Synthesis and structural investigation of 4,4′-dimethyl-[3,3′-bi(1,2,5-oxadiazole)] 5,5′-dioxide

The oxidation of hexane-2,3,4,5-tetraone tetraoxime with dinitrogen tetroxide was studied in different solvents. The primary furoxan ring closure was found to occur involving either two central or two terminal oxime groups to form 4,7-dimethyl[1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide and the previously unknown 4,4′-dimethyl-[3,3′-bi(1,2,5-oxadiazole)] 5,5′-dioxide. The structure of the latter compound was established by X-ray diffraction.     

Preparation,crystal structure and luminescence of lanthanide coordination polymers with 2,2′-dimethyl-4,4′-bipyridine-N,N′-dioxide

Four coordination polymers of the bidentate ligand 2,2′-dimethyl-4,4′-bipyridine-N,N′-dioxide (L), [La(L)(NO₃)₃(H₂O)] _n (1), {[Gd₂(L)₃(NO₃)₆]·6H₂O} _n (2), {[Sm(L)₂(H₂O)₄]·3ClO₄·2L·4H₂O} _n (3) and {[Nd(L)₂(H₂O)₄]·3ClO₄·2L·4H₂O} _n (4) have been synthesized by the diffusing solvent mixture method. Results of X-ray diffraction analysis reveal that 1, with a Ln/L stoichiometry of 1:1, displays a rare 3-D three-fold interpenetrating diamondoid framework, while 2 has a Ln/L stoichiometry of 1:1.5 and exhibits a polycatenane network with a {8²,10} topology and large channels accommodated by water. Complexes 3 and 4, with Ln/L stoichiometry of 1:2, have 3-D two-fold interpenetrating diamondoid structures and large voids. Nonlinear optical property of 2 and luminescence of 3 were also investigated.     

Pulse and γ-radiolysis studies on aqueous solution of 1,1′-dimethyl-2-selenourea

One-electron oxidation of 1,1′-dimethyl-2-selenourea (DMSeU) by hydroxyl radicals, one-electron-specific oxidants, was studied using pulse radiolysis technique in aqueous solution. Hydroxyl (OH) radicals and one-electron oxidants, N₃, X₂⁻ (X=Cl, Br, and I) react with DMSeU to form a transient having an absorption spectrum with λ_max at 430 nm. By following the absorbance at 430 nm as a function of solute concentration and in analogy with similar sulfur and selenium compounds, this transient is assigned to dimer radical cation. The dimer radical cations of DMSeU react with oxygen with bimolecular rate constant of 1.0±0.3×10⁸ M⁻¹ s⁻¹. Steady-state γ-radiolysis studies on aqueous solution of DMSeU under hydroxyl radical-induced oxidation condition indicated formation of elemental selenium as one of the by-products, which has been stabilized by the addition of poly vinyl alcohol (PVA), and characterized by dynamic light scattering technique.     

Copper (I) and silver (I) complexes of dithiomalonamide,NN′-dimethyl- and NN′-diphenyl-dithiomalonamide.

Some copper (I) and silver (I) complexes with dithiomalonamide (Hdtma), NN′-dimethyl-(HMe₂dtma) and NN′-diphenyl-dithiomalonamide (HPh₂dtma) were prepared: Cu(Hdtma)X (X² = Cl, Br, I(H₂O), ClO₄); Cu(HL)₂X (HMe₂dtma: X = Cl, Br, I, ClO₄; HPh₂dtma: X = Cl, Br, I); Ag(HL)X (Hdtma: X = Cl; HMe₂dtma: X = Br, ClO₄, BF₄; HPh₂dtma: X = Br, I); Ag₂(HL)₃X₂ (Hdtma: X = ClO₄, BF₄; HMe₂dtma: X = Cl; HPh₂-dtma: X = Cl, ClO₄); Ag₂(HMe₂dtma)I₂ and Ag₃(Hdtma)₂Br₃. Molar conductivities in DMF show that the complexes behave: M₂(HL)₃(ClO₄)₂ as 1:2 electrolytes, M(HL) (ClO₄ of BF₄) as 1:1 electrolytes; those of the halides Cu(HL)X and Cu(HL)₂X, are almost equal and intermediate between values for non-electrolytes and 1:1 electrolites. Infrared spectra indicate an S,N-coordination for all the complexes: ν(MN) bands in the region of 400–500 cm⁻¹ and ν(MS) bands in the region of 300–400 cm⁻¹ (for Hdtma), 300–320 cm⁻¹ (for HMe₂dtma) and 260–280 cm⁻¹ (for HPh₂dtma) are observed. No ν(MX) bands were identified in the halide complexes indicating that a mental—halide coordination, if present in the solid complexes, should be very weak.     

Nickel(II) complex containing 5,5′-dimethyl-2,2′-bipyridine: Crystal structure and luminescent properties

[Ni(5,5′-dmbipy)₂Cl₂]·3H₂O (1) complex was obtained from the reaction of NiCl₂·6H₂O with 5,5′-dimethyl-2,2′-bipyridine (5,5′-dmbipy) in a mixture of CH₃OH/CH₃CN. This complex was characterized by elemental analysis, IR, UV-Vis and luminescence spectroscopy, and its structure was determined by the single-crystal diffraction method. The Ni atom has a distorted octahedral coordination by four N atoms from two 5,5′-dmbipy ligands and two Cl^– anions.     

Re-examination of 7,7′-dimethyl-7-germanorbornadiene photocleavage in solution and in organic glasses

Dimethylgermylene and its Ge=Ge doubly bonded dimer, tetramethyldigermene, have been characterized directly in solution by 308-nm laser flash photolysis in n-hexane solution, as well as 254-nm photolysis in hydrocarbon glasses at t = 77 K. An absorption band maximum of λ _max ≈ 430 nm and molar absorption coefficient of ε ≈ 2,700 M⁻¹ cm⁻¹ have been shown to be attributable to low-temperature glasses, while the absorption band maximum of λ _max ≈ 480 nm and molar absorption coefficient of ε ≈ 2,400 M⁻¹ cm⁻¹ have been shown to be related to dimethylgermylene in n-hexane solution. The molar absorption coefficient of tetramethyldigermene (λ _max ≈ 380 nm) was determined to be ε ≈ 84,000 M⁻¹ cm⁻¹. The germylene is formed via (formal) cheletropic photocycloreversion of 7,7′-dimethylgerma-1,4,5,6-tetraphenyl-2,3-benzo-norbornadiene. Tetramethyldigermene and 1,2,3,4-tetraphenylnaphthalene in the triplet state were formed, together with dimethylgermylene. We attempted to explain the various contradictory interpretations of experimental data existing in the literature on this reaction.     

Crystal and Molecular Structure of Bi-1,1′-(3,3-dimethyl-3,4-dihydroisoquinoline)

Bi-1,1-(3,3-dimethyl-3,4-dihydroisoquinoline) (I) was synthesized. Its crystal structure was determined by X-ray diffraction analysis. Compound I crystallizes as isomer that is intermediate between the syn- and anti-forms with the angle of rotation between the bicyclic fragments equal to 90.1°. The N(1)=C(1) bond length is 1.276(4) ± 0.003 Å.     

Synthesis of 1′-substituted 4′,4′-dimethyl-6′-methoxy-4′H-spiro[cyclohexane-1,3′-isoquinolines]

The reaction of 1-(4-methoxyphenyl)-1-(1-methylcyclohexyl)ethanol with nitriles in concentrated sulfuric acid afforded 1′-substituted 6′-methoxy-4′,4′-dimethyl-4′H-spiro[cyclohexane-1,3′-isoquinolines] as a result of consecutive Wagner-Meerwein rearrangement and Ritter reaction.     

Cadmium(II) complexes containing 2,2′-dimethyl-4,4′-bithiazole ligand: synthesis,characterization, and crystal structure

Mononuclear and coordination polymer compounds of 2,2′-dimethyl-4,4′-bithiazole (dm4bt) ligand have been prepared by metallation of dm4bt with Cd(NO₃)₂ · 4H₂O and CdCl₂ · H₂O. The compounds were characterized by IR, ¹H NMR, UV–Vis spectroscopy, and X-ray crystallography. The structural study of [Cd(dm4bt)₂(NO₃)₂] · H₂O (1) shows that the complex is a monomeric seven-coordinate (CdN₄O₃) cadmium(II)-bithiazole system with two bidentate dm4bt and mono and bidentate nitrates. The structure of [Cd(dm4bt)Cl₂] _n (2) is a distorted octahedral environment around the cadmium(II) (CdN₂Cl₄) forming a 1-D coordination polymer as a result of bridging by two chlorides and 2-D structure from π–π stacking interactions.     

Crystallographic and computational study of the structure of copper(II) 2,2′-bis(2-oxidobenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl

The reaction of M(OAc)₂ with 2,2′-bis(2-hydroxybenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl (H₂L1) allows the synthesis of 2,2′-bis(2-oxidobenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl complexes of Cu(II) (CuL1), Co(II) (CoL1) and Ni(II) (NiL1) that were characterized by elemental analysis, FTIR spectroscopy and for CuL1 also by X-ray crystallography verifying a tetradentate binding mode of L1 via an (ONNO) motif of the two phenolic oxygen atoms and two azomethine nitrogen atoms. Recrystallization from a solvent mixture of dichloromethane and methanol promotes the formation of methanol adducts. Different binding modes of the methanol–complex were investigated using density functional theory calculations and binding energies, and thermodynamic data of the interaction are reported. The results show that the favored interaction occurs when the methanol molecule acts as a Lewis acid weakly binding via an O–H···O hydrogen bridge to a phenoxide moiety leading to an elongation of the respective M–O bond.

     

A complex based on a decorated Keggin-type cluster from Cu(II) and 4,4′-dimethyl-2,2′-bipyridine: synthesis,structure and proton conductivity

A proton-conductive complex based on decorated Keggin-type cluster, {[Cu(dmbipy)(H₂O)₃]₂[SiW₁₂O₄₀]}·7H₂O (where dmbipy is 4,4′-dimethyl-2,2′-bipyridine) (1), was synthesized by reaction of CuSiW₁₂O₄₀·nH₂O and dmbipy at room temperature. The product was characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis at 293 K revealed that 1 crystallized in the monoclinic space group C2/c and has a 3-D supramolecular network with 1-D hydrophilic channels constructed by a decorated Keggin-type cluster, [Cu(dmbipy)(H₂O)₃]₂SiW₁₂O₄₀, and solvent water molecules via hydrogen-bonding interactions. Thermogravimetric analysis suggests that 1 has high-thermal stability and good water binding in 1-D hydrophilic channels from 20 to 100 °C. Compound 1 exhibits good proton conductivities (over 10^?3 S cm^?1) at 100 °C in the relative humidity range 35–98%.     

Two New Organic Supramolecular Complexes Based on 2,3,6,7-Tetrahydroxyl-9,10-dimethyl-9,10-dihydro-9,10-ethanoanthracene and 4,4′-Bipyridine or 4,4′-Bipyridinylethane

Two new organic supramolecular cocrystal complexes C18H18O4·C10H8N2(I) and C18H18O4·C12H10N2(II)(C18H18O4 = 2,3,6,7-tetrahydroxyl-9,10-dimethyl-9,10-dihydro-9,10-ethanoanthracene(LH4), C10H8N2 = 4,4'-bipyridine(bpy) and C12H10N2 = 4,4'-bipyridinylethane(bpe)) have been obtained by mixing LH4 with corresponding bpy or bpe ligand. The two complexes have been determined by X-ray crystal structure analysis, elemental analysis and IR analysis. Compound I crystallizes in the orthorhombic Pnma with a = 9.7078(4), b = 22.4974(10), c = 20.6272(9) V = 4505.0(3)3, Mr = 454.51, Dc. = 1.340 g·cm-3, μ = 0.09 mm-1, F(000) = 1920, Z = 8, R = 0.0503 and wR = 0.1360. Compound II crystallizes in monoclinic C2/c with a = 29.944(6), b = 9.820(2), c = 22.643(5) , V = 5048.4(18)3, Mr = 480.54, Dc. = 1.265 g cm–3, μ = 0.084 mm–1, F(000) = 2032, Z = 8, R = 0.0548 and wR = 0.1600. X-ray single-crystal structure analysis shows that two-dimensional(2D) layer supramolecular structures are formed through hydrogen bonds and π-π interactions in the two complexes. IR analysis also indicates that there are only associated hydroxyl groups in the two complexes.     

Chemiluminescence in oriented systems: chemiluminescence of 10,10′-dimethyl-9,9′-biacridinium nitrate in micellar media

A comparative study was made of the chemiluminescence of 10,10′-dimethyl-9,9′-biacridinium nitrate during its reactions with alkali and hydrogen peroxide in micellar and isotropic media. In the former medium the quantum efficiency increased markedly, but most importantly it was possible to detect for the first time light emission from the primary excited product which has always been prohibited in this reaction owing to unrestricted energy transfer in isotropic media.     

Poly[(3,3′-dimethyl-1,1′-biphenyl-4,4′-diyl)ethynediyl(2,5-dioctyl-1,4-phenylene)ethynediyl] and a related copolymer – new blue EL polymers

Electroluminescence (EL) properties of a new poly(aryleneethynylene) and a related copolymer were studied. They are poly[(3,3′-dimethyl-1,1′-biphenyl-4,4′-diyl)ethynediyl(2,5-dioctyl-1,4-phenylene)ethynediyl] (PPEBE) and related copolymer (PPEBE-co-mP) containing 20 mole % of 1,3-phenylene units. Both polymers are blue-light emitters; the former was found to perform better than the latter when the light-emitting diode (LED) device had the configuration of ITO/PEDOT/polymer/Li:Al. The device constructed with the former polymer exhibited the external quantum efficiency of 0.05 and the maximum brightness higher than 400 cd/m² with its EL spectrum showing maxima at λ = 445 and 472 nm. The performance of the device constructed with the copolymer was about one fifth of the device fabricated with the homopolymer.     

Synthesis,structure, and physico-chemical properties of 3-methyl and 3,3-dimethyl derivatives of l-(4′,4′-dimethyl-2′,6′-dioxocyclohex-1′-yl)-3,4-dihydroisoquinoline

3,3-Dimethyl- and 3-methyl-1-(4,4-dimethyl-2,6-dioxocyclohex-1-yl)-3,4-dihydroisoquinolines have been synthesized. Crystal and molecular structures of the 3,3-dimethyl derivative have been determined. In the crystalline state this compound exists as a tautomeric form where a hydrogen atom is located at the N atom of the dihydroisoquinoline fragment of the molecule. The tautomeric equilibrium does not shift noticeably in solutions, as shown by IR, UV, and NMR spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 331–336, February, 1993.     

Bis(4,4′-dimethyl-2,2′-bipyridine)ruthenium(II) Complexes Containing 2-Arylimidazo-phenanthroline: Syntheses, Characterization and Third-order Nonlinear Optical Properties

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Synthesis,characterization, and crystal structure determination of two mercury(II) dimer complexes with 4,7-diphenyl-1,10-phenanthroline, 5,5′-dimethyl-2,2′-bipyridine and bromide

Mercury(II) complexes, {[Hg(Ph₂phen)(μ-Br)]₂Br₂} · CH₃CN (1) and {[Hg(dmbpy)(µ-Br)]₂Br₂}(2) (where Ph₂phen is 4,7-diphenyl-1,10-phenanthroline and dmbpy is 5,5′-dimethyl-2,2′-bipyridine), were synthesized from reaction of HgBr₂ with Ph₂phen and dmbpy in CH₃CN and CH₃OH. Both complexes were thoroughly characterized by elemental analysis, infrared, ¹H and ¹³C NMR spectroscopy and single-crystal X-ray diffraction. Complexes 1 and 2 crystallize in the space group P2₁/n of the monoclinic and P 1 of the triclinic systems and contain four and one molecules per unit cell, respectively. The unit cell dimensions for 1 are: a = 20.422(4) Å, b = 11.384(2) Å, c = 20.665(4) Å, and β = 109.94(3)° and for 2 are: a = 8.7470(17) Å, b = 8.8328(18) Å, c = 9.4950(19) Å and α = 75.47(3)°, β = 82.21(3)°, γ = 85.56(3)°. According to X-ray structure determination both complexes are five coordinate with three bromides and one bidentate ligand; one bromide is set at a semi-bridging position.