Phase Diagram of Na2S2O3)+t‐Butanol+Water at Ambient Pressure and Temperature

In the present work, we report the studies concerning liquid‐liquid‐solid equilibria for the ternary system sodium thiosulphate (Na₂S₂O₃)+t‐butanol+water at ambient pressure and at room temperature (303±2 K). The solubility data of Na₂S₂O₃ are reported for solutions in water, t‐butanol and solutions of varying concentrations of t‐butanol in water. The phase diagram for the said system is developed, described and compared with similar systems studied such as Na₂S₂O₃+ethanol+water, K₂CO₃+methanol+water, etc. These results have been explained in terms of structural properties of aqueous t‐butanol solutions and further discussed in terms of the effect of ions to cause phase separation.     

Room‐Temperature Phosphorescence of Crystalline Metal‐Free Organoboron Complex

The photoluminescence (PL) properties of a metal‐free organoboron complex, bis(4‐iodobenzoyl)methanatoboron difluoride ( 1BF₂ ), were elucidated. At room temperature, 1BF₂ emits blue fluorescence (FL) in nBuCl upon photoexcitation. In contrast, crystals of 1BF₂ emit green PL comprised of FL and phosphorescence (PH). The room‐temperature PH of crystalline 1BF₂ is a consequence of 1) suppression of thermal deactivation of the S₁ and T₁ excited states and 2) enhancement of intersystem crossing (ISC) from the S₁ to T₂ or T₁. The results of X‐ray crystallographic and theoretical studies supported the proposal that the former (1) is a result of intermolecular interactions caused by π‐stacking in the rigid crystal packing structure of 1BF₂ . The latter (2) is an effect of not only the heavy‐atom effect of iodine, but also the continuous π‐stacking alignment of 1BF₂ molecules in crystals, which leads to a forbidden S₁→S₀ transition and a small energy gap between the S₁ and T₂ or T₁.     

Formation and coordination of a terdentate dithiocarbazatopyrazoline derivative to technetium(V)

The potentially terdentate ligand 1-(S-methyldithio)-3,5-dimethyl-3-(S-methyldithiocarbazato)pyrazoline (H₂mdp) was prepared by the reaction of S-methyldithiocarbazate with acetylacetone in an acidic ethanol solution. The neutral complex [TcOCl(mdp)](1) was formed by the reaction of (n-Bu₄N)[TcOCl₄] with H₂mdp in ethanol at room temperature. Compound 1 has a square-pyramidal geometry with the thiolate, thiocarbonyl and amide donor atoms of the terdentate chelate mdp and chloride forming a square plane, with the oxo oxygen in the apical position.     

具有强蓝色荧光发射效应的二维四方格子化合物：萘普生锌配聚物

ZnCl₂和(S)-奈普生(H-奈普生)反应得到一个二维层状配位聚合物[Zn((S)-Naproxen)(OH)]_n (1)。这是第一个基于奈普生的配位聚合物，本文还提供了对奈普生和金属离子反应的新的见解。这一聚合物在室温下有很强的蓝色荧光并且具有一定的SHG效应。     

Cyclic sulfur nitrogen compounds and phosphorus reagents: Part XII. Reactions of S4N4 with (2-pyridylamino) phosphines [1]

Tetrasulfurtetranitride, S₄N₄ reacts with (2-pyridylamino)-diphenylphosphine in MeCN at room temperature to form the cyclotrithiazene (NC₅H₄NH)-Ph₂PN S₃N₃ ( 1 ) in good yield. By contrast, the cyclophosphathiazenes Ph₂PS₂N₃ ( 2 ) and 1,5(Ph₂P)₂S₂N₄ ( 3 ) are isolated from the same reaction mixture under reflux conditions. In solution, compound 1 is found to be transformed into 2 . The reaction of S₄N₄ with (2-pyridylamino)phenyl(dicyclohexylamino)phosphine in MeCN at room temperature affords Ph(DCA)PS₂N₃ ( 4 ) (DCA = dicylohexylamino) as the only reaction product. This on treatment with norbornadiene produces the addition product Ph(DCA)PS₂N₃·C₇H₈ ( 5 ). The structure of 4 has been established by X-ray diffraction. Its PSN ring adopts a skew boat conformation with S N bond lengths varying from 1.574(4) to 1.606(4) Å. The mean value of the endocyclic P N bonds amounts to 1.618(3) Å.     

Simple and Efficient Synthesis of 5-Substituted-3-phenyl-2-thioxoimidazolidin-4-one Derivatives from S-Amino Acids and Phenylisothiocyanate in Et3N/DMF-H2O

A concise approach for the transformation of various S-amino acids into the 5-alkyl-3-phenyl-2-thioxoimidazolidin-4-one heterocycles using phenylisothiocyanate is described. Phenylthiohydantoins of amino acid were synthesized at room temperature in Et₃N/DMF-H₂O with easy workup and excellent yields.     

One-pot synthesis of phosphorylsuccinates and triphenylphosphanylidenesuccinates containing a thioamido group

Abstract

Stable substituted dialkyl phosphorylsuccinates were synthesized, as a mixture of two diastereoisomers, in high yields using one-pot reaction of dialkyl acetylenedicarboxylates, trialkyl phosphites, and thioamides in CH₂Cl₂ at room temperature. Using triphenylphosphine instead of phosphites, afforded stabilized triphenylphosphanylidenesuccinates. DFT calculations at B3LYP/6-31?+?G(d) level indicated that among four possible conformational diastereoisomers of dimethyl 2-(dimethoxyphosphoryl)-3-ethanethioamidosuccinate, the (2R,3S) and (2S,3S) diastereomers are the most stable forms.     

3-(Acylamino)-3-amino-2-nitroacrylonitriles from N-Acyl-S-methyl-3,3-diamino-2-nitroacrylthioimidates

Reaction of N-acyl-3,3-diamino-2-nitroacrylthioamides 1 with MeI at room temperature leads to N-acyl-S-methyl-3,3-diamino-2-nitroacrylthioimidates 2 in moderate yields. The latter react with Hg(OAc)₂ in DMF yielding 3-(acylamino)-3-amino-2-nitroacrylonitriles 8 . The structures of 2a and 8a were established by X-ray crystallography.     

Mild and Copper‐Free Stereoselective Cyanation of gem‐Difluoroalkenes by Using Benzyl Nitrile as a Cyanating Reagent

A novel copper‐free highly stereoselective cyanation of gem‐difluoroalkenes by using benzyl nitrile as a cyanating reagent with the assistance of tBuOLi under air atmosphere at room temperature was developed. A variety of versatile fluorinated alkenyl nitriles were obtained. The proposed mechanism involved the C?H bond oxidation, C?CN bond cleavage, and then nucleophilic vinylic substitution (S_NV).     

Room‐temperature processing of π‐conjugated oligomers into uniaxially oriented monodomain films on coumarin‐based photoalignment layers

Photoalignment layers comprising Polymer 1 were prepared using linearly polarized UV‐irradiation for chloroform‐vapor annealing of π‐conjugated oligomer films, both processes conducted at room temperature. The resultant uniaxially oriented monodomain films exhibited S = 0.74 (at P_r = 0.90) and 0.82 (at P_r = 0.95) in OF and OF2T films, respectively, apparently limited by film dewetting in comparison to S = 0.82 ± 0.01 from thermal annealing on rubbed polyimide alignment and Polymer 1 photoalignment layers. The time to arrive at maximum S values varied from 5–10 s to 6–8 min on rubbed polyimide alignment layers and Polymer 1 photoalignment layer, respectively, because of favorable π–π interactions enhanced by rubbing. In contrast, PF2T could not be oriented on either type of alignment layers after annealing under saturated chloroform vapor up to 14 h. Annealing of an OF2T film under saturated chlorobenzene vapor at room temperature permitted lyotropic nematic mesomorphism to be observed in situ, which is equivalent to thermotropic nematic mesomorphism as the driving force behind thermal annealing. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Enantioselektive Katalysen. 155 [1] (Cymol)Ruthenium‐Halbsandwich‐Komplexe mit Pyrroloxazolin‐Liganden — Synthese,Stereochemie, Katalyse

Asymmetric Catalysis. 155 [1] (Cymene)Ruthenium Halfsandwich Complexes with Pyrroleoxazoline Ligands — Synthesis, Stereochemistry, Catalysis The (cymene)ruthenium halfsandwich complexes K1 and K2 with chiral pyrroleoxazoline ligands were synthesized and characterized. The complexes form diastereomers, which only differ in the metal configuration. Complex K1 crystallized as the pure diastereomer S_Ru, S_C4, R_C5. In solution epimerization S_Ru, S_C4, R_C5 ? R_Ru, S_C4, R_C5 occurred via change of the configuration at the ruthenium atom. The half‐life for the first‐order reaction at 0.4 °C in CD₂Cl₂ was 50.6 min. Thus, the two diastereomers equilibrate at room temperature. The equilibrium mixtures of K1 und K2 were used as catalysts for the transfer hydrogenation of acetophenone and for the Diels‐Alder reaction of cyclopentadiene with methacrolein. Enantiomeric excesses of up to 60 % ee were achieved.     

Hysteretic Spin Crossover above Room Temperature and Magnetic Coupling in Trinuclear Transition‐Metal Complexes with Anionic 1,2,4‐Triazole Ligands

The reaction of 4‐(1,2,4‐triazol‐4‐yl)ethanesulfonate ( L ) with Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺, and Fe²⁺ gave a series of analogous neutral trinuclear complexes with the formula [M₃(μ‐ L )₆(H₂O)₆] ( 1 – 5 ). These compounds were characterized by single‐crystal X‐ray diffraction, thermogravimetry, and elemental analysis. The magnetic properties of compounds 2 – 5 were studied. Complexes 2 – 4 show weak antiferromagnetic superexchange, with J values of ?0.33 ( 2 ), ?9.56 ( 3 ), and ?4.50 cm^?1 ( 4 ) (exchange Hamiltonian H=?2 J (S₁S₂+S₂S₃)). Compound 5 shows two additional crystallographic phases ( 5 b and 5 c ) that can be obtained by dehydration and/or thermal treatment. These three phases exhibit distinct magnetic behavior. The Fe²⁺ centers in 5 are in high‐spin (HS) configuration at room temperature, with the central one exhibiting a non‐cooperative gradual spin transition below 250 K with T_1/2=150 K. In 5 b , the central Fe²⁺ stays in its low‐spin (LS) state at room temperature, and cooperative spin transition occurs at higher temperatures and with the appearance of memory effect (T_1/2↑=357 K and T_1/2↓=343 K). In the case of 5 c , all iron centers remain in their HS configuration down to very low temperatures, with weak antiferromagnetic coupling (J=?1.16 cm^?1). Compound 5 b exhibits spin transition with memory effect at the highest temperature reported, which matches the remarkable features of coordination polymers.     

Preparation of planar‐chiral multidonor phosphanylferrocene carboxamides and their application as ligands for palladium‐catalysed asymmetric allylic alkylation

Amide coupling of (S_p)‐2‐(diphenylphosphanyl)ferrocene‐1‐carboxylic acid with appropriate terminal amines mediated by 1‐hydroxybenzotriazole and a carbodiimide affords multi‐donor amides terminally functionalized with planar‐chiral (S_p)‐2‐(diphenylphosphanyl)ferrocen‐1‐yl moieties in good to excellent yields. Palladium catalysts based on these ligands efficiently promote asymmetric allylic alkylation of 1,3‐diphenylallyl acetate with in situ generated dimethyl malonate anion to give the C‐alkylated product with ees up to 93% at room temperature. Copyright © 2010 John Wiley & Sons, Ltd.     

Multiple-State Emissions from Neat,Single-Component Molecular Solids: Suppression of Kasha's Rule

Three rigid and structurally simple heterocyclic stilbene derivatives, (E)-3H,3′H-[1,1′-biisobenzofuranylidene]-3,3′-dione, (E)-3-(3-oxobenzo[c] thiophen-1(3H)-ylidene)isobenzofuran-1(3H)-one, and (E)-3H,3′H-[1,1′-bibenzo[c] thiophenylidene]-3,3′-dione, are found to fluoresce in their neat solid phases, from upper (S₂) and lowest (S₁) singlet excited states, even at room temperature in air. Photophysical studies, single-crystal structures, and theoretical calculations indicate that large energy gaps between S₂ and S₁ states (T₂ and T₁ states) as well as an abundance of intra and intermolecular hydrogen bonds suppress internal conversions of the upper excited states in the solids and make possible the fluorescence from S₂ excited states (phosphorescence from T₂ excited states). These results, including unprecedented fluorescence quantum yields (2.3–9.6 %) from the S₂ states in the neat solids, establish a unique molecular skeleton for achieving multi-colored emissions from upper excited states by “suppressing” Kasha's rule.     

Multiple‐State Emissions from Neat,Single‐Component Molecular Solids: Suppression of Kasha's Rule

Three rigid and structurally simple heterocyclic stilbene derivatives, (E)‐3H,3′H‐[1,1′‐biisobenzofuranylidene]‐3,3′‐dione, (E)‐3‐(3‐oxobenzo[c] thiophen‐1(3H)‐ylidene)isobenzofuran‐1(3H)‐one, and (E)‐3H,3′H‐[1,1′‐bibenzo[c] thiophenylidene]‐3,3′‐dione, are found to fluoresce in their neat solid phases, from upper (S₂) and lowest (S₁) singlet excited states, even at room temperature in air. Photophysical studies, single‐crystal structures, and theoretical calculations indicate that large energy gaps between S₂ and S₁ states (T₂ and T₁ states) as well as an abundance of intra and intermolecular hydrogen bonds suppress internal conversions of the upper excited states in the solids and make possible the fluorescence from S₂ excited states (phosphorescence from T₂ excited states). These results, including unprecedented fluorescence quantum yields (2.3–9.6 %) from the S₂ states in the neat solids, establish a unique molecular skeleton for achieving multi‐colored emissions from upper excited states by “suppressing” Kasha's rule.     

A Rapid and Efficient Stereoselective Synthesis of (Z)‐ and (E)‐Allyl Bromides from Baylis–Hillman Adducts Using Bromo(dimethyl)sulfonium Bromide

Treatment of Baylis–Hillman adducts 1 with bromo(dimethyl)sulfonium bromide, Br(Me₂)S⁺Br^?, in MeCN was found to stereoselectively afford (Z)‐ and (E)‐allyl bromides 2 . The reaction is rapid at room temperature, high‐yielding, and highly stereoselective.     

Temperaturabhängiger Circulardichroismus von (3S, 3′R)- und (3S, 3′ S)-Adonixanthin

The temperature dependent CD. spectra of (3S, 3′R)- and (3S, 3′S)-adonixanthin are compared with those of (3R, 3′R)-zeaxanthin ( 1 ) and (3S, 3′S)-astaxanthin ( 2 ). The room temperature spectra of 1 and 2 are quite similar. On cooling to ?180° the CD. of 1 simply intensifies, the CD. of 2 changes sign and becomes also very intense. The room-temperature CD. of (3S, 3′R)-adonixanthin ( 3 ) resembles closely those of 1 and 2 at room temperature. On cooling, however, it becomes weak and changes strongly its shape. With (3S, 3′S)-adonixanthin ( 4 ) it is the low-temperature spectrum which resembles that of 2 at low temperature, whereas the room-temperature spectrum is weak and quite different in shape. These observations can be explained with temperature dependent equilibria where the end groups are twisted out of the plain of the chain thereby conferring chirality to the conjugated system.     

Enhanced Nanostructure Dynamics on Au(111) with Adsorbed Sulfur due to Au−S Complex Formation

Chemisorbed species can enhance the fluxional dynamics of nanostructured metal surfaces which has implications for applications such as catalysis. Scanning tunneling microscopy studies at room temperature reveal that the presence of adsorbed sulfur (S) greatly enhances the decay rate of 2D Au islands in the vicinity of extended step edges on Au(111). This enhancement is already significant at S coverages, θ_S, of a few hundredths of a monolayer (ML), and is most pronounced for 0.1–0.3 ML where the decay rate is increased by a factor of around 30. For θ_S close to saturation at about 0.6 ML, sulfur induces pitting and reconstruction of the entire surface, and Au islands are stabilized. Enhanced coarsening at lower θ_S is attributed to the formation and diffusion across terraces of Au−S complexes, particularly AuS₂ and Au₄S₄, with some lesser contribution from Au₃S₄. This picture is supported by density functional theory analysis of complex formation energies and diffusion barriers.     

Synthese und Kristallstrukturen der quaternären Chalkogenidchloride AgBi2S3Cl und AgBi2Se3Cl

Synthesis and Crystal Structures of the Quaternary Chalcogenide Chlorides AgBi₂S₃Cl and AgBi₂Se₃Cl Grey crystals of AgBi₂S₃Cl and AgBi₂Se₃Cl were synthesized from AgCl and Bi₂S₃ or Bi₂Se₃by cooling stoichiometric melts from 790 K to room temperature. X‐ray diffraction on powders and single‐crystals revealed that the compounds crystallize isostructural with space group type P 2₁/m. In the crystal structure of AgBi₂S₃Cl the bismuth(III) cations have a capped trigonal prismatic coordination of sulfide and chloride ions. The prisms constitute a three‐dimensional framework by sharing common edges and faces. Silver(I) cations, which have a distorted octahedral coordination of sulfide ions, fill linear channels. Parallels to the crystal structures of Cu₃Bi₂S₄Cl and Pr₂Br₅ can be seen.     

Evidence of distinct water species in cellulosic environments from broad-line NMR

Broad-line NMR measurements were made on water in cellulosic samples. The spectra for oriented rayon at 65% relative humidity and room temperature consisted of a visually apparent doublet (S_D) and a narrow singlet (S_N) which was shifted upfield about 7 ppm from the center of the doublet. The doublet separation varied as A(3 cos²θ—1), where θ is the angle between the fiber axis and the magnetic field; the maximum doublet separation was 350 mG at both 15.1 and 56.4 MHz, indicating the doublet is dipolar in origin. The peak-to-peak linewidth of the narrow singlet was orientation and field dependent. The upfield shift of the narrow singlet from the doublet center was field dependent. Spectra for vacuum-treated rayon consisted of only the narrow singlet, which was orientation dependent. The doublet separation decreases with increasing moisture content and is essentially zero for oriented rayon samples at 100% relative humidity; the resulting spectra due to the collapsed doublet and S_N singlet was an asymmetric line. Temperature-dependent measurements were made on oriented rayon at 65% relative humidity with the fiber axis parallel to the magnetic field; when the temperature was increased from about 0° the peak-to-peak linewidth of the doublet halves and the doublet separation decreased. As the temperature was increased from about 30 to about 65°C, a previously unobserved singlet (S_E) became visible. The relative amplitudes of the three lines varied with temperature as follows: The S_E singlet increased, the S_D doublet decreased, and the amplitude of the S_N singlet remained constant. Measurements using oriented cotton samples and randomly packed rayon samples indicated that the NMR line shape of the water spectra depends upon the physical properties of the macromolecular substrate. The doublet component of the spectra is attributed to a water species (S_D) which is highly bonded to the macromolecular substrate. The S_E singlet is attributed to an energetic water species (S_E) which is rapidly tumbling in the macromolecular environment. The S_N singlet is not due to free water.