Vibrational spectral analysis and first order hyperpolarizability calculations on (E)-N′-(furan-2-ylmethylene)nicotinohydrazide

The FT-IR, FT-Raman and UV-Vis spectra of (E)-N′-(furan-2-ylmethylene) nicotinohydrazide (F2CNH) was recorded and analyzed. The optimized geometrical parameters were calculated. The complete vibrational assignments were performed on the basis of TED analysis with the help of SQM method. The UV-Vis spectrum was recorded and analyzed. NBO analysis was carried out to explore the various conjucative/hyperconjucative interactions within the molecule and their second order stabilization energy. The HOMO and LUMO energy gap was studied. All theoretical calculations were performed on the basis of B3LYP/6311++G(d,p) level of theory. The first order hyperpolarizability ( 0) and related properties (β, α0, Δα) of F2CNH were calculated. Besides, FMOs, MEP, Mulliken atomic charges and various thermodynamic parameters such as zero-point energy, rotational constants and entropy were also calculated.


Introduction
Furan ring as an important group of heteroaromatic compounds that have been found in many natural products and substances that have useful in industrial applications [1].It is often used as synthetic intermediates in the preparation of acyclic, carbocyclic, and heterocyclic compounds [2] and its derivatives as well as some other heterocyclic compounds are of great interest due to their application of molecules to characterise the active sites in zeolites [3,4].Furan is a heterocyclic organic compound consisting of a five member ring with one oxygen and four carbon atoms.
Furan is a colorless, flammable, highly volatile liquid with a boiling point close to room temperature.Furan is found in heat-treated commercial foods and it is produced through thermal degradation of natural food constituents [5,6].Notably, it can be found in roasted coffee, instant coffee, and processed baby foods [7,8].
Exposure to furan at doses about 2000 times the projected level of human exposure from foods increases the risk of hepatocellular tumors in rats and mice and bile duct tumors in rats [9] and thus furan is therefore listed as a possible human carcinogen [9].
The hydrazone derivatives in the organic molecule bring several physical and chemical properties.
The hydrazones are bearing the >C=N-N< which leads the molecule towards nucleophilic and electrophilic nature.The ability of hydrazones to react with both electrophilic and nucleophilic reagents widens their application in organic chemistry and designing the new drugs [10][11][12].Several hydrazone derivatives have been reported as insecticides, nematocides, herbicides, rodenticides and antituburculosis in addition to that some of the hydrazone were found to be active against leukemia, sarcoma and illnesses [10,13].
According to our knowledge, neither the quantum mechanical calculations nor the vibrational spectra of the title molecule F2CNH have been reported so for.Hence the present study, we aim to interpret the vibrational spectra of F2CNH molecule by applying the ab initio/DFT computations to derive information about vibrational frequencies, IR, Raman intensities, electronic transitions and intra-molecular charge transfer, etc.

Computational Details
The entire calculations were performed at DFT levels on a Pentium 1V/3.02GHz personal computer using Gaussian 03W [17] program package, invoking gradient geometry optimization [17,18].In this study, the DFT/B3LYP/6-311++G(d,p)) level of basis set was used for the computation of molecular structure, vibrational frequencies and energies of optimized structures.The vibrational modes were assigned on the basis of TED analysis using VEDA4 program [19].
It should be noted that Gaussian 03W package able to calculate the Raman activity.The Raman activities were transformed into Raman intensities using Raint program [20] by the expression: ( Where Ii is the Raman intensity, RAi is the Raman scattering activities, νi is the wavenumber of the normal modes and ν0 denotes the wavenumber of the excitation laser [21].The same formula (Eqn. 1) has

Molecular geometry
The optimized bond parameters of F2CNH was carried out using DFT/B3LYP/ 6-311++G(d,p) basis set and are listed in Table 1.The optimized structure is shown in  with XRD values and also find support from the literature values of related structure [24,25].

Vibrational analysis
The fundamental vibrations of a non-linear molecule which contains N atoms is equal to (3N-6), apart from three translational and three rotational degrees of freedom [26,27] 2. The vibrational assignments were made by visual inspection of modes animated by using the Gauss view [17] program and are also justified with the help of TED analysis.The combined vibrational spectra of F2CNH are shown in Figs. 2 and 3.

C-H Vibrations
The heteroaromatic molecule shows the presence of C-H stretching mode in the region 3100-3000 cm -1 which is the characteristic region for the ready identification of C-H stretching [28,29].In this molecule, nine C-H stretching vibrations are expected to occur in which, four from pyridin ring, three from furan ring and one from hydrazone linkage.The pyridin ring C-H stretching vibrations observed at 3069 (m) in FT-IR whereas FT-Raman shown at 3071 and 2986cm -1 which is moderately in line with our earlier study [16].The calculated wavenumbers for the same mode lies at 3076, 3061, 3032 and 3016 cm -1 (mode nos: 5-8).The experimental C-H stretching modes corresponding to furan ring are assigned to 3120 cm -1 /FT-IR and 3117 cm -1 in FT-Raman and their harmonic value lies at 3151, 3135 and 3119 cm -1 (mode nos: 2-4).The C-H stretching in hydrazone linkage is calculated at 2919 cm - 1 and its corresponding experimental value at 2926 cm -1 in FTIR spectrum (mode no: 9) which is close to the value of literature [16] .Furthermore, these assignments are in good agreement with literature [28][29][30] and also find support from TED value [≥ 85%].

C=O, C-O Vibrations
The C=O stretching band is characterized by a sharp intense band appearing in between 1680 and 1715 cm -1 [35,36].According to this, the sharp intense bands in FTIR: 1682/FT-Raman: 1673 cm -1 spectra are assigned to C 14 =O 15 stretching mode, were as in our previous study [16] values shown at 1661/1663 in FT-IR/FT Raman respectively which is also confirmed by literature [14] and also find support from harmonic value: 1689 cm -1 (mode no: 10).The βC 14 =O 15 mode is assigned at 881 cm -1 (mode no: 40) in comparison with literature [14].In our study, the bands observed at 878 and 882 cm -1 are due to β C=O mode in FTIR and FT-Raman spectra, respectively.The calculated TED (40%) corresponding to this mode shows that this mode is not a pure mode but contaminated with β CNN and β COC modes as shown in Table 2.The mode no: 47 (710 cm -

1
) having TED value (45%) is attributed to Γ C=O mode, which is in agreement with the observed FTIR bands at 705 cm -1 .These C=O deformations vibrations are well supported by literature [14].
According to Ramesh Babu et al., (2014) [14], the harmonic frequencies of C-O stretching in furan ring appear in the range 1193-905 cm -1 .The frequency of the νO 1 -C 5 and νO 1 -C 2 vibrations are calculated to be 1170 and 1067 cm -1 , respectively for F2CNH and these modes are observed in the FT-Raman spectrum at 1158 and 1062 cm -1 (FTIR: 1062 cm -1 ) with weak intensity.
These assignments are well within the expected range and they have considerable TED values (31% and 43%).The β COC (mode nos: 37, 45) and τ COC (mode nos: 59, 64) vibrations are presented in Table 2.These assignments are also supported by the literature [33] in addition to TED output.

C=N, C-N and N-N vibrations
The IR and Raman bands observed between 1443 and 1227 cm -1 in pyridine derivatives have been assigned to ν C-N vibrations [37].(mode no: 67) and 31 cm -1 (mode no: 69) respectively.
These assignments are having considerable TED values.

N-H Vibrations
The N-H stretching vibrations occur in the region 3400-3200 cm -1 [38] and Ramesh babu et.al., [14] observed at 3246 cm -1 in FTIR spectrum.In agreement with these observation, in the present case also this band at 3367 cm -1 (mode no: 1) is assigned to stretching frequency of N-H group.This assignment is straight forward on the basis of their calculated TED value (100 %).The calculated wavenumber for β N-H (1495 cm -1 /mode no: 15) and Γ N-H (523 cm -1 / mode no: 53) modes well reproduced the experimental ones in FT-Raman (1475 cm -1 ) and FTIR (521 cm -1 ) spectra, respectively.These assignments are made in accordance with the literature [14] and also find support from their respective TED values (58% and 30%).

C=C, C-C Vibrations
In furan derivatives, medium to strong bands have appeared in the regions of 1390-1400, 1470-1520, 1560-1610 cm -1 , which are due to the C=C ring stretching vibrations [27].In general, furan with electronegative substituent has strong bands in these regions.Usually Five membered ring compounds with two doublet bond in ring, shows three ring stretching bands near 1400, 1490 and 1590 cm -1 [39].
In our present study, the C=C stretching bands observed at 1469 (m), 1428 (m), and 1337 cm -1 (s) in FT-IR spectrum, whereas FT-Raman band observed at 1426 as weak band.On the other hand, ν c=c bands were predicted at 1449, 1443 and 1315 cm -1 (mode nos: 16, 17 and 20) and in good agreement with literature [14].
The mode nos: 41, 45 and 50, 52 are belong to β CCC and Γ CCC modes, respectively.In which mode nos: 45 (759 cm -1 ) and 52 (581 cm -1 ) are justified by the observed FTIR bands at 756 and 582 cm -1 and also find support from TED value.
The C-C stretching was assigned in the region 1668-1218 cm -1 for some substituted pyridines [37].
Ramesh Babu et al., [40]  These assignments find support from literature [40] in addition to TED output.Further, the mode no: 56 is further supported by observed band (FTIR/419 cm -1 ).

NLO Property
The molecular electronic dipole moment and

NBO analysis
The NBO analysis has been carried out with B3LYP/6-311++G(d,p) level of basis set.The Lewis and non-Lewis NBO's of the F2CNH are given in Table 4.The

HOMO-LUMO analysis
The HOMO and LUMO are the main orbital's that take part in chemical stability.The HOMO represents the ability to donate an electron, whereas the LUMO is an electron acceptor which represents the ability to obtain an electron.This also predicted that the nature of electrophiles and nucleophiles to an atom where the HOMO and LUMO are stronger.The energy gap of F2CNH was calculated using B3LYP/6-311++G(d,p) level and are listed in Table 5.In the present study, the HOMO part is located over the furan ring and hydrazone linkage and HOMO energy is calculated about -6.032 eV.
Similarly, the LUMO is located over the entire molecule and especially on pyridine ring and LUMO energy is -   6.

UV-Vis spectra analysis
The nature of the electronic transitions in the observed UV-visible spectrum of the title compound F2CNH had been studied by the TD-DFT involving configuration interaction between the singly existed electronic states.The observed UV-vis spectrum was shown in Fig. 5.The electronic transitions and the corresponding excitation energies were listed in Table7.
The calculated electronic transition is shown at 333 nm whereas, the experimental electronic transition observed at 360 nm.The difference in these two values may possibly be owing to solvent influence.

MEP analysis
The molecular electrostatic potential (MEP) map was calculated using B3LYP/6-311++G(d,p) level of basis set.The 3D plot of MEP map of F2CNH is shown in

Thermodynamic properties
The various thermodynamic parameters such as: total energies, zero-point energy etc were calculated using B3LYP/6-311++G(d,p) basis set are presented in Table 9.On the basis of vibrational analysis, the statistical thermodynamic functions heat capacity (C 0 p,m ) entropy (S 0 m ), and enthalpy changes (ΔH 0 m ) for the F2CNH were obtained from the theoretical harmonic frequencies listed in Table 10.It can be seen from Table 10, the thermodynamic functions are increasing with All the given thermodynamic data are the helpful information for further study on F2CNH.They can be used to compute the other thermodynamic energies according to relationships of thermodynamic functions and estimate directions of chemical reactions according to the second law of thermodynamics in thermochemical field [43].All the thermodynamic calculations were done in gas phase and they could not be used in solution.

Conclusion
A complete vibrational analysis has been carried properties are also reported.
reported the spectral Characterization of (E)-1-(Furan-2-yl) methylene)-2-(1-phenylvinyl) hydrazine (FMPVH) were carried out by using FT-IR, FT-Raman and UV-Vis spectrometry.The geometry, electronic properties, polarizability, and hyperpolarizability of 5-nitro-2furaldehyde semicarbazone (5N2FSC) has been calculated using density functional theory (DFT) with the hybrid functional B3LYP method by Vijay Narayan et al., .org | JNDC CC-license DOI : 10.14302/issn.2377-2549.jndc-16-949Vol-1 Issue -2 Page No-3 been used to convert the Raman activity into Raman intensity.ethanolic solution of furfural (1 mL, 0.01 mol) were added to 5 mL of aqueous solution of nicotinic acid hydrazide (1.37 g, 0.01 mol) and stirred well for an hour in the presence of hydrochloric acid to form a white precipitate.The reaction mixture was maintained at room temperature and the colourless solid was obtained.The solid was separated and filtered under suction, washed with ice-cold water.The precipitate was washed with water and filtered and again washed with petroleum ether (40-60%) and dried over in a vacuum desicator then the product was recrystallized from hot ethanol.

Fig. 7 . 4 . 8
Fig. 7.In MEP map, the maximum positive/negative regions are preferred sites for nucleophilic/electrophilic attack and are represented by Blue/Red colour, respectively.The importance of MEP lies in the fact that it simultaneously displays molecular size, shape as well

Table 2
continued on the next page…..

Table 4 .
The second order perturbation theory analysis of Fock Matrix in NBO basis for F2CNH www.openaccesspub.org| JNDC CC-license DOI : 10.14302/issn.2377-2549.jndc-16-949Vol-1 Issue -2 Page No-14 molecular first hyperpolarizability of F2CNH were calculated using B3LYP level and the obtained results were given in table 3. The dipole moment was calculated

Table 5 .
The Physico-chemical properties of

Table 3 .
The NLO measurements of F2CNH

Table 6 .
The frontier molecular orbital of F2CNH

Table 8 .
The Mulliken atomic charges of F2CNH

Table 10 .
Thermodynamic Properties at different temperatures