Synthesis, Crystal Structure, and Cytotoxic Property of Di（μ1”,1”-azide）bis（4-nitro-2-（3＇-dimethylaminon-propylimino）methylenephenolate）dizinc（Ⅱ）

The title azide-bridged dinuclear Schiff base zinc(Ⅱ) complex [Zn2(C12H16N3O3)2-(μ1,1-N3)2] was prepared and characterized by elemental analysis, IR spectrum, and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group F21/n with a = 8.736(2), b = 14.850(3), c = 11.775(2) (A), β = 102.42(3)°, V= 1491.8(5) (A)3, Z= 2, Dc = 1.593 g/cm3, Mr = 715.36, λ(MoKα) = 0.71073 (A), μ = 1.669 mm-1, F(000) = 736, the final R = 0.0338 and wR = 0.0789. A total of 3411 unique reflections were collected, of which 2777 with Ⅰ＞2σ(Ⅰ) were observed. The molecule of the complex is located on a crystallographic inversion centre. Each Zn atom in the complex is five-coordinated by one Schiff base ligand and two bridging azide groups, forming a trigonal bipyramidal configuration. The Zn…Zn distance is 3.328(2) (A). In the crystal structure, molecules are linked through intermolecular C-H…N hydrogen bonds, forming layers parallel to the bc plane. The complex shows low cytotoxic property to both normal and carcinoma cells.     

Synthesis,Crystal Structure,and Cytotoxic Property of Di(μ1’’,1’’-azide)bis(4-nitro-2-(3'-dimethylamino- n-propylimino)methylenephenolate)dizinc(Ⅱ)

The title azide-bridged dinuclear Schiff base zinc(II) complex [Zn2(C12H16N3O3)2- (μ1,1-N3)2] was prepared and characterized by elemental analysis, IR spectrum, and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/n with a = 8.736(2), b = 14.850(3), c = 11.775(2) , β = 102.42(3)o, V = 1491.8(5) 3, Z = 2, Dc = 1.593 g/cm3, Mr = 715.36, λ(MoKα) = 0.71073 , μ = 1.669 mm-1, F(000) = 736, the final R = 0.0338 and wR = 0.0789. A total of 3411 unique reflections were collected, of which 2777 with I > 2σ(I) were observed. The molecule of the complex is located on a crystallographic inversion centre. Each Zn atom in the complex is five-coordinated by one Schiff base ligand and two bridging azide groups, forming a trigonal bipyramidal configuration. The Zn···Zn distance is 3.328(2) . In the crystal structure, molecules are linked through intermolecular C–H···N hydrogen bonds, forming layers parallel to the bc plane. The complex shows low cytotoxic property to both normal and carcinoma cells.     

Synthesis and Structure of Dibenzoyl-bissemicarbazone Neodymium(Ⅲ) Perchlorate

A new Schiff base Dibenzoyl-bissemicarbazone C15H16N6O2(L) and its complex with neodymium(Ⅲ ) perchlorate [NdL2(H2O)2](ClO4)3 were synthesized. The crystal and molecular structure of the title complex were determined by single crystal X-ray diffraction. The crystal is monoclinic and conforms to space group P. with cell constants a=10. 893(2) A, b= 12. 118(3) A , c=22. 494(5) A , β=89. 86(3)% V = 2969.19A3. The final standard deviation R=0. 0919. In the complex Nd is coordinated by four nitrogen and six oxygen atoms, of which four nitrogen and four oxygen atoms are provided by two neutral ligands L, and the other two oxygen atoms are provided by two water molecules, forming a ten-coordinated complex cation, which the perchlorate groups exist in the outer sphere. The coordination polyhedron takes a bicapped anti-square prism arrangement. That the average bond length of Nd-N is 2. 735 A indicates that the coordination of N in groups to Nd( Ⅲ ) is very weak.     

Synthesis,Crystal Structure,and Cytotoxic Property of Dibromobis{4-bromo-2-[(2-phenylaminoethylimino)methyl]phenolato}dizinc(Ⅱ)

The title phenolic oxygen bridged dinuclear Schiff base zinc(Ⅱ)complex [Zn2Br2-(C15H14BrN2O)2]was synthesized and characterized by elemental analysis and single-crystal X-ray diffraction.The crystal belongs to the trielinic system,space group P-1 with a=9.2279(17),b=12.096(2),c=16.286(3)(A),α=75.402(3),β=87.464(3),γ=72.746(3)°,V=1679.1(5)(A)3,Z=2,Dc=1.833 g/cm3,Mr=926.94,λ(MoKα)=0.71073(A),μ=6.221 mm-1,F(000)=904,the final R=0.0601 and wR=0.1155.A total of 7453 unique reflections were collected,of which 3425 with Ⅰ＞2σ(Ⅰ)were observed.One Zn atom is six-coordinate in an octahedral geometry,and the other one is four-coordinate in atetrahedral geometry.The Zn…Zn distance is 3.106(2) (A).In the crystal structure,molecules are linked through intermolecular hydrogen bonds typed N-H…Br and C-H…Br,forming zigzag chains running along the b axis.The complex shows potent cytotoxic property to both normal and cardnoma cells.     

Synthesis and Crystal Structure of Di-μ1,1-azido-bis((azido)[N-ethyl-N''-(1-pyridin-2-ylmethylidene)ethane-1,2-diamino]cadmium(Ⅱ))

The dinuclear Schiff base cadmium(Ⅱ) complex [Cd2(C10H15N3)2(N3)2 (μ1,1-N3)2] was prepared and characterized by elemental analysis, IR spectrum, and single-crystal X-ray dif- fraction. The crystal belongs to the monoclinic system, space group P21/n with a = 10.819(2), b = 11.058(2), c = 12.766(3)(A), β = 102.456(2)°, V = 1491.3(7)(A)3, Z = 2, Dc = 1.665 g/cm3, Mr = 747.42, λ(MoKα) = 0.71073 (A), μ = 1.470 mm-1, F(000) = 744, R = 0.0307 and wR = 0.0584. A total of 3420 unique reflections were collected, of which 2575 with Ⅰ ＞ 2σ(Ⅰ) were observed. There is a crystallographic inversion centre at the midpoint of the two metal atoms in the complex. Each CdⅡ atom in the complex is in a distorted octahedral coordination. The molecules in the crystal are linked through the intermolecular hydrogen bonds of N-H…N and C-H…N, forming a three- dimensional network.     

Synthesis and Crystal Structure of Bis{2-bromo- 4-chloro-6-[(2-isopropylammonioethylimino)-methyl]phenolato}bisthiocyanatozinc(Ⅱ)

A Schiff base zinc(Ⅱ) complex [Zn(C12H16BrClN2O)2(NCS)2] was prepared and characterized by elemental analysis, IR and single-crystal X-ray diffraction. The crystal belongs to the triclinic system, space group P with a = 8.414(1), b = 9.124(1), c = 22.212(3) (A), α = 79.177(2), β = 86.296(2), γ = 89.899(2)o, V = 1671.3(4) (A)3, Z = 2, Dc = 1.631 g/cm3, Mr = 820.79, λ(MoKα) = 0.71073 (A), μ = 3.444 mm-1, F(000) = 824, R = 0.0646 and wR = 0.1179. A total of 7371 unique reflections were collected, of which 3904 with I＞2σ(I) were observed. The complex crystallizes with two half-molecules per asymmetric unit and each mononuclear molecule is centrosymmetric. The Zn atom lying at the inversion centre is six-coordinated in a slightly distorted octahedral geometry by two phenolate O atoms and two imine N atoms from two Schiff base ligands, as well as two N atoms from two thiocyanate anions. In the crystal structure, the combination of π-π stacking interactions and intermolecular hydrogen bonds (N-H…Br, N-H…O, N-H…N, C-H…O, C-H…S and C-H…Cl) leads to a three-dimensional network.     

Synthesis and Crystal Structure of Bis{2-bromo- 4-chloro-6-[（2-isopropylammonioethylimino）- methyl]phenolato}bisthiocyanatozinc（Ⅱ）

A Schiff base zinc(Ⅱ) complex [Zn(C12H16BrClN2O)2(NCS)2] was prepared and characterized by elemental analysis,IR and single-crystal X-ray diffraction. The crystal belongs to the triclinic system,space group P1 with a=8.414(1),b=9.124(1),c=22.212(3),α=79.177(2),β=86.296(2),γ=89.899(2)o,V=1671.3(4)3,Z=2,Dc=1.631 g/cm3,Mr=820.79,λ(MoKα)= 0.71073,μ=3.444 mm-1,F(000)=824,R=0.0646 and wR=0.1179. A total of 7371 unique reflections were collected,of which 3904 with I > 2σ(I) were observed. The complex crystallizes with two half-molecules per asymmetric unit and each mononuclear molecule is centrosymmetric. The Zn atom lying at the inversion centre is six-coordinated in a slightly distorted octahedral geometry by two phenolate O atoms and two imine N atoms from two Schiff base ligands,as well as two N atoms from two thiocyanate anions. In the crystal structure,the combination of π-π stacking interactions and intermolecular hydrogen bonds (N–H…Br,N–H…O,N–H…N,C–H…O,C–H…S and C–H…Cl) leads to a three-dimensional network.     

Synthesis,Crystal Structure,and Cytotoxic Property of Dibromobis{4-bromo-2-[（2- phenylaminoethylimino）methyl]phenolato}dizinc（II）

The title phenolic oxygen bridged dinuclear Schiff base zinc（II） complex [Zn2Br2- （C15H14BrN2O）2] was synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The crystal belongs to the triclinic system, space group P1 with a = 9.2279（17）, b = 12.096（2）, c = 16.286（3） A, α = 75.402（3）, β = 87.464（3）, γ= 72.746（3）°, V = 1679.1（5） A^3, Z = 2, Dc = 1.833 g/cm^3, Mr = 926.94, λ（MoKα） = 0.71073 A, μ= 6.221 mm^-1, F（000） = 904, the final R = 0.0601 and wR = 0.1155. A total of 7453 unique reflections were collected, of which 3425 with I 〉 2σ（I） were observed. One Zn atom is six-coordinate in an octahedral geometry, and the other one is four-coordinate in a tetrahedral geometry. The Zn...Zn distance is 3.106（2） A. In the crystal structure, molecules are linked through intermolecular hydrogen bonds typed N-H...Br and C-H...Br, forming zigzag chains running along the b axis. The complex shows potent cytotoxic property to both normal and carcinoma cells.     

Synthesis and Crystal Structure of Di-μ_(1,1)-azido-bis((azido)[N-ethyl-N'-(1-pyridin-2-ylmethylidene)ethane-1,2-diamino]cadmium(Ⅱ))

The dinuclear Schiff base cadmium(II) complex [Cd2(C10H15N3)2(N3)2 (μ1,1-N3)2] was prepared and characterized by elemental analysis, IR spectrum, and single-crystal X-ray dif- fraction. The crystal belongs to the monoclinic system, space group P21/n with a = 10.819(2), b = 11.058(2), c = 12.766(3) , β = 102.456(2)o, V = 1491.3(7) 3, Z = 2, Dc = 1.665 g/cm3, Mr = 747.42, λ(MoKα) = 0.71073 , μ = 1.470 mm-1, F(000) = 744, R = 0.0307 and wR = 0.0584. A total of 3420 unique reflections were collected, of which 2575 with I > 2σ(I) were observed. There is a crystallographic inversion centre at the midpoint of the two metal atoms in the complex. Each CdII atom in the complex is in a distorted octahedral coordination. The molecules in the crystal are linked through the intermolecular hydrogen bonds of N–H···N and C–H···N, forming a three- dimensional network.     

Syntheses,Crystal Structures and Antibacterial Activities of Schiff Base Ligand and Its Nickel(Ⅱ) Complex

A complex [NiL2] was synthesized, in which L, or to be exact, a Schiff base ligand(HL), was derived from the condensation of 1-phenyl-3-methyl-4-phenylacetyl-5-pyrazolone(PMPAP) with L-phenylalanine methyl ester. They were characterized by IR and single-crystal X-ray diffraction. Green block crystals of both ligand and its complex were grown at room temperature. The ligand, which consists of two individual fragments, crystalizes in the P1 space group(a = 5.6268(5), b = 10.6892(11) and c = 19.4869(18) ). The complex crystalizes in the P21 space group(a = 21.4076(18), b = 9.4792(8) and c = 25.287(2) ), which consists of a nickel six-coordinated compound. Every fragment is a distorted octahedron with four oxygen and two nitrogen atoms. The Schiff base ligand(HL) and its complex have been tested in vitro to evaluate their antibacterial activity against bacteria Escherichia Coli and Bacillus subtilis. It is found that the complex has higher activity than the corresponding free Schiff base ligand(HL) against the same bacterial.     

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

A new Schiff base compound, C13H9Br2N3O2·CH3OH, 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) , α = 92.940(2), β = 110.456(2), γ = 96.040(2)o, Z = 2, V = 814.0(2) 3, Dc = 1.759 g/cm3, Mr = 431.09, λ(MoKα) = 0.71073 , 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 > 2σ(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)o. 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 Diaquabis{2,4-dibromo-6-[(2-ethylaminoethylimino)methyl]phenolato}nickel(Ⅱ) Dinitrate Diacetonitrile

The title mononuclear Schiff base nickel(Ⅱ) complex [Ni(C11H14Br2N2O)2(H2O)2]·2NO3·2C2H3N was prepared and characterized by elemental analysis, IR spectrum, and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/n with a = 15.534(2), b = 7.647(1), c = 16.435(2) (A), β = 103.252(2)o, V = 1900.3(4) (A)3, Z = 2, Dc = 1.750 g/cm3, Mr = 1000.99, λ(MoKα) = 0.71073 (A), μ = 4.776 mm-1, F(000) = 996, the final R = 0.0368 and wR = 0.0724. A total of 3988 unique reflections were collected, of which 2764 with I＞2σ(I) were observed. The complex consists of a mononuclear [Ni(C11H14Br2N2O)2(H2O)2]2 cation, two nitrate anions and two acetonitrile molecules. The Ni atom, lying on the inversion centre, is six- coordinated by two Schiff bases and two water molecules to assume an octahedral coordination geometry. The molecules in the crystal are linked through intermolecular hydrogen bonds of N-H…O, N-H…Br, O-H…O, O-H…N and C-H…O to form layers.     

A new oxidovanadium(Ⅳ) Schiff base complex containing asymmetric tetradentate ONN0O0Schiff base ligand:Synthesis,characterization,crystal structure determination,thermal study and catalytic activity

After synthesis of an asymmetric tetradentate ONN0O0 Schiff base ligand(H2L) followed by reaction of the synthesized H2 L with an equimolar mixture of methanolic solutions of the VO(acac)2, a new oxidovanadium(IV) Schiff base complex(VOL) was synthesized. The Schiff base ligand and its complex were characterized by FT-IR and UV–vis spectra and C, H, N analysis. The crystal structure of VOL was also determined by single crystal X-ray analysis. The VOL complex crystallizes in monoclinic space group Cc. The Schiff base ligand acts as a tetradentate ligand through its two iminic nitrogens and two phenolic and acetylacetonate oxygens. Thermogravimetric analysis of the VOL showed that it decomposes in two steps and converts to mixed vanadium oxides at 477 8C. In addition, thermal decomposition of the VOL complex in air at 660 8C leads to formation of V2O5 nanoparticles with the average size estimated from XRD 49 nm. The catalytic activity of the VOL complex was investigated in the epoxidation reaction and different reaction parameters were optimized. The results showed that the cyclic alkenes were efficiently converted to the corresponding epoxides, whereas the VOL did not appreciably convert the linear alkenes.     

Synthesis and Crystal Structure of Diaquabis{2,4- dibromo-6-[（2-ethylaminoethylimino）methyl]- phenolato}nickel（II） Dinitrate Diacetonitrile

The title mononuclear Schiff base nickel(Ⅱ) complex [Ni(C11H14Br2N2O)2(H2O)2]·2NO3·2C2H3N was prepared and characterized by elemental analysis, IR spectrum, and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/n with a = 15.534(2), b = 7.647(1), c = 16.435(2) (A), β = 103.252(2)o, V = 1900.3(4) (A)3, Z = 2, Dc = 1.750 g/cm3, Mr = 1000.99, λ(MoKα) = 0.71073 (A), μ = 4.776 mm-1, F(000) = 996, the final R = 0.0368 and wR = 0.0724. A total of 3988 unique reflections were collected, of which 2764 with I＞2σ(I) were observed. The complex consists of a mononuclear [Ni(C11H14Br2N2O)2(H2O)2]2 cation, two nitrate anions and two acetonitrile molecules. The Ni atom, lying on the inversion centre, is six- coordinated by two Schiff bases and two water molecules to assume an octahedral coordination geometry. The molecules in the crystal are linked through intermolecular hydrogen bonds of N-H…O, N-H…Br, O-H…O, O-H…N and C-H…O to form layers.     

Synthesis,Crystal Structure and Cytotoxic Activity of a Zinc（Ⅱ） Complex of the Schiff Base Derived from S-benzyldithiocarbazate

A novel zinc(Ⅱ) complex of empirical formula,ZnL2(L=anionic forms of S-benzyl-β-N-(2,4-dichlorobenzylidene) hydrazine carbodithioate),has been synthesized and characterized by elemental analysis,IR spectra and single-crystal X-ray diffraction.The crystal belongs to the triclinic system,space group P with a = 9.3168(9),b = 13.0353(13),c = 14.7702(15) ,α = 71.2860(10),= 87.5140(10),γ = 79.4480(10)o,V = 1670.0(3) 3,Z = 2,Mr = 773.93,Dc = 1.539 g/cm3,μ = 1.334 mm-1,F(000) = 784,the final R = 0.0403 and wR = 0.0800 for 4060 observed reflections with I>2(I).In the crystal structure,the zinc(Ⅱ) complex has a distorted tetrahedral geometry in which the zinc ion is coordinated by the nitrogen and sulfur atoms from two Schiff base ligands,respectively.The preliminary bioassay indicates that the Schiff base and its zinc complex exhibit inhibitory activity against the human gastric cancer cell lines(MKN45) and hepatoma cell lines(HepG2).     

Synthesis and Crystal Structure of Di-μ1,1-azido-bis（（azido）[N-ethyl-N＇-（1-pyridin-2-ylmethylidene）ethane-1,2-diamino]cadmium（Ⅱ））

The dinuclear Schiff base cadmium（Ⅱ） complex [Cd2（C10H15N3）2（N3）2 （μ1,1-N3）2] was prepared and characterized by elemental analysis, IR spectrum, and single-crystal X-ray dif- fraction. The crystal belongs to the monoclinic system, space group P21/n with a = 10.819（2）, b = 11.058（2）, c = 12.766（3）A, β = 102.456（2）°, V = 1491.3（7）A^3, Z = 2, Dc = 1.665 g/cm^3, Mr = 747.42, λ（MoKα） = 0.71073 （A）, μ = 1.470 mm^-1, F（000） = 744, R = 0.0307 and wR = 0.0584. A total of 3420 unique reflections were collected, of which 2575 with Ⅰ 〉 2σ（Ⅰ） were observed. There is a crystallographic inversion centre at the midpoint of the two metal atoms in the complex. Each CdⅡ atom in the complex is in a distorted octahedral coordination. The molecules in the crystal are linked through the intermolecular hydrogen bonds of N-H…N and C-H…N, forming a three- dimensional network.     

A New Method of Synthesis of Azo Schiff Base Ligands with Azo and Azomethine Donors: Synthesis of N-4-Methoxy- benzylidene-2-(3-hydroxyphenylazo)-5-hydroxy- aniline and Its Nickel(II) Complex

A new method for the synthesis of azo Schiff an base ligand in which the azo and azomethine groups are coordination sites was developed through a Schiff base precursor. The precursor, N-4-methoxybenzylidene-3-hydroxy- phenylamine (SB) derived from 3-aminophenol was regioselectively coupled with a diazonium ion para to the hydroxyl group of the amine component of the Schiff base. The para selectivity was controlled by the directing effect of the hydroxyl group. The ligand and its nickel(II) complex were characterized by elemental analyses, IR and UV-Vis spectroscopy. The analytical and spectral data supported the mononuclear formulation of the complex with metal to ligand ratio (M∶L＝1∶2) and suggested a square planar geometry for the complex.     

A New Method of Synthesis of Azo Schiff Base Ligands with Azo and Azomethine Donors： Synthesis of N-4-Methoxybenzylidene-2-（3-hydroxyphenylazo）-5-hydroxyaniline and Its Nickel（Ⅱ） Complex

A new method for the synthesis of azo Schiff an base ligand in which the azo and azomethine groups are coordination sites was developed through a Schiff base precursor. The precursor, N-4-methoxybenzylidene-3-hydroxyphenylamine （SB） derived from 3-aminophenol was regioselectively coupled with a diazonium ion para to the hydroxyl group of the amine component of the Schiff base. The para selectivity was controlled by the directing effect of the hydroxyl group. The ligand and its nickel（Ⅱ） complex were characterized by elemental analyses, IR and UV-Vis spectroscopy. The analytical and spectral data supported the mononuclear formulation of the complex with metal to ligand ratio （M ： L = 1 ： 2） and suggested a square planar geometry for the complex.     

Synthesis and Crystal Structure of a Novel Fe(Ⅲ) Schiff Base Complex

A novel Fe(Ⅲ) Schiff base complex,FeⅢ(HL) {H4L = 1,1,1,1-tetrakis[(salicylaldimino)methyl]methane},has been prepared and characterized by elemental analyses,IR spectrum,and single-crystal X-ray diffraction analysis.The crystal belongs to the monoclinic system,space group P21/n with a = 12.569(3),b = 12.955(3),c = 17.647(4) ,β = 91.896(9)°,V = 2871.9(1) 3,Z = 4,Dc = 1.391 g/cm3,F(000) = 1252.0,Mr = 601.45,R = 0.0383 and wR = 0.1025.The structural analysis reveals that the Fe(Ⅲ) ions are six-coordinated by imine nitrogen atoms and phenolic oxygen atoms form three pendant arms of Schiff base ligands,and one of the salicylaldimine chelating units remains uncoordinated.Discrete complex molecules were further assembled into 1D supramolecular aggregations by C-H…O hydrogen bonding and C-H…π interactions.     

Synthesis and Crystal Structure of Diaquabis{2,4-dibromo-6-[(2-ethylaminoethylimino)methyl]-phenolato}nickel(Ⅱ) Dinitrate Diacetonitrile

The title mononuclear Schiff base nickel(Ⅱ) complex [Ni(C11H14Br2N2O)2(H2O)2]· 2NO3·2C2H3N was prepared and characterized by elemental analysis,IR spectrum,and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system,space group P21/n with a=15.534(2),b=7.647(1),c=16.435(2),β=103.252(2)o,V=1900.3(4)3,Z=2,Dc=1.750 g/cm3,Mr=1000.99,λ(MoKα)=0.71073,μ=4.776 mm-1,F(000)=996,the final R=0.0368 and wR=0.0724. A total of 3988 unique reflections were collected,of which 2764 with I > 2σ(I) were observed. The complex consists of a mononuclear [Ni(C11H14Br2N2O)2(H2O)2]2+ cation,two nitrate anions and two acetonitrile molecules. The Ni atom,lying on the inversion centre,is six-coordinated by two Schiff bases and two water molecules to assume an octahedral coordination geometry. The molecules in the crystal are linked through intermolecular hydrogen bonds of N–H…O,N–H…Br,O–H…O,O–H…N and C–H…O to form layers.