Synthesis and Structure of the Acylhydrazone Schiff Base

Salicylaldehyde-2-（4-isobutylphenyl）-propionyl hydrazone Schiff base（H2L） has been synthesized and characterized by elemental analysis,IR,1H-NMR spectrum and single-crystal X-ray diffraction.Single-crystal X-ray diffraction analysis showed that H2L is of monoclinic system,space group P21/c with a = 5.6844（5）,b = 33.568（3）,c = 9.6959（9） ,β = 91.758（2）°,V = 1849.2（3） 3,Mr = 324.41,F（000） = 696,Z = 4,Dc = 1.165 g/cm3,μ = 0.076 mm-1,R = 0.0448 and wR = 0.1221.In the solid form,the strong intramolecular hydrogen bonds make H2L fully extended into an E isomer about the N=N bond,and each molecule interacts with two neighbors to form 1D hydrogen-bonded chains.The Schiff base presents two different sets of signals in the 1H-NMR and 13C-NMR spectra in either chloroform or dimethylsulfoxide solution,showing the presence of both E and Z isomers.

Crystal Structures,Thermal Behaviors and Biological Activities of Acylhydrazone Compounds Containing Pyrazine Rings and Halogen Atoms

Three new kinds of acylhydrazone compounds （C12H10FN5O？H2O, 1; C12H10ClN5O？2CH3COOH, 2; C12H10BrN5O, 3） were synthesized by the reaction of 2-amino-3- pyrazinecarbohydrazide （C5H7N5O） with halogenated benzaldehyde （C7H5OX, X = F, Cl, Br）. The structures of the three compounds were characterized by elemental analysis, 1H NMR, IR and X-ray diffraction. X-ray single-crystal diffraction presents that the three compounds all belong to triclinic system, P space group. Thermal gravity analyses show that three compounds have excellent thermal stabilities and all the thermal decomposition temperature of maximum weight loss was around 300 °C. The interactions of the compounds with CT-DNA were investigated by UV-Vis spectrum, fluorescence spectrum and viscosity measurement. All the results suggest that three compounds could bind with CT-DNA through intercalation. The fluorescence spectrum was also used to study the interactions of three compounds with BSA. It was proved that all the compounds could quench the intrinsic fluorescence of BSA via a static quenching process. Compound 2 displays the strongest binding ability both in the reaction with CT-DNA or BSA. Antimicrobial test was carried on Escherichia coli, Staphylococcus aureus and Salmonella, and 2 is more effective against S. aureus. But in MTT assay, 1 shows better cytotoxity activity against A549 cells.

Some Ferrocene Derivatives of Acylhydrazones

The title organometallic compounds were synthesized by the condensation of formyl and acetyl ferrocene with cyanoacetyl, propionyl, butyryl, o furoyl, o thiofuroyl and m pyridinecarboxy hydrazine in anhydrous ethanol under reflux. The IR, 1H NMR, MS, and Mssbauer spectra for these compounds were recorded and are discussed.

A simple strategy for constructing acylhydrazone photochromic system with visible color/emission change and its application in photo-patterning

As a potential photochromic system,acylhydrazones exhibit many outstanding adva ntages including low cost,simple synthesis and high modifiability compared with some classic photochromic systems.However,the absorption wavelengths of acylhydrazones usually locate in ultraviolet regio n,which makes the band separation between the absorbance maxima of its irradiated and unirradiated forms cannot be observed by naked eyes and greatly limits their practical applications.In this work,a simple strategy for constructing acylhydrazone photochromic system with visible color/emission change is provided.Rhodamine 6 G hydrazine-2-aldehyde-pyridine Schiff base(compound 3)is designed and synthesized by combining acylhydrazone with Rhodamine 6 G structure.The introduction of Rhodamine 6 G moiety to 3 not only makes it remain all the advantages of acylhydrazone photochromic system but also exhibits visible photo-induced color/emission changes both in solution and in a solid matrix.Moreover,3 exhibits reversible photochromic property with good fatigue re sistance,which makes it an excellent candidate for p hoto-patterning.

Synthesis, Crystal Structures, and Binding Behaviors with CT-DNA/BSA, Antimicrobial and Cytotoxic Activities of Three New Pyrazine Acylhydrazones

Three new acylhydrazones containing pyrazine ring(C12H11N5O2·CH3COOH,1;C13H13N5O·2CH3COOH,2;C13H13N5O3·C13H13N5O3,3)were synthesized and fully characterized.The single-crystal XRD indicated that both 1 and 2 crystallized in monoclinic,P21/c space group but 3 belonged to monoclinic,C2/c space group.The temperature of the maximum thermal decomposition peaks measured by thermogravimetry for 1~3 is 284,289 and 276℃respectively,all showing better thermal stabilities.The interactions of 1~3 with calf thymus DNA(CT-DNA)and bovine serum albumin(BSA)were studied by UV-Vis absorption spectroscopy and fluorescence spectroscopy,respectively,presenting that 1~3 could bind to CT-DNA via groove binding mode and quench the fluorescence of BSA through static process.Moreover,molecular docking studies of the interactions between 1~3 with DNA/BSA were in good agreement with experimental results.From antimicrobial activities of 1~3 and gentamycin sulfate against Staphylococcus aureus,Escherichia coli and Salmonella typhimurium,it was inferred that 3 had generally stronger antibacterial activity than 1 and 2 and is more active against Staphylococcus aureus than gentamycin sulfate.The cytotoxic tests of 1~3 and etoposide on human lung cancer cells(A549)were carried out by using the MTT method.

pH-sensitive Nanoparticles for High Loading and Efficient Delivery of Doxorubicin

An acid-sensitive delivery system based on acylhydrazone bond was developed for high loading and efficient delivery of doxorubicin.Doxorubicin(DOX)was covalently combined with dihydrazide adipate to form acid-sensitive hydrazone bond based on Schiff base reaction,then the intermediate was covalently combined with carboxymethyl chitosan through amide bond to form polymeric prodrugs,and nanoparticles were formed through self-assembling.Moreover,the structural and particle properties of CMCS-ADH-DOX were characterized by ultraviolet visible near infrared spectrophotometry(UV),nuclear magnetic resonance spectroscopy(^(1)H-NMR),fourier transform infrared spectroscopy(FT-IR),dynamic light scattering(DLS),and transmission electron microscopy(TEM).The mean diameter of the self-assembled nanoparticles is 165 nm,while the morphology is a relatively uniform spherical shape.Moreover,these DOXloaded nanoparticles showed pH-triggered drug release behavior.Compared with free DOX,CAD NPs showed lower toxic side effects in L929 cells and similar toxicity in 4T1 cells.The experimental results indicate that the CMCS-ADH-DOX nanoparticles may be used as an acid-sensitive targeted delivery system with good application prospect for cancer.

Synthesis and Crystal Structure of Isonicotinic Acid [1-(3,5-Dibromo-2- hydroxyphenyl)methylidene]hydrazide Methanol

A new Schiff base compound, C13H9Br2N3O2CH3OH, isonicotinic acid [1-（3,5- dibromo-2-hydroxyphenyl）methylidene]hydrazide methanol, has been synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. The compound comprises a Schiff base moiety isonicotinic acid [1-（3,5-dibromo-2-hydroxyphenyl） methylidene]hydrazide and a methanol molecule. The crystal belongs to the triclinic system, space group P1 with a = 8.464（1）, b = 9.511（2）, c = 10.901（2）A, a = 92.940（2）, β = 110.456（2）, y = 96.040（2）°, Z= 2, V= 814.0（2）A^3, Dc = 1.759 g/cm^3, Mr = 431.09, λ（MoKa） = 0.71073A, μ = 4.994 mm^-1, F（000） = 424, R = 0.0440 and wR = 0.1061. A total of 3284 unique reflections were collected, of which 2197 with I 〉 20（I） were observed. The molecule adopts a trans configuration about the C=N double bond. The dihedral angle between the benzene and pyridine rings is 22.0（4）°. The crystal structure is stabilized by intermolecular O-H…N and C-H…O hydrogen bonds, forming layers parallel to the ac plane. The preliminary biological tests show that the compound has potential antibacterial activities.

Synthesis and Crystal Structure of 2-Hydroxybenzoic Acid [1-(3,5-Dibromo-2-hydroxyphenyl)methylidene]hydrazide Methanol

A new Schiff base compound, 2-hydroxybenzoic acid [1-（3,5-dibromo-2-hydroxyphenyl） methylidene]hydrazide methanol （C14H10Br2N2O3·CH3OH）, has been synthesized by the condensation of equimolar 3,5-dibromosalicylaldehyde and 2-hydroxybenzoic acid hydrazide in a methanol solution. The compound was characterized by elemental analysis, IR spectra, and singlecrystal X-ray diffraction. The compound consists of a Schiff base moiety 2-hydroxybenzoic acid [1-（3,5-dibromo-2-hydroxyphenyl）methylidene]hydrazide and a lattice methanol molecule. The crystal belongs to the monoclinic system, space group P21/n with a = 7.183（1）, b = 15.673（2）, c = 15.001（2） A, β = 98.345（2）°, Z = 4, V = 1670.9（4） A^3, Dc = 1.773 g/cm^3, Mr = 446.10, λ（MoKα） = 0.71073 , μ = 4.872 mm^-1, F（000） = 880, R = 0.0458 and wR = 0.0963. A total of 3445 unique reflections were collected, of which 2236 with I 〉 2σ（Ⅰ） were observed. As expected, the molecule adopts a trans configuration about the C=N double bond. The two benzene rings are nearly coplanar （mean deviation from the combined plane is 0.061（4） ）, with the dihedral angle of 7.9（3）°. The preliminary biological tests show that the compound has moderate antibacterial activities.

Syntheses and Crystal Structures of Hg(Ⅱ)and Ag(Ⅰ)Complexes Containing 2-Acetylpyridine-paminobenzoylhydrazone Ligand

The two complexes [HgI_2L]（DMF）（1） and [AgL_2]（ClO_4）（CH_3CN）（2） were synthesized from the reaction of Schiff base ligand（2-acetylpyridine-p-aminobenzoylhydrazone）（L） with HgI_2 or AgClO_4 respectively. The compounds are characterized by ^1H NMR,FTIR and elemental analysis. The structures of the ligand and two complexes are measured via single-crystal X-ray diffraction. In these two complexes,the structures are both distorted triangular bipyramids with five-coordinated centers.

Crystal Structures, ct-DNA/BSA Binding Properties and Antibacterial Activities of Halogenated Pyridyl Hydrazones

Three new halogenated pyridyl hydrazones, namely 4-chlorobenzaldehyde-4-chloropyridine-2-formyl acylhydrazone(C(13)H9Cl2N3O, 3 a), 4-bromobenzaldehyde-4-chloropyridine-2-formyl acylhydrazone(C(13)H9BrClN3O, 3 b) and 4-iodobenzaldehyde-4-chloropyridine-2-formyl acylhydrazone(C(13)H9ClIN3O, 3 c), have been synthesized and characterized by elemental analysis, IR, 1 H NMR, and single-crystal X-ray diffraction. The X-ray diffraction analysis revealed that 3 a^3 c crystallize in monoclinic with space group Cc. The units of 3 a ~ 3 c were linked by intermolecular N–H...X(X = Cl, Br, I) hydrogen bonds into 2 D layered structures, which were further extended into 3 D networks by a series of π-π stacking interactions. Thermogravimetric analysis showed that all of them possessed higher thermal stabilities. The reactivities toward calf thymus DNA(ct-DNA) and bovine serum albumin(BSA) of 3 a^3 c were investigated by UV-vis and fluorescent spectroscopy as well as molecular docking simulation. Both theoretical and experimental results indicated that 3 a^3 c bound to ct-DNA in the mode of minor groove binding, and interacted with BSA through the hydrophobic cavity near TRP213. Besides, the orders of binding affinities of 3 a^3 c to ct-DNA and BSA were both 3 c > 3 b > 3 a, which were the same as that of antibacterial activities. Thus, the interactions of iodinated acylhydrazone with biological targets were stronger than that of chlorinated and brominated acylhydrazones, which provided a representative case for halogenation of lead compounds in rational drug design.