Freezing-point of mixtures of H 2 16 O and H 2 18 O

Freezing-point depression of mixtures of H ₂ ¹⁶ O and H ₂ ¹⁸ O were measured. The results showed that the freezing point of the mixture rose linearly with an increase in the molal concentration of H ₂ ¹⁸ O. The results suggested the formation of a solid solution of H ₂ ¹⁶ O and H ₂ ¹⁸ O by freezing, similar to that formed by H ₂ O–D ₂ O, and that H ₂ ¹⁸ O behaves as a different molecule than H ₂ ¹⁶ O.     

Total synthesis of Δ-PGJ2, 15-deoxy-Δ-PGJ2, and related compounds

A key cyclopentenone possessing the α-chain was synthesized from TBS ether of 4-cyclopentene-1,3-diol monoacetate, and submitted to aldol reaction at the α^′-position with the ω-chain aldehydes followed by dehydration to produce the title compounds. In a similar manner, 5-dehydro compounds (acetylene analogues) were synthesized successfully. In addition, palladium-catalyzed reaction of 4-cyclopentene-1,3-diol monoacetate with methyl malonate, the first step of the synthesis, was improved to afford the product in high yield by using t-BuOK or LDA in place of NaH.     

The Synthesis of 13C9-15N-Labeled 3,5-Diiodothyronine and Thyroxine

Thyroid hormones undergo extensive metabolism to regulate hormone activity. A labeled thyroid hormone would be useful to track hormone metabolism through various pathways. While radiolabeled thyroid hormones have been synthesized and used for in vivo studies, a stable isotope labeled form of thyroid hormone is required for studying thyroid hormone metabolism by LC-MS/MS, an analytical technique that has certain advantages without the complications of radioactivity. Here we report the synthesis of ¹³C₉-¹⁵N-T₂ and ¹³C₉-¹⁵N-T₄, two labeled thyroid hormone derivatives suitable for in vivo LC-MS/MS studies.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Ab initio investigations of the bound rovibrational levels of NeH 2 + , NeHD+, and NeD 2 +

Summary Bound rovibrational levels have been calculated for NeH ₂ ⁺ , NeHD⁺, and NeD ₂ ⁺ using three recent fits to an accurateab initio PES. The NeH ₂ ⁺ molecule behaves essentially as a linear molecule, the predicted rotational constant is 2.57 cm^–1. The fundamental frequencies are 811, 1189, and 1748 cm^–1 for the Ne-H ₂ ⁺ stretch, the Ne-H ₂ ⁺ bend and H ₂ ⁺ stretching modes, respectively.Dedicated to the 60th birthday of Prof. W. Kutzelnigg, Bochum     

ZUR KENNTNIS DES NATRIUMDIPHENYLPHOSPHINOFORMIATS Ph2PCOONa1

Abstract

Ph ₂ PCOONa 2, hergestellt dutch Reaktion von Ph₂PNa mit CO₂, wird in protischen Medien rasch unter Bildung von Ph₂PH and CO₂ hydrolysiert. Die Hydrolyse verlauft in Natronlauge sehr viel langsamer and es bilden sich zusätzlich geringe Mengen Ph₂P(O)O^? und HCOO^?, Aus 2 and stöchiometrischen Mengen RI bilden sich tertiäre Phosphine Ph₂PR (R[dbnd]Me, Et) während mit überschüssigem MeI das Phosphoniumsalz [Ph₂PMe₂]I erhalten wird. Ph₂PCOOMe, Ph₂PCOOSiMe₃ bzw. Ph₂PCSSNa wurden durch Umsetzung von 2 mit (MeO)₂SO₂, Me₃SiCl bzw. CS₂ synthetisiert. Ph₂P(O)ONa and Ph₂P(S)SNa entstanden bei der Reaktion von 2 mit O₂ oder S₈ in Benzol.

Concerning Sodiumdiphenylphosphinoformiate Ph2PCOONa¹.

Ph₂PCOONa 2, prepared from Ph₂PNa and CO₂, is readily hydrolyzed in protic media with formation of Ph ₂ PH and CO₂. Hydrolysis is much slower in NaOH and small quantities of Ph₂P(O)O^? and HCOO^? are additionally formed. Reactions of 2 with RI in stoichiometrical amounts gave tertiary phosphines Ph₂PR (R[dbnd]Me, Et) while the phosphonium compound [Ph₂PMe₂]I resulted from 2 and MeI in excess. Ph₂PCOOMe, Ph₂PCOOSiMe₃ or Ph₂PCSSNa were obtained from 2 and (MeO)₂SO₂, Me₃SiCl or CS₂. Ph₂P(O)ONa and Ph₂P(S)SNa were isolated when 2 was reacted with O₂ or S₈ in benzene.     

Spectres RMN-13C de Quelques Medicaments a Action Parasymatholytique Peripferique Derives du 1,3-Propanol

Abstract

Les spectres RMN-¹³ C de quelques dérivés du propanol substitué en 1,3 ont été étudiés. Une attribution des signaux est propasée.

Carbon-13 nuclear magnetic resonance spectra of some substituted 1, 3-propanols have been recorded and fully assigned.     

Peculiarity of the Dickinson H 2 + wave function

According to the zero potential energy criterion proposed recently, the Dickinson wave function for the 2p_u state of the H ₂ ⁺ system is an unexpectedly poor approximation so long as the known parameters are employed. We re-examine the optimum parameters for the Dickinson wave function and find that there exist two sets of optimum parameters with different wave function characteristics. The corresponding energy curves cross at R= 1.91 a.u., though the difference is very small. We suggest that a new set of optimum parameters with slightly higher energy for R>1.91 a.u. is more acceptable physically than the previously reported set.     

复合催化剂上CO2加氢合成C2烃类

介绍了由CO₂+H₂合成C2⁺烃的几种复合催化剂体系的研究进展，比较和评价了复合催化剂体系的活性和选择性及对C2⁺烃类生成的影响。着重于复合催化剂体系对C4⁺烃的生成及产物分布的影响并简述反应机理。     

Ab initio calculations on NO2 and NO 2 − : Optimization of diffuse Gaussian exponents

Ab initio calculations of NO₂ and NO ₂ ⁻ , using a Dunning [4s3p] basis augmented by 1 component diffuses andp functions were carried out. The SCF energies of NO₂ and NO_2/− (ground states) as a function of O _s , O _p , N _s , and N _p diffuse function exponents are given and discussed. The curves show some unexpected features which make the optimization of the diffuse function exponents problematic. The SCF vertical electron detachment energy for NO ₂ ⁻ as a function of the diffuse O _s , O _p , N _s , and N _p exponents is then discussed. Except for the case of O _p , the detachment energy is essentially independent of the O _s , N _s , and N _p exponents. Finally, results of SCF and MCSCF/CI calculations of the electron affinity of NO₂ are given and compared with experiment. Work performed under the auspices of the Division of Basic Energy Sciences of the U.S. Department of Energy. By acceptance of this article, the publisher and/or recipient acknowledges the U.S. Government's right to retain a nonexclusive, royalty-free license in and to any copyright covering this paper.     

Host-Guest Interactions between Calixarenes and Cp(2)NbCl(2)

The possible inclusion complexes of Cp₂NbCl₂ into calixarenes hosts have been investigated. The existence of a true inclusion complex in the solid state was confirmed by a combination of NMR, ab-initio calculations, thermogravimetric analysis, FTIR, Raman and PXRD. Ab-initio calculations, ¹H NMR solution and solid state ¹³C CP-MAS NMR results demonstrated that p-sulfonic calix[6]arene does form an inclusion complex with Cp₂NbCl₂. Raman spectroscopy showed, for the inclusion compound of p-sulfonic calix[6]arene-Cp₂NbCl₂, a band between 500 and 850 cm⁻¹ characteristic of Nb-O vibration. This result suggests that Nb(V) may engage in coordination with the oxygen of the sulfonate group, as part of the host-guest interaction. However, it is important to mention that the niobocene dichloride (Cp₂NbCl₂) dissolves in water and undergoes oxidation and hydrolysis processes to yield Cp₂NbCl₂(OH) species. For that reason this band does not exclude that the Nb-O band belongs to Cp₂NbCl₂(OH). Solid State ¹³C CP-MAS NMR and solution ¹H NMR spectroscopies together with ab-initio results showed that Cp₂NbCl₂ is included in the p-sulfonic calix[6]arene cavity, with both Cp rings inside the cavity. In contrast, the solution ¹H NMR results demonstrated that calix[6]arene does not form inclusion complex with Cp₂NbCl₂ in CDCl₃ solution. Cp₂NbCl₂ is not included in the calix[6]arene cavity, possibly due to the lack of sulfonate heads which promote Nb-O interactions and assist the inclusion of Cp₂NbCl₂ into the cavity.     

A Thermodynamic, 13C NMR,and 17O NMR Study of Isomeric 4,7-Dihydro-1,3-dioxepins and 4,5-Dihydro-1,3-dioxepins

The relative thermodynamic stabilities of 4,7-dihydro-1,3-dioxepin (4,6-dioxacycloheptene, 1a) and 4,5-dihydro-1,3-dioxepin (3,5-dioxacycloheptene, 1b), and of a number of their 2-substituted derivatives, have been determined by base-catalyzed chemical equilibration in DMSO solution. Without exception, the 4,5-dihydro isomer is the dominating species at thermodynamic equilibrium. The relative stability of the b form is promoted by the presence of a single alkyl group on C-2, whereas two alkyl groups on C-2 have an opposite effect. In general, the thermodynamic parameters H _m and _Sm , of isomerization vary unexpectedly with the pattern of substitution at C-2. These trends appear to be derived from significant substituent-induced conformational changes in the b isomer, as suggested by ¹³C and ¹⁷O NMR chemical shift data.     

Study of the vibrational spectra of SO2, H2O and D2O using the U(4) algebraic model

Using the U(4) algebraic model, in this work we report a study of the vibrational spectra of SO₂, H₂0¹⁸ and D₂O¹⁶. The inclusion of intermode couplings in algebraic models has been stated to give a deep insight into detailed spectroscopy for these bent XY₂ molecules. Improved set of algebraic parameters has been reported to provide improved RMS deviations for these molecules.     

Theoretical rotational-vibrational spectra of theX 3 B 1,a 1 A 1 andb 1 B 1 states of NH 2 +

Summary The three-dimensional potential energy functions have been calculated from highly correlated multireference configuration interaction electronic wavefunctions for theX ³ B ₁,a ¹ A ₁, andb ¹ B ₁ states of the NH ₂ ⁺ ion. For the quasi-linear electronic ground state this information and the electric dipole moment functions have been used to calculate spectroscopic constants, line intensities and rotationally resolved absorption spectra. For thea ¹ A ₁-b ¹ B ₁ bent/quasi-linear Renner-Teller system ro-vibronic energy levels have been obtained from a variational approach accounting for anharmonicity, rotation-vibration and electronic angular momenta coupling effects. The vibronic levels are given for energies up to 13 500 cm^–1 for the bending levels and up to 8000 cm^–1 for the stretching and combination levels.Dedicated in the honor of Prof. Werner Kutzelnigg     

The Role and Regulation of Thromboxane A2 Signaling in Cancer-Trojan Horses and Misdirection

Over the last two decades, there has been an increasing awareness of the role of eicosanoids in the development and progression of several types of cancer, including breast, prostate, lung, and colorectal cancers. Several processes involved in cancer development, such as cell growth, migration, and angiogenesis, are regulated by the arachidonic acid derivative thromboxane A₂ (TXA₂). Higher levels of circulating TXA₂ are observed in patients with multiple cancers, and this is accompanied by overexpression of TXA₂ synthase (TBXAS1, TXA₂S) and/or TXA₂ receptors (TBXA2R, TP). Overexpression of TXA₂S or TP in tumor cells is generally associated with poor prognosis, reduced survival, and metastatic disease. However, the role of TXA₂ signaling in the stroma during oncogenesis has been underappreciated. TXA₂ signaling regulates the tumor microenvironment by modulating angiogenic potential, tumor ECM stiffness, and host immune response. Moreover, the by-products of TXA₂S are highly mutagenic and oncogenic, adding to the overall phenotype where TXA₂ synthesis promotes tumor formation at various levels. The stability of synthetic enzymes and receptors in this pathway in most cancers (with few mutations reported) suggests that TXA₂ signaling is a viable target for adjunct therapy in various tumors to reduce immune evasion, primary tumor growth, and metastasis.     

Ca2+-Mg2+-Zn2+体系在水溶性聚磷酸铵溶液中螯合规律的研究

近年来,水溶性聚磷酸铵在液体肥料和复合肥料的领域受到了广泛的关注,并在发达国家中得到了大面积的推广及应用。在pH值为5.5~8.0、温度为278.15 K~323.15 K的条件下,本文采用滴定法研究Ca_²⁺-Mg_²⁺-Zn_²⁺体系在聚磷酸铵溶液中的螯合规律。实验结果表明：相同质量分数的聚磷酸铵溶液对金属离子的螯合量会随着体系中Ca_²⁺、Mg_²⁺、Zn_²⁺的摩尔浓度的变化而变化;随着温度的升高而逐渐降低;随着pH的增加而逐渐增加;随着聚合度的升高而逐渐增加。采用傅里叶红外光谱对聚磷酸铵和A₁B₃C₃体系的螯合物进行表征。     

Ab initio calculations of the rotationally resolved infrared spectrum of KNa 2 +

Summary Ab initio variational calculations were performed on the rotationally resolved infrared spectrum of KNa ₂ ⁺ . A discrete potential energy surface was generated using the configuration interaction ansatz coupled with the frozen core approximation, from which an analytical representation was obtained using a power series expansion employing a Dunham expansion variable. This force field was embedded in an Eckart-Watson rovibrational Hamiltonian, from which eigenfunctions and eigenenergies were calculated. An SCF dipole moment surface was generated and used to calculate absolute line intensities and square dipole matrix elements between the vibrational ground state and the lowest-lying excited states for some of the most intense transitions within the P, Q and R branches.     

Theories of binding in H 2 +

Summary A common, traditional potential energy expression for the theoretical binding energy in the simplest LCAO treatment of H ₂ ⁺ (i.e. using 1s eigenfunctions of the atoms) is derived in the context of Ruedenberg's theory, by virtue of a cancellation between the interference kinetic energy and an identifiable positive part of the interference potential energy arising from charge moving away from dative protons. Thus, although electron sharing raises the total potential energy, its net contribution to the binding energy may be equated to the negative part of the interference potential energy which is due to charge moving towards opposite protons. It is shown that this potential energy expression remains approximately valid when the atomic orbitals are optimally scaled. For contracted orbitals, the cancellation within the interference energy is not exact, and the explanation of contraction through the variation principle is less transparent from a potential energy viewpoint than it is in Ruedenberg's analysis. However, when the orbitals are both contracted and polarised the cancellation is closer to being exact, and the minimisation of the total energy is achieved through competition between the term representing the atomic promotion and deformation energy on the one hand, and the usual potential energy expression on the other.     

Zeta potential and surface free energy changes of solid-supported phospholipid (DPPC) layers caused by the enzyme phospholipase A2 (PLA2)

Stability and wetting properties changes of systems formed of phospholipid DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) layers covering silica particles or glass slides due to the phospholipase A₂ (PLA₂) action were determined by zeta potential measurements and the surface free energy evaluation, respectively. The comparison of the zeta potential and surface free energy, which was evaluated from advancing and receding contact angles via applying models of interfacial interactions, i.e. van Oss et al. (LWAB) and contact angle hysteresis (CAH), was found to be helpful for better understanding the mechanism of PLA₂ action on the lipid layers, what is discussed in the paper.     

MOF-1和Tb@MOF-1荧光探针的设计、 合成及对痕量Cr2O72-、 S2O82-离子的识别

采用5-((4-吡啶基)甲氧基)-异烟酸(H₂PLIA)、1,3,5-三(1-咪唑基)-苯(TIB)合成了金属有机骨架[Cd(PLIA)(TIB)]_n (MOF-1),MOF-1是具有理想一维孔道的二维结构化合物,其一维孔道由柔性三角形PLIA^2-配体和刚性三角形TIB配体间隔形成。利用MOF-1 易掺杂的优势,采用后修饰合成策略制备了Tb@MOF-1。对MOF-1 和Tb@MOF-1 进行了基本表征及荧光探针性能研究。2种探针材料具有相同的结构。MOF-1和Tb@MOF-1分别对水溶液中的Cr₂O₇^2-和S₂O₈^2-离子具有较强荧光识别能力,均有响应时间快,稳定性、选择性、灵敏度高的特点。研究了MOF-1和Tb@MOF-1对Cr₂O₇^2-和S₂O₈^2-的荧光识别机理,其不同可能与Tb³⁺离子掺杂有关。     

2D-NMR: Part VI. 2D-INADEQUATE spectral analysis and crystal structure of tricyclo[7.3.1.02,7]tridecane

2-Hydroxy-13-oxo-tricyclo[7.3.1.0^2,7]tridecane derivatives can be obtained by reaction of cyclohexanone with alcohols under alkaline conditions. The unambiguous assignment of all signals of the¹H-NMR- and¹³C-NMR-spectrum is possible by 2D-¹H-¹³C-shift correlation and 2D-INADEQUATE. Compound1 crystallizes in space group P2₁/n witha=8.518 (1),b=14.789 (2),c=19.321 (2) Å, =94.91 (1)°,Z=8,D _c =1.22 Mg cm^–3. The structure refined toR=0.100 andR _w =0.097 for 1719 observed reflections. Two independent molecules form centrosymmetric hydrogen-bonded dimers.Part V:Haslinger E.,Kalchhau-ser H.,Robien W.,Steindl H., Monatsh. Chem.115, 597 (1984).