Cinchonidine imprinting

Figure 8 Chiral HPLC separation of a equimolar mixture of (-)-cinchonidine (1) and (+)-cinchonidine (2) on a (—)-cinchonidine-imprinted stationary phase. Mobile phase, methanol -acetic acid 7 + 3 v/v. Columns 150 x 4.6 mm. Flow rate, 0.5mL/min. Detection, UV 280 nm. Reproduced from Ref. 48, with permission.

Metalloporphyrins have been used for the development of MIP for detection of a 9-ethyladenine nucleobase derivative [35]. With the increase of the template concentration, the bulk polymer exhibited a red shift in the absorbance spectra. This shift allowed for the quantitative detection of the template, which showed formation of a 1 1 monomer-template complex. Moreover, cinchonidine was imprinted using metalloporphyrin and MAA as the functional monomers [40]. The resulting MIP provided high selectivity against a diastereomer of the... 

A fluorescent MIP chemosensor for determination of 9-ethyladenine was fabricated [56]. It contained porphyrin as a luminescent functional monomer. The interaction of 9-ethyladenine with the porphyrin quenched the MIP luminescence at 605 nm when excited at 423 nm. The polymer was sensitive to 9-ethyladenine in the range of 0.01-0.1 mM however, it was already saturated at 0.15 mM. The same researchers used vinyl-substituted zinc(II) porphyrin and methacrylic acid as functional monomers for imprinting of (-)-cinchonidine [57]. The MIP luminescence, when excited at 404 nm, was significantly quenched at 604 nm upon binding of (-)-cinchonidine, even in the low concentration range of 0.01-2 mM. 

DIASTEREOSELECTIVITY OF CINCHONIDINE(l)-IMPRINTED AND CINCHONINE(2)-IMPRINTED POLYMER RODS... 

Fish WP, Ferreira J, Sheardy RD, Snow NH, O Brien TP (2005) Rational design of an imprinted polymer maximizing selectivity by optimizing the monomer-template ratio for a cinchonidine MIP, prior to polymerization, using microcalorimetry. J Liquid Chromatogr. Related Technol 28(1) 1—15... 

Fig. 34 Molecular imprinting of cinchonidine using zinc(ll)-porphyrin complex and methacrylic acid as functional monomers...

More recently, a diastereoselective molecularly imprinted fluorescent polymer for (-)-cinchonidine was prepared by the combined use of methacrylic acid and vinyl-substituted zinc(II) porphyrin monomer as functional monomers [24], Compared to the reference imprinted polymers using either MAA or zinc(II) porphyrin as a functional monomer, the imprinted polymer prepared with both MAA and the porphyrin... 

Table 8-3 Retention properties of cinchonidine(CD)-imprinted and non-imprinted polymers obtained by using two kinds of functional monomers...

For elucidation of results the authors accepted the theory of "Fingerprints". Indeed, silica formed with alkaloids reveals a greater capacity for the same alkaloid in comparison to a control adsorbent without the imprinting molecules, and silica formed with quinine adsorbs more quinine and cinchonidine, more quinidine. 

Once the imprinting system has been devised to yield favorable monomer-template complexation and the necessary porosity, the preparation of monolithic polymer rods for HPLC is relatively simple. The general protocol detailed below uses an in situ polymerization method developed by Frechet and Svec [4]. This technique was used by Matsui in the preparation of MIP monolith rods for HPLC separation of antimalarial cinchona alkaloids, ( ) cinchonidine and (+) cinchonine, as well as the structural analogues quinidine and quinine [45]. 

Fluorescence-based sensing systems offer the possibility of high levels of sensitivity and MIPs containing reporter molecules have been the subject of considerable research. There are two ways in which this may be achieved within MIPs. The simpler of the two is simply imprinting a molecule with inherent fluorescence, as demonstrated by Matsui et al. in the imprinting of cinchonidine and cinchonine. More challenging is the placement of a... 

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