Insight on thermal behaviour of new complexes of Ni(II), Cu(II) and Zn(II) with a bismacrocyclic ligand developed as biologically active species Mihaela Badea 1 • Cristina Bucur 1,2 • Mariana Carmen Chifiriuc 3,4 • Coralia Bleotu 5 • Maria-Nicoleta Grecu 6 • Veronica Lazar 3,4 • Dana Marinescu 1 • Rodica Olar 1 Received: 29 October 2015 / Accepted: 24 April 2016 Ó Akade ´miai Kiado ´, Budapest, Hungary 2016 Abstract A multi-component reaction involving metal ion, amines and formaldehyde has been used for a series of decaaza bismacrocyclic complexes M 2 L(CH 3 COO) 4 ÁnH 2 O [(1) M: Ni, n = 2.5; (2) M:Cu, n = 1; (3) M:Zn, n = 10; L:1,3-bis(N,N-1,3,6,9,12-pentaazacyclotridecane)-benzene] preparation. Elemental analyses, ESI-MS, IR, UV–Vis– NIR, NMR and EPR spectra, magnetic susceptibility at room temperature, molar conductivities, as well as ther- mogravimetric analysis, provided data concerning com- plexes features. The macrocyclic ligand behaves as bischelate, resulting in either a square planar or an octa- hedral stereochemistry. The in vitro screening of the antimicrobial activity was performed against both refer- ence and clinical isolates multi-drug-resistant strains. The overall antimicrobial potency of complexes was enhanced in comparison with the free ligand, against both planktonic and biofilm-embedded pathogenic strains. Complexes exhibit no cytotoxicity on the HCT 8 tumour cells. Thermogravimetric curves (TG, DTG and DTA) evidenced in air processes as water elimination, acetate into carbonate transformation as well as oxidative degradation of the bismacrocyclic ligand. The powder X-ray diffraction data indicate MO (M: Ni, Cu, Zn) as final product. Keywords Complexes Á Bismacrocycle Á One-pot condensation Á Antimicrobial Á Thermal behaviour Introduction Data concerning azabismacrocyclic ligands have received much attention since the discovery of paraxylyl bicyclam (AMD3100) as HIV cell entry blocker [1]. Also, the spe- cies as Mozobil or Plerixafor are prescribed to mobilise hematopoietic stem cells for collection and subsequent transplantation in patients with non-Hodgkin’s lymphoma or multiple myeloma and entered recently in clinical trial phase for the AIDS [2, 3] and pancreatic, ovarian and colorectal advanced cancers treatments [4]. New bis(azamacrocycles) as well as their complexes have been designed and synthesised, proving interesting chemical properties (magnetic, redox or electrochemical) [5, 6] or a large spectrum of biological activity [7–9]. Binuclear complexes with bis(azamacrocycles) were also the subject of extensive investigation concerning their catalytic effects. Thus, it has been found that some dime- tal(II) complexes act as efficient catalysts in oxidative [10–13] or reductive [14–16] processes. Many bismacrocyclic complexes were studied in order to obtain a specific metallocyclam configuration in order to target the CXCR4 co-receptor, thereby interfering with the HIV entrance in the host cell [17, 18]. Such species with an enhanced activity were obtained by incorporation of Cu(II), & Rodica Olar rodica_m_olar@yahoo.com 1 Department of Inorganic Chemistry, Faculty of Chemistry, University of Bucharest, 90-92 Panduri Str., Sector 5, 050663 Bucharest, Romania 2 Institute for Control of Biological Products and Veterinary Medicines, 39 Dudului Str., Sector 6, Bucharest, Romania 3 Department of Microbiology, Faculty of Biology, University of Bucharest, 1-3 Aleea Portocalilor St., Bucharest, Romania 4 Research Institute of the University of Bucharest, Spl. Independentei 91-95, Bucharest, Romania 5 Stefan S Nicolau Institute of Virology, 285 Mihai Bravu Ave., Bucharest, Romania 6 National Institute for Materials Physics, P.O. Box MG-7, Bucharest-Magurele, Romania 123 J Therm Anal Calorim DOI 10.1007/s10973-016-5502-y