1、溶膠凝膠化學(xué)與工程引論,A.C. Pierre, Introduction to Sol-gel Processing (Chemistry and Engineering) 主講：夏長(zhǎng)榮，電話(huà)3607475，材料樓北217室， Email: 輔導(dǎo)：王運(yùn)龍， 考試（60），不參加考試不計(jì)成績(jī)； 分組專(zhuān)題報(bào)告（40）； 上課12周，簽到8次以上，簽到8次以下不計(jì)成績(jī)。,Simplified chart of sol-gel processes,The chemistry of precursors solutions,All types of precursors can be used, pr

2、ovided 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,水是最好的極性溶劑之一，主要原因是什么？ 舉3個(gè)非水溶劑的例子？ 極性溶劑和非極性溶劑的主要區(qū)別是什么？ 酸性、堿性、二性溶劑有何區(qū)別？ 舉例說(shuō)明Protic, Aprotic, amphoteric（質(zhì)子性、非質(zhì)子性、兩性）溶劑？,Water, H2O,The an

3、gle 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) = -0.4 Positive part

4、ial 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 interaction between

5、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, O2- practically doe

6、s 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 a weak ionizing p

7、roperty 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 a base and as an a

8、cid.,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,化學(xué)位？ CH3COOH在CH3COOH的水溶液中的化學(xué)位？ 在CH3COOH的水溶液中，CH3COOH

9、中的H與H2O中的H的化學(xué)位相等嗎？所帶電荷相同嗎？ 理論上可以確定一個(gè)溶液體系所有不獨(dú)立存在物種的化學(xué)位嗎？主要原理是什么？ 什么叫絡(luò)合物？舉例說(shuō)明。 絡(luò)合物的形成過(guò)程主要有幾種？,第一電離能和電子親和勢(shì),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 a atom;,The electr

10、onegativity 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 electronegativity ia and har

11、dness 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, both the valence sta

12、te 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)6Cl3,Nucleophilic ad

13、dition,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 reaction does not de

14、pend 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 and the leaving grou

15、ps.,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; hexadentate),3. 金屬

16、鹽溶液,4. 如果水合物不穩(wěn)定，可能發(fā)生的反應(yīng)是什么？主要產(chǎn)物？反應(yīng)進(jìn)行的條件是什么？,1. Al(NO3)3溶于水后，電離，形成Al3和NO3?,2. Al3在水中穩(wěn)定存在嗎？,3. 如果形成水合物，即Al3的絡(luò)合物，它穩(wěn)定嗎？,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 aqu

17、o ligand, H2O is transformed into an hydroxo ligand, OH-, if only one proton leaves. Into an oxo ligand, O2-, if two protons detaches.,Formation of hydroxo ligands,The first deprotonation,The successive deprotonations,The equivalent forms of the reaction,Deprotonation mechanism with hydroxo ligand,T

18、he deprotonation reaction occur as long as,(O) free water (O) complex 0,Formation of hydroxo ligands from oxo ligands,The reaction continues as long as 0 (H) complex (H) water,The mechanism,Formation of oxo ligands,Oxo-hydroxo-aquo,Partial charge model (PCM) and hydrolysis,The electronegativity of a

19、n aquo-hydroxo complex C=M(OH)h(OH2)N-h(z-h)+,Therefore,PCM and Aquo, oxo domains,The partial charge model also gives the basis for the experimental determination of the domains in which pure aquo complexes, M(H2O)Nz+, and pure oxo anions, MOm(2m-z)-, are respectively formed,Li(OH2)4+,SO42-,PCM and the first deprotonation constant K11,A 絕對(duì)值越大，越不容易水解,4. 陰離子效應(yīng),陰離子對(duì)水合鹽結(jié)構(gòu)有影響嗎？主要通過(guò)什么方式影響？ 用磷酸鹽、硝酸鹽等不同的鹽（金屬離子相同），對(duì)水合物結(jié)構(gòu)有影響嗎？ 如果對(duì)結(jié)構(gòu)有影響，勢(shì)必對(duì)溶膠凝膠過(guò)程有影響？,Complexation with anions,With a monodentate anionic group X,With a molecular group HX,Fe(OH)2(OH2)4+ with bidentate anio