A novel 2D chiral silver(I) coordination polymer assembled from 5-sulfosalicylic acid and (2S,4R)-4-hydroxyproline: Synthesis, crystal structure, HOMO–LUMO and NBO analysis

Influence of proline and hydroxyproline as antimicrobial and anticancer peptide components on the silver(I) ion activity: structural and biological evaluation with a new theoretical and experimental SAR approach

Silver(I) complexes with proline and hydroxyproline were synthesized and structurally characterized and crystal structure analysis shows that the formulas of the compounds are {[Ag2(Pro)2(NO3)]NO3}n (AgPro) (Pro = L-proline) and {[Ag2(Hyp)2(NO3)]NO3}n (AgHyp) (Hyp = trans-4-hydroxy-L-proline). Both complexes crystallize in the monoclinic lattice with space group P21 with a carboxylate bidentate-bridging coordination mode of the organic ligands Pro and Hyp (with NH2+ and COO- groups in zwitterionic form). Both complexes have a distorted seesaw (C2v) geometry around one silver(I) ion with τ4 values of 58% (AgPro) and 51% (AgHyp). Moreover, the results of spectral and thermal analyses correlate with the structural ones. 1H and 13C NMR spectra confirm the complexes species' presence in the DMSO biological testing medium and their stability in the time range of the bioassays. In addition, molar conductivity measurements indicate complexes' behaviour like 1 : 1 electrolytes. Both complexes showed higher or the same antibacterial activity against Bacillus cereus, Pseudomonas aeruginosa and Staphylococcus aureus as AgNO3 (MIC = 0.063 mM) and higher than silver(I) sulfadiazine (AgSD) (MIC > 0.5 mM) against Pseudomonas aeruginosa. In addition, complex AgPro exerted a strong cytotoxic effect against the tested MDA-MB-231 and Jurkat cancer cell lines (IC50 values equal to 3.7 and 3.0 μM, respectively) compared with AgNO3 (IC50 = 6.1 (5.7) μM) and even significantly higher selectivity than cisplatin (cisPt) against MDA-MB-231 cancer cell lines (SI = 3.05 (AgPro); 1.16 (cisPt), SI - selectivity index). The binding constants and the number of binding sites (n) of AgPro and AgHyp complexes with bovine serum albumin (BSA) were determined at four different temperatures, and the zeta potential of BSA in the presence of silver(I) complexes was also measured. The in ovo method shows the safety of the topical and intravenous application of AgPro and AgHyp. Moreover, the complexes' bioavailability was verified by lipophilicity evaluation from the experimental and theoretical points of view.

Silver(I) pyrrole- and furan-2-carboxylate complexes - From their design and characterization to antimicrobial, anticancer activity, lipophilicity and SAR

Two silver(I) complexes with biologically relevant heterocyclic ligands, pyrrole and furan-2- carboxylic acid, were synthesized and their composition was confirmed using elemental, spectral, thermal and structural analyses. The {[Ag(Py2c)]}n (AgPy2c, Py2c = pyrrole-2-carboxylate) and {[Ag(Fu2c)]}n (AgFu2c, Fu2c = furan-2-carboxylate) solubility and stability in biological test stock solution were confirmed by 1H NMR spectroscopy. The X-ray analysis has enabled us to determine typical argentophilic interactions and bridging carboxylate coordination mode of both ligands. Potentiometric data analysis by BSTAC program resulted in the determination of the stability constant of only one species, i.e., the ML (M = Ag+, L = Fu2c-), log βML = 0.59 ± 0.04. Antimicrobial and anticancer tests were performed against selected microorganisms and cell lines with new silver(I) complexes and compared with AgSD (silver(I) sulfadiazine) and cisplatin. From their microbial toxicity point of view, selectivity was determined against lactobacilli (AgPy2c is 8× more effective against S. aureus and E. coli and AgFu2c is 8× more effective against E. coli and 4× against S. aureus). AgFu2c significant anticancer activity was determined against Jurkat cell lines (IC50 = 8.00 μM) and was similar to cisPt (IC50 = 6.3 μM) similarly to its selectivity (SI (AgFu2c) = 7.3, SI (cisPt) = 6.4, SI = selectivity index). In addition, cell cycle arrest was observed already in the Sub-G0 phase during a flow cytometry experiment. To evaluate the AgPy2c and AgFu2c bioavailability we also discuss their Lipinski's Rule of Five.

A One-Dimensional Coordination Polymer Containing Cyclic [Ag4] Clusters Supported by a Hybrid Pyridine and Thioether Functionalized 1,2,3-Triazole

A pyridine and thioether co-supported triazole ligand L (L = 2-((4-(3-(cyclopentylthio)propyl)-1H-1,2,3-triazol-1-yl)methyl)pyridine) has been synthesized using the CuAAC click reaction. This ligand supports the formation of a thermally stable, one-dimensional coordination polymer [L2Ag4]n·4n(BF4) (1) possessing a cationic polymeric structure with [Ag4] metallomacrocycles, in which the ligand L displays chelate/bridging coordination modes using all four potential donors of nitrogen (N) and thioether (S). The dominant direction of the prism crystals of 1 aligns with the propagation of the chain in the lattice.

Organic-inorganic hybrid materials from divalent metal cations and expanded N,N′-donor linkers

The rod-shaped linker (E,E)-N,N′-(3,3′-dimethyl-4,4′-biphenyldiyl)bis[1-(3-pyridinyl)methanimine] (L) is exploited for the first time in the synthesis of extended structures. Four new coordination polymers of composition {[ZnL(OAc)2]·EtOH}n (1), {[CdL(OAc)2]·MeOH}n (2), {[Cu2L(OAc)4]·CH2Cl2}n (3) and [MnL(N3)2]n (4) have been structurally characterized. The metal cations and the anionic ancillary ligands play pivotal roles for the topology of these compounds. In the crystalline reaction products of Zn(II), Cd(II) and Cu(II) acetate with the organic linker, the acetate anions connects two neighboring cations to dinuclear [M2(OAc)4] subunits. These secondary building units are further crosslinked by the N,N′-donor ligand, either perpendicular to the acetato bridges, leading to a ladder-like ribbon for 1 and 2, or in the direction of the metal···metal separation, resulting in a simple chain in the case of 3. Instead of dinuclear secondary building units, a different topology results from reaction of the N,N′ linker with Mn(ClO4)2 in the presence of azide anions: 1,3 bridging by the N3 − groups leads to infinite chains. These are crosslinked by L in perpendicular direction, and the layer structure 4 is obtained. Natural bond orbital (NBO) analyses revealed information on the basis of orbital interactions about the coordination environments of the metal ions. Thermogravimetric measurements indicate the highest thermal stability for 2. Strong antiferromagnetic coupling within the dinuclear subunits of 3 is observed as a consequence of superexchange via the acetato bridges.

Silver(I) coordination polymers assembled from flexible cyclotriphosphazene ligand: structures, topologies and investigation of the counteranion effects

The reactions of a flexible ligand hexakis(3-pyridyloxy)cyclotriphosphazene (HPCP) with a variety of silver(I) salts (AgX;X= NO3−, PF6−, ClO4−, CH3PhSO3−, BF4−and CF3SO3−) afforded six silver(I) coordination polymers, namely {[Ag2(HPCP)]·(NO3)2·H2O}n(1), {[Ag2(HPCP)(CH3CN)]·(PF6)2}n(2), {[Ag2(HPCP)(CH3CN)]·(ClO4)2}n(3), [Ag3(HPCP)(CH3PhSO3)3]n(4), [Ag2(HPCP)(CH3CN)(BF4)2]n(5) and {[Ag(HPCP)]·(CF3SO3)}n(6). All of the isolated crystalline compounds were structurally determined by X-ray crystallography. Changing the counteranions in the reactions, which were conducted under similar conditions ofM/Lratio (1:1), temperature and solvent, resulted in structures with different types of topologies. In complexes (1)–(6), the ligand HPCP shows different coordination modes with AgIions giving two-dimensional layered structures and three-dimensional frameworks with different topologies. Complex (1) displays a new three-dimensional framework adopting a (3,3,6)-connected 3-nodal net with point symbol {4.62}2{42.610.83}. Complexes (2) and (3) are isomorphous and have a two-dimensional layered structure showing the same 3,6L60 topology with point symbol {4.26}2{48.66.8}. Complex (4) is a two-dimensional structure incorporating short Ag...Ag argentophilic interactions and has a uninodal 4-connectedsql/Shubnikov tetragonal plane net with {44.62} topology. Complex (5) exhibits a novel three-dimensional framework and more suprisingly contains twofold interpenetrated honeycomb-like networks, in which the single net has a trinodal (2,3,5)-connected 3-nodal net with point symbol {63.86.12}{63}{8}. Complex (6) crystallizes in a trigonal crystal system with the space group R\bar 3 and possesses a three-dimensional polymeric structure showing a binodal (4,6)-connectedfshnet with the point symbol (43.63)2.(46.66.83). The effect of the counteranions on the formation of coordination polymers is discussed in this study.

Silver(i) complexes with a P–N hybrid ligand and oxyanions: synthesis, structures, photocatalysis and photocurrent responses

Silver(i) complexes with a P–N ligand and oxyanion show excellent catalytic photodegradation performances, which correlate with their photocurrent responses.