Structures and photophysical properties of 3,4-diaryl-1H-pyrrol-2,5-diimines and 2,3-diarylmaleimides

Structural features of 3,4-diaryl-1H-pyrrol-2,5-diimines and their derivatives have been studied by molecular spectroscopy techniques, single-crystal X-ray diffraction, and DFT calculations. According to the theoretical calculations, the diimino tautomeric form of 3,4-diaryl-1H-pyrrol-2,5-diimines is more stable in solution than the imino-enamino form. We also found that the structurally related 2,3 exist in the solid state in the dimeric diketo form. 3,4-Diary1-1H-pyrrol-2,5-diimines and 2,3-diarylmaleimides exhibit fluorescence in the blue region of the visible spectrum. The fluorescence spectra have large Stokes shifts. Aryl substituents at the 3,4-positions of 1H-pyrrol-2,5-diimine do not significantly affect fluorescence properties. The insertion of donor substituents into 2,3diarylmaleimides leads to bathochromic shift of emission bands with hyperchromic effect. (C) 2017 Elsevier B.V. All rights reserved

C,N-chelated diaminocarbene platinum(II) complexes derived from 3,4-diaryl-1H-pyrrol-2,5-diimines and cis-dichlorobis(isonitrile)platinum(II):Synthesis, cytotoxicity, and catalytic activity in hydrosilylation reactions

The reaction of 3,4-diaryl-1H-pyrrol-2,5-diimines with cis-dichlorobis(isonitrile)platinum(II) affords the C,N-chelated diaminocarbene platinum(II) complexes, which have been fully characterized including molecular spectroscopy, single crystal X-ray diffraction and DFT calculations. The obtained platinum(II) complexes are effective catalysts for the hydrosilylation of alkynes and alkenes. Thus, the reaction of phenylacetylene with triethoxysilane leads to the formation of α- and β-(E)-vinylsilanes, generating TON's in the range of 103 to 104 and TOF's in the range of 102 to 103 h−1. Also, the cross-linked silicones, possessing the luminescence properties, were obtained by the hydrosilylation reaction of vinyl- and hydride-containing polysiloxanes. Additionally, the efficiency of diaminocarbene platinum(II) complexes against CH1/PA-1, SW480, and A549 cancer cell lines has been demonstrated by in vitro cytotoxicity studies.peerReviewe

Examining the influence of corporate website favorability on corporate image and corporate reputation: findings from fsQCA

This study uses the attribution and signaling theory perspective to scrutinize the key impacts of the determinants of corporate website favorability. In addition, this paper examines the main influences of satisfaction and attractiveness on corporate image and reputation, observes the role that the demographics of consumers (gender and age) play in such relationships, and proposes a research model along with research tenets. To examine these tenets, the conceptual framework was empirically evaluated through the perceptions of 563 consumers toward the financial setting in Russia (563). This study employs complexity theory, which integrates the principle of equifinality. To examine the data, this research employs fuzzy set qualitative comparative analysis (fsQCA) and confirmatory factor analysis (CFA). Additionally, this study makes a managerial contribution to the understanding of marketing and communication managers and website designers regarding the associations among corporate website favorability, its antecedents, and its consequences

5,5,5-Trichloropent-3-en-one as a Precursor of 1,3-Bi-centered Electrophile in Reactions with Arenes in Brønsted Superacid CF3SO3H. Synthesis of 3-Methyl-1-trichloromethylindenes

Reactions of 5,5,5-trichloropent-3-en-2-one Cl3CCH=CHC(=O)Me with arenes in Brønsted superacid CF3SO3H at room temperature for 2 h–5 days afford 3-methyl-1-trichloromethylindenes, a novel class of indene derivatives. The key reactive intermediate, O-protonated form of starting compound Cl3CCH=CHC(=OH+)Me, has been studied experimentally by NMR in CF3SO3H and theoretically by DFT calculations. The reaction proceeds through initial hydroarylation of the carbon-carbon double bond of starting CCl3-enone, followed by cyclization onto the O-protonated carbonyl group, leading to target indenes. In general, 5,5,5-trichloropent-3-en-2-one in CF3SO3H acts as a 1,3-bi-centered electrophile

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

Trichloromethyl-substituted enones (1-aryl-4,4,4-trichlorobut-2-en-1-ones, ArCOCH=CHCCl3, CCl3-enones) undergo intramolecular transformation into 3-trichloromethylindan-1-ones (CCl3-indanones) in Brønsted superacid CF3SO3H (triflic acid, TfOH) at 80 °C within 2–10 h in yields up to 92%. Protonation of the carbonyl oxygen of the starting CCl3-enones by TfOH affords the key reactive intermediates, the O-protonated forms ArC(=OH+)CH=CHCCl3, which are then cyclized into the target CCl3-indanones. These cations have been studied experimentally by means of NMR spectroscopy in TfOH and theoretically by DFT calculations. Under the same superacidic conditions in TfOH, CCl3-hydroxy ketones (1-aryl-4,4,4-trichloro-3-hydroxybutan-1-ones; ArCOCH2CH(OH)CCl3) undergo dehydration to the corresponding CCl3-enones, which are further cyclized into CCl3-indanones. The yields of CCl3-indanones starting from CCl3-hydroxy ketones are up to 86% in TfOH at 80 °C within 3–18 h

Mechanism and Regioselectivity of the Electrochemical Reduction in Polychlorobiphenyls (PCBs): Kinetic Analysis for the Successive Reduction of Chlorines from Dichlorobiphenyls

The regioselective electrochemical reduction of three different dichlorobiphenyls is analyzed using quantum chemical calculations and convolution potential sweep voltammetry. The heterogeneous rate constants of C–Cl bond reductions of each of the dichlorobiphenyls are estimated. The mechanism of the electrochemical reduction is confirmed by estimating the intrinsic barrier from the experimental data on transfer coefficients as well as theoretical calculations involving bond length and potential energy diagrams. The reductions follow the Marcus–Hush quadratic activation driving force relation barring the meta-Cl of the 3,4-dichlorobiphenyl which obeys Butler–Volmer kinetics. The first electron transfer step is rapid in comparison with the bond-breaking, implying the stepwise reduction for all the dichlorobiphenyls studied here. High performance liquid chromotagraphy analysis of the products of the bulk electrolysis confirms the order of the reduction in dichlorobiphenyls viz. the ease of reduction follows the order ortho-Cl > para-Cl > meta-Cl

Transformations of Conjugated Enynones in the Superacid CF₃SO₃H. Synthesis of Butadienyl Triflates, Indanones, and Indenes

Conjugated 1,5-diarylpent-2-en-4-yn-1-ones add the superacid CF₃SO₃H to the acetylenic bond with formation of the corresponding butadienyl triflates. Under superacidic reaction conditions, these triflates are transformed into indanone or indene derivatives depending on which substituents on the aromatic ring are conjugated with the butadiene fragment. In a less acidic system (10% vol pyridine in CF₃SO₃H) only the formation of butadienyl triflates takes place. Cationic reaction intermediates were studied by means of NMR and DFT calculations

Acid-Promoted Reaction of Trifluoromethylated Allyl Alcohols with Arenes. Stereoselective Synthesis of CF₃‑Alkenes and CF₃‑Indanes

Reaction of 4-aryl-1,1,1-trifluorobut-3-en-2-ols [CF₃-allyl alcohols, ArCHCHCH­(OH)­CF₃] with arenes under activation with anhydrous FeCl₃ or FSO₃H was studied. We found that the transformation led to trifluoromethylated alkenes [Ar­(Ar′)­CHCHCHCF₃] or 1-trifluoromethylated indanes (CF₃-indanes). The formation of these two types of reaction products strongly depends on the nucleophilicity of the starting arene and the electrophilicity of cationic intermediates generated from CF₃-allyl alcohols under reaction conditions. Benzene, anisole, veratrole, and <i>ortho-</i>xylene lead exclusively to CF₃-alkenes with an <i>E-</i>configuration. More π-donating polymethylated arenes (pseudocumene, mesitylene) afford only CF₃-indanes with a predominantly <i>cis-</i>orientation of substituents at positions 1 and 3 of the indane ring. <i>Meta-</i> and <i>para-</i>xylenes show an intermediate behavior; they may form both CF₃-alkenes and/or CF₃-indanes. The mechanisms of the investigated transformations are discussed