Luminescent Complexes of Europium (III) with 2-(Phenylethynyl)-1,10-phenanthroline: The Role of the Counterions

New antenna ligand, 2-(phenylethynyl)-1,10-phenanthroline (PEP), and its luminescent Eu(III) complexes, Eu(PEP)2Cl3 and Eu(PEP)2(NO3)3, are synthesized and characterized. The synthetic procedure applied is based on reacting of europium salts with ligand in hot acetonitrile solutions in molar ratio 1 to 2. The structure of the complexes is refined by X-ray diffraction based on the single crystals obtained. The compounds [Eu(PEP)2Cl3]∙2CH3CN and [Eu(PEP)2(NO3)3]∙2CH3CN crystalize in monoclinic space group P21/n and P21/c, respectively, with two acetonitrile solvent molecules. Intra- and inter-ligand π-π stacking interactions are present in solid stat and are realized between the phenanthroline moieties, as well as between the substituents and the phenanthroline units. The optical properties of the complexes are investigated in solid state, acetonitrile and dichloromethane solution. Both compounds exhibit bright red luminescence caused by the organic ligand acting as antenna for sensitization of Eu (III) emission. The newly designed complexes differ in counter ions in the inner coordination sphere, which allows exploring their influence on the stability, molecular and supramolecular structure, fluorescent properties and symmetry of the Eu (III) ion. In addition, molecular simulations are performed in order to explain the observed experimental behavior of the complexes. The discovered structure-properties relationships give insight on the role of the counter ions in the molecular design of new Eu (III) based luminescent materials.

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Two- and three-dimensional coordination polymers based on zinc(II) and furan-2,5-dicarboxylic acid: structure variation due to metal-to-linker ratio

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229618015759 ◽

2018 ◽

Vol 74 (12) ◽

pp. 1719-1724 ◽

Cited By ~ 1

Author(s):

Yimin Mao ◽

Peter Y. Zavalij

Keyword(s):

Dicarboxylic Acid ◽

Coordination Polymers ◽

Three Dimensional ◽

Molar Ratio ◽

Monoclinic Space Group ◽

Structure Variation ◽

Space Group ◽

Hydrogen Bonding Pattern ◽

Solvent Molecules ◽

A Chain

Two ZnII-based coordination polymers (CPs) were synthesized by the hydrothermal method, using Zn(NO3)2·6H2O and furan-2,5-dicarboxylic acid (FDCA) in dimethylformamide (DMF) solvent, at 95 °C. Poly[tetrakis(dimethylazanium) [tetrakis(μ2-furan-2,5-dicarboxylato-κ2 O 2:O 5)dizinc(II)]], {(C2H8N)4[Zn2(C6H2O5)4]} n or {[DMA]4[ZnII 2(FDC)4]} n (DMA = dimethylazanium and FDC = furan-2,5-dicarboxylate), (1), was obtained with a 1:1 molar ratio of ZnII and FDCA. It crystallized in the monoclinic space group C2/c. Coordinated by ZnII ions, FDC2− ligands form 21 double-stranded helices propagating along the b axis. The helices are interconnected and extend laterally in the a direction, forming a two-dimensional (2D) sheet-like network. The 2D sheets are stacked along the c direction without interconnections. DMA cations are cocrystallized in (1) and are hydrogen bonded with carboxylate O atoms of the FDC2− ligands. The hydrogen-bonding pattern consists of R 2 2(4) and R 2 2(10) motifs alternating in a chain. Poly[bis(dimethylazanium) [bis(μ4-furan-2,5-dicarboxylato-κO 2:κO 2′:κO 5:κO 5)bis(μ3-furan-2,5-dicarboxylato-κO 2:κO 2′:κO 5)dizinc(II)] dimethylformamide 3.08-solvate], {(C2H8N)2[Zn2(C6H2O5)4]·3.08C3H7NO} n or {[DMA]2[ZnII 3(FDC)4]·3.08DMF} n , (2), was obtained with a 1:2 molar ratio of ZnII and FDCA. It crystallized in the monoclinic space group P21/c, forming a three-dimensional network. The pores are filled with DMA cations and DMF solvent molecules.

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A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽

10.32964/tj8.1.20 ◽

2009 ◽

Vol 8 (1) ◽

pp. 20-26 ◽

Cited By ~ 1

Author(s):

PEEYUSH TRIPATHI ◽

MARGARET JOYCE ◽

PAUL D. FLEMING ◽

MASAHIRO SUGIHARA

Keyword(s):

Boundary Layer ◽

Experimental Design ◽

High Speed ◽

Statistical Study ◽

Process Variables ◽

High Speeds ◽

The Stability ◽

Air Removal ◽

Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

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Divergence entropy to characterize the stability in selected enzymes – The role of disulfide bonds in respect to the structure of hydrophobic core

10.3390/ecea-2-b009 ◽

2015 ◽

Author(s):

Irena Roterman ◽

Mateusz Banach ◽

Leszek Konieczny ◽

Barbara Kalinowska

Keyword(s):

Disulfide Bonds ◽

Hydrophobic Core ◽

The Stability

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The Role of Hydrophobicity in the Stability and pH-Switchability of (RXDX)4 and Coumarin-RXDX Conjugate β-Sheets

10.26434/chemrxiv.11493060 ◽

2020 ◽

Author(s):

Ryan Weber ◽

Martin McCullagh

Keyword(s):

Biological Imaging ◽

Ph Sensing ◽

Hydrophobic Residue ◽

Ideal Candidate ◽

Self Assembling ◽

Sensing Applications ◽

Β Sheets ◽

The Stability ◽

Dynamics Simulations

pH-switchable, self-assembling materials are of interest in biological imaging and sensing applications. Here we propose that combining the pH-switchability of RXDX (X=Ala, Val, Leu, Ile, Phe) peptides and the optical properties of coumarin creates an ideal candidate for these materials. This suggestion is tested with a thorough set of all-atom molecular dynamics simulations. We first investigate the dependence of pH-switchabiliy on the identity of the hydrophobic residue, X, in the bare (RXDX)4 systems. Increasing the hydrophobicity stabilizes the fiber which, in turn, reduces the pH-switchabilty of the system. This behavior is found to be somewhat transferable to systems in which a single hydrophobic residue is replaced with a coumarin containing amino acid. In this case, conjugates with X=Ala are found to be unstable and both pHs while conjugates with X=Val, Leu, Ile and Phe are found to form stable β-sheets at least at neutral pH. The (RFDF)4-coumarin conjugate is found to have the largest relative entropy value of 0.884 +/- 0.001 between neutral and acidic coumarin ordering distributions. Thus, we posit that coumarin-(RFDF)4 containing peptide sequences are ideal candidates for pH-sensing bioelectronic materials.

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Metal-Metal Cooperative Bond Activation by Heterobimetallic Alkyl, Aryl, and Acetylide PtII/CuI Complexes

10.26434/chemrxiv.11742687 ◽

2020 ◽

Author(s):

Shubham Deolka ◽

Orestes Rivada Wheelaghan ◽

Sandra Aristizábal ◽

Robert Fayzullin ◽

Shrinwantu Pal ◽

...

Keyword(s):

Alkyl Group ◽

Bond Activation ◽

Bond Cleavage ◽

Terminal Alkyne ◽

Alkyl Aryl ◽

Metal Metal ◽

The Stability ◽

Selective Formation ◽

Organoplatinum Compounds

We report selective formation of heterobimetallic PtII/CuI complexes that demonstrate how facile bond activation processes can be achieved by altering reactivity of common organoplatinum compounds through their interaction with another metal center. The interaction of the Cu center with Pt center and with a Pt-bound alkyl group increases the stability of PtMe2 towards undesired rollover cyclometalation. The presence of the CuI center also enables facile transmetalation from electron-deficient tetraarylborate [B(ArF)4]- anion and mild C-H bond cleavage of a terminal alkyne, which was not observed in the absence of an electrophilic Cu center. The DFT study indicates that the role of Cu center acts as a binding site for alkyne substrate, while activating its terminal C-H bond.

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LANDSLIDE RISK MANAGEMENT IN THE COASTAL ZONE OF THE KUIBYSHEV RESERVOIR DUE THE DESIGN OF HIGH-SPEED LINE "MOSCOW-KAZAN"

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.31519/conferencearticle_5b1b9403c99983.72529271 ◽

2017 ◽

Author(s):

Nikolai Petrov ◽

Inna Nikonorova ◽

Vladimir Mashin ◽

...

Keyword(s):

High Speed ◽

Computational Models ◽

Stable State ◽

Landslide Risk ◽

Kuibyshev Reservoir ◽

Stepped Surface ◽

The Stability ◽

Landslide Slope ◽

The Village

High-speed railway "Moscow-Kazan" by the draft crosses the Volga (Kuibyshev reservoir) in Chuvashia region 500 m below the village of New Kushnikovo. The crossing plot is a right-bank landslide slope with a stepped surface. Its height is 80 m; the slope steepness -15-16o. The authors should assess the risk of landslides and recommend anti-landslide measures to ensure the safety of the future bridge. For this landslide factors have been analyzed, slope stability assessment has been performed and recommendations have been suggested. The role of the following factors have been analyzed: 1) hydrologic - erosion and abrasion reservoir and runoff role; 2) lithologyc (the presence of Urzhum and Northern Dvina horizons of plastically deformable rocks, displacement areas); 3) hydrogeological (the role of perched, ground and interstratal water); 4) geomorphological (presence of the elemental composition of sliding systems and their structure in the relief); 5) exogeodynamic (cycles and stages of landslide systems development, mechanisms and relationship between landslide tiers of different generations and blocks contained in tiers). As a result 6-7 computational models at each of the three engineering-geological sections were made. The stability was evaluated by the method “of the leaning slope”. It is proved that the slope is in a very stable state and requires the following measures: 1) unloading (truncation) of active heads blocks of landslide tiers) and the edge of the plateau, 2) regulation of the surface and groundwater flow, 3) concrete dam, if necessary.

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Short-Term Ultramicronized Palmitoylethanolamide Therapy in Patients with Myasthenia Gravis: a Pilot Study to Possible Future Implications of Treatment

CNS & Neurological Disorders - Drug Targets ◽

10.2174/1871527318666190131121827 ◽

2019 ◽

Vol 18 (3) ◽

pp. 232-238 ◽

Cited By ~ 5

Author(s):

Emanuela Onesti ◽

Vittorio Frasca ◽

Marco Ceccanti ◽

Giorgio Tartaglia ◽

Maria Cristina Gori ◽

...

Keyword(s):

Pilot Study ◽

Myasthenia Gravis ◽

Repetitive Nerve Stimulation ◽

Beneficial Effects ◽

Antibody Titers ◽

The Stability ◽

Ultramicronized Palmitoylethanolamide ◽

Open Pilot

Background: The cannabinoid system may be involved in the humoral mechanisms at the neuromuscular junction. Ultramicronized-palmitoylethanolamide (μm-PEA) has recently been shown to reduce the desensitization of Acetylcholine (ACh)-evoked currents in denervated patients modifying the stability of ACh receptor (AChR) function. Objective: To analyze the possible beneficial effects of μm-PEA in patients with myasthenia gravis (MG) on muscular fatigue and neurophysiological changes. Method: The duration of this open pilot study, which included an intra-individual control, was three weeks. Each patient was assigned to a 1-week treatment period with μm-PEA 600 mg twice a day. A neurophysiological examination based on repetitive nerve stimulation (RNS) of the masseteric and the axillary nerves was performed, and the quantitative MG (QMG) score was calculated in 22 MG patients every week in a three-week follow-up period. AChR antibody titer was investigated to analyze a possible immunomodulatory effect of PEA in MG patients. Results: PEA had a significant effect on the QMG score (p=0.03418) and on RNS of the masseteric nerve (p=0.01763), thus indicating that PEA reduces the level of disability and decremental muscle response. Antibody titers did not change significantly after treatment. Conclusion: According to our observations, μm-PEA as an add-on therapy could improve muscular response to fatigue in MG. The possible modulation of AChR currents as a means of eliciting a direct effect from PEA on the conformation of ACh receptors should be investigated. The co-role of cytokines also warrants an analysis. Given the rapidity and reversibility of the response, we suppose that PEA acts directly on AChR, though further studies are needed to confirm this hypothesis.

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Binding of calcium and lead ions to carboxystarch prepared by action of nitrogen dioxide on native starch and its 2,3-dialdehyde derivatives

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19861340 ◽

1986 ◽

Vol 51 (6) ◽

pp. 1340-1351 ◽

Cited By ~ 3

Author(s):

Rudolf Kohn ◽

Karol Tihlárik

Keyword(s):

Nitrogen Dioxide ◽

Alkaline Medium ◽

Binding Capacity ◽

Lead Ions ◽

Carbonyl Groups ◽

Weakly Alkaline ◽

Exchange Cations ◽

Counter Ions ◽

The Stability ◽

Derivatives Of

The binding of calcium and lead ions to carboxy derivatives of starch prepared by allowing nitrogen dioxide to act on native maize starch (procedure A) and on starch 2,3-dialdehyde derivatives of degrees of oxidation DO(d.a.) ≥ 0.94 (procedure B) was studied. The carboxy group content of the samples in the H+ form was 4.6 - 12.1 mmol g-1. The effect of alkaline medium on the stability of the carboxy derivatives and on their ability to bind and exchange cations was examined. The Ca2+ → 2K+ exchange was evaluated in terms of the decrease in the electrostatic free enthalpy Δ(Gel/N)KCa, determined by alkalimetric potentiometric titrations, and the binding of Pb2+ ions was evaluated in terms of the activity of the Pb2+ counter-ions determined in suspensions of Pb salts of the carboxy derivatives by means of an ion specific electrode. The IR and CD spectra revealed that the carboxystarch preparations obtained by procedure A contained, in addition to free carboxy groups, a considerable amount of carbonyl groups. During the conversion of the latter groups to the former, even in a weakly alkaline medium, the carboxy derivatives undergo an appreciable degradation and lose, to a great extent, their ability to bind and exchange cations. Procedure B, on the other hand, leads to highly selective starch and amylose carboxy derivatives, exhibiting a small amount of carbonyl groups and featuring a relative stability towards alkaline medium; their binding capacity is as high as 12 milliequivalents of cations per g of sample.

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On the Structure of Lead(II) Complexes in Aqueous Solutions. I. Trinuclear Clusters

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19950527 ◽

1995 ◽

Vol 60 (4) ◽

pp. 527-536 ◽

Cited By ~ 10

Author(s):

Martin Breza ◽

Alena Manová

Keyword(s):

Quantum Chemistry ◽

Aqueous Solutions ◽

Electronic Structures ◽

Mndo Method ◽

Model Systems ◽

Trinuclear Clusters ◽

The Stability ◽

Semiempirical Mndo

Using semiempirical MNDO method of quantum chemistry the optimal geometries and corresponding electronic structures of [Pb3(OH)n]6-n model systems as well as of their hydrated [Pb3(OH)n(H2O)8-n]6-n analogues (n = 4, 5) are investigated. The most stable trinuclear lead(II) complexes present in aqueous solutions correspond to cyclo-(μ3-OH)(μ2-OH)3Pb32+, Pb(μ-OH)2Pb(μ-OH)2Pb2+, cyclo-(μ3-OH)2(μ2-OH)3Pb3+, Pb(OH)(μ-OH)2Pb(μ-OH)Pb(OH)+ and Pb(OH)(μ-OH)2Pb(μ-OH)2Pb+ systems. The key role of OH bridges (by vanishing direct Pb-Pb bonds) on the stability of individual isomers is discussed.

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