Signaling Recognition Events with Fluorescent Sensors and Switches.

The widespread use of controlled molecular-level motion in key natural processes suggests that great rewards could come from bridging the gap between the present generation of synthetic molecular systems, which by and large rely upon electronic and chemical effects to carry out their functions, and the machines of the macroscopic world, which utilize the synchronized movements of smaller parts to perform specific tasks. This is a scientific area of great contemporary interest and extraordinary recent growth, yet the notion of molecular-level machines dates back to a time when the ideas surrounding the statistical nature of matter and the laws of thermodynamics were first being formulated. Here we outline the exciting successes in taming molecular-level movement thus far, the underlying principles that all experimental designs must follow, and the early progress made towards utilizing synthetic molecular structures to perform tasks using mechanical motion. We also highlight some of the issues and challenges that still need to be overcome.

Synthetic molecular motors and mechanical machines.

2.5. Stabilization of IL Emulsions by Nanoparticles 2623 3. Hydrogenations in ILs 2623 3.1. Hydrogenation on IL-Stabilized Nanoparticles 2623 3.1.1. Hydrogenation of 1,3-Butadiene 2623 3.1.2. Hydrogenation of Alkenes and Arenes 2624 3.1.3. Hydrogenation of Ketones 2624 3.2. Homogeneous Catalytic Hydrogenation in ILs 2624 3.3. Hydrogenation of Functionalized ILs 2625 3.3.1. Selective Hydrogenation of Polymers 2625 3.4. Asymmetric Hydrogenations 2626 3.4.1. Enantioselective Hydrogenation 2626 3.5. Role of the ILs Purity in Hydrogenation Reactions 2628

Catalysis in ionic liquids

The brain is a singular organ of unique biological complexity that serves as the command center for cognitive and motor function. As such, this specialized system also possesses a unique chemical composition and reactivity at the molecular level. In this regard, two vital distinguishing features of the brain are its requirements for the highest concentrations of metal ions in the body and the highest per-weight consumption of body oxygen. In humans, the brain accounts for only 2% of total body mass but consumes 20% of the oxygen that is taken in through respiration. As a consequence of high oxygen demand and cell complexity, distinctly high metal levels pervade all regions of the brain and central nervous system. Structural roles for metal ions in the brain and the body include the stabilization of biomolecules in static (e.g., Mg2+ for nucleic acid folds, Zn2+ in zinc-finger transcription factors) or dynamic (e.g., Na+ and K+ in ion channels, Ca2+ in neuronal cell signaling) modes, and catalytic roles for brain metal ions are also numerous and often of special demand.

Metals in Neurobiology: Probing Their Chemistry and Biology with Molecular Imaging

The increase in atmospheric carbon dioxide is linked to climate changes; hence there is an urgent need to reduce the accumulation of CO2 in the atmosphere. The utilization of CO2 as a raw material in the synthesis of chemicals and liquid energy carriers offers a way to mitigate the increasing CO2 buildup. This review covers six important CO2 transformations namely: chemical transformations, photochemical reductions, chemical and electrochemical reductions, biological conversions, reforming and inorganic transformations. Furthermore, the vast research area of carbon capture and storage is reviewed briefly. This review is intended as an introduction to CO2, its synthetic reactions and their possible role in future CO2 mitigation schemes that has to match the scale of man-made CO2 in the atmosphere, which rapidly approaches 1 teraton.

The teraton challenge. A review of fixation and transformation of carbon dioxide

A new tris(ZnII−cyclen) (Zn3L3), which has three ZnII−macrocyclic tetraamine (cyclen) complexes connected through a 1,3,5-trimethylbenzene spacer, has been synthesized as a novel receptor for organ...

A Tris(ZnII−1,4,7,10-tetraazacyclododecane) Complex as a New Receptor for Phosphate Dianions in Aqueous Solution

On the basis of the chemical principle of carbonic anhydrase (CA)−aromatic sulfonamide inhibitor interaction, a dansylamidoethyl−pendant cyclen (1-(2-(5-(dimethylamino)-1-naphthalenesulfonamido)ethyl)-1,4,7,10-tetraazacyclododecane, HL) has been synthesized as a novel type of zinc(II)−fluorophore. The new ligand HL forms very stable complexes (ML) with zinc(II), cadmium(II), and copper(II) at physiological pH. The potentiometric and spectrophotometric pH-titration study disclosed the 1:1 metal(II) complexes stability constants log K(ML) (= log([ML]/[M][L])) to be 20.8 ± 0.1 for ZnL, 19.1 ± 0.1 for CdL, and >30 for CuL. The crystalline zinc(II) complex ZnL was isolated from aqueous solution at pH 7. The X-ray crystal study of ZnL disclosed a five-coordinate, distorted square-pyramidal structure with the deprotonated dansylamide N- coordinating at the apical site. Crystals of the monoperchlorate salt of ZnL (C22H35N6O6SClZn) are orthorhombic, space group Pna21 (no. 33) with a = 23.777(3) A, b = 12.744(5) A,...

A novel biomimetic zinc(ii)-fluorophore, dansylamidoethyl-pendant macrocyclic tetraamine 1,4,7,10-tetraazacyclododecane (cyclen)

Novel complementary associations have been found in a newly synthesized ternary Zn II complex of a macrocyclic tetraamine, [12]aneN 4 (=1,4,7,10-tetraazacyclododecane, cyclen, L), and N(3)-deprotonated AZT (=3'-arido-3'-deoxythymidine), 8. The X-ray crystal analysis of 8 revealed a distorted square-pyramidal N 5 -coordinate structure where a strong interaction occurs between Zn II and the N(3)-deprotonated anion of the pyrimidine ring (Zn II -LN(3)=2.053(8) A 8 )

A new ternary zinc(II) complex with [12]aneN4 (=1,4,7,10-tetraazacyclododecane) and AZT (=3'-azido-3'-deoxythymidine). Highly selective recognition of thymidine and its related nucleosides by a zinc(II) macrocyclic tetraamine complex with novel complementary associations

Model studies using Zn2+ complexes of various derivatives of macrocyclic triamines ([12]aneN3) and tetraamines (cyclen) have been found to be useful in elucidating and understanding the intrinsic p...

Model studies for molecular recognition of carbonic anhydrase and carboxypeptidase.

The catalytic carboxyester hydrolysis by a new zinc(II) complex with an alcohol-pendant cyclen (1-(2-hydroxyethyl)-1,4,7,10-tetraazacyclododecane): A novel model for indirect activation of the serine nucleophile by zinc(II) in zinc enzymes

Eiichi Kimura

Papers

A Tris(ZnII−1,4,7,10-tetraazacyclododecane) Complex as a New Receptor for Phosphate Dianions in Aqueous Solution

A novel biomimetic zinc(ii)-fluorophore, dansylamidoethyl-pendant macrocyclic tetraamine 1,4,7,10-tetraazacyclododecane (cyclen)

A new ternary zinc(II) complex with [12]aneN4 (=1,4,7,10-tetraazacyclododecane) and AZT (=3'-azido-3'-deoxythymidine). Highly selective recognition of thymidine and its related nucleosides by a zinc(II) macrocyclic tetraamine complex with novel complementary associations

Model studies for molecular recognition of carbonic anhydrase and carboxypeptidase.

The catalytic carboxyester hydrolysis by a new zinc(II) complex with an alcohol-pendant cyclen (1-(2-hydroxyethyl)-1,4,7,10-tetraazacyclododecane): A novel model for indirect activation of the serine nucleophile by zinc(II) in zinc enzymes