Accepted Manuscript Normal coordinate analysis and Vibrational spectroscopy (FT-IR and FT-Raman) studies of 5-methyl-N-[4-(trifluoromethyl) phenyl]-isoxazole-4-carboxamideusing density functional method R. Shahidha, S. Muthu, E. Elamurugu Porchelvi, M. Govindarajan PII: DOI: Reference:

S1386-1425(14)00746-X http://dx.doi.org/10.1016/j.saa.2014.04.173 SAA 12137

To appear in:

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Received Date: Revised Date: Accepted Date:

9 March 2014 19 April 2014 23 April 2014

Please cite this article as: R. Shahidha, S. Muthu, E. Elamurugu Porchelvi, M. Govindarajan, Normal coordinate analysis and Vibrational spectroscopy (FT-IR and FT-Raman) studies of 5-methyl-N-[4-(trifluoromethyl) phenyl]isoxazole-4-carboxamideusing density functional method, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2014), doi: http://dx.doi.org/10.1016/j.saa.2014.04.173

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Normal coordinate analysis and Vibrational spectroscopy (FT-IR and FT-Raman) studies of 5-methyl-N-[4-(trifluoromethyl) phenyl]-isoxazole-4carboxamideusing density functional method R. Shahidhaa, S.Muthub*, E.Elamurugu Porchelvic, M. Govindarajand

a

Research and Development Centre, Bharathiar University, Coimbatore 641 046, India Department of Physics, Sri Venkateswara College of Engineering, Sriperumbudur 602 105,India c Department of Physics, Kanchi Pallavan Engineering College, Kanchipramb

631502,Tamilnadu,India d

Department of Physics, MGGA College, Mahe, India

Corresponding author, Tel.: 919443690138. Email address: [email protected] , [email protected] (Dr.S.Muthu) Abstract Vibrational

spectral

analysis

of

5-methyl-N-[4-(trifluoromethyl)

phenyl]-isoxazole-4-

carboxamideis (5MN4TPI4C) moleculewas carried out using FT-IR and FT-Raman spectroscopic techniques. The equilibrium geometry, harmonic vibrational wavenumbers, various bonding features have been computed using density functional B3LYP method with 6311G (d,p) as basis set. The assignments of the vibrational spectra have been carried out with the aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFFM). Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.The NonLinear Optical (NLO) behavior of 5MN4TPI4C has been studied by determination of the electric dipole moment (μ) and hyperpolarizability (β)by using B3LYP/6-311G(d,p) method. The molecular orbital compositions and their contributions to the chemical bonding are studied by Total density of energy states (TDOS), sum of α and β electron (αβDOS) density of

states.Thermodynamic properties (heat capacity, entropy and enthalpy) of the title compound at different temperatures are calculated. INTRODUCTION 5-methyl-N-[4-(trifluoromethyl) phenyl]-isoxazole-4-carboxamideis an isoxazole containing heterocyclic compound recently approved for the treatment of active rheumatoid arthritis in the USA. [1]. 5-methyl-N-[4-(trifluoromethyl) phenyl]-isoxazole-4-carboxamide is used to treat the symptoms of rheumatoid arthritis. Being prod rug upon absorption 5-methyl-N-[4(trifluoromethyl) phenyl]-isoxazole-4-carboxamidequickly converts into ring opened isomer mononitrilamide [2-4] as the active therapeutic agent, which in turn confers immune modulating activity through the dual mechanisms of selective inhibition of dihydroorotate dehydrogenase [5] and tyrosine kinase [6] and thus suppresses the T cell proliferation.Heterocyclic compounds

are commonly used as scaffolds on which pharmacophores are arranged to provide potent and selective medicines or pesticides[7-9].5MN4TPI4C is clinically efficacious, but nevertheless is not free from adverse effects. Its sluggish clearance, caused by the very long plasma life and severe liver function impairment has resulted in unusual dose regimens or drug monitoring protocols. These clinical difficulties have prompted intensive efforts to investigate 5MN4TPI4Canalogues, mainly by structural optimization in the phenyl ring, as novel, potent immune modulating agents with fewer and lesser severe adverse effects. The drug product was designed as a stable immediate- release film coated tablet. 5MN4TPI4C is available for oral administration as tablets containing 10, 20 and 100mg of active drug. In the present study FT-IR, FT-Raman spectral investigation oftitle compound has been performed using Density Functional Theory(DFT). A complete vibrational analysis of the molecule was performedby combining the experimental and theoretical information using Pulay‟s DFT based scaled quantum

mechanical(SQM) approach. The change in electron density (ED) in the *and * anti bonding orbital‟s and stabilization energies E(2) havebeen calculated by NBO analysis to acquire clear evidence of stabilizationoriginating in the hyper conjugation of hydrogen-bondedinteraction. The linear polarizability () and the first order hyperpolarizability(βtot) values of the investigated molecule have been computedusing DFT calculations. In addition, HOMO, LUMO analysishas been used to elucidate the information regarding charge transferwithin the molecule. By analyzing the total (TDOS) and (αβDOS), the molecular orbital composition and their contributions to the chemical bonding are studied. Keywords:DFT; FTIR and FT- Raman spectra; NCA; NBO Experimental details The compound under investigation namely 5MN4TPI4Cis purchased from M/S Aldrich chemicals,(USA) with spectroscopic grade and it is used as such without any further purification. The FT-IR spectrum of the sample is recorded in the region 4000-500cm-1 in evacuation mode using KBr pellet technique with 1.0cm-1 resolution on a PERKIN ELMER FT-IR spectrophotometer and FT-Raman spectrum of the molecule is recorded in the region 4000-400 cm-1 in pure mode using Nd:YAG laser of 150mw on a BRUKER RFS 100/s at SAIF, IIT Chennai. Computational Detail The quantum chemical calculations have been performed at DFT/B3LYP method using 6-311G (d,p) basis set using the Gaussian 03W program [10] package, invoking gradient geometry optimization [11].In order to improve the calculated values in agreement with the experimental values, it is necessary to scale down the calculated harmonic frequencies. Hence, the vibrational

frequencies calculated at the range of wave number above 1700cm-1 are scaled as0.958cm-1 and below 1700cm-1scaled as 0.983cm-1for B3LYP/6-311G(d,p)[12].Normal coordinate analysis has been performed to obtain full description of the molecular motion pertaining to the normal modes with MOLVIB program version 7.0 written by Sundius [13]. Natural co-ordinate as suggested by Pulay et al [14,15] has been written as input for the MOLVIB program. The natural bonding orbital (NBO) calculations [16] were performed using NBO 3.1 program as implemented in the Gaussian 03W package at the above said level in order to understand various second order interaction between the filled orbital of one subsystem and vacant orbital of another subsystem, which is measure of the intermolecular and intra molecular delocalization or hyper conjugation. The first hyper polarizabilities and related properties (βtot α, Δα) of title compound 5MN4TPI4C were calculated usingB3LYP/ 6-311G (d, p) basis set. Result and discussion Optimization of the geometric parameters The numbering system adopted in the molecular structure of 5MN4TPI4C is shown in Fig.1. The most optimized structural parameters of 5MN4TPI4C are calculated by B3LYP level with 6311G(d,p) basis set and presented in Table 1. The calculated N-C bond lengths of the ring vary from 1.301 to 1.412A and the calculated bond length for C-C varies from 1.372 to 1.502A. The bond length for C-H, N-H, C-O,C-F and O-H are found to be 1.08,1.01,1.218,1.35 and 2.364A,respectively. Several researchers have explained the changes in the frequency or bond length of the C-H bond on substitution due to a change in the charge distribution on the carbon atom of the benzene ring. The bond lengths obtained from B3LYP method using 6-311G (d,p) basis set well fit the experimental data[17]. Vibrational analysis

The vibrational spectral assignments have been carried out with the assist of NCA. The internal co-ordinate for 5MN4TPI4C were defined as given in Table S1 (supplementary material) and are summarized in Table S2 according to Pulay‟s recommendations. The calculated wave numbers related to the observed peaks are shown in Table 2 along with detailed assignments. The observed FTIR and Raman spectra and simulated theoretical spectra refined by SQM procedure implemented at B3LYP with 6-311G (d,p) basis set are given in Figs. 2 and 3 for visual comparison. CF3 group vibrations: In the vibration spectra of the bands found over a wide frequency range 1360-1000cm-1 may due to C-F stretching vibrations [18]. For the assignments of CF3 group frequencies, nine fundamental vibrations can be associated to each CF3 group. Three stretching, three bending, two rocking modes and a single torsional mode describe the motion of the CF3 group. The CF3asymmetric stretching frequencies are established at 1200cm-1 in FTIR and CF3 stretching frequencies is observed at 1125 cm-1 in FT-Raman spectrum. We have observed the CF3 in plane bending mode of 500cm-1, FTIR and 520cm-1 in Raman spectrum and CF3 symmetric bending mode at 474cm-1 in the Raman spectrum. These vibrational modes are also confirmed by their PED values. The CF3 deformation modes mainly coupled with in-plane bending vibrations. The bands obtained at 400cm-1 and 139cm-1 in Raman are assigned to CF3 in-plane and out-of-plane rocking modes, respectively. In accordance with the theoretical calculations, the weak Raman band located at 80cm-1 can be assigned to the out-of-plane bending vibrations fo the CF3 group. In the FTIR and Raman spectra, no experimental band available below 50cm-1. However, we have reported the calculated vibrational wave numbers in this region for 5MN4TPI4C in Table

2.The weak and ill-defined low frequency bands located at 16cm-1 was tentatively assigned to the CF3tortional mode. CH3 group vibrations: The title molecule possesses one methyl groups attached to carbon atom. For the assignments of CH3 group frequencies, basically nine fundamentals could be associated to each CH3group [19]. In this case, the asymmetric methyl stretching bands are observed at 3100cm -1 and 3050cm-1 in IR and Raman spectra respectively. One Raman band identified at 3000cm -1 which is assigned for symmetric methyl stretching. Methyl symmetric and asymmetric deformation vibrations are expected in the region 1380-1370cm-1 and 1470-1440cm-1[20] The symmetric deformation is observed at 1328cm-1 and 1322cm-1 in IR and Raman spectra respectively. One Raman band is observed at 1412cm-1 for asymmetric deformation. Methyl rocking generally appears as a weak, moderate or sometimes strong band in the region 1050±30cm-1 and 975±45cm-1[21], which is observed at 975cm-1 in Raman spectra. CH3 in plane and out of plane bending vibrations were assigned within the characteristic region and reported in Table 2. C-H vibrations: The hetero aromatic structure show the presence of C-H stretching vibrations in the region 31003000cm-1[22-24]. This is the characteristic region for the ready identification of C-H stretching vibrations. They are not appreciably affected by the nature of the substituent. In the present work, the bands observed at 3100, 3080, 3050, 3025cm-1 in FTIR and 3150,3120,3100cm-1 in FT-Raman. The C-H in plane bending and C-H out-of-plane bending vibrations are normally found in the range 1000-1300cm-1 and750-1000cm-1 respectively in the aromatic compounds [25,26]. The substitution sensitive C-H in-plane bending vibrations are normally found at 1110

and 1055cm-1 in FTIR and 1181, 1130cm-1 in FT-Raman spectrum. The IR bands observed at 915,899,753cm-1 and Raman bands observed at 910,775,756cm-1 are assigned for C-H out-ofplane bending vibration. The bending ring CH vibrations are expected within the range are reported in Table 2. They show good agreement with the theoretically computed values with the maximum contribution of PED. The ring deformation modes have also been observed. CC and CN vibrations: The carbon-carbon stretching modes of the phenyl group are expected in the range from 16501200cm-1. The actual position of these modes is determined not so much by the nature of the substituent‟s but by the form of substitution around the ring [27]. In the present case, the C-C stretching vibration are found at 1692,1608,1541,1525,1475,1300,1160cm-1 in FTIR and at 1691,1605,1533,1520,1460,1250cm-1 in FT-Raman spectrum. The bands are identified at 1055,950cm-1 FT-Raman 960,945cm-1in FT-Raman spectra assigned for C-C-C n-plane bending. The C-N stretching frequency is very difficult task since it falls in complicated region of the vibrational spectrum, is., mixing of several bands are possible in this region assigned C-N stretching absorption in the region 1386-1266cm-1 for aromatic amines [24]. In this present work, the C-N stretching vibration observed 1261cm-1 in FTIR and at 1350, 1262, 1250cm-1 in FTRaman spectrum. The computed frequencies at 626,389,332cm-1 are assigned as CN out-of-plane bending and these vibrations contribute more than 40% to the PED. Natural bond orbital (NBO) analysis NBO analysis provides a possible, „natural Lewis structure‟ pictureof ø, because all orbital details are mathematically chosen toinclude the highest possible percentage of the electron density. Auseful aspect of the NBO method is that it gives information aboutinteractions in both filled and virtual orbital spaces that could enhancethe analysis of intra-and intermolecular

interactions. The second order Fock matrix was carried out to evaluate the donor–acceptor interactions in the NBO analysis [28]. The interactions resultis a loss of occupancy from the localized NBO of the idealizedLewis structure into an empty non-Lewis orbital. For each donor (i)and acceptor (j), the stabilization energy E(2) associated with thedelocalization i j is estimated as E(2) = Eij = qi where qi is the donor orbital occupancy, are i and j diagonal elementsand F(i,j) is the off diagonal NBO Fock matrix element. Naturalbond orbital analysis provides an efficient method for studyingintra and intermolecular bonding and interaction among bonds, and also provides a convenient basis for investigating charge transferor conjugative interaction in molecular systems. Some electrondonor orbital, acceptor orbital and the interacting stabilization energyresulted from the second-order micro-disturbance theory arereported [29]. The larger the E(2) value, the more intensive is theinteraction between electron donors and electron acceptors, i.e.the more donating tendency from electron donors to electronacceptors and the greater the extent of conjugation of the wholesystem. Delocalization of electron density between occupied Lewis Type (bond or lone pair) NBO orbitals and formally unoccupied(antibond or Rydgberg) nonLewis NBO orbitals correspond to astabilizing donor–acceptor interaction. NBO analysis has been performedon the molecule at the DFT/B3LYP/6-31G (d,p) level in order to elucidate the conjugation, hyperconjugation and delocalization of electron density within the molecule. The intra molecular interactionis formed by the orbital overlap between (and (C–C, C–H, C-F and C–N) and * and *(C–C, C–H, C-F and C–N)) bond orbital whichresults intra molecular charge transfer (ICT) causing stabilization ofthe system. These interactions are observed as increase in electrondensity (ED) in C–C anti bonding orbital that weakens the respectivebonds [30]. The

electron density of conjugated double as wellas single bond of the aromatic ring (1.9e) clearly demonstratesstrong

delocalization

inside

the

molecule.

The

strong

intramolecular

hyperconjugation interaction of the (C–C) to the  (C–C) bond in the ring leads to stabilization ofsome part of the ring as evident from Table 3. For example, the intra molecular hyper conjugative interaction of  (C1-C2) distribute to * (C2-C3), * (C3-C7) leading to stabilization of 7.32KJ/mol. In the case of  (C2-C3) interacting with * (C1-C2, C1-H5,C3-C7) leading to stabilization of 3.53KJ/mol. The same further conjugate with antibonding orbital of * (C1-N4, C11-O12) which leads to strong delocalization of 26.63 KJ/mol. The magnitude of charges transferred from (LP(1)N4)

(C1-C2,C3-O6) and (LP(1)N13)

(C11-O12,C15-C17) show that

stabilization energy of about  4.5KJ/mol and 3KJ/mol respectively. NBO analysis also revealed that interaction energy in this molecule donates an electron from O6LP (2) to the * (C2-C3) which leads to the strongest stabilization of 36.99KJ/mol. Nonlinear optical effects Hyperpolarizabilities are very sensitive to the basis sets and level of theoretical approach employed [31-33], that the electron correlation can change the value of hyperpolarizability. Urea is one of the prototypical molecules used in the study of the non-linear optical (NLO) properties of molecular systems. Therefore it has been used frequently as a threshold value for comparative purposes. The calculations of the total molecular dipole moment(µD), linear polarizability(α) and first-order hyperpolarizability(βtot) from the Gaussian output have been explained in detailed previously[34] and DFT has been extensively used an effective method to investigate the organic NLO material [35]. The polar properties of the title compound were calculated by Density Functional Theory (DFT) using B3LYP method with 6-311G (d,p) basis sets using Gaussian 03W program package. Urea is one of the prototypical molecules used in the study of

the NLO properties of the molecular systems. Therefore it was used frequently as a threshold value for comparative purposes. The calculated values of βtot for the title compound is 1.7157X10-30 cm5/esu shown in Table S3, which are greater than those of urea (β of urea is 6.0690X10-31cm5/esu obtained by DFT (B3LYP)/6-311G (d,p) method). Since the values of the first hyperpolarizability tensors of the output file of Gaussian 03W are reported in atomic units(a.u), the calculated values were converted into electrostatic units (1 a.u = 8.6393X10-33esu). Theoretically, the first hyperpolarizability of the title compound is 2.83 times magnitude of urea. Our title molecule with greater dipole moment and hyperpolarizability value than urea shows that the molecule has large NLO optical property. HOMO-LUMO energy Many organic molecules that containing conjugated π electrons are characterized hyperpolarizabilities and were analyzed by means of vibrational spectroscopy [36,37] in most cases even in absence of inversion symmetry, the strongest bands in the Raman spectrum is weak in the IR spectrum and vice versa. But the interamolecular charge transfer from the donor to accepter group through a single-double bond conjugated path can induce large vibration of both the molecular dipole moment and the molecular polariazability, making IR and Raman activity strong at the same time the experimental spectroscopic behavior described above is well accounted for by abinitio calculations in π conjugated systems that predict exceptionally large Raman and Infrared intensities for the same normal modes. It is also observed in our title molecule the bands in FT-IR spectrum have their counterparts in Raman shows that the relative intensities in IR and Raman spectra are comparable resulting from the electron cloud movement through π conjugated frame work from electron donor to electron acceptor groups. Highest occupy molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are very

important parameters for quantum chemistry. We can determine the wave the molecule interacts with other species hence; they are called the frontier orbitals. HOMO, which can be thought the outer most orbital containing electrons, tends to give these electrons such as an electron donor. On the other hand LUMO can be thought theinter most orbital containing free places to accept electrons [38]. Owing to the interaction between HOMO and LUMO orbital of a structure, transition state transition of π-π*type is observed with regard tothe molecular orbital theory [39]. Therefore, while the energy of the HOMO is directly related to the ionization potential, LUMO energy is directly related to the electron affinity. Energy difference between HOMO and LUMO orbital is called as energy gap that is an important stability for structure [40]. The atomic orbital compositions of the frontier molecular orbital are sketched in Fig.4. HOMO energy = -0.3461 a.u LUMO energy = -0.2027 a.u HOMO-LUMO energy gap = -0.1434 a.u Molecular electrostatic potential analysis Electrostatic potential maps, also known as electrostatic potential energy maps, or molecular electrical potential surfaces, illustrate the charge distributions of molecules three dimensionally. The purpose of finding the electrostatic potential is to find the reactive site of a molecule. These maps allow us to visualize variably charged regions of a molecule. Knowledge of the charge distributions can be used to determine how molecules interact with one another. Molecular electrostatic potential (MESP) mapping is very useful in the investigation of the molecular structure with its physiochemical property relationships [41-43]. Total Self Consistent Field(SCF) electron densitySurface mapped with molecular electrostatic potential (MESP) of

5MN4TPI4C are shown in Fig.5. The molecular electrostatic potential surface MESP which is a 3D plotof electrostatic potential mapped onto the iso-electron density surface simultaneously displays molecular shape, size and electrostatic potential values. The color scheme for the MESP surface is red-electron rich or partially negative charge; blue-electron deficient or partially positive charge; light blue-slightly electron deficient region; yellow-slightly electron rich region, respectively. Areas of low potential, red are characterized by an abundance of electrons. Areas of high potential, blue are characterized by a relative absence of electrons. Oxygen has a higher electro negativity value would consequently have a higher electron density around them. The MESP of 5MN4TPI4C clearly indicates the electron rich centers of Nitrogen and Oxygen atoms. The MESP map shows that the negative potential sites are on electronegative atoms as well as the positive potential sites are around the hydrogen atoms.These sites give information about the region from where the compound can have non-covalent interactions. According to these calculatedresults, the MEP shows that the negative potential sites are on oxygen, Nitrogen atoms and the positive potential sites are around the hydrogen atoms. These sites give information about the region from where the compound can have intermolecular interactions. Total, sum of alpha plus beta electrons DOS In the boundary region, neighboring orbitals may show quasi degenerate energy levels. In such cases consideration of only the HOMO and LUMO may not yield a realistic description of frontier orbitals. For this reason, the total (TDOS), sum of α and β electron density of states[44,45], in terms of Mulliken population analysis were calculated and created by convoluting the molecular orbital information with Gaussian curves of unit height and full width at half maximum(FWHM) of 0.3 eV by using the GaussSum 2.2 program[46]. The TDOS, αβ DOS of 5MN4TPI4Care plotted in Figs. 6-7. They provide a pictorial representation of MO

(molecule orbital) compositions and their contributions to the chemical bonding. The most important application of the DOS plots is to demonstrate MO compositions and their contributions to the chemical bonding through the positive and negative charges provide αβDOS, TDOS diagrams. The αβDOS shows the bonding, sum of positive and negative electron with nature of the interaction of two orbitals, atoms or groups. In this case, the title molecule consists of 69 α-electrons and 69 β-electrons, totally 138 electrons are occupied in density of states. The way designate a pictorial representation for cations and anions is essentially similar to that for neutral atoms in their ground state. Because of the short range of absorption, alphas are not, in general, dangerous to life unless the source is ingested or inhaled, in which case they become extremely dangerous [47]. A positive value of the αβDOS indicates a bonding interaction, negative value means that there is an anti-bonding interaction and zero value indicates nonbonding interactions [48]. Thermodynamic properties The variation in Zero- Point Vibrational Energies (ZPVEs) seems to be significant. The values of some thermodynamic parameters(such as zero point thermal energy specific heat capacity, rotational constant, entropy and dipole moment) of 5MN4TPI4Cat 298.15 K in ground state are listed in Table S4. The values of ZPVE of5MN4TPI4Cis-1022.42a.u obtained at B3LYP/6311G(d,p) method. On the basis of vibrational analysis and statistical thermodynamics, the standard thermodynamic functions heat capacity(C) entropy (S) and enthalpy changes (ΔH) for the title molecule where calculated using perl script THERMO.PL [49] and are listed in Table 4. As observed from Table 4.The values of Cp, Sm and ΔH all increase of temperature from 100 to 1000 K, which is attributed to the enhancement of the molecular vibration as the temperature increase. The correlation equations between heat capacity, entropy, enthalpy changes and

temperatures were fitted by quadratic formulas, and the corresponding fitting factors (R2) for these thermodynamic properties are 0.957, 0.992 and 0.979 respectively. The corresponding fitting equations are as follows and the correlation graphics of those shown in Fig.8. Cp = 119.2 + 0. 470T - 0.000T2 ×10-4 (R2 =0.957) Sm = 335.7+0.756T - 0.000T2×10-4 (R2 =0.992) ΔH= -66.33+0.394T + 0.000×10-4T2 (R2 =0.979) All the thermodynamic data supply helpful information for the further study on the5MN4TPI4C. They can be used to compute the other thermodynamic energies according to relationships of thermodynamic functions and estimate directions of chemicals reactions according to the second law of thermodynamics in thermo chemical field [50]. Notice: all thermodynamic calculations were done in gas phase and they could not be used in solutions. Conclusion A complete structural analysis of 5MN4TPI4C has been performed based on SQM force field obtained by DFT calculations at B3LYP/6-311G(d,p) level. Detailed interpretation of the normal modes has been made on the basis of PED calculations. The difference in HOMO and LUMO energy supports the charge transfer interaction within the molecule. To predict the reactive sites for electrophilic and nucleophilic attack for the 5MN4TPI4C molecule, the MEP at the B3LYP/6-311G(d.p) optimized geometry was calculated. The correlations between the statistical thermodynamical and temperature are also obtained. It was seen that the heat capacities, entropies and enthalpies increase with the increasing temperature owing to the intensities of the molecular vibrations increase with increasing temperature.

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Figure Captions: Fig.1: Optimized molecular structure of 5MN4TPI4C. Fig.2: Comparative representation of FT-IR spectra of 5MN4TPI4C. Fig.3: Comparative representation of FT-Raman spectra of 5MN4TPI4C. Fig.4: The atomic orbital of the frontier molecular orbital for 5MN4TPI4C. Fig.5: Molecular electrostatic potential map calculated at B3LYP/6-311G (d,p) method. Fig.6: The calculated TDOS diagram of 5MN4TPI4C. Fig.7: The sum of alpha plus beta electron DOS diagram of5MN4TPI4C. Fig.8: Correlation graphs of thermodynamic properties at different temperature of 5MN4TPI4C. .

Fig.1. Optimized molecular structure of 5MN4TPI4C.

Fig.2. Comparative representation of FT-IR spectra of 5MN4TPI4C.

Fig.3. Comparative representation of FT-Raman spectra of 5MN4TPI4C.

Fig.4.The atomic orbital of the frontier molecular orbital for 5MN4TPI4C.

Fig.5. Molecular electrostatic potential map calculated at B3LYP/6-311G (d,p) method.

Fig. 6.The calculated TDOS diagram of 5MN4TPI4C.

Fig.7.The sum of alpha plus beta electron DOS diagram of 5MN4TPI4C.

Fig.8. Correlation graphs of thermodynamic properties at different temperature of 5MN4TPI4C.

Table 1

Optimized parameters for 5MN4TPI4C (bond length (A ) bond angle (◦) Parameters

Experimental*

B3LYP/6311G(d,p)

Parameters

Experimental*

1.316 1.26 1.1 1.33 1.49 1.23 1.497 1.31 1.1 1.1 1.1 1.21 1.266 1.05 1.462 1.42 1.42 1.42 1.1 1.42 1.1 1.42 1.1 1.42 1.1 1.42 1.392 1.392 1.392 2.014

1.428 1.301 1.08 1.372 1.478 1.342 1.487 1.406 1.091 1.089 1.094 1.218 1.391 1.013 1.412 1.402 1.4 1.387 1.084 1.39 1.081 1.396 1.083 1.393 1.082 1.502 1.352 1.354 1.35 2.364

104 109 109 109 109 109 109 120

120 120 109 120 120 104 120 109 129 120 123 120

112.5 127.5 103.5 123.6 119.9 104.9 122.4 109.1 131 120.8 119.4 116.2

C3-O6-N4 C3-C7-H8 C3-C7-H9 C3-C7-H10 H8-C7-H9 H8-C7-H10 H9-C7-H10 O12-C11-N13 C11-O12-H14 C11-N13-H14 C11-N13-C15 H14-N13-C15 N13-H14-O12 N13-C15-C16 N13-C15-C17 C16-C15-C17 C15-C16-C18 C15-C16-H19 C15-C17-C20 C15-C17-H21 C16-C18-H19 C16-C18-C22 C16-C18-H23 C20-C17-H21 C17-C20-C22 C17-C20-H24 C22-C18-H23 C18-C22-C20 C18-C22-C25 C22-C20-H24 C20-C22-C25 C22-C25-F26 C22-C25-F27 C22-C25-F28 F26-C25-F27 F26-C25-F28 F27-C25-F28

B3LYP/6311G(d,p)

Bond length C1-C2 C1-N4 C1-H5 C2-C3 C2-C11 C3-O6 C3-C7 N4-O6 C7-H8 C7-H9 C7-H10 C11-O12 C11-N13 N13-H14 N13-C15 C15-C16 C15-C17 C16-C18 C16-H19 C17-C20 C17-H21 C18-C22 C18-H23 C20-C22 C20-H24 C22-C25 C25-F26 C25-F27 C25-F28 O12-H14 Bond Angle C2-C1-N4 C2-C1-H5 C1-C2-C3 C1-C2-C11 N4-C1-H5 C1-N4-O6 C3-C2-C11 C2-C3-O6 C2-C3-C7 C2-C11-O12 C2-C11-N13 O6-C1-C7

*Ref. (17)

109 129 120 111 120 119 120 120 120 124 124 120 120 120 120 120 120 120 120 120 120 109 109 109 109 109 109

110 109.7

110.177 108.679 109.2 108.1 108.3 119.7 57.4 110.9 131 115.6 71.6 118 122.9 119.1 120.6 119.4 120.1 120.3 120 120.1 119.9 119.6 120.5 119.6 120 119.6 119.7 119.8 120.7 111.8 111.9 112.2 106.5 107.4 106.8 119.8

Table 2 Vibrational assignments of 5MN4TPI4C by normal coordinate analysis based on SQM force field calculations.

78

Experimental wave number (cm-1) FTIR FTRaman 3450 3460

3572

3422

9

90

νNH(95)

77

3100

3150

3243

3107

0

68

νCH(90)

76

3080

3120

3215

3080

0

60

νCH(99)

75

3050

3100

3199

3065

0

80

νCH(98)

74

-

-

3199

3065

0

51

νCH(96)

73

3025

-

3175

3042

1

43

νCH(90)

72

3000

3050

3144

3012

1

26

νCH3asyms (80) + CC(15)

71

-

3000

3104

2974

1

58

CH3syms(95)

70

2900

2978

3044

2916

1

100

CH3OPS(90)

69

-

1750

1748

1718

100

48

bCCH(75)+νCC(20)

68

1692

1691

1659

1631

21

87

νCC(80)+ CH3sym(16)

67

-

1650

1636

1608

15

14

νCC(55)+CH3OPS(35)

66

1608

1605

1622

1594

3

1

νCC(72) + νCH(28)

65

1541

1533

1552

1526

10

6

νCC(95)

64

1525

1520

1525

1499

5

31

νCC(63) + CH3Opb (25)

63

-

1460

1492

1467

7

21

νCC (82)

62

-

-

1481

1456

3

7

νCC(57) + νCN (40)

61

1475

-

1478

1453

3

9

νCC(65) + CH3asymS (22)

60

1450

-

1440

1416

25

8

νCC(65) + bCCH(31)

59

1425

-

1428

1404

25

15

νCC(79) + νCC(12)

58

-

1412

1416

1392

6

5

CH3opb(58) + νCN(27)

57

-

1350

1342

1319

10

13

νCN(62) + CH3ops(30)

56

-

1325

1338

1315

3

15

CH3ipb(45) + CF3 asyms(30) + νCC

55

1328

1322

1328

1305

83

29

CH3sb (50) + bCCH(25) + νCN(15)

54

1300

-

1301

1279

58

11

νCC(80)

Mode

Theoretical wavenumber (cm-1) Unscaled

IR

b

IRAMAN

c

Assignments (%PED)

a,d

Scaled

53

1261

1262

1260

1239

8

9

νCN(64) +bCCH(11) + CF3syms (12)

52

-

1250

1245

1224

11

5

νCN(38) + CF3asyms (38)

51

1200

-

1207

1186

9

9

CF3asyms (42) + νCN(26)

50

-

1181

1177

1157

24

1

bCCH(19) + νCC(12)+CH3ipr(20)

49

1160

-

1169

1149

4

0

bCCH(49) + CF3syms (48)

48

-

1125

1139

1120

62

5

CF3syms (60) + bCCH(32)

47

-

1130

1136

1117

25

1

bCCH(51) + bCCC(20) + νCO(11)

46

1110

-

1122

1103

8

1

bCCH(39) + bCCC(15) + νCO(13)

45

-

1087

1081

1063

37

3

bCCC(46) + bCNO(20) +ωHCCC(19)

44

1055

-

1065

1047

1

0

bCCH (42) + CH3ipr(30)

43

-

1048

1029

1012

6

1

bCNO(50) + CH3 opr(34)

42

1005

1000

1003

986

2

1

CH3ipr(48) + bCCC(22)

41

-

975

985

968

0

0

CH3opr(62)+νCO(17)

40

950

960

968

952

0

0

bCCC(44)+ bCCO(15)+νCO(15)

39

-

945

955

939

3

3

bCCC(53)+ ωHCCC(21)+νCO(13)

38

915

910

917

901

3

1

ωHCCC(47)+CH3ipr(30)

37

899

-

907

892

5

9

ωHCCC(39)+τtrigd(35)

36

876

880

881

866

3

4

ωHCCN(48)+νCO(15)+bCON(12)

35

853

850

857

842

10

2

νCO(70)+bCCO(20)

34

824

-

842

828

1

1

νCO(65)+ R trigd (25)

33

800

800

791

778

9

13

R trigd (40)+ωHCCC(29)+bCON(16)

32

-

775

774

761

3

7

ωHCCC(35)+ τtrigd(20)+ CH3ipr(11)

31

753

756

748

735

1

1

ωHCCC(40)+ bCCO(20)+ bCON(13)

30

705

-

707

695

1

3

τtrigd(51)+ ωHCCC(30)

29

-

694

695

683

2

1

bCCO(49)+ bCCC(19)

28

650

-

667

656

1

1

bCNC(40)+ τCH3(15)+CF3ipb(17)

27

-

650

654

643

1

6

bCON(37)+ωNCCC(28)

26

628

632

637

626

0

1

ωNCCC(50)+CF3ops(19)

25

-

600

618

607

7

4

CF3ops(38)+Rasymd(32)

24

590

-

594

584

9

5

Rasymd(39)+ Rsymd(25)

23

570

-

575

565

2

5

Rsymd(42)+τRasymd(22)

22

-

556

563

553

5

12

τRasymd(40)+CF3ipb(15)+bCCN(12)

21

500

520

538

529

8

2

CF3ipb(35)+CFsb(45)

20

-

474

508

499

1

1

CF3sb(47)+τRsymd(21)

19

435

450

445

437

0

0

τRsymd(43)+τRasymd(34)

18

-

-

426

419

0

1

CF3ipr(50)+ωNCCC(15)+bCON(12)

17

-

400

410

403

1

1

ωNCCC(41)+ CF3sb(20)+bCCN(16)

16

-

-

396

389

2

1

ωNCCC(47)+ ωHNCC(32)

15

-

-

326

332

2

2

ωNCCC(44)+ bCNHC(24)

14

-

355

338

320

0

0

bCCN(48)+ bCNH(13)+ τCH3(11)

13

-

320

274

269

1

1

bCNH(39)+ τCH3(20)+τCF3(12)

12

-

-

266

261

0

1

ωHNCC(40)+ τCF3(17)+ τCH3(10)

11

-

250

234

230

1

1

τCH3(36)+ ωCCON(42)

10

-

255

197

194

0

0

ωCCON(48)+ CF3opr(28)

9

-

192

168

165

0

2

ωCCCC(36)+ bCCN(15)+ τOCNH(12)

8

-

-

155

152

1

1

ωCCCC(25)+ τOCNH(20)

7

-

139

117

115

0

1

CF3opr(39)+ ωHNCC(38)+ τCH3(15)

6

-

-

99

97

0

2

ωCCON(38)+CF3opb(28)

5

-

-

89

87

1

2

ωHCCN(41)+vCCN(26)+ τCH3(12)

4

-

80

50

49

0

2

CF3opb(40)+ τCH3(22)+ τCCN(19)

3

-

-

42

41

0

3

bCCN(36)+ ωCCON(19)+ bCCN(13)

2

-

-

33

32

0

1

τOCNH(31)+ τCF3(26)

1

-

-

16

16

0

0

τCF3(32)+ ωHNCCC(31)+bCNH(17)

a

Abbreviations: ν, stretching; b, in plane bending; ω, out of plane bending; τ, torsion; ipb, in plane bending; opb, out of planebending;syms, symmetric stretching; asys, asymmetric stretching; trig d, trigonal deformation; sym d, symmetric deformation; asym d, asymmetric deformation; sb, symmetric bending; ipr, in plane rocking; opr, out of plane rocking; ops,out of plane stretching. b Relative absorption intensities normalized with highest peak absorption equal to 1. c Relative Raman intensities normalized to 100. d Only PED contributions ≥10% are listed. Scaling factor: 0.958 (for wave number under 1700 cm-1) and 0.983 (for those over 1700 cm-1)for B3LYP/6-311G(d,p).

TABLE 3

Second order perturbation theory analysis of fock matrix in NBO basis. Donar(i)

Type

ED/e

Acceptor(i)

Type

ED/e

E(2)a(kjmol-1)

E(j)-E(i)b(a.u.)

F(i,j)c(a.u.)

C1-C2

σ

1.964

C2-C3

σ*

0.02915

3.03

1.27

0.055

C3-C7

σ*

0.01686

7.32

1.09

0.08

C1-N4

C1-H5

C2-C3

σ

1.99053

C2-C11

σ*

0.0639

2.54

1.31

0.052

π

1.93007

C2-C3

π*

0.29882

8.42

0.35

0.051

σ

1.9749

C1-N4

σ*

0.02528

0.68

1.11

0.025

C2-C3

σ*

0.02915

1.53

1.13

0.037

N4-O6

σ*

0.03408

4.83

0.76

0.054

C1-C2

σ*

0.02528

2.97

1.25

0.054

C1-H5

σ*

0.01481

3.53

1.17

0.057

C3-C7

σ*

0.01686

3.15

1.15

0.054

σ

π

1.77005

C1-N4

π*

0.25492

26.63

0.29

0.079

C11-O12

π*

0.25405

16.64

0.33

0.067

C7-H8

σ

1.9445

C2-C3

σ*

0.02915

4.06

1.1

0.06

C7-H9

σ

1.97954

C3-O6

σ*

0.04032

5.46

0.89

0.063

C15-C16

σ

1.97277

C15-C17

σ*

0.02618

3.91

1.26

0.031

C16-C18

σ*

0.01301

2.89

1.29

0.063

C15-C16

σ*

0.02349

3.96

1.26

0.063

C17-C20

σ*

0.0134

3

1.29

0.056

C16-C18

π*

0.01301

17.38

0.29

0.064

C20-C22

π*

0.37128

23.2

0.29

0.073

N13-C15

σ*

0.03166

3.92

1.12

0.059

C18-C22

σ*

0.0224

3.23

1.28

0.057

C22-C25

σ*

0.05547

2.86

1.08

0.05

C15-C17

π*

0.37851

21.96

0.28

0.071

C20-C22

π*

0.37128

18.09

0.29

0.065

N13-C15

σ*

0.03166

4.47

1.12

0.063

C20-C22

σ*

0.02226

3.28

1.28

0.058

C18-C22

σ*

0.0224

4.67

1.28

0.069

C15-C17

π*

0.37581

17.71

0.28

0.064

C16-C18

π*

0.30823

22.47

0.29

0.072

C15-C17

σ

π

C16-C18

σ

π

C17-C20

σ

π

N4

O6

LP(1)

LP(1)

LP(2)

N13 a

1.97481

LP(1)

1.97255

1.6387

1.97634

1.67978

1.978545

1.66885

1.95864

1.97731

1.69944

1.70212

C1-C2

σ*

0.02528

4.43

0.95

0.058

C3-O6

σ*

0.04032

4.97

0.82

0.057

C1-N4

σ*

0.00941

2.44

1.19

0.048

C2-C3

σ*

0.02915

3.3

1.21

0.056

C1-N4

π*

0.25492

14.82

0.35

0.065

C2-C3

π*

0.29882

36.99

0.36

0.103

C11-O12

σ*

0.03132

3.51

0.84

0.052

C15-C17

σ*

0.02618

2.83

0.83

0.046

E(2)means energy of hyper conjugative interaction (stabilization energy) b Energy difference donor and acceptor I and j NBO orbitals. c F(i.j) is the fork matrix element between I and j NBO orbitals.

Table 4 Thermodynamic properties at different temperatures at the B3LYP/6-311G (d,p) level for 5MN4TPI4C. T (K)

Sm (J/mol.K)

Cp (J/mol.K)

ΔH (kJ/mol)

100

77.062

20.848

1.100

150

93.047

31.629

2.924

200

109.106

42.612

5.300

250

122.767

52.108

7.862

300

136.307

60.987

11.038

350

147.643

69.910

14.338

400

157.864

77.504

17.993

450

167.678

85.034

22.352

500

175.574

91.343

26.745

Graphical abstract A complete structural analysis of 5MN4TPI4C has been performed based on SQM force field obtained by DFT calculations at B3LYP/6-311G (d,p) level. Detailed Interpretation of the normal modes has been made on the basis of PED calculations. To predict the reactive sites for electrophilic and nucleophilic attack for the 5MN4TPI4C molecule, the MEP at the B3LYP/6-311G (d.p) optimized geometry was calculated. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes.

The sum of alpha plus beta electron DOS diagram of 5MN4TPI4C.

HIGHLIGHTS  Vibrational wave numbers were computed using DFT method.  The NBO analysis explained the intramolecular hydrogen bonding.  The NLO behaviors were completed.  Hyperpolarizability and HOMO, LUMO energy were calculated.