The Structure of the “Third‐Generation” Tris(pyrazolyl)borate Caesium Salt p‐BrC6H4TpCs

Slow crystallisation at lowered temperature yielded crystals of the “third‐generation” tris(pyrazolyl)borate transfer agent p‐BrC₆H₄TpCs (Tp′Cs) 1 (triclinic; P$\bar{1}$ ; a = 8.540(4), b = 15.045(6), c = 15.879(7) Å; α = 65.853(8), β = 88.457(8), γ = 75.056(8)°; V = 1791.4(13) Å³; Z = 4). The central caesium ion in 1 interacts with three individual p‐BrC₆H₄Tp ligands in two different chelating fashions.In particular, κ¹‐N‐coordination and η⁵‐π‐coordination of pyrazole moieties as well as η⁶‐π‐coordination of the p‐BrC₆H₄ substituent are observed. Further, comparable coordination of neighbouring caesium ions leads to the formation of polymeric structures connected by two bridging modes.     

Synthesis and characterization of phosphates in molten systems Cs2O-P2O5-CaO-M2O3 (M—Al, Fe, Cr)

The crystallization of complex phosphates from the melts of Cs₂O-P₂O₅-CaO-M^III₂O₃ (M^III—Al, Fe, Cr) systems have been investigated at fixed value Cs/P molar ratios equal to 0.7, 1.0 and 1.3 and Са/Р=0.2 and Ca/М^III=1. The fields of crystallization of CsCaP₃O₉, β-Ca₂P₂O₇, Cs₂CaP₂O₇, Cs₃CaFe(P₂O₇)₂, Ca₉M^III(PO₄)₇ (M^III—Fe, Cr), Cs_0.63Ca_9.63Fe_0.37(PO₄)₇ and CsCa₁₀(PO₄)₇ were determined. Obtained phosphates were investigated using powder X-ray diffraction and FTIR spectroscopy. Novel whitlockite-related phases CsCa₁₀(PO₄)₇ and Cs_0.63Ca_9.63Fe_0.37(PO₄)₇ have been characterized by single crystal X-ray diffraction: space group R3c, a=10.5536(5) and 10.5221(4) Å, с=37.2283(19) and 37.2405(17) Å, respectively.     

强碱胁迫枯草芽孢杆菌芽孢致死的拉曼光谱研究

应用单细胞拉曼分析技术结合PCA方法,以枯草芽孢杆菌芽孢为对象,以强碱为诱导剂实时记录芽孢生理变化过程,探究芽孢在强碱胁迫下的致死机制。实验表明,枯草芽孢杆菌芽孢和其萌发后芽孢在一定范围均有一定的耐受强碱能力,但萌发后芽孢的耐受力明显下降,主要原因是释放了维持其抗性及稳定性的特有Ca2+-DPA的保护;芽胞受强碱胁迫也会有少量Ca2+-DPA释放过程的行为特征,但通过分析所记录的光谱数据结果表明,其释放行为不同于由L-丙氨酸引起的芽孢的正常Ca2+-DPA释放过程。通过PCA比较分析强碱胁迫芽孢和萌发后芽孢Ca2+-DPA释放过程,主要是强碱破坏芽孢膜结构,膜损伤后强碱比较容易进到芽孢内部从而破坏蛋白质的主链结构链及核酸;芽孢膜通道也可能受到强碱的伤害,造成微量Ca2+-DPA的释放。     

Synthesis and crystal structure of three silver indium double phosphates

Three new silver indium double phosphates Ag₃In(PO₄)₂ (I), β-(II) and α-Ag₃In₂(PO₄)₃ (III) were synthesized by solid state method (I and II—700 °C, III—900 °C). Compounds I and II crystallize into a monoclinic system (I—sp. gr. C2/m, Z=2, a=8.7037(1)Å, b=5.4884(1)Å, c=7.3404(1)Å, β=93.897(1)°; II—sp. gr. C2/c, Z=4, a=12.6305(1)Å, b=12.8549(1)Å, c=6.5989(1)Å, β=113.842(1)°), and compound III crystallize into a hexagonal system (sp. gr. R-3c, Z=6, a=8.9943(1)Å, c=22.7134(1)Å). Their crystal structures were determined by the Rietveld analysis (I—R_p=6.47, R_wp=8.54; II—R_p=5.67, R_wp=6.40; III—R_p=7.30, R_wp=9.91). Structure of Ag₃In(PO₄)₂ is related to the sodium chromate structure type and is isotypic to α-Na₃In(PO₄)₂. The polymorphous modifications of β- and α-Ag₃In₂(PO₄)₃ are isostructural to sodium analogs (β- and α-Na₃In₂(PO₄)₃) and are related to alluaudite (II) and NASICON (III) structure types. Compounds I and II are not stable at temperature above 850 °C. Ag₃In(PO₄)₂ is decomposed providing silver orthophosphate Ag₃PO₄ and α-Ag₃In₂(PO₄)₂. β-Ag₃In₂(PO₄)₃ is transformed to α-Ag₃In₂(PO₄)_3.     

Modelling of electrolyte mixtures with application to chemical equilibria in mixtures—prototypes of blood''s plasma and calcification of soft tissues

Modelling of the biologic solutions has a great importance for basic physicochemical backgrounds of the living processes, mechanism of the diseases and drugs action, etc. The modelling of the chemical equilibria in solution that served as a prototype of the blood plasma with application to calcification of the tissues is performed. The concentrations of molecular–ionic forms containing calcium and hydrogen cations and phosphate anions in the range of ionized-calcium and total phosphorus concentrations from 0.5 to 3.0 mM and at the solution pH of 7.1–7.8 were calculated. The activities of the ionized species were described in approach to Debye–Hückel's theory. The full set of the equilibria taking into consideration dissociation of the water, phosphoric acid, formation of both inert and ionic calcium phosphates was considered. The states of calcium hydrophosphate dihydrate CaHPO₄·2H₂O (CHPD), calcium phosphate Ca₃(PO₄)₂ (CP), calcium hydrophosphate-phosphate dihydrate Ca₄H(PO₄)₃·2H₂O (CHPPD) and hydroxyapatite Ca₃OH(PO₄)₃ (HA) with respect to the boundary of the region in which they crystallise were determined. A criterion has been introduced to characterize the degree of salt supersaturation with respect to crystallisation, which is based on the concentration distance between the states of a salt in solution and at the boundary of its crystallisation. This criterion is used to provide a quantitative characteristic of the supersaturation of the phosphates and their tendency to crystallise in blood's plasma. It was established that the most soluble of the phosphates, CaHPO₄·2H₂O, is undersaturated and the other phosphates are supersaturated with respect to crystallisation. Thus, this phosphate does not take part in the calcification, and this is the source for ionized calcium in a blood plasma from the soft tissues. The role of the other phosphates in calcification of the soft tissues is decreased in the series HA>CP>CHPPD. The dependencies of the supersaturation of the solution on the pH and on the concentrations of calcium and phosphorus in a mixture are discussed.     

Thermodynamic Study of the Solid-Liquid Equilibria in the Systems MIPO3-Pr(PO3)3 (MI=Na,Rb, Cs OR Ag)

A previously established equation of a stoichiometric phase liquidus curve was applied to determination of the phase diagrams of the systems M^IPO₃-Pr(PO₃)₃ (with M^I=Na, Rb, Cs or Ag). The temperature, enthalpy and entropy of fusion were calculated for each solid phase with the exception of silver polyphosphate, the crystallization field of which was very limited. The enthalpy of fusion of the polyphosphate Pr(PO₃)₃ was determined from the DTA curve. The melting enthalpy of Pr(PO₃)₃ calculated from the different binary systems was approximately equal to the measured value. The calculated temperatures and compositions were in good agreement with those determined experimentally. This revised version was published online in July 2006 with corrections to the Cover Date.     

Langendorff灌流心脏的31P NMR谱测定

测定了Langendorff灌流大鼠和兔心脏的³¹P NMR谱.观测到PCr、ATP、SP、P_i以及PME和GPC等含磷代谢物的共振峰,各谱峰之间实现了很好的分辨.在3~5min的累加时间内测得的图谱具有较好的S/N,可用于以上含磷代谢物的定量测定,以高能含磷化合物ATP和PCr相对峰强度以及冠脉流量的变化对灌流大鼠心脏代谢的稳定性进行了考察,结果表明,在本实验条件下大鼠心脏的能量储存至少可稳定2h,用所建方法以3min的时间间隔对同一大鼠心脏缺血21min及再灌注12min过程中心脏的³¹P NMR谱进行了连续跟踪测定,并初步观测了缺血及再灌注过程中心肌细胞内ATP、PCr与P_i之间的消长关系.