Structure and dehydrogenation of silylated dihydroanthracenes. A new route to 9- and 9,10-silylated anthracenes

Mono- and di-silylated derivatives of 9,10-dihydro anthracene have been prepared. The cis and trans isomers of the disilylated compounds were separated and their configurations assigned. Attempted dehydrogenation of the derivatives with sulphur and chloranil led to the formation of anthracene, whereas with n-BuLi/TMED high yields of the corresponding silylated anthracenes were obtained. This affords a new and improved method of synthesis of 9- and 9,10-silylated anthracenes. The mass spectra of the derivatives are also discussed.     

Marcus theory of outer-sphere heterogeneous electron transfer reactions: dependence of the standard electrochemical rate constant on the hydrodynamic radius from high precision measurements of the oxidation of anthracene and its derivatives in nonaqueous solvents using the high-speed channel electrode

The validity of Marcus theory for outer-sphere heterogeneous electron transfer for the electro-oxidation of a range of anthracene derivatives in alkyl cyanide solvents is investigated. The precision measurement of these fast electron transfers (k(0) >or= 1 cm s(-1)) is achieved by use of the high-speed channel electrode and, where necessary, fast-scan cyclic voltammetry. First, the solvent effect on the rate of electron transfer is studied by considering the first oxidation wave of 9,10-diphenylanthracene in the alkyl cyanide solvents: acetonitrile, propionitrile, butyronitrile, and valeronitrile. Second, the variation of k(0) for a series of substituted anthracenes is investigated by analyzing the voltammetric response of the one-electron oxidations of 9-phenylanthracene, 9,10-dichloroanthracene, 9-chloroanthracene, 9,10-dicyanoanthracene, 9-cyanoanthracene, 9-nitroanthracene, 9,10-diphenylanthracene, and anthracene in acetonitrile. It is shown that the rate of electron transfer of a single compound in different alkyl cyanides is determined by the longitudinal dielectric relaxation properties of the solvent, while differences in rate between the substituted anthracenes in acetonitrile can be quantitatively rationalized by considering their relative hydrodynamic radii. This makes possible the accurate prediction of electron-transfer rates for a molecule by interpolation of rate constants known for related molecules.     

9,10‐Diaminoanthracenes Revisited: The Influence of N‐Substituents on Their Electronic States

The electronic and molecular structures of 9,10‐diamino‐substituted anthracenes with different N‐substituents have been re‐examined. In particular, different N‐substituents influence both the electronic and molecular structures of the oxidized species of 9,10‐diaminoanthracenes. The anthrylene moiety of 9,10‐bis(N,N‐di(p‐anisyl)amino)anthracene retains its planarity during the course of two successive one‐electron oxidations, whereas 9,10‐bis(N,N‐dimethylamino)anthracene and 9,10‐bis(N‐p‐anisyl‐N‐methylamino)anthracene undergo a substantial structural change to a butterfly‐like structure through a two‐electron oxidation process. The structural changes observed for the oxidized states are ascribed to significant differences in the frontier molecular orbitals of the above‐mentioned three kinds of 9,10‐diaminoanthracenes due to different extents of mixing between the amine‐localized and anthrylene‐localized orbitals.     

Efficient preparation of monoadducts of [60] fullerene and anthracenes by solution chemistry and their thermolytic decomposition in the solid state

The efficient preparation of monoadducts of [60]fullerene and seven anthracenes (anthracene, 1-methylanthracene, 2-methylanthracene, 9-methylanthracene, 9,10-dimethylanthracene, 2,3,6,7-tetramethylanthracene, and 2,6-di-tert-butylanthracene) by cycloaddition in solution is described. The seven mono-adducts of [60]fullerene and the anthracenes were characterized spectroscopically and were obtained in good yields as crystalline solids. The monoadducts of [60]fullerene and anthracene, 1-methylanthracene, 2-methylanthracene and 9,10-dimethylanthracene crystallized directly from the reaction mixture. The thermolytic decomposition at 180 degrees C of the crystalline monoadducts of [60]fullerene and anthracene, 1-methylanthracene, 9-methylanthracene and 9,10-dimethylanthracene all gave rise to the specific formation of a roughly 1:1 mixture of [60]fullerene and the corresponding antipodal bisadducts ("trans-1"-bisadducts) of [60]fullerene and the anthracenes. In contrast, the crystalline monoadducts of [60]fullerene and the anthracene derivatives 2-methylanthracene, 2,3,6,7-tetramethylanthracene and 2,6-di-tert-butylanthracene all decomposed to [60]fullerene and anthracenes (without detectable formation of bisadducts) upon heating in the solid state to temperatures of 180 to 240 degrees C. The formation of the antipodal bisadducts from thermolytic decomposition of crystalline samples of the monoadducts was rationalized by topochemical control.     

Regioselective `One‐Pot' Synthesis of Antipodal Bis‐adducts by Heating of Solid [5,6]Fullerene‐C60‐Ih and Anthracenes,Preliminary Communication

Antipodal (`trans‐1') Diels‐Alder bis‐adducts 3 and 7 – 9 of [5,6]fullerene‐C₆₀‐I_h ( 1 ) with some anthracenes were prepared highly regioselectively by heating mixtures of the solid 1 and anthracene or of (one of) three alkyl‐substituted anthracenes in the absence of solvents (Scheme 2). Other bis‐cycloadducts were not detected, but lesser amounts of mono‐cycloadducts 2 and 4 – 6 , respectively, were also formed. Heating of solvent‐free mixtures of 1 and three other alkyl‐substituted anthracenes did not result in a detectable amount of (antipodal) bis‐cycloadducts. The antipodal bis‐adduct 7 of 1 and of 1‐methylanthracene was analyzed by X‐ray crystallography. The preparative outcome of heating of anthracenes and solid 1 parallels the result of the heating of the corresponding crystalline mono‐adducts of anthracenes and 1 . Both approaches reveal a remarkably consistent dependence of the reaction upon the presence and position of alkyl substituents at the anthracene unit. The regioselective assembly of antipodal bis‐adducts from anthracene(s) and 1 cannot be rationalized by their (inherent molecular) stability, but it indicates the crucial control of the lattice.     

Formal [4 + 4] cycloaddition of 3-arylcyclobutanones with anthracene and their acid-promoted intramolecular cyclization with skeletal rearrangement

A reaction of 3-arylcyclobutanones with anthracene in the presence of TiCl₄ gave 14-aryl-9,10-dihydro-9,10-butanoanthracen-12-ones as a formal [4 + 4] cycloadduct of anthracenes with a C4 unit formed by cleaving the more substituted C2C3 bond of cyclobutanones. On the other hand, activation of 3-arylcyclobutanones with TfOH in the absence of nucleophiles gave 2-tetralones with skeletal rearrangement.     

Molecular polarizability of organic compounds and their complexes: LV. Molar volume and structure of some nitrogen compounds,their structural analogues,and some sterically hindered systems in solution

The molar volumes in solutions of a wide range of aliphatic and alicyclic amines, substituted acetanilides, 9- and 9,10-substituted anthracenes, and 1- and 1,8-substituted naphthalenes were estimated and discussed. Conformations of alkyl substituents in the aliphatic amines are similar to the conformations of the respective alkanes. Conformations (chair) of the molecules of alicyclic amines and cyclohexane are almost identical. In the molecules of acetanilides, the C(O)CH₃ group is conjugated with aromatic ring and is oriented toward the latter and toward the nitrogen of the amide group in the same manner as in acetophenone. A systematic decrease in the values of the molar volume increments of the substituents R in going from substituted benzene to substituted naphthalene and anthracene was revealed, which indicates the extension of the π-systems over the C-R bond. The orientation of 1,8-substituents relative to the naphthalene ring was found to be approximately orthogonal. A possibility to simplify the methods for determining the dipole moments and Kerr constants of compounds on the basis of their additive molar volumes was demonstrated.     

Electronic properties of anthracene derivatives for blue light emitting electroluminescent layers in organic light emitting diodes: a density functional theory study

Molecular level parameters are investigated computationally to understand the factors that are responsible for the higher efficiency in derivatives of 9,10-bis(1-naphthyl)anthracene (alpha-ADN), 9,10-bis(2-naphthyl)anthracene (beta-ADN), their tetramethyl derivatives (alpha,beta-TMADN) and the t-Bu derivative (beta-TBADN) as blue light emitting electroluminescent (EL) layers in organic light emitting diodes (OLEDs). DFT studies at the B3LYP/6-31G(d,p) level have been carried out on the substituted anthracenes. The absorption spectra are simulated using time dependent DFT methods (TD-DFT) whereas the emission spectra are approximated by optimizing the excited state by HF/CI-Singles and then carrying out the vertical CI calculations by the TD-DFT method. The reorganization energy for estimating the hole and electron transport is calculated. The transfer integrals between parallely stacked molecules in the bulk state are estimated by calculating the electronic splitting. The substituted anthracenes are compared with unsubstituted anthracene and yet untested 9,10-dianthrylanthracene (TANTH). A larger and slower buildup of the electrons and holes in the EL layer, due to the higher reorganization energy and smaller electronic coupling between the adjacent molecules could lead to an increase in hole-electron recombination in the layer and thus increase the efficiency.     

Mono-Aryl/Alkylthio-Substituted (Hetero)acenes of Exceptional Thermal and Photochemical Stability by the Thio-Friedel–Crafts/Bradsher Cyclization Reaction

The highly substituted mono-aryl/alkylthio-(hetero)acenes prepared in this study have been found to be thermally more stable (T_decomp.=331–354 °C) than the known di-aryl/alkylthio-substituted acenes by an average of 25 °C. They are also much more photostable at 254 and 365 nm (in both argon and air) than the parent anthracene and other reported anthracenes. The most photostable aryl/alkylthio-anthracenes at 254 nm were found to be 60–70 (in air) and 130 (in argon) times more stable in solution than the unsubstituted anthracene, and much more stable than known EDG/EWG-substituted anthracenes (EDG=electron-donating group, EWG=electron-withdrawing group) with an extended aromatic core. Furthermore, the acenes showed significantly higher photostability at 365 nm in both air and argon. The anthracenes were obtained by the novel thio-Friedel–Crafts/Bradsher cyclization reaction of hitherto unknown [o-(1,3-dithian-2-yl)aryl](aryl)methyl thioethers. The developed approach provides a general access to mono-aryl/alkylthio-substituted (hetero)acene frameworks containing at least three fused (hetero)aromatic rings. The characteristic feature of this approach, which leads to highly substituted acenes, is that the substituents, unlike in other methods, may be introduced at an early stage of the synthesis. DFT and TD-DFT calculations confirmed the stabilizing role of the aryl/alkylthio substituent in the mono-aryl/alkylthio-substituted anthracenes, which are the most stable anthracenes prepared to date. Their high photostability is mainly due to the quenching of singlet oxygen by the acene and the quenching of the acene S₁ state by molecular oxygen.     

Etude par polarisation nucleaire induite chimiquement de la reaction photochimique de l'anthracene avec des tetrahalogenomethanes

The photoreaction of anthracene with CCl₄, CCl₃Br or CBr₄ was studied by CIDNP. The primary products of the reaction (polyhalogeno 9,10-dihydro anthracenes) are thermally unstable, but evidence was shown for their existence. The initiating radical pair of this reaction is: $\text{9-chloro 10-anthryl/trichloromethyl}$^S. This study was extended to 9-methyl and 9,10-dimethyl anthracenes.     

Synthesis of monodisperse oligocarbazoles-functionalized anthracenes with intense blue-emitting

New well-defined monodisperse oligocarbazoles-functionalized anthracenes An-OCZn (n = 1, 2, 3) have been synthesized through Suzuki cross-coupling reaction of the brominated oligocarbazoles and 9,10-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)anthracene. They show good solubility in organic solvents, including dichloromethane, chloroform, toluene, ethyl acetate, and tetrahydrofuran. It should be noted that, in the case of An-OCZn, the formation of the excimer based on anthracene unit is suppressed completely due to the introduction of oligocarbazoles in 9,10-position of anthracene so that an intense blue-emitting has been afforded. In addition, the obtained An-OCZn exhibit good electrochemical and thermal stabilities. Thus, the oligocarbazoles-functionalized anthracenes can be a class of promising candidates for novel blue-emitting materials employed in OLEDs or related devices.     

2-(10-Diazo-10H-anthracen-9-ylidene)-malonodinitrile: A convenient precursor of 9,10-disubstituted anthracenes

Summary The acid promoted decomposition of 2-(10-diazo-10H-anthracen-9-ylidene)-malonodinitrile in the presence of water, methanol, ethanol, acetic and propionic acid, ethyl thioglycolate,p-thiocresole, and acetyl acetone yielding 9,10-disubstituted 9,10-dihydroanthracenes was investigated. Treatment of the reaction products with tri-ethyl amine followed by hydrochloric acid caused their tautomerization to the corresponding 9,10-disubstituted anthracenes. A mechanism for this reaction is proposed. The first example of an intermolecular C-C-bond formation during the protic acid promoted decomposition of a diazo compound in the presence of CH-acids was found. An improved procedure for the preparation of the starting diazo compound, which may serve as a convenient precursor of 9,10-disubstituted anthracenes, is described.Cordially dedicated to Prof. Dr.K. Winsauer on the occasion of his 70^th birthday     

Photocatalytic oxygenation of anthracenes and olefins with dioxygen via selective radical coupling using 9-mesityl-10-methylacridinium ion as an effective electron-transfer photocatalyst

Visible light irradiation of the absorption band of 9-mesityl-10-methylacridinium ion (Acr+-Mes) in an O2-saturated acetonitrile (MeCN) solution containing 9,10-dimethylanthracene results in formation of oxygenation product, i.e., dimethylepidioxyanthracene (Me2An-O2). Anthracene and 9-methylanthracene also undergo photocatalytic oxygenation with Acr+-Mes to afford the corresponding epidioxyanthracenes under the photoirradiation. In the case of anthracene, the further photoirradiation results in formation of anthraquinone as the final six-electron oxidation product, via 10-hydroxyanthrone, accompanied by generation of H2O2. When anthracene is replaced by olefins (tetraphenylethylene and tetramethylethylene), the photocatalytic oxygenation of olefins affords the corresponding dioxetane, in which the O-O bond is cleaved to yield the corresponding ketones. The photocatalytic oxygenation of anthracenes and olefins is initiated by photoexcitation of Acr+-Mes, which results in formation of the electron-transfer state: Acr*-Mes*+, followed by electron transfer from anthracenes and olefins to the Mes*+ moiety together with electron transfer from the Acr* moiety to O2. The resulting anthracene and olefin radical cations undergo the radical coupling reactions with O2*- to produce the epidioxyanthracene (An-O2) and dioxetane, respectively.     

A new access to the anthracene core: Synthesis of two water soluble singlet oxygen traps derived from 1,3-diphenylisobenzofuran and 9,10-diphenylanthracene

Two water soluble¹O₂ traps: dipotassium 1,3 - diphenylisobenzofuran - 5,6 - dicar?ylate and tetrapotassium 9,10 - diphenylanthracene - 2,3,6,7 - tetracar?ylate have been prepared in good yields and a new access to the anthracene skeleton is described. The key-step of this synthesis consists of a cycloaddition between 1,3 - diphenylisobenzofurans and dimethyl 7 - oxabicyclo[2.2.1] - 5 - heptene - 2,3 - dicar?ylate; the adducts thus obtained undergo dehydration to afford the corresponding anthracenes.     

Intramolecular behaviors of anthryldicarbenic systems: dibenzo[b,f]pentalene and 1H,5H-dicyclobuta[de,kl]anthracene

9,10-Bis[methoxy(trimethylsilyl)methyl]anthracenes (24), synthesized from 9,10-dilithioanthracene (26) and bromomethoxytrimethylsilylmethane (27, 2 equiv), decompose (550-650 degrees C/10(-3) mmHg) carbenically to dibenzo[b,f]pentalene (28, > 48%). 9,10-Anthryldicarbenes 39 or their equivalents convert to pentalene 28 rather than di-peri-cyclobutanthracenes 30 and 31, benzobiphenylene 32, or extended rearrangement products 33-38. Formation of 28 from 24 raises questions with respect to the behavior of 1,3,4,6-cycloheptatetraenyl-1-carbenes 49, 2,4,5,7-cyclooctatetraenylidene 51, 2,5,7-cyclooctatriene-1,4-diylidene 52, 1,2,4,5,7-cyclooctapentaene 53, and bicyclo[4.1.0]heptatrienyl-1-carbenes 54 and to carbon-skeleton and hydrogen rearrangements of anthryldicarbenes 39 and/or their equivalents at various temperatures. 1,5-Bis[methoxy(trimethylsilyl)methyl]anthracenes (25), prepared from 1,5-diiodoanthracene (63) and methoxytrimethylsilylmethylzinc bromide (57, 2 equiv) as catalyzed by PdCl(2)(PPh(3))(2), yield the di-peri-carbenic reaction product 1H,5H-dicyclobuta[de,kl]anthracene (30, > 40%) on pyrolysis at 550-650 degrees C/10(-3) mmHg. Proof of structure and various aspects of the mechanisms of formation of 30 are discussed.     

Synthesis and liquid crystal properties of some 2,6‐disubstituted anthracenes

The synthesis and liquid crystalline properties of some new 2,6‐disubstituted anthracenes are described. Symmetrical alkylphenyl derivatives exhibit smectic mesophases, whereas simpler structures are non‐mesogenic. One unsymmetrically substituted anthracene exhibits a narrow nematic phase. The potential for these molecules to act as phototriggers has been investigated but efficient photodimerisation cannot be achieved.     

Supramolecular-induced regiocontrol over the photochemical [4 + 4] cyclodimerization of NHC- or azole-substituted anthracenes

Thanks to the impressive control that microenvironments within enzymes can have over substrates, many biological reactions occur with high regio- and stereoselectivity. However, comparable regio- and stereoselectivity is extremely difficult to achieve for many types of reactions, particularly photochemical cycloaddition reactions in homogeneous solutions. Here, we describe a supramolecular templating strategy that enables photochemical [4 + 4] cycloaddition of 2,6-difunctionalized anthracenes with unique regio- and stereoselectivity and reactivity using a concept known as the supramolecular approach. The reaction of 2,6-azolium substituted anthracenes H₄-L(PF₆)₂ (L = 1a–1c) with Ag₂O yielded complexes anti-[Ag₂L₂](PF₆)₄ featuring an antiparallel orientation of the anthracene groups. Irradiation of complexes anti-[Ag₂L₂](PF₆)₄ proceeded under [4 + 4] cycloaddition linking the two anthracene moieties to give cyclodimers anti-[Ag₂(2)](PF₆)₂. Reaction of 2,6-azole substituted anthracenes with a dinuclear complex [Cl-Au-NHC–NHC-Au-Cl] yields tetranuclear assemblies with the anthracene moieties oriented in syn-fashion. Irradiation and demetallation gives a [4 + 4] syn-photodimer of two anthracenes. The stereoselectivity of the [4 + 4] cycloaddition between two anthracene moieties is determined by their orientation in the metallosupramolecular assemblies.

A supramolecular templating strategy that enables the photochemical [4 + 4] cycloaddition of 2,6-difunctionalized anthracene derivatives with unique stereoselectivity has been developed based on metal-NHC units.     

Fused multifunctionalized bridge aromatic hydrocarbons from in situ-generated arynes and anthracene derivatives

This study presents a facile strategy for the formation of highly substituted butterfly 1,4-adducts/9,10-adducts via the Diels–Alder reaction of benzyne intermediates. The method achieves very good to excellent yields of the respective anthracene derivatives under mild conditions. This practical protocol is compatible with a variety of sensitive functional groups and provides access to difunctionalized bridge 1,4-adducts/9,10-adducts.     

Diels–alder reactions of anthracenes with C‐sulfonyldithioformates

C‐Sulfonyldithioformates ( 2 ) (R¹ = ArSO₂, R² = ArS) readily add to anthracene and 9‐methylanthracene ( 1 ) in a Diels–Alder fashion with formation of 9,10‐dihydro‐10,9‐(epithiomethano)anthracenes ( 3 ) which in turn may suffer thermally induced elimination of arenesulfinic acid to yield the 9‐anthracenedithiocarboxylic esters ( 4 ). The reactions with the unsymmetrical diene 9‐methylanthracene take place in a highly stereoselective fashion. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:170–174, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10119     

9,10-双-(对-(甲氧基二缩三乙二醇基)苯基乙炔基)蒽的合成、自组装及其光谱分析

通过Sonogashira偶联等反应,合成了三嵌段化合物9,10-双-(对-(甲氧基二缩三乙二醇基)苯基乙炔基)蒽,通过¹H NMR和基质辅助激光解吸电离时间飞行质谱(MALDI-TOF-MS)对其结构进行了表征。利用差示扫描量热仪(DSC)、偏光显微镜(POM)及小角X射线散射仪(SAXS)等技术手段对其本体自组装行为进行了研究,结果表明,化合物在固态相自组装成近晶A相(SmA相)。光谱分析表明,该化合物继承了二取代蒽类发光材料具有高荧光量子产率(Φ_f)的特点,是一种性能良好的光致发光材料。