ZHONG Shi-an; HUANG Ke-long; LEI Qi-fu; XIANG Hai-yan
A molecularly imprinting polymer (MIP) was synthesized via bulk polymerization under different conditions using anti-ague drug cinchonine (CN) as template. Infrared spectra (IR) results show that the template CNand functional monomer α-methyl acrylic acid (MAA) formed complexes before polymerization and the structure of complexes was simulated by Hyperchem. The results indicate that there are hydrogen bond or ionic bond between functional monomer and template molecule in acetonitrile solution. The MIP made in cold-initiated photo-polymerization has higher separation performance than that in the therm-initiated polymerization. The separation of the isomers CN and cinchonidine (CD) can be successfully obtained when its separate factor α reaches 1.82. Scatchard analysis suggests that the MIP recognizing CN with two classes of binding sites. The partition coefficient Kd, 1 and apparent maximum number nmax, 1 of binding sites with high affinity are 131.43 μmol/L and 58. 90 μmol/g, respectively,while Kd, 2 and nmax, 2 of binding sites with low affinity are 2.32 mmol/L and 169.08 mmol/g, respectively.
Wesełucha-Birczyńska, A.; Oleksyn, B. J.; Śliwiński, J.; Goslar, J.; Hilczer, W.; Hoffmann, S. K.
The crystal structure of (C 19H 24N 2O 2+) 2(CdCl 4) 2-(Cd 0.5Cu 0.5Cl 4) 2- has been determined by X-ray diffraction at 295 K. The compound crystallises in orthorhombic P2 12 12 1 space group with unit cell parameters: a=12.7381(10), b=13.5394(10), c=25.6520(10) Å, and Z=4. Packing of molecules in the unit cell is determined by single and bifurcated hydrogen bonds between cinchoninium cation, (cinchonineH 2) 2+, CuCl42- and CdCl42- tetrahedral anions. Specific feature of the packing is a partial stacking of the quinoline rings of adjacent cinchoninium cations. There are eight sites for M=Cd or Cu in the crystal unit cell. In the four of them the CdCl 4 tetrahedra are located. In the others Cd or Cu can be located and an average geometry (Cd/CuCl 4) is described by the X-ray diffraction data. EPR allows to observe only the CuCl 4 complexes and we have proved that there is not a random distribution of individual Cd and Cu among the (Cd/CuCl 4) sites but they are coupled in dimers, so that asymmetric unit can be identified as (cinchonineH 2·MeCl 4) 2 moiety. Specific feature of the structure is that CuCl 4 tetrahedra are relatively weakly deformed from ideal tetrahedral geometry Td towards the D2 d symmetry (flattening angle 123.3°) and have relatively long Cu-Cl bonds (2.338 Å) at 295 K. Reflectance optical absorption band at 8700 cm -1 with a shoulder at 6200 cm -1 are assigned to ( x2- y2)→( z2) and ( x2- y2)→( xy) transitions, and they follow the well-known relationship between band positions and geometry of tetrachlorocuprates. EPR shows that the exchange coupling between Cu 2+ ions is very weak and an individual CuCl 4 gives separate lines in EPR spectrum. The spectrum below 200 K is characterised with parameters gx=2.047, gy=2.127, and gz=2.404 and above this temperature becomes dynamically averaged to g∥=2.299 and g⊥=2.065. This continuous type transition to the dynamic phase, without a thermal effect, is accompanied by the change in the crystal
The optical α-amino acids were synthesized under room temperature by alkylation of N-(diphenyl methylene) glycine t-butyl ester under polymer-supported phase transfer conditions using polymer-supported cinchonine (or quinine) alkaloids as chiral phase transfer catalysts and dichloromethane as solvent, followed by hydrolysis of the above intermediates introduced to the final products-optical α-amino acids. This is a new method for the asymmetric synthesis of α-amino acids. The influences of catalyst,temperature, substrates, and organic solvents on the chemical yield and optical purities of products were studied.
Ravishankara, M N; Shrivastava, N; Padh, H; Rajani, M
We report a sensitive method for the estimation of quinine (Qn), cinchonine (Cn), and cinchonidine (Cnd) and a new method based on fluorescence enhancement and detection and quantification of quinidine (Qnd) from Cinchona stem bark and its formulations, using HPTLC. Standard solutions of Qn, Qnd, Cn, and Cnd were applied on precoated HPTLC plates and developed with chloroform/diethylamine (9.6:1.4 v/v). The plates were scanned and quantified at 226 nm for Qn, Cn, Cnd and for Qnd at 366 nm in fluorescence and reflectance mode ([symbol: see text] K400 filter). The method was validated for precision, accuracy and repeatability. Further, the stem bark of Cinchona officinalis and some herbal and homeopathic formulations were evaluated for their individual alkaloid content applying the developed method. PMID:11345710