Syntheses,Crystal Structures and Cytotoxities of Silver (I) Complexes of 2,2′‐Bipyridines and 1,10‐Phenanthroline

The syntheses, characterizations and in vitro cytotoxities of seven soluble silver (I) compounds (1–7) with 2,2′‐bipyridine (bpy), 5,5′‐dimethyl‐2,2′‐bipyridine (dmbpy) and 1, 10‐phenanthroline (phen) are described. Two of the complexes, [Ag(dmbpy)(NO₃)] (1) and [Ag(dmbpy)]ClO₄(2), have been structurally established by single‐crystal X‐ray diffraction, which reveals the silver(I) atom in compound 1 is in a Y‐shape coordination geometry with two N atoms (av. Ag? N = 227.8 pm) from a chelate dmbpy ligand and an O atom (Ag? O=221.8(4) pm) from a monodentate nitrate. The Ag(I) atom in compound 2 is three‐coordinated by three N atoms, two of which are from a chelate dmbpy, and one from an acetonitrile ligand. The seven compounds showed strong cytotoxities in vitro to both normal and carcinoma cells.     

DFT Calculations of the Elimination Kinetics of Silacyclobutanes and its Methyl Derivatives in the Gas-Phase

Abstract

The gas-phase thermal decomposition kinetics of silacyclobutane (1), 1-methyl- silacyclobutane (2), and 1,1-dimethyl-1-silacyclobutane (3) has been theoretically studied at the B3LYP/6-311G**, B3PW91/6-311G**, and MPW1PW91/6-311G** levels. The B3LYP/6-311G** method was found to give a reasonable good agreement with the experimental kinetics and thermodynamic parameters. The decomposition reaction of compounds 1–3 yields ethylene and the corresponding silene. Based on the optimized ground state geometries using B3LYP/6-311G** method, the natural bond orbital (NBO) analysis of donor-acceptor (bonding–antibonding) interactions revealed that the perturbation energies (E₂) associated with the electronic delocalization from σ_Si1–C2 to σ*_C4–Si1 orbitals increase from compounds 1 to 3. The σ_Si1–C2→σ*_C4–Si1 resonance energies for compounds 1–3 are 1.17, 1.26, and 1.43 kcal/mol, respectively. Also, the decomposition process in these compounds is controlled by σ→σ* resonance energies. Moreover, the obtained order of energy barriers could be explained by the number of electron-releasing methyl groups substituted to the Si_sp2 atom. NBO analysis shows that the occupancies of σ_Si1–C2 bonds decrease for compounds 1–3 as 3 < 2 < 1, and the occupancies of σ*_Si1–C2 bonds increase in the opposite order (3 > 2 > 1). Moreover, these results can fairly explain the decrease of the energy barriers (ΔE_o) of the decomposition reaction of compounds 1 to 3. The calculated data demonstrate that in the decomposition process of the studied compounds, the polarization of the C₃–C₄ bond is the rate determining factor. Analysis of bond orders, NBO charges, bond indexes, synchronicity parameters, and IRC calculations indicate that these reactions are occurring through a concerted and asynchronous four-membered cyclic transition state type of mechanism.     

3-乙基-2-乙酰吡嗪缩4-苯基氨基脲Ag(I)配合物的合成、结构和DNA结合性质

合成并通过单晶衍射、元素分析及红外光谱表征了配合物[Ag₂（HL）（NO₃）₂]_n（1）的结构（HL为3-乙基-2-乙酰吡嗪缩4-苯基氨基脲）。单晶衍射结果表明,配合物1中,HL作为中性四齿配体连接2个Ag（I）中心,其中一个Ag（I）中心与HL配体中的ON₂供体（羰基O,亚胺N和吡嗪N1原子）和2个单齿硝酸根配位,构成扭曲的四方锥配位构型;而另一个Ag（I）离子与1个单齿硝酸根,1个双齿硝酸根和HL配体中的吡嗪N4原子配位,形成扭曲平面正方形配位构型。另外,相邻的Ag（I）离子通过桥联的硝酸根离子相互连接形成二维层状结构;此外,配合物1与DNA的相互作用强于配体。     

DFT,solvation effects,reactivity and SERS analysis on structural,optical, and vibrational properties of a biomolecule of pyrimidine derivative adsorbed on metal clusters of Ag/Au/Cu

Density Functional Theory (DFT) computations were performed to investigate the optical properties of dihydropyrimidine (DHP) and metal clusters of copper (Cu), gold (Au), and silver (Ag). The charge transfers from the metal cluster to DHP through the NH group are revealed by molecular electrostatic potential (MEP) surface and Mulliken charge analysis. Bonding and antibonding orbitals of the DHP-adsorbed metal clusters are responsible for the surface resonance peak in the UV–Vis spectra of DHP adsorbed metal clusters. The polarizability values of DHP-adsorbed on metal clusters are very high in comparison with that of pristine DHP, which suggests an increase in the Non-linear optical (NLO) effect. Our study explores that the DHP adsorbed metal clusters could be used for the NLO materials. The vibrational modes of DHP are enhanced in the DHP adsorbed metal clusters due to surface-enhanced Raman scattering (SERS). Solvation energy is found to be ?21.01, ?29.37, and ?27.82 kcal/mol for DHP-Ag₃/Au₃/Cu₃ which means the DHP-adsorbed metal clusters are stable in thr aqueous medium. The atom in molecule-reduced density gradient (AIM-RDG) isosurface shows weak non-covalent interactions in each DHP adsorbed metal clusters.     

catena‐Poly[[silver(I)‐μ‐[9,10‐bis(1H‐benzimidazol‐1‐ylmethyl)anthracene]‐κ2N3:N3′] bis(nitrato‐κO)silver(I)]

Yellow needle‐shaped crystals of the title compound, {[Ag(C₃₀H₂₂N₄)][Ag(NO₃)₂]}_n, were obtained by the reaction of AgNO₃ and 9,10‐bis(benzimidazol‐1‐ylmethyl)anthracene (L) in a 2:1 ratio. The asymmetric unit consists of two Ag^I cations, one half L ligand and one nitrate anion. One Ag^I cation occupies a crystallographic inversion centre and links two N‐atom donors of two distinct L ligands to form an infinite one‐dimensional coordination polymer. The second Ag^I cation lies on a crystallographic twofold axis and is coordinated by two O‐atom donors of two nitrate anions to form an [Ag(NO₃)₂]⁻ counter‐ion. The polymeric chains are linked into a supramolecular framework via weak Ag...O [3.124 (5) Å] and Ag...π (2.982 Å) interactions (π is the centroid of an outer anthracene benzene ring). The π interactions contain two short Ag...C contacts [2.727 (6) and 2.765 (6) Å], which can be considered to define Ag–η²‐anthracene bonding interactions. In comparison with a previously reported binuclear Ag^I complex [Du, Hu, Zhang, Zeng & Bu (2008). CrystEngComm, 10 , 1866–1874], this new one‐dimensional coordination polymer was obtained by changing the metal–ligand ratio during the synthesis.     

Silver(I) complexes with halo-substituted cyanoanilines: synthesis,characterization and antibacterial activity

Four Ag(I) complexes, [Ag(L₁)₂](NO₃) (1), [Ag(L₂)(NO₃)] (2), [Ag(L₃)₃](NO₃) (3), and [Ag(L₄)₂](NO₃) (4), with ligands derived from halo-containing cyanoanilines (L₁ = 4-amino-3fluorobenzonitrile, L₂ = 4-amino-3-chlorobenzonitrile, L₃ = 4-amino-3-bromobenzonitrile, L₄ = 4-amino-2-bromobenzonitrile) were synthesized and characterized by C, H, and N elemental analysis, IR and ¹H NMR spectroscopy and single crystal X-ray diffraction. Complexes 1–4 crystallized in the triclinic space group C2/c, P2(1)/n, P-1 and C2/c, respectively. In 1 and 4, Ag⁺ is four-coordinate with L₁ or L₄ to form 1-D _∞{[Ag(L₁/L₄)₂]⁺} polymeric cations. In 2, Ag⁺ is three-coordinate by two L₂ ligands and one NO₃^? ligand to form a 1-D _∞{[Ag(L₂)(NO₃)]} zigzag chain. In 3, Ag⁺ is four-coordinate by L₃ to form a dinuclear [Ag(L₃)₃]⁺ cation. The NO₃^? is a 4-connector bridging group in 1 and 3 and a 5-connector bridging group in 2 and 4. The intermolecular hydrogen bonds and Ag?O weak interactions play important roles in forming 3-D networks of 1–4. The antibacterial activities for 1–4 were evaluated against Bacillus subtilis, Staphylococcus aureus and Escherichia coli with MTT method. The antibacterial results indicated that 2 showed the best inhibitory activity against the test bacterial strains, and was as potent as chloramphenicol.     

A Coordination Polymer from HAMTTO with Silver(I) (HAMTTO = 4‐Amino‐6‐methyl‐1,2,4‐triazine‐3‐thione‐5‐one)

The reaction of 4‐amino‐6‐methyl‐1,2,4‐triazine‐3‐thione‐5‐one, HAMTTO, with silver (I) nitrate in methanol led under deprotonation to the polymeric compound [(AMTTO)Ag]_n. The coordination polymer {[Ag(HAMTTO)]ClO₄}_n ( 1 ) is synthesized from the reaction of the latter polymeric compound with perchloric acid. Both compounds were characterized by elemental analysis and IR spectroscopy. Single‐crystal X‐ray diffraction studies on compound 1 showed that HAMTTO acts as a bidentate ligand and chelates the silver atom via its hydrazine nitrogen atom and its sulfur atom. Crystal data for 1 at ?90 °C: space group P2₁, Z = 2, a = 629.3(1), b = 748.7(1), c = 1071.7(1) pm, β = 98.28(1)°, R₁ = 0.0533.     

Synthesis,characterization, and antimicrobial activity of two Schiff base silver(I) complexes derived from 4-carboxybenzaldehyde

Two new Schiff base silver(I) complexes, {[Ag(L¹)][H₂O]}_∞ (1) and {[Ag(L²)][H₂O]}_∞ (2), where L¹ = 4-((2-diethylaminoethylimino)methyl)phenecarboxylate and L² = 4-([3-(morpholin-4-yl)propyl]iminomethyl)phenecarboxylate, have been synthesized and characterized. X-ray crystallographic analysis reveals that silver ions in 1 are bridged by L¹ to form a one-dimensional zigzag chain, while three silver ions in 2 are linked by L² to produce a two-dimensional coordination polymer. Guest water molecules in 1 generate a one-dimensional hydrogen-bonded chain. Both 1 and 2 offer high antibacterial activity against Gram-positive bacteria Staphylococcus aureus with MIC values of 0.26 and 0.24 mM and to exhibit good inhibitory activity against urease with the respective IC₅₀ values of 3.5 ± 0.1 and 3.8 ± 0.2 μM.     

Silver(I) and mercury(II) complexes with N,N′-bis(acetylacetone)-1R,2R-diaminocyclohexane ligands exhibiting three different coordination modes

Treatment of AgNO₃ with one equiv. of N,N′-bis(acetylacetone)-1R,2R-diaminocyclohexane (L) afforded a mononuclear complex [Ag(η²-L)NO₃] (1) in which the central silver(I) atom adopts a distorted trigonal planar geometry by coordinating two carbon atoms of the methane moieties of the ligand and one oxygen atom of the NO₃^? group. Interaction of CF₃COOAg with one equiv. of L produced a one-dimensional coordination polymer [Ag₂(μ-L)(CF₃CO₂)₂]_n (2). Each silver(I) in 2 exhibits highly distorted square planar coordination geometry that connects one oxygen atom of L and one neighboring Ag atom with the Ag?Ag interactions. Reaction of HgCl₂ with one equiv. of L resulted in the formation of one-dimensional [{Hg(μ-Cl)Cl}₂(μ-η¹-L)]_n (3) with a C-coordinated dinuclear mercury(II) chloride moiety being linked by L.     

A 3D Polyoxometalate‐Based Framework Constructed from Ag/trz Metal‐Organic Ribbons and P2W18 Polyoxoanions: Synthesis,Structure and Electrochemical Properties

A Wells‐Dawson Polyoxometalate‐based hybrid, Ag₉(trz)₃(Htrz)₄ (H₂O)(P₂W₁₈O₆₂)·3H₂O ( 1 ) (Htrz = 1,2,4‐1H‐triazole) was hydrothermally synthesized through using trz ligand and silver nitrate in the presence of [P₂W₁₈O₆₂]^6– polyoxoanion. In the 3D framework structure of compound 1 , two kinds of wave‐like Ag/trz chains originated from trz ligands and silver cations are aggregated in a “2+1” mode by {Ag₂/trz} linkages to result in a 1D Ag/trz metal‐organic ribbon, which is further extended into a 3D framework structure by [P₂W₁₈O₆₂]^6– polyoxoanions through Ag‐O covalent bonds. Additionally, the electrochemical properties of compound 1 have also been investigated.     

A novel one‐dimensional silver cylinder stabilized by mixed 2‐mercaptobenzoic acid and ethylenediamine ligands

A novel infinite one‐dimensional silver cylinder, namely poly[μ‐ethylenediamine‐μ₅‐(2‐sulfanidylbenzoato)‐μ₄‐(2‐sulfanidylbenzoato)‐tetrasilver(I)], [Ag₄(C₇H₄O₂S)₂(C₂H₈N₂)]_n, has been synthesized by one‐pot reaction of equivalent molar silver nitrate and 2‐mercaptobenzoic acid (H₂mba) in the presence of ethylenediamine (eda). One Ag atom is located in an AgS₂NO four‐coordinated tetrahedral geometry, two other Ag atoms are in an AgS₂O three‐coordinated T‐shaped geometry and the fourth Ag atom is in an AgSNO coordination environment. The two mba ligands show two different binding modes. The μ₂‐N:N′‐eda ligand, acting as a bridge, combines with mba ligands to extend the Ag^I ions into a one‐dimensional silver cylinder incorporating abundant Ag...Ag interactions ranging from 2.9298 (11) to 3.2165 (13) Å. Interchain N—H...O hydrogen bonds extend the one‐dimensional cylinder into an undulating two‐dimensional sheet, which is further packed into a three‐dimensional supramolecular framework by van der Waals interactions; no π–π interactions were observed in the crystal structure.     

Comparative analysis of blue‐shifted hydrogen bond versus conventional hydrogen bond in methyl radical complexes

Methyl radical complexes H₃C…HCN and H₃C…HNC have been investigated at the UMP2(full)/aug‐cc‐pVTZ level to elucidate the nature of hydrogen bonds. To better understand the intermolecular H‐bond interactions, topological analysis of electron density at bond critical points (BCP) is executed using Bader's atoms‐in‐molecules (AIM) theory. Natural bond orbital (NBO) analysis has also been performed to study the orbital interactions and change of hybridization. Theoretical calculations show that there is no essential difference between the blue‐shift H‐bond and the conventional one. In H₃C…HNC complex, rehybridization is responsible for shortening of the N? H bond. The hyperconjugative interaction between the single electron of the methyl radical and N? H antibonding orbital is up to 7.0 kcal/mol, exceeding 3.0 kcal/mol, the upper limit of hyperconjugative n(Y)→σ*(X–H) interaction to form the blue‐shifted H‐bond according to Alabugin's theory. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

catena‐Poly­[[(di‐2‐pyridyl­amine)­silver(I)]‐μ‐nicotinato] and catena‐poly­[[(di‐2‐pyridyl­amine)silver(I)]‐μ‐2,6‐di­hydroxy­benzoato]

In catena‐poly­[[(di‐2‐pyridyl­amine‐κ²N,N′)silver(I)]‐μ‐nico­tinato‐κ²N:O], [Ag(C₆H₄NO₂)(C₁₀H₉N₃)]_n, the Ag^I atom is tetracoordinated by two N atoms from the di‐2‐pyridyl­amine (BPA) ligand [Ag—N = 2.3785 (18) and 2.3298 (18) Å] and by one N atom and one carboxyl­ate O atom from nicotinate ligands [Ag—N = 2.2827 (15) Å and Ag—O = 2.3636 (14) Å]. Bridging by nicotinate N and O atoms generates a polymeric chain structure, which extends along [100]. The carboxyl O atom not bonded to the Ag atom takes part in an intrachain C—H⋯O hydrogen bond, further stabilizing the chain. Pairs of chains are linked by N—H⋯O hydrogen bonds to generate ribbons. There are no π–π interactions in this complex. In catena‐poly­[[(di‐2‐pyridyl­amine‐κ²N,N′)silver(I)]‐μ‐2,6‐di­hydroxy­benzoato‐κ²O¹:O²], [Ag(C₇H₅O₄)(C₁₀H₉N₃)]_n, the Ag^I atom has a distorted tetrahedral coordination, with three strong bonds to two pyridine N atoms from the BPA ligand [Ag—N = 2.286 (5) and 2.320 (5) Å] and to one carboxyl­ate O atom from the 2,6‐di­hydroxy­benzoate ligand [Ag—O = 2.222 (4) Å]; the fourth, weaker, Ag‐atom coordination is to one of the phenol O atoms [Ag⋯O = 2.703 (4) Å] of an adjacent moiety, and this interaction generates a polymeric chain along [100]. Pairs of chains are linked about inversion centers by N—H⋯O hydrogen bonds to form ribbons, within which there are π–π interactions. The ribbons are linked about inversion centers by pairs of C—H⋯O hydrogen bonds and additional π–π interactions between inversion‐related pairs of 2,6‐di­hydroxy­benzoate ligands to generate a three‐dimensional network.     

Silver(I) 3-D-supramolecular coordination frameworks constructed by the combination of coordination bonds and supramolecular interactions

Room temperature reactions of the ternary adducts of AgNO₃, bipodal ligand [4,4′-bipyridine (4,4′-bpy) or trans-1,2-bis(4-pyridyl)ethylene (tbpe) or 1,2-bis(4-pyridyl)ethane (bpe)] and organic ligand [4-aminobenzoic acid (4-aba) or 4-hydroxybenzoic acid (4-hba) or terephthalate ion (tph)] afford new 3-D supramolecular coordination polymers (SCPs), namely, {[Ag(4,4′-bpy) · H₂O](4-ab) · 2H₂O} (1), {[Ag(tbpe)]0.5(4-hb) · 3H₂O} (2), [Ag₂(L)₂ · (tph)] (L = 4,4′-bpy, tbpe) (3,4) and {[Ag₂(bpe)₂ · (tph)] · 2H₂O} (5). The bipodal ligand coordinates to silver forming a 1-D cationic chain (A), while the organic ligand and solvent form a 1-D anionic chain (B) via hydrogen bonds. The chains construct layers which are connected via hydrogen bonds and π–π stacking forming a 3-D network structure. The presence of the carboxylate, amino and hydroxyl groups in the organic ligands significantly extend the dimensionality via hydrogen bonds. All the SCPs 1–5 exhibit strong luminescence.     

Synthesis,characterization, and crystal structure determination of palladacycles of para-substituted 2-thiobenzylazobenzenes

Bichelated neutral palladacycles (1–3), [Pd(L)Cl], were synthesized from reaction of the new potential tridentate (C,N,S) ligands, 2-thiobenzylazobenzene (L₁), 4′-methyl-2-thiobenzylazobenzene (L₂), and 4′-chloro-2-thiobenzylazobenzene (L₃) with sodium tetrachloropalladate(II), Na₂[PdCl₄], in ethanol. The compounds were characterized by elemental analysis, FT-IR, ¹H NMR, UV–visible, and thermogravimetric analysis. The crystal structures of L₂ and 1–3 were determined by single-crystal X-ray diffraction. In 1–3, the geometry around palladium remains almost square planar, coordinated to carbon, nitrogen, and sulfur of the ligand forming a bichelated cyclopalladate complex. The C–H…Cl type intermolecular hydrogen bonds, weak π…π, C–H…π, and van der Waals interactions are believed to be the stabilizing forces for the crystal packing of these palladacycles.     

Synthesis,crystal structure and studies on the interaction with albumin of a new silver(I) complex based on 2‐(4‐nitrobenzenesulfonamido)benzoic acid

In the present work, the two‐dimensional (2D) polymer poly[[μ₄‐2‐(4‐nitrobenzenesulfonamido)benzoato‐κ⁴O¹:O¹:O^1′:N⁶]silver(I)] (AgL), [Ag(C₁₃H₉N₂O₆S)]_n, was obtained from 2‐(4‐nitrobenzenesulfonamido)benzoic acid (HL), C₁₃H₁₀N₂O₆S. FT–IR, ¹H and ¹³C{¹H} NMR spectroscopic analyses were used to characterize both compounds. The crystal structures of HL and AgL were determined by single‐crystal X‐ray diffraction. In the structure of HL, O—H…O hydrogen bonds between neighbouring molecules result in the formation of dimers, while the silver(I) complex shows polymerization associated with the O atoms of three distinct deprotonated ligands (L^?). Thus, the structure of the Ag complex can be considered as a coordination polymer consisting of a one‐dimensional linear chain, constructed by carboxylate bridging groups, running parallel to the b axis. Neighbouring polymeric chains are further bridged by Ag—C monohapto contacts, resulting in a 2D framework. Fingerprint analysis of the Hirshfeld surfaces show that O…H/H…O hydrogen bonds are responsible for the most significant contacts in the crystal packing of HL and AgL, followed by the H…H and O…C/C…O interactions. The Ag…Ag, Ag…O/O…Ag and Ag…C/C…Ag interactions in the Hirshfeld surface represent 12.1% of the total interactions in the crystal packing. Studies of the interactions of the compounds with human serum albumin (HSA) indicated that both HL and AgL interact with HSA.     

Crystal structure of a silver(I) complex {[Ag(N-methylthiourea)2]NO3}n exhibiting infinite chains of AgS4 tetrahedra

A polymeric silver(I) complex, bis(N-methylthiourea)silver(I) nitrate, {[Ag(Metu)₂]NO₃} _n is prepared and its crystal structure is determined. The compound crystallizes in the monoclinic C2/c space group. In the structure, distorted AgS₄ tetrahedra are linked through the sulfur atoms of the Metu ligand to form isolated infinite chains of the type [Ag(SR)₂] _n ⁿ⁺. The cationic chains are separated from each other by nitrate ions that do not coordinate to the metal ion. The chains are bridged via N-H...O hydrogen bonds involving the nitrate ions. The complex exhibits an Ag—Ag separation of ∼3.21 ? indicating the existence of significant argentophilic interactions. An upfield shift in the >C=S resonance of Metu in ¹³C NMR and downfield shift in the N-H resonance in ¹H NMR are consistent with sulfur coordination to silver(I).     

Catalytic activation of nitrobenzene on PVP passivated silver cluster: A DFT investigation

Poly(N‐vinyl‐2‐pyrrolidone) (PVP) has been used extensively to stabilize the surface of noble metal nanoparticles against aggregation and also to produce anisotropic nanostructures. Naturally, it is very important to understand the effect of such surface stabilization by PVP on the catalytic activity of these nanoparticles. This communication investigates through DFT calculations the electronic properties of PVP stabilized 13‐atom Ag cluster for catalytic activation of nitrobenzene (NB). These computations suggest that poly(N‐vinyl‐2‐pyrrolidone) (PVP) interact with silver (Ag) cluster mainly through oxygen atom and acts not only as a stabilizer to prevent the aggregation of Ag clusters but also as an electron donor to activate the Ag clusters for further reaction. Natural Bonding Orbital (NBO) calculations show that catalytic activation of NB by PVP passivated Ag cluster occurs due to interaction of the oxygen of the nitro group with the Ag cluster. Weak back donation of electrons from M(dπ) orbital of Ag to antibonding σ* of one of the N O bond, facilitates the formation of the nitroso intermediate. To understand the extent and the nature of this interaction better, vibrational frequency calculation of nitrobenzene association with Ag13‐2PVP cluster is carried out. Red shift in the frequencies is consequence of strong interaction with that of silver cluster present in Ag13‐2PVP‐NB model.     

Coordination-driven synthesis of Ag(I) compounds based on a double emission ligand consisting of 1,3,4-oxadiazole and cyclotriphosphazene units

A new ligand (L) which consists of cyclotriphosphazene and 1,3,4-oxadiazole units is reported. Two new Ag(I) coordination compounds {[Ag(L)SO₃CF₃] _n (1) and Ag₂L₂(NO₃)₂ (2)} based on L and Ag(I) salts are obtained. Compound 1 features a 1-D chain, in which the ligand L adopts a divergent trans-conformation, whereas 2 is a discrete binuclear Ag(I) molecule in which L adopts convergent cis-conformation. Compounds 1 and 2 are fully characterized by ¹H-NMR, Infrared, elemental analysis, X-ray powder, and single-crystal diffraction. Luminescent properties of 1 and 2 are investigated.     

Mono- and penta-nuclear self-assembled silver(I) complexes of pyrazolyl s-triazine ligand; synthesis,structure and antimicrobial studies

The self-assembled [Ag (PTDM)NO₃] ( 1 ), [Ag (PTDM)₂(H₂O)]ClO₄^.H₂O ( 2 ) and [Ag₅(PTDM)₄(H₂O)₆(ClO₄)₄]ClO₄^.2H₂O ( 3 ) complexes were synthesized by the direct mixing of AgX (X = NO₃¯ or ClO₄¯) and 4,4′-[6-(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazine-2,4-diyl]dimorpholine ( PTDM ) ligand in water–methanol mixture. The coordination numbers of silver range from three to five. Complex 3 is a rare case in which one nitrogen atom from the same s-triazine core of the PTDM ligand has a μ(1,1) bridging mode between Ag1 and Ag2 in the penta-nuclear array with Ag1–N1 and Ag2–N1 distances of 2.666(4) and 2.418(3) Å, respectively. Its 3D topology has a kind of primitive dense packing derived from the α-Po type structure. Hirshfeld analysis showed that the percentages of the O^…H hydrogen bonds were 32.4, 25.4, and 42.0% in complexes 1 – 3 , respectively. While the ligand showed no antimicrobial activity at the applicable concentration, the penta-nuclear complex 3 had higher antibacterial (MIC = 3.7 μmol/L) and antifungal (14.6 μmol/L) potencies toward the tested microbes compared with complexes 1 and 2 . Also, the killing doses of 3 were in the range of 7.3–58.5 μmol/L compared with 18.2–291.1 and 20.1–160.6 μmol/L for 1 and 2 , respectively. It is clear that the higher Ag-content in 3 could be the main reason for its higher antimicrobial activity.