Synthesis and characterization of a new complex based on antibiotic: Zirconium complex

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The detailed study of the crystalline structure of the three forms of sulfanilamide [19][20][21][22][23] and the characterization of sulfanilamide and its complex derivatives have been reported [24][25][26][27].Meanwhile, sulfonamides have attracted increasing attention to supramolecular chemistry and supramolecular medicinal chemistry [28], as it combines the functionalities required for various biological activities and the coordination of the metal through phenylamino groups and sulfonylamino groups.Recently, modification of existing drugs through better coordination at a metal center has attracted considerable interest [29][30][31][32][33].
In this study, the coordination of sulfanilamide ligand with transition metals was studied and the synthesis and structure of a novel sulfanilamide complex, nitro (4-aminobenzenesulfonamide) zirconium, is presented.
Characterization of the complex was performed by infrared spectroscopic, thermogravimetric (TG) and elemental analysis methods.
In addition, the technique of X-ray diffraction was used and the structural studies of the complex are represented.

Materials and methods
The complex was obtained by dissolving PbZrO 3 in a solvent and then adding sulfanilamide H 2 NC 6 H 4 O 4 NH 2 with stirring in a hydrothermal bomb.The principle of this method is to introduce the dissolved reagents into a Teflon-coated stainless steel autoclave which is heated to increase the pressure in a chamber set at a constant temperature of 120°C for 72 h.
Then, the bomb is cooled after taking out from the enclosure.
After that, the powder was washed several times and filtered and let to evaporate in the open air.
After several days, orange crystals appeared as needles, which are insoluble in water, Figure 2.
The Fourier transform infrared (FTIR) spectrometer, Thermo Nicolet Nexus 670, was used for the determination of the sulfamide bonds.
Complex (1) was studied by single crystal X-ray diffraction.The crystallographic measurements were carried out at 293 K on an APEX2 CCD automatic diffractometer [34] using molybdenum Kα radiation (λ = 0.71073 Å) and a graphical monochromator equipped with a cryogenic system allowing low temperature recording.The refinement and the reduction of the data of the structure were realized by the software SAINT [34].
The structure has been resolved using the SIR-2002 program [35] and then refined using the least squares method with the program: SHELXL-2013 [36], these programs are found in the complete WINGX software [37].Graphical representations were made using software: ORTEP-3 [38], Mercury [39] and DIAMOND [40].
The thermal study of the compound, [Zr(C 12 H 17 N 4 O 4 S 2 ) 2 ] 2+ • 2(NO 3 ) − , was performed byTG on a "Setaram Setsys 16/18" thermo balance under vacuum under oxidizing atmosphere (O 2 ), 40 ml/min.In a typical experiment, 3-5 mg of the sample was heated from 0 to 1,000°C at a heating rate of 10°C/min, this amount of sample gave a full-scale deviation with instrument used.

FTIR analysis
In order to specify the binding mode and the effect of metal ions on the sulfanilamide ligand [41][42][43][44][45][46], the free ligand IR spectra and the synthesized Zr (1) and Zn (2) [47] metal complexes were studied and assigned on the basis of a careful comparison of their spectra (Figures 3-5).The number of calculated vibration waves, positions and assignments for sulfanilamide is compared with the two synthesized products shown in Table 1.

DRX analysis
The crystallizes in a space group (Pbca) of the orthorhombic system.This complex differs from the complex (2) by the coordination of the sulfanilamide ligand.The asymmetric unit comprises a metal ion Zr(II), two metal-coordinated sulfanilamide ligands and a crystallographically independent nitro anion, all located at general positions (Figure 6).

TG analysis
The TG analysis provides a precise indication of the overall mass loss, but provides no indication of the nature of the gases emitted.
The TG analysis of the compound

FTIR links
Recently, some structural and vibrational research works have been reported for sulfanilamide and its metal complexes.Table 1: Number of calculated vibration waves, positions and assignments for the sulfanilamide and complex (1) and (2) measured by infrared   In their study, the number of calculated vibration waves, positions and assignments for the two synthesized products are presented in Table 1 and compared with the literature data.
The results found are in good agreement with the literature data.
The sulfanilamide ligand adopts a "bidentate" coordination mode in repetitive and symmetrical chain.The latter coordinates in two ways: the first ligand coordinates the metal with oxygen O1 of the sulfonylamino function and nitrogen N1 of the phenylamino function, while the second ligand coordinates the metal with the N3 nitrogen of the phenylamino function and the N4 nitrogen of the sulfonylamino function.This coordination mode generates the polymer structure shown in Figure 9.
As for the nitrate anion that accompanies the zirconium complex is not coordinated, each − NO 3 anion entity accompanies a metal.
The sequence of zirconium polyhedra with sulfanilamide ligands is shown in Figure 10 on the (a-c) plane.The arrangement of these tetrahedra appears in the form of metal layers separated by the organic layers of the sulfanilamide.Note that each pair of polyhedra is inverted relative to each other, accompanied by − NO 3 nitro anion pair.

Hydrogen bonds
The structure of the sulfanilamide ligand confers on the complex (1), a polynuclear structure.Thus, within this structure, the cohesion between the molecules is essentially ensured by two types of intra and intermolecular hydrogen interactions Figure 11, Table 3.

Intramolecular hydrogen interactions, in the case of chelate ligands
Four intramolecular hydrogen bonds connect the nitrogen atoms (donors: D) of the sulfanilamide and the oxygen atom (acceptors: A) of the nitro anion − NO 3 ; they also con- nect the carbon atoms (donors: D) of the sulfanilamide and the oxygen atom (acceptors: A) of the sulfanilamide function of the ligand, (Figure 11).The data for these intramolecular interactions are summarized in Table 3.
According to Steiner [50], hydrogen bonds can be classified into three different categories based on distances: D-A, H.A and angles D-H.A (Table 3).
The structure of the complex (1) also reveals the existence of intermolecular interactions of the hydrogen type.These bridges involve contacts N-H.O (Table 3, Figure 11) which generates a three-dimensional network of hydrogen bonds of moderate strength [42] (distance D. A between 2.5 and 3.2 Å and angles D-H.A superior at 130°) and other low (distance D. A > 3.2 Å and angles D-H.A greater than 90°) ensuring the junction between the different ligands of the cation and the anion between the molecules of the crystal lattice.The very close weak bonds are explained by the association between two large molecules.The refinement was done by geometric calculation.The lengths and angles of the hydrogen bonds, listed in Table 2, are of the same order of magnitude as those observed in complexes containing sulfanilamide [51][52][53][54][55].

TG properties of complex (1)
The TG curve of the ligand alone of "sulfanilamide" already studied in the literature [56] can be used as a  Synthesis and characterization of a new complex based on antibiotic: Zr complex  5 qualitative tool in the identification of a new compound based on unknown sulfonamide by comparing its shape to the shape of the curve obtained, Figure 12.
Research on sulfanilamide and these derivatives was conducted to see if the curves could be obtained and if they were unique, so that the sulfonamide analysis could become a more practical analysis.Further development of the technique could lead to the determination of the components of a mixture and subsequently to a quantitative analysis of the drugs.Several articles concerning the thermal decomposition of sulfones [57,58] occurring according to reaction (I) have been published in the literature.
The zirconium complex has a thermal decomposition curve (Figure 7) different from that of the Zn (2) complex, similar to a number of sulfanilamide reported in the literature [59].It is stable up to 220°C or it begins to decompose continuously up to 660°C to give zirconium oxide with a total mass loss of 65%.

Conclusion
In the present work, the structural and spectroscopic characterizations and the TG analysis of a new Zr(II) complex were presented, these finding confirm that the formed complex could be applied as an efficient antibiotic.The complex (1) is a charged discrete structure that consists of a molybdenum metal ion coordinated to four sulfanilamide ligands and two − NO 3 nitrate anions.Sulfanilamide is "bidentate" in this coordination mode, where the first ligand coordinates the metal with an oxygen O of the sulfonylamino function and a nitrogen N of the phenylamino function, while the second ligand coordinates the metal with the nitrogen N of the phenylamino function and the N nitrogen of the sulfonylamino function.The structure is polynuclear.
The sulfanilamide compounds used for the prevention and treatment of bacterial infections in human biological systems have been investigated.Because the applications of "sulfadrugs" based on sulfanilamide metal have interesting antimicrobial activities.Our research on sulfanilamide-based inorganic compounds has allowed us to synthesize and characterize, by single-crystal X-ray diffraction, new compounds rich in inter and intramolecular interactions via hydrogen bonds between neutral or cationic and anionic entities.

Figure 3 :
Figure 3: IR spectrum of the sulfanilamide in the range of 4,000-400 cm −1 .

Figure 10 :
Figure 10: Chaining polyhedra formed by the environment of molybdenum in the plane (a-c).

Figure 11 :
Figure 11: Representation of inter and intramolecular interactions of hydrogen type in the asymmetric unit of complex (1).The blue dots represent the intramolecular interactions N-H...O, C-H...O, The red dots represent the intermolecular N-H...O interactions.