Tailoring of Transition Metal Alkoxides Via complexation For The Synthesis of Hybrid Organic-Inorganic Sols and Gels

1992 ◽  
Vol 271 ◽  
Author(s):  
C. Sanchez ◽  
M. In ◽  
P. Toledano ◽  
P. Griesmar
Keyword(s):  
Transition Metal ◽  
Chemical Control ◽  
Sol Gel ◽  
Particle Growth ◽  
Metal Alkoxides ◽  
Network Modifier ◽  
Surface Protection ◽  
Nlo Properties ◽  
Condensation Reactions

ABSTRACTThe chemical control of hydrolysis-condensation reactions of transition metal alkoxides can be performed through the modification of the transition metal coordination sphere by using strong complexing ligands (SCL). Complexing organic groups can be bonded to the transition metal oxide network in two different ways, as network modifiers or network formers. Different illustrations of the role of complexing ligands on Ti(IV) and Zr(IV) alkoxides are presented. As a network modifier, SCL act as termination agents for condensation reactions allowing a control of particle growth. The complexing ligands being located at the periphery of the oxo core open many opportunities for colloid surface protection. SCL carrying organofunctional groups which exhibit non linear optical (NLO) properties have also been used as probes to study sol-gel transformations. SCL functionalized with organic polymerizable functions act as network formers. Hybrid organic-inorganic copolymers intimately interpenetrated on a nanometer size scale were synthesized from zirconium oxo polymers chemically bonded to polymeric methacrylate chains via a complexing function.

A Molecular Route to Dip-coated Transition Metal Nitride Thin Films.

2004 ◽  
Vol 848 ◽  
Author(s):  
Andrew W. Jackson ◽  
Andrew L. Hector
Keyword(s):  
Thin Films ◽  
Transition Metal ◽  
Spin Coating ◽  
Sol Gel ◽  
Particle Growth ◽  
Dip Coating ◽  
Stable Emulsion ◽  
Transition Metal Nitride ◽  
Sol Gel Synthesis ◽  
Gel Processing

ABSTRACTThere is an increasing interest in sol-gel synthesis of nitrides. The ability to deposit films of these materials by dip- or spin-coating will increase the range of applications in which they are viable and is an important step toward general sol-gel processing of nitride materials.With transition metals, the ammono based analogue of the well established alkoxy route to gels is inherently difficult to control. Due to the basicity of the system, the overwhelming tendency is of the starting materials to favour particle growth which results in a precipitate rather than a stable emulsion, unless both environment and synthetic pathway are carefully controlled. Hence reports to date of sol-gel routes to nitrides describe production of powders. We report work on a sol-gel route to titanium nitride with the ammonolysis of titanium amides controlled by temperature and chemical moderators, resulting in stable emulsions useful for dip-coating.

scholarly journals Spinnability of Silica Sols: the Role of Alkoxy Group Exchange

1994 ◽  
Vol 346 ◽  
Author(s):  
S. Prabakar ◽  
R.A. Assink ◽  
A.D. Irwin
Keyword(s):  
Sol Gel ◽  
Alkoxy Group ◽  
Condensation Reactions ◽  
Hydrolysis And Condensation ◽  
Silica Sols

ABSTRACTThe exchange and spinnability of several systems with the general form Si(OR)4 (where R = CH3, C2H5) in ethanol, propanol and butanol were investigated. We have followed the alkoxy group exchange, the hydrolysis and condensation reactions and the Q distributions of these systems using 29Si and 17O NMR. The observed differences in spinnability of the various sol-gel systems are attributed to the effect of the bulkiness of the alkoxy group on its reactivity.

Electrochemical Investigations on Liquid-State Polymerizing Systems:  Case of Sol−Gel Polymerization of Transition Metal Alkoxides

1998 ◽  
Vol 102 (7) ◽  
pp. 1193-1202 ◽  
Author(s):  
Hélène Cattey ◽  
Pierre Audebert ◽  
Clément Sanchez ◽  
Philippe Hapiot
Keyword(s):  
Transition Metal ◽  
Liquid State ◽  
Sol Gel ◽  
Metal Alkoxides

Sol-gel processing of transition-metal alkoxides for electronics

1993 ◽  
Vol 5 (6) ◽  
pp. 434-442 ◽  
Author(s):  
G. Rob Lee ◽  
Joe A. Crayston
Keyword(s):  
Transition Metal ◽  
Sol Gel ◽  
Metal Alkoxides ◽  
Gel Processing

Sol-Gel Chemistry of Hydrogenosiliconates: The Role of Hypervalent Silicon Species

1990 ◽  
Vol 180 ◽  
Author(s):  
V. Belot ◽  
R. Corriu ◽  
C. Guerin ◽  
B. Henner ◽  
D. Leclercq ◽  
...  
Keyword(s):  
Sol Gel ◽  
Condensation Reactions ◽  
Sol Gel Process ◽  
Redistribution Reactions ◽  
Hydrolysis Of

ABSTRACTThe hydrolysis of organic silicates ( mainly Si(OEt)4: [TEOS] and Si(OMe)4: [TMOS]) is the key reaction in sol gel process for preparation of silica. The mechanism of this reaction is not well known because of the competition taking place between hydrolysis itself and condensation reactions (homo or heterocondensations) but also because of redistribution reactions which take place competitively. Furthermore the competition between these steps depends also on the catalysis (acid,basic or nucleophilic) [1, 3].

Chemical Availability of Bromide Dictates CsPbBr3 Nanocrystal Growth

2019 ◽  
Author(s):  
Je-Ruei Wen ◽  
Benjamin Roman ◽  
Freddy Rodriguez Ortiz ◽  
Noel Mireles Villegas ◽  
Nicholas Porcellino ◽  
...  
Keyword(s):  
Reaction Time ◽  
Growth Mechanism ◽  
Chemical Control ◽  
Critical Role ◽  
Phase Evolution ◽  
Detailed Understanding ◽  
Semiconductor Nanocrystal ◽  
Nanocrystal Growth ◽  
Chemical Availability

Lack of detailed understanding of the growth mechanism of CsPbBr3 nanocrystals has hindered sophisticated morphological and chemical control of this important emerging optoelectronic material. Here, we have elucidated the growth mechanism by slowing the reaction kinetics. When 1-bromohexane is used as an alternative halide source, bromide is slowly released into the reaction mixture, extending the reaction time from ~3 seconds to greater than 20 minutes. This enables us to monitor the phase evolution of products over the course of reaction, revealing that CsBr is the initial species formed, followed by Cs4PbBr6, and finally CsPbBr3. Further, formation of monodisperse CsBr nanocrystals is demonstrated in a bromide-deficient and lead-abundant solution. The CsBr can only be transformed into CsPbBr3 nanocubes if additional bromide is added. Our results indicate a fundamentally different growth mechanism for CsPbBr3 in comparison with more established semiconductor nanocrystal systems and reveal the critical role of the chemical availability of bromide for the growth reactions.<br>

scholarly journals Conversion of Methanol on Rutile TiO2 (110) and Tungsten Oxide Clusters: 2. The Role of Defects and Electron Transfer in Bifunctional Oxidic Photocatalysts

2021 ◽  
Author(s):  
Lars Mohrhusen ◽  
Jessica Kräuter ◽  
Katharina Al-Shamery
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Metal Oxide ◽  
Tungsten Oxide ◽  
Organic Compounds ◽  
Uv Irradiation ◽  
Organic P ◽  
Rutile Tio2 ◽  
Metal Oxide Surfaces

The photochemical conversion of organic compounds on tailored transition metal oxide surfaces by (UV) irradiation has found wide applications ranging from the production of chemicals to the degradation of organic...

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