ORIGINAL PAPER Influence of organic modifiers on RP-TLC determination of lipophilicity of some polydentate Schiff bases Danica S. Perus ˇkovic ´ • Branka Daric ´ • Anita Blagus • Nikola R. Stevanovic ´ • Aleksandra V. Pavlovic ´ • Aleksandar Ð. Lolic ´ • Rada M. Baos ˇic ´ Received: 23 June 2014 / Accepted: 11 September 2014 / Published online: 27 September 2014 Ó Springer-Verlag Wien 2014 Abstract The lipophilic character of polydentate Schiff bases was investigated by reversed-phase thin-layer chro- matography. In order to determine retention parameter as a measure of the lipophilicity of the tested compounds, three different binary solvent systems, composed of water and organic modifier (methanol, acetonitrile, and tetrahydro- furan), were used. Lipophilicity parameters together with 2D molecular descriptors were subjected to the multivari- ate statistical analysis. Principal component analysis was employed to reveal the most influential factors governing the lipophilicity of the investigated compounds. Finally, the influence of organic modifier on determination of lipophilicity parameters was discussed. Keywords Schiff bases  RP-TLC  PCA  Lipophilicity  Molecular modeling  Bioinformatics Introduction Lipophilicity is one of molecular parameters, which plays an important role in the drug design. The transport of a compound through biological membranes may be pre- sented by its lipophilicity as one of the most important intrinsic physicochemical property of the compound [1, 2]. Classic procedure for determination of lipophilicity considers determination of log P (the partition coefficient), which is descriptor of the differential partitioning of a neutral compound between two immiscible solvents, usu- ally 1-octanol and water [3]. Instead of this traditional shake-flask method, reversed-phase thin-layer chromatog- raphy (RP-TLC) is frequently used to estimate the lipophilicity of observed compounds due to the fact that the same basic intermolecular interactions determine the behavior of compound in both biological and chromato- graphic environment [4–8]. Lipophilicity parameters can be related to chemical structures of investigated compounds that were described by molecular descriptors using principal component ana- lysis (PCA). According to the PCA, the data represented in a multidimensional space, where the variables define the axes, are projected into a few principal components (PCs) which are linear combinations of the original variables and describe the maximum variation within the data [9]. Polydentate Schiff base ligands and their metal com- plexes have been extensively studied because of their preparative availability and structural variability [10]. Schiff bases synthesized from 2-hydroxy aromatic alde- hyde and different aromatic (ortho, meta, or para) diamines form either symmetrical tetradentate or bis- bidentate chelate ligands [11]. These compounds may contain a variety of substituents with different electron- donating or electron-withdrawing groups. Therefore, they have attracted particular interest due to their biological activities [12], and have been used as model systems for biological macromolecules [13]. Literature data point out that Schiff bases and complexes have several properties such as their ability to reversibly bind oxygen, catalytic activity in hydrogenation of olefins, transfer of an amino group, photochromic properties, competing abilities D. S. Perus ˇkovic ´  B. Daric ´  N. R. Stevanovic ´  A. V. Pavlovic ´  A. Ð. Lolic ´  R. M. Baos ˇic ´(&) Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, Belgrade, Serbia e-mail: rbaosic@chem.bg.ac.rs A. Blagus Department of Chemistry, J. J. Strossmayer University, Franje Kuhaca 20, Osijek, Croatia 123 Monatsh Chem (2015) 146:1–6 DOI 10.1007/s00706-014-1313-7