Lipophilicity of Metallic Complexes of 4-Methoxyphenyl - 4' - Chlorobenzoylhydrazine as Estimated from Principal Component Analysis of thin Layer Chromatographic Retention Data

ABSTRACT

The relative lipophilicity of ten metallic complexes of 4-methoxyphenyl-4'-chlorobenzoylhydrazine with Cu²⁺, Co²⁺, Mn²⁺, Ni²⁺, Pd²⁺, Fe³⁺, Cr³⁺, La³⁺, Ce⁴⁺ and UO₂ ²⁺ with potentially anti-inflammatory properties have been determined by reversed-phase thin-layer chromatography using C₁₈ plates and water-methanol mixtures as eluents. The R_F values of each compound increased linearly with increasing concentration of methanol in the eluent. Principal component analysis allowed a more rational and objective estimation and comparison of lipophilicity determined by RPTLC. Scatterplots of the scores onto a plane described by the first two components showed clustering of the complexes according to the nature of the central cation, obtaining in this way a "congeneric lipophilicity chart". Generally, the presence of cation increases the lipophilicity expressed as scores along the first principal component, practically in the same way. This means that the lipophilic behavior of metallic complexes depends firstly of the structure of ligand. However, the most lipophilic effect was observed in the case of Cu²⁺, Pd²⁺, La³⁺ and Cr³⁺.

Keywords::

• TLC
• PCA
• metallic complexes
• lipophilicity, congeneric lipophilicity chart
• chemometrics