Studies on Pd(1,4-bis(2-hydroxyethyl)piperazine)-dicarboxylic acid complexes as models for carboplatin with structural features enhancing the interaction with DNA

摘要

[Pd(BHEP)Cl-2] and [Pd(BHEP)(CBDA)] complexes, where BHEP = 1,4-bis(2-hydroxyethyl)piperazine and CBDA = cyclobutanedicarboxylate, were synthesized and characterized. [Pd(BHEP) (CBDA)] crystallizes in space group P(2)1, a = 9.5740(8) angstrom, b = 9.4700(7) angstrom, c = 9.7890(10) angstrom, alpha = 90.00 degrees, beta = 113.360(5)degrees, gamma = 90.00 degrees, V = 814.78(13) angstrom(3), Z = 2. The palladium center has a typical square planar geometry with tetrahedral distortion. DFT calculations show good agreement between theoretical and X-ray data. The stability constants and stoichiometry of the complexes formed between various dicarboxylic acids and [Pd(BHEP)(H2O)(2)](2+) were studied. Dicarboxylic acids form 1:1 and protonated complexes. Inosine forms 1:1, 1:2 and the protonated form of 1:1 complexes. The temperature effect on the formation constant of the cyclobutanedicarboxylate complex was investigated. The hydrolysis of [Pd(BHEP)(H2O)(2)](2+) and complex formation with cyclobutanedicarboxylic acid are exothermic processes.