ABSTRACT
Fluorescent porous organic cage with good water solubility is of great interest but still challenging for its fluorescent sensing application. Poor water solubility and single signal of most previous probes are unfavorable for the monitoring of Au3+ generated from the potential dissociation of gold nanoparticles in environmental and biological samples. Here we report a water-soluble porous organic cage as a ratiometric fluorescent probe for Au3+ in aqueous solution. The prepared porous organic cage with good water solubility showed specific redox interaction with Au3+ in pH 5, leading to the change of dual emission at 420 and 484 nm. Based on the change of fluorescence ratio, a simple ratiometric sensing method for Au3+ from the dissociation of gold nanoparticles in aqueous solution was developed. The proposed method gave a calibration function of F484/F420 = 0.0370[Au3+] + 0.5689 (where F484/F420 is the intensity ratio of fluorescence at 484 nm to that at 420 nm; [Au3+] in µM) (R2 = 0.9975) in the concentration range of 1-60 µM, the limit of detection (3s) of 8 nM, and the relative standard deviation of 0.26% for 10 replicate detections of 50 µM Au3+. The recoveries of spiked Au3+ in domestic wastewater and human serum samples ranged from 94.66% to 105.61%.
Subject(s)
Gold , Metal Nanoparticles , Humans , Porosity , Solubility , WaterABSTRACT
The title complex, [FeZn(C(5)H(5))Cl(2)(C(20)H(14)N(3))]·CH(3)CN, is composed of one Zn(II) atom, one 4'-ferrocenyl-2,2':6',2''-terpyridine (fctpy) ligand, two Cl atoms and one acetonitrile solvent mol-ecule. The Zn(II) atom is five-coordinated in a trigonal-bipyramidal geometry by the tridentate chelating fctpy ligand and two Cl atoms.
ABSTRACT
A new beta-cyclodextrin dimer, 2,6-dimethylpyridine-bridged-bis(6-monoammonio-beta-cyclodextrin) (pyridyl BisCD, L), is synthesized. Its zinc complex (ZnL) is prepared, characterized, and applied as a catalyst for diester hydrolysis. The formation constant (log K(ML)=7.31+/-0.04) of the complex and deprotonation constant (pK(a1)=8.14+/-0.03, pK(a2)=9.24+/-0.01) of the coordinated water molecule were determined by a potentiometric pH titration at (25+/-0.1) degrees C, indicating a tridentate N,N',N''-zinc coordination. Hydrolysis kinetics of carboxylic acid esters were determined with bis(4-nitrophenyl)carbonate (BNPC) and 4-nitrophenyl acetate (NA) as the substrates. The resulting hydrolysis rate constants show that ZnL has a very high rate of catalysis for BNPC hydrolysis, yielding an 8.98x10(3)-fold rate enhancement over uncatalyzed hydrolysis at pH 7.00, compared to only a 71.76-fold rate enhancement for NA hydrolysis. Hydrolysis kinetics of phosphate esters catalyzed by ZnL are also investigated using bis(4-nitrophenyl)phosphate (BNPP) and disodium 4-nitrophenyl phosphate (NPP) as the substrates. The initial first-order rate constant of catalytic hydrolysis for BNPP was 1.29x10(-7) s(-1) at pH 8.5, 35 degrees C and 0.1 mM catalyst concentration, about 1600-fold acceleration over uncatalyzed hydrolysis. The pH dependence of the BNPP cleavage in aqueous buffer was shown as a sigmoidal curve with an inflection point around pH 8.25, which is nearly identical to the pK(a) value of the catalyst from the potentiometric titration. The k(BNPP) of BNPP hydrolysis promoted by ZnL is found to be 1.68x10(-3) M(-1) s(-1), higher than that of NPP, and comparatively higher than those promoted by its other tridentate N,N',N''-zinc analogues.
Subject(s)
Organometallic Compounds/chemistry , Zinc/chemistry , beta-Cyclodextrins/chemistry , Catalysis , Dimerization , Esters , Hydrolysis , Hydrophobic and Hydrophilic Interactions , Kinetics , beta-Cyclodextrins/chemical synthesisABSTRACT
The title complex, [CuFe(C(5)H(5))(C(20)H(14)N(3))(C(12)H(8)N(2))](ClO(4))(2)·C(2)H(3)N, consists of a mononuclear [Cu(C(12)H(8)N(2))(C(25)H(19)FeN(3))](2+) cation, two ClO(4) (-) anions (one of which is disordered over two positions with equal occupancy) and one CH(3)CN solvent mol-ecule. The Cu(II) center has a distorted square-pyramidal coordination with three N atoms of the 4'-ferrocenyl-2,2':6',2''- terpyridine (fctpy) ligand and one 1,10-phenanthroline (phen) N atom in the basal plane and a second phen N atom in the apical position with an axial distance of 2.254â (4)â Å. The disordered ClO(4) (-) anion is weakly coordin-ated to the Cu(II) ion with a Cu-O distance of 2.766â (11)â Å. The two cyclo-penta-dienyl rings of the ferrocenyl group are almost eclipsed with a deviation of 4.7â (1) °, and are involved in inter-molecular π-π inter-actions with the outer pyridyl rings of the fctpy ligands [centroid-centroid distance = 3.759â (2)â Å.].
ABSTRACT
In the title complex, [FeZn(C(5)H(5))(C(20)H(14)N(3))(C(12)H(8)N(2))](ClO(4))(2)·CH(3)CN, the Zn(II) atom is five-coordinated by a tridentate chelating 4'-ferrocenyl-2,2':6',2''-terpyridine (fctpy) ligand and a bidentate chelating 1,10-phenanthroline (phen) ligand in a distorted square-pyramidal environment with a phen N atom located at the apical position [Zn-N = 2.259â (4)â Å]. The terpyridyl motif in each fctpy ligand is coplanar, but the cyclo-penta-dienyl ring is twisted by 9.5â (2)° out of coplanarity with each central pyridine. The two cyclo-penta-dienyl rings of the ferrocenyl group are almost eclipsed with a deviation of 4.5â (1)°. In addition, inter-molecular π-π inter-actions [centroid-centroid distance 3.753â (2)â Å] are present between the cyclo-penta-dienyl and outer pyridyl rings of the fctpy ligands. One of the perchlorate anions is equally disordered over two positions.
ABSTRACT
In the title compound, C(26)H(23)N, the complete molecule is generated by crystallographic mirror symmetry, with the N atom and four C atoms lying on the reflection plane. The dihedral angles between the pyridine ring and pendant benzene rings are 2.9â (1), 14.1â (1) and 14.1â (1)°. Neighbouring mol-ecules are stabilized through inter-molecular π-π inter-actions along the c axis [centroid-to-centroid distance = 3.804â (2)â Å], forming one-dimensional chains.
ABSTRACT
The title compound, C(19)H(14)O, contains two independent mol-ecules with the same s-cis conformation for the ketone unit. Both mol-ecules are non-planar with dihedral angles of 51.9â (1) and 48.0â (1)° between the benzene ring and the naphthalene ring system. In the crystal, neighboring mol-ecules are stabilized by intermolecular C-Hâ¯π inter-actions, giving a two-dimensional supra-molecular array parallel to the ab plane.
ABSTRACT
In the title compound, [Co(C(6)H(5)N(2)O(4))(2)(H(2)O)(2)]·2C(3)H(7)NO, the Co(II) ion lies on an inversion center and adopts a slightly distorted CoN(2)O(4) octa-hedral geometry binding two bidentate chelating 5-carb-oxy-2-methyl-1H-imidazole-4-carboxyl-ate (H(2)MIDA(-)) monoanionic ligands and two axial aqua ligands. In the crystal structure, inter-molecular O-Hâ¯O hydrogen bonds link neighboring mol-ecules, generating a two-dimensional framework containing eight-membered H(4)O(4) rings. In addition, the dimethyl-formamide solvent mol-ecules are hydrogen bonded to the two-dimensional framework via the NH groups of the H(2)MIDA(-) ligands.
ABSTRACT
The title compound, C(13)H(13)N(3), is non-planar, with the pyridine and phenyl rings inclined at an angle of 80.7â (3)°. The central ethyl-idenehydrazine atoms lie in a plane [mean deviation = 0.013â (1)â Å], which forms dihedral angles of 88.5â (1) and 9.4â (1)° with the pyridine and phenyl rings, respectively. In the crystal structure, mol-ecules are linked by inter-molecular N-Hâ¯N hydrogen bonds into infinite chains propagating along the b axis.
ABSTRACT
The molecule of the title compound, C(15)H(16)N(2)O, is non-planar with a dihedral angle of 16.0â (1)° between the pyrrole and benzene rings. The ketone double-bond displays an s-cis conformation with an O=C-C=C torsion angle of 7.9â (3) and an intramolecular C-Hâ¯O hydrogen bond. In the crystal structure, adjacent mol-ecules are paired through N-Hâ¯O hydrogen bonds into centrosymmetric dimers.
