脯氨酸类N-酰胺衍生物的核磁共振研究

脯氨酸类衍生物结构独特,鲜有报道利用核磁共振（nuclear magnetic resonance,NMR）技术对氨基酸的手性进行鉴别.利用多种NMR技术:1H NMR、1H-1H同核位移相关谱（1H-1H COSY）、1H-1H质子全相关谱（1H-1H TOCSY）、1H-1H核Overhauser效应谱（1H-1H NOESY）、13C NMR、无畸变的极化转移增强法（DEPT135°）、1H-13C检出1H的异核单量子相干（1H-13C HSQC）和1H-13C检出1H的异核多键相关（1H-13C HMBC）,对脯氨酸类N-酰胺衍生物两种构象异构体的1H和13C NMR进行了全归属,确定了室温下在二甲基亚砜（DMSO）中L型和D型的顺反异构体以相同的比例同时存在.     

Theoretical study of electronic structure of rhodium mononitride and interpretation of experimental spectra

Potential energy curves of 22 electronic states of RhN have been calculated by the complete active space second‐order perturbation theory method. The X¹Σ₀⁺ is assigned as the ground state, and the first excited state a³Π₀+ is 978 cm^?1 higher. The ¹Δ(I) and B¹Σ⁺ states are located at 9521 and 13,046 cm^?1 above the ground state, respectively. The B¹Σ⁺ state should be the excited state located 12,300 cm^?1 above the ground state in the experimental study. Moreover, two excited states, C¹Π and b³Σ⁺, are found 14,963 and 15,082 cm^?1 above the X¹Σ⁺ state, respectively. The transition C¹Π₁–X¹Σ₀⁺ may contribute to the experimentally observed bands headed at 15,071 cm^?1. There are two excited states, D¹Δ and E¹Σ⁺, situate at 20,715 and 23,145 cm^?1 above the X¹Σ⁺ state. The visible bands near 20,000 cm^?1 could be generated by the electronic transitions D¹Δ₂–a³Π₁ and E¹Σ⁺₀–X¹Σ⁺₀ because of the spin–orbit coupling effect. © 2013 Wiley Periodicals, Inc.     

New data on the molecular compounds of stereoisomeric ditertiary glycols of the series 1,4-di-(α-hydroxy-sec-alkyl)-cyclohexanes

Summary 1¹,4¹-Dihydroxy-1¹,4¹-diethyl-1,4-dipropylcyclohexanes, like the previously described 1¹,4¹-dihydroxy-1¹,4¹-dimethyl-1,4-diethylcyclohexanes, give a molecular compound of three molecules of cis- and one molecule of trans-form.     

A Novel Entry into a New Class of Spiro Heterocyclic Framework: A Facile Synthesis of Dispiro[oxindole-1,2,3,4-tetrahydro-naphthalen-1-one]pyrrolidines and Spiro[1,2,3,4-tetrahydro-naphthalen-1-one]pyrrolidines

Abstract

2-Arylidene-1,2,3,4-tetrahydro-naphthalen-1-ones undergo regioselective 1,3-dipolar cycloaddition reaction with the azomethine ylide derived from isatin and sarcosine by decarboxylative route affording a series of 1-N-methyl-spiro[2.3¹]oxindole-spiro[3.2¹¹]1¹¹, 2¹¹,3¹¹,4¹¹, -tetrahydro-naphthalen-1¹¹-one-4-aryl-pyrrolidines. 2-Arylidene-1,2,3,4-tetrahydro-naphthalen-1-ones also undergo cycloaddition reaction with azomethine ylide derived from paraformaldehyde and sarcosine affording a series of 1-N-methyl-spiro[3.2¹]1¹,2¹,3¹,4¹-tetrahydro-naphthalen-1¹-one-4-aryl-pyrrolidines. The structures of the compounds were established by spectroscopic techniques.     

The kinetics and mechanisms of gas phase elimination of primary,secondary, and tertiary 2‐hydroxyalkylbenzenes

2‐Phenylethanol, racemic 1‐phenyl‐2‐propanol, and 2‐methyl‐1‐phenyl‐2‐propanol have been pyrolyzed in a static system over the temperature range 449.3–490.6°C and pressure range 65–198 torr. The decomposition reactions of these alcohols in seasoned vessels are homogeneous, unimolecular, and follow a first‐order rate law. The Arrhenius equations for the overall decomposition and partial rates of products formation were found as follows: for 2‐phenylethanol, overall rate log k₁(s⁻¹)=12.43−228.1 kJ mol⁻¹ (2.303 RT)⁻¹, toluene formation log k₁(s⁻¹)=12.97−249.2 kJ mol⁻¹ (2.303 RT)⁻¹, styrene formation log k₁(s⁻¹)=12.40−229.2 kJ mol⁻¹(2.303 RT)⁻¹, ethylbenzene formation log k₁(s⁻¹)=12.96−253.2 kJ mol⁻¹(2.303 RT)⁻¹; for 1‐phenyl‐2‐propanol, overall rate log k₁(s⁻¹)=13.03−233.5 kJ mol⁻¹(2.303 RT)⁻¹, toluene formation log k₁(s⁻¹)=13.04−240.1 kJ mol⁻¹(2.303 RT)⁻¹, unsaturated hydrocarbons+indene formation log k₁(s⁻¹)=12.19−224.3 kJ mol⁻¹(2.303 RT)⁻¹; for 2‐methyl‐1‐phenyl‐2‐propanol, overall rate log k₁(s⁻¹)=12.68−222.1 kJ mol⁻¹(2.303 RT)⁻¹, toluene formation log k₁(s⁻¹)=12.65−222.9 kJ mol⁻¹(2.303 RT)⁻¹, phenylpropenes formation log k₁(s⁻¹)=12.27−226.2 kJ mol⁻¹(2.303 RT)⁻¹. The overall decomposition rates of the 2‐hydroxyalkylbenzenes show a small but significant increase from primary to tertiary alcohol reactant. Two competitive eliminations are shown by each of the substrates: the dehydration process tends to decrease in relative importance from the primary to the tertiary alcohol substrate, while toluene formation increases. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 401–407, 1999     

Time-resolved photoelectron studies of the relaxation of the S1(1E′') excited state of sym-triazine

We present photoelectron spectra of the lowest singlet state (¹E′') of sym-triazine obtained with 2 ns and 5 ps excitation sources. Comparisons of picosecond and nanosecond spectra are made at three wavelengths, corresponding to the 6₀¹, 6₀² and the 6₀¹12₀¹ vibrational levels. The spectra show that rapid (</ 5 ps) relaxation to the lowest triplet state occurs subsequent to singlet excitation. Coupling of S₁ levels to the T₁ manifold is very inhomogeneous with intersystem crossing rates ranging from 10⁷ s⁻¹ to > 10¹¹ s⁻¹. Furthermore, for excitation at the 6₀¹12₀¹ level we find evidence for relaxation to another excited state at rates ⩾ 10¹¹ s⁻¹.     

A Field Effect Transistor Sensitive to the Phenobarbical Anion

Abstract

A field effect transistor sensitive to the phenobarbital anion is described. The response is Nernstian between 10^?1 mol 1^?1 and 10^?4 mol 1^?1 in the absence of added hydroxide, and 10^?1 mol 1^?1 to 10^?3 mol 1^?1 in the presence of added hydroxide. Selectivities over sulphate, chloride, nitrate, hydrogen phosphate have been determined and speed of response and stability are greater than the corresponding coated wire electrode.     

Porphyrins. 18. Synthesis of octapropylporphyrin by the method of monopyrrole cyclotetramerization of 5-carboxy-2-methoxymethyl-3,4-dipropylpyrrole. Investigation of the thermolysis of meso-N-methylformaldimineocta-propylporphyrin

The synthesis of octapropylporphyrin on the basis of 5-carboxy-2-methoxymethyl-3,4-dipropylpyrrole was realized. It was demonstrated that in the thermolysis of meso-N-methylformaldimineoctapropylporphyrin, 3¹,5¹-cyclo-3¹-ethylidene- and 3¹,5¹-cyclo-3¹-ethyl-5¹-(N-methylimine) derivatives are also formed in addition to 3¹,5¹-cyclo-3¹-ethylhectaporphyrin.See [1] for Communication 17.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 922–927, 1984.     

Production of electronically excited NF by the reaction of fluorine atoms with HN3

Electronically excited NF in both the a¹Δ and b ¹Σ⁺ states hasbeen observed from the reaction of fluorine atoms with HN₃. The results suggest that fluorine atoms first abstract the hydrogen atom from HN₃, then react with the remaining N₃ to form NF^≠(a¹Δ). NF^*(b¹Σ⁺) is produced by a subsequent energy pooling reaction between NF^≠(a¹Δ) and vibrationally excited HF. The rate of the F + N₃ reaction is estimated to be ≈ 10¹² and ³ mole^?1 s^?1.     

Complete assignment of NMR data of 22 phenyl‐1H‐pyrazoles' derivatives

Complete assignment of ¹H and ¹³C NMR chemical shifts and J(¹H/¹H and ¹H/¹⁹F) coupling constants for 22 1‐phenyl‐1H‐pyrazoles' derivates were performed using the concerted application of ¹H 1D and ¹H, ¹³C 2D gs‐HSQC and gs‐HMBC experiments. All 1‐phenyl‐1H‐pyrazoles' derivatives were synthesized as described by Finar and co‐workers. The formylated 1‐phenyl‐1H‐pyrazoles' derivatives were performed under Duff's conditions. Copyright © 2011 John Wiley & Sons, Ltd.     

A theoretical investigation of the origins of the green and red spectra of Ca2

The potential energy curves and transition moments of the ground state of Ca₂ and ¹Σ⁺_u states correlating with the ¹S + ¹P and ¹S + ¹D calcium atoms have been calculated. The calculations support the assignment of the observed emission spectra of Ca₂ in the red and in the green to transitions between the ground state and the 1,2¹Σ⁺_u states. Predissociation of the 1¹Σ⁺_u state is also shown to be possible from an interaction with the 1³Π_u state.     

Fe3+和Fe2+对原代培养的成骨细胞增殖、分化和矿化功能的影响

采用噻唑蓝(MTT)法、碱性磷酸酶(ALP)比活性测定、油红O染色和茜素红染色及定量分析,研究了不同浓度的Fe3+和Fe2+对原代培养的成骨细胞增殖、分化及矿化功能的影响.结果表明:浓度为1×10-9～1×10-4 mol·L-1的Fe3+和Fe2+促进成骨细胞增殖,但是在较高浓度1×10-3 mol·L-1时,它们则抑制成骨细胞增殖.与成骨细胞作用48 h,浓度为1×10-8～1×10-4 mol·L-1的Fe3+和Fe2+抑制其分化,但在较低的浓度1×10-9 mol·L-1时则对其分化没有影响:进一步延长作用时间为72 h,Fe3+对成骨细胞分化没有影响,除1×10-6mol·L-1浓度的Fe2+促进成骨细胞分化外,其他浓度的Fe2+则抑制其分化;测试浓度下的Fe3+对成骨细胞向脂肪细胞的横向分化表现为抑制或没有影响,而Fe2+的影响则依赖于浓度和作用时间.在1×10-8～1×10-5mol·L-1浓度范围内,Fe3+和Fe2+对矿化结节的影响表现出相反的效应.在较高浓度(1×10-4mol·L-1)下,它们促进矿化节结的形成,而在较低浓度(1×10-9mol·L-1)下,Fe3+抑制矿化节结的形成,Fe2+则没有影响.结果提示:浓度.作用时间和铁离子的价态都是影响Fe3+和Fe2+生物效应(从毒性到活性,从损伤到保护,从上调到下调)转变的关键因素.     

Threshold energies for production of CH2(3B1) and CH2(1A1) from ketene photolysis. The CH2(3B1) ↔ CH2(1A1) energy splitting

By measuring the relative CO quantum yields from ketene photolysis as a function of photolysis wavelength we have determined the threshold energy at 25° for CH₂CO(¹A₁) → CH₂(³B₁) + CO(¹Σ⁺) to be 75.7 ± 1.0 kcal/mole. This corresponds to a value of 90.7 ± 1.0 kcal/mole for ΔH_f298⁰[CH₂(³B₁)]. By measuring the relative ratio of CH₂(¹A₁)/CH₂(³B₁) from ketene photolysis as a function of photolysis wavelength we have determined the threshold energy at 25°C for CH₂CO(¹A₁) → CH₂(¹A₁) + CO(¹Σ⁺) to be 84.0 ± 0.6 kcal/mole. This corresponds to a value of 99.0 ± 0.6 kcal/mole for ΔH_f298⁰[CH₂(¹A₁)]. Thus a value for the CH₂(³B₁) ? CH₂(¹A₁) energy splitting of 8.3 ± 1 kcal/mole is determined, which agrees with three other recent independent experimental estimates and the most recent quantum theoretical calculations.     

Ab initio potential energy surfaces for BH+2

Preliminary ab initio calculations for the BH⁺₂ potential surface are presented. The reaction B⁺¹S) + H₂ → BH⁺ (B₂ (B²σ⁺) + H is shown to be most likely to occur for C_2v and near C_2v geometrics where there are avoided crossings between the 1 ¹A₁ and 2 ¹A₁ surfaces and between the 2 ¹A₁ and 3 ¹A₁ surfaces which should facilitate non-adiabatic transitions. Bent geometries are alos preferred for the reaction B⁺(¹S) + H₂ → BH⁺(A²π) + H for which there are avoided crossings in C₂ sysmmetry between surfaces correlating with 1 ¹A₁ and 1 ¹B₂ surfaces.     

Absorption,fluorescence and phosphorescence spectra of the singlet and triplet states of s-tetrazine in the crystal and in mixed crystals at low temperatures

The electronic absorption, fluorescence and phosphorescence spectra of s-tetrazine at low temperatures (4.2-1.5 K) are reported and analyzed in the neat crystal and in several mixed crystals. The ³B_3u-¹A_g (nπ^*) origin is at 18414 ± 5 cm^?1 for neat tetrazine. In the mixed crystal several sites identified. The lowest energy origin is at 17453 cm^?1 for tetrazine in pyrazine; 17 701 cm^?1 in pyrimidine; and 17 676 cm^?1 in pyridazine. The ^eB_3u-¹A_g (nπ^*) origin is at 14 096 ± 2 cm^?1 for the neat crystal. The phosphorescence lifetime of neat tetrazine is measured to be 96.8 ± 2.1 μs at 4.2 and 1.8 K. All the spectra are predominately composed of members of progressions in a single totally symmetric mode (ν_6a) built upon site origins and vibrational fundamentals. The ν_6a interval is: 743 (¹A_g), 715 (³B_3u), and 709 cm^?1 (¹B_3u) in the neat tetrazine crystal; 732 (¹A_g) and 705 cm^?1 (¹B_3u in pyrazine host, 737 (¹A_g) and 701 cm^?1 (¹B_3u) in pyrimidine host, and 732 (¹A_g) and 703 cm^?1 (¹B_3u) in pyridazine host mixed crystals. All emission spectra may be analyzed by Oi → (ν″_6a)^o_n (i), i indicating the observed s     

Photodissociation Spectra of OCS+ via B2∑+←X2∏ Transitions

In the wavelength range of 231-275 nm, we have studied the mass-resolved dissociation spectra of OCS⁺ via B²∑⁺←X²∏_3/2(000) and B²∑⁺←X²∏_1/2(000, 001) transitions by preparing OCS⁺ ions in the well-defined spin-orbit states. The spectroscopic constants ofυ1(CS stretch)=828.9 (810.4) cm^-1, υ2(bend)=491.3 cm^-1 and υ3(CO stretch)=1887.2 cm^-1 for OCS⁺(B²∑⁺) are deduced. The observed dependence of the υ2(bend) mode excitation of B²∑⁺ on the spin-orbit splitting of X²∏(Ω=1/2, 3/2) in the B²∑⁺←X²∏ transition can be attributed to the K coupling between the (000)²∏_1/2 and (010)²∑⁺_1/2 vibronic levels of X²∏ state, which makes the B²∑⁺(010)←X²∏_1/2(000) transition possible.     

The photophysics of trans-stilbene

The fluorescence lifetime of trans-stilbene in dilute methylcyclohexane/iso-hexane solution has been measured and the mean S₁ radiative (k_F), radiationless (k_I) and cis-isomerization (k_C) rate parameters have been determined from ?90 to 60°C. S_i consists of a fluorescent trans (¹B_u^*) state (k_F⁰ = 6.0 × 10⁸ s^?1) which undergoes reversible thermal-activated rotational internal conversion (ΔH = 1.75 kcal mole^?1, ΔS = 10.6 cal deg^?1 mole^?1) to a non-fluorescent perp (¹A_g^*) state. p(¹A_g^*) lies 610 cm^?1 above t (¹B_u^*) with an intermediate S₁ potential maximum. p(¹A_g^*) undergoes internal conversion(k_I.^∞ = 5.8 × 10⁸ s^?1) to p (¹A_g) leading to cis-isomerization. This is the main isomerization channel over the whole temperature range.     

Study of singlet-triplet coupling in glyoxal by level anticrossing spectroscopy. VI. Vibrational density and statistics of matrix elements versus energy

By laser excitation of the rotationless level (J = 0) of ten vibrational levels of the S₁ (A_u) state (0⁰, 7², 5¹, 8¹, 6¹7¹, 4¹, 8¹7², 2¹, 8¹4¹ and 2¹7²) of supersonic jet cooled glyoxal, we have obtained S₁-T₁ anticrossing spectra using the homogeneous, high magnetic field (0–8 T) of a Bitter coil. As explained previously, V_st is readily obtained from the width of an anticrossing. As triplet vibrational energy increases from 2776 (0⁰ of S₁) to 4636 cm⁻¹ (2¹7² of S₁), the number of anticrossings increases from 38 (0⁰) to 871 (2¹7²). The anticrossing density is related to the vibrational density of T₁. The V_st histrograms obtained for each vibrational level are very similar: p(V_st) ∝ V^−1−α_st with 0.4 ⩽ α ⩽ 0.7. The more significant and surprising result is that <V_st > is independent of vibrational energy, even though the corresponding vibrational overlaps predicted a decrease in <V_st >, of at least two orders of magnitude between 0⁰ and 2¹7². From V_st statistics we determine ϱ<V_st > and ϱ<V²_st > which are the dominant factors for ISC (intersystem crossing). We predict that strong S-T mixing should occur above 6900 ± 500 cm⁻¹.     

Berechnung der Röntgen- und Auger-Linien des Methans mit Hilfe des Pseudo-Neon-Modells

Zusammenfassung Mit Hilfe des Pseudoneonmodells wurden die Energien der aus den folgenden Konfigurationen hervorgehenden Terme bzw. Mittelwerte dieser Energien für das Methanmolekül bestimmt: [(1s)² (2s)² (2p)⁶], [(1s)¹ (2s)² (2p)⁶], [(1s)¹ (2s)² (2p)⁶ (3p)¹], [(1s)¹ (2s)² (2p)⁶ (4p)¹], [(1s)¹ (2s)² (2p)⁶ (3d)¹], [(1s)² (2s)¹ (2p)⁵], [(1s)² (2s)² (2p)⁴] und [(1s)² (2s)⁰ (2p)⁶].Die Energien wurden mit Hilfe der Slater-Condonschen Regeln analytisch berechnet und dann mit einer elektronischen Rechenmaschine (Zuse 23) minimisiert.Aus den erhaltenen Energiewerten wurde die Lage der Röntgen- und Auger-Linien des Methans berechnet. Die von Mehlhorn [8] gemessenen Auger-Elektronenenergien konnten zugeordnet werden.Die Rechenergebnisse stimmen mit den von Chun aus Röntgenabsorptionsmessungen ermittelten experimentellen Werten befriedigend überein.

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The pseudo neon model is used to calculate the energies of the levels deriving from the following configurations (or their mean values) of the methane molecule: [(1s)² (2s)² (2p)⁶], [(1s)¹(2s)²(2p)⁶], [(1s)¹(2s)²(2p)⁶(3p)¹], [(1s)¹ (2s)² (2p)⁶ (4p)¹], [(1s)¹ (2s)² (2p)⁶ (3d)¹], [(1s)² (2s)¹ (2p)⁵], [(1s)² (2s)² (2p)⁴] and [(1s)² (2s)² (2p)⁶].The energy expressions are given by the Slater-Condon rules; the minimization is done with a digital computer (Zuse 23). Prom the energy values obtained the X-ray and Auger lines of methane are calculated. An interpretation of the experimental Auger electron energies of Mehlhorn [8] is made.Calculated and measured (by Chun) values are in satisfactory agreement with each other.

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Résumé A l'aide du modèle du pseudo-atome de néon, les énergies des niveaux dérivant des configurations suivantes (ou leurs moyens) ont été calculées: [(1s)² (2s)² (2p)⁶], [(1s)¹ (2s)² (2p)⁶], [(1s)¹(2s)²(2p)⁶(3p)¹], [(1s)¹(2s)²(2p)⁶(4p)¹], [(1s)¹ (2s)² (2p)⁶ (3d)¹], [(1s)² (2s)¹ (2p)⁵], [(1s)² (2s)² (2p)⁴] et [(1s)² (2s)⁰ (2p)⁶].Les énergies sont données par les règles de Slater et Condon et minimisées à l'aide d'une machine à calculer électronique (Zuse 23).On en dérive les spectres X et d'Auger du méthane. Nous pouvions interpréter les énergies des électrons Auger mesurées par Mehlhorn [8]. Les calculs s'accordent assez bien aux valeurs expérimentales de Chun.

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Auszug aus der Dissertation von T. K. Ha, Frankfurt am Main, 1963.