Design,synthesis, photochromism and electrochemistry of a novel material with pendant photochromic units

In the present work, the synthesis, photochromism and electrochemistry of a novel material 1, 1-(4-[3,4-bis(2,5-dimethyl-3-thienyl)cyclopent-3-en-1-yl]phenyl)-2,5-di-2-thienyl-1H-pyrrole, with pendant dithienylethene (DTE) photochromic units are described. It should be noted that the system 1 can be reversibly and efficiently switched between open (1o) and closed (1c) states by light in both solution and in the solid poly(methyl methacrylate) matrix. It is also noteworthy that the two isomers (1o and 1c) of this novel system 1 can be smoothly polymerized on ITO by electrochemical means. Surprisingly, the DTE unit in 1 does not retain its photochemical switching properties after immobilization onto ITO. The morphology of the polymer film was investigated by AFM analysis. Furthermore, it was found that the polymer exhibited remarkable electrochromic features that can be switched from green in the neutral state to violet state under applied external potentials without disturbing the photochromic units.     

Relative Group Cohomology and The Orbit Category

Let G be a finite group and ? be a family of subgroups of G closed under conjugation and taking subgroups. We consider the question whether there exists a periodic relative ?-projective resolution for ? when ? is the family of all subgroups H ≤ G with rk H ≤ rkG ? 1. We answer this question negatively by calculating the relative group cohomology ?H*(G, 𝔽₂) where G = ?/2 × ?/2 and ? is the family of cyclic subgroups of G. To do this calculation we first observe that the relative group cohomology ?H*(G, M) can be calculated using the ext-groups over the orbit category of G restricted to the family ?. In second part of the paper, we discuss the construction of a spectral sequence that converges to the cohomology of a group G and whose horizontal line at E ₂ page is isomorphic to the relative group cohomology of G.     

Atomistic Engineering of Chemiluminogens: Synthesis,Properties and Polymerization of 2,3-Dihydro-Pyrrolo[3,4-d]Pyridazine-1,4-Dione Scaffolds

Two chemiluminescent compounds containing 2,5-di(thien-2-yl)pyrrole and pyridazine units, namely 5,7-di(thiophen-2-yl)-2,3-dihydro-1H-pyrrolo[3,4-d]pyridazine-1,4(6H)-dione (5) and 6-phenyl-5,7-di(thiophen-2-yl)-2,3-dihydro-1H-pyrrolo[3,4-d]pyridazine-1,4(6H)-dione (6), were successfully synthesized and electrochemically polymerized. The compounds have chemiluminescent properties and glow in the presence of hydrogen peroxide in basic medium. The intensity of the glow can be increased dramatically by using Fe³⁺ ions, hemin (1.0 ppm) or blood samples (1.0 ppm) as catalyst. The compounds 5 and 6 have one well-defined irreversible oxidation peak at 1.08 V and 1.33 V vs Ag/AgCl, respectively. Electrochemical polymerization of both 5 and 6 were carried out successfully by repeating potential scanning in the presence of BF₃. Et2O in an electrolyte solution of 0.1 M LiClO₄ dissolved in acetonitrile. The electronic band gaps (E_g) of the polymers P5 and P6 were found to be 2.02 eV and 2.16 eV, respectively. On the other hand, the corresponding polymers are electroactive and exhibited electrochromic features.

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Graphical Abstract ?

     

Hydrogen Bonded Supramolecular Network from a Mixed Valence Cobalt System: Synthesis and Crystal Structure of [Co(H2O)6][Co(pydc)2(en)]2·14H2O

Abstract  

The [Co(H₂O)₆][Co(pydc)₂(en)]₂·14H₂O (1) compound (H₂pydc = Pyridine-2,3-dicarboxylic acid and en = ethylenediamine) was synthesized and characterized by elemental analysis, magnetic and spectroscopic measurements (UV–Vis and IR spectra) and single crystal X-ray diffraction technique. There are two coordination spheres with different charges inside this aqueous compound of ionic character. The cationic part is composed of Co(II) encircled by six aqua ligand. Whereas the anionic part contains two anions complex unit each with −1 charge and have Co(III) ions in the centre. As a result different coordination spheres have cobalt ions with different states. The crystallographic analysis revealed that 1 consists of both discrete one-cationic and two-anionic entities, [Co(H₂O)₆]²⁺ and [Co(pydc)₂(en)]₂⁻ and fourteen crystal water molecules. Two water molecules within the water cluster act as hydrogen-bonding acceptors, whereas one water molecule acts as a hydrogen-bonding donor to form a discrete water trimer. These water molecules have stabilized the crystal structure by strong hydrogen bonding interactions.     

Semi-empirical effective pair correlation parameters and correlation energies of BH,CH, NH,OH, HF,N2, and CH4

A set of approximations (EPCE-F2) is given for estimating the correlation energies of molecules. The approximations start from Sinanolu's pair correlations and his many-electron theory for ground states (MET). For application of this method, effective pair correlation energies must be known. In the present paper three sets of one-center effective pair correlation energies are obtained from the atomic pair correlation energies. A weighted average method is introduced for handling the non-transferable atomic correlation energies. For the corresponding two-center effective pair correlation energies several empirical expressions are given. Then using three sets of one-center effective pair correlation energies and for the two-center ones, the correlation energies of some diatomic hydrides, N₂ and CH₄ molecules are estimated. The results agree quite well with each other, with experimental values, and with those obtained by other methods.

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Zusammenfassung Ein Näherungsverfahren (EPCE-F2) zur Abschätzung der Korrelationsenergie von Molekülen wird angegeben. Die Näherungen gehen von Sinanoglus Paarkorrelation und seiner Mehrelektronentheorie für Grundzustände (MET) aus. Zur Anwendung dieser Methode müssen Effektive Paarkorrelationsenergien bekannt sein. In der vorliegenden Veröffentlichung werden drei Sätze von solchen effektiven Paarkorrelationsenergien für ein Zentrum aus atomaren Paarkorrelationsenergien gewonnen. Zur Behandlung der nichtübertragbaren atomaren Korrelationsenergien wird eine Methode mit gewichteten Mittelwerten angewendet. Für die entsprechenden effektiven Paarkorrelationsenergien für zwei Zentren werden verschiedene semiempirische Ausdrücke angegeben. Mit je drei Sätzen von Werten für die genannten Energiewerte für ein Zentrum oder zwei Zentren werden die Korrelationsenergien für einige zweiatomige Hydride sowie die Moleküle N₂ and CH₄ abgeschätzt. Die Ergebnisse stimmen gut untereinander und mit experimentellen Werten sowie mit Werten aus anderen Verfahren überein.

     

Full Lutz twist along the binding of an open book

Let T denote a binding component of an open book (S, f){(\Sigma, \phi)} compatible with a closed contact 3-manifold (M, ξ). We describe an explicit open book (S￠, f￠){(\Sigma', \phi')} compatible with (M, ζ), where ζ is the contact structure obtained from ξ by performing a full Lutz twist along T. Here, (S￠, f￠){(\Sigma', \phi')} is obtained from (S, f){(\Sigma, \phi)} by a local modification near the binding.     

Surfactant-induced healing of tough hydrogels formed via hydrophobic interactions

Different reversible molecular interactions have been used in the past few years to generate self-healing in synthetic hydrogels. However, self-healing hydrogels synthesized so far suffer from low mechanical strength which may limit their use in any stress-bearing applications. Here, we present a simple technique to heal mechanically strong polyacrylamide hydrogels formed via hydrophobic interactions between stearyl groups. A complete healing in the hydrogels was achieved by the treatment of the damaged areas with an aqueous solution of wormlike sodium dodecyl sulfate micelles. The micelles in the healing agent solubilize the hydrophobes in the cut surfaces, so that they easily find their partners in the other cut surface due to the hydrophobic interactions. Surfactant-induced healing produces high toughness (～1 MPa) gels withstanding 150 kPa of stress at a deformation ratio of 1,100 %. The healing technique developed here is generally applicable to the physical gels formed by hydrophobic associations.     

New Pt(0) Nanoparticles as Highly Active and Reusable Catalysts in the C1–C3 Alcohol Oxidation and the Room Temperature Dehydrocoupling of Dimethylamine-Borane (DMAB)

New Pt(0) nanoparticles were easily and reproducibly prepared by the simultaneous reduction method using 1-butylamine (BA) and tributylamine (TBA) for the first time as capturing ligands at room temperature. X-ray diffraction, X-ray photoelectron microscopy and transmission electron microscopy measurements verify the formation of well-dispersed Pt(0) nanoparticles [~3.63 and ~3.98 nm for catalysts prepared using BA (catalyst I) and TBA (catalyst II), respectively] on an activated carbon surface. The catalytic performances of these nanoparticles in terms of activity, isolability and reusability were investigated for both alcohol oxidation and the dehydrocoupling of dimethylamine-borane (DMAB). These nanoparticles were shown to be as active and reusable heterogeneous catalysts even at room temperature. The prepared catalysts can catalyze the dehydrogenation of DMAB with one of the highest known activities at room temperature and also C1–C3 alcohol oxidation with very high electrochemical activities.