Efficient syntheses of bis(m-phenylene)-26-crown-8-based cryptand/paraquat derivative [2]rotaxanes by immediate solvent evaporation method

A novel bis(m-phenylene)-26-crown-8-based cryptand has been synthesized. It has been used to prepare two 1:1 complexes with two paraquat derivatives with high association constants (6.5×10⁵ and 4.0×10⁵ M⁻¹) in acetone. In the solid state the cryptand forms a 2:1 threaded structure with paraquat and an interesting supramolecular poly[2]pseudorotaxane threaded structure with a dihydroxyethyl-substituted paraquat derivative, respectively. It has been further used to prepare cryptand/paraquat derivative [2]rotaxanes efficiently by the immediate solvent evaporation method using easily available 3,5-dimethylphenyl groups as the stoppers.     

Bis(m-phenylene)-32-crown-10/monopyridinium [2]pseudorotaxanes

The first crown ether/monopyridinium threaded structures, which are [2]pseudorotaxanes based on a new bis(m-phenylene)-32-crown-10/monopyridinium recognition motif, were successfully prepared as confirmed by proton NMR spectroscopy, electrospray ionization mass spectrometry, and X-ray analysis.     

1,2-Bis[N-(N′-alkylimidazolium)]ethane salts as new guests for crown ethers and cryptands

1,2-Bis[N-(N′-alkylimidazolium)ethane salts form complexes presumed to be pseudorotaxanes with crown ether and cryptand hosts. The association constants of 1,2-bis[N-(N′-butylimidazolium)]ethane bis(hexafluorophosphate) with dibenzo-24-crown-8 and a dibenzo-24-crown-8-based pyridyl cryptand were estimated as 24 (±1) and 348 (±30) M⁻¹, respectively, in acetonitrile at 25 °C. The pseudorotaxane-like structure of the 1:2 complex of the N′-methyl analog with the cryptand was observed by X-ray crystallography. Replacement of the ethylene spacer with propylene and butylene spacers resulted in K_a values an order of magnitude smaller.     

Inclusion [2]complexes based on the cryptand/diquat recognition motif

Seven diquat-based inclusion [2]complexes were studied by proton NMR spectroscopy, electrospray ionization mass spectrometry, and X-ray analysis. The hosts used in these inclusion [2]complexes are bis(5-hydroxymethyl-1,3-phenylene)-32-crown-10, a bis(m-phenylene)-26-crown-8-based cryptand, and five bis(m-phenylene)-32-crown-10-based cryptands. Bis(m-phenylene)-32-crown-10-based cryptands have been proved to be able to complex diquat much more strongly than bis(m-phenylene)-32-crown-10 itself and one containing a pyridyl moiety has one of the highest K_a values reported to date. These hosts form 1:1 complexes with diquat in solution and in the solid state. It was found that the improved binding from bis(m-phenylene)-32-crown-10 to bis(5-hydroxymethyl-1,3-phenylene)-32-crown-10 was due to a supramolecular cryptand structure formed by chelation of the two terminal OH moieties of bis(5-hydroxymethyl-1,3-phenylene)-32-crown-10 with a water molecule as a hydrogen-bonding bridge.     

Host size effect in the complexation of two bis(m-phenylene)-32-crown-10-based cryptands with a diazapyrenium salt

N,N′-Dimethyl-2,7-diazapyrenium bis(hexafluorophosphate) binds a C₃-symmetric bis(m-phenylene)-32-crown-10-based cryptand more strongly than N,N′-dimethyl-4,4′-bipyridinium bis(hexafluorophosphate) partly because of its better fit in size with the cryptand host cavity, while it binds a relatively smaller pyridyl cryptand less strongly due to its worse fit in size with the cryptand host cavity and the lack of hydrogen bonding to the pyridyl nitrogen atom of the host.     

Two bis(p-phenylene)-34-crown-10-based cryptand constitutional isomers: different binding abilities induced by structural alterations

Two novel bis(p-phenylene)-34-crown-10-based cryptand constitutional isomers were prepared and their host–guest complexations with paraquat were studied by ESI-MS, UV–vis spectroscopy, ¹H NMR spectra, and X-ray crystal structures. Notably, though the only difference between the two hosts is the location of the nitrogen atom on the third arms, they exhibited quite different binding abilities with paraquat. Competitive complexation was carried out and it may provide a simple way to construct sophisticated supramolecular materials with reversibility and adaptability.     

Quantitative study of stereospecific binding of monoclonal antibody to anti-benzo(a)pyrene diol epoxide-N-dG adducts by capillary electrophoresis immunoassay

The stereospecific binding of monoclonal antibody (mAb) 8E11 to anti-benzo(a)pyrene diol epoxide (BPDE)-dG adducts in single nucleoside, long oligonucleotide, and genomic DNA were quantitatively evaluated using noncompetitive and competitive capillary electrophoresis (CE) immunoassays. Two single-stranded TMR-BPDE-90mers containing a single anti-BPDE-dG adduct with defined stereochemistry and a fluorescent label at 5′-end were used as fluorescent probes for competitive CE immunoassay. To quantitatively evaluate the binding affinity through competitive CE immunoassays, a series of equations were derived according to the binding stoichiometry. The binding of mAb 8E11 to trans-(+)-anti-BPDE-dG displays strongest affinity (K_b: 3.57 × 10⁸ M⁻¹) among all four investigated anti-BPDE-dG mononucleoside adducts, and the cis-(−)-anti-BPDE-dG displays lowest affinity (K_b: 1.14 ×10⁷ M⁻¹). The binding of monoclonal antibody (mAb) 8E11 to BPDE-dG adducts in long DNA (90mer) preferentially forms the complex with a stoichiometry of 1:1, and that mAb 8E11 displays a slightly higher affinity with trans-(+)-anti-BPDE-90mers (K_b: 6.36 ± 0.54 × 10⁸ M⁻¹) than trans-(−)-anti-BPDE-90mers (K_b: 4.52 ± 0.52 × 10⁸ M⁻¹). The mAb 8E11 also displays high affinity with BPDE-dG adducts in genomic DNA (K_b: 3.74 × 10⁸ M⁻¹), indicating its promising applications for sensitive immuno-detection of BPDE-DNA adducts in genomic DNA.     

Thermodynamics of complexation of aqueous 18-crown-6 with potassium ion: apparent molar volumes and apparent molar heat capacities of aqueous 18-crown-6 and of the (18-crown-6 + potassium chloride) complex at temperatures (278.15 to 393.15) K, at molalities (0.02 to 0.3) mol · kg, and at the pressure 0.35 MPa

We have measured the densities at temperatures T = (278.15 to 363.15) K and heat capacities at T = (278.15 to 393.15) K of aqueous solutions of 18-crown-6 and of (18-crown-6 + KCl) at molalities m = (0.02 to 0.3) mol · kg⁻¹ and at the pressure 0.35 MPa. We have calculated apparent molar volumes V_? and apparent molar heat capacities C_p,? for 18-crown-6(aq), and we have applied Young’s Rule and have accounted for chemical speciation and relaxation effects to resolve V_? and C_p,? for the (18-crown-6: K⁺,Cl⁻)(aq) complex in the mixture. We have also calculated estimates of the change in volume Δ_rV_m, the change in heat capacity Δ_rC_p,m, the change in enthalpy Δ_rH_m, and the equilibrium quotient log Q for formation of the complex at T = (278.15 to 393.15) K and m = (0 to 0.3) mol · kg⁻¹.     

Determining the stoichiometry and binding constants of inclusion complexes formed between aromatic compounds and β-cyclodextrin by solid-phase microextraction coupled to high-performance liquid chromatography

The complexation of native β-cyclodextrin (CD) and seven aromatic compounds, namely, phenetole, toluene, m-xylene, naphthalene, biphenyl, fluorene and phenanthrene, has been studied for first time utilizing a solid-phase microextraction (SPME)–high-performance liquid chromatography (HPLC) method. The stoichiometries of the analyte:β-CD complexes were found to be either 1:1 or 1:2. The formation of 1:2 complexes was confirmed for naphthalene, biphenyl, fluorene, and phenanthrene only when utilizing relatively high concentrations of β-CD (up to 6.6 mM). The 1:2 stoichiometries were confirmed using the classical modified Benesi–Hildebrand (BH) method. The calculated binding constants for 1:1 stoichiometries (K₁) using the SPME method varied from 115.3 M⁻¹ for toluene to 3510 M⁻¹ for phenanthrene, whereas the corresponding values to the 1:2 stoichiometries (K₃) varied from 7.30 × 10⁵ M⁻² for biphenyl to 9.03 × 10⁶ M⁻² for naphthalene.     

Synthesis and analytical application of a novel tetradentate N(2)O(2) Schiff base as a chromogenic reagent for determination of nickel in some natural food samples

A novel sensitive chromogenic reagent, N,N′-bis(3-methylsalicylidene)-ortho-phenylene diamine (MSOPD), has been synthesized and used in the spectrophotometric determination of nickel. At pH 8, MSOPD can react with nickel ion at room temperature to form a 1:1 complex. The apparent molar absorptivity is 9.5 × 10⁴ l mol⁻¹ cm⁻¹ at 430 nm. Beer's low is obeyed over the range 0-1.0 × 10⁻⁵ M of nickel with a detection limit of 1.36 × 10⁻⁸ M. The relative standard deviation for measurement of 3.41 × 10⁻⁶ M nickel is 1.3% (n = 10). The method has successfully been applied to determination of trace amounts of nickel in some natural food samples.     

Characterization of steroidal saponins in crude extract from Dioscorea nipponica Makino by liquid chromatography tandem multi-stage mass spectrometry

The liquid chromatography-electrospray ionization-tandem multi-stage mass spectrometry (LC-ESI-MSⁿ) method was developed for the analyses and characterization of steroidal saponins in plant extract from the rhizome of Dioscorea nipponica Makino. The HPLC experiments were performed by means of a reversed-phase C₁₈ column and a binary mobile phase system consisting of water and acetonitrile under gradient elution conditions. Pseudoprotodioscin, methyl protodioscin and dioscin were identified by comparing the retention times, UV spectra and the fragmentation properties of [M − H]⁻ ions with the authentic standards. Four groups of steroidal saponin isomers possessed the [M − H]⁻ ions at m/z 1063, 1045, 901 and 1047, respectively, were observed during the LC-ESI(−)-MS analysis, and three groups of them except the pair of isomers with the [M − H]⁻ ions at m/z 1047 could be differentiated by LC-ESI(−)-MS³. Furthermore, the ESI-MSⁿ fragmentation behaviors of the [M + Li]⁺ ions of pseudoprotodioscin and methyl protodioscin have been investigated, and the observed information helped the structural elucidation of the more abundant isomer with the [M − H]⁻ ion at m/z 1047. As the result, a special sugar sequence of the saccharide chains was observed that not glucose but rhamnose might be connected with the hydroxyl group at C-3 position of the steroidal aglycone.     

(Mesitylene)ruthenium π-complexes with benzo-15-crown-5 and dibenzo-18-crown-6

The reactions of benzo-15-crown-5 and dibenzo-18-crown-6 with 1 equiv. of [(mes)Ru(MeNO₂)₃]²⁺ (mes = 1,3,5-C₆H₃Me₃) give the mononuclear complexes [(mes)Ru(η⁶-benzo-15-crown-5)]²⁺ (1) and [(mes)Ru(η⁶-dibenzo-18-crown-6)]²⁺ (2) in 50% yield. Similar reaction with 2 equiv. of [(mes)Ru(MeNO₂)₃]²⁺ produces the dinuclear complex [(μ-η⁶:η⁶-dibenzo-18-crown-6)Ru₂(mes)₂]⁴⁺ (3) in 96% yield as a 2:3 mixture of cis- and trans-isomers. Structures of 2(OTf)₂ and trans-3(OTf)₄ were confirmed by X-ray diffraction. The NMR titration showed that mononuclear dications 1 and 2 bind Na⁺ ion less effective (K_a = 600 and 250 M^-1) than free benzo-15-crown-5 and dibenzo-18-crown-6 (K_a = 2 × 10⁵ and 5 × 10⁶ M⁻¹). The dinuclear tetracation 3 does not bind Na⁺ within measurable limits of NMR titration method. The electrochemical behaviour of complexes 1-3 was studied in propylene carbonate solution. They exhibit a partially chemically reversible Ru(II)/Ru(I) reduction, which in the case of the dinuclear complex 3 proceeds through two slightly separated steps. The redox activity of the complexes is substantially unaffected by the presence of sodium ion.     

Synthesis of a novel bistriazene reagent 4,4′-bis[3-(4-phenylthiazol-2-yl)triazenyl]biphenyl and its highly sensitive color reaction with mercury(II)

We report the synthesis of a novel bistriazene, 4,4′-bis(3-(4-phenylthiazol-2-yl)triazenyl)biphenyl (BPTTBP), and its highly sensitive color reaction with Hg²⁺. The new reagent was synthesized in good yield by coupling 2-amino-4-phenylthiazole with 4,4′-biphenyldiamine bisdiazonium salt. Using a blend of surfactants N-cetylpyridinium chloride (CPC) and polyethylene glycol n-octanoic phenyl ether (OP) as a micelle sensitizer, the red colored reagent assembles with Hg²⁺ in pH 9.8 borate buffer according to a 1:1 stoichiometry, forming a blue oligomeric/polymeric chelating complex with a high apparent stability constant (1.1 × 10⁸ M⁻¹). Whereas the maximum absorption of reagent occurs at 510 nm with an extinct coefficient of 1.35 × 10⁴ M⁻¹ cm⁻¹, the complex absorbs at 611 nm, with an apparent extinct coefficient of 1.04 × 10⁵ M⁻¹ cm⁻¹. Beer's law is obeyed in the range of 0-15 μg/25 mL Hg²⁺, and Sandell's sensitivity is 1.92 × 10⁻³ μg/cm². In the presence of thiourea and Na₄P₂O₇ as masking agents, the method was found free from interferences of foreign ions commonly occurring with mercury. The optimized protocol has been successfully applied to spectrophotometric determination of mercury in waste water samples. The features of the new reagent associated with its special structure were discussed, and an unprecedented “domino effect” was proposed to account for its unique chelating stoichiometry with Hg²⁺.     

A new high-speed hollow fiber based liquid phase microextraction method using volatile organic solvent for determination of aromatic amines in environmental water samples prior to high-performance liquid chromatography

A new and fast hollow fiber based liquid phase microextraction (HF-LPME) method using volatile organic solvents coupled with high-performance liquid chromatography (HPLC) was developed for determination of aromatic amines in the environmental water samples. Analytes including 3-nitroaniline, 3-chloroaniline and 4-bromoaniline were extracted from 6 mL basic aqueous sample solution (donor phase, NaOH 1 mol L⁻¹) into the thin film of organic solvent that surrounded and impregnated the pores of the polypropylene hollow fiber wall (toluene, 20 μL), then back-extracted into the 6 μL acidified aqueous solution (acceptor phase, HCl 0.5 mol L⁻¹) in the lumen of the two-end sealed hollow fiber. After the extraction, 5 μL of the acceptor phase was withdrawn into the syringe and injected directly into the HPLC system for the analysis. The parameters influencing the extraction efficiency including the kind of organic solvent and its volume, composition of donor and acceptor phases and the volume ratio between them, extraction time, stirring rate, salt addition and the effect of the analyte complexation with 18-crown-6 ether were investigated and optimized. Under the optimal conditions (donor phase: 6 mL of 1 mol L⁻¹ NaOH with 10% NaCl; organic phase: 20 μL of toluene; acceptor phase: 6 μL of 0.5 mol L⁻¹ HCl and 600 m mol L⁻¹ 18-crown-6 ether; pre-extraction and back-extraction times: 75 s and 10 min, respectively; stirring rate: 800 rpm), the obtained EFs were between 259 and 674, dynamic linear ranges were 0.1-1000 μg L⁻¹ (R > 0.9991), and also the limits of detection were in the range of 0.01-0.1 μg L⁻¹. The proposed procedure worked very well for real environmental water samples with microgram per liter level of the analytes, and good relative recoveries (91-102%) were obtained for the spiked sample solutions.     

A method for rapid screening of interactions of pharmacologically active compounds with albumin

We determine the association constants for ligand–protein complex formation using the flow injection method. We carry out the measurements at high flow rates (F = 1 mL min⁻¹) of a carrier phase. Therefore, determination of the association constant takes only a few minutes. Injection of 1 nM of the ligand (10 μL of 1 μM concentration of the ligand solution) is sufficient for a single measurement. This method is tested and verified for a number of complexes of selected drugs (cefaclor, etodolac, sulindac) with albumin (BSA). We obtain K = 4.45 × 10³ M⁻¹ for cefaclor, K = 1.00 × 10⁵ M⁻¹ for etodolac and K = 1.03 × 10⁵ M⁻¹ for sulindac in agreement with the literature data. We also determine the association constants of 20 newly synthesized 3β- and 3α-aminotropane derivatives with potential antipsychotic activity – ligands of 5-HT_1A, 5-HT_2A and D₂ receptors with the albumin. Results of the studies reported here indicate that potential antipsychotic drugs bind weakly to the transporter protein (BSA) with K ≈ 10²–10³ M⁻¹. Our method allows measuring K in a wide range of values (10²–10⁹ M⁻¹). This range depends only on the solubility of the ligand and sensitivity of the detector.     

New potentiometric sensors for creatinine

Three main types of creatinine potentiometric membrane sensors are described. They are based on the use of dibenzo-30-crown-10 (DB30C10) with potassium tetrakis(p-chlorophenyl)borate type (I), dibenzo-30-crown-10 alone type (II), and potassium tetrakis(p-chlorophenyl)borate alone type (III), incorporating in poly(vinyl chloride) matrix membrane plasticized with either o-nitrophenyl octyl ether or dioctylphthalate. The sensors are used for quantification of creatinine after soaking the membranes in 0.1 M creatinine solution for 2 days. The sensors show almost the same potentiometric response characteristics. Sensor type (I) exhibits Nernstian responses over a concentration range of 5.0 × 10⁻⁵ mol l⁻¹-1.0 × 10⁻² mol l⁻¹ creatinine with cationic slopes of 59.5 ± 0.1 and 60 ± 0.2 mV decade⁻¹ and detection limits of 1.1 × 10⁻⁵ mol l⁻¹ and 8 × 10⁻⁶ mol l⁻¹ creatinine, over the pH range of 3.5-6.5 and 3.5-7.0, for o-NPOE and DOP solvent mediators, respectively. Sensor type (II) displays Nernstian responses over a concentration range of 6.0 × 10⁻⁵ mol l⁻¹-1.0 × 10⁻² mol l⁻¹ creatinine with cationic slopes of 60.0 ± 0.1 and 65.0 ± 0.2 mV decade⁻¹ and detection limits of 1.5 × 10⁻⁵ mol l⁻¹ and 1.4 × 10⁻⁵ mol l⁻¹ creatinine over the pH range of 2.6-6.2 and 2.5-6.0, for o-NPOE and DOP solvent mediators, respectively. Sensor type (III) shows Nernstian responses over a concentration range of 7.0 × 10⁻⁵ mol l⁻¹-1.0 × 10⁻² mol l⁻¹ creatinine with cationic slopes of 60 ± 0.1 and 62.0 ± 0.2 mV decade⁻¹ and detection limits of 2.7 × 10⁻⁵ mol l⁻¹ and 2.0 × 10⁻⁵ mol l⁻¹ creatinine over the pH range of 2.5-6.0, for o-NPOE and DOP solvent mediators, respectively. The response times of the sensors for 10⁻³ mol l⁻¹ creatinine solution are instantaneous (4-10 s). The sensors show long-term stability with life span of ∼6 months. The sensors are used for determination of serum creatinine of rats (Rattus Norvigicus) with mean R.S.D. of 2.62%, and the results agreed well with the Jaffe kinetic method.     

Oxidation of substituted pyridines by dimethyldioxirane: kinetics and solvent effects

The oxidation of a series of substituted pyridines by dimethyldioxirane (1) produced the expected N-oxides in quantitative yields. The second order rate constants (k₂) for the oxidation of a series of substituted pyridines (2a-g) by dimethyldioxirane were determined in dried acetone at 23 °C. An excellent correlation with Hammett sigma values was found (ρ = −2.91, r = 0.995). Kinetic studies for the oxidation of 4-trifluoromethylpyridine by 1 were carried out in the following dried solvent systems: acetone (k₂ = 0.017 M⁻¹ s⁻¹), carbon tetrachloride/acetone (7:3; k₂ = 0.014 M⁻¹ s⁻¹), acetonitrile/acetone (7:3; k₂ = 0.047 M⁻¹ s⁻¹), and methanol/acetone (7:3; k₂ = 0.68 M⁻¹ s⁻¹). Kinetic studies of the oxidation of pyridine by 1 versus mole fraction of water in acetone [k₂ = 0.78 M⁻¹ s⁻¹ (χ = 0) to k₂ = 11.1 M⁻¹ s⁻¹ (χ = 0.52)] were carried out. The results showed the reaction to be very sensitive to protic, polar solvents.     

Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides

Heat capacity and enthalpy increments of ternary bismuth tantalum oxides Bi₄Ta₂O₁₁, Bi₇Ta₃O₁₈ and Bi₃TaO₇ were measured by the relaxation time method (2-280 K), DSC (265-353 K) and drop calorimetry (622-1322 K). Temperature dependencies of the molar heat capacity in the form C_pm=445.8+0.005451T−7.489×10⁶/T² J K⁻¹ mol⁻¹, C_pm=699.0+0.05276T−9.956×10⁶/T² J K⁻¹ mol⁻¹ and C_pm=251.6+0.06705T−3.237×10⁶/T² J K⁻¹ mol⁻¹ for Bi₃TaO₇, Bi₄Ta₂O₁₁ and for Bi₇Ta₃O₁₈, respectively, were derived by the least-squares method from the experimental data. The molar entropies at 298.15 K, S°_m(298.15 K)=449.6±2.3 J K⁻¹ mol⁻¹ for Bi₄Ta₂O₁₁, S°_m(298.15 K)=743.0±3.8 J K⁻¹ mol⁻¹ for Bi₇Ta₃O₁₈ and S°_m(298.15 K)=304.3±1.6 J K⁻¹ mol⁻¹ for Bi₃TaO₇, were evaluated from the low-temperature heat capacity measurements.     

Simultaneous screening analysis of multiple beta-blockers in urine by gas chromatography-mass spectrometry in selected ion monitoring mode

A rapid screening procedure is described for the simultaneous determination of 13 β-blockers in urine at the range of 0.010-1.0 μg mL⁻¹. The procedure involves N-ethoxycarbonyl (EOC) derivatization of β-blockers in urine sample, followed by extraction and further conversion to trimethylsilyl (TMS) derivatives for the analysis by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode (GC-SIM-MS). The characteristic fragment ions at m/z 260 and m/z 144, and [M − 15]⁺ ions permitted sensitive and selective detection of most of the β-blockers in the presence of co-extracted urinary amino alcohols at much higher levels. The whole procedure of EOC/TMS derivatization with subsequent GC-SIM-MS analysis was linear (r ≥ 0.9988). The LODs were varied from 0.03 to 2.7 ng mL⁻¹. The ranges of precision (%relative standard deviation) and accuracy (%relative error) of the overall procedure at two different added amounts (0.02 and 0.5 μg mL⁻¹) in urine matrix varied from 1.3 to 9.4 and from −9.6 to 9.7, respectively. The recoveries were measured to be ranged from 90.4 to 109.7%.     

Series of compositions Bi2(M′xM1−x)4O9 (M′, M=Al, Ga, Fe; 0≤x≤1) with mullite-type crystal structure: Synthesis, characterization and O/O exchange experiment

Series of compositions Bi₂(M′_xM_1−x)₄O₉ with x=0.0, 0.1,…, 1.0 and M′/M=Ga/Al, Fe/Al and Fe/Ga were synthesized by dissolving appropriate amounts of corresponding metal nitrate hydrates in glycerine, followed by gelation, calcination and final heating at 800 °C for 24 h. The new compositions with M′/M=Ga/Al form solid-solution series, which are isotypes to the two other series M′/M=Fe/Al and Fe/Ga. The XRD data analysis yielded in all cases a linear dependence of the lattice parameters related on x. Rietveld structure refinements of the XRD patterns of the new compounds, Bi₂(Ga_xAl_1−x)₄O₉ reveal a preferential occupation of Ga in tetrahedral site (4 h). The IR absorption spectra measured between 50 and 4000 cm⁻¹ of all systems show systematic shifts in peak positions related to the degree of substitution. Samples treated in ¹⁸O₂ atmosphere (16 h at 800 °C, 200 mbar, 95% ¹⁸O₂) for ¹⁸O/¹⁶O isotope exchange experiments show a well-separated IR absorption peak related to the M-¹⁸O_c-M vibration, where O_c denotes the common oxygen of two tetrahedral type MO₄ units. The intensity ratio of M-¹⁸O_c/M-¹⁶O_c IR absorption peaks and the average crystal sizes were used to estimate the tracer diffusion coefficients of polycrystalline Bi₂Al₄O₉ (D=2×10⁻²² m²s⁻¹), Bi₂Fe₄O₉ (D=5×10⁻²¹ m²s⁻¹), Bi₂(Ga/Al)₄O₉ (D=2×10⁻²¹ m²s⁻¹) and Bi₂Ga₄O₉ (D=2×10⁻²⁰ m²s⁻¹).