Thiols, functionalised

Fig. 56 Synthesis of thiol-functionalised dextran by conversion of dextran with acetylthiosuccinic anhydride...

The use of imprinted polymer ion separation and photometric detection has been demonstrated for Pb [19] and for U02 [35]. In the case of Pb ", the imprinted Pb " resin described above was packed into columns and used to remove Pb " from tap and seawater at a variety of pH values [8], The extraction efficiency of the imprinted resin was compared to the efficiency of an imidodiacetate resin (Chelex-100), a thiol-functionalised resin (Duolite G-73) and a high-capacity polyacrylic acid/polyvinyl alcohol resin (a proprietary NASA resin). The imprinted polymer s extraction efficiency was equal or better than the other resins and the effluents from the imprinted polymer resin were shown to be virtually free of contamination by other metal ions (Fig. 19.13). The purity of the effluent allowed the determination of Pb using a very non-specific colorimetric reagent, dithizone. The method is suitable for automation as an FIA technique. 

Figure 36. Preparation of Pt-nanoparticles 34 stabilized by the thiol-functionalised IL 33.

Thiol-functionalised mesoporous silica molecular sieve HMS-SH was synthesized at room temperature from a gel containing 0.8 mol tetraethoxysilane (TEOS), 0.2 mol 3-mercaptopropyltrimethoxysilane (MPTS), 0.275 mol n-dodecylamine, 8.9 mol ethanol and... 

Antifouling activity is one of the most important properties that catheters should ideally exhibit in order to prevent catheter-associated infections. To quantitatively investigate bacterial fouling on polymer-coated silicone rubber surfaces, the number of viable bacterial cells on the surfaces was measured [102]. After 1 day of incubation, there was a high number of viable Staphylococcus aureus and Escherichia coli cells on both pristine and thiol-functionalised surfaces (Staphylococcus aureus 8.8 and 8.6 log colony forming units (CFU), respectively Escherichia coli 8.5 and 8.2 log CFU, respectively) (Figure 6.1). 

Pristine PDMS silicone and thiol-functionalised surfaces, and surfaces coated with the two polymers, were tested against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. With the pristine surface serving as the control, the killing efficiency of the thiol-functionalised surface and surfaces coated with the two copolymers was studied. The number of Staphylococcus aureus in solution decreased slightly when the solution was incubated with the thiol-functionalised... 

Shalom, D., et al.. Synthesis of thiol functionalised gold nanoparticles using a continuous flow microfluidic reactor. Mafen o/s Leffers, 2007,61 1146-1150. 

A related thiol- functionalised rhodamine-based chemodosimeter selective for Cu irais, and with promising exploitation in microarray devices, has been recently proposed by Kim and cowoikers [65],... 

A poly(propylenamine) dendrimer (11, Fig. 6.37) functionalised with poly-(N-isopropylacrylamide) (PIPAAm) (see Section 4.1.2) was used as dendritic host for anionic cobalt(II)-phthalocyanine complexes (a, b) as guests, which are held together by supramolecular (electrostatic and hydrophobic) interactions [57]. These dendritic complexes were investigated as catalysts in the above-mentioned oxidation of thiols, where they show a remarkable temperature dependence the reaction rate suddenly increases above 34°C. One attempted explanation assumes that the dendritic arms undergo phase separation and contraction above the Lower Critical Solubility Temperature (LCST). At this temperature the phthalocyanine complex site is more readily accessible for substrates and the reaction rate is therefore higher. 

There is a vast range of chemistry of functionalised thiols that act as sensitiser electrode coatings in sensing. To take just one example, a ferrocene derived thiol receptor containing amide functional groups... 

Scheme 15.2 Synthesis of functionalised gold nanoparticles via the in situ reduction of Au(III) in the presence of a functionalised thiol.33...

One reason for the nitro group was to use conjugate addition 23a of the thiol 25 to nitroethylene 24. Now it is clear that allylic functionalisation of cycloheptene 27 is the first step. In the... 

The behaviour of phosphonodithioformates has been extensively examined by Masson and recently reviewed [36, 155]. Among the nucleophiles used, phosphites have been shown to provide new phosphonium ylides. Other reagents (organometallics, radicals, amines, thiols) have been employed for carbon-carbon bond formation and synthesis of new functionalised phosphonates, of potential biological interest. 

The present work reports such an approach with the synthesis of (vinyl)polystyrene polyHIPEs and their functionalisation by free radical addition of thiols to the remaining unsaturations. The interest of such materials is proven by the presentation of an application of a thiol functional support in free radical reduction of alkyl halides. 

The functionalisation by thiols was performed as follows Small cubes of (vinyl)polystyrene polyHIPE [3.00 mmol C=C/g (1 g, 3 mmol C=C)] were impregnated with toluene by freeze-drying under vacuum and suspended in toluene (20 mL). The thiol (8 mmol), AIBN (5 mg, l%mol. / C=C) were then added. The suspension was heated at 70°C for 48 h. The polymer was filtered off, extracted with acetone overnight on a Soxlet apparatus and dried in vaccum at 60°C, overnight. 

The functionalisation of these residual pendant vinyl group by its extremity would be a convenient way to incorporate a dimethylene spacer for more stable attachments of the grafted species through a non-benzylic position. Thiols adding to olefins under an anti-Markovnikov way by free radical mechanism8, this approach was used to diversely functionalise our polyHIPEs (scheme 2). 

Degrees of functionalisation of the modified resins were in the range 10-60% according to the thiol and the method employed the grafted function contain was between 0.25 and 1.9 mmol/g of polymer. 

Scheme 3 Functionalisation of (vinyl)polystyrene polyHIPE by thiols (numerical data are the functionalisation levels in mmol/g).

For sensitive substrates, transace talisation using ethane thiol in the presence of a mild Lewis acid such as zinc(Il) triflate is especially advantageous. Scheme 3.52. taken from a synthesis of Zaragozic Add, illustrates the method for the removal of a benzylidene acetal in a densely functionalised substrate whilst pre-... 

The C17S mutant reacts cleanly with a number of thiol-specific agents, e.g. p-nitrophenyldisulphide, and a number of saturated and functionalised acyl residues can be cleanly added to the protein via the corresponding acyl imidazolides. In all cases the extent of fidelity of acylation can be monitored by ESMS. ... 

The proteinaceous a-amino acids are all available. They have the general structure 3 where R can be an alkyl group or a variety of substituted groups.3,4 There are full listings in many textbooks.62 Important members of this class described in the chapter include phenylalanine 4, valine 5, proline 6, glutamic acid 7, aspartic acid 9, alanine 149 and leucine 163. To these we add two functionalised amino acids, the thiol cysteine 343 and the amine lysine 344 with two heterocyclic amino acids, the imidazole histidine 345 and the indole tryptophan 346. 

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