Misra S N
Chemistry Department, Bhavnagar-University.
Indian J Biochem Biophys. 1990 Oct;27(5):284-90.
Absorption difference and comparative absorption spectrophotometric studies on praseodymium(III) and fluorouracil, fluorocytosine, fluoroadenine, fluorothymine, fluorouridine, fluorocytidine, fluoroadenosine and fluorothymidine systems at pH approximately 5.5 and in different stoichiometries in 80% DMF medium have been carried out. Magnitudes of spectral parameters, viz. Coulombic (Fk), spin-orbit (zeta 4f), nephelauxetic (beta), bonding (b), intensity (T lambda Judd-Ofelt), and oscillator strength (P) and their variation have provided information on the binding mode of these biomolecules in terms of outer and inner sphere complexation, degree of covalency and extent of 4f orbital involvement. Preliminary ultrasonic studies have indicated that these biomolecules behave as structure breakers, hence weak ligands in aqueous medium, while strengthening water structure in semi-nonaqueous medium. The analysis of the isolated solid complexes has suggested octa- and nona-coordination for praseodymium(III) in fluorinated nucleic bases and fluorinated nucleoside complexes.
在pH约为5.5的80%二甲基甲酰胺（DMF）介质中，以不同化学计量比开展了镨（III）与氟尿嘧啶、氟胞嘧啶、氟腺嘌呤、氟胸腺嘧啶、氟尿苷、氟胞苷、氟腺苷和氟胸苷体系的吸收差异及比较吸收分光光度研究。光谱参数的大小，即库仑力（Fk）、自旋轨道（ζ 4f）、电子云扩展（β）、键合（b）、强度（Tλ贾德 - 奥费尔特）和振子强度（P）及其变化，提供了有关这些生物分子在外层和内层球络合、共价程度以及4f轨道参与程度方面的结合模式信息。初步的超声研究表明，这些生物分子在水介质中表现为结构破坏剂，因此是弱配体，而在半非水介质中会强化水结构。对分离出的固体配合物的分析表明，在氟化核酸碱基和氟化核苷配合物中，镨（III）具有八配位和九配位。
