The structural properties and vibrational frequencies of 2-phenyl-2-imidazoline have been investigated using theoretical and techniques by which a good correlation was observed. The assignments of the vibrational modes were performed with the help of normal co-ordinate analysis following the Scaled Quantum Mechanical Force Field methodology. Natural bond orbital analysis and the highest occupied molecular orbital-lowest unoccupied molecular orbital gap analysis have been carried out. UV-visible spectrum of the compound was recorded and compared with the theoretical UV-visible spectrum of the title molecule using Symmetry Adapted Cluster-Configuration Interaction method which yielded good agreement. Our results reflect that the title compound can be used as good source of UV light.
At present, there is an enormous deal of scientific attention in the field of Imidazoline derivatives. Imidazoline is a nitrogen compound and it can be utilized in organic dyes as nitrogenous electron donors since it introduces additional electron donors at position 2. Because of high molar extinction coefficient, Imidazoline and other molecular structures containing nitrogen developed as metal free organic dyes. Usually, metal-free organic dyes have the apparent molecular structure of the electron donor element and the acceptor element connected by the conjugated chain (D–π–A). 2-imidazoline is a one of the isomers derived from the imidazole. Imidazoline derivatives are pharmaceutically and biologically very significant. Imidazolines exhibit major pharmacological and biological activities such as antidepressive [
The purpose of this study is to obtain the theoretical information about the molecular structure and electronic parameters of 2-phenyl-2-imidazoline. Density functional theory has been adopted for the precise study of the molecular geometry and electronic distribution. Here we study the experimental and theoretical study of the 2-phenyl-2-imidazoline for the first time.
The powder sample of 2-phenyl-2-imidazoline (here after termed as 2PI) has been procured from sigma Aldrich chemical company (USA) with a confirmed purity greater than 98% and was utilized in the consequent spectroscopic study with no any additional purification.
Fourier transform infrared spectrum of the 2PI is recorded at the temperature 302.15˚K in the region 4000 - 400 cm−1 by Nicolet 6700 FTIR spectrometer fitted by means of a Thermo Nicolet Continuum IR microscope and through a Renishaw in via., Raman microscope with UV or visible laser excitation at a resolution of ±1 cm−1. FTIR spectrum of the given compound was recorded by KBr pellet method with Spectrum GX Fourier transform-infrared spectroscopy (FT-IR) spectrometer.
The FT-Raman spectrum of the molecule was recorded at a 4 cm−1 resolution through a Nicolet Magna 750 Raman spectrometer functioned with an InGaAs (Indium Gallium Arsenide) semiconductor detector in the 3500-0 cm−1 region. The excitation source utilized was the 1064-nm line from Neodymium: Yttrium Aluminum Garnet laser. The laser power at the sample location was typically 500 mW.
UV-Vis spectrum of the 2PI has been recorded in the region of 200 - 400 nm with a Perkin Elmer Lambda 35 UV-vis spectrometer. All the data were recorded after 1 cycle, with a period of 1 nm, slit width of 2 nm and scan rate of 240 nm・min−1 by the spectral resolution of 0.05 - 4.0 nm. The slit width was situating to 15 nm for the emission monochromator and to 10 nm for the excitation monochromator.
Quantum chemical density functional computations on 2PI were carried out using Becke’s three-parameter (B3LYP) hybrid DFT level employed to optimize the molecular geometry through the 6-31G(d, p) basis set using Gaussian 09W Revision-A.02 SMP [
The Raman activity (Si) computed by Gaussian 09W Revision-A.02 SMP version [
I i = f ( ν 0 − ν i ) 4 S i ν i ( 1 − exp ( − h c ν i k T ) ) (1)
Here ν i is the normal mode vibrational wave number; ν 0 is the exciting frequency (in cm−1 units); h, c and k are the universal constants and f is appropriately chosen common normalization factor used for all the intensities. Pure Lorentzian band shapes were employed to draw simulated FTIR and FT-Raman spectra.
The title compound 2PI has a non-planar structure with C1 symmetry, 21 atoms and therefore it has 57 normal modes of internal vibrations. The vibrational harmonic frequencies of the given molecule are computed with Density Functional Theory with Becke-3-Lee–Yang–Parr(B3LYP) method [
The theoretically calculated optimized geometrical parameters were compared with the single crystal XRD data of 2-[2-(2-Hydroxyethoxy) phenyl]-4, 4, 5, 5-tetramethyl-2-imidazoline-1-oxyl 3-oxide [
Bond length(A0)a | Bond angle(o)a | ||||
---|---|---|---|---|---|
B3LYP/6-31G(d,p) | Exp | B3LYP/6-31G(d,p) | Exp | ||
C1-N11 | 1.445 | 1.498b | N11-C1-C2 | 101.2 | 101.3b |
C1-C2 | 1.528 | 1.550b | C1-C2-N10 | 106.2 | 102.1b |
C2-N10 | 1.488 | 1.488b | C1-C2-H14 | 113.3 | - |
C3-N10 | 1.311 | 1.341b | N10-C3-N11 | 115.9 | 108.8b |
C3-N11 | 1.377 | 1.346b | C3-C4-C5 | 119.5 | 120.7b |
C3-C4 | 1.485 | 1.458b | C3-C4-C7 | 120.7 | 119.9b |
C4-C5 | 1.399 | 1. 381b | C5-C4-C7 | 119.6 | 119.4b |
C4-C7 | 1.399 | 1.391 b | C2-C1-H20 | 112.5 | - |
C7-H18 | 1.085 | 0.930b | C9-C8-C6 | 120.0 | 121.5b |
C7-C9 | 1.397 | 1.352b | C8-C6-C5 | 120.0 | 119.3b |
C9-C8 | 1.394 | 1.394b | C6-C5-C4 | 120.1 | 119.3b |
C8-C6 | 1.394 | 1.369b | C4-C7-H18 | 119.6 | 119.4b |
C6-C5 | 1.396 | 1.394b | C9-C7-H18 | 119.6 | 119.4b |
C9-H19 | 1.087 | 0.930b | C7-C9-H19 | 119.9 | 120.4b |
C8-H17 | 1.086 | 0.930b | C8-C9-H19 | 119.9 | 120.4 b |
C6-H16 | 1.086 | 0.930b | C9-C8-H17 | 120.0 | 119.2b |
C5-H15 | 1.087 | 0.930b | C6-C8-H17 | 119.9 | 119.2b |
C8-C6-H16 | 120.1 | 120.4b | |||
C5-C6-H16 | 119.8 | 120.4b | |||
N11-C3-C4 | 122.5 | 125.6b | |||
N10-C3-C4 | 121.5 | 125.5b |
be because of the intermolecular interactions during the crystalline state. Further, it is noticed that the differences are more for C-H bonds and less for the C-C and C-N bonds. The differences are of the order of 0 A˚ ± 0.156 A˚ for the Bond length when compared with the investigational data [
Both infrared and Raman spectra. A complete description of fundamental vibrational frequencies of the title molecule was given by Normal coordinate analysis. For this purpose a set of internal coordinates are defined in Supplementary Material 1. The local and non redundant symmetry coordinates are defined from these predefined internal coordinates following the recommendations of Fogarasi and Pulay [
The title molecule belongs to C1 symmetry. The 57 modes of vibrations of the molecule are distributed as 39 in plane and 18 out of plane modes. All the vibrational modes are active in:
Aromatic compounds have one or more sharp peaks of weak or medium intensity between 3100 - 3000 cm−1 [
The C-H in-plane bending vibrations of benzene and its derivatives are observed in the region 1300 - 1000 cm−1 [
The asymmetric CH2 stretching vibration is generally observed in the region 3000 - 2900 cm−1, while the CH2 symmetric stretch will appear between 2900 and 2800 cm−1 [
No.(i) | Symbola | Definitionb | Scale factors |
---|---|---|---|
Stretching | |||
1 - 8 | ν(C-C) | R1, R2, R3, R4, R5, R6, R7, R8 | 0.94293 |
9 - 12 | ν(C-N) | r9, r10, r11, r12 | 0.9461 |
13 - 17 | ν(C-H) | P13, P14, P15, P16, P17 | 0.9225 |
18 - 19 | ν(CH2ss) | (P18+P19)//2, (P20+P21)//2 | 0.9192 |
20 - 21 | ν(CH2ass) | (P18-P19)//2, (P20-P21)//2 | 0.9192 |
22 | ν(N-H) | Q22 | 0.91287 |
In-Plane bending | |||
23 | βR1tri | ( β 23 − β 24 + β 25 − β 26 + β 27 − β 28 ) / 6 | 0.96557 |
24 | βR1sym | ( − β 23 − β 24 + 2 β 25 − β 26 − β 27 + 2 β 28 ) / 12 | 0.96557 |
25 | βR1asy | ( β 23 − β 24 + β 27 − β 28 ) / 2 | 0.96557 |
26 | R2bend1 | β 29 + a ( β 30 + β 33 ) + b ( β 31 − β 32 ) | 0.956 |
27 | R2bend2 | ( a − b ) ( β 30 − β 33 ) + ( 1 − a ) ( β 31 + β 32 ) | 0.956 |
28 - 33 | bCH | ( θ 34 − θ 35 ) / 2 , ( θ 36 − θ 37 ) / 2 , ( θ 38 − θ 39 ) / 2 ( θ 40 − θ 41 ) / 2 , ( θ 42 − θ 43 ) / 2 , ( θ 44 − θ 45 ) / 2 | 0.9466 |
34 | bNH | ( θ 46 − θ 47 ) / 2 . | 0.9466 |
35 - 36 | bCC | ( θ 48 − θ 49 ) / 2 , ( θ 50 − θ 51 ) / 2 | 0.9265 |
37 - 38 | bCH2sc | α 52 + α 53 + α 54 + α 55 , α 56 + α 57 + α 58 + α 59 | 0.95715 |
39 - 40 | bCH2Roc | α 52 + α 53 − α 54 − α 55 , α 56 + α 57 − α 58 − α 59 | 0.95715 |
41 - 42 | bCH2Wag | α 52 − α 53 − α 54 + α 55 , α 56 − α 57 − α 58 + α 59 | 0.95715 |
Out of plane bending | |||
43 - 47 | ωC-H | ω60, ω61, ω62, ω63, ω64 | 0.9654 |
48 | ωN-H | ω65 | 0.9654 |
49 - 50 | ωC-C | ω66, ω67 | 0.98700 |
Torsion | |||
51 | τR1tri | ( τ 68 − τ 69 + τ 70 − τ 71 + τ 72 − τ 73 ) / 6 | 0.98867 |
52 | τR1asy | ( τ 68 − τ 70 + τ 71 − τ 73 ) / 2 | 0.98867 |
53 | τR1sym | ( − τ 68 − 2 τ 69 − τ 70 − τ 71 + 2 τ 72 − τ 73 ) / 12 | 0.98867 |
54 | R2torsion1 | τ 76 + b ( τ 74 + τ 78 ) + a ( τ 75 + τ 77 ) | 0.9966 |
55 | R2torsion2 | ( a − b ) ( τ 75 − τ 77 ) + ( 1 − a ) ( τ 74 − τ 78 ) | 0.9966 |
56 | τCH2 | τ 79 + τ 80 | 0.980 |
57 | τCCCC | τ 81 + τ 82 | 1.2000 |
a = cos144˚, and b = cos72˚.
and consist of medium intense bands [
1003 cm−1 in FT-Raman spectrum. This shows an excellent agreement with each other. The CH2 wagging vibrations are observed theoretically with less PED distribution.
The bands between 1400 and 1650 cm−1 in benzene derivatives are due to C-C stretching vibrations [
s.no | Experimental (cm−1) | Scaled frequencies (cm−1) | Intensity | Characterization of normal modes with PED (%)a,d | ||
---|---|---|---|---|---|---|
FT-IR | FT-Raman | IIRb | IRAc | |||
1. | 3404vw | 3398 | 0.033 | 1.12 | vNH(89) | |
2 | 3096 | 0.055 | 4.67 | vCH(99) | ||
3 | 3081 | 0.205 | 9.44 | vCH(99) | ||
4 | 3072 | 0.309 | 6.51 | vCH(99) | ||
5 | 3065w | 3063 | 0.158 | 7.04 | vCH(99) | |
6 | 3054 | 0.049 | 3.65 | vCH(99) | ||
7. | 2955 | 0.511 | 7.62 | vCH2as(78),vCH2ss(18) | ||
8 | 2946w | 2942 | 0.496 | 9.02 | vCH2as(65), vCH2ss(30) | |
9 | 2890 | 0.546 | 10.4 | vCH2ss(75), vCH2as(21) | ||
10 | 2874 | 0.59 | 7.46 | vCH2ss(59), vCH2as(26), bR2sym(10) | ||
11 | 2192 | 0.001 | 0.45 | gCC(61), tCCCC(38) | ||
12 | 1598w | 1611s | 1605 | 0.021 | 20.8 | vCC(69), bCH(17), bR1sym(10) |
13 | 1582 | 0.003 | 2.02 | vCC(50), vCN(15), bR2sym(14), bCH(10) | ||
14 | 1473 | 0.029 | 2.43 | bR2sym(25), vCC(22), bCH(20), vCN(16), gCC(10) | ||
15 | 1454w | 1447 | 0.339 | 16.4 | bCH2sc(29), bR2sym(25), gCC(16), vCN(14), tCCCC(10) | |
16 | 1446 | 0.353 | 17.6 | vCN(51), bR2sym(26), bCH2sc(15) | ||
17 | 1428 | 0.208 | 20.9 | vCN(39), bR2sym(20), bCH(15), vCC(12) | ||
18 | 1382 | 0.053 | 2.95 | bR2sym(35), vCC(16), vCN(12), gC(11) | ||
19 | 1346s | 1355 | 0.720 | 24.2 | vCN(49), bR2sym(37) | |
20 | 1308 | 0.069 | 7.83 | vCN(38), vCC(27), bR2sym(18) | ||
21 | 1272s | 1279 | 0.331 | 3.61 | bR2sym(31), vCC(22), vCN(14), bCH2wa(10) | |
22 | 1263 | 0.037 | 1.82 | bR2sym(31), vCC(22), vCN(14), bCH2wa(10) | ||
23 | 1230 | 0.033 | 2.12 | bNH(28)vCN(27), bR2sym(26) | ||
24 | 1194 | 0.121 | 3.74 | vCN(51), gCC(13), bCH2wa(10) | ||
25 | 1159w | 1168 | 0.107 | 2.53 | vCN(49), tCH2(22), bCH2wa(12) | |
26 | 1142 | 0.038 | 2.09 | bCH(66), vCC(14) | ||
27 | 1122w | 1122 | 0.016 | 2.13 | bCH(86), vCC(11) | |
28 | 1092 | 0.085 | 5.58 | bCH(28), bR2sym(21), bCH2wa(17), vCC(15) | ||
29 | 1065 | 0.012 | 3.27 | vCN(53), vCC(22) | ||
30 | 1052 | 0.013 | 4.38 | vCN(35), vCC(32), bCH(18) | ||
31 | 1017 | 0.065 | 4 | vCC(46), bCH(17), bR1tri(17), vCN(14) | ||
32 | 1003s | 1004 | 0.049 | 7.41 | bCH2Ro(48), tR2asy(19), tCCCC(13) | |
33 | 997 | 0.067 | 10.1 | bR1tri (49), vCC(42) | ||
34 | 983s | 986 | 0.035 | 4.24 | gCH(68), tR1tri(21) | |
35 | 955 | 0.005 | 2.71 | gCH(41), tCCCC(30) | ||
36 | 912s | 915 | 0.023 | 4.33 | gCH(65) | |
37 | 910 | 0.021 | 4.79 | vCC(60), vCN(27) |
38 | 840 | 0.027 | 0.37 | gCH(39), bR2sym(28), tCCCC(13), vCC(13) | ||
---|---|---|---|---|---|---|
39 | 839 | 0.0294 | 0.37 | bR2sym(52), vCC(20), vCN(19) | ||
40 | 805 | 0.0837 | 0.37 | vCN(44), bR2sym(22), tR1tri(17) | ||
41 | 790 | 0.289 | 5.4 | vCN(67), bR2sym(10) | ||
42 | 769 | 0.0234 | 1.4 | vCN(44), gCC(24), bR2sym(16), tCCCC(13) | ||
43 | 720 | 0.172 | 3.6 | gCH(55), vCN(23) | ||
44 | 694 | 0.135 | 5.29 | bR2sym(49), vCN(33) | ||
45 | 668w | 660 | 0.0228 | 3.8 | bR2sym(61), vCN(18) | |
46 | 615w | 621 | 0.0575 | 4.2 | bR1asy(69) | |
47 | 592 | 0.0459 | 1.65 | bR2sym(42), vCN(35), gCC(13) | ||
48 | 522 | 0.00727 | 4 | bR2sym(44), vCN(39) | ||
49 | 477 | 0.00617 | 0.52 | bR2sym(55), vCN(41) | ||
50 | 450 | 0.00435 | 10.8 | tCCCC(94) | ||
51 | 343w | 347 | 0.0162 | 32 | bR2sym(68), vCN(31) | |
52 | 310 | 0.0102 | 0.61 | bR2sym(42), vCN(41) | ||
53 | 276 | 0.367 | 35 | bR2sym(34), tCCCC(28), tR2asy(18), tR2sym(12) | ||
54 | 169 | 0.0199 | 11 | tCCCC(67), tCH2(14), tR2asy(11) | ||
55 | 142 | 0.0416 | 17 | bR2sym(58), vCN(19), tCCCC(12) | ||
56 | 115 | 0.0344 | 18 | tCCCC(40), bR2sym(36) | ||
57 | 77s | 77 | 0.00256 | 4 | tCCCC(100) |
aAbbreviations: v, stretching; b, in plane bending; g, out of plane bending; t, torsion; ss, symmetrical stretching; as, asymmetrical stretching; tri, trigonal deformation; sym, symmetrical deformation; asy, asymmetric deformation, vs, very strong; s, strong; m, medium; w, weak; vw, very weak; bRelative absorption intensities normalized with highest peak absorption equal to 1. cRelative Raman intensities calculated by Equation (1) and normalized to 100. dOnly PED contributions ≥10% are listed.
theoretically observed at frequency 1605 cm−1. The remaining C-C stretching vibrations are observed theoretically at 1582 cm−1 and 1012 cm−1 and some of the frequencies are having less PED distribution. The C-C out of plane vibration predicted theoretically at 2192 cm−1 and no Experimental bands were observed.
Hetero cyclic compound having an N-H group shows its stretching absorption in the region 3500 - 3200 cm−1 [
The ring stretching vibrations have great significance during the Infrared spectrum of benzene derivatives since ring stretching vibrations include high characteristic modes of the aromatic rings. As a result of the substitution to the aromatic ring of benzene derivatives several ring vibrations be affected. The skeletal vibrations are due to the coupled vibrations in the six ring carbon atoms. The semi circle stretching vibrations such as ring C=C and C-C vibrations take place in the region 1400 - 1625 cm−1. Due to the electro negativity of nitrogen atom there are small changes in frequencies are observed for these modes. Apart from ring C-C stretching modes, trigonal deformation for related benzene ring, symmetric and asymmetric deformation modes for both the rings are assigned as listed in
NBO analysis for the title compound was carried out at the 6-311++G** basis set to calculate delocalization of the electron density within the molecule. NBO calculations are used to understand the interactions between filled and virtual orbitals of one subsystem with another subsystem. These interactions possibly will enhance the analysis of intra- and inter molecular interactions. The hyperconjugative interaction energy is deduced from the second-order perturbation approach [
These interactions are observed as raise in electron density (ED) in C-C, C-N antibonding orbital to weaken the particular bonds. As listed in
Non linear optical (NLO) materials play a vital role in optical switching devices and industrial applications. The first hyperpolarizability β, dipole moment µ as well as polarizability α are computed using HF/6–31G (d, p) basis set on the basis of the finite-field approach. The complete equations for calculating the magnitude of total static dipole moment μ, the mean polarizability α0, the anisotropy of the polarizability Δα and the mean first hyperpolarizability β0, using the x, y, z components from Gaussian 03W output are as follows
μ = μ x 2 + μ y 2 + μ z 2 (2)
α o = α x x + α y y + α z z 3 (3)
Donor(i) | Type | Ed/e | Acceptor(j) | Type | Ed/e | E(2)a (kJ・mol−1) | E(i)-E(j)b(a.u) | f(I,j)c(a.u) |
---|---|---|---|---|---|---|---|---|
C1-C2 | σ | 1.98898 | N11-H12 | σ* | 0.01847 | 2.68 | 1.05 | 0.047 |
C1-N11 | σ | 1.98586 | C3-C4 | σ* | 0.03966 | 4.34 | 1.18 | 0.064 |
C1-H13 | σ | 1.98923 | C2-H21 | σ* | 0.02002 | 1.60 | 0.97 | 0.035 |
C1-H20 | σ | 1.98675 | C3-N11 | σ* | 0.04973 | 1.59 | 0.95 | 0.035 |
C2-N10 | σ | 1.98133 | C3-C4 | σ* | 0.03966 | 8.65 | 1.14 | 0.089 |
C2-H14 | σ | 1.98369 | C3-N10 | σ* | 0.23563 | 1.74 | 0.55 | 0.029 |
C2-H21 | σ | 1.97896 | C3-N10 | σ* | 0.23563 | 2.00 | 0.55 | 0.031 |
C3-C4 | σ | 1.97168 | C2-N10 | σ* | 0.01298 | 2.98 | 1.03 | 0.050 |
σ | 1.97168 | C3-N10 | σ* | 0.01771 | 2.23 | 1.28 | 0.048 | |
σ | 1.97168 | C4-C5 | σ* | 0.02151 | 2.21 | 1.23 | 0.047 | |
σ | 1.97168 | C4-C7 | σ* | 0.02205 | 2.27 | 1.23 | 0.047 | |
C3-N10 | σ | 1.98849 | C3-C4 | σ* | 0.03966 | 2.77 | 1.33 | 0.055 |
C3-N10 | σ | 1.93659 | C2-H14 | σ* | 0.01479 | 2.86 | 0.78 | 0.043 |
σ | 1.93659 | C2-H21 | σ* | 0.02002 | 3.53 | 0.77 | 0.047 | |
σ | 1.93659 | C4-C7 | σ* | 0.37095 | 7.54 | 0.34 | 0.049 | |
C4-C5 | σ | 1.97274 | C3-C4 | σ* | 0.03966 | 2.46 | 1.16 | 0.048 |
σ | 1.97274 | C3-N11 | σ* | 0.04973 | 2.55 | 1.12 | 0.048 | |
σ | 1.97274 | C4-C7 | σ* | 0.02205 | 3.83 | 1.25 | 0.062 | |
σ | 1.97274 | C5-C6 | σ* | 0.01431 | 2.35 | 1.27 | 0.047 | |
C4-C7 | σ | 1.97515 | C3-C4 | σ* | 0.03966 | 2.28 | 1.17 | 0.046 |
σ | 1.97515 | C3-N10 | σ* | 0.01771 | 2.05 | 1.31 | 0.046 | |
σ | 1.97515 | C4-C5 | σ* | 0.02151 | 3.79 | 1.26 | 0.062 | |
σ | 1.97515 | C7-C9 | σ* | 0.01479 | 2.59 | 1.27 | 0.051 | |
σ | 1.97515 | C9-H19 | σ* | 0.01209 | 2.16 | 1.17 | 0.045 | |
C4-C7 | σ | 1.65029 | C3-N10 | σ* | 0.23563 | 16.97 | 0.30 | 0.065 |
Σ | 1.65029 | C5-C6 | σ* | 0.29661 | 19.17 | 0.29 | 0.067 | |
σ | 1.65029 | C8-C9 | σ* | 0.32715 | 19.81 | 0.28 | 0.067 | |
C5-C6 | σ | 1.98034 | C3-C4 | σ* | 0.03966 | 3.50 | 1.52 | 0.065 |
σ | 1.98034 | C4-C5 | σ* | 0.02151 | 2.82 | 1.27 | 0.053 | |
Σ | 1.98034 | C6-C8 | σ* | 0.01603 | 2.52 | 1.27 | 0.050 | |
σ | 1.98034 | C8-H17 | σ* | 0.01217 | 2.29 | 1.17 | 0.046 | |
C5-C6 | σ | 1.65967 | C4-C7 | σ* | 0.37095 | 19.94 | 0.28 | 0.067 |
σ | 1.65967 | C8-C9 | σ* | 0.32715 | 21.05 | 0.28 | 0.069 | |
C5-H15 | σ | 1.98061 | C4-C7 | σ* | 0.02205 | 4.31 | 1.08 | 0.061 |
σ | 1.98061 | C6-C8 | σ* | 0.01603 | 3.65 | 1.09 | 0.056 | |
C6-C8 | σ | 1.98120 | C5-C6 | σ* | 0.01431 | 2.54 | 1.28 | 0.051 |
σ | 1.98120 | C5-H15 | σ* | 0.01359 | 2.31 | 1.19 | 0.047 | |
σ | 1.98120 | C8-C9 | σ* | 0.01572 | 2.43 | 1.27 | 0.050 | |
C6-H16 | σ | 1.98266 | C4-C5 | σ* | 0.02151 | 3.80 | 1.09 | 0.058 |
σ | 1.98266 | C8-C9 | σ* | 0.11572 | 3.54 | 1.10 | 0.056 | |
---|---|---|---|---|---|---|---|---|
C7-C9 | σ | 1.97999 | C3-C4 | σ* | 0.03966 | 3.45 | 1.17 | 0.057 |
σ | 1.97999 | C4-C7 | σ* | 0.02205 | 3.09 | 1.27 | 0.056 | |
C7-H18 | σ | 1.98179 | C4-C5 | σ* | 0.02151 | 4.07 | 1.10 | 0.060 |
σ | 1.98179 | C8-C9 | σ* | 0.01572 | 3.51 | 1.10 | 0.056 | |
C8-C9 | σ | 1.98101 | C6-C8 | σ* | 0.01603 | 2.42 | 1.27 | 0.049 |
σ | 1.98101 | C7-C9 | σ* | 0.01476 | 2.59 | 1.27 | 0.051 | |
σ | 1.98101 | C7-H18 | σ* | 0.01312 | 2.35 | 1.17 | 0.047 | |
C8-C9 | σ | 1.66151 | C4-C7 | σ* | 0.37095 | 20.44 | 0.28 | 0.068 |
σ | 1.66151 | C5-C6 | σ* | 0.29661 | 18.58 | 0.29 | 0.066 | |
C8-H17 | σ | 1.98315 | C5-C6 | σ* | 0.01431 | 3.50 | 1.11 | 0.056 |
σ | 1.98315 | C7-C9 | σ* | 0.01476 | 3.60 | 1.10 | 0.056 | |
C9-H19 | σ | 1.98276 | C4-C7 | σ* | 0.02205 | 3.78 | 1.09 | 0.057 |
σ | 1.98276 | C6-C8 | σ* | 0.01603 | 3.53 | 1.10 | 0.056 | |
N11-H12 | σ | 1.98046 | C3-N10 | σ* | 0.01771 | 2.62 | 1.25 | 0.051 |
σ | 1.98046 | C3-N10 | σ* | 0.01771 | 2.14 | 0.69 | 0.036 | |
LP | ||||||||
N10(1) | σ | 1.91978 | C1-C2 | σ* | 0.02495 | 4.86 | 0.70 | 0.053 |
σ | 1.91978 | C3-N11 | σ* | 0.04973 | 11.92 | 0.78 | 0.087 | |
N11(1) | σ | 1.81255 | C1-H13 | σ* | 0.02044 | 4.37 | 0.74 | 0.053 |
σ | 1.81255 | C1-H20 | σ* | 0.01525 | 3.21 | 0.75 | 0.046 | |
σ | 1.81255 | C3-N10 | σ* | 0.23563 | 29.04 | 0.34 | 0.090 | |
C4-C7 | σ* | 0.37095 | C3-N10 | σ* | 0.23563 | 118.65 | 0.02 | 0.070 |
C5-C6 | σ* | 0.29661 | C5(4) | π* | 0.00043 | 2.09 | 0.87 | 0.099 |
σ* | 0.29661 | C6(4) | π* | 0.00037 | 2.13 | 0.72 | 0.091 |
aE(2) means energy of hyper conjugative interaction (stabilization energy). bEnergy difference between donor and acceptor i and j NBO orbitals. cF(i, j) is the Fock matrix element between i and j NBO orbitals.
Δ α = 2 − 1 / 2 [ ( α x x − α y y ) 2 + ( α y y − α x x ) 2 + 6 α x x 2 ] 1 / 2 (4)
β = ( β x 2 + β y 2 + β z 2 ) 1 / 2 (5)
and
β x = β x x x + β x y y + β x z z (6)
β y = β y y y + β x x y + β y z z (7)
β z = β z z z + β x x z + β y y z (8)
The calculated first hyperpolarizability of the 2PI using HF/6-31G(d, p) is 1.0043389 × 10−30 esu and the dipole moment is 5.70065 Debye shown in
Property | 2-phenyl-2-imidazoline |
---|---|
Total energy (eV) | −12401.75816 |
EHOMO (eV) | −5.82160670 |
ELUMO (eV) | −0.78749789 |
EHOMO-ELUMO (eV) | 5.03410881 |
Electronagativity (χ) eV | 3.304552295 |
Chemical hardness (η) eV | −2.517054405 |
Electrofilicity index (ω) eV | −2.1692153035 |
Global Softness (σ)eV | −0.3972897836 |
Total energy change (ΔET) eV | 0.62926360125 |
Dipole moment (D) | 5.70065 |
µ and α components | HF/6-31G(d,p) | β components | HF/6-31G(d,p) |
---|---|---|---|
µx | 0.104085 | βxxx | −91.4409918 |
µy | 0.2171718 | βxxy | −14.7087352 |
µz | −1.065635 | βxyy | −44.654681 |
µ(D) | 1.19357523 | βyyy | 0.6127935 |
αxx | 143.1369019 | βxxz | −65.4861453 |
αxy | 4.2163498 | βxyz | 17.3286849 |
αyy | 56.0399983 | βyyz | −2.0474112 |
αxz | −6.356907 | βxzz | 56.4680477 |
αyz | 17.5520362 | βyzz | 11.6736082 |
αzz | 96.5295611 | βzzz | −17.1315722 |
α(esu) | 14.607899 × 10−12 esu | β total (esu) | 1.0043389 × 10−30 esu |
linear optical material.
Both the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are the main orbitals take part in chemical stability [
The UV-Visible absorption spectrum of the title molecule using SAC CI/6-311++G** basis set is performed to determine the lower lying excited states. The computed results involving the vertical excitation energies, oscillator strength (f) and wavelength are carried out and compared with measured investigational wavelength. These are presented in
Molecular electrostatic potential (MEP) mapping is very useful in the investigation of the molecular structure with its physiochemical property relationships
[
V ( r ) = ∑ A N [ ( Z A / | r − R A | − ∫ ρ ( r ′ ) d 3 r ′ / | r − r ′ | ) ] (9)
On the basis of vibrational analyses and statistical thermodynamics, the standard thermodynamic functions: heat capacity, internal energy, entropy and enthalpy were calculated using Moltranv. 2.5 [
No. | Exp. Wavelength | Energy (cm−1) | Wavelength (nm) | Osc. Strength | Symmetry | Major contrib. |
---|---|---|---|---|---|---|
1 | 273.00 | 36,683.15536 | 272.60 | 0.0658 | Singlet-A | HOMO- > LUMO (92%) H-1- > LUMO (5%) |
2 | -- | 41,541.06624 | 240.72 | 0.0214 | Singlet-A | H-3- > LUMO (86%) H-1- > LUMO (7%), HOMO- > LUMO (−3%) |
3 | -- | 49,875.25072 | 200.50 | 0.0059 | Singlet-A | H-3- > L + 1 (90%) H-2- > L + 1 (−3%), H-1- > L + 1 (6%) |
4 | -- | 58,519.15424 | 170.88 | 0.0015 | Singlet-A | H-5- > LUMO (97%) |
5 | -- | 62,270.4648 | 160.58 | 0.0074 | Singlet-A | HOMO- > L + 4 (83%)H-4- > LUMO (−3%), H-3- > L + 2 (−2%), H-1- > L + 3 (−3%), HOMO- > L + 5 (−2%) |
6 | -- | 65,521.70816 | 152.62 | 0.0089 | Singlet-A | HOMO- > L + 5 (72%)H-4- > LUMO (3%), H-2- > L + 3 (−3%), H-1- > L + 2 (8%), HOMO- > L + 4 (2%) |
7 | -- | 67,402.60608 | 148.36 | 0.0352 | Singlet-A | H-3- > L + 3 (81%) H-1- > L + 4 (−5%) |
8 | -- | 68,145.44784 | 146.74 | 0.0067 | Singlet-A | H-7- > LUMO (82%)H-9- > LUMO (6%), HOMO- > L + 6 (−2%) |
9 | -- | 69,112.51328 | 144.69 | 0.0245 | Singlet-A | H-1- > L + 4 (60%), HOMO- > L + 6 (13%)H-8- > LUMO (2%), H-3- > L + 3 (3%), H-1- > L + 3 (−7%) |
Temperature (K) | CV (J/K/mol) | CP (J/K/mol) | U (J/K/mol) | H (J/K/mol) | S (J/K/mol) | G (J/K/mol) |
---|---|---|---|---|---|---|
50 | 41.711 | 50.025 | 463.417 | 463.833 | 257.095 | 450.978 |
100 | 58.629 | 66.944 | 465.937 | 466.768 | 297.116 | 437.057 |
150 | 74.786 | 83.100 | 469.266 | 470.513 | 327.267 | 421.423 |
200 | 94.048 | 102.363 | 473.468 | 475.131 | 353.712 | 404.388 |
250 | 117.122 | 125.436 | 478.732 | 480.811 | 378.975 | 386.067 |
300 | 142.556 | 150.871 | 485.223 | 487.717 | 404.079 | 366.493 |
350 | 168.474 | 176.789 | 492.989 | 495.899 | 429.273 | 345.654 |
400 | 193.457 | 201.772 | 502.040 | 505.366 | 454.524 | 323.557 |
450 | 216.713 | 225.028 | 512.313 | 516.055 | 479.662 | 300.207 |
500 | 237.953 | 246.268 | 523.690 | 527.848 | 504.490 | 275.603 |
that the values of CP, CV, U, H and S increase with increase of temperature from 100 to 500 K. The thermo dynamical parameters were fitted with the temperature by quadratic, linear and quadratic formulas respectively.
Further thermo dynamical data provides the needful information about the molecule. Thermo dynamical data used to estimate directions of chemical reactions according second law of thermodynamics in the thermo chemical field.
The theoretical and experimental FT-IR, FT-Raman spectral studies and NBO analysis of 2PI were carried out and reported. Complete vibrational analysis of 2PI was performed on the basis of DFT calculations at the B3LYP/6-311++G** level of theory and presented. The 42 normal modes of vibrations were ambiguously assigned based on the result of PED output obtained from normal coordinate analysis. There was a qualitative agreement among the calculated and observed frequencies. The NBO analysis shows strong intermolecular hyperconjugative interactions of electron. The strong delocalization of electrons in the molecule is primary to a stabilization of the molecule.
The First author, Y. Sushma Priya is thankful to Sophisticated Analytical Instrumentation Facility (SAIF), IIT Madras, Chennai and Analytical Chemistry laboratories for their services. The corresponding author, A. Veeraiah is highly grateful to Science and Engineering Research Board, Department of Science and Technology, Government of India for the financial assistance provided. Further, the authors are highly grateful to Prof. T. Sundius for Molvib program.
Priya, Y.S., Rao, K.R., Chalapathi, P.V. and Veeraiah, A. (2018) Vibrational and Electronic Spectra of 2-Phenyl-2-Imidazoline: A Combined Experimental and Theoretical Study. Journal of Modern Physics, 9, 753-774. https://doi.org/10.4236/jmp.2018.94049
No.(i) | Symbol | Type | Definitiona |
---|---|---|---|
Stretching | |||
1 - 8 | Ri | CC | C1-C2, C3-C4, C4-C5, C5-C6, C6-C8, C8-C9, C4-C7, C7-C9 |
9 - 12 | ri | CN | C1-N11, C2-N10, C3-N11, C3-N10 |
13 - 21 | Pi | CH | C5-H15, C6-H16, C8-H17, C9-H19, C7-H18, C1-H20, C1-H13, C2-H14, C2-H21. |
22 | Qi | NH | N11-H12. |
In-Plane bending | |||
23 - 28 | bi | Ring1 | C4-C5-C6, C5-C6-C8, C6-C8-C9, C8-C9-C7, C9-C7-C4, C7-C4-C5. |
29 - 33 | bi | Ring2 | C1-C2-N10, C2-N10-C3, N10-C3-N11, C3-N11-C1, N11-C1-C2. |
34 - 43 | bi | CCH | C4-C7-H18, C9-C7-H18, C7-C9-H19, C8-C9-H19, C9-C8-H17, C6-C8-H17, C8-C6-H16, C5-C6-H16, C4-C5-H15, C6-C5-H115, C1-C2-H14, N10-C2-H14. |
44 - 47 | θi | CN | C1-N11-H12, C3-N11-H12, N11-C3-C4, N10-C3-C4. |
48 - 49 | θi | CC | C7-C4-C3, C5-C4-C3. |
50 - 53 | θi | NCH | N11-C1-H13, N11-C1-H20, N10-C2-H14, N10-C2-H21. |
54 - 55 | θi | HCH | H13-C1-H20, H14-C2-H21. |
Out-of-plane bending | |||
56 - 60 | ὠi | CH | H15-C5-C4-C6, H16-C6-C5-C8, H17-C8-C6-C9, H19-C9-C8-C7, H18-C7-C9-C4. |
61 | φi | NH | H12-N11-C3-C1 |
62 | πi | CN | C4-C3-N10-N11 |
63 | πi | CC | C3-C4-C7-C5 |
Torsion | |||
64 - 69 | τi | τRING1 | C4-C5-C6-C8, C5-C6-C8-C9, C6-C8-C9-C7, C8-C9-C7-C4, C9-C7-C4-C5, C7-C4-C5-C6 |
70 - 74 | τi | τRING2 | C1-C2 -N10-C3, C2-N10-C3-N11, N10-C3-N11-C1, C3-N11-C1-C2, N11-C1-C2-N10 |
75 - 82 | τi | τCH2 | C3-N11-C1-H13, C3-N11-C1-H20, N10-C2-C1-H13, N10-C2-C1-H20, N11-C1-C2-H14, N11-C1-C2-H21, C3-N10-C2-H14, C3-N10-C2-H21. |
83 - 84 | τi | Butterfly | N10-C3-C4-C7, C5-C4-C3-N11. |
aFor numbering of atom refer