Lanthanide ions possess fascinating optical properties and their discovery, first industrial uses and present high technological applications are largely governed by their interaction with light. Lighting devices (economical luminescent lamps, light emitting diodes), television and computer displays, optical fibres, optical amplifiers, lasers, as well as responsive luminescent stains for biomedical analysis, medical diagnosis, and cell imaging rely heavily on lanthanide ions. This critical review has been tailored for a broad audience of chemists, biochemists and materials scientists; the basics of lanthanide photophysics are highlighted together with the synthetic strategies used to insert these ions into mono- and polymetallic molecular edifices. Recent advances in NIR-emitting materials, including liquid crystals, and in the control of luminescent properties in polymetallic assemblies are also presented. (210 references.)

Taking advantage of luminescent lanthanide ions

Fluorogenic and chromogenic chemosensors and reagents for anions.

The miniaturization of components used in the construction of working devices is being pursued currently by the large-downward (top-down) fabrication. This approach, however, which obliges solid-state physicists and electronic engineers to manipulate progressively smaller and smaller pieces of matter, has its intrinsic limitations. An alternative approach is a small-upward (bottom-up) one, starting from the smallest compositions of matter that have distinct shapes and unique properties-namely molecules. In the context of this particular challenge, chemists have been extending the concept of a macroscopic machine to the molecular level. A molecular-level machine can be defined as an assembly of a distinct number of molecular components that are designed to perform machinelike movements (output) as a result of an appropriate external stimulation (input). In common with their macroscopic counterparts, a molecular machine is characterized by 1) the kind of energy input supplied to make it work, 2) the nature of the movements of its component parts, 3) the way in which its operation can be monitored and controlled, 4) the ability to make it repeat its operation in a cyclic fashion, 5) the timescale needed to complete a full cycle of movements, and 6) the purpose of its operation. Undoubtedly, the best energy inputs to make molecular machines work are photons or electrons. Indeed, with appropriately chosen photochemically and electrochemically driven reactions, it is possible to design and synthesize molecular machines that do work. Moreover, the dramatic increase in our fundamental understanding of self-assembly and self-organizational processes in chemical synthesis has aided and abetted the construction of artificial molecular machines through the development of new methods of noncovalent synthesis and the emergence of supramolecular assistance to covalent synthesis as a uniquely powerful synthetic tool. The aim of this review is to present a unified view of the field of molecular machines by focusing on past achievements, present limitations, and future perspectives. After analyzing a few important examples of natural molecular machines, the most significant developments in the field of artificial molecular machines are highlighted. The systems reviewed include 1) chemical rotors, 2) photochemically and electrochemically induced molecular (conformational) rearrangements, and 3) chemically, photochemically, and electrochemically controllable (co-conformational) motions in interlocked molecules (catenanes and rotaxanes), as well as in coordination and supramolecular complexes, including pseudorotaxanes. Artificial molecular machines based on biomolecules and interfacing artificial molecular machines with surfaces and solid supports are amongst some of the cutting-edge topics featured in this review. The extension of the concept of a machine to the molecular level is of interest not only for the sake of basic research, but also for the growth of nanoscience and the subsequent development of nanotechnology.

Artificial Molecular Machines.

Artificial Organic Host Molecules for Anions

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Physical Factors in Anion Separations (B. Moyer & P. Bonnesen). Historical View on the Development of Anion Coordination Chemistry (B. Dietrich & M. Hosseini). Natural Anion Receptors: Anion Recognition by Proteins (S. Mangani & M. Ferraroni). Artificial Anion Hosts: Concepts for Structure and Guest Binding (F. Schmidtchen). Structural and Topological Aspects of Anion Coordination (J. Atwood & J. Steed). Thermodynamics of Anion Complexation (A. Bianchi & E. Garcia-Espana). Electrochemical Aspects of Anion Chemistry (A. Carbo). Photochemistry and Photophysics of Supramolecular Systems Containing Anions (L. Moggi & M. Manfrin). Anion Binding Receptors: Theoretical Studies (J. Wiorkiewicz-Kuczera & K. Bowman-James). Application Aspects Involving the Supramolecular Chemistry of Anions (J. Sessler, et al.). Supramolecular Catalysis of Phosphoryl Anion Transfer Processes (M. Hasseini). Index.

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Supramolecular chemistry of anions

Anion coordination chemistry in aqueous solution of polyammonium receptors

Thermodynamic aspects of the polyazacycloalkane complexes with cations and anions

Proton Coordination by Polyamine Compounds in Aqueous Solution

The ligand [30]aneN6O4 (L1) binds two Zn(II) in aqueous solution. The stability constants of the L1 complexes have been determined at 308.1 K by means of potentiometric measurements. Dinuclear monohydroxo [Zn2L1OH]3+ and dihydroxo [Zn2L1(OH)2]2+ complexes are formed in aqueous solution from neutral to alkaline pH. The kinetics of promoted hydrolysis of p-nitrophenyl acetate (NA) was studied. Both hydroxo species promote p-nitrophenyl acetate (NA) hydrolysis at 298.1 K with second-order kinetics. The activity of these species in NA hydrolysis is similar to that found for the mononuclear L2−Zn-OH+ complex (L2 = [15]aneN3O2), indicating that the hydrolytic process takes place via a simple bimolecular mechanism. The hydrolysis rate of bis(p-nitrophenyl) phosphate (BNP) was measured in aqueous solution at 308.1 K in the presence of the L1 and L2 zinc complexes. The hydrolysis rate of BNP is increased almost 10-fold by the dinuclear [Zn2L1(OH)2]2+ complex with respect to the mononuclear L2−Zn-OH+ one. This resu...

Carboxy and Phosphate Esters Cleavage with Mono- and Dinuclear Zinc(II) Macrocyclic Complexes in Aqueous Solution. Crystal Structure of [Zn2L1(μ-PP)2(MeOH)2](ClO4)2 (L1 = [30]aneN6O4, PP- = Diphenyl Phosphate)

Antonio Bianchi

Papers

Supramolecular chemistry of anions

Anion coordination chemistry in aqueous solution of polyammonium receptors

Thermodynamic aspects of the polyazacycloalkane complexes with cations and anions

Proton Coordination by Polyamine Compounds in Aqueous Solution

Carboxy and Phosphate Esters Cleavage with Mono- and Dinuclear Zinc(II) Macrocyclic Complexes in Aqueous Solution. Crystal Structure of [Zn2L1(μ-PP)2(MeOH)2](ClO4)2 (L1 = [30]aneN6O4, PP- = Diphenyl Phosphate)