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Archive for April 27, 2016

Sci. Rep., 2016, 6, 24270

D.A. Markelov, V.V. Matveev, P. Ingman, M.N. Nikolaeva, A.V. Penkova, E. Lahderanta, N.I. Boiko, V.I. Chizhik

“Unexpected Temperature Behavior of Polyethylene Glycol Spacers in Copolymer Dendrimers in Chloroform”

Sci. Rep., 2016, 6, 24270
DOI:10.1038/srep24270

We have studied copolymer dendrimer structure: carbosilane dendrimers with terminal phenylbenzoate mesogenic groups attached by poly(ethylene) glycol (PEG) spacers. In this system PEG spacers are additional tuning to usual copolymer structure: dendrimer with terminal mesogenic groups. The dendrimer macromolecules were investigated in a dilute chloroform solution by 1H NMR methods (spectra and relaxations). It was found that the PEG layer in G = 5 generations dendrimer is “frozen” at high temperatures (above 260 K), but it unexpectedly becomes “unfrozen” at temperatures below 250 K (i.e., melting when cooling). The transition between these two states occurs within a small temperature range (~10 K). Such a behavior is not observed for smaller dendrimer generations (G = 1 and 3). This effect is likely related to the low critical solution temperature (LCST) of PEG and is caused by dendrimer conformations, in which the PEG group concentration in the layer increases with growing G. We suppose that the unusual behavior of PEG fragments in dendrimers will be interesting for practical applications such as nanocontainers or nanoreactors.

Beilstein J. Org. Chem., 2015, 11, 373-384

N.A. Danilkina, P.S. Vlasov, S.M. Vodianik, A.A. Kruchinin, Y.G. Vlasov, I.A. Balova

“Synthesis and chemosensing properties of cinnoline-containing poly(arylene ethynylene)s”

Beilstein J. Org. Chem., 2015, 11, 373-384
DOI:10.3762/bjoc.11.43

Novel poly(arylene ethynylene)s comprising a cinnoline core were prepared in high yields via a three-step methodology. A Richter-type cyclization of 2-ethynyl- and 2-(buta-1,3-diynyl)aryltriazenes was used for cinnoline ring formation, followed by a Sonogashira coupling for the introduction of trimethylsilylethynyl moieties and a sila-Sonogashira coupling as the polycondensation technique. The fluorescence of the cinnoline-containing polymers in THF was highly sensitive to quenching by Pd2+ ions.

Open Doors Day, Institute of Chemistry


At an Open Day of Institute of Chemistry (SPBU) Michael Vovk has presented a lecture-excursion for high school students about modern NMR methods and equipments.

Rus. J. Coord. Chem., 2016, 42, 178-186

E.A. Katlenok, A.A. Zolotarev, A.Yu. Ivanov, S.N. Smirnov, R.I. Baichurin, K.P. Balashev

“Complexes of Ir(III) and Pt(II) with Cyclometallated 2-Phenylbenzothiazole and Chelating Diethyldithiocarbamate and O-Ethyldithiocarbonate Ions: Structures and Optical and Electrochemical Properties”

Rus. J. Coord. Chem., 2016, 42, 178-186
DOI:10.1134/S1070328416030039

It is shown by X-ray diffraction analysis, IR spectroscopy, and 1Н, 13С{1H}, and 195Pt NMR spectroscopy that the Pt(II) and octahedral Ir(III) complexes with metallated 2-phenylbenzothiazole and chelating diethyldithiocarbamate and O-ethyldithiocarbonate ions have the square and cis-C,C structure, respectively. The highest occupied and lowest unoccupied molecular orbitals of the complexes determining their long-wavelength absorption, phosphorescence, and one-electron oxidation and reduction are assigned to those predominantly localized on the mixed p(S)/d(M) and π* orbitals of the metallated ligand. The cathodic shift of the oxidation voltammogram and the bathochromic phosphorescence shift of the Pt(II) complex with the О-ethyldithiocarbonate ion are attributed to the enhanced donor–acceptor interaction of the donor S atoms of the ligand with Pt(II). The structural data are deposited with the Cambridge Crystallographic Data Centre (CIF files CCDC nos. 1058768 (Ia) and 1058767 (IIb)).

MR_laboratories_in_Russia_2015-2016


“List of MR laboratories in Russia 2015-2016”

Russ J Org Chem., 2016, 52, 421-428

A.Ya. Bespalov, T.L. Gorchakova, A.Yu. Ivanov, M.A. Kuznetsov, L.M. Kuznetsova, A.S. Pan’kova, L.I. Prokopenko, A.F. Khlebnikov

“On the Possibility for Synthesizing Dihydrotriazolothiadiazoles by Condensation of 4-Amino-2,4-dihydro-3H-1,2,4-triazole-3-thiones with Aromatic Aldehydes”

Russ J Org Chem., 2016, 52, 421-428
DOI:10.1134/S1070428016030210

Regardless of the conditions, the condensation of 4-amino-2,4-dihydro-3H-1,2,4-triazole-3-thiones with aromatic aldehydes afforded the corresponding hydrazones as the only product. Both initial amines and resulting hydrazones exist as the thione rather than thiol tautomer. In no case bicyclic 5,6-dihydro[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles that are isomeric to the hydrazones were detected. DFT quantum chemical calculations at the B3LYP/6-31+g(d,p) level of theory with full geometry optimization showed that the hydrazone structure in methanol and DMF is more stable than the bicyclic isomer by 19–23 kcal/mol, which completely excluded the possibility for such cyclization. The thione tautomer of the hydrazones is more stable than the thiol structure by 11–13 kcal/mol.

Asian J. Org. Chem., 2016, 5, 389-398

M.V. Sorokina, A.S. Pankova, M.A. Kuznetsov

“Oxidative Aminoaziridination of 2-Vinylfuran Derivatives as an Approach to Hexa-2,5-diene-1,4-dione Monohydrazones”

Asian J. Org. Chem., 2016, 5, 389-398
DOI:10.1002/ajoc.201500460

The oxidative addition of N-aminophthalimide to substituted 2-vinylfurans provides monophthaloylhydrazones of (2Z)-hexa-2,5-diene-1,4-dione derivatives instead of 2-furylaziridines by proceeding through an aziridination of the endocyclic furan C=C bond followed by a regio- and stereoselective rearrangement of the bicyclic intermediate. The formation of stable aziridines can then occur through the aziridination of the (E)-C=C bond of these phthaloylhydrazones. Detailed structure elucidations and mechanistic considerations are provided.

Tetrahedron Lett., 57, 641-644

S. Miltsov, V. Karavan, A. Misharev, J. Alonso-Chamarro, M. Puyol

“Boron trifluoride–methanol complex. Mild and powerful reagent for deprotection of acetylated amines. Scope and selectivity”

Tetrahedron Lett., 2016, 57, 641-644
DOI:10.1016/j.tetlet.2015.12.087

A boron trifluoride–methanol complex demonstrated remarkable deprotection selectivity against commonly used amino-protecting groups in the deacetylation of acetanilides and high sensitivity to the steric hindrance of substrates. The scope and limitations of the reaction were explored.

Dalton Trans., 44, 17756-17766

A. Antonov, A. Pozharskii, V. Ozeranskii, A. Filarowski, K. Suponitsky, P. Tolstoy
“Ring Lithiation of 1,8-Bis(dimethylamino)naphthalene: Another Side of the ‘Proton Sponge Coin”

Dalton Trans., 2015, 44, 17756-17766
DOI:10.1039/C5DT02482J

31_2015

It has been found that 1,8-bis(dimethylamino)naphthalene (DMAN), unlike N,N-dimethylaniline, undergoes ring metallation in the n-BuLi–TMEDA–Et2O system with a low selectivity and in poor total yields. The situation is significantly improved in the t-BuLi–TMEDA–n-hexane system when 3- and 4-lithium derivatives become the only reaction products obtained in good yields. The formation of 3-Li-DMAN is especially desired since no method of direct meta-functionalization of DMAN is known to date. The relative stability and structure of DMAN lithium derivatives have been examined with the help of X-ray and multinuclear NMR measurements as well as DFT calculations.

Spectrum without substance


Not enough substance for NMR? Just add scheme of structure or candy.