Quantum receiver enhanced by adaptive learning.

Quantum receivers aim to effectively navigate the vast quantum-state space to endow quantum information processing capabilities unmatched by classical receivers. To date, only a handful of quantum receivers have been constructed to tackle the problem of discriminating coherent states. Quantum receivers designed by analytical approaches, however, are incapable of effectively adapting to diverse environmental conditions, resulting in their quickly diminishing performance as the operational complexities increase.

Calcium-binding properties of wild-type and EF-hand mutants of S100B in the presence and absence of a peptide derived from the C-terminal negative regulatory domain of p53.

S100B is a dimeric Ca(2+)-binding protein that undergoes a 90 +/- 3 degrees rotation of helix 3 in the typical EF-hand domain (EF2) upon the addition of calcium. The large reorientation of this helix is a prerequisite for the interaction between each subunit of S100B and target proteins such as the tumor suppressor protein, p53. In this study, Tb(3+) was used as a probe to examine how binding of a 22-residue peptide derived from the C-terminal regulatory domain of p53 affects the rate of Ca(2+) ion dissociation.

Europium luminescence of EF-hand helix-turn-helix chimeras: impact of pH and DNA-binding on europium coordination.

A series of Eu(III) metallopeptides, designed on the basis of the structural similarity of the helix-turn-helix and EF-hand motifs, have been studied by Eu(III) (7)F(0) --> (5)D(0) excitation spectroscopy. The impact of EF-hand ligand set differences on the hydration number and Eu(III) coordination environment are compared among the peptides. The conditional binding affinities were determined by Eu titration (P3, log K(a) = 6.

Lanthanide complexes of [alpha-2-P2W17O61]10-: solid state and solution studies.

We have isolated the 1:1 Ln:[alpha-2-P2W17O61]10- complexes for a series of lanthanides. The single-crystal X-ray structure of the Eu3+ analogue reveals two identical [Eu(H2O)3(alpha-2-P2W17O61)]7- moieties connected through two Eu-O-W bonds, one from each polyoxometalate unit. An inversion center relates the two polyoxometalate units.

The interaction of MS-325 with human serum albumin and its effect on proton relaxation rates.

MS-325 is a novel blood pool contrast agent for magnetic resonance imaging currently undergoing clinical trials to assess blockage in arteries. MS-325 functions by binding to human serum albumin (HSA) in plasma. Binding to HSA serves to prolong plasma half-life, retain the agent in the blood pool, and increase the relaxation rate of water protons in plasma.

Displacement of Inner-Sphere Water Molecules from Eu(3+) Analogues of Gd(3+) MRI Contrast Agents by Carbonate and Phosphate Anions: Dissociation Constants from Luminescence Data in the Rapid-Exchange Limit.

Europium(III) (7)F(0) --> (5)D(0) excitation spectroscopy is used to determine if the anions carbonate and phosphate present in physiological fluids are able to displace water molecules from the first coordination sphere of Eu(3+) analogues of Gd(3+) MRI contrast agents. A lengthening of the Eu(3+) excited state lifetime in the presence of millimolar concentrations of carbonate or phosphate indicates that water molecules are displaced by an anion. Only those metal complexes that contain negatively charged ligands and more than one water molecule in the first coordination sphere of Eu(3+) have their water molecules displaced by saturating concentrations of carbonate or phosphate.

Lanthanide Complexes of the alpha-1 Isomer of the [P(2)W(17)O(61)](10-) Heteropolytungstate: Preparation, Stoichiometry, and Structural Characterization by (183)W and (31)P NMR Spectroscopy and Europium(III) Luminescence Spectroscopy.

The alpha-1 and alpha-2 [P(2)W(17)O(61)](10)(-) isomers, derivatives of the Wells-Dawson molecule, [alpha-P(2)W(18)O(62)](6)(-), may be useful ligands for stabilizing high-valent metal ions and lanthanides and actinides. However, the potential utility of the [alpha1-P(2)W(17)O(61)](10)(-) ligand has not been realized. Specifically, for the lanthanides, the stoichiometry, structure, and purity of the lanthanide complexes of the [alpha1-P(2)W(17)O(61)](10)(-) isomer are ambiguous.

Effect of Mixed Pendent Groups on the Solution and Catalytic Properties of Europium(III) Macrocyclic Complexes: Bifunctional and Monofunctional Amide and Alcohol Pendents in Septadentate or Octadentate Ligands.

Five new Eu(III) macrocyclic complexes have been prepared and their solution and catalytic properties studied. The Eu(III) complexes with septadentate ligands TRED and NB-TRED dissociate rapidly at pH 7.4, 37 degrees C (TRED = 1,4,7-tris(hydroxyethyl)-1,4,7,10-tetraazacyclododecane, NB-TRED = 1-(nitrobenzyl)-4,7,10-tris(hydroxyethyl)-1,4,7,10-tetraazacyclododecane).

Kinetics of Formation of Ca(2+) Complexes of Acyclic and Macrocyclic Poly(amino carboxylate) Ligands: Bimolecular Rate Constants for the Fully-Deprotonated Ligands Reveal the Effect of Macrocyclic Ligand Constraints on the Rate-Determining Conversions of Rapidly-Formed Intermediates to the Final Complexes.

The apparent bimolecular rate constants, k(1) (M(-)(1) s(-)(1)), for the formation of Ca(2+) complexes of a series of acyclic (edta, egta, cdta) and macrocyclic (dota, teta, do3a) poly(amino carboxylate) ligands were determined in the pH range 7-13 using the fluorescent ligand quin2 in a stopped-flow apparatus to monitor the ligand competition reaction. The k(1) values are observed to reach maximum constant values at high pH, characteristic of reactions involving the fully-deprotonated ligand species. Bimolecular formation constants k(Ca)(L), k(Ca)(HL), and k(Ca)(H)()2(L), characteristic of the reaction of the fully-deprotonated and mono- and diprotonated ligands, respectively, were derived from the pH dependence of the k(1) values.

Kinetics of the Formation of Macrocyclic Polyaminocarboxylate Ligand Complexes: A Laser-Excited Luminescence Study of the Eu(3+)-dtpa-dien System.

Excitation spectroscopy of the (7)F(0) --> (5)D(0) transition of Eu(3+) is used to detect and characterize a kinetic intermediate in the formation of a complex between Eu(3+) and the macrocyclic ligand dtpa-dien (1,4,7-tris(carboxymethyl)-9,17-dioxo-1,4,7,10,13,16-hexaazacyclooctadecane). Both the long-lived intermediate and the final product, [Eu(Hdtpa-dien)(H(2)O)](+), are formed immediately upon mixing the components, as evidenced by separate peaks in the excitation spectrum. The transformation of the intermediate to the final product, monitored by excitation spectroscopy, occurs by both proton-assisted and non-proton-assisted pathways.