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The behavior of 4-thienyl substituted pyrimidine ligands (L 1–3 ) has been studied for the series of their reactions with various salts of 3d metals (Co, Zn, Ni, Cu) and platinoids (Pt, Pd). In particular, mononuclear Co(OTf) 2 (L 1–3 ) 2 (H 2 O) 2 (MeCN) 2 ( 1 ), binuclear Co 2 (Piv) 2 (L 1–3 ) 4 ( 2a , b ), Cu 2 (Piv) 2 (L 1–3 ) 2 ( 5a , b ), heterometallic polynuclear Li 2 Co 2 (Piv) 6 (L 1–3 ) 2 ( 4 ) and chelate [(L 1 )Pd(OAc)] 2 ( 6 ) complexes have been obtained. The structures of all complexes have been established by X-ray diffraction. Also magnetic properties of coordination compounds 1 , 2 , 4 and 5 have been studied in details. In particular, mononuclear Co(II) complexes 1 and 4 proved to exhibit paramagnetism with large positive zero-field splitting parameters. Dinuclear Co(II) complexes 2a , b show weak antiferromagnetic interactions. Dinuclear Cu(II) complexes 5a , b demonstrate strong antiferromagnetic superexchange interactions via four carboxylate bridges. The systems 2a , b and 5a , b are isolated as exchange coupled dimers. [ABSTRACT FROM AUTHOR]

Combination of the Suzuki cross-coupling and nucleophilic aromatic substitution of hydrogen ( S N H ) reactions proved to be a convenient method for the synthesis of C(4) and/or C(5) mono(thienyl) and di(thienyl) substituted pyrimidines from commercially available 5-bromopyrimidine. All new pyrimidines were found to be active in micromolar concentrations in vitro against H 37 Rv, avium , terrae , rifampicin and isoniazid-resistance strains of Mycobacterium tuberculosis . The data for acute in vivo toxicity in mice have been obtained for these compounds which appear to be promising antitubercular agents. [ABSTRACT FROM AUTHOR]

Abstract: Six novel donor–π–acceptor organic dyes bearing a pyrimidine as the anchoring group have been obtained in good yields by combination of the microwave-assisted Suzuki cross-coupling and nucleophilic aromatic substitution of hydrogen reactions. Their absorption, photoluminescence and electrochemical properties were fully investigated in detail. The infrared spectra of dyes adsorbed on TiO2 indicate the formation of coordinate bonds between the pyrimidine ring of dyes and the Lewis acid sites (exposed Ti n+ cations) of the TiO2 surface. This work demonstrates that the pyrimidine rings of dye sensitizers that form a coordinate bond with the Lewis acid site of a TiO2 surface are promising candidates as the electron-withdrawing anchoring group. The data from quantum calculations show that all of the dyes are potentially good photosensitizers for dye-sensitized solar cells. [Copyright &y& Elsevier]

Abstract: 5-Bromopyrimidine reacts with 2,2′-bithiophene, [2,2′:5′,2″]terthiophene and 2-phenylthiophene in the presence of a palladium catalyst to give 5-(het)aryl substituted pyrimidines due to the palladium-catalyzed aryl–aryl C–C coupling. However 5-bromo-4-(het)aryl-pyrimidines have been prepared from the same starting materials through the SN H-reaction catalyzed by a Lewis acid. Conditions for both types of reactions were optimized. All components of the reaction mixtures, including by-products, have been elucidated by gas–liquid chromatography/mass-spectrometry. Evidence for the structure of 4- and 5-bithiophenyl-substituted pyrimidines has first been obtained by means of X-ray crystallography analysis. Molecular orbital calculations (TDDFT), as well as the redox and optical measurements for all new compounds have also been performed. [Copyright &y& Elsevier]

Abstract: It has been shown that combination of the Suzuki–Miyaura cross-coupling and nucleophilic aromatic substitution of hydrogen is a versatile method for the synthesis of 4-(thiophen-2-yl)-, 5-(thiophen-2-yl)-, and 4,5-di(thiophen-2-yl) substituted pyrimidines from the commercially available 5-bromopyrimidine. The (AE)- and (AO)-reactions of 5-bromopyrimidine with thiophene and 2-bromothiophene have been studied by gas–liquid chromatography/mass-spectrometry. The structures of intermediate σH-adducts, as well as thiophene-(thiophenyl)pyrimidine and bithiophene-(thiophenyl)pyrimidine dyads have first been established by X-ray crystallography analysis. [Copyright &y& Elsevier]

A series of D–π–A–π–D type dyes based on pyrimidines, bearing thiophene linkers, have been studied as sensing fluorophores. Fluorescence studies have demonstrated that the emission of all derivatives is sensitive to the presence of 2,4,6-trinitrotoluene (TNT) and other nitroaromatic compounds (NACs), in their acetonitrile solutions. The detection limits of fluorophores to NACs proved to be in the range from 10 −4 to 10 −6 mol/L. The time-resolved fluorescence measurements and theoretical investigation into the quenching mechanism in the presence of fluorophore has been performed. The two types of sensor prototypes for handheld sniffer «Nitroscan» (Plant «Promautomatika», Ekaterinburg, Russia) on the basis of non-woven dry wipe and spunlace non-woven fabric with various quantities of the most sensitive fluorophore have been fabricated. The reusable, reversible and sensitive response of the designed prototypes to NACs enables one to qualify these compounds as promising fluorescent sensory materials for detection of NACs. [ABSTRACT FROM AUTHOR]

A number of D–π–A type dyes on the basis of new 2 H -[1,2,3]triazolo[4,5- e ][1,2,4]triazolo[1,5- a ]pyrimidines, bearing various electron-donating carbazole and triphenylamine fragments, have been studied as sensing fluorophores. Fluorescence studies have demonstrated that emission spectra of these compounds in acetonitrile are sensitive to the presence of nitroaromatic explosives, such as 2,4-dinitroanisole (DNAN), picric acid (PA), styphnic acid (SA), 1,3,5-triethoxy-2,4,6-trinitrobenzene (TETNB), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT) and nitrobenzene (NB). Detection limits of fluorophores for DNAN, PA, SA, TETNB, DNT and TNT proved to be in the range from 4.82×10 −1 to 2.96×10 −3 mol/L, 2.10×10 −3 to 5.98×10 −5 mol/L, 1.26×10 −1 to 2.02×10 −4 mol/L, 1.58×10 −1 to 1.62×10 −3 mol/L, 1.26×10 −1 to 5.61×10 −4 mol/L and 9.01×10 −2 to 2.77×10 −3 mol/L, respectively. Selective fluorescence quenching response, including a sharp color change under UV irradiation (especially for PA, SA and DNT), makes these compounds promising fluorescence chemosensors for nitroaromatic explosives. [ABSTRACT FROM AUTHOR]