Vanadyl Complexes Research Articles

Optimized Substrate Positioning Enables Switches in the C-H Cleavage Site and Reaction Outcome in the Hydroxylation-Epoxidation Sequence Catalyzed by Hyoscyamine 6β-Hydroxylase.

Hyoscyamine 6β-hydroxylase (H6H) is an iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenase that produces the prolifically administered antinausea drug, scopolamine. After its namesake hydroxylation reaction, H6H then couples the newly installed C6 oxygen to C7 to produce the drug's epoxide functionality. Oxoiron(IV) (ferryl) intermediates initiate both reactions by cleaving C-H bonds, but it remains unclear how the enzyme switches the target site and promotes (C6)O-C7 coupling in preference to C7 hydroxylation in the second step. In one possible epoxidation mechanism, the C6 oxygen would─analogously to mechanisms proposed for the Fe/2OG halogenases and, in our more recent study, N-acetylnorloline synthase (LolO)─coordinate as alkoxide to the C7-H-cleaving ferryl intermediate to enable alkoxyl coupling to the ensuing C7 radical. Here, we provide structural and kinetic evidence that H6H does not employ substrate coordination or repositioning for the epoxidation step but instead exploits the distinct spatial dependencies of competitive C-H cleavage (C6 vs C7) and C-O-coupling (oxygen rebound vs cyclization) steps to promote the two-step sequence. Structural comparisons of ferryl-mimicking vanadyl complexes of wild-type H6H and a variant that preferentially 7-hydroxylates instead of epoxidizing 6β-hydroxyhyoscyamine suggest that a modest (∼10°) shift in the Fe-O-H(C7) approach angle is sufficient to change the outcome. The 7-hydroxylation:epoxidation partition ratios of both proteins increase more than 5-fold in 2H2O, reflecting an epoxidation-specific requirement for cleavage of the alcohol O-H bond, which, unlike in the LolO oxacyclization, is not accomplished by iron coordination in advance of C-H cleavage.

Spectral analysis and characterization of Na2O-SiO2-ZrO2 glasses doped with V2O5

Na2O-SiO2-ZrO2 glasses doped with V2O5 were prepared with the melt quenching method, and were then analyzed using various techniques; in particular, with X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and optical absorption, photoluminescence, electron spin resonance (ESR), and Fourier transform infrared (FT-IR) transmission spectroscopy. The obtained results indicate that, in the studied glasses, vanadyl complexes tend to undergo a reduction from V5+ ions to V4+ ions. XRD and EDS data suggest that the glasses have amorphous nature with randomly distributed grains within the glass matrix. The optical absorption spectra show two transitions: 2B2g→2B1g and 2B2g→2Eg. The photoluminescence spectra exhibit a broad band from 750-900 nm, indicating the 2E→2T2 transition of vanadyl ions. The energies of the band gaps decreased gradually with increasing V2O5 content. The ESR spectra suggest that V4+ ions are situated in octahedral sites with tetragonal compression. The FT-IR spectra confirm the presence of various structural units within the glasses. Finally, the dielectric properties of the glasses were also measured, showing that the dielectric constant (ε′) and the loss tangent (tan δ) increase as the content of vanadium ions increases, indicating presence of V4+ ions within the glass matrix.

Synthesis of Vanadyl Complexes of N-Confused Porphyrins and Their Bromoperoxidase-like Catalytic Activity.

Two new vanadyl complexes of N-confused porphyrins (NCPs), [VONCTPP] (V-1) and [VONCP(OMe)8] (V-2), have been synthesized for the first time and investigated as a catalyst for the oxidative bromination reaction of phenol and its derivatives. This article further delineates crystal structures, photophysical, and redox properties of both the vanadyl complexes. Complexes V-1 and V-2 exhibited a significant red shift in their absorption spectra compared with their respective free bases. The single-crystal structure of V-1 revealed that the complex is in the 2H tautomeric form, while EPR studies revealed the +4 oxidation state of vanadium metal having an axial compression with dxy1 configuration. Catalytic potential for bromoperoxidases-like activity has been explored for both complexes V-1 and V-2 for the first time in NCP chemistry with excellent TOF values (4.7-6.3 s-1 for V-1 and 7.3-8.7 s-1 for V-2) using KBr as a source of bromine and H2O2 as a green oxidant in aqueous acidic medium at 298 K. Notably, both catalysts show excellent recyclability over five cycles. The vanadyl-metalated NCPs exhibit excellent stability in the air.

Approaches to selective and potent inhibition of glioblastoma by vanadyl complexes: Inducing mitotic catastrophe and methuosis

Drug resistance has been a major problem for cancer chemotherapy, especially for glioblastoma multiforme that is aggressive, heterogeneous and recurrent with <3% of a five-year survival and limited methods of clinical treatment. To overcome the problem, great efforts have recently been put in searching for agents inducing death of tumor cells via various non-apoptotic pathways. In the present work, we report for the first time that vanadyl complexes, i.e. bis(acetylacetonato)oxidovanadium (IV) (VO(acac)2), can cause mitotic catastrophe and methuotic death featured by catastrophic macropinocytic vacuole accumulation particularly in glioblastoma cells (GCs). Hence, VO(acac)2 strongly suppressed growth of GCs with both in vitro (IC50 = 4–6 μM) and in vivo models, and is much more potent than the current standard-of-care drug Temozolomide. The selective index is as high as ∼10 or more on GCs over normal neural cells. Importantly, GCs respond well to vanadium treatment regardless whether they are carrying IDH1 wild type gene that causes drug resistance. VO(acac)2 may induce methuosis via the Rac-Mitogen-activated protein kinase kinase 4 (MKK4)-c-Jun N-terminal kinase (JNK) signaling pathway. Furthermore, VO(acac)2-induced methuosis is not through a immunogenicity mechanism, making vanadyl complexes safe for interventional therapy. Overall, our results may encourage development of novel vanadium complexes promising for treatment of neural malignant tumor cells.

Electrochemical studies, adsorption behavior, and spectroscopic analysis of vanadyl complex of bis(1-(pyridin-2-yl)ethylidene)malonohydrazide as efficient eco-friendly corrosion inhibitor for low carbon steel in 1M HCl

Corrosion is a destructive attack that can effect on a substance. One of the most important problems is corrosion losses, which can cause a loss of 10% of the metallic output every year. A novel VO+2 complex of N1, N3-bis(1-(pyridin-2-yl)ethylidene)malonohydrazide [(VO)2(L)(OH)2].H2O has been prepared and utilized as corrosion controller for Low carbon steel (LCS) in hydrochloric acid solution. Chemical (Weight loss (WL)), electrochemical (electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP)) are utilized to examine the effectiveness of prepared [(VO)2(L)(OH)2].H2O (VOL). The inhibition efficacy improved with increasing the VOL doses. The maximum efficacy of the investigated inhibitor is 96.1% at 21×10−6 M. However, at 21×10−6 M, the efficacy decreased from 96.1% to 84.4% when the temperature elevated from 298 to 318 K. The adsorption of VOL on the LCS surface was used to explain the inhibition. According to the values of ∆G°ads, which ranged from 25.8 to 21.5 kJ mol−1, the adsorption of the VOL on the LCS surface is physical adsorption. Analyzing the polarization curves of synthesized inhibitors revealed that they were mixed-type inhibitors. LCS was found to be surface inhibited when coated with a thin film of inhibitors, and surface morphology was assessed by different techniques such as scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) was employed to explain the nature of the interface among VOL and LCS surfaces. It was found that all of these used tests agreed with each other.

Influence of the nature of solvents on the spectroscopic properties of some vanadyl complexes

The article presents a study of the influence of the nature of chemical solvents on the spectroscopic properties of vanadyl complexes. These compounds are used as biologically active analytical reagents and catalysts. Vanadyl (II) complexes were structured according to a typical procedure. To determine the spectral and luminescent properties of the synthesized organic compounds, dimethyl sulfoxide and distilled water were used. The results of the obtained experimental and computational studies show that the compounds under study change their spectral characteristics with the addition of binary solvents.

Quantum spin coherence and electron spin distribution channels in vanadyl-containing lantern complexes.

We herein investigate the heterobimetallic lantern complexes [PtVO(SOCR)4] as charge neutral electronic qubits based on vanadyl complexes (S = 1/2) with nuclear spin-free donor atoms. The derivatives with R = Me (1) and Ph (2) give highly resolved X-band EPR spectra in frozen CH2Cl2/toluene solution, which evidence the usual hyperfine coupling with the 51V nucleus (I = 7/2) and an additional superhyperfine interaction with the I = 1/2 nucleus of the 195Pt isotope (natural abundance ca. 34%). DFT calculations ascribe the spin density delocalization on the Pt2+ ion to a combination of π and δ pathways, with the former representing the predominant channel. Spin relaxation measurements in frozen CD2Cl2/toluene-d8 solution between 90 and 10 K yield Tm values (1-6 μs in 1 and 2-11 μs in 2) which compare favorably with those of known vanadyl-based qubits in similar matrices. Coherent spin manipulations indeed prove possible at 70 K, as shown by the observation of Rabi oscillations in nutation experiments. The results indicate that the heavy Group 10 metal ion is not detrimental to the coherence properties of the vanadyl moiety and that Pt-VO lanterns can be used as robust spin-coherent building blocks in materials science and quantum technologies.

Oxovanadium electronics for in-memory, neuromorphic, and quantum computing applications.

Vanadium is a critical raw material. In the nearby future, it may, however, become one of the key elements of computer devices based on two-dimensional arrays of spin qubits for quantum information processing or charge- and resistance-based data memory cells for non-volatile in-memory and neuromorphic computing. The research and development (R&D) of vanadium-containing electronic materials and methods for their responsible fabrication underpins the transition to innovative hybrid semiconductors for energy- and resource-efficient memory and information processing technologies. The combination of standard and emerging solid-state semiconductors with stimuli-responsive oxo complexes of vanadium(IV,V) is envisioned to result in electronics with a new room-temperature device nanophysics, and the ability to modulate and control it at the sub-nanometer level. The development of exponential (Boolean) logics based on the oxovanadium-comprising circuitry and crossbar arrays of individual memristive cells for in-memory computing, the implementation of basic synaptic functions via dynamic electrical pulses for neuromorphic computing, and the readout and control of spin networks and interfaces for quantum computing are strategically important future areas of molecular chemistry and applied physics of vanadium.

Repurposing Therapeutic Drugs Complexed to Vanadium in Cancer.

Repurposing drugs by uncovering new indications for approved drugs accelerates the process of establishing new treatments and reduces the high costs of drug discovery and development. Metal complexes with clinically approved drugs allow further opportunities in cancer therapy-many vanadium compounds have previously shown antitumor effects, which makes vanadium a suitable metal to complex with therapeutic drugs, potentially improving their efficacy in cancer treatment. In this review, covering the last 25 years of research in the field, we identified non-oncology-approved drugs suitable as ligands to obtain different vanadium complexes. Metformin-decavanadate, vanadium-bisphosphonates, vanadyl(IV) complexes with non-steroidal anti-inflammatory drugs, and cetirizine and imidazole-based oxidovanadium(IV) complexes, each has a parent drug known to have different medicinal properties and therapeutic indications, and all showed potential as novel anticancer treatments. Nevertheless, the precise mechanisms of action for these vanadium compounds against cancer are still not fully understood.

Interfacial Water Molecules as Agents for Phase Change Control and Proton Conductivity Enhancement in the Ammonium Vanadyl Tartrate System.

This study demonstrates the reversible structural transformation, single-crystal-to-single-crystal, of the ammonium vanadyl (L-tartrate) complex salt from the hydrate phase to the anhydrous phase. The transformation can be initiated by stimuli, such as temperature, humidity, or vacuum conditions. The hydrate and anhydrous phases exhibit a tetragonal structure (P41212), with marked differences in hydrogen bonding due to the presence or absence of one water molecule per asymmetric unit. The intricate relationship between crystal packing and intermolecular interactions in the hydrate phase was investigated by crystallographic charge density analysis revealing, at the molecular level, the reasons for the observed 5 orders of magnitude higher proton conductivity of the hydrate phase compared to that of the anhydrous phase. To gain further insight into the processes occurring at the surfaces of grain boundaries and the proton transfer mechanisms in this system, rehydration of the complex salt was carried out by using D2O instead of H2O and monitored by in situ ATR-FTIR spectroscopy. The results highlight the critical role of interfacial water molecules in driving structural transformations and influencing proton conductivity.

Asymmetric Cross Couplings of Trifluoromethyl Radical to Vinylarenes with N‐Hydroxy‐oxazinediones and Subsequent Aerobic Oxidative Homocoupling of 2‐Naphthols Catalysed by Chiral Vanadyl Complexes

AbstractAsymmetric three‐component, 1,2‐aminoxy‐trifluoromethylation of styrenes with N‐hydroxy‐1,3‐benz/naphthoxazine‐2,4‐diones (i. e., N‐OH‐(B/Np)OxzOn) catalysed by chiral vanadyl complexes derived from N‐salicylidene‐L‐t‐leucinate were explored. Among 14 different solvents and 13 different catalysts screened, the best reaction scenarios were in 2‐propanol with 3‐(2,5‐dimethyl)phenyl‐5‐bromo (DMP), or 3‐t‐butyl‐5‐bromo substituted catalysts that led to the corresponding complementary (R)‐ and (S)‐products with potential biological activities in 45–91% yields and up to 85 and 75% ee, respectively. Further optimisation with the DMP catalyst led to the best combination of 3‐halo/3,5‐dihalo‐styrenes with 6‐/7‐Br−N−OH‐(B/Np)OxzOn as the trapping agents. The corresponding eight different products were isolated in 52–75% yields with ees in a range of 88–93% (R). Based on Density Functional Theory (DFT) calculations with conformational searches, the origin of enantiocontrol and the working mechanism were proposed by resorting to a bidentate‐chelation between the amide or carbamate C=O group and N−OH group in the trapping agent to the vanadyl center followed by asymmetric benzylic radical trapping in an SH2 fashion. Subsequent Fragment Molecular Orbital (FMO)/Pair Interaction Energy Decomposition Analysis (PIEDA) calculations with the DMP catalyst were carried out to rationalize the extent of asymmetric induction. One representative product derived from p‐methyl‐styrene and NpOxzOn was hydrolyzed in basic MeOH with decarboxylation to unmask its carbamate moiety. The resulting chiral (R)‐N‐benzoxy‐3‐hydroxy‐2‐naphthamide was subjected to aerobic, oxidative homo‐coupling catalysed by the DMP catalyst in CCl4. The corresponding 2,2‐binaphthol product was isolated in 90% (brsm) yield with nearly complete diastereo‐control at the created (M)‐axial chirality, allowing for sequential, bi‐functional asymmetric cross‐coupling applications.

Novel vanadyl complexes synthesis, characterization and interactions with bovine serum albumin-effects on STZ- diabetes rats.

Drug-protein interactions are essential since most administered drugs bind abundantly and reversibly to serum albumin and are delivered mainly as a complex with protein. The nature and strength of drug-protein interactions have a big impact on how a drug works biologically. The binding parameters are useful in studying the pharmacological response of drugs and the designing of dosage forms. Serum albumin is regarded as optimal model for in vitro research on drug-protein interaction since it is the main protein that binds medicines and other physiological components. In this perspective, binary complex have been synthesized and characterized, from vanadium metal and acetylacetone(4,4,4-trifluoro-1-(2-theonyl)-1,3-butanedione). Imidazole, 2-Methyl-imidazole, and 2-Ethyl-imidazole auxiliary ligands were employed for the synthesis of ternary complexes. Additionally, UV absorption and fluorescence emission spectroscopy were used to examine the binding interactions between vanadium complexes and Bovine Serum Albumin. The outcomes of the binding studies and spectral approaches were in strong agreement with one another. These complexes upon inoculation into diabetes-induced Wistar rats stabilized their serum glucose levels within 3 days. From various studies, it was discovered that the ordering of glucose-lowering actions of these metal complexes were equivalent. The vanadium ternary metal complex derived from (4,4,4-trifluoro-1-(2-theonyl)-1,3-butanedione) and imidazole as ligands is the best among the other metal vanadium complexes.

Change in the Concentration of Stable Free Radicals and Vanadyl Complexes in the Products of Reaction of Petroleum Asphaltenes with Sulfuric Acid

Change in the Concentration of Stable Free Radicals and Vanadyl Complexes in the Products of Reaction of Petroleum Asphaltenes with Sulfuric Acid

Synthesis, spectral elucidation, thermal study, DFT calculations and biological application of new nano sized coordination compounds of a barbiturate based ligand

Novel titanium (IV), vanadyl (II), nickel (II), copper (II), cobalt (II), mercury (II) and silver (I) coordination compounds were established from a ligand created from a diazotization coupling process between 1-(4-aminophenyl)ethanone and barbituric acid. Analytical, spectroscopic, and thermal approaches were used to detect the best structural geometry of the compounds. The coordination compounds were constructed with (1M:2L) stoichiometry. With the exception of titanium (IV), vanadyl (II), and silver (I), all chelated compounds were non-electrolytes. Except for the vanadyl complex, which possessed square pyramidal geometry, and the silver one with tetrahedral geometry, the chelates of titanium (IV), copper (II), nickel (II), mercury (II) and cobalt (II) possessed an octahedral one. The ligand functioned as an ON-neutral bidentate moiety. The thermal manner of all compounds was studied by thermogravimetric analysis (TGA). According to XRD and TEM analysis, all compounds were nanosized. Theoretical calculations were performed to gain more information about the structure of the ligand and Ag chelate by DFT/B3LYP/LanL2DZ. The ligand and some of its chelates were explored as antibacterial, antifungal, and antitumor agents. According to the findings, the (H2L) activity was enhanced by complexation. The antitumor activity of the Ag(I) chelate was dramatically higher than that of the ligand and other chelates, with an IC50 of 11.5 gmL-1. For antimicrobial, Cu(II) chelate outperformed other complexes and the control drug against A. brasiliensis, B. cereus and P. vulgaris.

Development of nanofunctionalized oxovanadium(IV) complex and its anticancer, antidiabetic, DNA cleavage and cell imaging studies

VO(IV) complex is little toxic and highly effective than vanadium salts. A vanadyl metal complex from 8-formyl-7-hydroxy-4-methyl coumarin derivative has been synthesized and functionalized with copper nanoparticles. The Spectrochemical studies such as UV, FTIR, 1NMR and ESR spectra were recorded to characterize the ligand(CUAP), Vanadyl complex[VO(CUAP)SO4] and nano Cu-VO(IV)complex efficiently. The structural studies of vanadyl complex confirmed that the ligand coordinate with metal through nitrogen atom of azomethine, carbonyl oxygen and phenolic oxygen. ESR spectrum of vanadyl complex revealed the covalent nature. XRD pattern of nano Cu-VO(IV) complex indicated the crystalline nature and the average particle size was 20.91 nm. SEM image of nano Cu-VO(IV) complex showed that the nano particles accumulated to form spherical shaped particles. The particle size obtained from Transmission Electron Microscopy of nano functionalized metal complex is ∼ 20 nm. It is closely matched to the particle size calculated from XRD results. Fluorescence of vanadyl complex and nano Cu-VO(IV) complex exhibit the emission from 270 to 900 nm range with significant fluorescence at ∼ 750 nm. The DNA cleavage of all the compounds was evaluated using Agarose gel electrophoresis technique and showed greater cleavage of vanadyl complex. The anticancer activity of compounds was carried out against two cancer cell lines viz Human Breast Cancer Cell line (MCF-7) and Human Leukemia Cancer Cell Line(K-562). Oxovanadium complex exhibited good anticancer activities than ligand and nano-functionalized complex. The antidiabetic activities of vanadyl and nano functionalized complexes were studied against α-Amylase and β-Glucosidase inhibition assay. In this study vanadyl complex showed higher inhibition activity on α-Amylase compared with standard Acarbose. The bioimaging of nano-functionalized metal complex showed high fluorescent properties. The molecular docking study of ligand and vanadyl complex showed greater docking results with CDK2 receptor.

Bioreactivity of divalent bimetallic vanadyl and zinc complexes bis-oxalyldihydrazone ligand against microbial and human cancer series. ctDNA interaction mode

Two novel divalent bimetallic complexes were constructed from the complexation of O=V4+ and Zn2+ ions (VOL and ZnL), respectively, with diisatin oxalyldihydrazone ligand (H2L). Various spectroscopic tools were used to confirm their chemical structures (FT-IR, NMR, EI-Mass, and electronic spectra), besides, elemental analyses and conductivity features. To estimate the role of divalent metal ions in their coordination compound for developing their bio-reactivity, the free ligand H2Lox, and its complexes (VOL and ZnL) were employed spectroscopic investigations against the growth of some microbial series (fungi and bacteria) and also against three human cancer/normal cells. Furthermore, their interaction behavior against calf thymus DNA (ctDNA) was studied through viscometric and spectrophotometric studies to discover the role of O=V4+ and Zn2+ ions to determine the mode of binding with ctDNA. The inhibiting effect of H2L, VOL, and ZnL versus the titled microbial (bacterial and fungal) was built upon their inhibited zone areas in mm and the MIC concentrations in μM. Their action against the three human cancer cells' growth was evaluated by IC50 values in μM and the selectivity index in percentage.Both VOL and ZnL complexes exhibited an amazing series with three human cancer cell growth (according to the zone values in mm of inhibition, MIC in μM, and IC50 values in μM) compared to those of their uncoordinated H2L ligand. VOL demonstrated a distinguished interacting behavior with ctDNA more than that interaction of ZnL depending on the variation of the central metal ion chemical features. Within the covalent and non-covalent interaction modes, the interaction binding between H2L, VOL, and ZnL with ctDNA was discussed based on the electronic spectroscopic observation.

In-vitro antidiabetic activity, theoretical investigation by DFT and molecular docking of mono oxo vanadyl (IV) azomethine macromolecule

Prospective antidiabetic applicant [VO(IV)HBDB] was synthesized qualitatively and rapidly, spending HBDB of the mode N, N′-bis (2-hydroxy benzylidene)-1,2-diaminobenzene/Salophen a well familiar Schiff base with myriad property. Interesting and valuable details of physical and electronic properties, band gap energy, electronic configuration, and NLO possessions of the complex were reported. The complex consent with extraordinary NLO property accords with first-order hyperpolarizability. The impressiveness of the monooxo Vanadyl complex is elevated further by biological applications. The antibacterial evaluation accounts that [VO(IV)HBDB] shows greater activity than HBDB. DPPH scavenging report demonstrates that [VO(IV)HBDB] exhibits greater antioxidant potential than standard assay. Subsequently, in-vitro antidiabetic activity with α-glucosidase enzyme was also excellent. Molecular docking with α-glucosidase protein of PDB id: 3 WY1 illustrates greater binding energy of about −12.3 kcal/mol defined for [VO(IV)HBDB] than HBDB roughly −7.6 kcal/mol with more amino acid binding residues. The above-disclosed findings of HBDB and its complex firmly sustenance the biochemists and pharmacological field.

SR Spectroscopy in Geochemical Studies of Asphaltenes of Crude Oils from Tatarstan Oil Fields

ESR spectra of asphaltenes from a series of crude oils from the Devonian and Carboniferous deposits of the South-Tatar Dome in Tatarstan with low vanadium content and of vanadiferous crude oils from deposits of the Melekess depression in Tatarstan are analyzed. For asphaltenes from Devonian oils, the correlation between the concentrations of stable free radicals (SFR) and vanadyl complexes (VCs) has direct trend, whereas for asphaltenes from Carboniferous oils the trend is inverse. Taking into account the previously revealed inverse trend for asphaltenes of vanadium-enriched highly viscous crude oils [1], the opposite trends in SFR–VC correlations (direct and inverse) suggest different structures of asphaltene molecules in oils with different vanadium content and, correspondingly, different sources and conditions of the formation of oil deposits. Specific features of the ESR characteristics of asphaltenes of core and extractable oils and of oils from Devonian and Carboniferous deposits are revealed.

Synthesis and Characterization of New Lutidinium Ionic Liquid-Supported Vanadylsalicylaldoxime Complex for Catalytic Application in Epoxidation Reaction.

A new chelating task-specific ionic liquid (TSIL), lutidinium-based salicylaldoxime (LSOH), and its square pyramidal vanadyl(II) complex (VO(LSO)2 ) have been successfully synthesized and structurally characterized using elemental (CHN), spectral, and thermal analyses. The catalytic activity of the lutidinium-salicylaldoxime complex (VO(LSO)2 ) in the alkene epoxidation reactions was studied under various reaction conditions, such as solvent effect, alkene/oxidant molar ratio, pH, reaction temperature, reaction time, and the catalyst dose. The results demonstrated that the CHCl3 solvent, 1 : 3 of the cyclohexene/H2 O2 ratio, pH 8, temperature of 340 K, and catalyst dose of 0.012 mmol are assigned as the optimum conditions for achieving maximum catalytic activity for VO(LSO)2 . Moreover, the VO(LSO)2 complex has the potential for application in the effective and selective epoxidation of alkenes. Notably, under optimal VO(LSO)2 conditions, cyclic alkenes convert more efficiently to their corresponding epoxides than linear alkenes.

Synthesis, spectral, DFT, intrinsic constant of DNA binding and antioxidant activity of vanadyl (IV)2+ complexes of a symmetrical bisthiosemicarbazides

A new series of complexes were prepared by reacting vanadyl (II) sulphate with three multidentate bisthiosemicarbazides, TSCs in search for synthesizing a series of vanadyl complexes to be good candidates for utilization as anti-diabetic drugs. The TSCs 1(H4DDAT), 3 (H4DDET) and 5 (H4DDPT) were characterized by partial elemental analyses, 2DNMR, mass, FTIR and UV–vis. Spectra. The complexes were characterized by elemental analyses (C, H, N, S, M), spectral (FTIR, UV–vis., mass, ESR and XRD), magnetic susceptibility and molar conductivity measurements and assigned the formulae: [(VO)(H4DDAT) (H2O) (OH)]. H2O (2), [(VO)(H4DDET)(SO4)(H2O)].1·5H2O (4) and [(VO)(H4DDPT)(H2O)(SO4)2].2H2O (6). TSC`s were found to bind metal ion in keto or enol/thiol forms as neutral, monobasic or dibasic tridentate and / or hexadentate selective chelate as proved by the data of FTIR and NMR (heteronuclear single quantum coherence (HSQCNMR), correlated spectroscopy (COSY-NMR). UV–vis. and EPR data suggested a square pyramidal arrangement for complex (2) and an octahedral geometry for complexes (4) and (6), respectively. The anisotropic Lande splitting factor evaluated from EPR spectra for the complexes gave values; g|| < g⊥ < ge =2 0.0023. Orbital energy levels for magnetic electrons were determined from theoretically well fitted Spin Hamiltonian parameters. The thermal stability and nature of solvent molecules nature were studied by TGA and DrTGA. XRD data complex (2) suggested a triclinic complex (2); a cubic structure for complex (4) and a monoclinic for complex (6). Molecular modeling evaluated by DFT theory suggested oxygen atoms, N of NH or S of CS groups as donor atoms of TSc moiety and the geometry, Mullikan population, Mullikan charge and HOMO–LUMO gap were computed. Moreover, all compounds were screened for antioxidant activity such as SOD-like activity, scavenging of hydroxyl radicals as well as DNA binding ability.