The scientific paper entitled "Synthesis and characterization of ML and ML2 metal complexes with amino acid substituted bis(2-picolyl)amine ligands" is the result of a multidisciplinary collaboration of Croatian and Slovenian scientist within a joint bilateral project "Catalytic and biological properties of metal complexes with nitrogen ligands", and was also in part financed by the Croatian Science Foundation within research projects "Minimal artificial enzymes" and "New nitrogen heterocycles as sensors for pH and metal ions".
Members of the research team were synthetic chemists postdoctoral student dr. sc. Đani Škalamera and technician Ernest Sanders, computational chemists doctoral student Aleksandra Maršavelski and dr. sc. Robert Vianello as well as research coordinator dr. sc. Srećko Kirin, all from RBI in Zagreb, and structural chemists dr. sc. Andrej Pevec and dr. sc. Iztok Turel from FCCT in Ljubljana.
This paper explores factors governing the ability of transition metal cations (M) for binding one or two molecules of organic tridentate ligands (L) in the ratio M : L = 1 : 1 or M : L = 1 : 2 and the spatial distribution of the ligands around the metal ions (mer, trans-fac or cis-fac stereochemistry).
In the paper, symmetric tridentate nitrogen heterocycles bis-picolylamine (L = bpa) and bis-quinaldylamine (L = bqa) were used; special attention was paid on zinc complexes [Zn(L)]2+ and [Zn(L)2]2+. Optimal reaction conditions for the preparation of the desired cis-fac-[Zn(L)2]2+ complexes were found by a systematic investigation, using nuclear magnetic resonance spectroscopy (NMR) and single crystal x-ray diffraction, in accordance with computational models, which have helped in the interpretation of the experimental observations.
The obtained results are valuable to the further research as a basis for optimization of small synthetic catalyst for asymmetric reactions with a functional outer-coordination sphere, with potential application in the pharmaceutical and chemical industries.