[Sc©[3]CPP]+: A Viable Metal-Centered [3]Cycloparaphenylene.

[n]Cycloparaphenylenes ([n]CPPs, n denotes the number of phenyl groups) are difficult to synthesize because of the strain related to their bent phenyl rings. In particular, the strain in [3]CPP is high enough to destroy the π electron delocalization, leading to the spontaneous structural transition to an energetically more stable "bond-shift" (BS) isomer ([3]BS). In this contribution, we propose to achieve [3]CPP by enhancing the π electron delocalization through hosting a guest metal atom. Our computations revealed that Sc could stabilize [3]CPP by forming the [Sc©[3]CPP]+ complex through the favorable π-Sc donation-backdonation interactions. Thermodynamically, the binding energy between the Sc atom and [3]CPP was -205.7 kcal/mol, which could well compensate not only the energy difference of 44.2 kcal/mol between [3]CPP and [3]BS but also the extremely high strain energy of 170.3 kcal/mol in [3]CPP. Simultaneously, the [Sc©[3]CPP]+ complex is stable up to 1500 K in dynamic simulations, suggesting its high viability in the synthesis.

Syntheses, structures and magnetic properties of two CoII/NiII isostructural coordination polymers based on an asymmetric semirigid tricarboxylate ligand.

Two new isostructural complexes, namely, poly[aqua[µ3-2-(4-carboxyphenoxy)terephthalato-κ3O1:O4:O4'](1,10-phenanthroline-κ2N,N')cobalt(II)], [Co(C15H8O7)(C12H8N2)(H2O)]n or [Co(µ3-Hcpota)(phen)(H2O)]n, I, and poly[aqua[µ3-2-(4-carboxyphenoxy)terephthalato-κ3O1:O4:O4'](1,10-phenanthroline-κ2N,N')nickel(II)], [Ni(C15H8O7)(C12H8N2)(H2O)]n or [Ni(µ3-Hcpota)(phen)(H2O)]n, II, have been synthesized by solvothermal reactions. Complexes I and II were fully characterized by IR spectroscopy, elemental analyses, thermogravimetric analyses, and powder and single-crystal X-ray diffraction. They both present two-dimensional structures based on [M2(µ-COO)2]2+ (M = CoII or NiII) dinuclear metal units with a fes topology and a vertex symbol (4·82). Interestingly, the positions of the two dimeric metal motifs and the two partially deprotonated Hcpota2- ligands reproduce regular flying butterfly arrangements flipped upside down and sharing wings in the ab plane. Magnetic studies indicate antiferromagnetic interactions (J = -5.21 cm-1 for I and -11.53 cm-1 for II) in the dimeric units, with Co...Co and Ni...Ni distances of 4.397 (1) and 4.358 (1) Å, respectively, that are related to double syn-anti carboxylate bridges.

Nitrogen versus carbon in planar pentacoordinate environments supported by Be5H n rings.

NBe5H n n-3 (n = 0-5) (0A-5A) species with a novel planar pentacoordinate nitrogen (ppN) were designed by the isoelectronic substitution of the C atom in planar pentacoordinate carbon (ppC) species CBe5H n n-4 (n = 0-5) with an N atom. The highly flexible H atoms found in ppC species CBe5H2 2- and CBe5H3 - were fixed upon the nitrogen substitution, as mirrored by the non-flexible H atoms in their ppN analogues NBe5H2 - (2A) and NBe5H3 (3A). Moreover, the N atom was found to fit the H-surrounded Be5 rings better than the C atom because the ppC species CBe5H4 and CBe5H5 + adopted non-planar structures due to size-mismatch between the C atom and the H-surrounded Be5 ring, but their ppN analogues NBe5H4 + (4A) and NBe5H5 2+ (5A) adopted perfect planar structures. The electronic structure analyses revealed that the N atoms in 0A-5A were involved in four doubly occupied orbitals, including three six-center two-electron (6c-2e) σ bonds and one 6c-2e π bond. Therefore, these ppN species not only obey the octet rule, but also possess the interesting σ and π double aromaticity, which contributes to the stabilization. Consequently, 2A, 4A, and 5A are charged kinetically viable global energy minima, and are suitable for the gas phase generation and spectroscopic characterization.

Two CoII coordination polymers of biphenyl-2,2',5,5'-tetracarboxylic acid with flexible N-donor ligands: syntheses, structures and magnetic properties.

Two CoII-based coordination polymers, namely poly[(µ4-biphenyl-2,2',5,5'-tetracarboxylato){µ2-1,3-bis[(1H-imidazol-1-yl)methyl]benzene}dicobalt(II)], [Co2(C16H6O8)(C14H14N4)2]n or [Co2(o,m-bpta)(1,3-bimb)2]n (I), and poly[[aqua(µ4-biphenyl-2,2',5,5'-tetracarboxylato){1,4-bis[(1H-imidazol-1-yl)methyl]benzene}dicobalt(II)] dihydrate], {[Co2(C16H6O8)(C14H14N4)2(H2O)2]·4H2O}n or {[Co2(o,m-bpta)(1,4-bimb)2(H2O)2]·4H2O}n (II), were synthesized from a mixture of biphenyl-2,2',5,5'-tetracarboxylic acid, i.e. [H4(o,m-bpta)], CoCl2·6H2O and N-donor ligands under solvothermal conditions. The complexes were characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction and powder X-ray diffraction analysis. The bridging (o,m-bpta)4- ligands combine with CoII ions in different µ4-coordination modes, leading to the formation of one-dimensional chains. The central CoII atoms display tetrahedral [CoN2O2] and octahedral [CoN2O4] geometries in I and II, respectively. The bis[(1H-imidazol-1-yl)methyl]benzene (bimb) ligands adopt trans or cis conformations to connect CoII ions, thus forming two three-dimensional (3D) networks. Complex I shows a (2,4)-connected 3D network with left- and right-handed helical chains constructed by (o,m-bpta)4- ligands. Complex II is a (4,4)-connected 3D novel network with ribbon-like chains formed by (o,m-bpta)4- linkers. Magnetic studies indicate an orbital contribution to the magnetic moment of I and II due to the longer Co...Co distances. An attempt has been made to fit the χMT results to the magnetic formulae for mononuclear CoII complexes, the fitting indicating the presence of weak antiferromagnetic interactions between the CoII ions.

Synthesis, structure and selective luminescence sensing for iron(III) ions of a three-dimensional zinc(II) (4,6)-connected coordination network.

Coordination polymers constructed from conjugated organic ligands and metal ions with a d10 electronic configuration exhibit intriguing properties for chemical sensing and photochemistry. A ZnII-based coordination polymer, namely poly[aqua(µ6-biphenyl-3,3',5,5'-tetracarboxylato)(µ2-4,4'-bipyridine)dizinc(II)], [Zn2(C16H6O8)(C10H8N2)(H2O)2]n or [Zn2(m,m-bpta)(4,4'-bipy)(H2O)2]n, was synthesized from a mixture of biphenyl-3,3',5,5'-tetracarboxylic acid [H4(m,m-bpta)], 4,4'-bipyridine (4,4'-bipy) and Zn(NO3)2·6H2O under solvothermal conditions. The title complex has been structurally characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction and powder X-ray diffraction analysis, and features a µ6-coordination mode. The ZnII ions adopt square-pyramidal geometries and are bridged by two syn-syn carboxylate groups to form [Zn2(COO)2] secondary buildding units (SBUs). The SBUs are crosslinked by (m,m-bpta)4- ligands to produce a two-dimensional grid-like layer that exhibits a stair-like structure along the a axis. Adjacent layers are linked by 4,4'-bipy ligands to form a three-dimensional network with a {44.610.8}{44.62} topology. In the solid state, the complex displays a strong photoluminescence and an excellent solvent stability. In addition, the luminescence sensing results indicate a highly selective and sensitive sensing for Fe3+ ions.

[Effect of four line tension relaxing for nasal deviation rectification under endoscope].

OBJECTIVE: To explore the effect of four line tension relaxing septorhinoplasty for nasal deviation complicated with the deformity of nasal septal cartilage under endoscope. METHODS: Seventeen patients with nasal septum deviation from December 2009 to April 2011 were included in this study. The patients were divided into different groups depending on different deformity of quadrangular cartilage. Different surgical methods were used according to different deviation of nasal septum. First, a C-shape or L-shape incision was made on one side of the nasal septum under endoscope, then the nasal septal cartilage was separated from the angle formed by two greater alar cartilages, perpendicular plate of the ethmoid bone, the junction of vomer and maxilla at the nasal crest, and the upper lateral cartilage, this procedure was applied to correct deviation of nasal septum and nasal pyramid by decompression, which was named four lines tension relaxing correction. RESULTS: Seventeen patients with nasal septal deviation obtained satisfied curative effect. Nasal deviation and deviation of nasal septum were all corrected, patients got better appearance and good nasal ventilation, no complication was observed. CONCLUSION: Nasal deviation complicated with the deformity of nasal septal cartilage could be completely corrected by only one septorhinoplasty operation--four lines tension relaxing correction.

[Correlation study between obstructive level diagnosed by Apnea Graph and cephalometric posterior airway space in obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To study the correlation between Apnea Graph (AG) analysis of airway obstruction and cephalometric assessment of the posterior airway space in the diagnosis of obstructive level in patients with obstructive sleep apnea hypopnea syndrome (OSAHS), so as to improve the preoperative diagnostic accuracy and the therapeutic outcome. METHODS: Thirty patients (28 males and two females) who were diagnosed with severe OSAHS (mean AHI 58.6) by overnight polysomnography in recent 3 months were enrolled. The ages of the patients ranged from 35 to 59 years old with the median age of 41.5 years old. The mean body mass index (BMI, x(-) ± s) was (28.8 ± 4.1) kg/m(2). Mean apnea-hypopnea index (AHI) was (58.6 ± 16.4)/h. The lowest oxygen saturation was averaged to 0.69 ± 0.09. All patients underwent AG study as well as cephalometric analysis preoperatively. A correlation analysis was performed between the percentage of lower level obstructions measured by AG and the posterior airway space (PAS) evaluated by cephalometric analysis. RESULTS: All of the 30 patients had the obvious narrow PAS of 4.4 - 10.8 mm, with the average of (7.6 ± 2.1) mm. Their constituent ratios of lower level obstruction ranged from 2 to 87 percent with the median ratio of 15.5% [9.0%; 35.8%]. Among all the patients, only 2 cases had more than 50 percent obstruction of the airway at lower level, 8 cases had 30 to 40 percent obstruction, and 6 cases had the narrow PAS less than 6 mm. The constituent ratio of lower level obstructions had a negative rectilinear correlation with the data of PAS (r = -0.6511, P < 0.01), which meant the patient with a higher percentage of lower obstruction had the tendency to have a corresponding narrower PAS. Two cases whose constituent ratios of lower level obstructions were not compatible with the rectilinear tendency due to tonsillar hypertrophy were reported. CONCLUSIONS: AG analysis of airway obstruction and cephalometric assessment of the PAS could provide comparable and consistent results for the diagnosis of obstructive level in OSAHS. However, the tonsillar hypertrophy should be considered when using AG to identify the airway obstruction.

Synthesis, characterization, and studies on DNA binding of the complex Fe(Sal(2)dienNO(3).H(2)O).

A new metal complex, Fe(Sal(2)dienNO(3).H2O) (where Sal is salicylaldehyde and dien is diethylenetriamine), has been synthesized and characterized. The interactions between the Fe(III) complex and calf thymus DNA has been investigated using UV and fluorescence spectra, viscosity, thermal denaturation, and molecular modeling. The cleavage reaction on plasmid DNA has been monitored by agarose gel electrophoresis. The experimental results show that the mode of binding of the complex to DNA is classical intercalation and the complex can cleave pBR322 DNA.

Synthesis, characterization, and studies on DNA binding of a new Mg(II) complex with N1,N8-bis(1-methyl-4-nitropyrrole-2-carbonyl)triethylenetetramine.

A new Mg(II) complex of MgL(NO3)2 (here L = N(1),N(8)-bis(1-methyl-4-nitropyrrole-2-carbonyl)triethylenetetramine) has been synthesized and characterized. The interactions between the Mg(II) complex and calf thymus DNA has been investigated using UV spectra, fluorescent spectra, viscosity, thermal denaturation, and molecular modeling. The cleavage reaction on plasmid DNA has been monitored by agarose gel electrophoresis. The experimental results show that the mode of binding of the complex to DNA is non-classical electrostatic action and the complex can cleave pBR322 DNA.

Synthesis, characterization and studies on DNA-binding of a new Cu(II) complex with N1,N8-bis(l-methyl-4-nitropyrrole-2-carbonyl)triethylenetetramine.

A new Cu(II) complex of CuLCl(2) (here, L=N(1),N(8)-bis(1-methyl-4-nitropyrrole-2- carbonyl)triethylenetetramine) had been synthesized and characterized. The structure of the complex was investigated with density functional theory (DFT) calculations. DNA-binding of the Cu(II) complex and its effects on tumor cell viability were firstly studied. The interactions between the complex and calf thymus DNA had been investigated using UV spectra, fluorescent spectra, viscosity and CV (cyclic voltammetry). The cleavage reaction on plasmid DNA has been monitored by agarose gel electrophoresis. The experimental results show that the mode of binding of the complex to DNA is classical intercalation and the complex can cleave pBR322 DNA. The effects of the CuL on cell viability were tested using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) dye assay and the results indicate that the CuL had certain effect on cancer cells.