Dalton Transactions PAPER Cite this: Dalton Trans., 2013, 42, 6572 Received 17th December 2012, Accepted 17th February 2013 DOI: 10.1039/c3dt33026e www.rsc.org/dalton New water-soluble polypyridine silver(I) derivatives of 1,3,5-triaza-7-phosphaadamantane (PTA) with significant antimicrobial and antiproliferative activities† Piotr Smoleński,* a Sabina W. Jaros, a Claudio Pettinari,* b Giulio Lupidi, b Luana Quassinti, b Massimo Bramucci, b Luca A. Vitali, b Dezemona Petrelli, c Andrzej Kochel a and Alexander M. Kirillov d The new series of silver(I) coordination polymers [Ag(N–N)(μ-PTA)] n (X) n (1, 2, 4–8, 10, 11) and discrete monomers [Ag(N–N)(PTA) 2 ](X) (3, 9) {N–N = bpy (1–3), dtbpy (4), neocup (5, 6), phen (7–9), dione (10, 11); X = NO 3 (1, 3, 5, 7, 9, 10), PF 6 (2, 4, 6, 8, 11)} were generated by self-assembly reactions, in MeOH at ∼25 °C, of AgNO 3 or AgPF 6 with 1,3,5-triaza-7-phosphaadamantane (PTA) and the correspond- ing polypyridines, namely 2,2’-bipyridine (bpy), 4,4’-di-tert-butyl-2,2’-bipyridine (dtbpy), 1,10-phen- anthroline (phen), 2,9-dimethyl-1,10-phenanthroline (neocup) and 1,10-phenanthroline-5,6-dione (dione). The compounds were obtained as air and light stable solids and characterized by IR, 1 H and 31 P{ 1 H} NMR spectroscopy, ESI + -MS and elemental analyses. The crystal structure of 1 was determined by single crystal X-ray diffraction analysis, revealing infinite one-dimensional (1D) linear chains driven by μ-PTA N,P-linkers. Apart from representing the first examples of the metal–PTA derivatives bearing polypyridine ligands, 1–11 also feature solubility in water (S 25°C ≈ 4–18 mg mL −1 ). Selected compounds (1, 3, 5, 7, 9 and 10) were thus tested for their biological properties and found to exhibit significant antibacterial and anti- fungal activities, screened in vitro against the standard strains of Staphylococcus aureus, Staphylococcus pyogenes, Staphylococcus pneumoniae, Staphylococcus sanguinis, Staphylococcus mutans, Enterococcus fae- calis, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. Furthermore, the compounds 5, 7, 9 and 10 show a pronounced antiproliferative activity against human malignant melanoma (A375), and the effects on the inhibition of tumor cells in vitro are in agreement with the DNA-binding studies. Introduction Silver(I) coordination compounds bearing various nitrogen- and/or phosphorus-donor ligands exhibit a wide range of appli- cations in the fields of medicinal and analytical chemistry, cata- lysis and the polymer industry. 1 In particular, the biomedical uses of Ag I compounds are related to their recognized antibacterial and antifungal actions. 2,3 The biological activity and other desirable properties (e.g., water solubility and light stability) of silver complexes can be tuned by varying the number and type of ligands coordinated to the silver atom. 1–3 Although silver complexes typically exhibit superior bioactivity in comparison with simple salts, the insolubility of Ag coordi- nation compounds in an aqueous medium limits their uses in bactericidal compositions, ointments and creams. 1,2,4 Some noteworthy examples of hydrosoluble and bioactive silver com- plexes are typically formed by functionalized carboxylate, pyridine- carboxylate and thioglycoside ligands. 4b,5 The aromatic N,N-ligands such as 2,2′-bipyridine, 1,10-phen- anthroline and their various derivatives have been a subject of intense research due to their versatile coordination chem- istry and recognized function in diverse biological systems. 6–8 In contrast to Cu–polypyridine derivatives, 9 the biological properties of the analogous silver(I) complexes have only been investigated in a few studies. 10 A series of Ag–polypyridine † CCDC 915914 (1·MeOH) contains the supplementary crystallographic data. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c3dt33026e a Faculty of Chemistry, University of Wroclaw, ul. F. Joliot-Curie 14, 50-383 Wroclaw, Poland. E-mail: piotr.smolenski@chem.uni.wroc.pl b School of Pharmacy, Università degli Studi di Camerino, via S Agostino 1, 62032 Camerino, MC, Italy. E-mail: claudio.pettinari@unicam.it c School of Biosciences and Biotechnology, Università degli Studi di Camerino, via Gentile III da Varano, 62032 Camerino, MC, Italy d Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal 6572 | Dalton Trans., 2013, 42, 6572–6581 This journal is © The Royal Society of Chemistry 2013 Published on 18 February 2013. Downloaded by University of Camerino on 19/08/2013 13:05:44. View Article Online View Journal | View Issue