Tecto

Chevalier, G. Vacher, S. Deniau, J.M. and Desban. M. Disinhibition as a basic process in the expression of striatal functions. I. The striato-nigral influence on tecto-spinal/tecto-diencephalic neurons. Brain Res 334 215-226, 1985. 

More recently, mathematically defined, structure controlled, covalent megamers have been reported. They are a major subclass of megamers also referred to as core-shell tecto dendrimers) [126-128], Synthetic methodologies to these new architectures have been reported to produce precise megameric structures that adhere to mathematically defined bonding rules [91, 129], It appears that structure controlled complexity beyond dendrimers is now possible. The demonstrated structure control within the dendrimer modules, and now the ability to mathematically predict and synthesize precise assemblies of these modules, provide a broad concept for the systematic construction of nanostructures with dimensions that could span the entire nanoscale region (Figure 1.24). 

Figure 6.7 Illustration of a core-shell tecto(dendrimer) partial shell and saturated shell models.

Table 10.1 Core-shell tecto(dendrimer) molecular weight analysis results obtained from MALDI-MS, AFM and PAGE.

Figure 12.20 Schematic representation of a core-shell tecto-(dendrimer) molecule in solution...

Figure 12.21 Tapping mode AFM images of tecto-(dendrimer) molecules. (Sample preparation one drop of a 1 x 10 5wt% solution was spread on a freshly cleaved mica surface by spin coating, and then dried at room temperature)...

Based on the same equation (1), absolute molecular weight of tecto-de-ndrimers could be calculated. The results shown in Table 12.3 clearly demonstrate that the molecular weights calculated from the AFM images of individual molecules are very close to those obtained by the more classical MALDI-TOF MS and PAGE techniques. 

ATOMIC FORCE MICROSCOPY FOR CHARACTERIZATION Table 12.2 The molecular size of the core-shell tecto-dendrimers... 

Core-shell tecto-dendrimers Theoretical calculations AFM measurement ... 

Tomalia et al. reported that the surface amines of PAM AM dendrimer can successfully react with methyl esters of other PAMAM dendrimers to afford core-shell tecto-(dendrimer) molecules [65]. Furthermore, they also reported the synthesis of rod-shaped cylindrical dendronized polymers from poly(ethyleneimine) cores without any crosslinking, albeit with the use of excess reagents [58]. These reports lead us to propose a new approach toward hybridized dendrimers and polymers (path C, Figure 15.3). As shown in Scheme 12,... 

Laboratory Synthesis and Characterization of Megamers Core-Shell Tecto(dendrimers)... 

Figure 27.1 Hierarchy of empirical construction components (A) monomers, (B) branch cells, (C) dendrons and (D) dendrimers leading to (E) core-shell tecto(dendrimers)...

Laboratory procedures are presented for two divergent approaches to covalent structure controlled dendrimer clusters or more specifically - core-shell tecto(dendrimers). The first method, namely (1) the self assembly/covalent bond formation method produces structure controlled saturated shell products (see Scheme 1). The second route, referred to as (2) direct covalent bond formation method , yields partial filled shell structures, as illustrated in Scheme 2. In each case, relatively monodispersed products are obtained. The first method yields precise shell saturated structures [31, 32] whereas the second method gives semi-controlled partially shell filled products [30, 33],... 

The general chemistry used in this approach involves the combination of a limited amount of an amine-terminated dendrimer core reagent with an excess of carboxylic acid terminated dendrimer shell reagent [31]. These two charge differentiated species are allowed to self-assemble into the electrostatically driven supramolecular core-shell tecto(dendrimer) architecture. After equilibration, covalent bond formation at these charge neutralized dendrimer contact sites is induced with carbodiimide reagents (Scheme 1). 

MALDI-TOF Mass Spectrometer Conditions for PAMAM Dendrimers and Core-Shell Tecto (Dendrimers)... 

Three-dimensional or tecto-silicates Three-dimensional frameworks of [Si04] tetrahedra sharing all four oxygen atoms Feldspars, zeolites, ultramarines... 

Chrysin shows a similar effect which is much enhanced in tecto-chrysin, owing presumably to methylation of the 7-hydroxyl in techto-chrysin leaving only the keto-associated 5-hydroxyl free in that flavone. Opening the flavone heterocyclic ring to produce 2-hydroxychalcone leaves monophenol activity still partly suppressed because of the remaining carbonyl effect on oxidizability and H-bonding. Since the structure is relatively free to rotate about the ring-to-carbonyl bond, the suppression is less than in tectochrysin. 

Thiabendazole 2-(4-thiazolyl)benz imidazole APL-Luster Mertect TBZ Tecto Tobaz... 

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