Photochromic transformations of amphiphilic spiropyran in acetonitrile solutions and at the air/water interface

Russian Chemical Bulletin - The results of a study of the photochromic properties of 1´-hexadecyl-3´,3´-dimethyl-6-nitro-1´,3´-dihydrospiro[chromene-2,2´-indole] (SP)...     

Influence of the number of anchor groups on the photophysical properties of coordination compounds as components of dye-sensitized solar cells

The geometry, electronic structure and properties, and composition of frontier molecular orbitals of the Fe^II complex with 4,4´,4´´,4´´´-substituted 2,2´:6´,2´´:6´´,2´´´-quaterpyridine were examined using quantum chemical simulation. This compound was proposed for use as a photoactive component in dye-sensitized solar cells. The regularities were established of the influence of the number of carboxyl groups in the molecular structure on the composition and energy of the frontier orbitals determining the electronic absorption spectra of the studied compounds. The presence of two COOH groups in the structure of the studied complex is the most optimal for use as a sensitizer.     

Quantum chemical modeling of 2,2´-bipyridine-6,6´-dicarboxylic acid diamide structures: a relationship between the extraction ability and conformational behavior of the ligands

Russian Chemical Bulletin - Approaches to the theoretical evaluation of a comparative affinity to metal ions of 2,2´-bipyridine-6,6´-dicarboxylic acid diamides, which are new promising...     

Iron(II) and ruthenium(II) complexes with polypyridine derivatives as sensitizers for DSSC: the structure and spectral properties,as studied by quantum chemistry methods

Density functional calculations of the geometries, electronic structures, and spectral properties of a series of iron(II) and ruthenium(II) complexes with 4,4´,4´,4´´-substituted 2,2´:6´2´´:6´´,2´´´-quaterpyridines were carried out. A high-spin state is characteristic of the iron(II) complexes with Cl^–, NO^–, CNS^–, and I^– as axial ligands while a low-spin state is characteristic of the iron(II) complex with a CN^– axial ligand. Calculations of the complexes with the nitroxide ligand predict intense absorption in a wide wavelength range up to the IR region.     

Synthesis of a tetrapyrazinoporphyrazine-based fluorescent sensor for detection of Cu<Superscript>2+</Superscript> ion

In this study, a novel tetrapyrazinoporphyrazine-based fluorescent sensor for Cu²⁺ ion was synthesized and fully characterized by ¹H NMR, MALDI-TOF MS, and elemental analysis. A tetrapyrazinoporphyrazine substituent was used as the reporting group and a 2,2′-dipyridylamine moiety was employed as the recognition group. The effects of various metal ions on the absorption and emission spectra of the designed molecule were investigated, demonstrating that this compound shows selectivity and sensitivity toward the Cu²⁺ ion. Upon addition of Cu²⁺ ion, a fluorescent intensity of the tetrapyrazinoporphyrazine-based sensor decreased gradually at 655 nm. To confirm a selective binding ability of 2,2′-dipyridylamine moiety toward Cu²⁺ ion, a comparative study was performed using tetrapyrazinoporphyrazine derivative with bromine instead of 2,2′-dipyridylamine moiety. Furthermore, association constant and detection limit value of the synthesized compound toward Cu²⁺ ion were derived from a repetitive titration experiment. Also, a reversibility of the prepared sensor was confirmed through additional test using compound and ethylenediaminetetraacetic acid.     

Heteroleptic ruthenium bioflavonoid complexes: from synthesis to in vitro biological activity

Heteroleptic ruthenium(II) bioflavonoid complexes of quercetin, morin, chrysin, and 3-hydroxyflavone were prepared and their interaction with CT DNA and BSA along with antioxidant and in vitro anticancer and antimicrobial activities was investigated. The formulation and characterization of complexes were achieved through elemental and thermal analysis, mass spectrometry, ¹H NMR spectroscopy along with infrared, electronic absorption, and emission spectroscopy as well as square-wave voltammetry, and magnetic and conductivity measurements. Ruthenium(II) is octahedrally coordinated in cationic complex species to two bidentate diimine ligands (2,2′-bipyridine or 1,10-phenanthroline) and one bidentate monobasic flavonoid ligand through 3,4-site of quercetin, morin, and 3-hydroxyflavone or 4,5-site of chrysin. Complexes bind CT DNA by intercalation and binding constants comparable to ethidium bromide or 10 times higher. Binding constants of complexes to BSA were several times higher compared to ibuprofen and diazepam, and suggest that the complexes have a strong affinity to BSA. Antioxidant activity tests showed that the complexes are more potent in terms of radical inhibition compared to the parent flavonoids. Cytotoxic testing revealed that the Ru(II) complex of quercetin with 2,2′-bipyridine co-ligand has good selectivity to breast adenocarcinoma, while the complex of 3-hydroxyflavone with 2,2′-bipyridine co-ligand showed strong cytotoxicity toward all tested cell lines with IC₅₀ ～ 1 μM. All complexes showed moderate activity toward Acinetobacter baumannii, while the Ru(II) complex of 3-hydroxyflavone with 2,2′-bipyridine showed excellent activity toward MRSA and Candida albicans.     

The electronic spectrum of (−)-s-(ps)-2,5,3',6'-tetrahydro[2.2]paracyclophane-2-carboxylic acid

A new, efficient route was used in the synthesis of [2,2]paracyclophane-2-carboxylic acid. The chiral acid was then resolved and the Birch reduction performed yielding one enantiomer of tetrahydro[2,2]paracyclophane-2-carboxylic acid. The UV spectrum of tetrahydro[2,2]paracyclophane-2-carboxylic acid in isopentane shows one absorption at 206 nm (?_max=5271). There are three bands observed in the CD spectrum in isopentane at 236 nm ([θ] = 1.8 × 10⁴), 201 nm ([θ]=-16×10⁴) and a positive band indicated below 180 nm but not observed, in ethanol the CD spectrum exhibits a band at 205 nm ([θ]= 1.5×10⁴) and the UV spectrum shows a band at 208 nm (?_max=5915). The bands were assigned and possible reasons for the occurrence of a π→π^* transition at unexpectedly long wavelengths are discussed.     

Cadmium(II) complexes with monoiodo- and dibromodipyrromethenes: synthesis,molecular structure,spectral-luminescent properties,and stability in solutions

Cadmium(II) chelates with 4-iodo-, 5,5´-, and 4,4´-dibromo-2,2´-dipyrromethenes (HL¹, HL², and HL³, respectively) with the composition of [CdL₂] were synthesized. The influence of structural features of their molecules and properties of the medium on the characteristics of absorption and fluorescence spectra, and also on the thermodynamic stability constants in solutions was evaluated. The results of quantum chemical calculations revealed that the additional coordination interactions between the bromine atoms at the α-positions of dipyrromethene ligands and the complexing atom are possible in the molecular structure of α,α´- dibromosubstituted dipyrromethenate [Cd(L²)₂] in contrast with β-halogenated analogues [Cd(L¹)₂] and [Cd(L³)₂].     

9,9′‐spirobifluorene‐containing polycarbonates: Transparent polymers with high refractive index and low birefringence

Syntheses of 2,2′‐bisalcoholic group‐substituted 9,9′‐spirobifluorene monomers 2 were performed by the reaction of 2,2′‐dihydroxy‐9,9′‐spirobifluorene 2a with haloalcohols. Polycarbonates consisting of 9,9′‐spirobifluorene skeleton in the main chain (PC 4 ) were synthesized by the polycondensation of 2,2′‐bisalcoholic monomers 2 and triphosgene or diphenyl carbonate. PC 4 showed good thermal stability: the 5% weight loss temperature was over 330 °C under both nitrogen and air atmospheres. The glass transition temperature was in a range of 16–269 °C estimated by differential scanning calorimetry, depending on the flexibility of the alkylene or oxyethylene chains of 2 . PC 4 showed high solubility toward ordinary organic solvents such as CHCl₃, benzene, and THF, making possible the preparation of the flexible thin films. Very high refractive index in a range of 1.62–1.66 at 589 nm was observed although PC 4 consists only of C, H, and O atoms, whereas very low degree of birefringence was confirmed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3658–3667, 2010     

Synthesis,Crystal Structure,and Electrochemical Properties of One Polyoxometalate-Based Silver(I) Compound with Keggin-Type [PW<Subscript>12</Subscript>O<Subscript>40</Subscript>]<Superscript>3−</Superscript> Anions

One polyoxometalate-based silver(I) compound [Ag(2,2'-Bipy)₂]₃(PW₁₂O₄₀) (I) (2,2'-Bipy = 2,2'- bipyridine) has been synthesized and structurally characterized by IR spectroscopy, elemental analysis, XRPD and X-ray single-crystal structure analysis (CIF file CCDC no. 1572216). Compound I exhibits a crystalline three-dimentional supramolecular framework constructed by Ag-2,2'-Bipy coordination units and [PW₁₂O₄0]^3? template anions, in which there are multiform π...π interactions and hydrogen bonds. The cyclic voltammetric experiments show that compound I displays a good electrocatalytic activity toward the reduction of nitrite.     

Facile synthesis of 2-benzoxazoles via CuI/2,2'-bipyridine catalyzed intramolecular C–O coupling of 2-haloanilides

Development of newer methods for the synthesis of Benzoxazoles has of greater interest due to their wide range of biological activities and pharmaceutical importance. We herein report a facile and general method for the synthesis of 2-substituted Benzoxazoles via copper catalyzed intramolecular C–O cross-coupling of 2-haloanilides. A combination of CuI (5?mol%), 2,2'-bipyridine (10?mol%), Cs₂CO₃ (2 equiv.) in DMF solvent with 4?Å molecular sieves at 140?°C, illustrated the scope for tuning the reactivity of 2-haloanilides toward the selective formation of a series of 2-alkyl benzoxazole derivatives in moderate to good yields. This is the first systematic study using CuI/2,2'-Bipyridine as the catalytic system for the synthesis of 2-substituted Benzoxazoles. The outcome of the reaction was found to be significantly influenced by the aromatic and amide substituents of 2-haloanilides.     

A Novel Fiber with Phenyl-Functionalized MSU (Michigan State University) Coating for Solid-Phase Microextraction Combined with High Performance Liquid Chromatography for Preconcentration and Determination of Trace Polychlorinated Biphenyls in Environmental Water Samples

A novel and robust phenyl-functionalized MSU-1 (Ph-MSU) coated fiber for solid-phase microextraction (SPME) coupled to high performance liquid chromatography (HPLC) was developed for the preconcentration and the determination of 2,4,4′-trichlorobiphenyl (PCB 28), 2,4′,5-trichlorobiphenyl (PCB 31), 2,2′,5,5′-tetrachlorobiphenyl (PCB 52), 2,2′,4,5,5′-pentachlorobiphenyl (PCB 101), 2,3′,4,4′,5-pentachlorobiphenyl (PCB 118), 2,2′,3,4,4′,5′-hexachlorobiphenyl (PCB 138), 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153), and 2,2′,3,4,4′,5,5′-heptachlorobiphenyl (PCB 180) in environmental water samples. Experimental conditions affecting SPME were examined in detail. The Ph-MSU coating provided large porosity and short-range mesostructures necessary for high extraction capacity and rapid mass transfer of PCBs. The Ph-MSU coated fiber exhibited selectivity for PCB 28, PCB 31, PCB 118, and PCB 138 in a limited extraction time. Good linearity for all PCBs was obtained with correlation coefficients from 0.9987 to 0.9994. The recoveries were within 94.3% to 103% for the spiked water with 300 ng · L^?1 per PCB. The relative standard deviations (RSDs) ranged from 3.10% to 6.23% and the limits of detection (LODs) were between 8.73 ng · L^?1 and 13.8 ng · L^?1. The proposed method was applied for the determination of PCBs in real river water and rainwater samples. The median recoveries ranged from 85.6% to 118% with RSDs between 4.23% and 8.78%. The experimental results demonstrated that the Ph-MSU fiber coating could be reused for over 250 times without loss of the extraction efficiency. These results clearly indicate that the Ph-MSU coated fiber was rapid, sensitive, and suitable for the preconcentration and determination of trace PCBs in environmental water samples.     

Study of the reactivity of organonickel sigma-complexes towards nitriles

The reactivity of organonickel sigma-complexes of type [NiBr(Ar)(bpy)], where Ar = 2,6-dimethylphenyl (Xyl), 2,4,6-trimethylphenyl (Mes), 2,4,6-triisopropylphenyl (Tipp), 2,4,6-tricyclohexylphenyl (Tchp), bpy = 2,2´-bipyridine, towards nitriles (acetonitrile, propionitrile, chloroacetonitrile, benzonitrile) has been investigated. This reaction leads to imines by formation of new carbon—carbon bond between aromatic fragment and nitrile group C≡N.     

Synthesis of guanidine‐containing copolymers and their applications in the sorption of transition metals

2,2‐Diallyl‐1,1,3,3‐tetraethylguanidinium chloride copolymers with N‐substituted maleimides have been prepared by free radical copolymerization. Specific surface area and porosity of the copolymers under investigation have been determined by using the low‐temperature adsorption method. Sorption capacity of the copolymers toward Re(VII), Mo(VI), Ni(II) and Cu(II) ions has been investigated. The influence of treatment time, temperature and pH on sorption of metal ions was studied. Copyright © 2016 John Wiley & Sons, Ltd.     

Li⁺ selective podand-type fluoroionophore based on a diphenyl sulfoxide derivative bearing two pyrene groups

New podand-type fluoroionophores having two pyrene moieties: 2,2′-bis(1-pyrenylacetyloxy)diphenyl sulfide (3), 2,2′-bis(1-pyrenylacetyloxy)diphenyl sulfoxide (4), and 2,2′-bis(1-pyrenylacetyloxy)diphenyl sulfone (5), have been synthesized by connecting two 1-pyrenecarbonylmethyl groups with the two hydroxy groups of 2,2′-dihydroxydiphenyl sulfide, sulfoxide, and sulfone, respectively. Their complexation behavior toward alkali metal ions was examined by fluorescence spectroscopy. Among these fluoroionophores, compound 4, having a sulfinyl group, showed high selectivity toward Li?.     

Monomer-isomerization radical polymerization of di-tert-butyl maleate and preparation of poly(fumaric acid) via pyrolysis

Di-tert-butyl maleate (DtBM) did not polymerize with 2,2′-azobis(isobutyronitrile) as a radical initiator, but DtBM easily homopolymerized via a monomer-isomerization radical polymerization mechanism to give a high molecular weight polymer when morpholine was added into the polymerization system as an isomerization catalyst. The feature of the monomer-isomerization polymerization of DtBM was investigated in detail. The polymer obtained was confirmed to consist of a poly(tert-butoxycarbonylmethylene) structure similar to that from di-tert-butyl fumarate. Subsequent pyrolysis of the resulting polymer at 180°C is a useful route to synthesis of a high molecular weight poly(fumaric acid). © 1993 John Wiley & Sons, Inc.     

Hydrogen-bonded assemblies of a new polyoxometalate-based 3-D supramolecular architecture

A new hydrogen-bonded 3-D supramolecular architecture [Ni(2,2′-bpy)₃]_1.5[AsW^VI ₁₀W^V ₂O₄₀Ni(2,2′-bpy)₂(H₂O)]·0.5H₂O (2,2′-bpy?=?2,2′-bipyridine) (1) has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis, PXRD, elemental analysis, XPS, and IR spectrum. Compound 1 exhibits photocatalytic activity for methylene blue degradation under visible-light irradiation and shows good stability toward visible-light photocatalysis. Luminescence of 1 is also reported.     

Synthesis of SnO<Subscript>2</Subscript>–MoO<Subscript>3</Subscript> solid solution and its properties in the reaction of methanol dehydrogenation

X-ray diffraction analysis, synchronous-thermal analysis, and IR spectroscopy were used to confirm the possibility of obtaining a tin–molybdenum solid solution by the closed-cycle technology via joint mechanochemical activation of tin oxide (SnO₂) and molybdenum oxide (h-MoO₃), followed by a thermal treatment at 650°C. An analysis of the catalytic properties demonstrated that various target reaction products (methyl formate and formaldehyde) can be obtained by varying the temperature of the methanol dehydrogenation process. It was found that the selectivity toward methyl formate reaches a maximum of 99.88% at a temperature of 180°C. Raising the temperature further results in that the selectivity toward formaldehyde increases and reaches its maximum value at 260°C.     

Poly(2‐oxazoline) hydrogels crosslinked with aliphatic bis(2‐oxazoline)s: Properties,cytotoxicity, and cell cultivation

A series of hydrogels from 2‐ethyl‐2‐oxazoline and three bis(2‐oxazoline) crosslinkers—1,4‐butylene‐2,2′‐bis(2‐oxazoline), 1,6‐hexamethylene‐2,2′‐bis(2‐oxazoline), and 1,8‐octamethylene‐2,2′‐bis(2‐oxazoline)—are prepared. The hydrogels differ by the length of aliphatic chain of crosslinker and by the percentage of crosslinker (2–10%). The influence of the type and the percentage of the crosslinker on swelling properties, mechanical properties, and state of water is studied. The equilibrium swelling degree in water ranges from 2 to 20. With a proper selection of the crosslinker, Young's modulus can be varied from 10 kPa to almost 100 kPa. To evaluate the potential for medical applications, the cytotoxicity of extracts and the contact toxicity toward murine fibroblasts are measured. The hydrogels with the crosslinker containing a shorter aliphatic exhibit low toxicity toward fibroblast cells. Moreover, the viability and the proliferation of pancreatic β‐cells incubated inside hydrogels for 12 days are analyzed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1548–1559     

Effect of dimethyl sulfoxide on electrochemical and antiradical properties of ascorbic acid

Solvent effect of dimethyl sulfoxide (DMSO) on the oxidation-reduction properties of ascorbic acid (AA) was studied by the electroanalytical method of differential pulse voltammetry (DPV) in a three-electrode cell at 37 °C. Dimethylsulfoxide was found to considerably decrease the oxidation ability of AA due to the formation of molecular complexes between AA and DMSO through the intermolecular hydrogen bonds and shift the anodic peak potential toward the positive values, with its intensity being decreased. Kinetic spectrophotometric measurements in the UV-vis regions of the reaction of the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH^·) with AA confirmed the stabilizing effect of the Lewis base DMSO on the reactivity of the neutral form of AA and its intermediates with respect to DPPH^·. The mechanism of oxidation of AA with the radical DPPH· in the presence of DMSO was considered.