Dimethyl Sulfoxide Complexes Research Articles

Combination of FTIR and DFT to study the structure and hydrogen-bond properties of alkylammonium-based ILs and DMSO mixtures

Ionic liquids (ILs) are often used in combination with molecular solvents as working fluids in many applications. The addition of molecular solvents disturbs the structure and dynamics of ILs. Thus, understanding the structure and interactions in molecular solvents and IL mixtures is particularly important. In this work, the structure and hydrogen-bond features of N-alkyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide ([N-111n][Tf2N], n = 3, 4, 6 and 8) and dimethylsulfoxide (DMSO) binary systems were studied via the combination of Fourier transform infrared spectroscopy (FTIR) and quantum chemical calculations. The CD systematic stretching vibrational (vs(CD)) region of the methyl groups in DMSO-d6 was specially focused on using excess infrared and two-dimensional correlation spectroscopy. In the mixing process, the DMSO dimer and monomer were gradually reduced with increasing ILs. [N-111n][Tf2N] interacts with DMSO by ion cluster–DMSO-d6 complexes and ion pair–DMSO-d6 complexes. The ion cluster–DMSO complexes gradually increase while the ion pair–DMSO complexes decrease due to the strong electrostatic interaction between the cation and anion. In the interaction complexes, closed-shell, electrostatically dominant and weak strength hydrogen-bonds were found between the ILs and DMSO-d6. The hydrogen atoms in the methyl groups directly attached to the nitrogen atom of the [N-111n]+ cation are the preferred interaction sites of the cations.

Study on Typical Diarylurea Drugs or Derivatives in Cocrystallizing with Strong H-Bond Acceptor DMSO.

Diarylureas are widely used in self-assembly and supramolecular chemistry owing to their outstanding characteristics as both H-bond donors and acceptors. Unfortunately, this bonding property is rarely applied in the development of urea-containing drugs. Herein, seven related dimethyl sulfoxide (DMSO) complexes were screened from 12 substrates involving sorafenib and regorafenib, mainly considering the substitution effect following a robust procedure. All complexes were structurally confirmed by spectroscopic means and thermal analysis. Specially, five cocrystals with three deuterated, named sorafenib·DMSO, donafenib·DMSO, deuregorafenib·DMSO, 6·DMSO, and 7·DMSO were obtained. The crystal structures revealed that all host molecules consistently bonded with DMSO in intermolecular interaction in a 1:1 stoichiometry. However, further comparison with documented DMSO complexes and parent motifs presented some arrangement diversities especially for 6·DMSO which offered a counter-example to previous rules. Major changes in the orientation of meta-substituents and the packing stability for sorafenib·DMSO and deuregorafenib·DMSO were rationalized by theory analysis and computational energy calculation. Cumulative data implied that the planarization of two aryl planes in diarylureas may play a crucial role in cocrystallization. Also, a polymorph study bridged the transformation between these ureas and their DMSO complexes.

Synthesis, characterization, thermal stability, electrochemical behavior, and antioxidant activity of new oxovanadium(iv) and iron(ii) tetradentate Schiff base complexes

Two new tetradentate oxovanadium(IV) and iron(II) Schiff base complexes have been prepared by the interaction of vanadyl(IV) and iron(III) acetylacetonate with the ligand obtained from the reaction of ethylenediamine and 5′-(N-methyl-N-phenylaminomethyl)-2′-hydroxyacetophenone in methanol. These complexes have been characterized by means of different spectroscopic techniques such as UV–visible, FT-IR, mass spectrometry, and elemental analysis. In addition, thermogravimetric (TG) and differential thermogavemetric analysis (DTG) have been utilized to investigate the thermal stability of these complexes. Results showed that both Schiff base complexes decompose in five consecutive stages, and a mechanism has been proposed for each stage of thermal decomposition. Thermogravimetric analysis has been carried out using four different heating rates of 5, 10, 15, and 20 °C min−1, and the kinetic parameters of these complexes have been calculated using the Kissinger method. Cyclic voltammetry has been employed to examine the electrochemical behavior of the two synthesized complexes in dimethyl sulfoxide (DMSO) at a glassy carbon electrode. Each of these complexes displayed one quasi-reversible single electron transfer peak near 0.255 V vs. saturated calomel electrode (SCE) for the V(V)–V(IV) couple and near −0.690 V vs. SCE for the Fe(III)–Fe(II) redox couples, respectively. Finally, the antioxidant activity of the newly prepared complexes has been investigated using the 2,2-diphenyl-1-picrylhydrazyle (DPPH) free radical scavenging assay. Results revealed that the oxovanadium Schiff base complex exhibits good antioxidant activity.

Solvation Behaviour of Some Copper(I) Nitrate Complexes in Dimethylsulfoxide and Nitromethane at 298 K

The ultrasonic velocities of solutions of Bu4NBPh4, Bu4NClO4, [Cu(AN)4]NO3, [Cu(BN)4]NO3, [Cu(Phen)2]NO3, [Cu(DMPhen)2]NO3, [Cu(Bipy)2]NO3 and [Cu(TU)4]NO3 (where AN = acetonitrile, BN = benzonitrile, Phen = 1,10-phenanthroline, DMPhen = 2,9-dimethyl-1,10-phenanthroline, Bipy = 2,2′-bipyridyl and TU = thiourea) were measured in the concentration range 0.03-0.27 M in dimethylsulfoxide (DMSO), nitromethane (NM) and binary mixtures of DMSO + NM containing 0, 20, 40, 60, 80 and 100 mol% NM at 298 K in the present studies. Using ultrasonic velocity and density data, isentropic compressibility (κs) and apparent molal isentropic compressibility (κs,φ) for electrolytes in DMSO + NM mixture have been calculated. Result shows that copper(I) electrolytes show less solvation in NM rich regions indicating structure breaking tendency of nitromethane. Extent of solvation in Cu(I) ions decreases in the order: [Cu(AN)4]+ > [Cu(BN)4]+ > [Cu(TU)4]+ > [Cu(DMPhen)2]+ > [Cu(Phen)2]+ > [Cu(Bipy)2]+.

The microscopic structure of 1-Methoxyethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EOMIMTFSI) during dilution with polar solvents

Ether-functionalized ionic liquids (ILs) have attracted increasing attention in the fields of electrochemistry and energy; however, few fundamental studies of the microscopic properties of ether-functionalized ILs have been reported. In this work, the hydrogen bonding interactions between the ether-functionalized IL 1-methoxyethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EOMIMTFSI) and co-solvents, chloroform (CHCl3), acetonitrile (CH3CN) and dimethyl sulfoxide (DMSO), were investigated at the whole concentration range by Fourier transform infrared spectroscopy (FTIR), excess infrared spectroscopy, and quantum chemical calculations. The following conclusions were made: (1) during dilution with co-solvents, the hydrogen bonding interactions in the three systems were strengthened, and the strength of the hydrogen bonds decreased in the following order: EOMIMTFSI−DMSO > EOMIMTFSI−CHCl3 > EOMIMTFSI−CH3CN. (2) DMSO could disrupt the hydrogen bonding interactions between the cations and anions in EOMIMTFSI, and [EOMIM]+−DMSO complexes were observed in the excess infrared spectrums. CHCl3 and CH3CN were unable to disrupt the electrostatic interactions, and only ion cluster–co-solvent and ion pair–co-solvent complexes were observed. (3) The main interaction sites were different in the studied systems. In the systems of EOMIMTFSI−CHCl3 and EOMIMTFSI−DMSO, the main interaction sites between the co-solvent and cations were C2−H, whereas in the EOMIMTFSI−CH3CN system, the corresponding interaction site was C5−H.

Synthesis and evaluation of 2-pyrrolopyridinylquinoline derivatives as selective tau PET tracers for the diagnosis of Alzheimer's disease

Introduction[18F]THK-5351 was originally developed as a positron emission tomography (PET) imaging tracer for the detection of accumulated tau proteins, the pathological hallmark of Alzheimer's disease (AD). However, clinical studies of [18F]THK-5351 revealed the existence of off-target binding to monoamine oxidase-B (MAO-B). To overcome this off-target binding, in this work, we synthesized and evaluated 2-pyrrolopyridinylquinoline (PPQ) derivatives as selective tau PET imaging tracers. MethodsThe core structure of PPQ derivatives was synthesized mainly using the Buchwald-Hartwig amination coupling reaction. All derivatives were evaluated for binding affinity towards tau and MAO-B by in vitro competitive binding assay. Radiosynthesis of PPQ derivatives was performed by 18F-radiolabeling of their tosylate precursors with activated [18F]KF/Kryptofix222 complex in dimethylsulfoxide by heating at 110 °C for 10 min. The biological properties of these [18F]PPQ derivatives were characterized by in vitro autoradiography of postmortem AD brain sections and by assay of ex vivo biodistribution in mice. ResultsThe PPQ derivatives were synthesized, with yields of 49–84%. In vitro competitive binding assay revealed that two novel PPQ derivatives—PPQ8 and PPQ9—demonstrated high binding affinity for tau (IC50 = 4.9 and 6.9 nM, respectively). The radiosynthesis of [18F]PPQ8 and [18F]PPQ9 yielded 1.4% and 50.1% isolated non-decay corrected radiochemical yield, respectively, with >99% radiochemical purity. The molar radioactivities of [18F]PPQ8 and [18F]PPQ9 were 16.9 and 64.8 GBq/μmol, respectively. The in vitro and ex vivo biological characterization of [18F]PPQ8 and [18F]PPQ9 revealed that these tracers were selective for tau in AD brain sections without off-target binding, and they furthermore demonstrated brain uptake in normal mice. Conclusions18F-labeled PPQ derivatives improved binding affinity and selectivity for tau aggregates in AD. Further structural optimization to improve pharmacokinetics for potent tau PET imaging tracers is required.

Understanding how chlorine additive in a dynamic sequential process affects FA0.3MA0.7PbI3 perovskite film growth for solar cell application

In this work, for the first time, we identify the effect of adding chlorine (Cl) in the dynamic sequential (no stoppage between the sequential steps and the precursor for the second-step is dispensed while the substrate is in motion) solution processing of formamidinium methylammonium lead iodide FA0.3MA0.7PbI3 perovskite solar cells by comparing (i) the roles of two different Cl sources (MACl and FACl) and (ii) the time at which the Cl sources were added: (a) into PbI2-DMSO in the first deposition step or (b) into MAI-FAI in the second deposition step. It is found that Cl in general (regardless of the type of source and at which step it is added) improves the perovskite film with better coverage, better crystallinity, and higher photoluminescence response and longer carrier lifetime due to reduced trap densities. Characterizations for investigating film formation mechanisms reveal that the amount of Cl remaining in the final film is most crucial in determining the film quality. This in turn is controlled by when Cl is added. When Cl is added in the second step, the higher Cl content which is highly diffusive initiates the Dimethyl sulfoxide (DMSO) complex formation and perovskite formation too rapidly producing films with excess PbI2, which are more disorder and have lower crystallinity. FACl exacerbates this while MACl reduces the detrimental effect by slowing down perovskite formation. Therefore, for dynamic sequential processing, it is recommended that MACl is used as the preferred source over FACl and Cl should be added in the 1st step of the process allowing sufficient Cl to leave the film in the 2nd step of the sequential process. The resulting film has better film quality producing a champion device with a 2.8% absolute efficiency increase over the best device fabricated without Cl additives. This work has provided great insights into the film formation mechanism by sequential processing with additive engineering.

Synthesis, characterization and anticancer activity of new 2-acetyl-5-methyl thiophene and cinnamaldehyde thiosemicarbazones and their palladium(II) complexes

New thiosemicarbazone (TSC) ligands, AMT-CN-TSCH (L1), AMT-CN-TSC(CH3) (L2), CIN-CN-TSCH (L3) and CIN-CN-TSC(CH3) (L4) (AMT = 2-acetyl-5-methylthiophene, TSCH = thiosemicarbazide, TSC(CH3) = 4-methyl-3-thiosemicarbazide, CIN = cinnamaldehyde) were synthesized by condensation reaction. The reaction of [PdCODCl2] with the ligands L1, L2 and L4in the ratio 1:1 yielded complexes [Pd(L1)Cl] (C1), [Pd(L2)Cl2] (C2), and [Pd(L4)2Cl2] (C4) respectively (COD = 1,5-cyclooctadiene). The reaction of [Pd(COD)Cl2] with CIN-CN-TSCH (L3) in 1:2 metal to ligand ratio yielded the complex [Pd(L3)2] (C3). The ligands and the complexes were characterized by UV–Vis, FT-IR, NMR, elemental analysis and conductivity measurements. The ligand L1 coordinated to the metal in a tridentate fashion while L2, L3 and L4 coordinated in a bidentate fashion. The ligands L1 and L3 coordinated to the metal as thiol anions while ligand L4 coordinated via the thione sulphur. Conductivity measurements of the metal complexes in dimethyl sulfoxide showed that the chloride ions complexes C1, C2 and C4 are within the coordination spheres. The crystal structures of ligands L2 and L4 were obtained from a Bruker Smart KAPPA APEXII DUO diffractometer with graphite monochromated Mo Kαradiation (k = 0.71073 Å). Cytotoxic activity of the compounds was investigated against the human cancer cell lines; Caco-2 (colon), HeLa (cervical), Hep-G2 (hepatocellular), MCF-7 (breast), PC-3 (prostate) and MCF-12A (non-cancer breast) cells. The complex C2 exhibited excellent broad spectrum growth inhibition activity against all the human cell lines tested except for the non-cancer breast cells. All the metal complexes synthesized inhibited the proliferation of human prostate cancer cell.

Multistep Photochemical Reactions of Polypyridine-Based Ruthenium Nitrosyl Complexes in Dimethylsulfoxide.

The photorelease of nitric oxide (NO·) has been investigated in dimethylsulfoxide (DMSO) on two compounds of formula [Ru(R-tpy)(bpy)(NO)](PF6)3, in which bpy stands for 2,2′-bipyridine and R-tpy for the 4′-R-2,2′:6′,2″-terpyridine with R = H and MeOPh. It is observed that both complexes are extremely sensitive to traces of water, leading to an equilibrium between [Ru(NO)] and [Ru(NO2)]. The photoproducts of formula [Ru(R-tpy)(bpy)(DMSO)](PF6)2 are further subjected to a photoreaction leading to a reversible linkage isomerization between the stable Ru-DMSO(S) (sulfur linked) and the metastable Ru-DMSO(O) (oxygen linked) species. A set of 4 [Ru(R-tpy)(bpy)(DMSO)]2+ complexes (R = H, MeOPh, BrPh, NO2Ph) is investigated to characterize the ratio and mechanism of the isomerization which is tentatively related to the difference in absorbance between the Ru-DMSO(S) and Ru-DMSO(O) forms. In addition, the X-ray crystal structures of [Ru(tpy)(bpy)(NO)](PF6)3 and [Ru(MeOPh-tpy)(bpy)(DMSO(S))](PF6)2 are presented.

Synthesis, Structures, and Photoluminescent Properties of Tricyanidonitridorhenium(V) Complexes with Bipyridine-Type Ligands.

Tricyanidonitridorhenium(V) complexes with 2,2'-bipyridine (bpy) derivatives in which the 4 and 4' positions were substituted by X, [ReN(CN)3(X2bpy)]- (X = NMe2, NH2, OMe, Me, Cl, and Br), were newly synthesized and characterized. The structures of the new complexes were determined by single-crystal X-ray analysis. UV-vis spectra of the complexes in dimethyl sulfoxide (DMSO) showed that the peak maximum wavelengths of rhenium-to-π* bpy-type-ligand charge transfer were in the range of 474-542 nm. Cyclic voltammograms in n-(C4H9)4NPF6-DMSO showed one-electron oxidation and reduction waves corresponding to the Re(VI/V) and X2bpy0/- processes, respectively. The new complexes and [ReN(CN)3bpy]- showed photoluminescence in the crystalline phase at 295 and 80 K and in DMSO at 295 K. The origin of the emission in DMSO was attributed to the triplet nature of the rhenium-to-π* bpy-type-ligand charge-transfer transition. Density functional theory calculations showed that the highest occupied and lowest unoccupied molecular orbitals were primarily localized on the dxy orbital of the rhenium and π* orbitals of the bpy-type ligand, respectively.

Self-Assemblies of Zinc Complexes for Aggregation-Induced Emission Luminogen Precursors.

Positional isomers of zinc–nitrobenzoate complexes possessing pyridine -3-(or-4-) carboxamide are used for a comparative theoretical and experimental study to understand their utility as model complexes to understand the role of metal-to-ligand charge transfer in aggregation-induced emission (AIE). Among the five different model zinc complexes, four of them are non-ionic, and one is an ionic complex. The frontier molecular energy levels of different combinations of the positional isomeric complexes and the absorption maximum were ascertained by density functional theory calculations. The PolyQ value obtained from solid samples of each complex is different. Shifts in the emissions to higher wavelengths than the expected emission for the S1 to S0 transition were observed due to aggregations. The highest value of PolyQ among the complexes was 13.56% observed for emission at 439 nm (λex = 350) of the non-ionic complex, namely, (di-aqua)bis(pyridine-3-carboxamide)di(2-nitrobenzoato)zinc(II) monohydrate. Close resemblance in emission lifetime decay profiles of the solid samples of those complexes and the respective solutions of those complexes in dimethyl sulfoxide with or without water showed a common trend, suggesting aggregation-induced emission in each case. Aggregation-induced emission caused by adding water in dimethyl sulfoxide solution of each complex showed an initial increase without a shift in the emission wavelength followed by a quenching with a shift of the respective emission peak to a short wavelength. Dynamic light scattering studies showed an increase in the average particle sizes upon an increase in the concentration of water. This indicated initial participation of water molecules to form aggregates with the complexes, favoring an increase in the AIE intensity. Aggregation of each complex changes with the concentration of water, and an increase in the concentration of water beyond a characteristic limit causes lowering of the emission intensity to the short wavelength.

Cytotoxicity of photoactivatable bromo tricarbonyl manganese(i) compounds against human liver carcinoma cells.

Two series of photoinduced tricarbonyl manganese(i) compounds were prepared from the reaction of [MnBr(CO)3(2-C(H)[double bond, length as m-dash]O)] (2-C(H)[double bond, length as m-dash]O: quinoline-2-carboxaldehyde and pyridine-2-carboxaldehyde) and para-substituted aniline derivatives (X = OH, OCH3, Cl and NO2). Different electron-donating and electron-withdrawing substituents were introduced in the para-position of the phenyl ring to investigate their influence on the stability of the compounds in the dark and the photophysical properties upon illumination at 525 nm. When kept in the dark, the aerated solutions of the complexes in dimethyl sulfoxide (DMSO) and CH2Cl2 were stable. In the solution, the complexes bearing electron-withdrawing substituents, exchange their bromo ligands with DMSO solvent molecules, as evidenced from infrared and UV/Vis studies as well as time-dependent density functional theory (TDDFT) calculations. The complexes were assessed for their cytotoxicity, both in the dark and upon exposure to a 525 nm LED, against the human hepatocarcinoma cell line (HepG2). A marked reduction in the viability of HepG2 cells treated with the complex functionalized with quinoline and methoxy substituent was observed after illumination in a dose-dependent manner, with an IC50 value of 7.1 μM, making it the most phototoxic compound in our study.

Synthesis of a highly fluorescent N,N‐dimethyl benzylamine–palladium(II) curcuminate complex and its application for determination of trace amounts of water in organic solvents

In this work a new highly fluorescent N,N-dimethyl benzylamine-palladium(II) yu complex was synthesized by the reaction of [Pd2 {(C,N-C6 H4 CH2 N(CH3 )2 }2 (μ-OAc)]2 ] with curcumin. The structure of the synthesized complex was characterized using Fourier transform infra-red (FT-IR) spectroscopy, 1 H nuclear magnetic resonance spectroscopy, and elemental analysis. Fluorescence quantum yield (ΦF ) values of the synthesized complex in dimethyl sulfoxide (DMSO), acetonitrile, ethanol, and methanol were 0.160, 0.104, 0.068, and 0.061, respectively. The fluorescence signal of the complex in the organic solvents was very sensitive to the water content of the organic solvent. The quenching effect of water was used to determine trace amounts of water in the heteroatom-containing organic solvents (ethanol, methanol, acetonitrile) and redox-active solvents (DMSO). The linear ranges for determination of water (v/v %) in ethanol, DMSO and acetonitrile were found to be 0.03-14.5, 0.08-13.8, and 0.07-18.8, respectively. Two linear ranges were found for determination of water (v/v %) in methanol (0.1-1.2 and 4.7-25.0). Detection limit (DL) values were calculated to be 0.001, 0.05, 0.004, and 0.01 (v/v %) in ethanol, methanol, acetonitrile, and DMSO, respectively. The proposed method overcomes the problems of the standard Karl Fischer method for determination of water in DMSO. In addition, it gave the best DL value for determination of water in ethanol compared with all published papers to date.

Low-dimensional compounds containing bioactive ligands. Part XII: Synthesis, structures, spectra, in vitro antimicrobial and cytotoxic activities of zinc(II) complexes with halogen derivatives of quinolin-8-ol

Seven new zinc(II) complexes, K[Zn(dClQ)3]·2DMF (1), K[Zn(dClQ)3]·2DMF·H2O (2), [Zn(dBrQ)2(H2O)]2·DMF·H2O (3), [Zn(BrQ)2(H2O)]2·H2O (4), (HdClQ)2[ZnCl4]·2H2O (5), [Zn(dClQ)2(H2O)2]·H2O (6) and [Zn(CQ)2(H2O)2] (7) (5,7-dichloroquinolin-8-ol (dClQ), protonated 5,7-dichloroquinolin-8-ol (HdClQ), 5,7-dibromoquinolin-8-ol (dBrQ), 7-bromoquinolin-8-ol (BrQ), 5-chloro-7-iodoquinolin-8-ol (CQ)) have been prepared. All complexes were characterized by IR spectroscopy, elemental analysis and, except 7, by X-ray structure analysis. Stability of complexes in dimethyl sulfoxide was verified by NMR spectra. Antimicrobial activity was tested against nine strains of pathogenic bacteria, five mould species and two yeast species. Cytotoxic activity was tested against colon cancer cell line HCT 116 and non-cancerous cell line CCD-18Co. While all complexes showed higher cytotoxicity than cisplatin, poor selectivity to normal cells was observed.

Novel 13,14‐dimethyl‐5,8‐dioxa‐2,11,13,14‐tetraaza‐1,12‐diphosphabicyclo [10.1.1] tetradecane 1,12‐dioxide ligand and its Ni(II), Co(II), and Cu(II) complexes: Synthesis, characterization, antimicrobial, DNA cleavage, and computational studies

A novel diazadiphosphetidine ligand derived from the reaction of 2,4‐dichloro‐1,3‐dimethyl‐1,3,2,4‐diazadiphosphetidine‐2,4‐dioxide and 2,2′‐(ethane‐1,2‐diylbis[oxy])bis(ethan‐1‐amine) and its Ni(II), Cu(II), and Co(II) complexes have been synthesized, characterized by spectroscopic, elemental analyses, magnetic susceptibility, and conductivity methods, and screened for antimicrobial, DNA binding, and cleavage properties. Spectroscopic analysis and elemental analyses indicate the formula [M(H2L)Cl2] for the Cu(II), Co(II), Ni(II), and Zn(II) complexes and octahedral geometry for all the complexes. The non‐electrolytic nature of the complexes in dimethyl sulfoxide (DMSO) was confirmed by their molar conductance values, which are in the range 12.32–6.73 Ω−1 cm2 mol−1. Computational studies have been carried out at the density functional theory (DFT)‐B3LYP/6‐31G(d) level of theory on the structural and spectroscopic properties of diazadiphosphetidine H2L and its binuclear Cu(II), Co(II), Ni(II), and Zn(II) complexes. Six tautomers and geometrical isomers of the diazadiphosphetidine ligand were confirmed using semiempirical AM1 and DFT method from DMOL3 calculations. The copper complex had the best antibacterial activity against Staphylococcus aureus (ATCC 29213). DNA cleavage activities of the compounds, evaluated on pBR322 DNA by agarose gel electrophoresis in the presence and absence of an oxidant (H2O2) and a free‐radical scavenger (DMSO), indicated no activity for the ligand and moderate activity for the complexes, with the copper complex cleaving pBR322 DNA more efficiently in the presence of H2O2.

Reactivity and Transformation of Antimetastatic and Cytotoxic Rhodium(III)-Dimethyl Sulfoxide Complexes in Biological Fluids: An XAS Speciation Study.

Rhodium(III) anticancer drugs can exert preferential antimetastatic or cytotoxic activities, which are dependent on subtle structural changes. In order to delineate factors affecting the biotransformations and speciation, mer,cis-[RhCl3( S-dmso)2( O-dmso)] (A1) and mer,cis-[RhCl3( S-dmso)2(2N-indazole)] (A2) have been studied by X-ray absorption spectroscopy (XAS). Interactions of these complexes with saline buffer, cell culture media, serum proteins (albumin and apo-transferrin), native and chemically degraded collagen gels, and A549 cells have been studied using linear combination fitting (LCF) and 3D scatter plots of XAS data. Following initial aquation and hydrolysis reactions involving stepwise displacement of Cl- and S-/ O-dmso ligands, the Rh(III) complexes underwent further ligand substitution reactions with biological nucleophiles (e.g., amino acid residues of serum proteins). The reaction of A1 with chemically degraded collagen gel was postulated to be a key reason for its antimetastatic activity. Analyses of the XAS of Rh-treated bulk cells were consistent with structure-reactivity relationships in which the more reactive A1 was predominantly antimetastatic and the less reactive A2 was predominantly cytotoxic, showing relationships parallel to typical Ru(III) anticancer agents, i.e., NAMI-A ([ImH] trans-[RuCl4( S-dmso)( N-imidazole)2], ImH = imidazolium cation) and KP1019/NKP1339 (KP1019, [IndH] trans-[RuCl4(N-indazole)2], IndH = indazolium cation; NKP1339, sodium trans-[RuCl4(2N-indazole)2]), respectively.

Ruthenium(II) dimethylsulfoxide complex with pyrazole/dithiocarbazate ligand

The aim of the study was to synthesize and characterize a new ruthenium(II)-pyrazole/dithiocarbazate complex derived from cis-[RuCl2(dmso)4] (Ru-dmso) and coordinated with 3-methyl-5-phenyl-pyrazoline-1-(S-benzyl)dithiocarbazate (dtc). The reaction of Ru-dmso with the dtc ligand was performed with equimolar amount, resulting in a neutral monosubstituted complex [RuCl2(dmso)3(dtc)] (Ru-dtc).To characterize this complex, conductivity measurements and spectroscopic techniques (1H-NMR, FTIR, UV–Vis, ESI–MS) were applied. Thermogravimetric analysis (TG) and differential thermal analysis were used to identify the changes in the thermal decompositions. The molar conductivity in methanol indicates that this complex is nonelectrolyte. Mass spectra showed m/z peak at 697, with a typical isotope pattern of ruthenium, which can be assigned to fragments of [RuCl(dmso)3(dtc)]+. The chemical shifts of dmso resonances in both ruthenium complexes have been compared and indicated that O-dmso from the precursor was substituted by the dithiocarbazate derivative in the Ru-dtc. The FTIR spectrum shows that this coordination was achieved through the N-pyrazole ring. Moreover, spectrophotometric titrations by the addition of increasing concentrations of triethanolamine or acetic acid to the dtc ligand and Ru-dtc complex enabled the determination of constant equilibrium from the absorbance changes in the visible band region. Moreover, density functional theory (DFT) calculations were applied to evaluate the electronic properties, while time-dependent DFT was applied to clarify UV–Vis results. Finally, the thermal data reveal various steps of decomposition of the ruthenium complexes, producing RuO2 as final residue.

Direct detection of polar structure formation in helium nanodroplets by beam deflection measurements.

Long-range intermolecular forces are able to steer polar molecules submerged in superfluid helium nanodroplets into highly polar metastable configurations. We demonstrate that the presence of such special structures can be identified, in a direct and determinative way, by electrostatic deflection of the doped nanodroplet beam. The measurement also establishes the structures' electric dipole moments. In consequence, the introduced approach is complementary to spectroscopic studies of low-temperature molecular assembly reactions. It is enabled by the fact that within the cold superfluid matrix the molecular dipoles become nearly completely oriented by the applied electric field. As a result, the massive (tens of thousands of helium atoms) nanodroplets undergo significant deflections. The method is illustrated here by an application to dimers and trimers of dimethyl sulfoxide (DMSO) molecules. We interpret the experimental results with ab initio theory, mapping the potential energy surface of DMSO complexes and simulating their low temperature aggregation dynamics.

Synthesis, structural characterization, antimicrobial, antioxidant and DNA binding studies of some novel homo‐binuclear Schiff base metal (II) complexes

A novel bi‐nucleating Schiff base ligand, 6,6′‐(((1E,1′E)‐thiophene‐2,5‐diylbis (methaneylylidene))bis (azaneylylidene))bis (3,4‐dimethylaniline), and five binuclear M (II) complexes were synthesized. The bi‐nucleating Schiff base ligand and its metal complexes were characterized using various physicochemical techniques, e.g. elemental analyses, spectroscopic methods, conductivity and magnetic moment measurements. The low molar conductance of the complexes in dimethylsulfoxide shows their non‐electrolytic nature. The antibacterial activities were screened against pathogenic bacteria (Staphylococcus aureus, Escherichia coli, Pseudomonas putida and Bacillus subtilis). The antifungal activity was screened against Aspergillus niger, Aspergillus flavus and Rhizoctonia bataicola. The antimicrobial activity data showed that the metal complexes are more potent than the parent Schiff base ligand against microorganisms. The antioxidant activities of the synthesized compounds were investigated through scavenging activity against 2,2‐diphenyl‐2‐picrylhydrazyl, superoxide anion, hydroxyl and 2,2′‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonic acid) radicals. The complexes have superior radical scavenging activity than the free ligand and the scavenging effects of the Cu (II) complex are stronger than those of the other complexes. DNA binding studies were performed using electronic spectroscopy, fluorometric competition studies and viscosity measurements. The data indicated that there is a marked enhancement in biocidal activity of the ligand under similar experimental conditions because of coordination with metal ions.

Osmium Dimethyl Sulfoxide Complexes. Crystal Structure of the Complex [H(DMSO)2][OsIIIBr4(DMSO)2

X-ray diffraction is used to study complex [H(DMSO)2][OsBr4(DMSO)2] (1). The compound crystallizes in the triclinic crystal system, space group Pī, unit cell parameters are as follows: a = 8.5942(3) A, b = 8.7621(3) A, c = 16.0193(6) A, V = 1072.25(7) A3, α = 76.3740(10)°, β = 75.6060(10)°, γ = 68.3790(10)°, Z = 2, R = 0.0270.