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Method single bead

For on-bead analysis vibrational spectroscopy (IR-spectroscopy) can be employed attenuated total reflection is a method allowing fast and nondestructive on-bead analysis of small samples (single bead analysis) without significant sample preparation. Solid phase NMR is the method of choice if complex structural analysis is intended on the support. Spatially resolved analysis on the resin is possible with microscopic techniques. [Pg.383]

The method based on the orientation of pairs of vectors of length L produces slower dynamics than the method based on next-nearest neighbor distances. Since the acceptance rates for single-bead moves differ very little in the two methods, it appears that the probability for immediate reversal of a successful move is higher in the method based on the orientation of the pairs of vectors, such that the chain shivers rapidly, but moves its center of mass slowly. This problem is more severe in PP melts than in PE melts. Significant diffusion of the center of mass of the chains in PP melts is achieved when reptation, as well as single-bead moves, is allowed [158, 158A]. [Pg.98]

While parallel synthesis of arrays of glycopeptides is readily achieved by implementation of the building-block approach (Scheme 14.1, Strategy 2),101 glycopeptide library synthesis in a combinatorial manner via the split-mix method has yet to prove routine. The difficulty lies in the structural analysis of the vast number of compounds generated in picomolar quantities on a single bead. Whereas peptides on... [Pg.295]

FT-IR microspectroscopy is a new nondestructive, fast and rehable technique for solid-phase reaction monitoring. It is the most powerful of the currently available IR methods as it usually requires only a single bead for analysis, thus it is referred to as single bead FT-IR [166]. (See also Chapter 12 for further details). The high sensitivity of the FT-IR microscope is achieved thanks to the use of an expensive liquid nitrogen-cooled mercury cadmium telluride (MCT) detector. Despite the high cost of the instrument, this technique should become more widely used in the future as it represents the most convenient real-time reaction monitoring tool in SPOS [166, 167]. [Pg.36]

A frequent complication in the use of an insoluble polymeric support lies in the on-bead characterization of intermediates. Although techniques such as MAS NMR, gel-phase NMR, and single bead IR have had a tremendous effect on the rapid characterization of solid-phase intermediates [27-30], the inherent heterogeneity of solid-phase systems precludes the use of many traditional analytical methods. Liquid-phase synthesis does not suffer from this drawback and permits product characterization on soluble polymer supports by routine analytical methods including UV/visible, IR, and NMR spectroscopies as well as high resolution mass spectrometry. Even traditional synthetic methods such as TLC may be used to monitor reactions without requiring preliminary cleavage from the polymer support [10, 18, 19]. Moreover, aliquots taken for characterization may be returned to the reaction flask upon recovery from these nondestructive... [Pg.244]

In this experiment, cyclopentylacetic acid, 2-norbornaneacetic acid, and 1-adman-taneacetic acid reacted, respectively, with the alcohol resins (1) (Scheme 12.2) of three sizes. These resins have different diameter ranges, namely, 35-75, 160-200, and 500-560 pm. The relative conversion of the starting material to the product was determined by single bead FTIR method. Fig. 12.6 shows IR spectra taken at... [Pg.507]

To check the completion of the reaction in Scheme 12.6, the single bead FTIR measurement (Fig. 12.10) alone was not conclusive because there was no IR band from the starting resin (11) to monitor. Resin elemental analysis (Cl) of (11) could conclusively show if the reaction was complete. The accuracy and the reproducibility of the resin elemental analysis methods have been evaluated before [14]. [Pg.511]

Figure 2.6. The use of the split synthesis technique to generate a dipeptide library. After the two coupling steps shown are completed, the four possible (2 ) dipeptide sequence combinations are found. Note that any single bead will have multiple copies of the (identical) dipeptide attached and not just a single copy as shown above. This synthesis technique is economical and straightforward to undertake and requires no sophisticated equipment. The coupling steps, etc. utilized are based upon standard peptide S5mthesizing techniques, such as the Merrilield method (Box 2.1)... Figure 2.6. The use of the split synthesis technique to generate a dipeptide library. After the two coupling steps shown are completed, the four possible (2 ) dipeptide sequence combinations are found. Note that any single bead will have multiple copies of the (identical) dipeptide attached and not just a single copy as shown above. This synthesis technique is economical and straightforward to undertake and requires no sophisticated equipment. The coupling steps, etc. utilized are based upon standard peptide S5mthesizing techniques, such as the Merrilield method (Box 2.1)...
Because the characterization of support-bound intermediates is difficult (see below), solid-phase reactions are most conveniently monitored by cleaving the intermediates from the support and analyzing them in solution. Depending on the loading, 5-20 mg of support will usually deliver sufficient material for analysis by HPLC, LC-MS, and NMR, and enable assessment of the outcome of a reaction. Analytical tools that are particularly well suited for the rapid analysis of small samples resulting from solid-phase synthesis include MALDI-TOF MS [3-5], ion-spray MS [6-8], and tandem MS [9]. MALDI-TOF MS can even be used to analyze the product cleaved from a single bead [5], and is therefore well suited to the identification of products synthesized by the mix-and-split method (Section 1.2). The analysis and quantification of small amounts of product can be further facilitated by using supports with two linkers, which enable either release of the desired product or release of the product covalently bound to a dye [10-13], to an isotopic label [11], or to a sensitizer for mass spectrometry [6,14,15] (e.g., product-linker-dye- analytical linker -Pol). [Pg.5]

IR spectroscopy is a fast, simple, and cheap method for the qualitative detection of certain functional groups on insoluble supports [77-79]. Dried supports can be used directly to prepare KBr pellets for standard recording of IR spectra [54,80-82], Newer IR-based techniques, which require much less support material than required for a KBr pellet, include single-bead FT-IR spectroscopy [16,77,83-86], single-bead Raman spectroscopy [87], near-IR multispectral imaging [88], and the simultaneous analysis of several different beads by FT-IR microscopy for analysis of combinatorial libraries [89,90],... [Pg.11]

We first reported the one-bead one-compound (OBOC) combinatorial library method in 1991.1 In this method, compound beads are prepared by a split-mix synthesis approach1 3 (Fig. 1) that results in the display of many copies of the same compound on one single bead.1,4 Tens of thousands to millions of these compound beads can easily be prepared. The bead library is then mixed with a target molecule, such as a protein, an... [Pg.298]

IR methods can be used to support a proposed intermediate in a reaction [17] or to follow the incorporation of a distinctive functional group (e.g. CHO) onto a resin [8,18], IR is especially useful for surfaces such as pins or crowns, where NMR techniques are not useful. High-quality IR spectra can be obtained from single beads [19],... [Pg.60]

Mixture analysis methods are of little value for interesting sized libraries. Single-bead analysis methods are being developed which can be used to assure the quality of larger solid-phase split pool libraries. [Pg.66]

The simplest strategy for determining the structure of a compound prepared on a single bead is encoding. This indirect method of structure determination can be used both with testing methods that involve bead bound ligands as well as with solution methods that use material removed from the solid support. [Pg.292]

These techniques can be broadly split into two groups, the first of which can be represented by pooling methods, where deconvolution is obtained via various chemical steps, run in parallel or after the library synthesis. Pooling methods normally require multiple synthesis of many library members, including inactive individuals, in different pool formats. They are not single bead methods, so they are independent from analytical methods for structure determination. This group includes iterative deconvolution, recursive deconvolution, subtractive deconvolution, positional scanning and mutational... [Pg.154]

The second group can be represented by single bead methods, and relies on either bioanalytical methods to select the active compounds or on-bead screening to determine the beads carrying active compounds. It is limited to solid-phase chemistry and does not require chemical steps after library synthesis but does require sophisticated analytical methods to determine the structure of the active compounds. A recent hybrid deconvolution-single beaddecoding method named DRED (dual recursive deconvolution) requires both deconvolutive techniques and sophisticated analytical capacities. [Pg.155]

The nonchemical, robust, and automated RTF tag both for the encoding and the decoding is very appealing, and while this is not a single bead method and does not allow complete mix and split procedures, the preparation of... [Pg.223]


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See also in sourсe #XX -- [ Pg.154 , Pg.155 , Pg.170 , Pg.171 , Pg.172 , Pg.173 , Pg.174 ]




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