1-(2,4-Dinitrophenyl)-2-(( Z )-2-(( E )-4-fluorobenzylidene)-3,4-dihydronaphthalen-1(2 H )-ylidene)hydrazine

: The reaction of ( E )-2-(4-fluorobenzylidene)-3,4-dihydronaphthalen-1(2 H )-one and (2,4-dinitrophenyl)hydrazine in boiling ethanol containing hydrochloric acid (0.2 mL; 37%) for 1.5 h gave 1-(2,4-dinitrophenyl)-2-(2-(4-fluorobenzylidene)-3,4-dihydronaphthalen-1(2 H )-ylidene)hydrazine in a 90% yield. Various spectral analyses, including NMR, and X-ray crystallography established the structure of the newly synthesized hydrazone.


Introduction
Hydrazones and their derivatives are significantly important compounds in the pharmaceutical industry.They show activities against various conditions such as inflammation, leishmaniasis, cancer, and Alzheimer's [1][2][3][4].Hydrazone derivatives are used as drugs in the treatment of illnesses (e.g., leprosy, tuberculosis, and mental disorders) and as fungicides [5,6].The use of hydrazones enables improvement in drug delivery through site-specific drug release, including to areas such as tumor tissue or thrombosis [7][8][9].
Substituted hydrazones also possess properties that make them useful as metalextracting agents [10].Schiff base hydrazones have a variety of applications in analytical chemistry, including the selective extraction of certain transition metals and their use in spectroscopic determination [11,12].Additionally, hydrazones are versatile compounds that can be used in the construction of sensor materials for detecting fluoride ions, cyanide ions, heavy metals, and poisonous fumes [13][14][15][16][17].
Recently, the synthesis and structure elucidation of a range of new heterocycles have been explored [18][19][20].The title compound was synthesized in continuation of this work.Dinitrobenzenes display significant biological activities [21] and the dihydronaphthalene group has been investigated for its medicinal properties [22].The aim of this work was to generate a composite hydrazone containing 2,4-dinitrobenzene and 3,4-dihydronaphthalene moieties using a simple procedure.

IR and NMR Spectroscopy of 3
The IR spectrum of hydrazone 3 showed an absorption band at 3297 cm -1 due to the NH group.The absorption bands for the C=N and the C=C in aromatic moieties appeared at 1612 and 1589 cm -1 , respectively.
The 1 H NMR spectrum of 3 showed two multiplets at high field (2.76 and 2.92 ppm), each with 2H.These multiplets were attributed to the CH2-CH2 protons of the tetralin moiety.The NH proton appeared at a very high field (11.92 ppm).
In the 13 C NMR spectrum of 3, the carbon at the 4-position of the 4-fluorophenyl group was observed at a very low field (161.7 ppm) as a doublet with a large coupling constant of 243.8 Hz.The doublet was due to the coupling between the fluorine atom and the C atom.The C2/C6 of the 4-fluorophenyl group appeared at 130.8 ppm as a doublet with a small coupling constant of 8.3 Hz.Additionally, the C3/C5 of the 4-fluorophenyl group appeared at 115.5 ppm as a doublet with a coupling constant of 21.8 Hz.Furthermore, the C=N carbon appeared at 149.7 ppm, while the CH2-CH2 carbons of tetralin moiety appeared at very high field (26.8 and 30.4 ppm).The spectrum showed all other carbons within the range of the expected chemical shifts (See Supplementary Materials for the spectra).

IR and NMR Spectroscopy of 3
The IR spectrum of hydrazone 3 showed an absorption band at 3297 cm −1 due to the NH group.The absorption bands for the C=N and the C=C in aromatic moieties appeared at 1612 and 1589 cm −1 , respectively.
The 1 H NMR spectrum of 3 showed two multiplets at high field (2.76 and 2.92 ppm), each with 2H.These multiplets were attributed to the CH 2 -CH 2 protons of the tetralin moiety.The NH proton appeared at a very high field (11.92 ppm).
In the 13 C NMR spectrum of 3, the carbon at the 4-position of the 4-fluorophenyl group was observed at a very low field (161.7 ppm) as a doublet with a large coupling constant of 243.8 Hz.The doublet was due to the coupling between the fluorine atom and the C atom.The C2/C6 of the 4-fluorophenyl group appeared at 130.8 ppm as a doublet with a small coupling constant of 8.3 Hz.Additionally, the C3/C5 of the 4-fluorophenyl group appeared at 115.5 ppm as a doublet with a coupling constant of 21.8 Hz.Furthermore, the C=N carbon appeared at 149.7 ppm, while the CH 2 -CH 2 carbons of tetralin moiety appeared at very high field (26.8 and 30.4 ppm).The spectrum showed all other carbons within the range of the expected chemical shifts (See Supplementary Materials for the spectra).
In the tetrahydronaphthalene group, the nonhydrogen atoms are coplanar, apart from C9, which is offset from the least-squares plane of the rest of the atoms by 0.75 (1) Å.The plane of the fluoromethylbenzene group deviates from the planar part of the tetrahydronaphthalene group by an fmbenz/thnaph twist angle of 15.10 (10) • .The ring centroid of the fluoromethylbenzene group also deviates from the plane through the planar part of the tetrahydronaphthalene group by 0.94 Å.This deviation accounts for the configuration of the imine double bond as it gives the least hindered arrangement.The alternative configuration of the imine double bond would lead to an overlap of hydrogen atoms.A similar deviation is also observed in the structure of 2-(4-chlorobenzylidene)-3,4-dihydronaphthalen-1(2H) [23], in which the chlorobenzene group is twisted and offset from the tetrahydronaphthalene group.In the tetrahydronaphthalene group, the nonhydrogen atoms are coplanar, from C9, which is offset from the least-squares plane of the rest of the atoms by 0.75 The plane of the fluoromethylbenzene group deviates from the planar part of the te dronaphthalene group by an fmbenz/thnaph twist angle of 15.10 (10)°.The ring cen of the fluoromethylbenzene group also deviates from the plane through the planar p the tetrahydronaphthalene group by 0.94 Å.This deviation accounts for the configu of the imine double bond as it gives the least hindered arrangement.The alternativ figuration of the imine double bond would lead to an overlap of hydrogen atoms.A ilar deviation is also observed in the structure of 2-(4-chlorobenzylidene)-3,4 dronaphthalen-1(2H) [23], in which the chlorobenzene group is twisted and offset the tetrahydronaphthalene group.
Intramolecular N-H…O hydrogen bonding occurs in the molecule, with a N2 distance of 2.617(2) Å and N2-H2A…O1 angle of 128.3° (Figure 2a) and graph set g etry S(6).In the crystal, pairs of molecules related by inversion symmetry are link two intermolecular C-H…O contacts, with a C6…O2 distance of 3.388(3) Å and H6…O2 angle of 146.1°.The molecules are arranged with their molecular planes p to the (123) plane in the crystal (Figure 2b).

General
Chemicals, reagents, and analytical solvents were obtained from Merck.The IR spectrum of the title heterocycle was recorded on a Bruker Vertex 80 ATR-FTIR spectrometer (400-4000 cm -1 ).The NMR spectra, at 300 MHz for the 1 H and 75 MHz for 13 C were recorded in deuterated dimethyl sulfoxide (DMSO-d6) using a Varian Mercury 300 VX spectrometer.The chemical shift (δ) was reported in ppm and the coupling constant (J) was measured in Hz.Compound 1 was produced using a reported procedure [25].

General
Chemicals, reagents, and analytical solvents were obtained from Merck.The IR spectrum of the title heterocycle was recorded on a Bruker Vertex 80 ATR-FTIR spectrometer (400-4000 cm −1 ).The NMR spectra, at 300 MHz for the 1 H and 75 MHz for 13 C were recorded in deuterated dimethyl sulfoxide (DMSO-d 6 ) using a Varian Mercury 300 VX spectrometer.The chemical shift (δ) was reported in ppm and the coupling constant (J) was measured in Hz.Compound 1 was produced using a reported procedure [25].

Crystal Structure Determination
Data collection was conducted on an Agilent SuperNova Dual Atlas diffractometer using mirror monochromated MoKα radiation.The structure was solved with direct methods using SHELXS [26] and refined with SHELXL [27]

Conclusions
A novel 2,4-dinitrophenylhydrazone containing the 3,4-dihydronaphthalene moiety has been synthesized.The procedure used was simple and the yield obtained was high.The structure of the synthesized hydrazone was established using both nuclear magnetic resonance and X-ray diffraction.

Figure 2 .
Figure 2. (a) A segment of the crystal structure of 3 showing intra-and intermolecular contacts and (b) crystal packing viewed along the molecular plane.

Figure 2 .
Figure 2. (a) A segment of the crystal structure of 3 showing intra-and intermolecular contacts and (b) crystal packing viewed along the molecular plane.