Synthesis and self-aggregation of cyclic alkynes containing helicene

[structure: see text]. All stereoisomers of a cyclic alkyne containing three helicene units, 1,12-dimethylbenzo[c]phenanthrene, are synthesized using a building block. Isomeric [3 + 3]cycloalkynes aggregate in organic solvents. Vapor pressure osmometry reveals dimer formation of (M,M,M)-[3 + 3]cycloalkynes in chloroform and benzene at concentrations above 2 mM. No higher aggregation is observed. The chirality of helicenes plays an important role in self-aggregation, and diastereomeric (M,P,M)-[3 + 3]cycloalkyne forms a dimer only above 15 mM. Aggregation of racemic (M,M,M)-[3 + 3]cycloalkyne or (M,P,M)-[3 + 3]cycloalkyne is much weaker than that of a single enantiomer.     

Functionalized [3 + 3]cycloalkynes: substituent effect on self-aggregation by nonplanar pi-pi interactions

[reaction: see text] Optically active (M)-2,11-dihydroxy-1,12-dimethylbenzo[c]phenanthrene-5,8-dicarbonitrile was synthesized from (M)-1,12-dimethyl-2,11-dinitrobenzo[c]phenanthrene-5,8-dicarbonitrile by the reduction and hydroxylation of nitro groups. The compound was converted to several oxygen-functionalized [3 + 3]cycloalkynes with -OH, -OSiMe2-t-Bu, -OAc, -OTf, or -ONf groups, which are chiral arylene ethynylene macrocycles containing three helicenes. The aggregation behaviors of these [3 + 3]cycloalkynes were examined in CHCl3, THF, and acetone using 1H NMR, CD, and vapor pressure osmometry (VPO) studies and were compared with that of the parent [3 + 3]cycloalkyne. An increasing strength of aggregation in CHCl3 was observed in the following order of the substituted derivatives: -H > -ONf > -OTf > -OAc > -OSiMe2-t-Bu. In THF the following strength of aggregation was observed: -OTf > -ONf > -OAc > -H > -OSiMe(2)-t-Bu > -OH. The aggregation of the functionalized [3 + 3]cycloalkynes is stronger for the compounds with electron-withdrawing substituents than for those with electron-donating substituents. (M)-1,12-dimethylbenzo[c]phenanthrene-2,5,8,11-tetraol was also synthesized from the same intermediate. This electron-rich helicene was readily oxidized to 5,6-quinone in air, and the quinone was suggested to form a self-charge-transfer complex in solid state.     

Synthesis and ring size effect of macrocyclic ethynylhelicene oligomers

[reaction: see text] The cyclization of acyclic ethynylhelicene oligomers with decyl 3,5-diiodobenzoate under optimized conditions gave the corresponding optically active [n+n]cycloalkynes (n = 4-8) in high yields. Their structures were compared in terms of ring size by using (1)H NMR, UV-vis, and CD spectroscopies and vapor pressure osmometry (VPO). The UV-vis spectra exhibited an increase in absorbance in proportion to n. In contrast, the CD spectra of the macrocycles exhibited a large ring size effect, comparable Deltaepsilon values despite the increase in n and temperature-dependent properties of the [8+8]cycloalkyne. It was concluded that [4+4]cycloalkyne, [5+5]cycloalkyne, [6+6]cycloalkyne, and [7+7]cycloalkyne have rigid structures, while [8+8]cycloalkyne has a flexible structure.     

Two azo pigments based on β‐naphthol

There has been much discussion in the literature of the azo–hydrazone tautomerism of pigments. All commercial azo pigments with β‐naphthol as the coupling compound adopt the hydrazone tautomeric form (Ph—NH—N=C) in the solid state. In contrast, the red pigments 1‐[4‐(dimethylamino)phenyldiazenyl]‐2‐naphthol, C₁₈H₁₇N₃O, (1a), and 1‐[4‐(diethylamino)phenyldiazenyl]‐2‐naphthol, C₂₀H₂₁N₃O, (1b), have been reported to be azo tautomers or a mixture of azo and hydrazone tautomers in the solid state. To prove these observations, both compounds were synthesized, recrystallized and their crystal structures redetermined by single‐crystal structure analysis. Difference electron‐density maps show that the H atoms of the hydroxyl groups are indeed bonded to the O atoms. Nevertheless, a small amount of the hydrazone form seems to be present. Hence, the compounds are close to being `real' azo compounds. Compound (1a) crystallizes with a herring‐bone structure and compound (1b) forms a rare double herring‐bone structure.     

Geminal bis-ureas as gelators for organic solvents: gelation properties and structural studies in solution and in the gel state

Several geminal bis-urea compounds were synthesised by means of an acid-catalysed condensation of various benzaldehydes with different monoalkylureas. Many of these compounds form thermoreversible gels with a number of organic solvents at very low concentrations (<3mM) and which are stable to temperatures higher than 100 degrees C. Electron microscopy revealed a three-dimensional (3D) network of intertwined fibres, which are several tens of micrometers long and have a width ranging from approximately 30 to 300 nm. The possible aggregate forms and aggregate symmetries were evaluated by means of molecular mechanics calculations. 1H NMR, 2D NMR, 13C NMR and 13C-CP/MAS NMR techniques were used to obtain information about the aggregation and possible aggregate symmetry of geminal bis-ureas in solution, in the gel state, and in the solid state.     

Efficient and Selective Extraction of Fe3+ by Mono- and Di-Azocalix[4]arene Derivatives

Nine series of chromogenic mono- (A1-A2) and di- (B1-B7) substituted azocalix[4] arene analogues containing more than one azo group were described. Different chelating agents like ester and ketone moieties were grafted on the lower rim position of azocalix[4]arenes. The selective extraction properties of Fe³⁺ cation were studied by liquid-liquid extraction. This extraction process was carried out by using compounds A1-A2 and B1-B7. The results proved that coupling of phenylazo groups onto the upper rim of azocalix[4]arenes yielded greater efficiency and selectivity for carrying the Fe³⁺ cation in the extraction process at pH 2.2.     

Photochemistry of 6,6-Dimethyl- and 2,2,6,6-Tetramethyl-2H,6H-pyran-3-one

The title compounds 1a and 1b have been synthesized in two steps from the saturated pyran-3-ones 2a and 2b , respectively. Upon irradiation (254 nm or 350 nm) in dilute solutions (10^?3?10^?2M ), compounds 1 undergo a formal [4 + 2] cycloreversion from the excited triplet state to give (2-methylprop-1-enyl)ketene ( 11 ) and either formaldehyde or acetone, ketene 11 being trapped by H₂O or MeOH to afford 4-methylpent-3-enoic acid ( 5 ) or its methyl ester 4 in 75–85% isolated yield. In this (monomolecular) photoreaction, heterocycles 1 differ from their alicyclic counterparts, i.e., 4,4-dimethylcyclohex-2-enone ( 10a ) and 4,4,6,6-tetramethylcyclohex-2-enone ( 10b ), as no rearrangement to a 4-oxabicyclo[3.1.0]hexan-2-one occurs. On the other hand, the photochemical behavior of pyranone 1a in bimolecular reactions (cyclodimerization, [2 + 2] cycloaddition to 2,3-dimethylbut-2-ene) resembles that of enone 10a .     

Photochemical upconversion approach to broad-band visible light generation

The sensitized triplet-triplet annihilation (TTA) of 9,10-dimethylanthracene (DMA) upon selective excitation of [Ru(dmb)3]2+ (dmb = 4,4'-dimethyl-2,2'-bipyridine) at 514.5 nm in dimethylformamide (DMF) resulted in upconverted and downconverted DMA excimer photoluminescence. The triplet excited state of [Ru(dmb)3]2+ is efficiently quenched by 11 mM DMA in DMF resulting in photon upconversion but no excimer formation. The bimolecular quenching constant of the dynamic quenching process is 1.4 x 109 M-1 s-1. At 90 mM DMA, both upconversion and downconversion processes are readily observed in aerated DMF solutions. The TTA process was confirmed by the quadratic dependence of the upconverted and downconverted emission emanating from the entire integrated photoluminescence profile (400-800 nm) of DMA measured with respect to incident light power. Time-resolved emission spectra of [Ru(dmb)3]2+ and 90 mM DMA in both aerated and deaerated DMF clearly illustrates the time-delayed nature of both types of singlet-state emission, which interestingly shows similar decay kinetics on the order of 14 mus. The emission quantum yields (Phi) measured using relative actinometry increased with increasing DMA concentrations, reaching a plateau at 3.0 mM DMA (Phi = 4.0%), while at 90 mM DMA, the overall quantum yield diminished to 0.5%. The dominant process occurring at 3.0 mM DMA is upconversion from the singlet excited state of DMA, whereas at 90 mM DMA, both upconversion and excimeric emission are observed in almost equal portions, thereby resulting in an overall broad-band visible light-emission profile.     

Azobridges from azines, XVII. Intra- and intermolecular [3+2] cycloaddition between nonstabilized azomethineimines and alkenes

Azo compounds 1 and 3 containing a CC-double bond in a parallel but distant position are quatemized by Me₃OBF₄ to 1,MeBF₄ and 3,MeBF₄, whereas MeI produces the cage compounds 2,HX and 4,HX. These [3+2] cycloadducts also are quantitatively formed from 1,MeBF₄ and 3,MeBF₄ with catalytic amounts of azo compounds. Intermolecular [3+2] cycloadditions occur with a mixture of DBH (5) or DBO (8), MeI and a variety of alkenes (→ HI) salts of (6, 7, 9 — 12). The intermediate azomethineimines, if stabilized by a fluorenylidene group, can be isolated (20, 22,24), but not, however, in the presence of a close parallel CC-bond (25 → 26).     

偶氮基杯芳烃化合物的合成及其偶氮-醌腙互变异构性质

通过芳胺的重氮化-偶合反应合成了8个偶氮基杯芳烃化合物, 其结构经IR, 1H NMR, ESI-MS和元素分析表征. 通过UV-Vis, 1H NMR和IR考察了溶液pH值对所合成化合物5,11,17,23-四[(2-苯并噻唑基)偶氮基]-25,26,27,28-四羟基杯芳烃(3)和5,17-二[(1-萘基)偶氮基]-25,26,27,28-四羟基杯芳烃(4)的偶氮-醌腙互变异构的影响. 结果表明, 随着溶液pH值增加, 醌腙体在偶氮-醌腙互变异构平衡中的比例增加, 当pH≥10时, 几乎全部转变为醌腙体. 特别当溶液pH=-1时, 化合物4可以形成一种大的共轭体系, 使其λmax由477 nm红移至545 nm.     

The synthesis of ferrocenyl- and ferrocenoylpyrimidines

New derivatives of pyrimidine were synthesized from ferrocenyl ketones by the reactions of [3+1+1+1]annulation and intermolecular cyclization. The electrochemical behavior of the obtained compounds was studied by the method of cyclic voltammetry. All the compounds may be characterized with the signal, corresponding to the reversible one-electron transfer in ferrocene-ferrecinium and lowering of the redox potential with respect to ferrocene.     

Studies in the imidazole series

6,7-Dimethylbenzimidazo[2,1-b]thiazolid-3-one was synthesized, and its reactions with aldehydes, isatin, nitroso compounds, and arene diazonium salts were studied. As a result, ylidene and imino derivatives and azo coupling products were obtained. According to the IR spectra, the azo coupling products have 6,7-dimethylbenzimidazo[2,1-b]thiazolidine-2,3-dione 2-arylhydrazone structures.See [1] for communication LVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 822–825, June, 1971.     

[3,3] Valenceisomeric azo bridged carbocycles and cyclic hydrazones: intramolecular [3+2] cycloaddition and [4+2] cycloreversions through n-methylation1

Unsaturated azo bridged carbocycles 1, 2, 5, 8, 12, 14 and 16 can easily be methylated with Me₃OBF₄ or MeI. Depending on structural and steric requirement and the anion, the quaternary salts obtained are stable (1-Me⁺, 2-Me⁺, 5a-Me⁺, 14a/b-Me⁺, 16a/b-Me⁺ with BF_4-), undergo [4+2] cycloreversion (8a-Ne⁺, 12-Me⁺) or intramolecular [3+2] cycloaddition after intermediate deprotonation, whereby the unusual hydrazine derivatives, the cage compounds 3-H⁺ , 4-H⁺, 6-H⁺ and 11-H⁺ are formed. Systems which contain the N=N and C=C function in 1,5-positions are isomeric with their [3,3] rearrangement products, the hydrazones endo-7, endo-10, endo-15 and endo-17. Methylation of the latter provokes the same consecutive reactions as for their azo isomers. These have been demonstrated to be the crucial intermediates for the formation of cage Compound (e.g. endo-7b-Me⁺ → 5b-Me⁺ → 6-H⁺ ). Intermolecular methyl migration of quaternized azo compounds has been established, explaining the high yields of cage compounds which can be produced by the “b-series” only.     

Supramolecular daisy chains

Two series of self-complementary daisy chain monomers, in which a secondary ammonium ion-containing arm is grafted onto a macrocycle with either a [24]- or [25]crown-8 constitution, have been synthesized. In the solid- and 'gas'-phases, the parent [24]crown-8-based monomer forms dimeric superstructures, as revealed by X-ray crystallography and mass spectrometry, respectively. Elucidation of the complicated solution-phase behavior of this compound was facilitated by the synthesis and study of both deuterated, and fluorinated, analogues. These investigations revealed that the cyclic dimeric superstructure also dominates in solution, except when extremes of either concentration (low), temperature (high), or solvent polarity (highly polar, e.g., dimethyl sulfoxide) are employed. Whereas, upon aggregation, the [24]crown-8-based daisy chain monomers have the capacity to form stereoisomeric superstructures further complicating the study of this series of compounds. The assembly of [25]crown-8-based monomers gives only achiral superstructures. The weaker association exhibited between secondary dialkylammonium ions and crown ethers with a [25]crown-8 constitution, however, resulted in limited oligomerization--only dimeric and trimeric superstructures were formed at experimentally attainable concentrations--of [25]crown-8-based daisy chain monomers.     

Synthesis of Bicyclic Imidazoles via [2 + 3] Cycloaddition between Nitriles and Regioselectively Generated α-Imino Gold Carbene Intermediates

The cyclic α-imino gold carbene intermediate B is most likely generated in situ via regioselective nitrene transfer from an azido group to a tethered terminal alkyne in the presence of a gold catalyst and at ambient temperature. This highly electrophilic intermediate can react with a weakly nucleophilic nitrile, which is used as the reaction solvent, to deliver a bicyclic imidazole rapidly in an overall bimolecular [2 + 2 + 1] cycloaddition and in mostly serviceable yield. The competing intramolecular Huisgen reaction, although likely also catalyzed by gold, is minimized by using AuCl(3) as the catalyst.     

Two stereoisomers of an S-bridged RhIII2PtII2 tetranuclear complex [{Pt(NH3)2}2{Rh(aet)3}2]4+ that lead to a discrete and a 1D RhIII2PtII2AgI structures by reacting with AgI (aet = 2-aminoethanethiolate)

An S-bridged RhIII2PtII2 tetranuclear complex having two nonbridging thiolato groups, [{Pt(NH3)2}2{Rh(aet)3}2]4+ ([1]4+), in which two fac(S)-[Rh(aet)3] units are linked by two trans-[Pt(NH3)2]2+ moieties, was synthesized by the 1:1 reaction of fac(S)-[Rh(aet)3] (aet = 2-aminoethanethiolate) with trans-[PtCl2(NH3)2] in water. Complex [1]4+ gave both the meso (DeltaLambda) and racemic (DeltaDelta/LambdaLambda) forms, which were separated by fractional crystallization. Of two possible geometries, syn and anti, which arise from the arrangement of two nonbridging thiolato groups, the meso and racemic forms of [1]4+ selectively afforded the anti and syn geometries, respectively. The DeltaLambda-anti and DeltaDelta/LambdaLambda-syn isomers of [1]4+ reacted with Ag+ using two nonbridging thiolato groups to produce a {RhIII2PtII2AgI}n) polymeric complex, {[Ag{Pt(NH3)2}2{Rh(aet)3}2]5+}n) ([2]5+), and a RhIII2PtII2AgI pentanuclear complex, [Ag{Pt2(mu-H2O)(NH3)2}{Rh(aet)3}2]5+ ([3]5+), respectively, which contain octahedral RhIII, square-planar PtII, and linear AgI centers. In [2]5+, each DeltaLambda-anti-[{Pt(NH3)2}2{Rh(aet)3}2]4+ tetranuclear unit is bound to two AgI atoms to form a one-dimensional zigzag chain, indicating the retention of the parental S-bridged structure in DeltaLambda-anti-[1]4+. In [3]5+, two Delta- or Lambda-fac(S)-[Rh(aet)3] units are linked by a [Pt2(mu-H2O)(NH3)2]4+ dinuclear moiety, together with an AgI atom, indicating that two NH3 molecules in [1]4+ have been replaced by a water molecule that bridges two PtII centers, while the parental DeltaDelta/LambdaLambda-syn configuration is retained. The complexes obtained were characterized on the basis of electronic absorption, CD, and NMR spectra, along with single-crystal X-ray analyses.     

内式及外式-5,5-二取代-3-氧代-4-氧杂三环[5,2,1,02,6]-8-癸烯类化合物的合成

由于许多降冰片烷衍生物及内酯类化合物都是很好的香原料,可用于调制化妆品或食用香精。为了探讨结构与香气的关系,并寻找新型的香原料,我们将上述两部分骨架-降冰片烷环系及内酯环系结合在一起,合成了具有如下结构的化合物16个。     

Formal gas-phase polar [4 + 1+] cycloaddition of ionized methylene to alpha-dicarbonyl compounds: synthesis of 2-unsubstituted 1,3-dioxoles

Ion/molecule reactions of +CH2OCH2. with alpha-dicarbonyl compounds were performed via pentaquadrupole mass spectrometry. Besides the previously known [3+ + 2] 1,3-cycloaddition reaction that forms cyclic 1,3-dioxonium ions, an unprecedented reaction proceeding formally by [4 + 1+] cycloaddition of ionized methylene (CH2+.) to the alpha-dicarbonyl compounds occurs competitively, leading to the gas-phase synthesis of several ionized 2-unsubstituted 1,3-dioxoles. This novel cycloaddition reaction may therefore be added to the set of methods available for the synthesis of 1,3-dioxoles.     

Synthesis and Optical Study of Sensitive and Selective Calix[4] Based Cu2+ Ion Detection Probes

Russian Journal of General Chemistry - Naked-eye colored chemo dosimeters based on symmetrical calix[4]azo dye conjugates A1–3 are synthesized and characterized. Calix[4]azo dye conjugates...     

Novel Disubstituted Calix[4]arenes Containing Chromogenic Groups on the Lower Rim: Synthesis,Structural Identification,and Absorption Properties

5,11,17,23‐Tetra‐tert‐butyl‐25,26,27,28‐tetrahydroxycalix[4]arene and 25,26,27,28‐tetrahydroxycalix[4]arene were synthesized based on previous literature. Firstly, several azo dyes were synthesized, and then, these dyestuffs were chlorinated through reaction with thionyl chloride. Secondly, the azo compounds bonded with methylene chloride and reacted with 25,26,27,28‐tetrahydroxycalix[4]arene, and then, six novel disazocalix[4]arene derivatives 4 ( a – f ) were achieved. Their structures were characterized as Fourier transform infrared, ¹H‐NMR, and elemental analysis. In this study, we investigated the solvatochromic properties of the compounds and the acid–base effect on their ultraviolet–visible absorption by using six solvents.