Divalent copper coordination polymers containing an isophthalate ligand and a dipyridylamide ligand show different dimensionalities and topologies depending on pyridyl nitrogen donor disposition and the steric bulk of the substituent on the dicarboxylate aromatic ring. According to single‐crystal X‐ray diffraction, [Cu(ip)(3‐pna)]n ( 1 , ip = isophthalate, 3‐pna = 3‐pyridylnicotinamide) shows a (4, 4) layered grid structure based on {Cu2(OCO)2} dimeric units. {[Cu(ip)(3‐pina)]·H2O}n ( 2 , 3‐pina = 3‐pyridylisonicotinamide) exhibits similar dimeric units, but in contrast to 1 these are connected into a non‐interpenetrated 3D 658 cds network. Both [Cu(mip)(3‐pina)]n ( 3 , mip = 5‐methylisophthalate) and [Cu(meoip)(3‐pina)]n ( 4 , mip = 5‐methoxyisophthalate) display dimer‐based 41263 pcu networks in contrast to 2 . Use of 5‐hydroxyisophthalate (H2hip) as a precursor afforded a mixture of {[Cu2(hip)2(3‐pina)4]·9.5H2O}n ( 5 ) and [Cu(hip)(3‐pina)]n ( 6 ). Compound 5 shows a 2D interdigitated structure with [Cu(hip)]n coordination polymer layers featuring {Cu2(OCO)2} dimeric units and pendant 3‐pina ligands, while 6 also showed a dimer‐based 41263 pcu network. Use of the very sterically bulky 5‐tert‐butylisophthalate (tbip) ligand afforded the 1D chain coordination polymer {[Cu(tbip)(3‐pina)2(H2O)]·H2O}n ( 7 ), which contains isolated copper ions in contrast to 1 – 6 , and has a curious “butterfly“ resemblance. Very weak antiferromagnetic coupling is seen within the {Cu2(OCO)2} dimeric units in 1 . Thermal decomposition behavior is also discussed. 相似文献
The flavoenzyme monoamine oxidase (MAO) regulates mammalian behavioral patterns by modulating neurotransmitters such as adrenaline and serotonin. The mechanistic basis which underpins this enzyme is far from agreed upon. Reported herein is that the combination of a synthetic flavin and alloxan generates a catalyst system which facilitates biomimetic amine oxidation. Mechanistic and electron paramagnetic (EPR) spectroscopic data supports the conclusion that the reaction proceeds through a radical manifold. This data provides the first example of a biorelevant synthetic model for monoamine oxidase B activity. 相似文献
A challenge for the design of scaffolds in tissue engineering is to determine a terminal sterilization method that will retain the structural and biochemical properties of the materials. Since commonly used heat and ionizing energy‐based sterilization methods have been shown to alter the material properties of protein‐based scaffolds, the effects of ethanol and ethylene oxide (EtO) sterilization on the cellular compatibility and the structural, chemical, and mechanical properties of uncrosslinked, UV crosslinked, or 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide (EDC) crosslinked fibrin microthreads in neutral (EDCn) or acidic (EDCa) buffers are evaluated. EtO sterilization significantly reduces the tensile strength of uncrosslinked microthreads. Surface chemistry analyses show that EtO sterilization induces alkylation of EDCa microthreads leading to a significant reduction in myoblast attachment. The material properties of EDCn microthreads do not appear to be affected by the sterilization method. These results significantly enhance the understanding of how sterilization or crosslinking techniques affect the material properties of protein scaffolds.
The synthesis, structure and properties of a 2D FeIII network material of composition [Fe(O-bipy)2Cl](TCNQ)2 (O-bipy = 4,4'-bipyridyl N,N'-dioxide; TCNQ = 7,7,8,8-tetracyanoquinodimethane) are presented. The structure consists of a square grid in which square pyramidal FeIII centers are linked to four equivalent centers through O-bipy ligands. Pairs of TCNQ radical anions are located within rectangular cavities of the 2D network. The apical position on each Fe center is occupied by a chloride ion. Magnetic studies are indicative of weak antiferromagnetic coupling. Electrical conductivity measurements reveal that the compound is a semiconductor and on the basis of DFT calculations it is proposed that electrical conduction occurs via charge hopping between interlayer TCNQ anions. Mössbauer spectra indicate a rare example of the Goldanskii–Karyagin effect and are suggestive of unusual dynamic processes. 相似文献
