Directing agents, organic

Since then, organic amines, quaternary-ammonium bases, metal complexes, and other compounds have been extensively used in zeolite synthesis, acting as space fillers with low specificity, structure-directing agent, or true templates ... 

Al-containing ITQ-21 zeolite ((Si+Ge)/Al=25, Si/Ge=20) was synthesized using N(16)-methyl-sparteinium cation (MSPT+) as the organic structure-directing agent in combination with fluoride anions and germanium as described in [1], The composition of the final synthesis gel was ... 

The probable mechanism of action for all of the stable A -halamines involves direct contact of the microorganism with the combined A -halamine, followed by donation of a Cl" or Br" species to a receptor site within the cell, causing oxidation, and subsequent cell inactivation. Once the halogen content is exhausted through reaction with reducing agents, organic impurities. 

M.J., and Valenda, S. (2004) Supramo-lecular self-assembled molecules as organic directing agent for synthesis of zeolites. Nature, 431, 287-290. 

An alternative method to synthesize organically functionalized mesoporous silica phases is the co-condensation method (also called one-pot synthesis or direct synthesis). Historically, the classical co-condensation reaction involved tetraalkoxysilane [(RO Si (predominantly TEOS or TMOS)] and a terminal organotrialkoxysilane of the type (R 0)3Si-R in the presence of structure-directing agents (Fig. 3.9, top). Meanwhile, not only bis- and multi-silylated precursors are used, that is, precursors of the type [(R 0)3Si]mR, m > 2 (Fig. 3.9, bottom), together with TMOS/TEOS, but... 

Zeolites having ZSM-48 topology also crystallize from hydrogels containing other linear organic structure directing agents, such as diamines (2) or various (poly)alkylamines ( ). 

Besides their obvious role as templates or structure directing agents (12) or as stabilizing pore fillers (2,1A) the organic cations will also compete with alkali ions for the stabilization of the negatively charged framework (12,11,12). 

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