Volmer Constant Research Articles

A Fluorescence Sensor Based on Biphenolic Backbone for Metal Ion Detection: Synthesis and Crystal Structure

2′-(hexyloxy)-[1,1′-biphenyl]-2-yl 5-(dimethylamino)naphthalene-1-sulfonate (KC1) was synthesized by using biphenol and dansyl chloride as starting materials. The KC1 was characterized via single X-ray diffraction, FTIR, HRMS and 1H and 13C-NMR. The KC1 indicates triclinic as P1 in the space group type. From the KC1, the biphenolic backbone structure is twisted at an angle of 54.48° due to connecting the dansyl unit and hexyl moiety. Upon the addition of the Fe3+ ion to the KC1 solution, the fluorescence emission at 585 nm of KC1 was quenched due to complexation between KC1 and the Fe3+ ion. The complexation ratio of KC1 and Fe3+ was determined to be a 1:1 formation via Job’s analysis. The Stern–Volmer constant (Ksv) calculated was 21,203 M−1 for the KC1 and the Fe3+ ion complex.

Carbohydrate-Binding Mechanism of the Coagulant Lectin from Moringa oleifera Seeds (cMoL) Is Related to the Dimeric Protein Structure

This study characterized the binding mechanisms of the lectin cMoL (from Moringa oleifera seeds) to carbohydrates using spectroscopy and molecular dynamics (MD). The interaction with carbohydrates was studied by evaluating lectin fluorescence emission after titration with glucose or galactose (2.0–11 mM). The Stern–Volmer constant (Ksv), binding constant (Ka), Gibbs free energy (∆G), and Hill coefficient were calculated. After the urea-induced denaturation of cMoL, evaluations were performed using fluorescence spectroscopy, circular dichroism (CD), and hemagglutinating activity (HA) evaluations. The MD simulations were performed using the Amber 20 package. The decrease in Ksv revealed that cMoL interacts with carbohydrates via a static mechanism. The cMoL bound carbohydrates spontaneously (ΔG < 0) and presented a Ka on the order of 102, with high selectivity for glucose. Protein–ligand complexes were stabilized by hydrogen bonds and hydrophobic interactions. The Hill parameter (h~2) indicated that the binding occurs through the cMoL dimer. The loss of HA at urea concentrations at which the fluorescence and CD spectra indicated protein monomerization confirmed these results. The MD simulations revealed that glucose bound to the large cavity formed between the monomers. In conclusion, the biotechnological application of cMoL lectin requires specific methods or media to improve its dimeric protein structure.

Unraveling the Potential of Mononuclear Zn(II) and Cu(II) Schiff Base Metal Complexes: Microwave‐Aided Synthesis, Theoretical Analysis and Application in Biomimetic Catalysis, CT‐DNA Interaction, and In Vitro Biological Assays

ABSTRACTGiven the widespread and diverse effects of transition metal ions such as copper and zinc in multiple biological processes, this research endeavor addresses herein the microwave‐aided synthesis of two novel tetradentate ONNO (L1) and tridentate NNO (L2) donor Schiff base ligands derived from 4,5‐dimethyl‐1,2‐phenylenediamine and 4‐bromo‐2‐hydroxybenzaldehyde in a 1:2 ratio and from 4,5‐dimethyl‐1,2‐phenylenediamine and 5‐methoxy‐2‐hydroxybenzaldehyde in a 1:1 ratio, with their respective zinc, ZnL1(1) and ZnL2(3), and copper, CuL1(2) and CuL2(4), Schiff base metal complexes, which are comprehensively characterized utilizing physiochemical and analytical techniques, along with geometry optimization using the DFT approach. Spectrophotometric analyses have been used to assess the biomimetic activity in the conversion of 3,5‐DTBC to 3,5‐DTBQ with turnover numbers 53.4 and 78 h−1 in methanol for 2 and 4, whereas the zinc complexes are found to be ineffective. With CT‐DNA, possible modes of interaction with the synthesized complexes have been explored using absorption spectroscopy, where the associated binding constants ranged between 1.541 × 105 and 2.186 × 105 M−1. EtBr‐bound DNA was used in the fluorescence quenching experiments with Stern–Volmer constant (Ksv) values in the range 4.084 × 104 and 3.402 × 104 M−1, showing a stronger association with CT‐DNA. The compounds' ability to inhibit bacterial strains was also examined in vitro, as well as their ability to reduce inflammation, through the protein denaturation method and the DPPH assay for antioxidant activity have been performed. Furthermore, molecular docking simulations have been carried out to obtain a deeper comprehension of the molecular‐level interactions with CT‐DNA and cyclooxygenase‐2 (COX‐2).

Synthesis of bridged dinaphthoviologen derivatives for enhanced electrochromic performance and picric acid detection

Electrochromic materials represent a class of highly promising smart materials in contemporary research. Viologen, as a prevalent organic small molecule in smart chromic materials, has garnered extensive attention due to its tunable intermediate structure involving pyridine units and diverse nitrogen atom substituents. In this investigation, the molecular structure of dinaphthoviologen (DNV2+) were modified, and various groups were introduced to ionize nitrogen atoms. This structural modification aimed to decrease the molecular energy gap and enhance the electron acceptability of nitrogen atoms. The results demonstrate robust redox ability in DNV2+. To explore the practical applications, a straightforward DNV2+-based electrochromic device was fabricated, incorporating ferrocene as an electronic supplement. This device exhibited commendable cycling performance (exceeding 1000 cycles) and rapid response times (8 s for coloring and 10 s for fading) without the need for additional electrolytes. Additionally, the transmittance changes by more than 45 %. Moreover, owing to the presence of conjugated structures, DNV2+ exhibited noteworthy fluorescence properties. In fluorescence-based picric acid detection experiments, the synthesized molecules exhibited high selectivity and sensitivity, as evidenced by the determined Stern–Volmer constants (K6b = 2.17 × 104 L/mol, K6c = 3.87 × 104 L/mol). The findings highlight the potential of the developed dinaphthoviologen derivatives for advanced applications in electrochromic devices and sensitive detection of picric acid.

Studying the optoelectronic properties and emission quenching dynamics of poly‐TPD by incorporating ZnO nanoparticles and multiwalled carbon nanotubes

AbstractIn this study, the optoelectronic properties and emission dynamic quenching of poly‐TPD were investigated upon incorporating ZnO nanoparticles and multiwalled carbon nanotubes (MWCNTs). A solution blending method was utilized to successfully prepare poly‐TPD incorporated with various contents of ZnO/MWCNT nanocomposites. The optoelectronic properties of the nanocomposites were analyzed using UV–Vis and photoluminescence spectrophotometry. The incorporation of the nanocomposites resulted in a decrease in transmittance, reflectance, and absorption edge, indicating a reduction in the poly‐TPD's bandgap. Parameters such as extinction coefficient, Urbach energy, and charge carrier density also decreased with addition of the nanocomposites, suggesting increased scattering, disorder, and the presence of defect states. The decrease in bandgap from 2.970 to 2.852 eV with increasing the nanocomposite content confirmed the emergence of new electronic states. Furthermore, the nature of the transitions changed from direct allowed for pure poly‐TPD to direct forbidden upon incorporation of the nanocomposites. The inclusion of the nanocomposites also led to a decrease in refractive index and fluorescence intensity. The observed fluorescence quenching primarily exhibited dynamic characteristics, with a Stern–Volmer constant of 5.14 L/g and quenching rate constants surpassing the minimum threshold for efficient quenching. The increase in charge transfer rate constants with the nanocomposite content indicated enhanced quenching efficiency and charge transfer, likely due to the increased surface area and presence of defects. These findings suggest that poly‐TPD incorporated with ZnO/MWCNT nanocomposites displays promising properties for applications in optoelectronic devices.

Effects of the change of isomers on room-temperature phosphorescence, thermally activated delayed fluorescence, and long persistent luminescence of organic hole-transporting materials with the selective potential for the application in electronic devices and optical sensors of oxygen

Competition of room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) was investigated on the example of four newly synthesised organic isomeric compounds containing two electron-donating triphenylamine moieties and single electron-accepting dibenzothiophene-2-yl(phenyl)methanone unit by numerous theoretical and experimental approaches. The different emission origin (RTP or TADF) of the isomeric compounds was caused by the different energy gaps between the lowest singlet and triplet states locally exited and charge transfer in nature. Very different external quantum efficiencies ranging from 2.8 to 13.9% were observed for green phosphorescent organic light-emitting diodes fabricated using the isomeric compounds as the hosts. Such device efficiency differences were related to the different hole mobility values. The hole mobilities of ca. 1 × 10−3 cm2V−1s−1 were observed at an electric field of 6.4 × 105 V/cm for the derivatives having triphenylamine moieties at C-2, C-4, and at C-3, C-5 positions of the central benzene ring. Considerably lower hole mobilities of ca. 1 × 10−5 cm2 V−1 s−1 were recorded at the same electric field for the compounds with triphenylamine groups at C-2, C-3, and at C-2, C-6 positions. Depending to the great extent on RTP and TADF processes, different efficiencies of long persistent luminescence (LPL) of the exciplex-forming solid-state mixtures of the isomers and bis[2-(diphenylphosphine)phenyl] ether oxide (DPEPO) were detected. The compound with triphenylamine groups at C-3, and C-5 positions as RTP emitter and its molecular mixture with DPEPO as LPL emitter the active layers of optical sensors of oxygen were prepared. They showed the Stern–Volmer constant of 4.55 × 10−4 ppm in the range of oxygen concentrations up to 10000 ppm.

Molecular docking and spectroscopic study of bovine serum albumin interaction with new anticancer Pt complex with isopentyl dithiocarbamate ligand

Although cisplatin is useful in the treatment of cancer, it has a series of side effects that limit its use. Dithiocarbamates reduce the toxicity of platinum due to their structure and the presence of S, and N donating groups. In this article, the interaction of [Pt(bpy)(isopentyl.dtc)]NO3, where bpy is bipyridine and isopentyl.dtc is isopentyl-dithiocarbamate, with BSA, bovine serum albumin has been studied. The molecular binding method, including UV-Vis and fluorescence titration, was carried out in conditions including pH = 7.4 and temperatures of 27 and 37 °C. The negative values of enthalpy (ΔH°b) and entropy (ΔS°b) show that the driving forces of this interaction are hydrogen and van der Waals, and the negative value of the Gibbs free energy, ΔG°b indicates that the interaction proceeds spontaneously. The fluorescence results showed that the quenching mechanism is the static type and the Stern Volmer constant, KSV, was also obtained. The fluorescence titration method data displayed that the quenching mechanism is static. Binding constant (Kb), binding point (n), Hill coefficients, nH, Hill constant, KH, number of binding sites, g, BSA melting temperature, Tm, were also obtained. Finally, the molecular docking method result shows the binding constant, Ki and binding free energy for the platinum complex are −6.53 and 16.39 kcal mol−1, respectively, and also the proper position of binding on BSA can be considered the site I in the subdomain IIA.

Triphenylamine–Anthracene-Based Conjugated Microporous Polymers for the Detection and Photocatalytic Degradation of Organic Micropollutants

Triphenylamine (TPA)–anthracene (AN)-based conjugated microporous polymers (CMPs), namely PTPA-AN-9,10 and PTPA-AN-2,6, were synthesized by the Suzuki–Miyaura cross-coupling reaction of tris(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-amine with 9,10-dibromoanthracene and 2,6-dibromoanthracene, respectively. The as-synthesized polymers exhibited cauliflower-like nanoscale morphology , high Brunauer–Emmett–Teller surface area of 362 m2/g, and thermal stability up to 458 °C in the case of PTPA-AN-2,6. Interestingly, PTPA-AN-9,10 showed bright cyan fluorescence in tetrahydrofuran dispersion and exhibited fluorescence-based sensing of various nitroaromatics, where 2,4,6-trinitrophenol exhibited the lowest limit of detection of 34 μM and the highest Stern–Volmer constant (KSV) of 5.8 × 103 L mol–1. On the other hand, PTPA-AN-2,6 showed efficient photocatalytic reduction of various nitroaromatic micropollutants such as p-nitrophenol (p-NP) (k = 0.164 min–1 and turnover frequency (TOF) = 0.769 h–1) and degradation of Congo red from water with ultrafast kinetics (k = 0.047 min–1 and TOF = 0.024 h–1) which are much better than most of the previously reported CMPs. These polymers were recovered using simple filtration and were recycled four to five times without losing their catalytic efficiency significantly for p-NP reduction as well as dye degradation. In general, TPA-based CMPs have been used as efficient multitasking materials for the sensing of nitroaromatic micropollutants and photocatalytic degradation of Congo red dye as well as p-NP to its value-added product p-aminophenol.

Imidazole-Based Metal–Organic Framework for the “On1–Off–On2” Fluorescence-Based Detection of Picric Acid and the Adsorption of Congo Red

An imidazole-functionalized metal–organic framework (MOF), {[Ba2L (H3CCOO) (DMF)2] (DMF)}n, denoted as HBU-168, has been synthesized and characterized by single-crystal X-ray diffractometry. The synthesized MOF exhibits ligand-based luminescence, which can be attributed to coordination effects. Due to its excellent fluorescence performance, HBU-168 can be used to detect nitroaromatic compounds (NACs) and metal ions selectively and sensitively. The most striking properties of HBU-168 are the distinct red shift (∼34.8 nm) observed in the presence of picric acid (PA) with a Stern–Volmer constant (KSV) of 4.17 × 104. The mechanism of the change in luminescence in the presence of PA is determined by experiments and density functional theory calculations. The results indicate that the electron transfer between PA and the MOF has a reduction in the frontier orbital energy gap. Subsequently, HBU-168 is used to prepare a light-emitting-diode-based sensor (denoted HBU-168-LED), which can detect PA rapidly and visually. In addition, we find that HBU-168 can be used to detect metal ions, particularly magnesium ions. The metal detection mechanism is based on the turn-on fluorescence of HBU-168 caused by weak interactions between the MOF and metal ions. Finally, HBU-168 is found to be a good adsorbent for Congo red, achieving a removal efficiency of 98.89%. Therefore, the multifunctional HBU-168 MOF is a promising luminescent sensor and adsorbent.

Aggregation-Induced Emission-Active Iridium(III) Complexes for Sensing Picric Acid in Water

Herein, two new iridium(III) complexes, namely Ir2 and Ir3, with a phenyl or triphenylamine (TPA) moiety at the 4-position of the phenyl ring at 2-phenylbenzothiazole, have been synthesized, and their emission properties have been studied systematically compared with the non-substituted complex Ir1. These three complexes exhibit aggregation-induced emission (AIE) in H2O/CH3CN. The TPA-substituted complex Ir3 shows the highest AIE activity. All complexes can be used as sensors to detect picric acid (PA) in water. The Stern–Volmer constant (KSV) of Ir3 for the detection of PA was determined to be 1.96 × 106 M−1, with a low limit of detection of 2.52 nM. Proton nuclear magnetic resonance spectra, high-resolution mass spectrometry analysis, and density function theory calculations confirm that the emission quenching mechanism of Ir3 is caused by photo-induced electron transfer. Furthermore, the efficient detection of PA in natural water proves that Ir1–Ir3 can be used as promising sensors in the natural environment. These results suggest that the AIE-active iridium(III) complexes can be used to detect PA under environment-friendly conditions.

Optical Sensing Capability Evaluation for Methylammonium Based Perovskites for Explosive.

Here, we have synthesized methylammonium based two metal halide perovskites (MHP) such as MAPbBr3, and MAPbI3 using methylammonium bromide, methylammonium iodide, lead bromide, respective at room temperature under certain experimental conditions. All synthesized MHPs have been confirmed through X-ray diffraction technique (XRD), scanning electron microscope (SEM), Fourier transform infra-red (FTIR) and photoluminescence (PL) analysis. Afterward, comparative evaluation on optical sensing capability has been made for both MHPs using PL in different solvents. Importantly, we find out that MAPbBr3 exhibit an excellent optical feature over MAPbI3 in hexane only. Afterward, MAPbBr3 has also been explored to know the sensing capability for nitrobenzene sensing. Our model study confirms that MAPbBr3 is an excellent sensing material with R square (0.87), selectivity (16.9%) and Stern Volmer constant (Ksv=10- 2 × 0.464) for nitrobenzene in hexane.

NIR Luminescent Oxygen-Sensing Nanoparticles for Continuous Glucose and Lactate Monitoring.

A highly sensitive, biocompatible, and scalable phosphorescent oxygen sensor formulation is designed and evaluated for use in continuous metabolite sensors for biological systems. Ethyl cellulose (EC) and polystyrene (PS) nanoparticles (NPs) stabilized with Pluronic F68 (PF 68), Polydimethylsiloxane-b-polyethyleneglycol methyl ether (PDMS-PEG), sodium dodecylsulfate (SDS), and cetyltimethylammonium bromide (CTAB) were prepared and studied. The resulting NPs with eight different surfactant−polymer matrix combinations were evaluated for physical properties, oxygen sensitivity, effect of changes in dispersion matrix, and cytotoxicity. The EC NPs exhibited a narrower size distribution and 40% higher sensitivity than PS, with Stern−Volmer constants (Ksv) 0.041−0.052 µM−1 for EC, compared to 0.029−0.034 µM−1 for PS. Notably, ethyl cellulose NPs protected with PF68 were selected as the preferred formulation, as they were not cytotoxic towards 3T3 fibroblasts and exhibited a wide phosphorescence lifetime response of >211.1 µs over 258−0 µM and ~100 µs over 2.58−0 µM oxygen, with a limit of detection (LoD) of oxygen in aqueous phase of 0.0016 µM. The EC-PF68 NPs were then efficiently encapsulated in alginate microparticles along with glucose oxidase (GOx) and catalase (CAT) to form phosphorescent nanoparticles-in-microparticle (NIMs) glucose sensing microdomains. The fabricated glucose sensors showed a sensitivity of 0.40 µs dL mg−1 with a dynamic phosphorescence lifetime range of 46.6−197.1 µs over 0−150 mg dL−1 glucose, with a glucose LoD of 18.3 mg dL−1 and maximum distinguishable concentration of 111.1 mg dL−1. Similarly, lactate sensors were prepared with NIMs microdomains containing lactate oxidase (LOx) and found to have a detection range of 0−14 mg dL−1 with LoD of 1.8 mg dL−1 and maximum concentration of 13.7 mg dL−1 with lactate sensitivity of 10.7 µs dL mg−1. Owing to its versatility, the proposed NIMs-based design can be extended to a wide range of metabolites and different oxygen-sensing dyes with different excitation wavelengths based on specific application.

Metal–Organic-Framework-Based Chemosensor for Ultrafast and Ultrasensitive Detection of Pd2+ Ions in Water, Real Specimens, and Test Strips

A new ultrasensitive and ultrafast Al(III) metal-organic-framework (MOF)-based probe (1) was constructed to detect Pd2+ ions. Extremely selective recognition of Pd2+ ion was demonstrated by the guest-free compound 1 (called 1') using a fluorescence signal. The quenching in the fluorescence signal was observed due to the weak interaction between the linker alkyne-π bond and Pd2+. The mechanism of isophthalic alkyne-π and Pd2+ interaction was systematically examined with the help of isothermal titration calorimetry (ITC), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy. The response time of the MOF for sensing of Pd2+ was 30 s, which is the lowest response time for MOF-based Pd2+ sensing to date, with an ultralow detection limit (102 nM) and Stern-Volmer constant (4.39 × 103 M-1), evidencing the outstanding ability to sense Pd2+ ion by this probe. The Pd2+ detection limit falls among the lowest values. Activated MOF (1') also showed considerable recyclability up to five steps with a constant sensing ability. In different water resources (Milli-Q water, lake water, river water, and tap water), the probe also showed excellent sensing ability. A paper-strip device was developed for the applicability of our material for the real field sensing application of Pd2+. The relevance of 1' is not only up to Pd2+, but it could also sense palladium in other possible oxidation states.

Luminescent Porphyrinic Metal–Organic Frameworks for Oxygen Sensing: Correlation of Nanostructure and Sensitivity

Oxygen sensing capabilities of a series of luminescent zirconium-based porphyrinic metal–organic frameworks (MOFs) (PCN-222, PCN-223, and PCN-224) have been investigated. Design of experiments allowed identification of the most sensitive material, a PCN-224 MOF. In this material, luminescence in air is quenched by up to 7.3-fold with a bimolecular quenching constant kq of 56,000 Pa–1 s–1, which is significantly above the previously reported benchmark material of the same MOF type (kq of 34,000 Pa–1 s–1). The oxygen sensitivity increases in the order PCN-222 < PCN-223 < PCN-224 with effective Stern–Volmer (SV) constants in the range of 0.13 kPa–1 for PCN-222, 0.18 kPa–1 for PCN-223 and up to 0.45 kPa–1 for PCN-224-type materials. This effect is attributed to the increase in the porphyrin–porphyrin separation in these nanostructured materials that results in the increase in the fluorescence decay time and thus the probability of the quenching event. Defects in the nanostructure also are important and explain variations in the sensitivity within the MOFs of the same type. Among the investigated materials, those belonging to the PCN-223 type were found to be the most robust in terms of oxygen sensing capabilities with only little variation in the SV constants. The analogues of the PCN MOFs that utilize a Pt(II) porphyrin as a building block were also prepared. It is shown that the same synthetic protocols established for the metal-free systems can be used for the metal complex. Analogous to the MOFs based on the metal-free porphyrin, the oxygen sensitivity increases from Pt(II)PCN-222 (KSV 30 kPa–1) via Pt(II)PCN-223 (KSV 40 kPa–1) to Pt(II)PCN-224 (KSV up to 87 kPa–1).

Rational design of bromine-modified Ir(III) photosensitizer for photocatalytic hydrogen generation

The facile design of highly efficient photosensitizers is fundamentally crucial for the construction of efficient photocatalytic H2-evolving systems. In this work, we employed substituted 2-(thiophen-2-yl) pyridine (C^N) and 2,2′-bipyridine (N^N) ligands to afford a series of iridium complexes. Interestingly, by introducing heavy halogen group -Br, the triplet state lifetime of affording photosensitizer was significantly enhanced to 4273 ns, which is 54 times to that of unmodified one (77 ns). While coupling with Ni-substituted polyoxometalate Ni4(SiW9)2 catalyst and triethanolamine electron donor, the bromine-modified photosensitizer can effectively drive hydrogen generation with a turnover number of ∼ 1400 under visible light irradiation. Spectroscopic studies reveal that the -Br modified iridium complex exhibits larger Stern − Volmer constants for both reductive and oxidative quenching processes. Mechanistic analyses demonstrate the advantages of long-lived excited states and good photostability of bromine modified photosensitizer, the efficient electron transfer process, and the well-matched energy levels between all three catalytic components for efficient hydrogen production.

Selective Sensing of Darolutamide and Thalidomide in Pharmaceutical Preparations and in Spiked Biofluids.

Selective spectrofluorometric sensing is introduced for the analysis of non-steroidal anti-androgens, darolutamide, and thalidomide in pharmaceutical preparations and biofluids. An organic fluorophore, 2,4,8,10-tetramethylpyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidine 2 was synthesized in our laboratories by new simple methods to act as a fluorescent reagent for the analysis of the studied drugs. Elemental and spectral analyses were performed to approve the fluorophore structure. The fluorophore possesses a fluorescence at λem 422 nm when excited at 328 nm. The interaction between the studied drugs and the fluorophore was found to be quenching. The quenching mechanisms were studied and interpreted through the Stern-Volmer relationship. Moreover, the Stern-Volmer constants were calculated for the quenching interactions of both drugs. The introduced method was validated for the estimation of darolutamide and thalidomide in dosage forms, plasma, and urine, offering good percentage recoveries.

The Influence of Cationic Nitrosyl Iron Complex with Penicillamine Ligands on Model Membranes, Membrane-Bound Enzymes and Lipid Peroxidation.

This paper shows the biological effects of cationic binuclear tetranitrosyl iron complex with penicillamine ligands (TNIC-PA). Interaction with a model membrane was assessed using a fluorescent probes technique. Antioxidant activity was studied using a thiobarbituric acid reactive species assay (TBARS) and a chemiluminescence assay. The catalytic activity of monoamine oxidase (MAO) was determined by measuring liberation of ammonia. Antiglycation activity was determined fluometrically by thermal glycation of albumine by D-glucose. The higher values of Stern-Volmer constants (KSV) obtained for the pyrene located in hydrophobic regions (3.9 × 104 M-1) compared to KSV obtained for eosin Y located in the polar headgroup region (0.9 × 104 M-1) confirms that TNIC-PA molecules prefer to be located in the hydrophobic acyl chain region, close to the glycerol group of lipid molecules. TNIC-PA effectively inhibited the process of spontaneous lipid peroxidation, due to additive contributions from releasing NO and penicillamine ligand (IC50 = 21.4 µM) and quenched luminol chemiluminescence (IC50 = 3.6 μM). High activity of TNIC-PA in both tests allows us to assume a significant role of its radical-scavenging activity in the realization of antioxidant activity. It was shown that TNIC-PA (50-1000 μM) selectively inhibits the membrane-bound enzyme MAO-A, a major source of ROS in the heart. In addition, TNIC-PA is an effective inhibitor of non-enzymatic protein glycation. Thus, the evaluated biological effects of TNIC-PA open up the possibility of its practical application in chemotherapy for socially significant diseases, especially cardiovascular diseases.

Fluorescence quenching, DFT, NBO, and TD-DFT calculations on 1, 4-bis [2-benzothiazolyl vinyl] benzene (BVB) and meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS) in the presence of silver nanoparticles

Steady-state fluorescence measurements were used to examine the fluorescence quenching of 1, 4-bis [-(2-benzothiazolyl) vinyl benzene (BVB) by sodium salt of meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS) in the presence and absence of silver nanoparticles (Ag NPs). The energy transfer (ET) process’s emission intensities and Stern–Volmer constants (KSV) showed that Ag NP’s presence increased ET’s efficiency. The molecular structures of TPPS, TPPS, and BVB/TPPS were optimized using the DFT/B3LYP/6-311G (d) technique to elucidate the mechanism. The discovered optimized molecular structure proved that whereas TPPS and BVB/TPPS MSs are not planar because the porphyrin group in TPPS is rotated out by phenyl sodium sulphate, the BVB MS is planer. All of the theoretical BVB results and the acquired experimental optical results were very similar.

A new heterotrimetallic sandwich‐like CuII–LaIII–CuII (3d–4f–3d) cluster as a model anticancer drug in interaction with FS‐DNA and BSA and as a new artificial catalyst for catecholase activity

A new heterotrimetallic sandwich‐like CuII–LaIII–CuII cluster, [(valpn)2Cu2La(NO3)2]NO3(H2O)1.8, (H2valpn = 1,3‐propanediylbis(2‐iminomethylene‐6‐methoxy‐phenol)), was synthesized by the reaction of [Cu(valpn)] with La (NO3)3.6H2O (1:1 M ratio) at room temperature. The resulted cluster was characterized by X‐ray diffraction, UV–Vis and IR spectroscopy, and elemental analysis (CHN). The crystal structure of the cluster revealed that La(III) ion was sandwiched between two [Cu(valpn)] moieties and located in the open compartments of two copper Schiff base complexes and being surrounded by 12 oxygen atoms. This cluster complex, as a model anticancer drug, was investigated in interaction with fish sperm deoxyribonucleic acid (FS‐DNA) using docking study and experimental methods such as fluorescence and UV–Vis spectroscopy, circular dichroism spectroscopy (CD), cyclic voltammetry (CV), viscosity measurements, and agarose gel electrophoresis. These investigations suggested intercalative interaction between the cluster complex and FS‐DNA. Plasma proteins are other targets for the anticancer drugs, so the cluster–bovine serum albumin (BSA) interaction was also investigated. For evaluating the binding, Stern–Volmer constants (KSV) and the number of binding sites (n) were calculated. It was proposed that the electrostatic interaction was the main force in the cluster–BSA binding. Cytotoxic activity was assayed by MTT assay toward LACaP, MCF‐7, and HeLa cancer cell lines. The IC50 values of the cluster for HeLa and LACaP cell lines were lower than for MCF‐7 cell lines. The docking studies were also performed for cluster–BSA and cluster–DNA interactions. The cluster was also investigated as an artificial enzyme in catechol oxidase activity, and kinetics of the oxidation of 3,5‐di‐tert‐butylcatechol catalyzed by the cluster was studied.

Azine- and azo-based flexible covalent organic frameworks for fluorescence sensing nitro-aromatic compounds and iodine and adsorbing iodine

By Schiff base polycondensation reactions, hydrazine hydrate (HAZ) or 4,4′-Azodianiline (AZDA) with hexa(4-formyl-phenoxy)cyclotriphosphazene (NOP-6-CHO) under solvothermal conditions yield flexible crystalline covalent organic frameworks (HHAZ and HAZDA). The azine- and azo-based frameworks showcase permanent porosity, outstanding thermal and chemical stability. HHAZ and HAZDA are highly fluorescent dispersed in polar solvents and emit green and light blue fluorescence under UV light of 365 nm, respectively. HHAZ and HAZDA can detect 2,4-dinitrotoluene (DNT), trinitrophenol (TNP) and iodine with extremely high sensitivity and selectivity. The Stern–Volmer constants of HHAZ for DNT and HAZDA for TNP are 9.40 × 104 and 1.59 × 105 L mol−1. The Stern–Volmer constants of HHAZ and HAZDA for iodine are 2.76 × 104 and 1.56 × 104 L mol−1. Limits of detection are from 1.89 × 10−12 to 1.09 × 10−10 mol L−1. Moreover, pretty and reversible adsorption properties to volatile iodine which can up to 2.27 and 5.18 g g−1 are found in the prepared COFs. Polyiodide plays a momentous role in iodine adsorption, as we detected high contents of polyiodide (I3−and I5−) in adsorbents.