Predictive cartography of metal binders using generative topographic mapping.

Generative topographic mapping (GTM) approach is used to visualize the chemical space of organic molecules (L) with respect to binding a wide range of 41 different metal cations (M) and also to build predictive models for stability constants (logK) of 1:1 (M:L) complexes using "density maps," "activity landscapes," and "selectivity landscapes" techniques. A two-dimensional map describing the entire set of 2962 metal binders reveals the selectivity and promiscuity zones with respect to individual metals or groups of metals with similar chemical properties (lanthanides, transition metals, etc). The GTM-based global (for entire set) and local (for selected subsets) models demonstrate a good predictive performance in the cross-validation procedure. It is also shown that the data likelihood could be used as a definition of the applicability domain of GTM-based models. Thus, the GTM approach represents an efficient tool for the predictive cartography of metal binders, which can both visualize their chemical space and predict the affinity profile of metals for new ligands.

Macrocyclic complexes of palladium(II) with benzothiacrown ethers: synthesis, characterization, and structure of cis and trans isomers.

A series of palladium(II) complexes with nitro- and formylbenzothiacrown-ether derivatives was synthesized. The spatial structure of the complexes was studied by NMR, X-ray diffraction analysis, and quantum chemical calculations (density functional theory). The cavity size and the ligand denticity were found to be crucial factors determining the geometric configuration of the thiacrown-ether complexes. Palladium(II) complexes with benzodithia-12(18)-crown-4(6) ethers were demonstrated to have a cis-configured S(2)PdY(2) fragment (Y = Cl, OAc). In the case of Pd(II) and benzodithia-21-crown-7 ethers, only complexes with a trans configuration of the S(2)PdY(2) fragment form. In the case of Pd(II) and nitrobenzomonothia-15-crown-5 ether, only 2(ligand):1(Pd) complex with trans configuration of the core fragment forms.

Theoretical study of structure and electronic absorption spectra of some Schiff bases and their zinc complexes.

Tetradentate Schiff bases (H(2)L(i)), derivatives of salicylic aldehyde (H(2)L(1), H(2)L(2)) or o-vanillin (H(2)L(3), H(2)L(4)) with ethylenediamine or o-phenylenediamine as a bridge, and their zinc complexes were studied experimentally and theoretically in view of their possible application as emitters in organic light emitting diodes (OLEDs). The composition of thin films of the complexes was analyzed using a combination of different experimental and molecular modeling techniques taking into account changes in the Gibbs free energy of dehydration and dimerization reactions. The absorption spectra of the initial Schiff bases were investigated in methanol solutions, while the absorption spectra of their zinc complexes were investigated in thin films. Experimental results of elemental analysis, IR spectroscopy, laser desorption/ionization mass spectrometry (LDI MS), and X-ray diffraction as well as theoretical analysis of electronic absorption spectra by the quantum-chemical TD DFT method demonstrate that thin films of the zinc complexes contain binuclear anhydrous molecules. This conclusion should be taken into account when considering both transport and luminescence properties of these complexes in OLED heterostructures. A comparison of the results of CIS, TD DFT/PBE, and TD DFT/PBE0 calculations reveals the crucial importance of the inclusion of the exact exchange in the E(XC) functional for the further correct description of potential energy surfaces of excited states for the systems studied.