N'-(3-Hy-droxy-benzyl-idene)-4-methyl-benzohydrazide.

The title compound, C(15)H(14)N(2)O(2), was obtained from the reaction of 3-hy-droxy-benzaldhyde and 4-methyl-benzo-hydrazide in methanol. In the mol-ecule, the benzene rings form a dihedral angle of 2.9 (3)°. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into layers parallel to (101). The crystal packing also exhibits π-π inter-actions between the aromatic rings [centroid-centroid distance = 3.686 (4) Å].

N'-(2-Hy-droxy-4-meth-oxy-benzyl-idene)-4-methyl-benzohydrazide.

The asymmetric unit of the title compound, C(16)H(16)N(2)O(3), contains four independent mol-ecules with different conformations; the dihedral angles between the two benzene rings in the mol-ecules are 39.7 (3), 45.4 (3), 50.6 (3) and 51.6 (3)°. Intramolecular O-H⋯N hydrogen bonds are observed in the molecule. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into two crystallographically independent chains propagating in [010], and each chain is formed by two alternating independent mol-ecules. Weak C-H⋯O inter-actions also occur.

2-[(5-Chloro-2-oxidobenzyl-idene)aza-nium-yl]-2-methyl-propane-1,3-diol.

The title compound, C(11)H(14)ClNO(3), was prepared by the condensation of equimolar quanti-ties of 5-chloro-salicyl-aldehyde and 2-amino-2-methyl-propane-1,3-diol in methanol. In the crystal, it exists in the zwitterionic form, with nominal proton transfer from the phenol group to the imine N atom. This results in the formation of an intra-molecular N-H⋯O hydrogen bond, which generates an S(6) ring. Inter-molecular O-H⋯O hydrogen bonds arise from the hy-droxy groups, forming (001) sheets.

(E)-N'-(4-Hy-droxy-benzyl-idene)-3-nitro-benzohydrazide.

The mol-ecule of the title compound, C(14)H(11)N(3)O(4), assumes an E conformation about the C=N double bond. The benzene rings form a dihedral angle of 3.9 (2)°. The crystal structure is stabilized by N-H⋯O, O-H⋯N, O-H⋯O and C-H⋯O hydrogen bonds, forming layers parallel to (101). In addition, intra-layer π-π stacking inter-actions [centroid-centroid distance = 3.635 (2) Å] are observed.

2-Fluoro-N'-[(2-hydroxynaphthalen-1-yl)methylidene]benzohydrazide.

In the title mol-ecule, C(18)H(13)FN(2)O(2), the hy-droxy group is involved in an intra-molecular O-H⋯N hydrogen bond. The naphthyl ring system and the benzene ring form a dihedral angle of 31.0 (2)°. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into chains propagating in [101].

2-Bromo-4-chloro-6-(cyclo-hexyl-imino-meth-yl)phenol.

The title compound, C(13)H(15)BrClNO, was prepared by the condensation of equimolar quanti-ties of 3-bromo-5-chloro-salicyl-aldehyde with cyclo-hexyl-amine in methanol. There is an intra-molecular O-H⋯N hydrogen bond in the mol-ecule. The cyclo-hexyl ring adopts a chair conformation.

N'-(5-Bromo-2-hy-droxy-benzyl-idene)-4-nitro-benzohydrazide methanol monosolvate.

In the title compound, C(14)H(10)BrN(3)O(4)·CH(4)O, the benzohydrazide mol-ecule is nearly planar [maximum deviation = 0.110 (2) Å]. The mean planes of the two benzene rings make a dihedral angle of 8.4 (3)°. In the benzohydrazide mol-ecule, there is an intra-molecular O-H⋯N hydrogen bond and the NH group is hydrogen bonded to the methanol solvent mol-ecule. In the crystal, inter-molecular O-H⋯O hydrogen bonds involving the methanol solvent mol-ecule link the benzohydrazide mol-ecules to form chains which propagate along the a axis.

N'-(3,5-Dibromo-2-hy-droxy-benzyl-idene)-4-nitro-benzohydrazide methanol monosolvate.

The title compound, C(14)H(9)Br(2)N(3)O(4)·CH(4)O, was obtained as the product of the reaction of 3,5-dibromo-salicyl-aldehyde with 4-nitro-benzohydrazide in methanol. The benzohydrazide mol-ecule is nearly planar, with a maximum deviation of 0.126 (2) Å. The mean planes of the two benzene rings make a dihedral angle of 9.3 (3)°. Intra-molecular O-H⋯N and O-H⋯Br inter-actions are observed in the benzohydrazide mol-ecule. In the crystal, pairs of adjacent benzohydrazide mol-ecules are linked by two methanol mol-ecules through inter-molecular O-H⋯O and N-H⋯O hydrogen bonds, forming a dimer.

N'-[(2-Methoxynaphthalen-1-yl)methyl-idene]-4-methyl-benzohydrazide.

In the title compound, C(20)H(18)N(2)O(2), the mean planes of the naphthyl system and the benzene ring form a dihedral angle of 88.48 (10)°. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into C(4) chains, which propagate along the b-axis direction.

Ultrasound-assisted emulsification-microextraction combined with flame atomic absorption spectrometry for determination of trace cadmium in water samples.

The process of ultrasound-assisted emulsification-microextraction (USAEME) was successfully applied for the first time for the extraction and pre-concentration of trace cadmium from water samples, followed by flame atomic absorption spectrometry (FAAS). In the proposed approach, sodium diethyldithiocarbamate trihydrate solution (NaDDTC.3H(2)O) was used as a chelating agent and carbon tetrachloride was selected as extraction solvent. Some effective parameters on the microextraction and the complex formation were selected and optimized. These parameters included extraction solvent type as well as extraction volume, time, temperature, and pH, the amount of the chelating agent, and salt effect. Under optimum conditions, an enrichment factor of 95 was obtained from only 5.0 mL of water sample. The calibration graph was linear in the range of 10-600 microg L(-1) with a detection limit of 0.91 microg L(-1). The relative standard deviation (R.S.D) for ten replicate measurements of 50 and 500 microg L(-1) of cadmium were 2.56 and 1.62%. This proposed method was successfully applied in the analysis of four real environmental water samples and good spiked recoveries over the range of 96.5-101.7% were obtained.

[Study on the interaction of luteolin with human serum albumin by fluorescence quenching method].

The interaction between luteolin and human serum albumin (HSA) was studied by using fluorescence quenching spectra, synchronous fluorescence spectra and ultra-violet spectra. The results showed that luteolin had a strong ability to quench the fluorescence of HAS The Stern-Volmer curve of the fluorescence quenching of HSA by luteolin indicated that the mechanism behind the quenching between luteolin and HSA was a static quenching. According to the Forster theory of non-radiation energy transfer, the binding distances (r) and the binding constants (KA) were calculated. The thermodynamic parameters showed that the interaction between luteolin and HSA was driven mainly by hydrophobic force. Synchronous spectra were used to investigate the conformational changes of HSA.

Interaction of tetrandrine with human serum albumin: a fluorescence quenching study.

The interaction of tetrandrine with human serum albumin (HSA) was studied by measuring fluorescence quenching spectra, synchronous fluorescence spectra and ultra-violet spectra. The fluorescence quenching spectra of HSA in the presence of tetrandrine showed that tetrandrine quenched the fluorescence of HSA. The quenching constants of tetrandrine on HSA were determined using the Stern-Volmer equation. Static quenching and non-radiation energy transfer were the two main reasons leading to the fluorescence quenching of HSA by tetrandrine. According to the Förster theory of non-radiation energy transfer, the binding distances (r) and the binding constants (K(A)) were obtained. The thermodynamic parameters obtained in this study revealed that the interaction between tetrandrine and HSA was mainly driven by a hydrophobic force. The conformational changes of HSA were investigated by synchronous spectrum studies.

[Study on the interaction between fangchinoline and bovine serum albumin].

The binding reaction of fangchinoline with bovine serum albumin was studied at different temperatures by fluorescence quenching spectra, synchronous fluorescence spectra and ultra-violet spectra. It was shown that fangchinoline has a strong ability of quenching the fluorescence of BSA. The Stern-Volmer curve of the fluorescence quenching of BSA by fangchinoline indicated that the quenching mechanism of fangchinoline to BSA was a static quenching. According to the Förster theory of non-radiation energy transfer, the binding distances (r) at different temperature were 2.51 nm (27 degrees C), 2.72 nm (37 degrees C) and 2.89 nm (47 degrees C), respectively, while the binding constants (KA) were 1.05 x 10(5) L x mol(-1) (27 degrees C), 3.31x 10(5) L x mol(-1) (37 degrees C), and 7.24 x 10(5) L x mol(-1) (47 degrees C), respectively. The thermodynamic parameters showed that the interaction of fangchinoline and BSA was mainly driven by hydrophobic force. Synchronous spectrum was used to investigate the conformational changes of BSA.