Hyperfine Interact (2017) 238:87 https://doi.org/10.1007/s10751-017-1463-1 M¨ ossbauer study of novel iron(II) complexes synthesized with Schiff bases Cs. V´ arhelyi Jr. 1 · A. Lengyel 2 · Z. Homonnay 2 · R. Szalay 2 · Gy. Pokol 3 · I.-M. Szil´ agyi 3 · P. Huszthy 3 · J. Papp 4 · F. Goga 1 · L.-M. Golban 1 · M. V´ arhelyi 1 · M. Tomoaia-Cotisel 1 · ´ A. Sz˝ oke 1 · E. Kuzmann 2 © Springer International Publishing AG, part of Springer Nature 2017 Abstract Novel [Fe(4-benzyl-2-hydroxyphenyl-propylidene) 2 ethylene-diamine], and [Fe (2,4,6-trihydroxy-benzyl-4-metoxiphenyl-methylidene) 2 ethylene-diamine] complexes were synthesized by reacting Fe II salt with the indicated Schiff-base ligands. The compounds were characterized by 57 Fe M¨ ossbauer spectroscopy, FTIR, UV-VIS, TG-DTA-DTG, MS, AFM, XRD, cyclic voltammetry and biological activity measurements. 295 K and 78 K M¨ ossbauer spectra revealed that iron is dominantly in high spin Fe II state in both complexes while simultaneously a minor low spin Fe II was also present in both complexes, further- more a minor high spin Fe III was observed in [Fe(2,4,6-trihydroxy-benzyl-4-metoxiphenyl- methylidene) 2 ethylene-diamine], too. Keywords 57 Fe M¨ ossbauer spectroscopy · Fe(II) complexes · Schiff bases · High-spin Fe(II) · Low-spin Fe(II) This article is part of the Topical Collection on Proceedings of the International Conference on the Applications of the M ¨ ossbauer Effect (ICAME 2017), Saint-Petersburg, Russia, 3–8 September 2017 Edited by Valentin Semenov  E. Kuzmann kuzmann@caesar.elte.hu 1 Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Cluj, Romania 2 Institute of Chemistry, E¨ otv¨ os Lor´ and University, Budapest, Hungary 3 Faculty of Chemical and Bioengineering, Budapest University of Technology and Economics, Budapest, Hungary 4 Faculty of Biology and Geology, Babes-Bolyai University, Cluj, Romania