Novel [2]catenane structures introducing communication between transition metal centers via pi...pi interactions

[2]Catenane systems containing copper(II) and nickel(II) as metal centers have been self-assembled using tetraazamacrocyclic complexes and benzo-24-crown-8 as building blocks. A variety of methods, including X-ray crystallography, ESI mass spectrometry, (13)C and (1)H NMR, and electrochemistry, were applied to characterize these new face-to-face bismacrocyclic systems. Weak pi...pi interactions introduced by interlocking transition metal complexes with benzocrown moieties were shown to increase the communication (cooperativity) of metal centers. Introduction of the benzocrown increases the stability of the mixed valence state of the macrocyclic complex, which is reflected in high values of conproportionation constants. Moreover, this effect was found to be stronger than that obtained by shortening the length of the spacer between the two tetraazamacrocyclic subunits in the parent bismacrocycles. The extent of communication is larger for the nickel catenane than for the copper one.     

Structural instability of vortices in Bose-Einstein condensates

In this paper we study a gaseous Bose-Einstein condensate and show the following: (i) A minimum value of the interaction is needed for the existence of stable persistent currents. (ii) Vorticity is not a fundamental invariant of the system, as there exists a conservative mechanism which can destroy a vortex and change its sign. (iii) This mechanism is suppressed by strong interactions.     

Bioastrophysical aspects of low energy ion irradiation of frozen anthracene containing water

The origin of life on Earth remains a fascinating mystery in spite of many theories existing on this subject. However, it seems that simple prebiotic molecules could play an essential role in the formation of more complex organisms. In our experiment, we synthesized a class of these molecules (quinones) bombarding frozen anthracene containing water with low energy hydrogen ions. This experiment roughly simulated the astrophysical conditions which one can find in the solar system. Thus, we can hypothesize that prebiotic molecules could be created by interaction of the solar wind with interplanetary dust grains. The delivery of these molecules to early Earth may have contributed to the generation of life on our planet.     

Micromachining bulk glass by use of femtosecond laser pulses with nanojoule energy

Using tightly focused femtosecond laser pulses of just 5 nJ, we produce optical breakdown and structural change in bulk transparent materials and demonstrate micromachining of transparent materials by use of unamplified lasers. We present measurements of the threshold for structural change in Corning 0211 glass as well as a study of the morphology of the structures produced by single and multiple laser pulses. At a high repetition rate, multiple pulses produce a structural change dominated by cumulative heating of the material by successive laser pulses. Using this cumulative heating effect, we write single-mode optical waveguides inside bulk glass, using only a laser oscillator.     

Vortex revivals with trapped light

We predict that vortex dipoles nested in light beams trapped in graded-index media can undergo closed Berry trajectories, yielding periodic vortex annihilations and revivals along the light-propagation direction. The vortex revivals from vortex-free wave fronts are mediated by Freund stationary point bundles that carry the necessary Poincaré-Hopf indices. Vortex spiraling and spontaneous generation of circular-edge dislocations are also found to occur.     

Syntheses and Structures of Lanthanide Complexes with Isonicotinate

1 INTRODUCTION In recent years, chemists have paid their attention to the design and construction of extended metal- organic framework solids with potential applications, such as catalysts, nonlinear optical devices, ion ex- change, adsorption, sensors etc.[1, 2]. As one kind of polydentate ligands, isonicotinic acid has been exte- nsively employed to synthesize transition metal coo- rdination polymers[3, 4] with one-[5～8], two-[9～12] and three- dimensional[13～21] extended frameworks b…     

Synthesis and Crystal Structure of a Dinuclear Cobalt(II) Complex [Co2(1H-benzimidazole)4(1,4-bdoa)2]

1 INTRODUCTION In the last decades, metal carboxylate complexes have become a particularly important subject in mo- dern coordination chemistry owing to their fascina- ting structural diversity and potential applications as functional materials[1～3]. The generation of supramo- lecular architectures relies on the combination of se- veral factors, such as the coordination geometry of metals, bonding of the ligands and reaction condi- tions[4, 5]. In relation to the ligands, the judicious c…     

Synthesis and Crystal Structure of 3-（ 2- Hydroxybenzly ）-4-（ 4- Hydro xybenzylideneamino ）-（1H） - 1,2,4- Triazole-5-Thione and Its Antibacterial Activities

1 INTRODUCTION 2. 1 Physical measurements Azole derivatives, such as pyrazole, imidazole, All solvent and chemicals were commercial rea- triazole(including benzotriazole), tetrazole and indole, gents and used without further purification. Ele- have extensive biological activities. They have be- mental analyses were performed on a PE 1700 CHN come the central focus of studies for agricultural che- auto elemental analyzer. IR spectra were recorded on micals, medicines, plant growth regul…     

Assignment of cis-Epoxides and Crystal Structure of cis-4-Nitro-N-（7-oxabicyclo[4.1.0]hept-2-yl）benzamide

1 INTRODUCTION The success of strategies for total synthesis con-tinues to depend on high levels of stereoselectivityobserved in substrate-directed diastereoselective re-actions[1]. In this context, one of the most widelyused processes is diastereoselective epoxidation ofcyclic alkenes with allylic O- and N-directing group,which is very useful in building stereodefined syn-thetic blocks[2, 3] .However, in some circumstances,the assignment of resulting epoxides is not straight-forward[4～8…     

Crystal and Molecular Structure of 4-Hydroxy-3-Methoxy-4-N-Methylstilbazonium Iodide C_(15) H_(16) NO_2 +·I~-CrystalandMolecularS

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