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1、溶胶凝胶化学与工程引论,A.C. Pierre, Introduction to Sol-gel Processing (Chemistry and Engineering) 主讲：夏长荣，电话3607475，材料楼北217室， Email: 辅导：王瑶， 考试成绩占70，不参加考试不计成绩。 上课18周，签到14次以上（30），签到10次以下不计成绩。,210.45.126.226/ course,Simplified chart of sol-gel processes,The chemistry of precursors solutions,All types of precurso
2、rs can be used, provided they are miscible. Metallic salt MmXn, AlCl3, (NH4)2Ce(NO3)6. Alkoxides, Al(OC2H5)3, Si(OCH3)4 Organometallic compounds,1. Solvents,Water Non aqueous solvents,水是最好的极性溶剂之一，主要原因是什么？ 举3个非水溶剂的例子？ 极性溶剂和非极性溶剂的主要区别是什么？ 酸性、碱性、二性溶剂有何区别？ 举例说明Protic, Aprotic, amphoteric（质子性、非质子性、两性）溶剂？
3、,Water, H2O,The angle HOH is 104.5o in the gaseous state, and varies from 118o to 120o in the liquid state. Dipole moment, = 1.85 D (1 Debye = 3.33610-30 Cm),3a1 is delocalized, Lewis base, donating a pair of electrons 1b1 is non binding, a weak donor Negative partial charge of oxygen atom of (O) =
4、-0.4 Positive partial charge (H) = +0.2,Results of polar structure I,Water is an excellent liquid medium in which to dissolve ionic solutes,0 = 8.854210-12 Fm-1, the dielectric permittivity of vacuum r, the relative dielectric constant, r,H2O = 78.4; it consequently largely attenuates the coulomb in
5、teraction between two electrical charges.,Results of polar structure II,Molecules are bound by up to 4 hydrogen bonds to neighboring molecules. Further increase the ability to dissolve ionic solutes.,Auto-dissociate,2H2O H3O+ + HO- Kw = H3O+ HO- = 10-14 at 25oC H3O+ H9O4+ HO- H7O4-,In consequence, O
6、2- practically does not exist in water, and when a solid oxide is dissolved it immediately undergo an acid base protonation reaction,Non aqueous solvents,Non aqueous solvents,r 40, Such moleculars have good ionizing properties and can therefore dissolve other polar solute r 20, These moleculars have
7、 a weak ionizing property and can only dissove less polar solute,Classification,Protic; exchange a proton, acidic; donate a proton or accept a pair of electrons Aprotic; can not exchange a proton, base; accept a proton or donate a pair of electrons A solvent is amphoteric when it can behave both as
8、a base and as an acid.,Amphoteric solvents,Mineral acids (HCN, HX, HNO3, H2SO4, H2S) Carboxylic acids R-COOH Water, the first alcohols (CH3OH, C2H5OH, ), and phenol C6H5OH Ammonia NH3 and amines (RNH2, RRNH) Amides (R-CO-NH2, R-CO-NHR),2. Precursors transformations,化学位？ CH3COOH在CH3COOH的水溶液中的化学位？ 在CH
9、3COOH的水溶液中，CH3COOH中的H与H2O中的H的化学位相等吗？所带电荷相同吗？ 理论上可以确定一个溶液体系所有不独立存在物种的化学位吗？主要原理是什么？ 什么叫络合物？举例说明。 络合物的形成过程主要有几种？,第一电离能和电子亲和势,The first ionization energy, I1,The electron affinity, A,Chemical potential of the electrons and electronegativity of an isolated atom,The chemical potential of the electrons in
10、a atom;,The electronegativity of an isolated atom;,Therefore,Partial charge model,The partial charge model is based on the electrical interactions between the partial electric charges, , carried by each atom and molecule.,Where, a is the atom hardness,Electronegativity scales,The absolute electroneg
11、ativity ia and hardness ia concern an isolated atom I. The Mulliken iM and iM, the electronic state of an atom in its average valence structure. The Pauling iP and iP, the average structure configuration in which the atoms are engaged. The Allred and Rochow iO and iO for the partial charge model, bo
12、th the valence state and the shape of an atom X in its average polariztion.,Allred-Rochows electronegativity,Complex C such as M(OH)y(H2O)N-y(z-y)+,(C) = (H+) = (H2O),Water as an example,pH 7, water is partial charged, (H+) = o (H+) 0.06pH (H+) = (H2O) = 2.631 0.02pH,Complex transformation,Co(NH3)6C
13、l3,Nucleophilic addition,Co(NH3)53+ + NH3 = Co(NH3)63+,The direct addition of a new ligand occurs when the coordination number of the cation in the complex is not fully satisfied.,Dissociative mechanism,Ni(OH2)62+ Ni(OH2)52+ + H2O Ni(OH2)52+ + NH3 Ni(OH2)5(NH3)2+,Since the rate constant of such a re
14、action does not depend on the concentration of the entering Y ligand, this dissociative mechanism is a unimolecular nucleophilic substitution, SN1.,Associative substitution,It is a bimolecular nucleophilic substitution, SN2 since the rate constant depends on the concentration of both the entering an
15、d the leaving groups.,Interchange substitution,The reaction proceeds in only one step and this is a SN2 substitution,Bidentate,Typical chelating ligands (2; bidentate, 3; tridentate, 4; tetradentate, and 6; hexadentate),Typical chelating ligands (2; bidentate, 3; tridentate, 4; tetradentate, and 6;
16、hexadentate),3. 金属盐溶液,4. 如果水合物不稳定，可能发生的反应是什么？主要产物？反应进行的条件是什么？,1. Al(NO3)3溶于水后，电离，形成Al3和NO3?,2. Al3在水中稳定存在吗？,3. 如果形成水合物，即Al3的络合物，它稳定吗？,Metal Salts Solution,IONS SOLVATATION MX = M(H2O)nz+ + X(H2O)mz-, Z = 48, frequently 6, Al(H2O)63+, H9O4+,Hydrolysis,Hydrolysis is the deprotonation of a salvated metal cation. The aquo ligand, H2O is transformed into an hydroxo ligand, OH-, if only one proton leaves. Into an oxo ligand, O2-, if two protons detaches.,
