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

Abstract

[Pd(BHEP)Cl₂] 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 P₂1, a = 9.5740(8) Å, b = 9.4700(7) Å, c = 9.7890(10) Å, α = 90.00°, β = 113.360(5)°, γ = 90.00°, V = 814.78(13) ų, 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.

Keywords:

• 1,4-Bis(2-hydroxyethyl)piperazine
• cylcobutanedicarboxylic acid
• DNA
• X-ray single crystal
• DFT calculation
• stability constants

Disclosure statement

No potential conflict of interest was reported by the authors.