Simultaneous potentiometric determination of ClO(3)(-)-ClO(2)(-) and ClO(3)(-)-HClO by flow injection analysis using Fe(III)-Fe(II) potential buffer

A rapid potentiometric flow injection technique for the simultaneous determination of oxychlorine species such as ClO₃⁻–ClO₂⁻ and ClO₃⁻–HClO has been developed, using both a redox electrode detector and a Fe(III)–Fe(II) potential buffer solution containing chloride. The analytical method is based on the detection of a large transient potential change of the redox electrode due to chlorine generated via the reaction of the oxychlorine species with chloride in the potential buffer solution. The sensitivities to HClO and ClO₂⁻ obtained by the transient potential change were enhanced 700–800-fold over that using an equilibrium potential. The detection limit of the present method for HClO and ClO₂⁻ is as low as 5×10⁻⁸ M with use of a 5×10⁻⁴ M Fe(III)–1×10⁻³ M Fe(II) buffer containing 0.3 M KCl and 0.5 M H₂SO₄. On the other hand, sensitivity to ClO₃⁻ was low when a potential buffer solution containing 0.5 M H₂SO₄ was used, but could be increased largely by increasing the acidity of the potential buffer. The detection limit for ClO₃⁻ was 2×10⁻⁶ M with the use of a 5×10⁻⁴ M Fe(III)–1×10⁻³ M Fe(II) buffer containing 0.3 M KCl and 9 M H₂SO₄. By utilizing the difference in reactivity of oxychlorine species with chloride in the potential buffer, a simultaneous determination method for a mixed solution of ClO₃⁻–ClO₂⁻ or ClO₃⁻–HClO was designed to detect, in a timely manner, a transient potential change with the use of two streams of potential buffers which contain different concentrations of sulfuric acid. Analytical concentration ranges of oxychlorine species were 2×10⁻⁵–2×10⁻⁴ M for ClO₃⁻, and 1×10⁻⁶–1×10⁻⁵ M for HClO and ClO₂⁻. The reproducibility of the present method was in the range 1.5–2.3%. The reaction mechanism for the transient potential change used in the present method is also discussed, based on the results of batchwise experiments. The simultaneous determination method was applied to the determination of oxychlorine species in a tap water sample, and was found to provide an analytical result for HClO, which was in good agreement with that obtained by the o-tolidine method and to provide a good recovery for ClO₃⁻ added to the sample.     

Catalytic activity of manganese(III)-oxazoline complexes in urea hydrogen peroxide epoxidation of olefins: The effect of axial ligands

The catalytic activity of two manganese(III)-oxazoline complexes [Mn(phox)₂(CH₃OH)₂]ClO₄ and Mn(phox)₃ (Hphox = 2-(2′-hydroxylphenyl)oxazoline), was studied in the epoxidation of various olefins. All of epoxidation reactions were carried out in (1:1) mixture of methanol:dichloromethane at room temperature using urea hydrogen peroxide (UHP) as oxidant and imidazole as co-catalyst. The epoxide yields clearly demonstrate the influence of steric and electronic properties of olefins, the catalysts and nitrogenous bases as axial ligand. [Mn(phox)₂(CH₃OH)₂]ClO₄ catalyst with low steric properties has higher catalytic activity than Mn(phox)₃. The highest epoxide yield (95%) was achieved for indene at the presence of [Mn(phox)₂(CH₃OH)₂]ClO₄ within 5 min. The proximal and distal interactions of strong π-donor axial ligands such as imidazole with the active intermediate are efficiently increased activity of the catalytic system.     

Constructions of a set of novel hydrogen-bonded supramolecules from reactions of cobalt(II) salt with bis(3,5-dimethylpyrazolyl)methane and different carboxylic acids

Reactions of CoX₂·6H₂O (X = Cl⁻, ClO₄⁻) with bis(3,5-dimethylpyrazolyl)methane (dmpzm) and formic acid, acetic acid, benzoic acid, salicylic acid, maleic acid, or fumaric acid under the presence of KOH solution produced a new family of Co(II)/dmpzm complexes, [Co(dmpzm)₂L]X·nH₂O (1: L = O₂CH, X = Cl, n = 2; 2: L = OAc, X = Cl, n = 3; 3: L = benzoate, X = ClO₄, n = 1/3; 4: L = salicylate, X = ClO₄, n = 1/3) and [Co₂(dmpzm)₄L](ClO₄)₂·nSolv (5: L = maleate, n = 3, Solv = H₂O; 6: L = fumarate, n = 2, Solv = MeOH). These compounds were structurally characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Compounds 1–4 are mononuclear while 5–6 are binuclear. Each cobalt atom of 1–6 is hexacoordinate, with a distorted octahedral CoN₄O₂ coordination geometry incorporating two N,N′-bidentate dmpzm ligands and one O,O′-bidentate carboxylate ligand. There are rich intra- and intermolecular hydrogen bonds in the crystals of 1–6, thereby forming either 2D hydrogen-bonded networks (1 and 2) or 3D hydrogen-bonded networks (3–6). In addition, the thermal behaviors of 1–6 were also investigated.     

Vibrational spectra, structure and hydrogen bonding of 5-tert-butylpyrazole and its zinc complexes

New zinc complexes [L₂ZnX₂] with X=Cl (I), Br (II), I (III) and NO₃ (IV), [L₃Zn(OClO₃)]ClO₄ (V) and [L₄Zn](ClO₄)₂ (VI) with 5-tert-butylpyrazole as ligand L were synthesized and characterized by infrared-, Raman-, mass- and NMR-spectroscopy. The assignment of the vibrational frequencies for the complexes in the range of 4000–80 cm⁻¹ is proposed. Analysis of the IR spectra in the range of ν_NH frequencies shows that 5-tert-butylpyrazole forms cyclic associates in the solid using intermolecular NHN hydrogen bonds. This was proven by a crystal structure determination, which showed that L exists as tetramers in the solid state. In solution there is an equilibrium between tetramers and monomers and, probably, dimers or trimers. In the complexes, the NH-groups of L form intramolecular H-bonds with the X-group. The intramolecular H-bond in VI has interionic character and partially dissociates in solution at high dilution. Ligand vibrations that are sensitive to the coordination and the dependence of their frequencies on the anionic group X has been revealed.     

Lewis acid-catalyzed atom transfer radical cyclization of unsaturated β-keto amides

The Lewis acid-catalyzed atom transfer radical cyclization reactions of olefinic -bromo β-keto amides were investigated. It was found Lewis acid Yb(OTf)₃ or Mg(ClO₄)₂ not only promoted the cyclization reactions, but also resulted in excellent trans stereocontrol in the cyclization products. With the catalysis of Lewis acid Yb(OTf)₃ or Mg(ClO₄)₂ at −78°C in the presence of Et₃B/O₂, the cyclization reactions of C-olefinic β-keto amides provided cyclic ketones, while the cyclization reactions of N-olefinic β-keto amides led to the formation of γ-lactams, which could be converted to 3-aza-bicyclo[3,1,0]hexan-2-ones.     

Viscometric and light scattering studies on azrechtic acid

Results are reported for viscometric and light scattering studies on azrechtic acid (ARA) in pure aqueous medium, in 0–02 N KCl and in a mixture of 0–02 N KCl, CaCl₂, MgCl₂. The investigations reveal the polyelectrolyte character of the azrechtic acid molecule. The corrected average value of the molecular weight from light scattering measurements is 1–7 × 10⁶. Assuming the polydisperse random coil as a suitable model for ARA molecules, the root-mean-square end-to-end distances have been calculated as 2570 Å in water, 1410 Å in 0–02 N KCl and 1180 Å in a mixture of 0–02 N KCl, CaCl₂, MgCl₂. The contraction of the molecules in the presence of neutral salts has been attributed to partial reduction of electrostatic repulsion due to similarly charged ions.     

Flow-injection chemiluminescence determination of chlortetracycline using on-line electrogenerated [Cu(HIO(6))(2)](5-) as the oxidant

A novel chemiluminescence (CL) flow system for the determination of chlortetracycline is described. It is based on the direct CL reaction of chlortetracycline and [Cu(HIO₆)₂]⁵⁻ in KOH medium. The unstable [Cu(HIO₆)₂]⁵⁻ was on-line electrogenerated by constant-current electrolysis. The CL intensity was linear with chlortetracycline concentration in the range of 0.1–100 μg ml⁻¹. The determination limit was 5.3×10⁻⁸ g ml⁻¹. The whole process could be completed in 1 min. The proposed method is suitable for automatic and continuous analysis, and has been applied satisfactorily to analysis of chlortetracycline in biological fluid.     

Electrochemical, HPLC and electrospray ionization mass spectroscopic analyses of peroxycitric acid coexisting with citric acid and hydrogen peroxide in aqueous solution

We successfully determined the molecular structure of peroxycitric acid (PCA) coexisting in the aqueous equilibrium mixture with citric acid (CA; 1,2,3-tricarboxylic-2-hydroxy propane) and hydrogen peroxide (H₂O₂) by a combined use of reversed-phase HPLC (RP-HPLC), potentiometric, hydrodynamic chronocoulometric (HCC) and electrospray ionization mass spectroscopic (ESI-MS) methods. Firstly, the RP-HPLC was employed to separate CA, PCA and H₂O₂ coexisting in the equilibrium mixture and the concentration of CA consumed (ΔC_CA) in the formation of PCA that was evidenced to be fairly stable during the RP-HPLC measurement was quantitatively measured based on the standard calibration curve of CA. Secondly, the total oxidant concentration (C_Ox) corresponding to peroxycarboxylic (–COOOH) group in PCA in the equilibrium mixture was determined using potentiometric measurement. The ratio of C_Ox/ΔC_CA was found to be 1.07, which indicates that only one –COOH group in CA molecule is oxidized to the corresponding –COOOH group in PCA molecule. Thirdly, using the HCC technique the diffusion coefficient of PCA, which could be electroreduced at a more positive potential by 1.0 V than the coexisting H₂O₂, was independently measured as 0.3 × 10⁻⁵ cm² s⁻¹ and at the same time, by considering ΔC_CA as the concentration of PCA, the number of electrons (n) required for the reduction of PCA was determined to be 2. The result obtained from RP-HPLC and HCC, i.e., n = 2 which is equivalent to one –COOOH group in PCA, is in agreement with that obtained from the combination of RP-HPLC and potentiometric measurements. Finally, the structure of PCA was proposed to contain one –COOOH group with a molecular mass of 208 confirmed by negative ion ESI-MS method. A probable molecular structure of PCA was discussed.     

2-(Phenyltelluromethyl)tetrahydrofuran (L) and 2-(2-{4-methoxyphenyl}telluroethyl)-1,3- dioxolane (L) and their palladium(II) and platinum(II) complexes

The nucleophile [ArTe⁻] generated in situ borohydride solution of Ar₂Te₂, reacts with 2-(chloromethyl) tetrahydrofuran and 2-(2-bromoethyl)-1,3-dioxolane resulting in L¹ and L², respectively. The complexes of palladium(II) and platinum(II) with L¹/L² having stoichiometries [MCl₂·L₂], [ML₂](ClO₄)₂, [(DPPE)ML₂](ClO)₄)₂, [(PPh₃)₂ML₂](ClO₄)₂ and [(phen)ML₂](ClO₄)₂ (where L = L¹/L² DPPE = Ph₂PC H₂CH₂PPh₂, PHEN = 1,10-phenanthroline and M = Pd/Pt) have been synthesized. IR, ¹H, ¹²⁵Te{¹H} and ³¹P{¹H} NMR and UV-vis spectral data of these species in conjunction with their molar conductance and molecular weight data have been used to authenticate the new species. In all complexes (1–20) the ligands L¹ and L² are coordinated through tellurium and in the complexes of formula [ML₂](ClO₄)₂ (M = Pd, Pt) the ligand is bidentate with the oxygen atom used in complexation. In solution, complexes PtCl₂L₂ exist as a mixture of cis and trans isomers whereas only the trans isomer was observed for the palladium analogues. The [(phen)PdL₂](ClO₄)₂(Q) quenches ¹O₂ readily. The plot of log [Q] vs time is linear. Mechanism compatible with the experimental observations is proposed.     

Dinuclear transition metal compounds of a decadentate pyrazole-containing chelating ligand. X-ray crystal structure of Co2(tthd)(ClO4)4(H2O)2(MeOH)1.75

A potentially decadentate ligand, 1,1,4,7,10,10-hexakis(3,5-dimethyl-1-pyrazolylmethyl)-1,4,7,10-tetraazadecane (tthd), has been synthesized from the reaction of tri-ethylenetetramine with six equivalents of N-hydroxymethyl-3,5-dimethylpyrazole. The tthd ligand forms coordination compounds, M₂(tthd)(ClO₄)₄(H₂O)_x, when M is Co, Ni, Cu, Zn and Cd and x = 4–8; and M₂(tthd)(A)₂(ClO₄)₂(H₂O)_x when M is Co and Ni, A is NCS or Cl, and x = 4–8. The cobalt compound, Co₂(tthd)(ClO₄)₂(H₂O)₂(MeOH)_1.75, crystallizes in the triclinic space group P1, a = 1.959(2), b = 1.5657(3), c = 2.1244(3) nm, = 105.5(1), β = 96.9(1), γ = 112.1(1). Due to severe disorder of the anions the structure could only be refined to an R_w, value of 0.099. The ligand acts as a decadentate, dinucleating ligand. The cobalt ions are distorted octahedrally surrounded by five N-atoms of the tthd ligand and an O-atom of water occupying the sixth coordination place. The other perchlorate compounds have very similar structures, as can be concluded from spectroscopic data.

In the thiocyanate and chloride compounds the anions have replaced the coordinated water molecules, resulting in octahedral Ni compounds. With Co thiocyanate, however, tthd acts as an octadentate ligand, resulting only in five-coordinated compounds.     

Self-assembly in dinuclear, cyclic homotetranuclear and cyclic heterotetranuclear complexes with a picolylhydrazone ligand

Reactions among Cu(ClO₄)₂ · 6H₂O, Cu(acac)₂/VO(acac)₂ and 3-methoxysalicylaldehyde Picoloylhydrazone in different solvents give three complexes, [Cu₂L(acac)(H₂O)₂]ClO₄ (1), [Cu₄L₂(acac)₂(py)₂](ClO₄)₂ (2) and (VO₂)₂L₂Cu₂(acac)₂ (3) (acac = acetyl acetonate and py = pyridine). There is an extended 2D structure in complex 1 constructed by hydrogen bonds between the binuclear complex cation and the ClO₄⁻ anion, and an extended 1D structure in complex 2 constructed by weak ππ stacking interactions between neighboring cyclic tetranuclear complex molecules. Complex 3 is the first oxovanadium–copper complex with a bridging oxo oxygen atom between the V atom and the Cu atom. The solid-state photoluminescent properties of the three title complexes have been studied. There is an antiferromagnetic interaction in 1.     

Supramolecular formation by aromatic ring stacking and hydrogen bonding in lanthanide(III) complexes with amino acids and 1,10-phenanthroline

[Eu(ABA)(phen)₂(H₂O)₃](ClO₄)₃·3phen·4.5H₂O (1) and [Eu(Val)(phen)₂(H₂O)₃](ClO₄)₃·3phen·2H₂O (2) are two new europium complexes with amino acids and 1,10-phenanthroline (phen=1,10-phenanthroline, ABA=-amino butyl acid, Val= -valine). Their crystal structures were measured by X-ray crystallography. Europium atoms in both complexes are nine-coordinated with bidentate 1,10-phenanthroline and carboxylate anion of amino acids, and water molecules. In the solid state, 1 and 2 have a structure involving aromatic stacking of the coordinated and non-coordinated 1,10-phenanthroline and the oxygen atoms of non-coordinated perchlorate anions being H-bond acceptors connect [Eu(ABA)(phen)₂(H₂O)₃]³⁺·3phen·4.5H₂O or [Eu(Val)(phen)₂(H₂O)₃]³⁺·3phen·2H₂O in their structures. In their interactions, several C–HO bonds play an important role. Owing to their different amino acid ligands and the number of lattice water molecules, there is some difference in their hydrogen bond patterns in 1 and 2. The side chain of -valine is involved in the formation of C–HO bonds. Hydrogen bond and π–π interactions determine the supramolecular formation of three-dimensional net works of both complexes.     

Synthesis and magnetism of the first tetranuclear copper(II)–iron(III) complexes of macrocyclic oxamides

Four novel tetranuclear macrocyclic complexes of the formula [(CuLⁱ)₃Fe](ClO₄)₃·3H₂O (i=1–4, Lⁱ are the dianions of the [14]N₄ and [15]N₄ macrocyclic oxamides, namely 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene, 2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene and 2,3-dioxo-5,6:14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclotetradeca-7,12-diene] have been prepared and characterized. These complexes are the first examples of oxamido-bridged Cu(II)–Fe(III) heterometallic species. Cryomagnetic studies on [(CuL¹)₃Fe](ClO₄)₃·3H₂O (1) and [(CuL³)₃Fe](ClO₄)₃·3H₂O (3) (77–300 K) revealed that the Cu(II) and Fe(III) ions interact antiferromagnetically through the oxamido bridge, with the exchange integral J=−30.8 cm⁻¹ for 1 and J=−28.7 cm⁻¹ for 3 based on . The interaction parameters have been compared with that of the related [Cu₃Mn] compound.     

Neutral pyridylmethylamide ligands and their mononuclear copper(II) complexes

Mononuclear copper(II) complexes of a family of pyridylmethylamide ligands HL, HL^Me, HL^Ph, HL^Me3 and HL^Ph3, [HL = N-(2-pyridylmethyl)acetamide; HL^Me = N-(2-pyridylmethyl)propionamide; HL^Ph = 2-phenyl-N-(2-pyridylmethyl)acetamide; HL^Me3 = 2,2-dimethyl-N-(2-pyridylmethyl)propionamide; HL^Ph3 = 2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide], were synthesized and characterized. The reaction of copper(II) salts with the pyridylmethylamide ligands yields complexes [Cu(HL)₂(OTf)₂] (1), [Cu(HL^Me)₂](ClO₄)₂ (2), [Cu(HL)₂Cl]₂[CuCl₄] (3), [Cu(HL^Me3)₂(THF)](OTf)₂ (4), [Cu(HL^Me3)₂(H₂O)](ClO₄)₂ (5a and 5b), [Cu(HL^Ph3)₂(H₂O)](ClO₄)₂ (6), [Cu(HL)(2,2′-bipy)(H₂O)](ClO₄)₂ (7), and [Cu(HL^Ph)(2,2′-bipy)(H₂O)](ClO₄)₂ (8). All complexes were fully characterized, and the X-ray structures vary from four-coordinate square-planar, to five-coordinate square-pyramidal or trigonal-bipyramidal. The neutral ligands coordinate via the pyridyl N atom and carbonyl O atom in a bidentate fashion. The spectroscopic properties are typical of mononuclear copper(II) species with similar ligand sets, and are consistent their X-ray structures.     

Development of an analytical method for beryllium in airborne dust by micellar electrokinetic chromatography

The separation of diacetylacetonato–beryllium [Be(acac)₂] from acetylacetone was achieved with micellar electrokinetic chromatography (MEKC) followed by subsequent beryllium analysis carried out using capillary electrophoresis. Analysis using a separation and absorption detector, with a 50 μm capillary cell, could detect approximately 1000 ppb of beryllium in the final sample. Be(acac)₂ is a promising reagent for absorption spectrophotometry, because its molar absorption coefficient, (32 000 l mol⁻¹ cm⁻¹) is very large. As the complex and acetylacetone have a similar absorption wavelength, the excess free ligand must removed from the sample to be measured. Acetylacetone is a weak acid with keto–enol tautomerism in aqueous solution. Acetylacetone and neutral Be(acac)₂ should be separated with capillary zone electrophoresis (CZE) using a neutral or basic buffer solution as the mobile phase. Although the pH and temperature of the mobile phase were optimized, separation with CZE was interfered with by a portion of acetylacetone. This interfering portion seems to be a neutral keto-form with the same migration time as Be(acac)₂. As a neutral species separation method, MEKC with sodium dodecyl sulfate was tried and the separation was completed. The optimum pH value and buffer temperature are pH 7.8 and 15°C, respectively.     

Aromatic guest inclusion by a tripodal ligand: Fluorescence and structural studies

The newly synthesized simple tripodal ligand tris-[2-(naphthalen-2-yloxy)-ethyl]-amine (L₁) act as a fluorescence signaling system for aromatic guest. It forms inclusion complexes with several electron deficient aromatic compounds. This inclusion phenomenon has been studied by steady-state fluorescence spectroscopy and solid-state structural analysis. Electron-rich L₁ shows dramatic color change and a concomitant quenching of luminescence in solution as well as solid phase when titrated with several other electron deficient aromatic guest molecules. Rather high selectivity towards the picric acid was observed. L₁ simultaneously forms inclusion complex and organic salt co-crystal with the composition [(L₁H⁺) (Pic⁻)]  PicH (PicH = picric acid) when crystallized in the presence of picric acid. In the solid state, it forms a strong π–π, C–Hπ and C–HO type interactions.     

Low-temperature heat capacity and thermodynamic properties of crystalline [Re2(Ala)4(H2O)8](ClO4)6 (Re = Eu, Er; Ala = alanine)

[Re₂(Ala)₄(H₂O)₈](ClO₄)₆ (Re=Eu, Er; Ala=alanine) were synthesized, and the low-temperature heat capacities of the two complexes were measured with a high-precision adiabatic calorimeter over the temperature range from 80 to 370 K. For [Eu₂(Ala)₄(H₂O)₈](ClO₄)₆, two solid–solid phase transitions were found, one in the temperature range from 234.403 to 249.960 K, with peak temperature 243.050 K, the other in the range from 249.960 to 278.881 K, with peak temperature 270.155 K. For [Er₂(Ala)₄(H₂O)₈](ClO₄)₆, one solid–solid phase transition was observed in the range from 270.696 to 282.156 K, with peak temperature 278.970 K. The molar enthalpy increments, ΔH_m, and entropy increments,ΔS_m, of these phase transitions, were determined to be 455.6 J mol⁻¹, 1.87 J K⁻¹ mol⁻¹ at 243.050 K; 2277 J mol⁻¹, 8.43 J K⁻¹ mol⁻¹ at 270.155 K for [Eu₂(Ala)₄(H₂O)₈](ClO₄)₆; and 4442 J mol⁻¹, 15.92 J K⁻¹ mol⁻¹ at 278.970 K for [Er₂(Ala)₄(H₂O)₈](ClO₄)₆. Thermal decompositions of the two complexes were investigated by use of the thermogravimetric (TG) analysis. A possible mechanism for the thermal decomposition is suggested.     

SO3(2-)-based chemiluminescence in unbuffered solution with ClO2 as oxidant and its analytical application

In this paper, SO3(2-)-chemiluminescence (CL) system in unbuffered solution with ClO2 as oxidant is proposed. ClO2 could oxidize sulfite in unbuffered solution to produce CL emission, and riboflavin could sensitize the ClO2-SO3(2-)-based CL system. The ClO2-SO3(2-)-riboflavin CL reaction was chosen as a model system and explored the possibility of SO3(2-)-based CL system in unbuffered solution. Compared with the reported SO3(2-)-based CL system in strong acid media, the proposed CL system owns its advantages. Combined with flow-injection analysis, the proposed CL system was applied to measurement of riboflavin in pharmaceuticals.     

Chemiluminescence flow-through sensor for pipemidic acid using solid sodium bismuthate as an oxidant

A novel chemiluminscence (CL) flow-through sensor for pipemidic acid is described. It was based on the sensitizing effect of pipemidic acid on the CL oxidation of sulfite by sodium bismuthate in H₂SO₄ media. The solid-phase sodium bismuthate was mechanicially immobilized on the sponge rubber inside of the CL flow cell as CL oxidant. The calibration graph is linear in the range 0.1-10 μg/ml with a detection limit of 6.2×10⁻⁸ g/ml (3σ). A complete analysis could be performed in 1 min with a relative standard deviation (R.S.D.) of 2.5% for 2 μg/ml pipemidic acid (n=8). This method has been successfully applied to determine pipemidic acid in pharmaceutical preparation.     

Controlled growth of calcium oxalate crystal in bicontinuous microemulsions containing amino acids

The growth of calcium oxalate (CaC₂O₄) crystal in water channels of three kinds of bicontinuous microemulsions, consisted of P-octyl polyethylene glycol phenylether (OP)/n-amyl alcohol/cyclohexane/water and above microemulsions containing tryptophan (Trp) or aspartic acid (Asp) has been studied. The products were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The results indicated that both surfactant and amino acids all could prompt the growth of calcium oxalate monohydrate (COM) crystal, but the crystal morphology varied with the different microemulsions, pH values of the aqueous solution in channels and concentrations of the reactants. Various crystal morphologies such as butterfly-like, hollow and spiny spherical could be observed easily. A model of molecular identification – organized assembly – pervasion-combination balance was proposed to explain the formation mechanism of CaC₂O₄ crystals in the microemulsions containing Asp.