Traditional Aqueous Routes Advantages Simple Equipment Inexpensive Materials Well Studied Disadvantages Difficult control of hydrolysis and condensation rates Inhomogeneity introduced by homocondensation Reversibility of condensation step Phase Separation M-O-M' + H-O-H ^ >■ M-OH + HO-M' 2 M-OH + 2 HO-M' < > M-O-M + M'-O-M' + 2 HOH Nonaquoeus - Nonhydrolytic -Organometallic Methods Advantages Inhomogeneity and phase separation prevented absence of water, volatile organic byproducts cannot cleave M-O-M' bonds and cause homocondensation, irreversible condensation step M = mononuclear, polynuclear clusters, building blocks M-O-X + Z-M' -» X-Z + M-O-M' Chemical control of reactivity by selecting X, Z groups Wide choice of solvents, medium polarity, reaction temperature Simplified drying to aerogels, lower surface tension Nonaquoeus - Nonhydrolytic -Organometallic Methods Advantages Synthesis of hybrid materials incorporation of water sensitive and water insoluble compounds: organometallics, coordination compounds, long aliphatic chains, clusters hydrophobic hybrid materials Template syntheses use of water sensitive and water insoluble compounds, polymers microporous and mesoporous Retention of lower coordination numbers (Al, TM), low-hydroxyl surfaces - catalysis Nonaquoeus - Nonhydrolytic -Organometallic Methods Disadvantages - Elaborate procedures and expensive precursors - Organic solvents - Exclusion of moisture - Ligand scrambling vs. elimination Nonaquoeus - Nonhydrolytic -Organometallic Methods Solid-state: solid-state thermolysis Liquid-state: sol-gel, solventless, sonochemical reactions, solution thermolysis Gas-phase: CVD, pyrosol Preparation of Oxides, Mixed Oxides, and Silicates Alkylhalide Elimination Ester Elimination Alkene Elimination Acetamide Elimination Ether Elimination Ketene Elimination Ketimine Elimination Alkylhalide Elimination Reactions M = Si, Al, Ti, Zr, V, Nb, Mo, W, Fe M-X + R-O-M' ->» M-O-M' + R-X M-X + R-O-R -► M-O-R + R-X M-O-R + X-M' ->- M-O-M' + R-X M-X + H-O-R -► M-O-R + HX M-O-R + X-M' -► M-O-M' + R-X Corriu, Vioux, Leclercq, Mutin, Montpellier Hay et al., Surrey Alkylhalide Elimination Reactions C-O bond cleava Alkylhalide Elimination Reactions heptadecane 300 °C TiCI4 + Ti(OR)4 + TOPO -► Ti02anatase 10 nm R = Me, Et, i-Pr, t-Bu + RCI Colvin et al., / Am. Chem. Soc, 1999,121, 1613 Alkylhalide Elimination Reactions CCI4,110 °C AICI3 + Si(OEt)4 + Et20 -► Al-O-Si gel 900 °C T 3AI203- 2Si02 mullite Janackovic et al., NanoStructured Materials, 1999,12, 147 Alkylhalide Elimination Reactions ci \CI AP-CVD 400 - 600 °C + -► TiOo anatase H3C-CT \ O-Et Parkin I. et al., Chem. Mater., 2003,15, 46 Ester Elimination Reactions: acetates + alkoxides Jansen, Guenther, Chem. Mater., 1995, 7, 2110 Hampden-Smith et al., Chem. Comm., 1995, 157 M = Zr, Si, Ti, Ba, Sn, Pb Ester Elimination Reactions: alkoxides + acid anhydrides Fujiwara et al., Chem. Mater., 2002,14, 4975 Ester Elimination Reactions: alkoxides + acid anhydrides o OR B O RO OR B R = Me, Et OR .B B, RO' O "OR + OR acetone 0+0 \ / o gel RO SÍ<^-0R OR 600 °C borosilicate glass Becket et al., Chem. Comm., 2000, 1499 Ester Elimination Reactions CVD , 300 - 535 °C Ti(N03)4 + Si(OEt)4-► Si02/Ti02 + 4 EtON02 Gladfelter et al., Chem. Mater., 2000,12, 2822 Alkene Elimination: ŕrá(tert-butoxy)silanolates M = Ti, Zr, Hf, Al, Cr, Cu, Zn, Mo, W, V Si Tilley et al., Berkely Alkene Elimination: ŕrá(tert-butoxy)silanolates AcO. Acetamide Elimination ,Dodec H2AICI(THF); MepZn ci .Al O O O' R + He n Gerbier et al., /. Mater. Chem. 1999, 9, 2559 Knight et al., /. Organometal. Chem. 1999, 585, 162 (RP03)Zn + 2MeH layered R = Me, Ph, thienyl, Me-thiophenyl Alkene Elimination X = Si(OtBu)3 -. AI2P2Si3014 Tilley et al., /. Am. Chem. Soc. 2001,123, 10133 Alkene Elimination: ŕrá(tert-butoxy)silanolates BulO BulO- \ O' OlBu I OlBu *OlBu P—O- BulÖ O \ °'AI^0/;'P H20 isobutene Buü O \ OlBu O \ Al M--r\ m ■—r o' 7 £ Si02 i vr ° i Pinkas J., Brlejova Z., Roesky H. W. unpublished Alkene Elimination: ŕrá(tert-butoxy)silanolates TG/% isobutene + H20 DTA 350,1 eC — i i i i i i i 1 0 100 200 300 400 500 600 700 800 Temperature/°C Alkylhalide Elimination Nonhydrolytic synthesis of NASICON Na3Zr2Si2P012 solid electrolyte, high Na+ ionic conductivity - Solid state preparation: dissolved Zr02 - Sol-gel from alkoxides: very slow hydrolysis necessary, different hydrolysis rates - Nonhydrolytic route in CH3CN Bu *Bu OP(OnBu)3 + SiCI4 + ZrfOtBu^ + NaOlBu -> "BuCI + lBuCI + q CI O 1 I I B u-O—P—O—^i-O-Zr-O-t B u O CI O Gel formation I Solvent and byproduct evaporation under vacuum Bu Drying at 120 °C for 15 h Ball milling Di Vona et al^ j Sol-Gel Set TechnoL, 2000,1/3, 463 Calcination at 800 °C gives NASICON Ether Elimination Me3Si V Me Me.......IAI / Me3Si^ ^ i Me ^SiMe3 0 V Me rSiMe* CF3CH2OH - CF3CH2OSiMe3 Me Me.......fAI^ / °\ HO^-P-O' i OH OH ^ — N / -OH .AI' 1 Me Me Pinkas J., Moravec, Z., Roesky H. W. unpublished CH3-AIPO4 gel Chlororsilane Elimination THF, reflux AICI3 + OP(OSiMe3)3 -► gel AIPO4+CISiMe3 800 °C Pinkas J., et al. Inorg. Chem. 1998, 57, 2450 AIPO4 tridymite 13% Si Diketone/Ester Route on °=\-OR OR pyrosol CVD process in ethanol, 300 - 400 °C ^ AIPO4 amorphous Daviero et al., J. Non-Cryst. Solids, 1992,146, 219, Thin Solid Films, 1993, 226, 207