and for utilizing selected light regimes to improve crop yield.

ATRP with ppb Concentrations of Photocatalysts.

In atom transfer radical polymerization (ATRP), dormant alkyl halides are intermittently activated to form growing radicals in the presence of a CuI/L/X-CuII/L (activator/deactivator) catalytic system. Recently developed very active copper complexes could decrease the catalyst concentration to ppm level. However, unavoidable radical termination results in irreversible oxidation of the activator to the deactivator species, leading to limited monomer conversions. Therefore, successful ATRP at a low catalyst loading requires continuous regeneration of the activators. Such a regenerative ATRP can be performed with various reducing agents under milder reaction conditions and with catalyst concentrations diminished in comparison to conventional ATRP. Photoinduced ATRP (PhotoATRP) is one of the most efficient methods of activator regeneration. It initially employed UV irradiation to reduce the air-stable excited X-CuII/L deactivators to the activators in the presence of sacrificial electron donors. Photocatalysts (PCs) can be excited after absorbing light at longer wavelengths and, due to their favorable redox potentials, can reduce X-CuII/L to CuI/L. Herein, we present the application of three commercially available xanthene dyes as ATRP PCs: rose bengal (RB), rhodamine B (RD), and rhodamine 6G (RD-6G). Even at very low Cu catalyst concentrations (50 ppm), they successfully controlled PhotoATRP. Well-defined polymers with preserved livingness were prepared under green LED irradiation, with subppm concentrations ([PC] ≥ 10 ppb) of RB and RD-6G or 5 ppm of RD. Interestingly, these PCs efficiently controlled ATRP at wavelengths longer than their absorption maxima but required higher loadings. Polymerizations proceeded with high initiation efficiencies, yielding polymers with narrow molecular weight distributions and high chain-end fidelity. UV-vis, fluorescence, and laser flash photolysis studies helped to elucidate the mechanism of the processes involved in the dual-catalytic systems, comprising parts per million of Cu complexes and parts per billion of PCs.

Flavones Suppress Aggregation and Amyloid Fibril Formation of Human Lysozyme under Macromolecular Crowding Conditions.

The crowded milieu of a biological cell significantly impacts protein aggregation and interactions. Understanding the effects of macromolecular crowding on the aggregation and fibrillation of amyloidogenic proteins is crucial for the treatment of many amyloid-related disorders. Most in vitro studies of protein amyloid formation and its inhibition by small molecules are conducted in dilute buffers, which do not mimic the complexity of the cellular environment. In this study, we used PEGs to simulate macromolecular crowding and examined the inhibitory effects of flavones DHF, baicalein, and luteolin on human lysozyme (HuL) aggregation at pH 2. Naturally occurring flavones have been effective inhibitors of amyloid formation in some proteins. Our findings indicate that while flavones inhibit HuL aggregation and fibrillation in dilute buffer solutions, complete inhibition is observed with a combination of flavones and PEGs, as shown by ThT fluorescence, light scattering, TEM, and AFM studies. The species formed in the presence of PEG 8000 and flavones were less hydrophobic, less toxic, and α-helix-rich compared to control samples, which were hydrophobic and β-sheet-rich, as demonstrated by ANS hydrophobicity, MTT assay, and CD spectroscopy. Fluorescence titration studies of flavones with HuL showed a significant increase in binding constant values under crowding conditions. These findings highlight the importance of macromolecular crowding in modulating protein aggregation and amyloid inhibition. Further studies using disease-causing mutants of HuL and other amyloidogenic proteins are needed to explore the role of macromolecular crowding in small-molecule-mediated modulation and inhibition of protein aggregation and amyloid formation.

Optogenetic Control of the Mitochondrial Protein Import in Mammalian Cells.

Mitochondria provide cells with energy and regulate the cellular metabolism. Almost all mitochondrial proteins are nuclear-encoded, translated on ribosomes in the cytoplasm, and subsequently transferred to the different subcellular compartments of mitochondria. Here, we developed OptoMitoImport, an optogenetic tool to control the import of proteins into the mitochondrial matrix via the presequence pathway on demand. OptoMitoImport is based on a two-step process: first, light-induced cleavage by a TEV protease cuts off a plasma membrane-anchored fusion construct in close proximity to a mitochondrial targeting sequence; second, the mitochondrial targeting sequence preceding the protein of interest recruits to the outer mitochondrial membrane and imports the protein fused to it into mitochondria. Upon reaching the mitochondrial matrix, the matrix processing peptidase cuts off the mitochondrial targeting sequence and releases the protein of interest. OptoMitoImport is available as a two-plasmid system as well as a P2A peptide or IRES sequence-based bicistronic system. Fluorescence studies demonstrate the release of the plasma membrane-anchored protein of interest through light-induced TEV protease cleavage and its localization to mitochondria. Cell fractionation experiments confirm the presence of the peptidase-cleaved protein of interest in the mitochondrial fraction. The processed product is protected from proteinase K treatment. Depletion of the membrane potential across the inner mitochondria membrane prevents the mitochondrial protein import, indicating an import of the protein of interest by the presequence pathway. These data demonstrate the functionality of OptoMitoImport as a generic system with which to control the post-translational mitochondrial import of proteins via the presequence pathway.

Synthesis and study of bistriazolyl-pyrazines as new ligands for An/Ln separations

Herein, we present new hydrophilic tridentate ligands, bistriazolyl pyrazines. Their design was inspired by structurally similar and promising bis-triazolyl-pyridines (PyTri) ligands as well as theoretically derived criteria for the design of tridentate ligands for An/Ln separations suggested by theoretical studies. These ligands have been synthesised, characterised and tested as possible extractants for An/Ln nuclear separations. In addition, UV and fluorescence studies, pKa determination, and crystallographic and theoretical studies have been performed to explain their observed behaviour. Although the results of the solvent extraction studies have shown that these ligands do not possess sufficient selectivity for the extraction of Am vs Eu in i-SANEX conditions, this study presents a valuable test of the criteria for the design of tridentate heterocyclic N-donor ligands for advanced nuclear separation as postulated by theoretical studies a decade ago. Our experimental observations and theoretical studies have found that these criteria might not be the best guidance for designing novel hydrophilic ligands for An/Ln separations in i-SANEX conditions.

Optical, electrical, structural properties by of PFO-PMMA films loaded with TiO2 nanoparticles

The authors studied Poly (methyl methacrylate) also called PMMA films with different concentrations of Poly (9, 9′-di-n-octylfuorenyl-2, 7-diyl) also called PFO and concluded that 1% PFO blended with PMMA is the best choice for opto-electronic applications. In the present study, the authors prepared nanocomposite films of PMMA + 1% PFO + different concentrations of TiO2 nanoparticles. The resulting films were subjected to FTIR, XRD, UV–visible, fluorescence and electrical conductivity studies. The polymer matrix undergoes modifications in its molecular and microstructural characteristics as evidenced by FTIR and XRD results. The addition of TiO2 nanoparticles leads to a uniform dispersion and good interaction with the blend matrix resulting in homogeneous films. The additional peaks were found at a wavenumber of 3620 cm−1 in FTIR can be attributed to stretching vibration of TiO2. The presence of TiO2 nanoparticles is confirmed by the distinctive diffraction peaks observed at 25.4°, 37.8°, 48.3°, 54.3°, 55.2°, and 62.8°. With a shift in the absorption peak towards higher wavelengths, the nanocomposites show greater absorption in the UV and visible regions. As the concentration of TiO2 increases, the optical parameters such as absorption coefficient, extinction coefficient, Urbach energy, refractive index and optical conductivity also increase. The direct optical band gap of the PNC films decreases from 5.03 to 3.06 eV and indirect band gap decreases from 4.52 to 1.92 eV at 10 wt% of TiO2 concentration. The addition of TiO2 nanoparticles to the PFO/PMMA matrix resulted in an increase in fluorescence emission intensity. The AC electrical conductivity exhibits increasing trend with frequency in Audio-Frequency range. Thus TiO2 nanoparticles improve the overall optical, electrical, and structural properties of PFO-PMMA nanocomposites. This means that they can be used in a variety of optoelectronic and advanced optical devices.

Variations of the elemental composition distribution over the thickness of YBa2Cu3O7-δ thin films obtained by pulsed laser deposition from one target

Epitaxial YBa2Cu3O7‒δ (YBCO) films 150-200 and 300 nm thick, respectively, were deposited on SrTiO3 (100) substrates by pulsed laser deposition at different conditions: with and without using the velocity filtration technique. The films have T(R=0) in the range of 77.4 - 87 R(T) depending on the conditions of deposition from one target with YBa2Cu3O6.8 composition. The films contain Zn, Sr, Pd, Ag and Ti impurity elements obtained from the target (a total of no more than 2 at. % ). Data of the film resistance temperature dependences, X-ray phase analysis, analysis of X-ray fluorescence (XRF) spectra and study of the surface relief by SEM methods revealed the nonuniform distributions of impurity and matrix Y, Ba, Cu elements over the film depth. Impurity concentrations near the surface lead to the formation of faceted spiral pyramids on the surface, which probably evolve into large elongated particles according to the Ostwald mechanism. This knowledge is practically important for optimizing pulsed laser deposition technologies and creating 2D instruments and devices for studying physical phenomena.

Designing of amiloride loaded citrate functionalized amorphous silica nanoparticles to investigate its genotoxic and cytotoxic potential

In the present work, silica-based nanocarrier for the anticancer drug, amiloride have been synthesized and characterized using various physicochemical techniques. The aim of this work emphasis on investigating the physicochemical properties and cytotoxic effects of citrate-functionalized amiloride loaded silica nanoparticles. Silica nanoparticles synthesis was carried out via condensation reaction, then coated by tris sodium citrate, followed by their functionalization using amiloride through EDC-NHS reaction. SEM and HR-XRD analysis indicated the formation of amorphous spherical silica nanoparticles. The existence of citrate coating was evident from FT-IR and TGA results, which were supported by DLS and zeta potential studies. The formation of amiloride conjugated citrate coated silica nanoparticles (SiNPs-Cit@Ami) was confirmed by the DLS, Zeta potential and UV-Visible spectroscopy. Size of SiNPs-Cit@Ami nanoparticles was found to be around 80nm using TEM. Additionally, these nanoparticles showed high loading efficiency and time-dependent release of amiloride. DNA binding studies were examined using UV–Visible, Fluorescence spectroscopic and Competitive fluorescence studies. The results indicate that SiNPs-Cit@Ami bind to Ct-DNA via minor groove binding mode. Furthermore, the cytotoxic effect of SiNPs-Cit@Ami on HepG2 cell lines was found to be higher than amiloride alone. Our findings suggest that SiNPs-Cit@Ami can be employed as a promising candidate for cancer mitigation.

Acylhydrazone Bond: A Pivotal Bridge for Modifying Julolidine Derivative with Pyrazole Group as MultiStimuli‐Responsive Fluorescent Materials

AbstractTo screen julolidine derivatives containing a pyrazole group with excellent fluorescence properties and promising applications in multistimuli‐responsive fluorescent materials, three novel compounds were designed and synthesized by connecting pyrazoles through typical conjugated bonds: imine (T1), dihydrazone (T2), and acylhydrazone (T3). The molecular structure of the title compounds was characterized by 1H NMR, 13C NMR, and HR‐MS. The representative compound T3 was verified by single crystal X‐ray diffraction. Although the three compounds have roughly similar conjugated structures, dissimilarity in their fluorescence properties was apparent. The results of fluorescence studies showed that the compound T3, which was connected to julolidine and pyrazole by an acylhydrazone bond, exhibited excellent fluorescence performance compared to the other compounds T1 and T2. Compound T3 can also respond to external stimuli, such as solvent viscosity, organic acids/bases, and mechanical forces. In addition, T3 could also specifically detect Cu2+ ions, and the fluorescence titration data indicated that the low limit of detection (LOD) of compound T3 for Cu2+ is 0.26 µM within the range from 0 to 50 µM. Therefore, this work provides a preliminary basis for the development of multistimuli‐responsive fluorescent molecular materials containing acylhydrazone fragment.

Exopolysaccharides from the Green Microalga Strain Coelastrella sp. BGV-Isolation, Characterization, and Assessment of Anticancer Potential.

Algal metabolites have been extensively studied as potential anticancer therapeutics. Among them, polysaccharides have attracted much attention because of their beneficial biological effects and safety. In the present research, the chemical characteristics, antitumor, and proapoptotic activities of extracellular polysaccharides (EPS) isolated from a new Bulgarian strain of the green microalga Coelastrella sp. BGV were investigated. A fast and convenient method of precipitation with cold ethanol was used to isolate EPS from the culture medium. The chemical characteristics of the isolated EPS were examined by colorimetric and spectrophotometric analyses, HPSEC-RID and HPLC-UV chromatography, and FT-IR spectroscopy. The results showed that the isolated EPS sample consists of three carbohydrate fractions with different molecular weights (11.5 × 104 Da, 30.7 × 104 Da, and 72.4 × 104 Da, respectively) and contains 7.14 (w/w%) protein. HPLC-UV analysis revealed the presence of galactose and fucose. The total uronic acid content in the sample was 4.5 (w/w%). The IR-FT spectrum of EPS revealed the presence of various functional groups typical of a polysaccharide (or proteoglycan) composed primarily of neutral sugars. The anticancer potential of the obtained EPS was assessed using cell lines with cancerous and non-cancerous origins as in vitro experimental models. The results of the performed MTT assay showed that EPS reduced the viability of the cervical and mammary carcinoma cell lines HeLa and MCF-7, while the control non-cancer cell lines BALB/3T3 and HaCaT were less affected. The HeLa cell line showed the highest sensitivity to the effects of EPS and was therefore used for further studies of its anticancer potential. The ability of EPS to inhibit cancer cell migration was demonstrated by wound-healing (scratch) assay. The cell cycle FACS analysis indicated that the EPS treatment induced significant increases in the sub G1 cell population and decreases of the percentages of cells in the G1, S, and G2-M phases, compared to the control. The fluorescent microscopy studies performed using three different staining methods in combination with Annexin V-FITC flow cytometric analysis clearly demonstrate the ability of EPS to induce cancer cell death via the apoptosis pathway. Moreover, an altered pattern and intensity of the immunocytochemical staining for the apoptosis- and proliferation-related proteins p53, bcl2, and Ki67 was detected in EPS-treated HeLa cancer cells as compared to the untreated controls. The obtained results characterize the new local strain of green microalgae Coelastrella sp. BGV as a producer of EPS with selective antitumor activity and provide an opportunity for further studies of its pharmacological and biotechnological potential.

A dual-responsive fluorescent probe for cellular hypoxia and tumor imaging based on nitroreductase and viscosity synergy

Nitroreductase (NTR), an enzyme that operates within the cytoplasm, relies on flavin mononucleotide or flavin adenine dinucleotide for its activity. In tumor cells, hypoxic conditions often lead to an increase in NTR levels. Consequently, the development of fluorescent probes capable of detecting NTR activity is crucial for the monitoring of hypoxia in biological systems. This study presents the one-step synthesis of a near-infrared fluorescent probe, DSM-NO2. The probe was highly sensitive to NTR and caused a fluorescence enhancement by 50-fold, with a detection limit as low as 1 ng/mL. Under hypoxic conditions in tumor cells, not only does NTR increase, but the cellular viscosity also rises. In high-viscosity environments, the fluorescence enhancement could reach up to 220-fold, and the detection limit could be further reduced to 55 pg/mL. The reaction mechanism was thoroughly investigated using mass spectrometry, molecular docking, and theoretical calculations. Moreover, the probe was successfully applied in the real-time monitoring and visualization analysis of NTR during the growth of Escherichia coli and in the hypoxic state of cancer cells. Additionally, through nebulized inhalation, the probe was successfully employed for in situ fluorescent imaging studies in a murine model of lung cancer.

A novel thermophilic lysozyme 4356 from Cohnella sp. A01: Cloning, heterologous expression, biochemical and kinetic characterization

Lysozymes have gained attention for their antiseptic properties. In silico studies have shown that the enzyme containing lysM can act as an antibacterial agent. Binding of the lysM motif of rSELys to peptidoglycan and molecular dynamics simulations showed that the protein-ligand binding is very stable. rSELys (2016 bp) is a new recombinant glycoside hydrolase from the thermophilic bacterium Cohnella sp. A01 (PTCC number: 1921). Protein expression and purification, a single band with an apparent molecular weight of ∼74 kDa was observed by SDS-PAGE. The kinetic parameters were Km 1.163 mg/ml, Vmax 670.3 U/mg, kcat 1675.75 (S−1), and kcat/Km 1440.88 (M−1S−1). Its optimum temperature was 55 °C and pH 8. Temperature stability also showed that the temperature of 50–60 °C retained more than half of its activity after 90 min. Based on the results, rSELys demonstrated antibacterial effects on both Gram-positive and Gram-negative strains, with inhibition zones of 11 and 9 mm, respectively. SEM analysis confirmed hydrolysis activity, the MIC was determined to be 31.25 μg/ml and 3.9 μg/ml, and MBC 0.97 μg/ml, respectively. CD and fluorescence studies showed that up to a temperature of 85 °C and a pH value of 8–12 no structural changes occur, and thermal stability protein was confirmed.

Elucidating the Binding Interaction of a Highly Efficient Phytochemical-Sinapic Acid with Human Serum Albumin: A Spectroscopic and Calorimetric Approach

Polyphenolic compounds have received much attention due to their major function as antioxidants. Sinapic acid (SA) is an orally bioavailable phytochemical with excellent free radical scavenging property transported in the blood by human serum albumin (HSA) which is the chief carrier protein found abundantly in human plasma. SA contains a single phenolic group. This study investigates the binding and interaction mechanism between SA and HSA by multiple spectroscopic and calorimetric techniques, such as UV/visible absorption spectroscopy, intrinsic fluorescence studies, Fourier transform infrared (FTIR) spectroscopy and isothermal titration calorimetry (ITC). UV/visible absorption spectroscopy showed hyperchromicity in the absorption spectra, suggestive of structural change due to complex formation between HSA and SA. Intrinsic fluorescence measurements, performed at three different temperatures, showed quenching of the fluorescence spectra and the mechanism of quenching was static in nature which occurred due to ground state complex formation. The FTIR results demonstrated a 16% decrease in α-helical content of the secondary structure of HSA in the presence of SA. Hydrogen bonds and hydrophobic forces were the main forces of interaction, according to the thermodynamic characteristics found through ITC. Moreover, the data obtained through ITC indicated strong binding affinity between HSA and SA and supported the exothermic and spontaneous nature of the interaction.

Structural, spectroscopic, fluorescent, and computational studies of binuclear copper (II) and zinc (II) complexes with an asymmetric salamo‐type ligand

Salamo‐type ligand H2L was designed and synthesized and reacted with Cu (II) and Zn (II) acetate, respectively, to obtain two binuclear Cu (II) and Zn (II) complexes: [Cu2(L)2]·2CH3OH (1) and [Zn2(L)2] (2) having the same coordination number but distinct geometries. Complex 1 is a Cu (II) complex containing two crystalline ethanol molecules, where two Cu (II) atoms are surrounded by two utterly deprotonated (L)2− parts, forming slightly twisted tetragonal pyramidal configurations of pentacoordinate. In complex 2, two utterly deprotonated (L)2− parts surround two Zn (II) atoms, forming pentadentate twisted triangular bipyramidal configurations. The complexes were elucidated via IR analyses and ultraviolet spectroscopy. Using DFT theoretical calculation, MEPs, IRI, and Hirshfeld surface analysis to investigate further the molecular interactions and reaction sites. Ultimately, the fluorescence characteristics of H2L and its complexes 1 and 2 were discussed.

Synthesis, Characterization, Investigation of DNA Interactions and Biological Evaluation of Co(II), Ni(II), Cu(II) and Zn(II) Complexes with Newly Synthesized 2-methoxy 5-trifluoromethyl benzenamine Schiff Base.

The biologically active and thermally stable bivalent Co(II), Ni(II), Cu(II), and Zn(II) complexes (C1, C2, C3, and C4) of novel Schiff base ligand [(5-trifluoromethyl-2-methoxyphenylamino)methyl)-4,6-diiodophenol (L)] have been synthesized. The structural analysis of these complexes have been carried out by elemental analysis, 1H-NMR, FTIR, ESI mass, UV-visible, ESR, TGA techniques and magnetic measurements. The obtained results were confirmed as square planar geometry for Ni(II) and Cu(II) complexes, whereas octahedral geometry for Co(II) and Zn(II) complexes. The geometry optimized structures were developed by employing CHEM 3D software. The DNA binding interaction studies such as UV-vis absorption, viscosity, and fluorescence studies have been confirmed that the mode of binding of complexes with DNA is an intercalative binding. The DNA cleavage studies revealed that all the complexes are found to be potent to cleave the DNA into Form I & II. The in-vitro pathological studies of all the complexes against various microbial strains (Gram + and Gram -), revealed that Cu(II) complexes are more potent compared to other complexes and Schiff base. The anti diabetic activity studies revealed that the Cu(II) complex exhibited slightly higher activity than Co(II), Ni(II), and Zn(II) complexes. The results of antioxidant activity by DPPH method, suggested that the Cu(II) complex has higher activity and comparable with the standard compounds.