Competition between transferrin and the serum ligands citrate and phosphate for the binding of aluminum

A key issue regarding the speciation of Al(3+) in serum is how well the ligands citric acid and phosphate can compete with the iron transport protein serum transferrin for the aluminum. Previous studies have attempted to measure binding constants for each ligand separately, but experimental problems make it very difficult to obtain stability constants with the accuracy required to make a meaningful comparison between these ligands. In this study, effective binding constants for Al-citrate and Al-phosphate at pH 7.4 have been determined using difference UV spectroscopy to monitor the direct competition between these ligands and transferrin. The analysis of this competition equilibrium also includes the binding of citrate and phosphate as anions to apotransferrin. The effective binding constants are 10(11.59) for the 1:1 Al-citrate complexes and 10(14.90) for the 1:2 Al-citrate complexes. The effective binding constant for the 1:2 Al-phosphate complex is 10(12.02). No 1:1 Al-phosphate complex was detected. Speciation calculations based on these effective binding constants indicate that, at serum concentrations of citrate and phosphate, citrate will be the primary low-molecular-mass ligand for aluminum. Formal stability constants for the Al-citrate system have also been determined by potentiometric methods. This equilibrium system is quite complex, and information from both electrospray mass spectrometry and difference UV experiments has been used to select the best model for fitting the potentiometric data. The mass spectra contain peaks that have been assigned to complexes having aluminum:citrate stoichiometries of 1:1, 1:2, 2:2, 2:3, and 3:3. The difference UV results were used to determine the stability constant for Al(H(-1)cta)-, which was then used in the least-squares fitting of the potentiometric data to determine stability constants for Al(Hcta)+, Al(cta), Al(cta)2(3-), Al(H(-1)cta)(cta)(4-), Al2(H(-1)cta)2(2-), and Al3(H(-1)cta)3(OH)(4-).     

Synthesis and Evaluation of a Cyclophane Receptor for Acetic Acid

A bicyclic cyclophane ( 2 ) containing one pyridine nitrogen and four amide N-H groups oriented toward the interior of the cavity was synthesized. The binding constants of various carboxylic acids with 2 were measured by UV/Vis spectroscopy. Acetic acid bound to 2 with a K a of 980 - 90 M m 1 in chloroform while branched carboxylic acids showed significantly lower binding. The data indicate that acetic acid was bound within the cavity of 2 . Only one acetic acid binds to two control hosts, whereas 2 shows definitive 1:1 binding. The results suggest that selectivity in the binding of carboxylic acids can be achieved via size constraints dictated by the receptor cavity, and that the same size restrictions lead to only one carboxylic acid bound to the cyclophane. The crystal structure of 2 is reported.     

Complexation of 1,4-bis(pyridinium)butanes by negatively charged carboxylatopillar[5]arene

The binding behavior of substituted 1,4-bis(pyridinium)butane derivatives (X-Py(CH(2))(4)Py-X, X = H, 2-methyl, 3-methyl, 4-methyl, 2,6-dimethyl, 4-pyridyl, and 4-COOEthyl) 1(2+)-7(2+), with negatively charged carboxylatopillar[5]arene (CP5A) has been comprehensively investigated by (1)H NMR and 2D ROESY and UV absorption and fluorescence spectroscopy in aqueous phosphate buffer solution (pH 7.2). The results indicated that the position of the substituents attached on pyridinium ring dramatically affects the association constants and binding modes. 3- and 4-Substituted guests (1(2+), 3(2+), 4(2+), 6(2+), 7(2+)) form [2]pseudorotaxane geometries with CP5A host, giving very large association constants (>10(5) M(-1)), while 2,6-dimethyl-substituted 5(2+) forms external complex with relatively small K(a) values [(2.4 ± 0.3) × 10(3) M(-1)] because the 2,6-dimethylpyridinium unit is too bulky to thread the host cavity. Both of the binding geometries mentioned above are observed for 2(2+), having one methyl group in the 2-position of pyridinium. Typically, the association constant of [2]pseudorotaxane 1(2+)?CP5A exceeds 10(6) M(-1) in water, which is significantly higher than those of previously reported analogues in organic solvents. The remarkably improved complexation of bis(pyridinium) guests by the anionic host was due to electrostatic attraction forces and hydrophobic interactions.     

A molecular flytrap for the selective binding of citrate and other tricarboxylates in water

The synthesis and binding properties of a new tricationic guanidiniocarbonyl pyrrole receptor 7 are described. Receptor 7 binds citrate 9 and other tricarboxylates such as trimesic acid tricarboxylate 8 with unprecedented high association constants of K(assoc) > 10(5) M(-1) in water as determined by UV and fluorescence tritration studies. According to NOESY experiments and molecular modeling calculations, the tricarboxylates are bound within the inner cavity of receptor 7 by ion pairing between the carboxylate groups and the guanidiniocarbonyl pyrrole moieties, favored by the nonpolar microenvironment of the cavity. Hence, receptor 7 can be regarded as a molecular flytrap. In the case of the aromatic tricarboxylate 8, additional aromatic interactions further strengthen the complex. The complexes with the tricarboxylates are so strong that even the presence of a large excess of competing anions or buffer salts does not significantly affect the association constant. For example, the association constant for citrate changes only from K(assoc) = 1.6 x 10(5) M(-1) in pure water to K(assoc) = 8.6 x 10(4) M(-1) in the presence of a 170-fold excess of bis-tris buffer and a 1000-fold excess of chloride. This makes 7 one of the most efficient receptors for the binding of citrate in aqueous solvents reported thus far.     

Molecular Recognition of Nucleotides in Water by Scorpiand‐Type Receptors Based on Nucleobase Discrimination

The detection of nucleotides is of crucial importance because they are the basic building blocks of nucleic acids. Scorpiand‐based polyamine receptors functionalized with pyridine or anthracene units are able to form stable complexes with nucleotides in water, based on coulombic, π–π stacking, and hydrogen‐bonding interactions. This behavior has been rationalized by means of an exploration with NMR spectroscopy and DFT calculations. Binding constants were determined by potentiometry. Fluorescence spectroscopy studies have revealed the potential of these receptors as sensors to effectively and selectively distinguish guanosine‐5′‐triphosphate (GTP) from adenosine‐5′‐triphosphate (ATP).     

Voltammetric and spectroscopic investigations of 4-nitrophenylferrocene interacting with DNA

Cyclic voltammetry (CV) coupled with UV–vis and fluorescence spectroscopy were used to probe the interaction of potential anticancer drug, 4-nitrophenylferrocene (NFC) with DNA. The electrostatic interaction of the positively charged NFC with the anionic phosphate of DNA was evidenced by the findings like negative formal potential shift in CV, ionic strength effect, smaller bathochromic shift in UV–vis spectroscopy, incomplete quenching in the emission spectra and decrease in viscosity. The diffusion coefficients of the free and DNA bound forms of the drug were evaluated from Randles–Sevcik equation. The binding parameters like binding constant, ratio of binding constants (K_red/K_ox), binding site size and binding free energy were determined from voltammetric data. The binding constant was also determined from UV–vis and fluorescence spectroscopy with a value quite close to that obtained from CV.     

Synthesis, optical properties, and LFER analysis of solvent-dependent binding constants of Hamilton-receptor-connected merocyanine chromophores

A merocyanine dye equipped with a Hamilton-receptor unit has been synthesized that enables strong noncovalent binding of other merocyanine dyes bearing barbituric acid acceptor groups by six hydrogen bonds. NMR and UV/vis titration experiments in toluene, chloroform, dichloromethane, dioxane, and THF provide evidence for the formation of 1:1 complexes even in the dipolar solvents. An enhanced binding strength is observed for the more dipolar merocyanine dyes in the head-to-tail assembly structure with binding constants up to >10 (8) M (-1) in toluene. In the present bimolecular complexes two merocyanine chromophores are assembled in a head-to-tail fashion that affords increased dipole moments as demanded for efficient electric field induced poling processes in nonlinear optical and photorefractive polymeric hosts. The solvent dependency of the binding constants for various barbituric acid dye-Hamilton receptor complexes as well as a perylene imide-melamine complex reveals linear free energy relationships (LFER) that allow for an estimation of binding constants larger than 10 (12) M (-1) for Hamilton receptor organized head-to-tail merocyanine bimolecular complexes in aliphatic solvents. It is suggested that such LFER are valuable tools for the estimation of binding constants in solvents where experimental binding constants cannot be determined because of solubility or spectroscopic problems.     

Multinuclear NMR studies of the interaction of metal ions with adenine-nucleotides

It is well-known that metal ion complexes are essential in various biological systems, including those with adenosine nucleotides which are substrates for a large number of enzymatic processes. The interactions of various metal ions with adenosine nucleotides have been intensively studied by multinuclear NMR spectroscopy. Nucleotides are polydentate ligands with various potential binding sites, including nitrogen atoms on the purine base, hydroxyl groups on the ribose sugar, and negatively charged oxygen atoms in the phosphate group. Depending on the experimental conditions (e.g. pH, concentration range, etc.) and on the size and nature of the metal ions, monodentate, or multidentate coordination to these donor atoms are possible. The review focuses on the applications of different NMR techniques in identifying the stoichiometry and the mode of metal binding in complexes formed with the most important adenosine nucleotides, like adenosine-5′-mono-, di- and triphosphates (AMP, ADP and ATP). Ligand exchange dynamics for some metal ion complexes are also presented.     

Interaction of the indoor air pollutant acetone with Degussa P25 TiO2 studied by chemical ionization mass spectrometry

Preventing a build-up of indoor pollutant concentrations has emerged as a major goal in environmental chemistry. Here, we have applied chemical ionization mass spectrometry to study the interaction of acetone, a common indoor air pollutant, with Degussa P25 TiO2, an inexpensive catalyst that is widely used for the degradation of volatile organic compounds into CO2 and water. To better understand the adsorption of acetone onto Degussa P25, the necessary first step for its degradation, the experiments were carried out at room temperature in the absence of UV light. This allowed for the deconvolution of the nonreactive and reactive thermal binding processes on Degussa P25 at acetone partial pressures (10(-7)-10(-4) Torr) commonly found in indoor environments. On average, 30% of the adsorbed acetone is bound irreversibly, resulting in a surface coverage of irreversibly bound acetone of approximately 1 x 10(12) molecules/cm2 at 3-4 x 10(-5) Torr. Equilibrium and dynamic experiments yield a sticking coefficient of approximately 1 x 10(-4) that is independent of the acetone partial pressures examined here. Equilibrium binding constants and free energies of adsorption are reported.     

Effectiveness of Phosphate Groups in Noncovalent Interactions in Binary Adenosine Nucleotides/Phosphoserine Aqueous Systems

Adduct formation in binary systems of O-phospho-L-serine (Ser-P) with adenosine 5′-monophosphate (AMP), adenosine 5′-diphosphate (ADP) and adenosine 5′-triphosphate (ATP), has been investigated. This study was performed in aqueous solutions using a potentiometric method with computer analysis of the data, together with ¹³C and ³¹P NMR spectroscopic measurements. The overall stability constants of the adducts and the equilibrium constants for their formation have been determined. Ion-dipole and ion-ion interactions have been established to occur in the identified noncovalent complexes. An analysis of the equilibrium constants of the reaction has allowed the determination of the effectiveness of the phosphate groups and donor atoms of heterocyclic rings for molecular complex formation. The potential reaction centers are the atoms N(1) and N(7) from the purine base, the phosphate group of the nucleotides, and the phosphate, carboxyl and amine groups from phosphorylated serine. Sites for the interactions in the bioligands have been found on the basis of an equilibrium constant study and an analysis of the changes in the signal positions of their NMR spectra.     

Studies on the interaction of gallic acid with human serum albumin in membrane mimetic environments

In this study the interaction between gallic acid and human serum albumin (HSA) in AOT/isooctane/water microemulsions was characterized for the first time using fluorescence quenching technique in combination with UV absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) spectroscopy and dynamic light scattering (DLS) technique. In water-surfactant molar ratio (omega(o))=20 microemulsions fluorescence data revealed the presence of one binding site of gallic acid on HSA and its binding constants (K) were (1.18+/-0.02)x10(4), (1.13+/-0.02)x10(4), (1.03+/-0.02)x10(4), (0.95+/-0.02)x10(4), (0.87+/-0.02)x10(4) and (0.82+/-0.03)x10(4)M(-1) at 282, 289, 296, 303, 310 and 317 K, respectively. The affinities in microemulsions were much higher than that in buffer solution. FT-IR and CD data suggested that the protein conformations were altered with the reductions of alpha-helices from 54-56% for free HSA in buffer to 40-41% for free HSA in microemulsion. After binding with gallic acid, the alpha-helices of HSA in microemulsion increased 2-7% for different drug-protein molar ratio. The thermodynamic functions standard enthalpy (Delta H(0)) and standard entropy (DeltaS(0)) for the reaction were calculated to be -8.10 kJ mol(-1) and 49.42 J mol(-1)K(-1). These results indicated that gallic acid bound to HSA mainly by hydrophobic interaction and electrostatic interaction in microemulsions. In addition, the displacement experiments confirmed that gallic acid could bind to the site I of HSA, which was approved by the molecular modeling study. Furthermore, the DLS data suggested that HSA may locate at the interface of the microemulsion and gallic acid could interact with them.     

Interplay of p-sulfonatocalix[4]arene and crown ethers en route to molecular capsules and "Russian dolls"

Diffusion-ordered (1)H NMR spectroscopy techniques have been used to determine the binding strength of p-sulfonatocalix[4]arene (SO(3)[4]) towards a number of charged crown ether species in aqueous conditions. For several (doubly) charged (di)azacrown ethers, all were bound by SO(3)[4] either well or very well with binding constants between 5.1 x 10(2)-9.9 x 10(5) M(-1). These results correlate with, and thus explain the phenomenon of rapid capture of azacrown ethers in molecular capsules based on p-sulfonatocalix[4]arene and lanthanide metals. Similarly, the formation of "Russian doll" superanions in the solution phase is also elucidated. These superanions have been shown to selectively crystallise particular polynuclear aquated metal ions from mixtures in the aqueous phase. Neutral [18]crown-6 is not bound by p-sulfonatocalix[4]arene and displays a binding constant of 0 M(-1). When sodium [18]crown-6 is examined in a similar fashion, binding by SO(3)[4] is observed in solution with K(a) approximately 3.1 x 10(3) M(-1).     

An extraction-based assay for neutral anionophores: the measurement of high binding constants to steroidal receptors in a nonpolar solvent

The extraction-based protocol for measuring binding constants, developed by Cram and co-workers, has been extended for use with anionic substrates. The method is especially useful for high-affinity receptors, allowing very high binding constants to be measured in nonpolar solvents. Distribution constants K(d) between chloroform and water have been obtained for tetraethylammonium chloride and bromide, thus calibrating the method for these two substrates. Application to steroidal podands 5-9 has confirmed the ability of electron-withdrawing groups to enhance hydrogen-bond donor capabilities. Binding constants of approximately 3 x 10(7) M(-1) have been measured for the most powerful receptor 7. An X-ray crystal structure of 15, the methyl ester analogue of 7, reveals a well-defined binding site preorganised for anion recognition.     

Fluorescence Quenching and Binding Interaction of l0-Methylacridinium Iodide to Nucleic Acids

Interaction of 10‐methylacridinium iodide (MAI) as fluorescence probe with nucleobases, nucleosides and nucleic acids has been studied by UV‐visible absorption and fluorescence spectroscopy. It was found that fluorescence of MAI is strongly quenched by the nucleobases, nucleosides and nucleic acids, respectively. The quenching follows the Stern‐Volmer linear equation. The fluorescence quenching rate constant (k_q) was measured to be 10^9‐10¹⁰ (L/mol)/s within the range of diffusion‐controlled rate limit, indicating that the interaction between MAI and nucleic acid and their precursors is characteristic of electron transfer mechanism. In addition, the binding interaction model of MAI to calf thymus DNA (ct‐DNA) was further investigated. Apparent hypochromism in the absorption spectra of MAI was observed when MAI binds to ct‐DNA. Three spectroscopic methods, which include (1) UV spectroscopy, (2) fluorescence quenching of MAI, (3) competitive dual‐probe method of MAI and ethidium bromide (EB), were utilized to determine the affinity binding constants (K) of MAI and ct‐DNA. The binding constants K obtained from the above methods gave consistent data in the same range (1.0–5.5) × 10⁴L/mol, which lend credibility to these measurements. The binding site number was determined to be 1.9. The influence of thermal denaturation and phosphate concentration on the binding was examined. The binding model of MAI to ct‐DNA including intercalation and outside binding was investigated.     

Potentiometric, luminescence and NMR study of the interaction of Eu with glyceryl phosphates

Complexation of europium(III) with glyceryl-1- and -2-phosphates has been studied by metal ion luminescence, ¹H and ¹³C NMR spectroscopy and potentiometry. From the luminescence and NMR studies, the formation of a 1:1 inner-sphere complex, in which the glyceryl phosphate is directly bound to the metal, is confirmed. Similar apparent binding constants at pH 2 were obtained by the three methods. Values obtained by NMR at pH 2 are 53 M⁻¹ and 12 M⁻¹ for glyceryl-1- and -2-phosphate, respectively. By comparison with literature data on related systems it is suggested that the ligands bind through the phosphate group. To obtain structural information from the NMR data, complexation has also been studied with the lanthanide ions Dy(III), Er(III) and Gd(III) using both chemical shift and relaxation data. From this, metal-proton distance ratios have been calculated. Comparison of ¹H and ¹³C NMR spectral data in the presence of paramagnetic lanthanides suggests conformational equilibria in the solutions. From the potentiometric studies, global formation constants have been determined, and speciation diagrams obtained over the pH range 1.5pH7.0 for ligand/metal ratios of 1 and 30. Implications of these results on lanthanide induced fusion of phospholipid membranes are discussed.     

Strong binding affinity of a zinc-porphyrin-based receptor for halides through the cooperative effects of quadruple C-H hydrogen bonds and axial ligation

A new type of host compound (1), tetraphenyl zinc-porphyrin (ZnTPP) that contains four triazole groups at the ortho-position of each phenyl group, has been synthesized and characterized by using (1)H, (13)C NMR, and MALDI-TOF-MS analyses. The host-guest complex formation between 1 and halides was investigated by using (1)H NMR spectroscopy in [D(6)]DMSO. The triazole, benzyl, and phenylene proton signals were shifted upfield by the addition of halides in the form of tetrabutylammonium salts, which implies that the triazole protons in 1 are allocated very closely to the porphyrin ring and are directed toward the binding pocket over the porphyrin ring during the formation of hydrogen bonds. The UV/Vis absorption spectra showed that both the Soret and Q band absorptions of 1 underwent a strong redshift due to the addition of halides. Compound 1 exhibited surprisingly strong binding affinities for the halides, where the association constants for Cl(-), Br(-), and I(-) binding were estimated to be larger than 10(8), 1.79×10(7), and 1.84×10(5) M(-1), respectively. The UV/Vis absorption changes and the result of competitive titration using 4-tert-butylpyridine indicated that the cooperative effects of axial coordination and C-H···X hydrogen bond interactions resulted in the strong binding affinity of 1 to halides.     

Molecular Ionics of Anion Receptor Molecules: A Microcalorimetric Study

The coordination of divalent and monovalent inorganic anions to synthetic polyammonium receptors is investigated in aqueous solution around neutral pH by titration calorimetry and NMR spectroscopy. High-affinity 1:1 complexes are formed by a pyrrole type cryptand (1) with sulfate and phosphate, characterized by association constants of almost 107 M^-1. Affinities close to 105 M^-1 are found for polyazacryptands (3 and 4) exhibiting F^-/Cl^- selectivity. The binding affinities and the anion selectivities are mainly caused by the charges of ligands and anions, which is discussed on the basis of simple calculations of the electrostatic contribution to the anion/receptor interactions. The binding of all investigated anions is exothermic at 298.2 K. The contribution of the large negative ΔH values to the free energy of anion binding of the pyrrole type ligand is partially compensated by marked negative ΔS values. These unfavorable entropic contributions are attributed to the additional inclusion of water molecules in the anion/receptor complexes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Multiple recognition of barbiturate guests by Hamilton-receptor-functionalized dendrimers

The well-known unsubstituted "Hamilton receptor" was monofunctionalized with an amino group and attached at the periphery of poly(propyleneamine) dendrimers through the use of an activated ester. Four generations of Hamilton-receptor-functionalized dendrimers (HR-dendrimers) were synthesized and characterized by (1)H and (13)C NMR spectroscopy and MALDI-TOF mass spectrometry. The photophysical properties of the HR-dendrimers were investigated by UV/Vis as well as with steady-state and time-resolved fluorescence spectroscopy. The dendrimers were used as multivalent hosts for the barbiturate guests Barbital (7) and [Re(Br)(CO)(3)(barbi-bpy)] (8; barbi-bpy=5-[4-(4'-methyl)-2,2'-bipyridyl]methyl-2,4,6-(1 H,3 H,5 H)-pyrimidinetrione). The stable adducts formed between the dendritic architectures (the hosts) and the barbiturate guests 7 and 8 were investigated by (1)H NMR spectroscopy and photophysical methods. The binding constants of the barbiturate guests for binding to reference compound 2 (with a single receptor unit) in chloroform were found to be 1.4 x 10(3) M(-1) and 1.5 x 10(5) M(-1) for 7 and 8, respectively. Binding of 7 to the dendrimers enhances the weak emission of the Hamilton receptor. This increase in emission is also generation dependent; it was found to be most pronounced in the case of 2 and the least in the case of the fourth-generation dendrimer 6. The unexpected increase in the quantum yield of emission from the HR-dendrimers with increasing generation could be caused by the rather rigid conformation of the Hamilton receptors in later-generation compounds, which is a result of intramolecular aggregation and steric hindrance at the periphery of the dendrimer. The photoinduced energy transfer from the excited state of the HR-dendrimers to the lower-lying excited state of the guest 8 was used to probe the formation of host-guest complexes. The rate of energy transfer was calculated to be 3.6 x 10(10) s(-1). Energy transfer in 2 subset 8 only occurred in the presence of a strong base, which shows that the basic amine core in the HR-dendrimers is crucial for this photoinduced process. The binding of 8 to the dendrimers is completely reversible: 8 can be exchanged with a competitive guest such as 7 and the emission of the HR-dendrimer is restored.     

A new strategy for the design of water-soluble synthetic receptors: specific recognition of DNA intercalators and diamines

Water-soluble zinc bisporphyrin receptors 1 and 2 having two Lewis acidic sites (zinc) in the hydrophobic environment consisting of alkyl chains and a bisporphyrin framework, and covered with hydrophilic exterior (twelve or eighteen carboxyl groups) were prepared. The receptors show high affinity for diamines and DNA intercalators in water where the binding constants K(a) are of the order of 10(7) and 10(8) M(-1), respectively. Diamines and DNA intercalators are bound to the receptor through different mechanisms. Diamines are bound through hydrophobic interactions and zinc-nitrogen interactions, while DNA intercalators are bound through hydrophobic interactions and charge-transfer interactions. Flexible alkyl chains can make van der Waals contact with guests and create a hydrophobic environment around the bound guest by an induced-fit-type mechanism. For the binding of DNA intercalators, the following features are noteworthy: 1). Binding constants are similar between the zinc porphyrins and zinc-free porphyrins; 2). the binding constant is larger for the guest having the lower LUMO; this indicates the important contribution of charge-transfer interactions to binding; 3). the hydrophobic and cationic nature of DNA intercalators is substantially important, and 4). higher ionic strength reduced the binding affinities; this shows a moderate contribution of electrostatic interactions. The conformational instability of the receptors also contributes to the tight binding: hydrophobic and electrostatic interactions cannot both be favorable at the same time in the guest-free receptor. Enthalpy-entropy compensation observed for the binding of diamines and DNA intercalators is characterized by a relatively small slope (alpha=0.74) and a large intercept (beta=7.75 kcal mol(-1)) in the DeltaH degrees versus TDeltaS degrees plot; this shows that a conformational change of receptors and a significant desolvation occur upon binding. The receptor can competitively bind to propidium iodide to deprive DNA of the intercalated propidium iodide. These features of water-soluble receptors consisting of a rigid framework and flexible side chains with a large solvent-accessible area are in contrast to highly preorganized rigid receptors, and they can provide useful guidelines for rational design of induced-fit artificial receptors in water.     

Conversion of molecular information by luminescent nanointerface self-assembled from amphiphilic Tb(III) complexes

A novel amphiphilic Tb(3+) complex (TbL(+)) having anionic bis(pyridine) arms and a hydrophobic alkyl chain is developed. It spontaneously self-assembles in water and gives stable vesicles that show sensitized luminescence of Tb(3+) ions at neutral pH. This TbL(+) complex is designed to show coordinative unsaturation, i.e., water molecules occupy some of the first coordination spheres and are replaceable upon binding of phosphate ions. These features render TbL(+) self-assembling receptor molecules which show increase in the luminescence intensity upon binding of nucleotides. Upon addition of adenosine triphosphate (ATP), significant amplification of luminescent intensity was observed. On the other hand, ADP showed moderately increased luminescence and almost no enhancement was observed for AMP. Very interestingly, the increase in luminescence intensity observed for ATP and ADP showed sigmoidal dependence on the concentration of added nucleotides. It indicates positive cooperative binding of these nucleotides to TbL(+) complexes preorganized on the vesicle surface. Self-assembly of amphiphilic Tb(3+) receptor complexes provides nanointerfaces which selectively convert and amplify molecular information of high energy phosphates linked by phosphoanhydride bonds into luminescence intensity changes.