Ethylenic Bond Research Articles

Influence of structural variations on electrical conductivity and solubility of 1-vinyl-3-alkylimidazole halogen ionic liquids

Several 1-vinyl-3-alkylimidazolium halogens [VRIM]X, which are functional materials with ethylenic bonds, were synthesized using the microwave-assisted synthesis method. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy were carried out to analyze the resultant structures. The electrochemical properties and solubility of [VRIM]Br were investigated and discussed in detail. The temperature dependence of pure [VRIM]Br over a wide temperature range of 298.15–323.15 K fitted the Arrhenius equation well. At certain low concentrations, the electrical conductivity of the [VRIM]Br solution significantly increased with increasing solution concentration. The electrical conductivities of the [VRIM]Br observed in water, methanol, and ethanol showed the trend σ water > σ methanol > σ ethanol. Conductometry showed that the critical micelle concentrations of the bromines in water, methanol, and ethanol were 6.8–6.9 × 10−6, 1.4–1.5 × 10−5, and 1.9–2.0×10−5 mol·L−1, respectively; these results indicate that [VRIM]Br is an excellent surfactant. The solubility of [VRIM]X in common solvents was determined at 293.15 K, and results indicated that a decrease in solubility could be observed with decreasing dielectric constant of the solvent, elongation of the alkyl chain of the cation, and increasing anion size. Solubility parameters were also determined according to the Hildebrand-Scoff equation.

Synthesis, structure and properties of two series of platinum(II) complexes containing methyleugenol or chelating methyleugenol and amine

Two series of platinum(II) complexes of the formula [PtCl2(Meug)(Amine)] (1–6, Meug: methyleugenol) and [PtCl(Meug-1H)(Amine)] (7–13, Meug-1H: deprotonated methyleugenol) were synthesized and characterized by elemental analyses, IR, 1H NMR, 13C NMR, NOESY and XRD spectra. In complexes 1–6 the methyleugenol ligand coordinates to Pt(II) through the ethylenic double bond of the allyl group, and the amine is in the trans-position in comparison to the ethylenic double bond. In complexes 7–13 the chelating methyleugenol ligand is bound to Pt(II) both through the ethylenic double bond of the allyl group and via an aromatic carbon. NOESY spectra and single-crystal X-ray diffraction of [PtCl(Meug-1H)(o-toluidine)] (14) indicate that in 7–14 the amines are in a cis-position with respect to the ethylenic double bond. [PtCl2(Meug)(Pyridine)] (4), [PtCl2(Meug)(Quinoline)] (5) and [PtCl(Meug-1H)(Quinoline)] (9) exhibit strong activities on human cancer cells KB with IC50 values of 3.7, 3.4 and 3.2μg/mL respectively.

Molecular rotors based on styryl dyes. Viscosity dependence of rotation of molecular fragments

Three donor-acceptor styryl dyes R-Het+-CH=CH-C6H4-NR′R″ClO4 − (Het is pyridyl) were synthesized. Their spectral-luminescence behavior allows their assignment to a class of molecular rotors. The influence of the viscosity, polarity, and temperature of the medium on their absorption and fluorescence properties was studied. A pronounced enhancement of dye fluorescence accompanied by a short-wavelength shift of the fluorescence maximum is observed with an increase in the viscosity of the medium and temperature decrease. The measurements of the fluorescence spectra of the dyes in the poly(methyl methacrylate) films at 293 and 77 K confirmed the effect of the medium viscosity on the rotation ability of molecular fragments upon photoexcitation. According to the quantum chemical calculations, in excited molecules of the styryl dyes in nonpolar solvents, molecular fragments rotate mainly about the central ethylene bond \((HC\underline \cdots CH)\). In polar solvents, the rotation barriers around the ordinary bonds of the ethylene fragment decrease.

Zwitterionic hydrogel thin films as antifouling surface layers of polyethersulfone ultrafiltration membranes anchored via reactive copolymer additive

The fabrication and properties of anti-fouling and hemocompatible polyethersulfone (PES) membranes having zwitterionic hydrogel thin films as surface layers were described in this paper. PES membranes containing a reactive block copolymer PES-b-PHEDMA as an additive were first prepared by traditional non-solvent induced phase separation process. The hydrogel thin films were then grafted from membrane surface by free radical cross-linking polymerization participated by reactive ethylenic bonds in the PES-b-PHEDMA additive. The analysis of attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the successful immobilization of zwitterionic hydrogel thin films on PES membrane surfaces. Due to the hydrophilic and low-fouling characteristics of zwitterionic surfaces, the hydrogel-modified PES membranes showed significantly improved anti-fouling ability. More importantly, the zwitterionic membranes exhibited excellent hemocompatibility and the hydrogel thin films showed good durability in long-term tests. This work provides us with a facile and versatile strategy of covalently anchoring hydrogel thin films onto polymer membranes to achieve excellent anti-fouling properties and hemocompatibility.

On the interplay between chirality and exciton coupling: a DFT calculation of the circular dichroism in π-stacked ethylene.

The chirality of stacked weakly interacting π-systems was interpreted in terms of Frenkel exciton states and the formation of excitonic circular dichroism (CD) bands was monitored for ethylene stacks of varying sizes. Convergence of CD bands with respect to the system size was observed for stacks involving around 10 molecules. By means of rotation around the C-C double bond in ethylene, chirality was induced in the monomeric system and which was shown to dominate the spectral responses, even for polymer aggregates. In helical assemblies of chiral entities, there will always be a mix of excitonic and monomeric contributions to the CD signal and it is demonstrated that the complex polarization propagator approach in combination with Density Functional Theory is a suitable method to address this situation.

A combined crossed molecular beams and ab initio investigation on the formation of vinylsulfidoboron (C₂H₃¹¹B³²S).

We exploited crossed molecular beams techniques and electronic structure calculations to provide compelling evidence that the vinylsulfidoboron molecule (C2H3(11)B(32)S) - the simplest member of hitherto elusive olefinic organo-sulfidoboron molecules (RBS) - can be formed via the gas phase reaction of boron monosulfide ((11)B(32)S) with ethylene (C2H4) under single collision conditions. The reaction mechanism follows indirect scattering dynamics via a barrierless addition of the boron monosulfide radical to the carbon-carbon double bond of ethylene. The initial reaction complex can either decompose to vinylsulfidoboron (C2H3(11)B(32)S) via the emission of a hydrogen atom from the sp(3) hybridized carbon atom, or isomerize via a 1,2-hydrogen shift prior to a hydrogen loss from the terminal carbon atom to form vinylsulfidoboron. Statistical (RRKM) calculations predict branching ratios of 8% and 92% for both pathways leading to vinylsulfidoboron, respectively. A comparison between the boron monosulfide ((11)B(32)S) plus ethylene and the boron monoxide ((11)BO) plus ethylene systems indicates that both reactions follow similar reaction mechanisms involving addition - elimination and addition - hydrogen migration - elimination pathways. Our experimental findings open up a novel pathway to access the previously poorly-characterized class of organo-sulfidoboron molecules via bimolecular gas phase reactions, which are difficult to form through 'classical' organic synthesis.

5''-Benzyl-idene-5-chloro-1',1''-dimethyl-4'-phenyl-dispiro-[indoline-3,2'-pyrrolidine-3',3''-piperidine]-2,4''-dione.

The title compound, C30H28ClN3O2, features two spiro links, one connecting the piperidine and pyrrolidine rings, and the other connecting the pyrrolidine ring and indole residue. The configuration about the ethene bond is E. The piperidine ring adopts a half-chair conformation where the C atom connected to the spiro-C atom lies 0.713 (3) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.086 Å). The pyrrolidine ring has an envelope conformation with the flap atom being the methyl­ene C atom. Centrosymmetric eight-membered {⋯HNCO}2 amide synthons feature in the crystal packing. These are consolidated into a three-dimensional architecture by phen­yl–pyrrolidine C—H⋯N and chloro­benzene–pyrrolidine-bound phenyl C—H⋯π inter­actions.

Synthesis and kinetic study of diacrylate and dimethacrylate

A recently developed successful approach to achieve the balanced properties involves the copolymerization of film forming monomers like acrylate and methacrylates with crosslinkable monomers. The crosslinker used in the copolymerization of acrylates are basically compound with at least two non-conjugated ethylenic double bonds in their molecule. The kinetics of esterification of multifunctional monomers were investigated using poly(propylene glycol) diacrylates. The effect of methyl group on reaction kinetics was investigated. The diacrylate / dimethacrylate based on polypropylene glycol (molecular weight 400) were synthesized by reacting with acrylic / methacrylic acid in presence of a catalyst. The decrease in acid value and the presence of prominent peak, –C = O stretching, at 1,731 cm−1 showed the formation of diacrylate and dimethacrylate. The value of rate constant for PPGDA at all temperatures were higher than that for PPGDA, indicating that the reactivity of PPG towards acrylic acid is more than methacrylic acid.

Theoretical Study of Topographical Features around the Conical Intersections of 9-(2-Cyclopenten-1-ylidene)-9H-fluorene

Ab initio molecular orbital calculations have been performed to examine the topographical features around the conical intersections (CIXs) for the photoisomerization of 9-(2-cyclopenten-1-ylidene)-9H-fluorene (CPF). The present study is motivated by the computational findings of the topographical features in the CIX region of a fluorene-based light-driven molecular motor with smooth rotation (denoted by M5-PCPF). CPF is a parent molecule of M5-PCPF but exhibits neither helicity nor unidirectionality. A stable geometry in S1 (S1-geometry) is located in the region where the ethylenic rotary axis is perpendicularly twisted, but the fluorene part wags little against the rotary axis, as is the case of M5-PCPF. However, the topographical features around the CIXs of CPF are different from those of M5-PCPF. The wagging motion of the fluorene stator to the negative direction from S1-geometry leads straight to a CIX which implements forward and backward rotations. On the other hand, only the wagging motion to the positive direction does not lead to a CIX, and additional geometrical deformations are needed. Depending on the directions of additional geometrical deformations, two CIXs, which play the roles of respective exit channels for forward and backward rotations, are located in the positive wagging region. The difference in the topographical features in the CIX region between CPF and M5-PCPF is ascribed to the effect of the pentamethylene chain. By virtue of much less computational labor of CPF as well as the electronic structures being similar to those of M5-PCPF, the intrinsic reaction coordinate was followed from the ethylenic ππ* state at the stable geometry in S0 into S1-geometry. Thereby, it was confirmed that a spectroscopically dark state due to the π(fluorene)π*(ethylene) excitation contributes less to the photochemical process of the ethylenic bond torsion, as is the case of M5-PCPF.

NMR structure of 2′-O-(2-methoxyethyl) modified and C5-methylated RNA dodecamer duplex

The solution-state structure of 2'-O-(2-methoxyethly) substituted dodecamer r(*CG*CGAA*U*U*CG*C)d(G), 2'-MOE RNA, with all cytosines and uracils methylated at the C5-position has been determined by NMR spectroscopy. The chemical modifications were used to improve the oligonucleotide's drug-like properties. The 2'-MOE group drives pseudorotational equilibrium of the ribofuranose moiety to the N-type conformation and supposedly results in structural preorganization leading to high affinity of a modified oligonucleotide towards its complementary biological target, improved pharmacokinetic and toxicological properties. The high melting temperature of the antiparallel duplex structure adopted by 2'-MOE RNA was explained through the formation of a stable A-form RNA consistent with effective base-pairing and stacking interactions. The comparison of the solution-state structure with the crystal structure of a non-methylated analogue shows an increase in the stacking at the base pair steps for the C5-methylated 2'-MOE RNA duplex. The MOE substituents adopt a well-defined structure in the minor groove with the predominant gauche conformations around the ethylene bond.

Design of crystal packings of styryl heterocycles and regularities of [2+2] photocycloaddition in their single crystals 8. Topochemical [2+2] autophotocycloaddition and back reaction in styryl dye of the benzothiazole series

New styryl dye of the 2-benzothiazole series was synthesized. The new dye contains two methoxy groups in the benzene ring and tosylate counterion. The [2+2] photocycloaddition (PCA) of the dye was studied in the polycrystalline film and in single crystal. Two modifications of the dye cocrystallizate with hydroquinone differed in the ratio of components were obtained, and their ability to enter PCA was studied. According to the X-ray diffraction data, molecular cations of the dye form stack packings either of syn-“head-to-tail” type or relatively isolated stacking dimers. In all cases, the ethylene bonds of the adjacent cations are brought together and antiparallel, favoring PCA to form the centrosymmetric rctt-isomer of 1,2,3,4-tetrasubstituted cyclobutane. In two cases, the PCA reaction proceeded as the “single crystal-to-single crystal” transformation. Hydrogen bonds in crystals including hydroquinone molecules strengthen the crystal packing retarding the PCA. The back photoreaction (retro-PCA) was detected: it occurs without single crystal decomposition and results in the accumulation of the initial styryl dye in crystal consisting of the cyclobutane derivative. This is the first example of such a transformation in single crystals.

Electronic Properties of π-Conjugated Nickel Bis(dithiolene) Network and Its Addition Reactivity with Ethylene

Density functional theory computations were performed to study the structure and electronic properties of the recently achieved two-dimensional nickel bis(dithiolene) single-layer sheet, as well as its cycloaddition activity with ethylene. The nickel bis(dithiolene) monolayer has a planar and porous network, and electrically acts as an indirect band gap semiconductor. Its lowest unoccupied state mainly distributes onto p orbitals of S atoms, which makes S atoms active to accept electrons from the occupied p orbitals of C═C bonds in ethylene. This is indeed confirmed by our computations, and the formation of the cis-interligand S,S′-adduct with an activation energy barrier of about 21 kcal/mol is energetically favored. When an extra electron is added, the addition product becomes destabilized and would dissociate into ethylene and nickel bis(dithiolene) anion. Therefore, with a controllable manner, the nickel bis(dithiolene) monolayer can bind and release ethylene molecules in neutral and reduction conditions, respectively. Because of its unique chemical reactivity, this newly achieved nickel bis(dithiolene) sheet can be potentially developed as an electrocatalyst in olefin separation and purification.

(2E)-1-(2,4-Dimethylquinolin-3-yl)-3-phenylprop-2-en-1-one

Two independent mol­ecules comprise the asymmetric unit of the title compound, C20H17NO, which differ in the orientation of the terminal phenyl ring with respect to the quinoline ring [the dihedral angles are 75.72 (11) and 84.53 (12)° for the two mol­ecules]. The conformation about each of the ethyl­ene bonds [1.329 (3) and 1.318 (3) Å] is E. The crystal structure features a combination of C—H⋯N, C—H⋯π and π–π contacts [inter-centroid between the phenyl ring and the quinoline benzene ring is 3.6024 (19) Å], generating a three-dimensional network.

Synthesis and characterization of Gd 0.1 Ce 0.9 O 1.95 nanopowder via an acetic–acrylicmethod

Abstract Nanocrystalline Ce0.9Gd0.1O1.95 (GDC) powders are successfully prepared by an acetic–acrylic method using acrylic acid, cerium acetate and gadolinium acetate as the starting materials. The polymeric precursors are characterized by means of TG/DTA, XRD and FT-IR, and the resultant powders are characterized by XRF, BET, SEM and particle size distribution (PSD) analysis. It is shown that the morphology of the oxide particles is dependent on the preparation conditions such as molar ratio of acrylic acid to metallic ions (L/M) and the sort of surfactant. High purity, single phase, homogeneous, nanocrystalline GDC powders with slight aggregation are obtained using ethylene glycol as surfactant, L/M=0.5 and heat treatment above 600 °C. The low application amount and high effect of acrylic acid is attributed to the co-operation of carboxyl group and ethylenic bond. The electrical conductivity of the sintered GDC pellet is 0.053 Scm−1 in air at 750 °C. The present work indicates that the acetic–acrylic method is a relatively green method without any NOx to synthesize high performance GDC powders.

Structure, energy, vibrational spectrum, and Bader's analysis of π⋯H hydrogen bonds and H−δ⋯H+δdihydrogen bonds

In this paper, the intermolecular structural study asserted by the vibrational analysis in the stretch frequencies of hydrogen bonds (π···H) and dihydrogen bonds (H(-δ)···H(+δ)) have definitively been revisited by means of calculations carried out by Density Functional Theory (DFT) and topological parameters derived from the classic treatise of the Quantum Theory of Atoms in Molecules (QTAIM). As a matter of fact the π···H hydrogen bond is formed between the hydrofluoric acid and the C≡C bond of the acetylene, but the QTAIM calculations revealed a distortion in this interaction due to the formation of the ternary complex C(2)H(2)···2(HF). Although the π bonds of ethylene (C(2)H(4)), propylene (C(2)H(3)(CH(3))), and t-butylene (C(2)H(2)(CH(3))(2)) are considered proton acceptors, two hydrogen-bond types--π···H and C···H--can be observed. Over and above the analysis of the π hydrogen bonds, theoretical arguments also were used to discuss the red-shifts in the stretch frequencies of the binary dihydrogen complexes formed by BeH(2)···HX with X = F, Cl, CN, and CCH. Although a vibrational blue-shift in the stretch frequency of the H-C bond of HCF(3) due to the formation of the BeH(2)···HCF(3) dihydrogen complex was obtained, unmistakable red-shifts were detected in LiH···HCF(3), MgH(2)···HCF(3), and NaH···HCF(3). Moreover, the alkali-halogen bonds were identified in relation to the formation of the trimolecular systems NaH···2(HCF(3)) and NaH···2(HCCl(3)). At last, theoretical calculations and QTAIM molecular integrations were used to study a novel class of dihydrogen-bonded complexes (mC(2)H(5)(+)···nMgH(2) with m = 1 or 2 and n = 1 or 2) based in the insight that MgH(2) can bind with the non-localized hydrogen H(+δ) of the ethyl cation (C(2)H(5)(+)). In an overview, QTAIM calculations were applied to evaluate the molecular topography, charge density, as well as to interpret the shifted frequencies either to red or blue caused by the formation of the hydrogen bonds and dihydrogen bonds.

Search for Novel Anti-tumor Agents from Ridaifens Using JFCR39, a Panel of Human Cancer Cell Lines

To overcome the heterogeneous nature of cancer, the search for potent anti-cancer drug candidates with new modes of action is essential. For that purpose, we prepared forty-eight Ridaifens (RIDs), a novel series of tamoxifen-derivatives. Then, we screened them, searching for novel candidates for a new class of anti-cancer drug using a panel of human cancer cell lines (JFCR39) and by a binding assay to estrogen receptor α (ERα). First, the growth inhibition of the forty-eight RIDs against JFCR39 was evaluated. Forty RIDs showed higher growth-inhibitory activity than that of tamoxifen. The structure-activity relationship (SAR) study revealed that the aminoalkoxyphenyl groups at the C-1 position and the common central ethylenic bond were important in retaining a high level of growth-inhibitory activity. Subsequently, the ERα binding activity of all the RIDs was measured by a competitive binding assay. The SAR study for ERα binding activity indicated that both the phenyl group and the ethyl group at the C-2 position in the ethylenic bond were essential. Based on the screenings, we identified RID-SB1 and RID-SB8, which demonstrated potent tumor growth inhibition but had completely lost ERα binding activity. Furthermore, the COMPARE analysis using JFCR39 suggested that RID-SB1 and RID-SB8 had different molecular modes of action compared to those of the current anti-cancer drugs including tamoxifen. These results indicate that RID-SB1 and RID-SB8 are interesting candidates for novel anti-cancer agents with unique modes of action.

The facile and efficient ultrasound-assisted synthesis of new quinoline-appended ferrocenyl chalcones and their properties

The facile and efficient synthesis of quinoline-appended ferrocenyl chalcones via the condensation of acetylferrocene (or substituted 2-methyl-3-acetylquinoline) with 2-chloro-3-formylquinoline (or ferrocenecarboxaldehyde) in ethanol under basic conditions by the ultrasonic method is reported and compared to the results of synthesis achieved through conventional methods. Two derivatives were investigated crystallographically which confirmed the E-conformation about the CC ethylene bond in each case. Redox chemistry of the new chalcones was investigated by cyclic voltammetry which showed quasi-reversible one-electron redox processed with potentials correlated with electron-withdrawing substituents. The compounds showed promising antimicrobial properties, with derivatives 3a and 6a showing the maximum activity against bacterial and fungal strains, respectively.

1,2-Bis{4-[1-(anthracen-9-ylmeth-yl)-1H-1,2,3-triazol-4-yl]phen-yl}-1,2-bis-[4,5-bis-(methyl-sulfan-yl)-1,3-dithiol-2-yl-idene]ethane.

The title mol­ecule, C58H44N6S8, has point symmetry 2 (in the Schönfliess notation C 2). The related crystallographic twofold axis bis­ects the central ethane bond while it is parallel to the monoclinic unique axis of the unit cell. The dithiole=C—C=dithiole torsion angle is 103.7 (4)° and the triazole–anthracene moieties adopt a pincer-like conformation. The crystal structure features C—H⋯S and C—H⋯N contacts. The distance between the stacked anthracene fragments [centroid—centroid separations of 3.6871 (19) Å, off-set by 1.516 (3) Å and mean anthracene plane-plane separations of 3.361 (2) Å], which are parallel to (101) and (-101), indicates inter­molecular anthracene–anthracene π–π contacts. One of the terminal methyl­sulfanyl groups was modelled as being disordered with two refined orientations that converged to occupancies of 0.809 (5) and 0.191 (5).

Quantum Chemical Study of the Initial Step of Ozone Addition to the Double Bond of Ethylene

The mechanisms of the initial step in chemical reaction between ozone and ethylene were studied by multireference perturbation theory methods (MRMP2, CASPT2, NEVPT2, and CIPT2) and density functional theory (OPW91, OPBE, and OTPSS functionals). Two possible reaction channels were considered: concerted addition through the symmetric transition state (Criegee mechanism) and stepwise addition by the biradical mechanism (DeMore mechanism). Predicted structures of intermediates and transition states, the energies of elementary steps, and activation barriers were reported. For the rate-determining steps of both mechanisms, the full geometry optimization of stationary points was performed at the CASPT2/cc-pVDZ theory level, and the potential energy surface profiles were constructed at the MRMP2/cc-pVTZ, NEVPT2/cc-pVDZ, and CIPT2/cc-pVDZ theory levels. The rate constants and their ratio for reaction channels calculated for both mechanisms demonstrate that the Criegee mechanism is predominant for this reaction. These results are also in agreement with the experimental data and previous computational results. The structure of DeMore prereactive complex is reported here for the first time at the CCSD(T)/cc-pVTZ and CASPT2/cc-pVDZ levels. Relative stability of the complexes and activation energies were refined by single-point energy calculations at the CCSD(T)-F12/VTZ-F12 level. The IR shifts of ozone bands due to formation of complexes are presented and discussed.

Gas-Phase Synthesis of the Silaisocyanoethylene Molecule (C2H3NSi)

The gas-phase reaction between the silicon nitride radical (SiN) and the prototypical olefin--ethylene--is investigated experimentally and theoretically for the first time. Silicon nitride (SiN) and the cyano radical (CN) are isoelectronic; however, their chemical reactivities and structures are drastically different from each other. Through the use of the cross molecular beam technique, we were able to study the notoriously refractory silicon nitride radical in reaction with ethylene under single-collision conditions. We investigated the similarities and also the distinct differences with the cyano radical-ethylene system. We find that the silicon nitride radical bonds by the nitrogen atom to the double bond of ethylene; in comparison, the cyano radical adds via its carbon atom. The silicon nitride addition is barrierless, forming a long-lived SiNCH(2)CH(2) collision complex, which is also able to isomerize via a hydrogen shift to the SiNCHCH(3) intermediate. Both isomers can emit a hydrogen atom via tight transition states to form the silaisocyanoethylene (SiNC(2)H(3)) molecule in an overall exoergic reaction. This presents the very first experiment in which the silaisocyanoethylene molecule--a member of the silaisocyanide family--has been formed via a directed synthesis under gas-phase single-collision conditions. In comparison with the isoelectronic cyano-ethylene system, the cyanoethylene (C(2)H(3)CN) isomer is formed. Therefore, the replacement of a single carbon atom by an isovalent silicon atom, i.e. shifting from the cyano (CN) to the silicon nitride (SiN) radical, has a dramatic influence not only on the reactivity with ethylene (carbon atom versus nitrogen atom addition) but also on the final reaction products. In the reactions of ethylene with silicon nitride and the cyano radical, the silaisonitrile over the silanitrile and the nitrile over the isonitrile reaction products are favored, respectively. This reaction provides rare experimental data for investigating the chemistry of bimolecular reactions of silicon nitride diatomics in chemical vapor deposition techniques and interstellar environments.