Krešimir Molčanov

Abstract: Five new proton transfer compounds, (Hapy)[Cr(pydc)2]·5H2O·[pydcH2] (1), (Hacr)[Cr(pydc)2]·2H2O (2), (H9a-acr)[Cr(pydc)2]·4.27H2O (3), [Co(pydc)(pydcH2)]·3H2O (4) and [Ni(pydcH)2]·H3O·2H2O (5) (where pydcH2 = pyridine-2,6-dicarboxylic acid; apy = 2-aminopyridine; acr = acridine and 9a-acr = 9-aminoacridine) have been synthesized and characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction techniques. Crystallographic analysis revealed that compounds 1–5 have distorted octahedral geometries with pydc2− and pydcH− ions or pydcH2 coordinated as tridentate ligands to each metal ion through one oxygen atom of each carboxylate group and the nitrogen atom of the pyridine ring. Compounds 1–3 consist of cationic complexes where the dipicolinic acid is coordinated to the metal ion in the dianionic form, whereas 4 and 5 are neutral complexes. In 4, the acid is coordinated to the metal ion in the neutral form, which is quite rare. In the crystal structures of the different complexes, extensive O–H⋯O, N–H⋯O and C–H⋯O hydrogen bonds, as well as other noncovalent interactions involving aromatic rings (C–H⋯π, C–O⋯π and π⋯π stacking), were described and analysed by means of density functional theory (DFT) calculations since they play an important role in the construction of three-dimensional supramolecular frameworks.

TL;DR: The antitumor activity of complexes in vitro was investigated on several human tumor cell lines and the highest activity with cell growth inhibitory effects in the low micromolar range was observed for dipalladium complexes 11 and 12 derived from dibutyl ester L6.

TL;DR: In many systems the functioning of hydrogen bonding at atomic level has been still an enigma as discussed by the authors, and it is a challenge to contrast the old and new views and to see if they could be verified or revised.

TL;DR: In this article, a series of salts with organic bases such as dimethylamine, 2-methylpyridine, 2,6-dimethyl-4-amino-pyrimidine, and R,S-tryptophane were prepared and their crystal structures determined.

TL;DR: The first systematic study is presented of π interactions between non-aromatic rings, based on the authors’ own results from an experimental X-ray charge-density analysis assisted by quantum chemical calculations.