磷酸钙骨水泥水化机理研究进展

本文综述了Ca(H2PO4)2·H2O-Ca3(PO4)2-Ca4(PO4) 2O,Ca4(PO4)2O-CaHPO4,α-Ca3(PO4)2-少量β-TCP、HAP,β-Ca3(PO 4)2-CaHPO4·H2O-CaCO3及α-Ca3(PO4)2-Ca(H2PO4)2·H2O -CaCO3等几种主要磷酸钙骨水泥体系的特点和水化机理研究进展.     

第22届IChO理论题答案

无机化学1.反应方程（1）Ca3（PO4）2+4H3PO4→ 3Ca（H2PO4）2（2）CaF2+2H3PO4→ Ca（H2PO4）2+2HF↑ （3）CaCO3+2H3PO4→ Ca（H2PO4）2+CO2↑+H2O （4）Ca3（PO4）2+2H2SO4+4H2O →2CaSO4·2H2O     

磷酸钙在凝胶体系中的仿生矿化研究

通过模拟牙釉质的生物矿化过程,在琼脂凝胶体系中研究两种磷酸钙晶体—磷酸八钙(Ca8H2(PO4)6.5H2O,OCP)和羟基磷灰石(Ca10(PO4)6(OH)2,HAP)的矿化过程:分别研究了不同pH值(pH=6.5,7.0,7.5)条件下以及添加I型胶原蛋白的凝胶体系中矿化所形成的磷酸钙晶体的组成和形貌。在凝胶体系中,当pH=6.5时主要形成OCP,形貌为较大尺寸的片状;pH=7.0,则形成了较短片状OCP与针状HAP的混晶;pH=7.5,则主要形成针状形貌的HAP。此外,当添加Ⅰ型胶原蛋白后,在pH=6.5时则主要形成较大尺寸的片状HAP,且互相平行排列成束。由实验结果可知:pH对凝胶体系中仿生合成的磷酸钙晶体的组成和形貌具有一定的调控作用,而Ⅰ型胶原蛋白则有利于诱导形成片状HAP晶体并且使之排列呈束状,其结构类似牙釉质晶体。     

三苯基氧化膦与氯金酸形成的萃合物晶体的合成、特性和结构

本文报道了三苯基氧化膦与氯金酸形成的两种配合物晶体的合成、特性和结构.由元素分析及谱学特性确定了萃合物的组成分别为HAuCl~4·2(C~6H~5)PO(1)和HAuCl~4·2(C~6H~5)PO(2).X射线结构分析确定了两种单晶的结构.晶体(1)属于单斜晶系,空间群为C2/c,组成化学式为[(Ph~3PO)~2H]·AuCl~4,其中存在有对称氢键.晶体(2)属于三斜晶系,空间群为PI,组成化学式为(H~3O)·[AuCl~4]·4Ph~3PO,其是存在有分叉氢键.     

油包水型微乳中层柱状磷酸锆的制备与表征

以氧氯化锆(ZrOCl2·8H2O)和磷酸三丁酯(C4H9O)3PO为原料, 在正庚烷(C7H10)-十六烷基三甲基溴化铵(CTAB)/正丁醇(C4H9OH)-水的反向微乳体系中制备了Zr(HPO4)2·H2O, (H3O)+Zr2(PO4)3和Zr(HPO4)8·H2O三种不同结构的层柱状磷酸锆. 运用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射仪(XRD)等仪器对产物进行了表征, 考察了不同微乳组成对磷酸锆结构及尺寸的影响. 结果表明, 微乳体系对层柱状磷酸锆的可控制合成具有广泛意义.     

新型杂多化合物[(CH3CH2)4N]4H3O· {Na[(HMo2O5)3(HPO4)(H2PO4)3]2}·(H2PO4)2·10H2O的水热合成与晶体结构

杂多化合物在催化、医药、材料及光化学等方面具有广泛的应用前景 [1～ 4 ] ,其中钼磷多金属氧酸盐具有优异的氧化催化性能 [5,6 ] .近年来合成的新奇结构的钼磷多金属氧酸盐中已测定结构的有含帽[7,8] 和非帽[9～ 12 ] 系列 .本文利用水热法合成了未见文献报道的结构新颖的夹心型磷钼多金属氧酸盐[( CH3CH2 ) 4N]4 H3O{Na[( HMo2 O5) 3( HPO4 ) ( H2 PO4 ) 3]2 }· ( H2 PO4 ) 2 · 1 0 H2 O,并测定了其晶体结构 .1　实验与晶体结构分析1 .1　仪器与试剂　元素 Na用美国原子吸收分光光度计测定 ;C,H和 N用 Perkin- Elmer 2 4 0…     

三苯基氧化膦与氯金酸形成的萃合物晶体的合成、特性和结构

本文报道了三苯基氧化膦与氯金酸形成的两种配合物晶体的合成、特性和结构.由元素分析及谱学特性确定了萃合物的组成分别为HAuCl_4·2(C_6H_5)_3PO(1)和HAuCl_4·H_2O·4(C_6H_5)_3PO(2).X射线结构分析确定了两种单晶的结构.晶体(1)属于单斜晶系,空间群为C2/c,组成化学式为[(Ph_3PO)_2H]·AuCl_4,其中存在有对称氢键.晶体(2)属于三斜晶系,空间群为PI,组成化学式为(H_3O)·[AuCl_4]·4Ph_3PO,其中存在有分叉氢键.     

铈及氟铈联用对CaHPO_4·2H_2O在水溶液中的转化产物的影响

以XRD和IR为表征手段 ,以恒pH法为溶解实验方法 ,研究了 37℃下以铈单独处理和氟铈联用处理对二水磷酸氢钙 (CaHPO4 ·2H2 O ,DCPD)的水化产物及其溶解性质的影响。Ce3 不能促进DCPD向磷灰石转化 ,氟铈联用可加快DCPD的转化。随着Ce3 浓度的提高 ,DCPD经含Ce溶液单独处理后的产物主要为CaHPO4 (DCPA) Ce(PO4 )和Ce(PO4 )。DCPD经氟铈联用处理后的产物主要为DCPA (Ca2 ,Ce3 ) 1 0 -x(PO4 ) 6 -yF2 (F Ce HAP) Ce(PO4 )和F Ce HAP Ce(PO4 )。经 1?Cl3溶液单独处理后的DCPD的抗酸能力已有显著提高。氟铈联用促进溶解度更低的F Ce HAP的形成 ,因此效果优于铈单独处理 ,有可能成为一种有效的防龋方法。     

采用AlCl_3-EMIC-MgCl_2室温离子液体电沉积制备铝-镁合金（英文）

采用恒电流和恒电位技术,以及路易斯酸氯化铝(III)-1-乙基-3-甲基咪唑氯化物离子液体中添加氯化镁(II),室温下在铂和铜阴极表面电沉积制备了铝-镁合金.合金层中镁的含量随离子液体中氯化镁浓度和所施加的阴极电流密度的增加而增加.采用X-射线衍射谱(XRD)、扫描电子显微镜(SEM)和能量散射X-射线谱(EDAX)技术,研究了不同电沉积实验条件得到的电沉积层的晶体结构及表面形貌.增加沉积电流密度,可以制备出致密、光亮和结合力良好的电沉积层.铝-镁合金电沉积的阴极电流效率可达99%.应用电化学石英晶体微天平(EQCM)技术研究了电沉积合金的组成.根据重声阻抗分析得到的质量-电荷(m-Q)曲线斜率计算了金属共沉积层的化学成分.     

NH4+-Mg2+-pO3-4-H+-H2O体系的优势区相图

通过优势区相图的构建对NH4+-Mg2+-PO43-H+-H2O体系的热力学平衡关系进行了研究.在不同镁、磷物质的量比和离子强度的条件下绘制了lgCT,Mg-lgC,T,P和lgCT,p-pH相图,确定了MgNH4PO4·6H2O、Mg3(PO4)2· 8H2O、MgHPO4· 3H2O和Mg(OH)2的热力学稳定区.结果表明,在相当广的pH范围内,MgNH4PO4·6H2O和Mg3(PO4)2·8H2O都是主要存在的固相;在较低pH和较高磷浓度的条件下,MgNH4PO4·6H2O和MgHPO4· 3H2O可以共存;而MgNH4PO4·6H2O和Mg(OH)2在碱性条件下更为稳定.当MgNH4PO4·6H2O、Mg3(PO4)2· 8H2O与液相共存、pH=9.08～9.52时,溶液总氮浓度达到最低值.lgCT,Mg-lgCT,P和lgCT,P-pH相图可以用于指导磷酸铵镁的沉淀-溶解平衡过程,有利于废水中氨氮的脱除和回收.     

电极/溶液界面pH值的现场测量

一般认为阴极表面功能陶瓷电沉积层的形成是由于基底 /溶液界面化学环境变化造成的 [1,2 ] ,但目前还没有直接的实验数据加以证明 .原位测量电极 /溶液界面 p H的变化存在两方面的困难 :(1 )传统方法是采用玻璃 p H计 ,由于其体积较大、强度脆弱等原因 ,使其在测量固 /液界面化学环境变化的应用方面受到一定限制 [3 ] ;(2 )将 p H微探针置于电极表面 ,将会影响功能陶瓷在电极表面的沉积 ,从而使测定的界面 p H值不能真实反映电沉积过程中固 /液界面化学环境的变化 .本文基于功能陶瓷电沉积过程不受影响的情况下现场直接测量电极 /溶液界面…     

Synthesis of Calcium Phosphates by Gas-Solid Reaction of CaO-P 2 O 5

Calcium phosphates are useful materials in fertilizer, dentifrice, biomaterials, etc., and have been popularly synthesized by a wet method, a hydrothermal method, a flux method, and a solid-state reaction method. However, there has been no report on synthesis by chemical vapor deposition (CVD) method or gas-phase reaction. In the present study, calcium phosphates were synthesized by gas-solid reaction of CaO solid and P 2 O 5 gas. The CaO/P 2 O 5 ratio of starting materials was changed from 5.06 to 0.64, and the reaction was carried out at 400-1100;C. These calcium phosphates were investigated using X-ray diffractometry (XRD) and scanning electron microscope (SEM). By gas-solid reaction of CaO-P 2 O 5 , g -MET only was synthesized at 400-500;C, g -MET, HA, and g -PYR at 600-700;C, and g -MET, HA, g -PYR, and g -TCP above 800;C. Synthesized calcium phosphates were independent on the CaO/P 2 O 5 ratio of starting materials but dependent on the reaction temperature.     

Biological and medical significance of calcium phosphates

The inorganic part of hard tissues (bones and teeth) of mammals consists of calcium phosphate, mainly of apatitic structure. Similarly, most undesired calcifications (i.e. those appearing as a result of various diseases) of mammals also contain calcium phosphate. For example, atherosclerosis results in blood-vessel blockage caused by a solid composite of cholesterol with calcium phosphate. Dental caries result in a replacement of less soluble and hard apatite by more soluble and softer calcium hydrogenphosphates. Osteoporosis is a demineralization of bone. Therefore, from a chemical point of view, processes of normal (bone and teeth formation and growth) and pathological (atherosclerosis and dental calculus) calcifications are just an in vivo crystallization of calcium phosphate. Similarly, dental caries and osteoporosis can be considered to be in vivo dissolution of calcium phosphates. On the other hand, because of the chemical similarity with biological calcified tissues, all calcium phosphates are remarkably biocompatible. This property is widely used in medicine for biomaterials that are either entirely made of or coated with calcium phosphate. For example, self-setting bone cements made of calcium phosphates are helpful in bone repair and titanium substitutes covered with a surface layer of calcium phosphates are used for hip-joint endoprostheses and tooth substitutes, to facilitate the growth of bone and thereby raise the mechanical stability. Calcium phosphates have a great biological and medical significance and in this review we give an overview of the current knowledge in this subject.     

Mineralization mechanism of calcium phosphates under three kinds of Langmuir monolayers

Three kinds of Langmuir monolayers formed by dipalmitoylphosphatidylcholine (DPPC), arachidic acid (AA), and octadecylamine (ODA) were used as templates to study the initial stage of nucleation and crystallization of calcium phosphates. It was demonstrated that the combination of calcium ions (or phosphates) to the monolayer/subphase interface is a prerequisite for subsequent nucleation. It was found that calcium phosphate dihydrate (DPCD) formed at 25.0 degrees C for 12 h has a biphasic structure containing both amorphous and crystalline phases. These results showed that calcium phosphates were formed through a multistage assembly process, during which an initial amorphous phase DPCD was followed by a phase transformation into a crystalline phase and then the most stable hydroxyapatite (HAp). This provided new insights into the template-biomineral interaction and a mechanism for biomineralization.     

Templating route for mesostructured calcium phosphates with carboxylic acid- and amine-type surfactants

Mesostructured calcium phosphates constructed by ionic frameworks were synthesized using carboxylic acid- and amine-type surfactants in mixed solvent systems of ethanol and water. A lamellar mesostructured calcium phosphate was prepared using palmitic acid as an anionic surfactant, as in the case using n-alkylamines. A wormhole-like mesostructured calcium phosphate can be obtained using dicarboxyl N-lauroyl- l-glutamic acid, whose headgroup is larger than that of palmitic acid. Similar mesostructured product was obtained using 4-dodecyldiethylenetriamine with a large headgroup containing two primary amine groups. Interactions of carboxyl and primary amino groups in the surfactant molecules with inorganic species are quite important for the formation of mesostructured calcium phosphates. The Ca/P molar ratio of mesostructured calcium phosphates was strongly affected by the molecular structure of surfactants containing carboxyl and primary amino groups. Ca-rich materials can be obtained using carboxylic acid-type surfactants (Ca/P approximately 1.7) rather than amine-type surfactants (Ca/P approximately 1.0).     

Nature and Thermal Behavior of Precipitated Calcium-Magnesium Phosphates

A group of crystalline and amorphous calcium-magnesium phosphates were prepared by exchange in solution of sodium orthophosphate and calcium and magnesium chlorides at pH 8-12. The behavior of the phosphates on heating to 1000°C was studied.     

Effect of Thermal Treatment on Sorption Activity of Calcium and Magnesium Phosphates

The effect of thermal treatment in the range 20-800°C on the activity of hydrated calcium and magnesium phosphates in recovery of heavy metal ions from aqueous solutions was studied. The composition and sorption properties of materials obtained in all stages of thermal treatment of hydrophosphates and phosphates are considered. The manner in which the sorption activity of phosphates changes upon thermal treatment is interpreted.     

Synthesis of prolonged-release drugs for osteoplasty that are based on chemically modified calcium phosphates

In order to use hydroxyapatite and other biocompatible calcium phosphates as carriers for local prolonged-release drug, it is necessary to have an active component capable of retaining the preparation deposited onto the carrier surface for a long time (at least, for a few days). The grafting of the layer of active functional groups onto the carrier surface is employed to affect kinetic adsorption-desorption characteristics of calcium phosphates. The method of chemical modification of biocompatible calcium phosphates that uses B(OC₄H₉)₃, SiCl₄, POCl₃, PCl₅, and SnCl₄ is developed. The effect of the modification of calcium phosphate’s surface on the kinetics of hydrolytic desorption of octadecylamine and tetraethylenepentamine modeling the hydrophobic and hydrophilic drugs, respectively, as well as gentamicin, an antibiotic that is widely used in clinical practice to prevent and cure inflammation processes upon the damage of bony tissue, is studied. It is shown that the rate of desorption of these substances from calcium phosphates into the aqueous phase is significantly retarded when the carrier surface is preliminarily modified. By means of ESR and IR Fourier spectroscopy, the interaction of octadecylamine and tetraethylenepentamine with calcium phosphate’s surface is investigated. A conclusion about the existence of two mechanisms of adsorption of amines on modified calcium phosphates is drawn. The procedure for the preparation of biocompatible calcium phosphates with hemisorbed gentamicin is developed.     

Constant composition dissolution of mixed phases. II. Selective dissolution of calcium phosphates

Characterization of the dissolution kinetics of individual synthetic and biological calcium phosphates is of considerable importance since these phases often coexist in biological minerals. The constant composition method has been used to study the dissolution kinetics of a series of synthetic calcium phosphates, brushite (DCPD), beta-tricalcium phosphate (TCP), octacalcium phosphate (OCP), hydroxyapatite (HAP), and carbonated apatite (CAP) in the presence and absence of citric acid, as a function of pH and thermodynamic driving force. While citric acid markedly accelerates the dissolution of TCP, HAP dissolution is significantly inhibited. Moreover, this additive has almost no influence on the dissolution of DCPD, OCP, and CAP. Dual constant composition dissolution studies of mixed calcium phosphates in the presence of citric acid have also been made. Another factor, pH, also plays an important role in the dissolution of these calcium phosphates. In suspensions of calcium phosphate mixtures, specific phases can be selectively dissolved by changing experimental parameters such as pH and the presence of rate modifiers. This result has important applications for the dissolution control of dental hard tissues such as dentin, enamel, and calculus.     

Production of condensed phosphate by plasma chemical treatment of phosphate raw material

Thermodynamic calculations and experimental studies have demonstrated that dissociation of natural phosphates in a low-temperature plasma involves partial calcium oxide evaporation. As a result, upon cooling gaseous products of the dissociated phosphate raw material, compounds containing condensed calcium phosphate are formed. The composition and properties of condensed calcium phosphates, which can be used as fertilizers, are discussed.