Photochromic dihetarylethenes

The structures of two hetarylethene photochromes,viz., 1,2-bis(2-ethyl-5-ethylsulfonylthien-3-yl)perfluorocyclopentene and 1,2-bis[5-(benzoxazol-2-yl)-2-methylthien-3-yl]perfluorocyclopentene, were established by X-ray diffraction analysis. The conformational parameters of the title compounds are considered. The cyclopentene ring in the former compound is planar and this ring in the latter compound adopts an envelope conformation. There are no overall conjugated systems in the molecules under study. In both structures, the dihetaryl fragments are rotated with respect to the perfluorocyclopentene fragments by ∼55°. The thiophene and benzoxazole rings in 1,2-bis[5-(benzoxazol-2-yl)-2-methylthien-3-yl]perfluorocyclopentene are coplanar. For Part 3, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 74–77, January, 2000.     

Spectral,luminescent, and photophysical properties of dipyrrolylbenzenes

Dipyrroles with a phenylene bridge, 1,4-bis(pyrrol-2-yl)benzene, 4-(1-vinylpyrrol-2-yl)-1-(pyrrol-2-yl)benzene, and 1,4-bis(1-vinylpyrrol-2-yl)benzene, show intense room-temperature fluorescence in solutions. Analysis of electronic absorption spectra, fluorescence spectra, and results of B3LYP, TD B3LYP, and CIS quantum chemical calculations showed that the introduction of a bulky substituent in position 1 of the pyrrole ring makes the ground-state structures of dipyrrolylbenzenes less planar. Excited-state geometries of all molecules relax to more planar conformations. An increase in the probability of nonradiative transitions has little effect on the quantum yields of fluorescence (Φ_f) of dipyrrolylbenzenes. Even for 1,4-bis(1-vinylpyrrol-2-yl)benzene, where the pyrrole rings deviate from the benzene ring plane by 44°, the fluorescence efficiency remains high enough (Φ_f = 0.7). Substitution at nitrogen atoms has little effect on positions of fluorescence band maxima. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1433–1438, July, 2008.     

Photochromic dihetarylethenes. 18. New approach to the synthesis of dithienothiophene and preparation of its photochromic derivative

A new approach to the synthesis of dithienothiophene was developed, and 1,2-bis(2,6-dimethyldithieno[3,2-b;2",3"-d]thiophen-3-yl)hexafluorocyclopent-1-ene was prepared. The latter compound is the first representative of photochromic dihetarylethenes with the fused tricyclic fragments linked through the perfluorocyclene bridge.     

Synthesis of 1,2-bis(1-boraadamant-2-yl)ethane derivatives. Crystal structure of the racemic form

Condensation of triallylborane with octa-1,7-diyne followed by treatment of the reaction mixture with methanol afforded a mixture of stereoisomeric 1,4-bis(3-methoxy-3-bora-bicyclo[3.3.1]non-6-en-7-yl)butanes (1a,b). Hydroboration of the latter with a solution of BH₃ in THF yielded the tetrahydrofuran complex of 1,2-bis(1-boraadamant-2-yl)ethane (2) as a mixture of diastereomers. Pure racemate (2a) was obtained by crystallization from the reaction mixture and it was converted into the pyridine complex of 1,2-bis(1-boraadamant-2-yl)ethane (3). The structure of the latter was established by X-ray diffraction analysis. Complex2a was converted into the corresponding racemic 1,2-bis(1-hydroxyadamant-2-yl)ethane (4a) by the carbonylation-oxidation reaction. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 501–505, March, 2000.     

Photochromic dihetarylethenes. 10. Photochromic 1,2-bis[2-(benzothiazol-2-yl)-3-thienyl]- and 1,2-bis[2-(benzothiazol-2-yl)benzothiophen-3-yl]ethenes

Dithienylethenes containing the thiophene rings with benzothiazolyl substituents in position 2 were synthesized. 1,2-Bis[2-(benzothiazol-2-yl)benzothiophen-3-yl]hexafluorocyclopentene and 1,2-bis[2,5-di(benzothiazol-2-yl)-3-thienyl]hexafluorocyclopentene possess photochromic properties. The open forms of 1,2-bis(2-benzothiazolylhetaryl)ethenes fluoresce, but introduction of the benzothiazole rings into dihetarylethenes significantly lowers the fatigue resistance of photochromes and favors thermal reversibility.     

Synthesis,Structure and Photoluminescence of Cocrystal of Bis[2-(benz(oxa/imida)zol-2-yl)phenolato-к~2N,O]zinc(Ⅱ) Being Site Occupancy Disorder with a Heteroatom Ratio of NH to O(0.408/0.592)

1 INTRODUCTION Neutral zinc(II) complexes, being monomeric structure with tetrahedral geometries, have shown excellent photoluminescent properties[1, 2], and some of them also have excellent electroluminescent properties[3 ～ 5]. Therefore, neutral organic Zn(II) complexes have been used as both photoluminescent materials and electroluminescent emitters in organic diodes. For example, bis(2-(benzimidazol-2-yl)phe- nolate)zinc shows excellent performance in photolu- minescence[6], and bis…     

Two-step α-ureidoalkylation of ureas with 4,5-dihydroxyimidazolidin-2-ones

Two-step α-ureidoalkylation of ureas with various 4,5-dihydroxyimidazolidin-2-ones gave novel 1,3-dialkyl-4,5-bis(3-alkylureido)-, 1,3-dialkyl-4,5-bis[3-(2-pyrimidyl)ureido]-, or 1,3-dialkyl-4,5-bis(3,3-dialkylureido)imidazolidin-2-ones and ensembles of three imidazolidine rings. The structure of 4,5-bis(2-oxoimidazolidin-1-yl)imidazolidin-2-one was confirmed by X-ray diffraction data. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 140–145, January, 2007.     

Photochromic dihetarylethenes. 6. Photochromic derivatives of thieno[3,2-b]thiophene

1,2-Bis{5-(2-benzothiazolyl)-2-methyl-6-trifluoromethylthieno[3,2-b]thiophen-3-yl}hexafluorocyclopentene possessing high fatigue resistance was synthesized for the first time. Its photochromic and fluorescence properties were studied. The structure of its cyclic form was established by X-ray diffraction analysis.     

Oxidative Recyclization of 4,6,7-Trichloro-5-hydroxy-2-(2-pyrimidylamino)-2,3-dihydrobenzo[b]furan

When 4,6,7-trichloro-5-hydroxy-2-(2-pyrimidylamino)- 2,3-dihydrobenzo[b]furan reacted with phenyliodoso diacetate, an unexpected oxidative recyclization was observed to give 3-(3,5,6-trichloro-1,4-benzoquinon-2-yl)imidazo[1,2-a]pyrimidine. 2-[N-2-(3,5,6-Trichloro-1,4-benzoquinon-2-yl)ethenylamino]pyrimidine is the intermediate product in the conversion.     

1,2-Bis(dimethylamino)-3,4,5-triphenyl-3,4,5-triphospha-1,2-diborolan und 1,2-Bis(dimethylamino)-3,4,5,6-tetra-tbutyl-3,4,5,6-tetraphospha-1,2-diborin: Synthese und Struktur sowie Berechnungen zur Molekülstruktur

1,2-Bis(dimethylamino)-3,4,5-triphenyl-3,4,5-triphospha-1,2-diborolane and 1,2-Bis(dimethylamino)-3,4,5,6-tetra-tbutyl-3,4,5,6-tetraphospha-1,2-diborine: Synthesis and Structure as well as Calculations on the Molecular Structure The diphosphides K₂[(C₆H₅)P? (C₆H₅)P? P(C₆H₅)], 4 or K₂[(tBuP)? (tBuP)₂? P(tBu)], 5 , react with (ClBNMe₂)₂ to form the binary 5-membered ring system 1,2-bis(dimethylamino)-3,4,5-triphenyl-3,4,5-triphospha-1,2-diborolane (C₆H₅P)₃(BNMe₂)₂, 2a , and the 6-membered ring system 1,2-bis(dimethylamino)-3,4,5,6-tetra-tbutyl-3,4,5,6-tetraphospha-1,2-diborine, (tBuP)₄(BNMe₂)₂, 3a , respectively. 2a and 3a could be obtained in a pure form and characterized NMR spectroscopically and by X-ray structure analyses. The two ring systems are folded; 2a exists in the ?envelope”?- 3a in the ?boat”?-conformation. Ab initio computations for 3,4,5-triphospha-1,2-diborolane M5 show that the global minimum is characterized by one B? P double bond. The parent compound geometry M6 is characterized by transannular bonding in the PH? BH? BH? PH moiety which differs in character from those in the four- and five-membered rings (BH)₂(PH)₂ and (BH)₂(PH)₃ M5 d , respectively. Explicit calculation of the influence of amino substituents on boron improved agreement of the bond length between computed and X-ray data.     

Photochromic dihetarylethenes

1,2-Bis[2-methyl-5-(benzoxazol-2-yl)thien-3-yl]hexafluorocyclopentene was synthesized, and its photochronic properties were studied For Part 2, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1011–1014, May, 1999.     

Photochromic Dihetarylethylenes. 21. Synthesis and Photochemical Properties of 1,2-Bis{5-(2-benzothiazolyl)-2-ethylthieno-[2,3-<Emphasis Type="Italic">b</Emphasis>]thiophen-3-yl}Hexafluorocyclopentene

1,2-Bis{5-(2-benzothiazolyl)-2-ethylthieno[2,3-b]thiophen-3-yl}hexafluorocyclopentene has been synthesized for the first time. It was shown that, unlike analogous derivatives of thieno[3,2-b]thiophene, on irradiation with UV light (λ = 313 nm) it did not display photochromic properties, but undergoes an irreversible photoconversion which is accompanied by the display of intense fluorescence. This raises the prospect of using this compound for creating an irreversible photoluminescent recording medium.Dedicated to V. I. Minkin on his 70th birthday.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 360–364, March, 2005.For Part 20 see [1].     

Synthesis and crystal structures of three new complexes derived from 3-(pyridin-3′-yl)-5-(pyridin-2′′-yl)-1,2,4-triazole

Three new coordination complexes, [Cd₂(ppt)₂(cpba)]?·?(H₂O)₂ (1), [Zn(ppt)₂]?·?(H₂O) (2), and [Zn(MoO₄)(Hppt)] (3) (H₂cpba: 3-(2′-carboxy-phenoxy)-benzoic acid; Hppt: 3-(pyridin-3′-yl)-5-(pyridin-2′′-yl)-1,2,4-triazole), were synthesized under hydrothermal conditions. Their structures have been determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric analyses. X-ray diffraction analyses revealed that Cd(II) ions are linked by ppt^? to form a ladder-shaped structure along the a-axis and further displays a 2-D supramolecular architecture with cpba^2? along the c-axis. In 2, each Zn(ppt)₂ fragment is linked by the nitrogen of pyridin-3′-yl from the neighboring Zn(ppt)₂ forming a V-shaped chain. Compound 3 consists of a ladder structure, in which each {MoO₄} unit is a bridge linking three Zn(Hppt)²⁺ fragments.     

Synthesis and structures of complexes ofN-(2-aminoethyl)diaziridines with transition metal salts

A series of complexes ofN-(2-aminoethyl)diaziridines with transition metal salts (Zn²⁺, Cd²⁺, Ni²⁺, Co²⁺, Mn²⁺, or Fe²⁺) were synthesized. Their structures were established by IR and NMR spectroscopy. The structure of bis[1,2-bis(2-aminoethyl)diaziridine]cadmium(II) diperehlorate was confirmed by X-ray diffraction analysis. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1910–1914, November, 2000.     

Unusual reaction of 5-benzoyl-3-ethoxycarbonyl-6-methylthio-1-r-1,2-dihydropyridin-2-ones with nitrogen-containing 1,4-dinucleophiles

The reaction of 5-benzoyl-3-ethoxycarbonyl-6-methylthio-1-R-1,2-dihydropyridin-2-ones with the nitrogen-containing 1,4-dinucleophiles o-phenylenediamine, o-aminothiophenol, and ethylenediamine, proceeds as a recyclization, the products of which are derivatives of 5-(1H-benzimidazol-2-yl)-2H-2-pyranone, 5-(benzothiazol-2-yl)-2H-2-pyranone, and 5-(4,5-dihydro-1H-imidazol-2-yl)-2H-2-pyra-none respectively. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1089–1095, July, 2008.     

Chemistry of Spontaneous Alkylation of Methimazole with 1,2-Dichloroethane

Spontaneous S-alkylation of methimazole (1) with 1,2-dichloroethane (DCE) into 1,2-bis[(1-methyl-1H-imidazole-2-yl)thio]ethane (2), that we have described recently, opened the question about its formation pathway(s). Results of the synthetic, NMR spectroscopic, crystallographic and computational studies suggest that, under given conditions, 2 is obtained by direct attack of 1 on the chloroethyl derivative 2-[(chloroethyl)thio]-1-methyl-1H-imidazole (3), rather than through the isolated stable thiiranium ion isomer, i.e., 7-methyl-2H, 3H, 7H-imidazo[2,1-b]thiazol-4-ium chloride (4a, orthorhombic, space group Pnma), or in analogy with similar reactions, through postulated, but unproven intermediate thiiranium ion 5. Furthermore, in the reaction with 1, 4a prefers isomerization to the N-chloroethyl derivative, 1-chloroethyl-2,3-dihydro-3-methyl-1H-imidazole-2-thione (7), rather than alkylation to 2, while 7 further reacts with 1 to form 3-methyl-1-[(1-methyl-imidazole-2-yl)thioethyl]-1H-imidazole-2-thione (8, monoclinic, space group P 2₁/c). Additionally, during the isomerization of 3, the postulated intermediate thiiranium ion 5 was not detected by chromatographic and spectroscopic methods, nor by trapping with AgBF₄. However, trapping resulted in the formation of the silver complex of compound 3, i.e., bis-{2-[(chloroethyl)thio]-1-methyl-1H-imidazole}-silver(I)tetrafluoroborate (6_, monoclinic, space group P 2₁/c), which cyclized upon heating at 80 °C to 7-methyl-2H, 3H, 7H-imidazo[2,1-b]thiazol-4-ium tetrafluoroborate (4b, monoclinic, space group P 2₁/c). Finally, we observed thermal isomerization of both 2 and 2,3-dihydro-3-methyl-1-[(1-methyl-1H-imidazole-2-yl)thioethyl]-1H-imidazole-2-thione (8), into 1,2-bis(2,3-dihydro-3-methyl-1H-imidazole-2-thione-1-yl)ethane (9), which confirmed their structures.     

反式-1,2-双[5-取代苯基(口恶)唑-2-基]-乙烯的构象

合成了反式-1,2-双[5-(2,4,6-三甲基苯基)(口恶)唑-2-基]乙烯(1_a),并用分子力学法(MMX程序)计算了标题化合物(POEOP,2,5-二甲基-POEOP及2,4,6-三甲基POEOP).POEOP的结构、构象与X衍射结果颇吻合,分子中2个(口恶)唑环呈稳定的反向排布.比同向排布稳定4.6kJ/mol,旋转能垒约16.8～20.9 kJ/mol.还讨论了标题系列化合物的构象对其紫外光谱的影响.     

Synthesis of 2-[2-(5-phenyl-1,2,4-oxadiazol-3-yl)-ethyl]benzimidazole and its x-ray analysis

Cyclization of O-benzoyl-2-(benzimidazol-1-yl)propioamidoxime under different temperature conditions gave 2-[2-(5-phenyl-1,2,4-oxadiazol-3-yl)ethyl]benzimidazole whose structure has been determined by X-ray analysis. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1057–1061, July, 2006.     

反式-1,2-双[5-(2,5-二甲基苯基)(口恶)唑-2-基]-环丙烷的晶体结构与构象

合成了标题化合物并测定其晶体结构.晶体属P2₁/c空间群,a=1.3465(2)nm,b=0.8021(1)nm,c=1.9277(37)nm;β=105.99(1)°,Z=4.分子力学法计算与测定结果一致,环丙烷环与噁唑环间呈g式构象,与噁唑环π体系间有共轭效应,讨论了构象对紫外光谱的影响.     

Novel Aspects of the Reaction of 3-(Benzimidazol-2-yl)-2-iminocoumarins with Aromatic Aldehydes

The reaction of 3-(benzimidazol-2-yl)-2-iminocoumarins with aromatic aldehydes has been studied. The condensation products 7-aryl-7H-benzo[4,5]imidazo[1,2-c]benzopyrano[3,2-e]pyrimidines or 3-(benzimidazol-2-yl)coumarins are formed depending on the nature of the substituent in the starting 2-iminocoumarin and aldehyde. In DMF medium, 7-aryl-7H-benzo[4,5]imidazo[1,2-c]benzopyrano[3,2-e]pyrimidines isomerize to the corresponding 7-aryl-14H-benzo[4,5]imidazo[1,2-c]benzopyrano[3,2-e]pyrimidines. The effect of the substituent on the isomerization process has been studied and the reaction mechanisms are discussed.