A comprehensive electronic structure description of a biscyanotetraazacobalt(III) macrocyclic complex

Molecular modeling and a detailed spectroscopic characterization of the macrocyclic complex [Co(meso)(CN)(2)](+) (meso = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) is herein presented. Structural, electronic and vibrational features are discussed and assignments were proposed on the basis of semi-empirical (molecular mechanics (MM+), ZINDO/S and PM3) quantum-mechanics calculations. The energy and the composition of the molecular orbitals of the complex were calculated and a quantitative diagram was constructed. The simulated UV-vis spectrum exhibited a reasonably good accordance with the experimental one and fully assignments of seven bands were made. An optimized configuration of the complex showed a strong cobalt-cyanide axial bond in agreement with the major contribution of the cyanide to the composition of the molecular orbitals in contrast to a discrete participation of the macrocyclic meso to the ground state of the complex.     

Aqua cadmium cyanide coordination polymer with nitronyl nitroxide radical

A new three-dimensional diamagnetic metal nitronyl nitroxide radical coordination polymer with an aqua cadmium cyanide framework Cd(NIT4py)(H₂O)Cd(CN)₄·H₂O 1, was synthesized. X-ray crystallography reveals that the structure consists of 3D aqua cadmium cyanide built up by octahedral Cd^II coordinating to NIT4py and tetrahedral Cd^II (CN)₄ units. Magnetic measurements show that the χ_mT values are nearly constant at higher temperature. The lower χ_mT values at lower temperature are related to intermolecular antiferromagnetic interactions of the radicals, which arise due to the hydrogen bonded network (T_N = 21 K).     

Rebirth of a dead Belousov-Zhabotinsky oscillator

Long time behaviors of the Belousov-Zhabotinsky (BZ) reaction are experimentally analyzed in a closed reactor. The amplitude of the oscillation is suddenly damped after about 10 h. After about 5-20 h, the dead oscillator is suddenly restored with nearly the same amplitude as before it stopped its oscillation for certain values of the concentrations of sodium bromate and malonic acid (MA). With the other domains of the concentrations, the oscillator simply damps and never restores its oscillation. The phase diagram of the different types of damping behaviors as a function of the concentrations is obtained.     

π Back-bonding of iron(II) complexes supported by tris(pyrid-2-ylmethyl)amine and its nitro-substituted derivatives

The electronic and geometric structures of a series of iron(II) complexes supported by tetradentate tris(pyrid-2-ylmethyl)amine-type ligands with different numbers of 4-nitropyridine groups, [(PyCH(2))(3-n)(4-NO(2)PyCH(2))(n)N] (n = 0-3), were examined by X-ray absorption fine-structure and variable-temperature (1)H NMR spectroscopies and theoretical calculations to reveal how the low-spin state is stabilized through π back-bonding interactions between iron(II) and 4-nitropyridine donor group(s).     

Design of main-chain polymers of chiral imidazolidinone for asymmetric organocatalysis application

Main-chain polymers of chiral imidazolidinone were successfully synthesized by reaction of chiral imidazolidinone dimers with disulfonic acid. Chiral imidazolidinones were incorporated into the main-chain of the polymer by ionic bonding. These polymers could be used as polymeric chiral organocatalysts for asymmetric Diels-Alder reactions.     

Structural basis for oxygen sensing and signal transduction of the heme-based sensor protein Aer2 from Pseudomonas aeruginosa

The crystal structure of a truncated Aer2, a signal transducer protein from Pseudomonas aeruginosa, consisting of the heme-containing PAS and di-HAMP domains revealed that a distal tryptophan residue (Trp283) plays an important role in stabilizing the heme-bound O(2) and intra-molecular signal transduction upon O(2) binding.     

Approaches to ultimate functional polymers: quantum functional and molecular engineering materials

Both quantum functional material (Ψ‐engineering material) and molecular engineering materials are of interest as ultimate functional materials. The former creates a novel property which is specific to the structure, and the latter gives he functional material of the smallest size. In this paper, some aspects to construct those materials with polymer having big varieties and flexible applications are described: 1. Conjugating polymer superlattice (conjugating polymer multilayers which is able to change wave length of emission light). 2. Porphyrin arrays connected with molecular wires (a proto‐type photo‐information housing‐in and reading out polymeric material). 3. Oligonucleotide shackled with porphyrin (an artificial restrictive photoactive enzyme).