The influence of protonation on molecular structure and physico-chemical properties of gossypol Schiff bases

Protonation of gossypol Schiff bases (S1 and S2), possessing different numbers of basic N-atoms, was studied using potentiometric, spectroscopic, ESI MS and PM5 methods. Titration of S1 and S2 with HClO(4), monitored by the FT-IR and (1)H NMR, indicated that the change from the enamine-enamine into the protonated imine-imine tautomeric form occurs at different Schiff base-H(+) ratio. The FT-IR and PM5 results show that for S1 the first protonation step occurs at Schiff base moiety whereas for S2 it is realised at N-atom of the morpholine. The formation of N(+)-HO hydrogen bond between morpholine moieties within S2 contributes to high pK(a(ACN)) = 22.65.     

Luminescent homochiral silver(I) lamellar coordination networks built from helical chains

The reactions of 2,2'-dimethoxy-1,1'-binaphthyl-3,3'-bis(4-vinylpyridine)(L) with AgNO3 or AgClO4 at 70 degrees C gave rise to two novel luminescent homochiral lamellar coordination polymers, AgL2X (X = NO3- for 1 or ClO4- for 2), which are built from linking helical chains by Ag(I) atoms as hinges.     

Complexes of Schiff base of gossypol with n-butylamine and some monovalent or bivalent cations studied by ESI MS, NMR, FT-IR as well as PM5 semiempirical methods

A Schiff base of gossypol with n-butylamine [GSBN] was shown to be capable of complexation of 2H⁺, Li⁺, Ca²⁺ and Ba²⁺ cations. This process of complex formation was studied by ESI mass spectrometry, ¹H and ¹³C NMR and FT-IR spectroscopy as well as by PM5 semiempirical method. It was found that gossypol Schiff base can form a 1:2 complex with H⁺ and 1:1 complexes with Li⁺, Ca²⁺ and Ba²⁺ cations. In all complexes the Schiff base of gossypol with metal cations exists in enamine-enamine tautomer, whereas in the 1:2 complex with H⁺ the imine-imine tautomer was found. The metal cations are coordinated through oxygen atoms of the O₁H(O₁,H) hydroxyl groups and a lone pair of an N-atom. The structures of these complexes were calculated by PM5 semiempirical method and discussed.     

Taurine as a ligand. An investigation of Ag(I)- and Cd(II)-taurine complex equilibria by direct and competitive techniques, and use of the Ag(I)-taurine complex electrode to assess taurine in solution

The behaviour of taurine as a ligand (L) towards silver(I) and cadmium(II) was studied at 25 degrees C and in 1 mol dm(-3) NaClO(4), as a constant ionic medium. Experimental data, obtained for both cations from electromotive force measurements performed by using silver and cadmium amalgam and glass electrodes, were explained by assuming the formation of the AgL, AgL(2), CdL, and CdL(2) complexes. The taurine protonation constant and stability constants of the above complexes were determined. The cadmium(II)-taurine system was investigated by determining the free concentration of taurine from the Ag electrode potential and the knowledge of equilibria existing between silver(I) and taurine. Experimental data obtained from this approach were explained by assuming the presence of the above species with very close stability constant values. The success of this method supports the possibility of using the Ag/Ag-taurine, taurine electrode to measure the free concentration of taurine in its solutions.     

Adjusting the frameworks of silver(I) complexes with new pyridyl thioethers by varying the chain lengths of ligand spacers, solvents, and counteranions

In our efforts to systematically investigate the effects of the linker units of flexible ligands and other factors on the structures of Ag(I) complexes with thioethers, five new flexible pyridyl thioether ligands, bis(2-pyridylthio)methane (L(1)()), 1,3-bis(2-pyridylthio)propane (L(3)()), 1,4-bis(2-pyridylthio)butane (L(4)), 1,5-bis(2-pyridylthio)pentane (L(5)), and 1,6-bis(2-pyridylthio)hexane (L(6)), have been designed and synthesized, and the reactions of these ligands with Ag(I) salts under varied conditions (varying the solvents and counteranions) lead to the formation of eight novel metal-organic coordination architectures from di- and trinuclear species to two-dimensional networks: [Ag(3)(L(1)())(2)(ClO(4))(2)](ClO(4)) (1), [[AgL(3)](ClO(4))]( infinity ) (2), [[Ag(2)(L(4))(2)](ClO(4))(2)(CHCl(3))]( infinity ) (3), [[AgL(4)](ClO(4))(C(3)H(6)O)]( infinity ) (4), [[Ag(2)L(4)](NO(3))(2)]( infinity ) (5), [Ag(2)L(4)()(CF(3)SO(3))(2)]( infinity ) (6), [[AgL(5)](ClO(4))(CHCl(3))](2) (7), and [[AgL(6)()](ClO(4))]( infinity ) (8). All the structures were established by single-crystal X-ray diffraction analysis. The coordination modes of these ligands were found to vary from N,N-bidentate to N,N,S-tridentate to N,N,S,S-tetradentate modes, while the Ag(I) centers adopt two-, three-, or four-coordination geometries with different coordination environments. The structural differences of 1, 2, 3, 7, and 8 indicate that the subtle variations on the spacer units can greatly affect the coordination modes of the terminal pyridylsulfanyl groups and the coordination geometries of Ag(I) ions. The structural differences of 3 and 4 indicate that solvents also have great influence on the structures of Ag(I) complexes, and the differences between 3, 5, and 6 show counteranion effects in polymerization of Ag(I) complexes. The influences of counterions and solvents on the frameworks of these complexes are probably based upon the flexibility of ligands and the wide coordination geometries of Ag(I) ions. The results of this study indicate that the frameworks of the Ag(I) complexes with pyridyl dithioethers could be adjusted by ligand modifications and variations of the complex formation conditions.     

Characterization of ceramic ion-selective membrane-electrodes-I The Ag(2)S electrode

The behaviour of a new type of electrode, made from ceramic Ag(2)S, has been investigated. The electrode response is Nernstian for Ag(+) over the range 10(-6)-2M and for Hg(2+) in the concentration range 10(-6)-10(-2)M, both at constant ionic strength (0.1M). The electrode is Ag(+)-selective, with maximum interference from Hg(2+). It can be used for acid-base potentiometric titration and for potentiometric Ag(+) and Hg(2+) precipitation titrations.     

Ag(Ⅰ) Schiff碱配合物的合成及其晶体结构

本文以2-醛基吡啶和1,2-二(对氨基苯氧基)乙烷进行缩合得到Schiff碱配体L,再分别同AgNO3和AgClO4进行配位反应,得到了2个配合物[Ag2(NO3)2L](1)和{[AgL]ClO4}n(2),并用元素分析,FTIR和X-射线单晶衍射进行了表征。结果表明,配合物1属于单斜晶系,P21/c空间群,Ag(I)的配位环境为平面三角形,配体L同时和2个Ag(Ⅰ)离子配位形成双核配合物。配合物2属于单斜晶系,P21/n空间群,每个Ag(Ⅰ)的配位环境均为扭曲四面体,每个配体L通过其两端的2个氮原子同2个金属离子配位桥联形成一维螺旋链结构。     

Complexation behaviour and stability of Schiff bases in aqueous solution. The case of an acyclic diimino(amino) diphenol and its reduced triamine derivative

The copper(II), nickel(II), and zinc(II) complexes of the acyclic Schiff base H(2)L(A), obtained by [1 + 2] condensation of 1,2-ethanediamine,N-(2-aminoethyl)-N-methyl with 3-ethoxy-2-hydroxybenzaldehyde, and of H(2)L(B), the reduced derivative of H(2)L(A), were prepared and their properties studied by IR, NMR and SEM-EDS. In these complexes, the metal ion is always located in the coordination chamber of the ligand delimited by two phenol oxygens and nitrogen atoms (either aminic or iminic). The coordination behaviour of H(2)L(A) and H(2)L(B) towards H(+), Cu(2+), Ni(2+) and Zn(2+) in aqueous solution at 298 K and mu = 0.1 mol dm(-3) (Na)ClO(4) was also studied by potentiometric, NMR and UV-VIS measurements. In particular, potentiometric equilibrium studies indicate that H(2)L(A) is not stable enough to have a pH range in which it is the sole species in aqueous solution. In such a solution, the Schiff base forms over a limited pH range, between 6 and 10, with a maximum formation percentage at pH approximately 9. In addition, the involvement of imine nitrogens in the complexes markedly stabilises the azomethylene linkage, so that the metal complexes of H(2)L(A), particularly those of copper(II), are the species largely prevailing in solutions with pH >3.5. The stability constants of the complexes formed by metal ions with H(2)L(A) and H(2)L(B) follow the order Cu(2+) > Ni(2+) > Zn(2+); distribution plots show that copper(II) gives complexes more stable with H(2)L(A), whereas Ni(2+) and Zn(2+) prefer the reduced ligand, H(2)L(B).     

Polymeric silver(I) complexes with pyridyl dithioether ligands: experimental and theoretical investigations on the coordination properties of the ligands

The reactions of four flexible tetradentate ligands, 1,3-bis(2-pyridylthio)propane (L1), 1,4-bis(2-pyridylthio)butane (L2), 1,5-bis(2-pyridylthio)pentane (L3) and 1,6-bis(2-pyridylthio)hexane (L4) with AgX (X = BF4-, ClO4-, PF6-, or CF3SO3-) lead to the formation of seven new complexes: [AgL1(BF4)]2 (1), [[AgL2](ClO4)]infinity (2), [[AgL2(CH3CN)](PF6)]infinity (3), [[AgL3](BF4)(CHCl3)]2 (4), [[AgL3(CF3SO3)](CH3OH)(0.5)]infinity (5), [[Ag2L4(2)](BF4)2]infinity (6), and [[AgL4](PF6)]infinity (7), which have been characterized by elemental analyses, IR spectroscopy, and X-ray crystallography. Single-crystal X-ray analyses show that complexes 1 and 4 possess dinuclear macrometallacyclic structures, and complexes 2, 3 and 5-7 take chain structures. In all the complexes, the nitrogen atoms of ligands preferentially coordinate to silver atoms to form normal coordination bonds, while the sulfur atoms only show weak interactions with silver atoms and the intermolecular AgS weak contacts connect the low-dimensional complexes into high-dimensional supramolecular networks. Additional weak interactions, such as pi-pi stacking, F...F weak interactions, Ag...O contacts or C-H...O hydrogen bonds, also help to stabilize the crystal structures. It was found that the parity of the -(CH2)n- spacers (n = 3-6) affect the orientation of the two terminal pyridyl rings, thereby significantly influence the framework formations of these complexes. The coordination features of ligands and their conformation changes between free and coordination states have been investigated by DFT calculations.     

Synthesis, structure, DNA-binding properties and antioxidant activity of silver(I) complexes containing V-shaped bis-benzimidazole ligands

A V-shaped ligand bis(2-benzimidazol-2-ylmethyl)benzylamine L(1) with its two derivatives bis(N-methylbenzimidazol-2-ylmethyl)benzylamine L(2) and bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine L(3) have been prepared. Reaction of these shape-specific designed ligands with Ag(pic) (pic = picrate) afforded three novel complexes, namely, [Ag(2)L(1)(2)](pic)(2)1, [Ag(2)L(2)(2)](pic)(2)·2DMF 2 and [AgL(3)(pic)] 3. The ligands and complexes were characterized on the basis of elemental analysis, UV-Vis, IR, NMR spectroscopy and X-ray crystallography. Complex 1 is a dinuclear metallacycle with a 2-fold rotational symmetry in which two syn-conformational L(1) ligands are connected by two linearly coordinated Ag(I) atoms. Due to the strong interaction between two adjacent Ag(I) atoms, the coordination mode of the central Ag(I) atom can be described as T-shaped. Complex 2 consists of a centrosymmetric dinuclear pore canal structure assembled from two nearly linearly coordinated Ag(I) atoms and two L(2) ligands. The structure of complex 3 adopts a four-coordinate environment for AgN(2)O(2), with the counterion participating in an eight-shaped geometry. In order to explore the relationship between the structure and biological properties, the DNA-binding properties have been investigated by viscosity measurements, electronic absorption, and fluorescence. The results suggest that the ligands and complexes bind to DNA in an intercalation mode, and their binding affinities for DNA are also different. Moreover, the three Ag(I) complexes also exhibited potential antioxidant properties in vitro studies.     

Syntheses, X-ray crystal structures, and magnetic properties of novel linear M2[II]U[IV] complexes (M=Co, Ni, Cu, Zn)

Attempts to prepare heterobimetallic complexes in which 3d and uranium magnetic ions are associated by means of the Schiff bases H(2)L(i) derived from 2-hydroxybenzaldehyde or 2-hydroxy-3-methoxybenzaldehyde were unsuccessful because of ligand transfer reactions between [ML(i)] (M=Co, Ni, Cu) and UCl(4) that led to the mononuclear Schiff base complexes of uranium [UL(i)Cl(2)]. The crystal structure of [UL(3)Cl(2)(py)(2)] [L(3)=N,N'-bis(3-methoxysalicylidene)-ethylenediamine; py=pyridine] was determined. The hexadentate Schiff base ligand N,N'-bis(3-hydroxysalicylidene)-2,2-dimethyl-1,3-propanediamine (L) was useful for the synthesis of novel trinuclear complexes of the general formula [[ML(py)](2)U] (M=Co, Ni, Zn) or [[CuL(py)]M'[CuL]] (M'=U, Th, Zr) by reaction of [M(H(2)L)] with [M'(acac)(4)] (acac=MeCOCHCOMe). The crystal structures of the Co(2)U, Ni(2)U, Zn(2)U, Cu(2)U, and Cu(2)Th complexes show that the two ML fragments are orthogonal, being linked to the central actinide ion by the two pairs of oxygen atoms of the Schiff base ligand. In each compound, the UO(8) core exhibits the same dodecahedral geometry, and the three metals are linear. The magnetic study indicated that the two Cu(2+) ions are not coupled in the Cu(2)Zr and Cu(2)Th compounds. The magnetic behavior of the Co(2)U, Ni(2)U, and Cu(2)U complexes was compared with that of the Zn(2)U derivative, in which the paramagnetic 3d ion was replaced with the diamagnetic Zn(2+) ion. A weak antiferromagnetic coupling was observed between the Ni(2+) and the U(4+) ions, while a ferromagnetic interaction was revealed between the Cu(2+) and U(4+) ions.     

Synthesis, spectral, thermal and magnetic studies of Mn(II), Ni(II) and Cu(II) complexes with some benzopyran-4-one Schiff bases

The Schiff bases of N(2)O(2) dibasic ligands, H(2)La and H(2)Lb are prepared by the condensation of ethylenediamine (a) and trimethylenediamine (b) with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one. Also tetra basic ligands, H(4)La and H(4)Lb are prepared by the condensation of aliphatic amines (a) and (b) with 6-formyl-5,7-dihydroxy-2-methylbenzopyran-4-one. New complexes of H(4)La and H(4)Lb with metal ions Mn(II), Ni(II) and Cu(II) are synthesized, in addition Mn(II) complexes with ligands H(2)La and H(2)Lb are also synthesized. Elemental and thermal analyses, infrared, ultraviolet-visible as well as conductivity and magnetic susceptibility measurements are used to elucidate the structure of the newly prepared metal complexes. The structures of copper(II) complexes are also assigned based upon ESR spectra study. All the complexes separated with the stoichiometric ratio (1:1) (M:L) except Mn-H(4)La and Mn-H(4)Lb with (2:1) (M:L) molar ratio. In metal chelates of the type 1:1 (M:L), the Schiff bases behave as a dinegative N(2)O(2) tetradentate ligands. Moreover in 2:1 (M:L) complexes, the Schiff base molecules act as mono negative bidentate ligand and binuclear complex is then formed. The Schiff bases were assayed by the disc diffusion method for antibacterial activity against Staphylococcus aureus and Escherichia coli. The antifungal activity of the Schiff bases was also evaluated against the fungi Aspergillus flavus and Candida albicans.     

A study of C-F...M(+) interaction: metal complexes of fluorine-containing cage compounds

The C-F...M(+) interaction was investigated by observation of the NMR spectroscopic changes and complexation studies between metal cations and the cage compounds 1 and 2 which have fluorobenzene units as donor atoms. As a result, the interaction was detected with all of the metal cations which form complexes with 1 and 2. The stability of the complexes of 1 and 2 was determined by the properties of the metal cations (ionic radii and degree of hydrolysis), not by the hard-soft nature of the cations. Crystallographic analyses of Tl(+) subset 1 and La(3+) subset 2 provided structural information (interatomic distances and bond angles), and the bond strengths, C-F...M(+), O...M(+), and N...M(+), were estimated by Brown's equation based on the structural data. Short C-F...Tl(+) (2.952-3.048 A) distances were observed in the complex Tl(+) subset 1. The C-F bond lengths in the complexes, Tl(+) subset 1 and La(3+) subset 2, are elongated compared to those of the metal-free compounds. Interestingly, no solvent molecules including water molecules were coordinated to La(3+) in the La(3+) subset 2. The stabilization energy of cation-dipole interaction was calculated on the basis of the data from X-ray crystallographic analysis, and it is roughly consistent with the (-)Delta H values estimated in solution. Thus, the C-F...M(+) interaction can be expressed by the cation-dipole interaction. This result explains the fact that compound 1 which has fluorine atom as hard donor strongly binds soft metals such as Ag(+) and Tl(+). Furthermore, it was concluded that the fluorobenzene unit has a poor electron-donating ability compared to that of ether oxygen or amine nitrogen, and thus the ratio of the coordination bond in C-F...M(+) is small. The specific and remarkable changes in the (1)H, (13)C, and (19)F NMR spectra were observed accompanied by the complexation between M(+) and the hosts 1 and 2. These spectral features are important tools for the investigation of the C-F...M(+) interaction. Furthermore, F.Tl(+) spin couplings were observed at room temperature in the Tl(+) subset 1, 2 (J(F-Tl) = 2914 Hz for Tl(+) subset 1 and 4558 Hz for Tl(+) subset 2), and these are clear and definitive evidence of the interaction.     

The thermodynamics of ethylene-diamine complexes of silver

The silver(I)-ethylenediamine system has been investigated and the existence of AgHL(2+) AgH(2)L(3+)(2), AgHL(2+)(2), AgL(+)(2) and Ag(2)L(2+)(2) with stability constants 10(2.33), 10(4.88), 10(6.47), 10(7.64) 10(13.13) has been demonstrated.     

Lower rim 1,3-di{4-antipyrine}amide conjugate of calix[4]arene: synthesis, characterization, and selective recognition of Hg2+ and its sensitivity toward pyrimidine bases

The structurally characterized lower rim 1,3-di{4-antipyrine}amide conjugate of calix[4]arene (L) exhibits high selectivity toward Hg(2+) among other biologically important metal ions, viz., Na(+), K(+), Ca(2+), Mg(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), Pb(2+), and Ag(+) as studied by fluorescence, absorption, and ESI MS. L acts as a sensor for Hg(2+) by switch-off fluorescence and exhibits a lowest detectable concentration of 1.87 ± 0.1 ppm. The complex formed between L and Hg(2+) is found to be 1:1 on the basis of absorption and fluorescence titrations and was confirmed by ESI MS. The coordination features of the mercury complex of L were derived on the basis of DFT computations and found that the Hg(2+) is bound through an N(2)O(2) extending from both the arms to result in a distorted octahedral geometry with two vacant sites. The nanostructural features such as shape and size obtained using AFM and TEM distinguishes L from its Hg(2+) complex and were different from those of the simple mercuric perchlorate. L is also suited to sense pyrimidine bases by fluorescence quenching with a minimum detection limit of 1.15 ± 0.1 ppm in the case of cytosine. The nature of interaction of pyrimidine bases with L has been further studied by DFT computational calculations and found to have interactions through a hydrogen bonding and NH-π interaction between the host and the guest.     

Studies on the polymer + plasticizer membrane-electrode-VIII Use of the PVC + tricresyl phosphate membrane as indicating electrode in potentiometric precipitation titration

Results obtained by use of the PVC + tricresyl phosphate membrane-electrode in potentiometric precipitation titration of some halides and pseudohalides are given. Solutions of Ag(+), Tl(+) and Hg(2)(2+) were used as titrants, to which the membrane is responsive. The fast response to Ag(+) ions allowed the determination of iodide by automatic recording of the potentiometric curve (or its derivative).     

Fluorescent zinc(II) complex exhibiting "on-off-on" switching toward Cu2+ and Ag+ ions

Binuclear zinc(II) and copper(II) complexes based on a new Schiff base ligand N,N'-bis(2-hydroxybenzilidene)-2,4,6-trimethylbenzene-1,3-diamine (H(2)L) have been synthesized. The ligand H(2)L and complexes under investigation have been characterized by elemental analyses, spectral (FT-IR, (1)H, (13)C NMR, ESI-MS, electronic absorption, emission), and electrochemical studies. The structures of H(2)L and complexes [{Zn(C(23)H(18)N(2)O(2))}(2)] (1) and [{Cu(C(23)H(18)N(2)O(2))}(2)]·H(2)O (2) have been determined crystallographically. Selective "On-Off-On" switching behavior of the fluorescent complex 1 has been studied. The fluorescence intensity of 1 quenches (turns-off) upon addition of Cu(2+), while enhances (turns-on) in the presence of Ag(+) ions. The mechanisms of "On-Off-On" signaling have been supported by (1)H NMR, ESI-MS, electronic absorption, and emission spectral studies. Job's plot analysis supported 1:1 and 1:2 stoichiometries for Cu(2+) and Ag(+) ions, respectively. Association and quenching constants have been estimated by the Benesi-Hildebrand method and Stern-Volmer plot. Moreover, 1 mimics a molecular keypad lock that follows correct chemical input order to give maximum output signal.     

Synthesis,spectroscopic characterization and catalytic activity of cis-dioxidomolybdenum (VI) complexes with chiral tetradentate Schiff bases

New chiral mononuclear cis-dioxidomolybdenum (VI) complexes, MoO ₂ L ¹ –MoO ₂ L ¹⁰ , with tetradentate Schiff bases derived from various substituted salicylaldehydes and 1S,2S-(+)-2-amino-1-(4-nitrophenyl)-1,3-propanediol were synthesized. All complexes were characterized by elemental analysis, circular dichroism, electronic and IR spectroscopy. ¹H NMR and also two-dimensional (COSY, NOESY and gHSQC) NMR measurements made for MoO ₂ L ¹ –MoO ₂ L ¹⁰ complexes show that Schiff bases are coordinated to the MoO₂²⁺ cation, creating facial (fac) and meridional (mer) types of geometrical isomers. Moreover, catalytic activity studies were also performed for all complexes in asymmetric sulfoxidation of thioanisole and epoxidation of styrene, cyclohexene and two monoterpenes, i.e. S(−)-limonene and (−)-α-pinene, using aqueous 30% H₂O₂ or tert-butyl hydroperoxide as the oxygen source.     

Synthesis, characterization, redox property and biological activity of Ru(II) carbonyl complexes containing O,N-donor ligands and heterocyclic bases

Stable ruthenium(II) carbonyl complexes having the general composition [RuCl(CO)(PPh3)(B)(L)] (where B=PPh3, pyridine, piperidine or morpholine; L=anion of bidentate Schiff bases (Vanmet, Vanampy, Vanchx)) were synthesized from the reaction of [RuHCl(CO)(PPh3)2(B)] with bidentate Schiff base ligands derived from condensation of o-vanillin with primary amines such as methylamine, 2-aminopyridine and cyclohexylamine. The new complexes were characterized by elemental analysis, IR, UV-Vis and 1H NMR spectral data. The redox property of the complexes were studied by cyclic voltammetric technique and the stability of the complexes towards oxidation were related to the electron releasing or electron withdrawing ability of the substituent in the phenyl ring of o-vanillin. An octahedral geometry has been assigned for all the complexes. In all the above reactions, the Schiff bases replace one molecule of PPh3 and hydride ion from the starting complexes, which indicate that the Ru-N bonds present in the complexes containing heterocyclic nitrogen bases are stronger than the Ru-P. The Schiff bases and their ruthenium(II) complexes have been tested in vitro to evaluate their activity against bacteria, viz., Staphylococcus aureus (209p) and E. coli (ESS 2231).     

Silver(I) complexes in coordination supramolecular system with bulky acridine-based ligands: syntheses, crystal structures, and theoretical investigations on C-H...Ag close interaction

In our efforts to investigate the coordination architectures of transition metals and organic ligands with tailored structures, we have prepared two structurally related rigid bulky acridine-based ligands, 9-[3-(2-pyridyl)pyrazol-1-yl]- acridine (L(1)) and 9-(1-imidazolyl)acridine (L2), and synthesized and characterized four of their Ag(I) complexes, {[AgL1](ClO4)}2 (1), {[AgL1](NO3)}2 (2), [AgL2(2)](ClO4) (3), and {[(Ag3L2(3))(NO3)](NO3)2(H2O)}(infinity) (4). The single-crystal X-ray diffraction analysis shows that the structures of 1 and 2 are similar to each other, with the two intramolecular Ag(I) centers of each complex being encircled by two L1 ligands; this forms a unique boxlike cyclic dimer, which is further linked to form one-dimensional (1D) chains of 1 and a two-dimensional (2D) network of 2 by intermolecular face-to-face pi...pi stacking and/or weak C-H...O hydrogen-bonding interactions, respectively. 3 has a mononuclear structure, which is further assembled into a 2D network via intermolecular Ag...O and pi...pi stacking weak interactions. 4 possesses two different 1D motifs that are further interlinked through interlayer face-to-face pi...pi stacking and Ag...O weak interactions, resulting in a 2D network. It is worth noting that one of the interesting structural features of 1, 2, and 4 is the presence of obvious C-H...M hydrogen-bonding interactions between the Ag centers and some acridine ring H atoms identified by X-ray diffraction on the basis of the van der Waals radii. Furthermore, as a representative example, full geometry optimization on the basis of the experimental structure, the natural bond orbital (NBO), and topological analysis of 1 were carried out by DFT and AIM (Atoms in Molecules) calculations. The total C-H...Ag interaction energy in 1 is estimated to be about 14 kJ/mol. Therefore, this work offers three new rare examples (1, 2, and 4) that exhibit C-H...Ag weak interactions, in which the N donors of the acridine rings coordinate to Ag(I) ions. Also, these results strongly support the existence of C-H...Ag close interactions and allow us to have a better understanding of the nature of such interactions in the coordination supramolecular systems.