ABSTRACT
Three N-H functionalized metal-organic frameworks, Pb-DDQ, Zn-DDQ, and Cu-DDQ, were synthesized with a new flexible dicarboxylate ligand based on quinoxaline (H2DDQ = N,N'-dibenzoic acid-2,3-diaminoquinoxaline). CO2 adsorptions indicate that Zn-DDQ and Cu-DDQ have greatly enhanced the CO2 uptake due to the opposite N-H groups on pyrazine. With very small adsorption of N2, Cu-DDQ shows high selectivity for CO2 and N2. The three MOFs also have large adsorptions of some selected dyes, while Zn-DDQ and Cu-DDQ with large but different shapes of pores are demonstrated to be promising materials for fast separation of MB/other and CV/other mixtures, respectively. The cyanosilylation of aldehydes and ketones with high yields in a short reaction time for Cu-DDQ indicates that Cu-DDQ has a higher Lewis acidity than the other two MOFs.
ABSTRACT
The title compound, C(7)H(11)NO(7)P(2), exists as a zwitterion in which the positive charge resides on the protonated pyridyl N atom and the negative charge on one of the two phosphate groups. In the crystal, adjacent molcules are linked by O-Hâ¯O and N-Hâ¯O hydrogen bonds into a three-dimensional network.
ABSTRACT
In the title compound, [Cu(NO(3))(C(10)H(8)N(2))(2)]ClO(4), the five-coordinated Cu(II) atom has a distorted square-pyramidal CuN(4)O environment; the O atom is in the axial position whereas the N atoms from two bipyridine (bipy) ligands are in the equatorial plane. In the crystal, mol-ecules are assembled by C-Hâ¯O hydrogen bonding and π-π inter-actions between bipy groups [centroid-centroid distances = 3.7686â (16) and 3.7002â (16)â Å] into a three-dimensional network. The nitrite anion is equally disordered over two sets of sites.
ABSTRACT
The oxidation of adenine in phosphate buffer solution is investigated using square-wave voltammetry and in situ UV spectroelectrochemistry. The geometry of adenine and the derivatives optimized at DFTB3LYP-6-31G (d, p)-PCM level is in agreement with the crystal structure, and the imitated UV spectra of adenine and the product at electrode are consistent with the in situ UV spectra. The relationship between the electrochemical property and the molecular structure is also discussed. The experimental and theoretical results show that the adenine oxidation origins from the neutral adenine.
Subject(s)
Adenine/chemistry , Electrochemical Techniques , Phosphates/chemistry , Spectrophotometry, Ultraviolet , Buffers , Normal Distribution , Oxidation-ReductionABSTRACT
A novel (3,4-disfluoro)phenylquione (2F-PQ) was synthesized through the reaction of 3,4-Difluoroaniline and 1,4-benzoquinone. Its structure was verified by (1)H NMR, FTIR and Raman spectra. The ground-state geometries were optimized by using density functional theory (DFT) at B3LYP/6-311G+(d,p), B3PW91/6-311G+(d,p) and MPB3PW91/6-311G+(d,p) level without symmetry constrains, respectively. The predicted FTIR and Raman spectra scaled by factor are well consistent with experimental spectra.
Subject(s)
Benzoquinones/chemical synthesis , Vibration , Benzoquinones/chemistry , Models, Molecular , Molecular Conformation , Spectrophotometry, Infrared , Spectrum Analysis, RamanABSTRACT
In the title compound, (C(8)H(20)N)[Mn(C(22)H(18)N(2)O(4))(H(2)O)(2)][Fe(CN)(6)]·2CH(3)OH·2C(2)H(5)OH or [NEt(4)][Mn(3-Meosalophen)(H(2)O)(2)](2)[Fe(CN)(6)]·2CH(3)OH·2C(2)H(5)OH, the asymmetric unit consists of one half of an [NEt(4)](+) cation disordered around a twofold axis, the [Mn(3-Meosalophen)(H(2)O)(2)](+) coordination cation, one half of a C(2) symmetric [Fe(CN)(6)](3-) anion and disordered methanol and ethanol solvent mol-ecules that are equally populated at two different sites. The Mn(III) atom chelated by the 3-Meosalophen ligand adopts a slightly distorted MnN(2)O(4) octa-hedral geometry with the coordination completed by two water mol-ecules. The [Mn(3-Meosalophen)(H(2)O)(2)](+) cations, [Fe(CN)(6)](3- )anions and solvent mol-ecules are connected into a zigzag chain through hydrogen-bonding inter-actions.
ABSTRACT
The nanometer-sized materials have attracted much interest of analysts in recent years because of their special physicschemistry characteristics. As the scale decreases to nanometer grade, the number of atoms on the surface increases remarkably, resulting in the unsaturation. This makes the nanometer-sized materials have a high adsorptivity for the metal atoms. In the present paper, the nanometer-sized TiO2 was applied in the separation and preconcentration of Cr(III) and Cr(VI) in water. The influence of pH on the adsorption of Cr(III) and Cr(VI) was studied. When pH is larger than 6, 90%, Cr(III) is adsorbed onto the nanometer-sized material surface, while is basically not adsorbed in aqueous solution. Therefore, the separation of Cr(III) and Cr(VI) is achieved. At the pH of 6.5, Cr(III) was adsorbed by nanometer-sized TiO2 and desorbed with 2.0 mol x L(-1) HCl, in which the Cr(III) could be preconcentrated. The Cr(III) solution, as well as the Cr(VI) aqueous solution was determined by FAAS. The detection limits of Cr(M) and Cr(VI) were 41 and 57 ng x mL(-1), respectively. And the linear ranges for Cr(III) and Cr(VI) were 0-9.0 microg x mL(-1) and 0.1-10 microg x mL(-1) with a RSDs of 2.6% and 3.4% (n=6, c = 2.0 microg x mL(-1), respectively. This method was applied in the simultaneous determination of Cr(III) and Cr(VI) in the industrial wastewater and river water, and the satisfactory recovery results were obtained.
ABSTRACT
In the title compound, [Cu(C(10)H(10)NO(3))(C(5)H(8)N(2))(2)]·2H(2)O, the Cu(II) atom is coordinated by three N atoms and two O atoms in a distorted square-pyramidal geometry. The crystal packing is stabilized by inter-molecular O-Hâ¯O and N-Hâ¯O hydrogen bonds.
