1 3 J Biol Inorg Chem DOI 10.1007/s00775-016-1428-x ORIGINAL PAPER EPR interpretation, magnetism and biological study of a Cu(II) dinuclear complex assisted by a schiff base precursor Kuheli Das 1,2 · Chiranjit Patra 1 · Chandana Sen 1 · Amitabha Datta 2 · Chiara Massera 3 · Eugenio Garribba 4 · Mohamed Salah El Fallah 5 · Belete B. Beyene 2 · Chen-Hsiung Hung 2 · Chittaranjan Sinha 1 · Tulin Askun 6 · Pinar Celikboyun 6 · Daniel Escudero 7 · Antonio Frontera 8 Received: 9 August 2016 / Accepted: 6 December 2016 © SBIC 2016 complex by DFT computation. Both the ligand and complex 1 exhibit anti-mycobacterial activity and considerable effi- cacy on M. tuberculosis H 37 Ra (ATCC 25177) and M. tuber- culosis H 37 Rv (ATCC 25618) strains. The practical appli- cability of the ligand and complex 1 has been examined in living cells (African Monkey Vero Cells). The MTT assay proves the non-toxicity of the probe up to 100 mg mL -1 . Graphical abstract A new homometallic dinuclear Cu(II) complex is afforded with a tetradentate Schiff base precur- sor. EPR interpretation and temperature dependent mag- netic studies show that complex 1 has weak antiferromag- netic coupling and DFT computation is governed to explain the magneto-structural correlation. Abstract A new Cu(II) dinuclear complex, Cu 2 L 2 (1) was afforded employing the potentially pentatentate Schiff base precursor H 2 L, a refluxed product of o-vanillin and dieth- ylenetriamine in methanol. Complex 1 was systematically characterized by FTIR, UV–Vis, emission and EPR spec- trometry. The single crystal X-ray diffraction analysis of 1 reveals that the copper atom exhibits a distorted square planar geometry, comprising two pairs of phenolato-O and imine-N donors from two different H 2 L ligands. The tem- perature dependent magnetic interpretation agrees with the existence of weak antiferromagnetic interactions between the bridging dinuclear Cu(II) ions. A considerable body of experimental evidence has been accumulated to elucidate the magneto-structural relationship in this dinuclear Cu(II) Electronic supplementary material The online version of this article (doi:10.1007/s00775-016-1428-x) contains supplementary material, which is available to authorized users. * Amitabha Datta amitd_ju@yahoo.co.in * Chen-Hsiung Hung chhung@gate.sinica.edu.tw * Chittaranjan Sinha c_r_sinha@yahoo.com 1 Department of Chemistry, Jadavpur University, Kolkata 700032, India 2 Institute of Chemistry, Academia Sinica, Nankang, Taipei 115, Taiwan 3 Dipartimento di Chimica, Universita degli Studi di Parma, Viale delle Scienze, 17/A, 43124 Parma, Italy 4 Dipartimento di Chimica e Farmacia, Università di Sassari, Via Vienna 2, 07100 Sassari, Italy 5 Departament de Química Inorgànica, Facultat de Química, Universitat de Barcelona, Martíi Franquès, 1-11, 08028 Barcelona, Catalunya, Spain 6 Department of Biology, Faculty of Sciences and Arts, University of Balikesir, Cagis Campus, 10145 Balıkesir, Turkey 7 CEISAM UMR CNRS 6230, Université de Nantes, 2 rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3, France 8 Departament de Quimica, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma de Mallorca (Baleares), Spain