Carboxy Oxygen Atoms Research Articles

Production of novel mung bean peptides-based zinc supplement: Process optimization, chelation mechanism, and stability assessment in vitro

To realize the add value of protein resources from mung bean processing by-products, mung bean peptides-zinc chelate (MBP-Zn), a novel zinc supplement, was synthesized in the present study. Under the optimized process conditions (MBP concentration of 6%, pH 5.0, mass ratio of MBP to zinc salt of 2:1, temperature of 60 °C and time of 80 min), the zinc chelation rate of MBP-Zn reached up to 98.15%. Integrating the results of Fourier transform infrared spectroscopy and amino acid profiles, it is inferred that zinc ions may bind to MBP via carboxy oxygen, amino nitrogen, and sulfhydryl sulfur atoms. The incorporation of zinc ions dramatically changed the structure of the chelate, as evidenced by the blue shift and attenuation of the original UV and fluorescence spectra. The morphological analysis revealed that Zn2+ induced cross-linking of peptides, forming enlarged nanoparticles that fragmented the original smooth surface of MBP. Surprisingly, the superior stability of MBP-Zn over the conventional zinc supplement ZnSO4 was confirmed, regardless of pH and temperature variations, or simulated gastrointestinal digestion circumstances. These findings pave the way for the large-scale production of mung bean peptide-based zinc supplements as nutraceuticals in the food industry.

A new CuII-dinuclear paddlewheel complex. Structural and electronic properties

A new paddlewheel dinuclear CuII complex [Cu2(HL)4(MeOH)2](MeOH)4, Cu2-PW was obtained using the 3,5-di‑tert‑butyl‑salicylic acid as a ligand (H2L). The Cu2-PW crystallizes in the monoclinic P2/c space group having a Cu…Cu distance of 2.5727(17) Å. The hydrogen bonds between coordinated and solvate methanol molecules link the structure into a pseudo-one-dimensional array with a Cu…Cu interdimer distance of 9.180(5) Å. Temperature dependence of magnetic susceptibilities revealed a strong antiferromagnetic interaction between the two CuII ions (J = −323 cm−1). DFT calculations showed that the strong antiferromagnetic behavior is originated from magnetic orbital centered only on CuII cations and carboxy oxygen atoms, with a calculated exchange magnetic coupling constant of J12= -311 cm−1. Time-dependent calculations were also performed to characterize the main electronic transition involved in the two well-defined maxima observed in solid-state. The results show that the maximum at 695 nm corresponds to d-d and carboxylate intraligand transitions, while the maximum centered at 320 nm was assigned to phenyl to carboxylate ILCT transition. The shoulder located around 400 nm corresponds to MLCT transition from HL− ligand to CuII center. In our knowledge, this is the first time that a copper paddlewheel complex with the salicylic ligand is studied using the hole-electron method to give a univocal assignment for the UV–vis spectrum.

The first 3, 5, 6-trichloropyridine-2-oxyacetate bridged manganese coordination polymer with features of π⋯π stacking and halogen⋯halogen interactions: Synthesis, crystal analysis and magnetic properties

A new coordination polymer [Mn(3, 5, 6-tcpa)2(2, 2′-bipy)]n (1) has been synthesized by the hydrothermal reaction of manganese sulfate hydrate with 3, 5, 6-trichloropyridine-2-oxyacetic acid (3, 5, 6-Htcpa) and 2, 2′-bipyridine (2, 2′-bipy) coligands. The X-ray single-crystal diffraction analysis shows that the MnII center is in deformed octahedral geometry bonded by two pyridyl nitrogen atoms of 2, 2′-bipy molecule and four carboxy oxygen atoms of four different 3, 5, 6-tcpa− ligands. The 3, 5, 6-tcpa− anions play as bidentate bridging-μ2 linkers and connect neighbouring MnII ions together to form the 1D double-stranded chain structure of 1, which displays interesting chair form [Mn2(COO)2] eight-membered rings. 1 is further assembled into 3D network by the co-effects of π⋯π stacking and Cl⋯Cl halogen bonds interactions. In addition, the magnetic characterizations indicated weak antiferromagnetic coupling between MnII centers for 1.

Two mononuclear zinc(II) complexes constructed by two types of phenoxyacetic acid ligands: syntheses, crystal structures and fluorescence properties

Abstract Two new mononuclear complexes, [Zn(3-Hcpa)2(H2O)4] (1) and [Zn(3,5,6-tcpa)2(H2O)4] [Zn(3,5,6-tcpa)2(H2O)2] (2) (3-H2cpa = 3-carboxy-phenoxyacetic acid, 3,5,6-Htcpa = 3,5,6-trichloro pyridine-2-oxyacetic acid), were synthesized and structurally characterized. The single-crystal X-ray diffraction analysis showed that in 1 the ZnII ion lies on an inversion center of an octahedron formed by four aqua ligands and two carboxy oxygen atoms of two unidentate 3-Hcpa− anions in trans-arrangement. Complex 2 is a co-crystal consisting of two discrete and stereochemically different complexes: one with an octahedrally, and the other a tetrahedrally coordinated zinc center. The six-coordination about the first ZnII ion comprises four oxygen atoms from water (H2O) molecules and two from the carboxy groups of monodentate trans-related 3,5,6-tcpa− ligands. The four-coordination about the second ZnII ion is comprised of two H2O ligands and two unidentate carboxy oxygen atoms from 3,5,6-tcpa− ligands. O–HLO hydrogen bond and/or ClLCl halogen bond interactions play an important part in construction of the three-dimensional (3D) networks for 1 and 2. The photoluminescence spectra reveal that both 1 and 2 display luminescent properties in the violet region.

Mixed ligand oxidovanadium(IV) complexes: Synthesis, spectral, structural characterization and catalytic degradations of methyl orange

Mixed ligand oxidovanadium(IV) complexes VO(ox)(im)3·H2O (1), VO(ox)(4-mim)3 (2), K2[VO(ox)2(2-mim)]·2H2O (3) and [V2O2(edta)(phen)2]·11H2O (4) (H2ox = oxalic acid, H4edta = ethylenediaminetetraacetic acid, im = imidazole, 2-mim = 2-methylimidazole, 4-mim = 4-methylimidazole, and phen = 1,10-phenanthroline) have been obtained at room temperature and under hydrothermal condition respectively. 1–3 feature bidentate oxalate with two carboxy oxygen atoms, and the dimeric complex 4 contains hexadentate edta as bridging ligand. 1–4 have been fully characterized by elemental, thermogravimetric and single crystal X-ray structural analyses, as well as IR, UV–vis and EPR spectroscopies. Moreover, 1, 2 and 4 were tested for the catalytic degradations of methyl orange (MO) with H2O2.

Solvation and protonation of coumarin 102 in aqueous media: a fluorescence spectroscopic and theoretical study.

The ground- and excited-state protonation of Coumarin 102 (C102), a fluorescent probe applied frequently in heterogeneous systems with an aqueous phase, has been studied in aqueous solutions by spectroscopic experiments and theoretical calculations. For the dissociation constant of the protonated form in the ground state, pKa = 1.61 was obtained from the absorption spectra; for the excited-state dissociation constant, pKa* = 2.19 was obtained from the fluorescence spectra. These values were closely reproduced by theoretical calculations via a thermodynamic cycle (the value of pKa* also by calculations via the Förster cycle) using an implicit–explicit solvation model (polarized continuum model + addition of a solvent molecule). The theoretical calculations indicated that (i) in the ground state, C102 occurs primarily as a hydrogen-bonded water complex, with the oxo group as the binding site, (ii) this hydrogen bond becomes stronger upon excitation, and (iii) in the ground state, the amino nitrogen atom is the protonation site, and in the excited state, the carboxy oxygen atom is the protonation site. A comprehensive analysis of fluorescence decay data yielded the values kpr = 3.27 × 10(10) M(–1) s(–1) for the rate constant of the excited-state protonation and kdpr = 2.78 × 10(8) s(–1) for the rate constant of the reverse process (kpr and kdpr were treated as independent parameters). This, considering the relatively long fluorescence lifetimes of neutral C102 (6.02 ns) and its protonated form (3.06 ns) in aqueous media, means that a quasi-equilibrium state of excited-state proton transfer is reached in strongly acidic solutions.

Phase transition originating from order-disorder transformations of carboxy oxygen atoms coupled with dynamic proton motions in [PhCH2 NH(CH3)2]2 C2O4⋅H2 C2O4.

A new molecular phase transition material, [PhCH(2) NH(CH(3))(2)](2) C(2)O(4)⋅H(2)C(2)O(4), which undergoes a reversible phase transition at 151.6 K, has been successfully synthesized. Differential scanning calorimetry (DSC), specific heat capacity, and dielectric measurements confirm its reversible phase transition with a large thermal hysteresis of 15.1 K, demonstrating that the phase transition is typical first order. Variable-temperature single-crystal X-ray diffraction analyses reveal that the order-disorder transformations of carboxy oxygen atoms induce the structural phase transition. A slight reorientation of the oxalic acid unit is discovered to accompany the ordering of carboxy oxygen atoms at low temperature. The DSC measurement result of the deuterated analog is different to that of 1, indicating that proton dynamic motions in hydrogen bonds also contribute to the phase transition.

Synthesis, structure, and antimicrobial activity of copper(II) chelates containing imidazole and condensation products of α-amino acids with salicylaldehyde and its derivatives

Salicylaldehyde, 5-bromo- and 5-nitrosalicylaldehydes, 2-hydroxynaphthalene-1-carbaldehyde, and 2,3-, 2,4-, and 2,5-dihydroxybenzaldehydes reacted with glycine, alanine, and phenylalanine in ethanol in the presence of imidazole (Im) and copper(II) acetate hydrate to give copper(II) chelates with the composition Cu(Im)(L) · nH2O (H2L is the condensation product of the above aldehydes with α-amino acids; n = 0–2). The structure of the complex Cu(Im)(L1) [H2L1 = 2-(2-hydroxybenzylideneamino)acetic acid] was determined by X-ray analysis. The crystalline structure of [2-(2-hydroxybenzylideneamino)acetato](imidazole)copper is formed by polymeric chains of the Cu(Im)(L1) molecules linked through bridging oxygen atoms in the carboxy groups of the Schiff base ligand. The coordination unit has a distorted tetragonal pyramid configuration, where the pyramid base is composed of the phenol and carboxy oxygen atoms, CH=N nitrogen atom in the ligand H2L1 and imidazole nitrogen atom. The oxygen atom in the carboxy group in the neighboring molecule occupies the apical position of the coordination pyramid. The other coordination compounds also have polynuclear structure with the Schiff base H2L acting as doubly deprotonated tridentate O,N,O-ligand and bridging carboxy groups. Thermal decomposition of the complexes includes their dehydration (70–95°C), while complete thermal decomposition occurs at 360–530°C. The synthesized complexes showed selective antimicrobial activity in the concentration range from 75 to 300 μg/ml against a number of standard strains of Staphylococcus aureus and Escherichia coli.

Solid-State Synthesis and Structural Characterization of Hydrated Zinc (II) Tartrate Complex

A new dinuclear hydrated zinc (II) tartrate complex has been successfully synthesized via a solid-state reaction at low temperature under the presence of polyethylene glycol 400 as a structure-directed agent and structurally characterized by single-crystal X-ray diffraction, and further identified by element analyses, FT-IR spectra and TG/DTA measurements. It formulates as [Zn4(C4H4O6)4(H2O)8]·(H2O)12 and crystallizes in monoclinic system, and the space group is P2 (1)/c with cell parameters a = 13.681(3), b = 17.059(3), c = 18.483(4) A, β = 96.62(3)°, and Z = 4. The structure of the title complex consists of two crystallographic independent dimeric units of [Zn2(C4H4O6)2(H2O)4], 12 lattice water molecules. In each dimeric unit, two tartrate dianions bridges the two Zn (II) ions by using one hydroxy oxygen and one carboxy oxygen atoms as donor atoms, respectively. Each Zinc atom is six-coordinated by four oxygen atoms from two tartrate dianions and two oxygen atoms from the water molecules. A new dinuclear hydrated zinc (II) tartrate complex has been successfully synthesized via a solid-state reaction at low temperature and structurally characterized by single crystal X-ray diffraction, element analysis, FT-IR and TG/DTA measurements. The figure shows the ORTEP diagram of the title complex.

Synthesis and spectroscopic characterization of metal complexes with naphthofuran-2-carbohydrazide Schiff 's base

Two Schiff-base ligands (I) naphthofuro-[phenylmethine]carbohydrazone [NPMC] and (II) naphthofruo-[3,4-dimethoxyphenylmethine]carbohydrazone [NDMeOPMC] were prepared by reaction between naphthofuran-2-carbohydrazone and benzaldehyde or 3,4-dihydroxybenzaldehyde, respectively. Both ligands are bidentate by coordinating through carboxy oxygen and azomethine nitrogen atoms. Complexes of the type MLX n were obtained. where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), UO2(II) and Th(IV), L = [NPMC] or [NDMeOPMC] and X = Cl2 for Co(II), Cu(II), Ni(II), Zn(II), Cd(II) and Hg(II) complexes, X = NO3, n = 2 for UO2(II) complexes and X = NO3, n = 4 for Th(IV) complexes. All the complexes and ligands were characterized IR, electronic, 1H NMR, ESR, conductance data and magnetic susceptibility measurements.

Crystal Structure and Characterization of the Dinuclear Cd(II) Complex [Cd(H2O)2(ο-HOC6H4COO)2

The structure of a new binuclear cadmium (II) complex, [Cd(H2O)2(Sal)2]2 (Sal= salicylate), has been determined by X-ray crystallography. It was also characterized by elemental analysis, its IR spectrum and thermogravimetric-differential scanning calorimetry (TG-DSC). It crystallizes in the monoclinic system, space group P2(1)/c, with lattice parameters a = 15.742(3) A, b = 12.451(3) A, c = 7.7225(15) A, beta = 96.07(3)degrees and Z = 4. Two cadmium (II) ions are bridged by two mu(2)-carboxy oxygen atoms. Each cadmium atom lies in a distorted capped octahedron coordination geometry. The thermal gravimetry (TG) data indicate that there are four discrete decomposition steps with two endothermic peaks and one exothermic peak. The final thermal decomposition product is CdO.

Synthesis and Structure of the Binuclear 1 : 1 Silver(I) 2-Hydroxy-3,5-dinitrobenzoate/Triphenylphosphine Complex

A room-temperature single-crystal X-ray structure determination of the 1 : 1 adduct of silver(I) 2-hydroxy-3,5-dinitrobenzoate/triphenyl-phosphine (AgL/PPh3) was recorded, showing it to be a binuclear centrosymmetric system with the silver atoms bridged by one of the carboxy oxygen atoms of each ligand, [(PPh3)Ag(μ-O)2Ag(PPh3)] as in the parent acetate; the phenolic oxygen, retaining its protonation, is hydrogen bonded within the ligand to the other feebly chelating carboxylate oxygen.

Synthesis, crystal structure and magnetic properties of a two-dimensional lamellar coordination polymer manganese(II) pyrazinecarboxylate

The two-dimensional (2D) lamellar coordination polymer [Mn(pzc)2]n (pzc = pyrazinecarboxylate) was prepared and its structure determined by X-ray diffraction. Each MnII ion lies in a distorted octahedron coordination sphere, and the pzc ligand adopts two types of bridging mode. As a result, there are two different distances between adjacent MnII atoms: one being 3.50(6) A viaμ2-O forming a dimer of MnII, and the other 5.65(4) A through the syn–anti carboxy oxygen atoms. The latter links the dimer to form an extended 2D lamellar structure. All MnII ions in each layer are nearly coplanar. The adjacent sheets are significantly associated via hydrogen bonding and the shortest interlayer Mn·Mn separation is 9.4 A. The e.s.r. spectrum shows a broad isotropic band centered at g = 2.019. Temperature-dependent magnetic susceptibility measurements (2.0–300 K) reveal the presence of an antiferromagnetic interaction in the coordination polymer.

Synthesis, crystal structure and e.p.r. spectra of one-dimensional manganese(II) 3,5-dinitrobenzoate dihydrate

The crystal structure of catena-diaquatetrakis(μ2-3,5-dinitrobenzoato-O,O′)manganese(II) has been determined by X-ray diffraction. It consists of a chain with the 3,5-dinitrobenzoate group acting in the syn-anti μ2-O,O′-bridging fashion, in which the MnII atom is octahedrally coordinated by two aqua ligands [2.162(3) A] and four carboxy oxygen atoms [Mn—O = 2.114(3) and 2.221(3) A]. The X-band e.p.r. spectra of this complex show a hyperfine structure due to MnII (I = 5/2) with a splitting factor (A) of 97 G at 5 K and 93 G at 19 K, respectively.

An Alternative Approach to Al2O2 Ring Systems by Unexpected Cleavage of Stable Al−F− and Si−O− Bonds

The reaction of dimethyl aluminum fluoride (Me2AlF, DMAF) with 2,6-diisopropylphenol and triethylcitrate, respectively, leads to the products (RO)6Al4F2Me4 (R = 2,6-i-Pr2C6H3) (1) and (ROAlFMe)2 (R = C(CH2COOEt)2(COOEt)) (2), containing Al2O2 ring systems. Both aluminum-μ-oxo fluorides have been structurally characterized. Fluorine exchange in the reaction of 2,6-diisopropylphenol with DMAF has been monitored using 19F NMR spectroscopy. The proposed processes in solution are confirmed by the solid-state structure of 1. Compound 1 contains four aluminum centers forming three four-membered ring systems. The two outer cycles consist of bridging −OR groups, whereas the aluminum atoms in the central cycle are connected via fluorine atoms. Two of the aluminum atoms are 4-fold coordinated, and two are 5-fold coordinated. Compound 1 contains a rare four-membered Al2F2 ring system. Compound 2 exhibits a dimeric structure, with oxygen rather than fluorine atoms bridging the aluminum atoms. A further carboxy oxygen atom binds coordinatively to one aluminum atom in 2. The aluminum atoms are 5-fold coordinated. In search of an alternative approach to synthesizing Al2O2 ring systems, it has been found that neither DMAF nor trimethyl aluminum (Me3Al, TMA) reacts with (Me3Si)2O, whereas the reaction of diisobutyl aluminum hydride (i-Bu2AlH, DIBAH) with (Me3Si)2O leads to (i-Bu2AlOSiMe3)2 (3). In compound 3 the aluminum centers in the four-membered Al2O2 ring system are only 4-fold coordinated. This is the first example of a structurally characterized aluminum product obtained from (Me3Si)2O under cleavage of the Si−O bond.

Synthesis, crystal structures and properties of copper(II) complexes of Schiff base derivatives containing imidazole and β-alanine groups

Four copper(II) complexes with Schiff base ligands N-[(5-methylimidazol-4-yl)methylene]-β-alanine (HL1) and N-[(1-methylimidazol-2-yl)methylene]-β-alanine (HL2) and their reduced forms N-[(5-methylimidazol-4-yl)methyl]-β-alanine (HL3) and N,N-bis[(5-methylimidazol-4-yl)methyl]-β-alanine (HL4) have been synthesized. The crystal structures of [CuL1(H2O)(ClO4)] 1, [CuL2(H2O)(ClO4)] 2, [CuL3(Py)(ClO4)] 3 and [Cu2(L4)2][ClO4]2·2H2O 4 have been determined. Complexes 1 and 2 are structurally very similar, the copper(II) atom being tridentately chelated by the Schiff base using one carboxy oxygen atom and two nitrogen atoms at the equatorial positions, with the fourth equatorial position being occupied by another carboxy oxygen atom from an adjacent Schiff base; one aqua ligand and one perchlorate oxygen atom ligate at the axial positions, resulting in an elongated octahedral geometry. Each carboxy group in 1 and 2 acts in the syn-anti mode and bridges two adjacent copper(II) atoms via two equatorial positions, resulting in one-dimensional helical (Cu–O–C–O–Cu)n chains. In 3 the copper(II) atom is ligated by two nitrogen atoms, one carboxy oxygen atom from an L3 ligand and another nitrogen atom from pyridine at the equatorial position; the axial positions are occupied by one perchlorato oxygen atom and one carboxy oxygen atom from another L3 ligand, tridentately chelating an adjacent copper(II) atom, resulting in an elongated octahedral geometry. Complex 4 contains a dimeric cation with two very similar square-pyramidally co-ordinated copper(II) atoms. Each L4 ligand chelates a copper(II) atom in a tetradentate mode with the three nitrogen atoms occupying the equatorial positions and the carboxy oxygen atom the apical position. The fourth equatorial position is taken by a carboxy oxygen atom from another L4 ligand chelating another copper(II) atom, resulting in a bis(carboxylato-O)-bridged dimeric structure. The electronic and EPR spectra and redox properties of 1–4 are also discussed.

Synthesis and structures of carboxylate-bridged polynuclear copper(II)–lanthanide(III) complexes [CuLn(C5H5N+CH2CO2−)5(H2O)5][ClO4]5·2H2O (Ln = La or Nd) and [Cu3Nd2(C5H5N+CH2CO2−)10(NO3)2(H2O)8][ClO4]10·4H2O

Two types of carboxylate-bridged copper(II)–lanthanide(III) complexes, [CuLn(C5H5N+CH2CO2–)5(H2O)5][ClO4]5· 2H2O 1 (LnIII = LaIII a or NdIII b) and [Cu3Nd2(C5H5N+CH2CO2–)10(NO3)2(H2O)8][ClO4]10·4H2O 2, have been synthesized and characterized by X-ray structural analysis. Complexes 1a and 1b are isomorphous. In both, a CuII atom is quadruply bridged to a LnIII atom by four µ-carboxylate groups at the basal positions, and co-ordinated by an aqua ligand at the apical position to form a square-pyramidal CuO4(OH2) geometry, while the LnIII atom is co-ordinated in a monocapped square antiprism by five carboxy oxygen atoms and four aqua ligands. In 2, a pair of CuII atoms in two centrosymmetrically related tetrakis(µ-carboxylate)-bridged dinuclear CuIINdIII subunits is each linked to the central CuII atom by a single syn-antiµ-carboxylate bridge, resulting in a pentanuclear cation. The central CuII atom is co-ordinated by two carboxy oxygen atoms and two aqua ligands in a distorted square-planar fashion; the other two CuII atoms adopt the same square-pyramidal geometry, each being ligated by the four oxygen atoms from the quadruple carboxylate bridges at the basal plane and by one oxygen atom of the syn-antiµ-carboxylate group at the apical position. The NdIII atom is co-ordinated in a distorted monocapped square antiprism by the four carboxy oxygen atoms, three aqua ligands and a chelate nitrate group.

Synthesis, crystal structure and cyclic voltammetry of square-pyramidal acetatoaqua{ (4-methylimidazol-5-yl)methylene histamine}copper(II) perchlorate

The copper atom in acetatoaqua[[(4-methylimidazol-5- yl)methylene]histamine]-copper(II) perchlorate (1) is N,N,N-chelated by the [(4-methylimidazol- 5-yl)methylene]histamine [Cu–N=1.969(3) ∼2.019(3) A] donor ligand. The aqua ligand occupies the apical site of the square-pyramidal coordination polyhedron [Cu–O= 2.365(3) A], whose fifth site is occupied by the carboxy oxygen atom of the monodentate acetato anion [Cu–O=1.960(3)A]. Cyclic voltammetry in MeCN and N,N-dimethylformamide (DMF) gives a voltage of −0.39 and −0.37 V versus s.c.e, which compares well with the value obtained for Cu,Zn superoxide dimuthase itself.

Preparation and crystal structures of two monomeric lanthanide(III) complexes containing betaine and nitrato ligands: [Ln(bet) 2(NO 3) 3(H 2O) 2] (LnLa and Sm)

Two monomeric lanthanide(III) complexes containing carboxylato and nitrato ligands, [Ln(bet) 2(NO 3) 3(H 2O) 2] (bet = trimethylammonioacetate, LnLa and Sm), have been prepared and characterized by X-ray crystallography. Although the complexes crystallized in different space groups, they adopt analogous structures, with the Ln atom being surrounded in a distorted square-antiprismatic environment by two monodentate carboxylato groups three chelate nitrato groups and two water molecules. The LnO bond lengths are in the ranges 2.489(2)–2.710(3) and 2.19(1)–2.86(2) Å for the La and Sm complexes, respectively. The uncoordinated carboxy oxygen atoms form intramolecular hydrogen bonds with the aqua ligands.

Molecular structure and hydrogen bonding of 4-dimethylaminopyridinioacetate in its crystalline dihydrate and hydrochloride trihydrate, L·2H2O and [L2H]Cl·3H2O (L=p-Me2NC5H4N+CH2CO2 −)

The crystalline dihydrate and hydrochloride trihydrate of a new betaine, namely, L·2H2O (1) and [L2H]Cl·3H2O(2) (L=p-Me2NC5H4N+CH2CO2), have been synthesized and characterized by X-ray crystallography. Molecule L in compound1 [space groupPbcn, witha=15.732(3),b=7.894(2),c=18.304(4) A, andZ=8] possesses approximateC s symmetry. The formation of hydrogen bonds by water molecules bridging neighboring carboxy oxygen atoms leads to an infinite two-dimensional network composed of a packing of two different kinds of 12-membered rings. In compound2 [space group PT witha=7.341(2),b=9.543(2),c=17.010(4) A, α=82.43(2)°, δ=80.34(2)°, λ=74.05(2)°, andZ=2], the carboxylate groups of a pair of betaine molecules are bridged by a proton to form a dimeric cation L2H+ with a very strong asymmetric hydrogen bond of length 2.464(7) A. The crystal structure features a hydrogen-bonded corrugated ribbon comprising an alternate arrangement of edge-sharing centrosymmetric (H2O)4(Cl−)2 and (H2O)4 rings running parallel to thea axis.