Synthesis and c haracterization of ligands d erived 2-hydroxy-1-naphthaldehy d e and their complexes with divalent metal ions ( Mn + 2 , Fe + 2 , Ni + 2 )

In this work, Schiff base ligands L1: N, N-bis (2-hydroxy-1-naphthaldehyde) hydrazine, L2: N, N-bis (salicylidene) hydrazine, and L3:N –salicylidene- hydrazine were synthesized by condensation reaction. The prepared ligands were reacted with specific divalent metal ions such as (Mn2+, Fe2+, Ni2+) to prepare their complexes. The ligands and complexes were characterized by C.H.N, FT-IR, UV-Vis, solubility, melting point and magnetic susceptibility measurements. The results show that the ligands of complexes (Mn2+, Fe2+) have octahedral geometry while the ligands of complexes (Ni2+) have tetrahedral geometry.


Introduction
In the last decade, there has been a dramatic growth of the interest inorganic complex based material that exhibit unusual properties [1][2][3][4][5].The chemical organic compound containing azomethin group (-HC=N-) and anils derived from an amines and aldehyde or keton.The coordination of these ligands and metals are an important DOI: 10.20723/ijp.16.37.79-87 class of ligands coordinate to metal ion are very important in the development of coordination chemistry.These complexes have a lot of uses such as, applications of medical and pharmaceutical, biology, industrial [6][7][8][9][10][11].In this work, metal ions like (Mn 2+ , Fe 2+ , Ni 2+ ) complexes were synthesized and characterized by elemental analyses, IR, UV, and magnetic susceptibilities.The Schiff bases were also synthesized and their structures investigated by elemental analyses, FT-IR, and UV spectra then compared with their complexes.

Experiments
Preparation of ligand: N, N-bis (2hydroxy-1-naphthaldehyde) hydrazine: a mixture of hydrazine (0.6g, 0.01mmol) in (15 ml) ethanol with (0.72 g, 0.02 mmol) aldehyde in ethanol refluxed for the chemical equation of 2h then concentrated of the solution.The precipitate was separated by filtration, washed with ethanol and then air-dried.Fig. 1 shows the ligand preparation.The IR spectra of ligands and its complexes are obtained by Fourier transform infrared spectroscopy (FTIR) Japan-Shimadzu uses KBr substrates.In order to study the optical properties of prepared samples, the absorbance measurements were carried out by using UV/Visible Shimadzu -Japan spectrophotometer.The elemental micro analysis of C,H,N was carried out by EuroEA 3000 system.

Results and discussion
The prepared ligands were studied and characterized by using the following techniques:

Elemental microanalysis (C,H,N)
The results obtained from Elemental Microanalysis (C.H.N) for show high agreement with calculated theoretical weight percentage as shown in Table 1.

Solubility
The solubility of prepared compounds were experimented in organic solvents and distilled water which shown in Table 2:

Magnetic susceptibility measurements
The magnetic sensitivity of prepared compounds were measured by using device of Auto magnetic susceptibility Balance sherwood scientific as shown in Table 3.  [2,7,11].

Infrared spectral studies
The prepared ligands and complexes were studied by FTIR spectroscopy.The results show that the main bands are related to: absorption bands at 1324-1340 cm -1 which attributed to the vibrations of (C-O) while the (C=N) group appears in 1610 -1637 cm -1 .Also the (C-H) group observed at 750-460 cm -1 which attributed to (M-O) and (M-N) vibration.(O-H) group is clear appeared at 3400 cm -1 .The FTIR spectra of prepared compounds are shown in Figs.2-7 and Table 4 shows the summarized results of all compounds.

UV-VIS spectroscopy
UV-Vis spectra of ligands were studied using dimethyl sulfoxide (DMSO) at 10 -3 mol at room temperature.The spectrum of ligand (L 1 ) shows two absorption bands at 284 nm wavelength and the molar absorptivity ϵmax=1716 L.mol -1 .cm - .This result attributed to the electronic transitions (*), while the molar absorptivitymax at 357 nm equals to 983 L. mol -1 .cm - attributed to n * electronic transitions [2].
The UV-VIS spectrum of ligand [Fe-L 3 ] shows that the absorption bands appears at 241 nm withmax = 1925 L.mol -1 .cm - which attributed to charge transitions at 740 nm the max= 80 L.mol -1 .cm - attributed to the electronic transitions of 6 A1g → 4 Eg(G) and at 887 nm with max = 70 L.mol -1 .cm - attributed 6 A1g → 4 T 2 g(G) according to above result and analysis we can suggested that the ligand with orthorhombic geometry.On other hand, the ligand [Ni-L 3 ] spectra appears that the absorption bands located at 245 nm with max = 2350 L.mol -1 .cm - result of charge transitions while at 326 nm themax= 689 L.mol -1 .cm - attributed to electronic transitions of 6 A1g → 4 T 2 g(G) these spectra absorption result that the suggestion of the ligand with tetrahedral [11,12].Table 5 refers absorption locations of prepared ligand from UV-VIs spectra.

Conclusions
The (Mn +2 , Fe +2 , Ni +2 ) complexes are coloured, insoluble in most of the organic solvent but soluble in DMF and DMSO.C.H.N, FT-IR, UV-VIS, and N.M.R analysis were carried out to characterize the prepared ligands.The infrared spectral data indicate that all the ligands act as mononegative bidentate species towards (Mn +2 , Fe +2 , Ni +2 ) complexes.Electronic spectra supported by magnetic moment revealed orthorhombic geometry for ligand L1 and tetrahedral geometry for ligand L2 and L3.