J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 Journal of the Nigerian Society of Physical Sciences Computational studies on Emodin (C15H10O5) from Methanol extract of Pteridium acquilinum leaves M. E. Khana, E. E. Etimb,, V. J. Anyamc, A. Abeld, I. G. Osigbemhee, C. T Agberf aDepartment of Chemistry, Federal University Lokoja, Kogi State, Nigeria bDepartment of Chemical Science, Federal University Wukari Taraba State Nigeria cDepartment of Chemistry University of Agriculture Makurdi, Benue State Nigeria dDepartment of Pure and Applied Chemistry, Adamawa State University, Mubi, Adamawa State Nigeria eDepartment of Industrial Chemistry, Federal University Lokoja, Kogi State, Nigeria fDepartment of Chemistry, Benue State University, Makurdi, Benue State, Nigeria Abstract This research isolated, characterized, and studied the computational and frequency calculations of emodin, extracted from the leaf extract of Pteridium acquilinum using methanol. Vacuum liquid and tin layer Chromatographic techniques were used for the purification of the molecule. The (VLC purified), fraction was analyzed by Nuclear magnetic resonance (NMR) and the chemical structure of the compound isolated (an- thraquinone), was confirmed by 1H & 13C-NMR analyses as emodin (C15H10O5) Computational and frequency studies were done on the isolated molecule. Optimized geometry, IR frequencies, Bond distances (R) and angles (A), Dipole moments and other parameters have been computationally determined for the isolated molecule from quantum chemical calculations using the GAUSSIAN 09 retinue programs. Experimentally determined and computationally measured IR frequencies agreed perfectly with each other. Computational studies have been used to predict unobserved chemical phenomena like design of new drugs and materials such as the positions of constituent atoms in relationship to their relative and absolute energies, electronic charge densities, dipoles, higher multiple moments, vibrational frequencies, relativity or other spectroscopic quantities and cross sections for collision with other molecules. This is the first time this anthraquinone, [emodin], with most of the parameters examined is reported from P. aquilinum. DOI:10.46481/jnsps.2021.301 Keywords: Pteridium aquiilinum, Isolated & characterized, Chromatography, Emodin, Optimized geometry, Computational and frequency studies. Article History : Received: 14 July 2021 Received in revised form: 14 October 2021 Accepted for publication: 01 November 2021 Published: 29 November 2021 c©2021 Journal of the Nigerian Society of Physical Sciences. All rights reserved. Communicated by: B. J. Falaye 360 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 361 1. Introduction The phenomenon of screening plants for the presence of phyto-molecules of medicinal importance is common place. Nat- ural products have pharmaceutical / pharmacological activity that are useful in treating diseases and are the starting points for drugs discovery from which synthetic drug analogues can be prepared with improved efficacy, potency, safety and purity [1], when isolated, synthetic strategies and tactics are used by organic Chemists providing challenging mechanisms that per- mit the biologically active product to the target site. A review reported that 577 plant species have been used traditionally due to the secondary metabolites in them, [2 & 3]. Africa is blessed with its natural pharmacy of variety of plants. Chemists take the pain to analyse these plants‘ secondary metabolites for the benefit of mankind as they are precursors for modern drugs, [4]. Based on this concept and theory, the optimal geometry of the eagle fern was calculated. Pteridium aquilinum, brake or com- mon bracken, also known as ”eagle fern,” is a species of fern occurring in temperate and subtropical regions in both hemi- spheres. The extreme lightness of its spores has led to its global distribution, [5]. The large, roughly triangular fronts of the fern are herb-like rhizomes produced singly, arising upwards from an underground, and grow to 1–3 m (3–10 ft) tall; the main stem, or stipe is up to 1 cm (0.4 in) diameter at the base. It is an adaptable plant, which readily colonies disturbed areas. It is a vascular plant that reproduces via spores and has nei- ther seeds nor flowers. It differs from moss by being vascular and it‘s of the class Polypodiopsidae. They are the best house purifying plants with their evergreen leaves that help rid the home of harmful toxins and improve humanity by helping to restore moisture to air naturally and also combat winter dry- ness by raising indoor humidity. They are used as cooked veg- etable in Baffousam (Cameroon) and consume with Vernonia amygdalina, Delile and triumfetta rhomboidae. When soaked in wood ash for 24 – 36 hours, free tannic acids are removed and the crosiers consumed and sold as “warabi” or “zenmai in Japan. Rhizomes are consumed in France, Madagascar, and the Canary Island and also used as starch and confections. Leaves are used as straw and bedding for cattle, also to filter oil and palm wine. In Cote d‘Ivoire, powdered crosiers are applied to old wounds and also as enema to overcome sterility in women. The rhizomes are mixed with Zingiber officinal in juice form and taken as aphrodisiac and with others to calm mental dis- ability. In China, water soaked leaves are used as pesticides. The ash used in Europe for glass and soap production, [6]. Studies carried on Pteridium acquilinumin included, potential and historical uses for braken (L) Kuhn, in organic agriculture where the braken were considered a serious weed species, due to toxic constituents and negativity on agriculture and conser- vation, [7]. The resistance of P. acquilinum (L)Kuhn, to insect attack by Trichoplusia ni (Hubn) where dried braken leaf meals and extracts of the leaf was incorporated into an artificial diet for trichoplusia ni larvae and studied, [8]. Isolation and char- acterization of the bio assay active molecule(s) from the ex- Email address: emmaetim@gmail.com (E. E. Etim ) tract of the leaves of Pteridium acquilinum using the aqueous and methanolic leaf extracts was carefully examined and the extracts used in boosting some female rats hormones, [2]. The plant has many chemical compounds such as emodin, quercetin, shikimic acid, prunasin, ptaquiloside and a ‘bleeding factor’ of other known and unknown structures [9] Almost every health challenge in the world has a solution in nat- ural products. Thus, the discovery of pharmaceutical drugs re- mains one of the preeminent tasks in biomedical and related re- search areas. Advances in science and technology coupled with the development of quantum chemistry, new computational mod- els and software including user-friendly interfaces have reduced the barriers to the application of computational tools in the dis- covery and structure elucidation of natural products. Conse- quently, the use of computational chemistry software as a tool to discover and determine the structure of natural products has become more common in recent years. There are several reports of recent studies where computational chemistry is applied to facilitate the discovery and structure elucidation of various nat- ural products with the view to giving insights about the isolated compounds, [10, 11, 12, 13 & 14]. Computational studies are based on quantum mechanics and ba- sic physical constants, with involvement of approximations, but tractable; thus, help find entirely new chemical objects. They are used to find a starting point for a laboratory synthesis or to assist in understanding experimental data such as position and source of spectroscopic peaks and to predict the possibility of entirely unknown molecules or to explore reaction mecha- nisms not readily studied via experiments. This work is thus, designed to carry out the characterization and identification of bioactive compounds from P. aquilinum leaf extracts and the quantum chemical calculations are employed to further scruti- nised and give a better insight about the isolated molecule for the enhancement of human life. 2. Materials and Methods 2.1. Sample Collection and Authentication Leaves of P. acquilinum that were still green but matured, were collected in and around Michika L. G. A, Adamawa State on 28th July 2014. Authentication of the plant species was by [15], in the State Ministry of Forestry, Mubi North LGA, Adamawa State and a specimen of the plant was kept in their Herbarium. The Forestry Herbarium Index number (FHI) is 1030. 2.2. Preparation of the plant Sample Leaves of the plant were properly washed with running tap water to avoid dust and other unwanted materials that most have accumulated on the leaves from their natural habitat. Then, dust free leaves were kept to dry under shade in the Chemistry labo- ratory of Adamawa State University Mubi. These dried leaves were pulverized by using mortar and pestle. Finally, fine pow- der was obtained from the pulverized leaves by sieving through the kitchen strainer and used for extraction. 361 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 362 2.3. Successive Extractions using Microwave Assisted Extrac- tion (MAE) 250g of the powdered sample was poured into a glass (2.5 L) and 500cm3 of normal-hexane was added to it. The bottle was then put into the microwave set at defrost every 3 minutes and removed and cooled. This was Repeated 10 times. Af- ter filtration, the residues were further extracted similarly using ethyl acetate followed by methanol, [16], and the yields thus: N-hexane, 10g, ethyl acetate, 15g and methanol, 28g respec- tively. 2.4. Vacuum Liquid Chromatography (VLC) 15g of the methanol extract was dissolved and mixed with celite and left to dry. The dried mixture was then loaded on the VLC that had already been packed with silica gel. It was then rinsed 20 times with 20 cm3 each of n-hexane and ethyl acetate. Ethyl acetate - methanol gradient was used to elute the column and 60 fractions collected. 2.5. Thin Layer Chromatography TLC was carried out on all the fractions using a solvent gra- dient system of 9:1 v/v chloroform in methanol. Fractions 12- 19 were combined and allowed to dry. The dried sample was then dissolved in methanol but yellow crystals were left un- dissolved. This was carefully washed. A yellow component was thus purified, spotted on the TLC plate and was labelled (F1), [17] 2.6. Sephadex column Dissolved components of fractions 12-19, were put on a column loaded with sephadex and eluted with solvent gradient system of 1:3:3 v/v/v methanol, chloroform and ethyl acetate. Seven (7) fractions of 2 cm3 each were collected and spotted on the TLC plate labelled (a) and (b) 2.7. Analysis with Nuclear Magnetic Resonance (NMR) Ma- chine Fraction (a), RF: 0.65, of the VLC, (with a yellow colour) that was purified with the Sephadex column was sent for NMR analyses. The NMR spectra were run at SIPBS, University, Strathclyde, Glasgow, United Kingdom on JEOL-LA-400 MHz FT-NMR spectrophotometer [2]. 2.8. Quantum Chemical Calculations Current advances in theoretical and computational thermo- dynamics have made it easier to study systems, molecular in- teractions, reactions and predict parameters which would have been experimentally impossible or very difficult to study. The GAUSSIAN 09 retinue of programs was used for all the quan- tum chemical calculations reported here. The molecule was op- timized at the M06-2X level of theory with the 6 - 31g (d,p) 6 - 31+G* basis set. The M06-2X functional is a high-non- local functionality with double amount of nonlocal exchange (2X). The optimized structure was stable with real frequencies as shown from the frequency calculations [18, 19, 20, 22-26]. 3. Results and Discussion Detailed computational and frequency studies of the molecule was done and all thermodynamic parameters investigated. This could help to properly identify and justly place the molecule in its chemical context and use it adequately in bioactivity stud- ies and for some bioassays in researches. These investigations and detail analyses were carried out with the aid of Chromatog- raphy (VLC, TLC and Sephadex) and other available spectro- scopic techniques like Nuclear magnetic resonance (NMR) (1H & 13C-NMR). The computational and frequency studies were carried out using GAUSSIAN 09 retinue programs thus; Lev- els of theory set: HF/6-311G, Charge = 0, Multiplicity = 1, Stoichiometry C15H10O5, Framework group C1[X(C15H10O5)], Deg. of freedom: 84, Full point group : C1, Largest Abelian subgroup :C1. Largest concise Abelian subgroup: C1, Van-Der- Waal spheres, IR & Raman spectra, Bond distances (R) and angles (A), Dipole moments; field –independent basis (Debye), Rotational constants, HOMO-LUMO structures, Molecular Or- bital levels and the Band gaps of: 0.33925 were investigated to bring the structural definition of the molecule, as ‘emodin’ Qualitative TLC, results of P. aquilinum leaf extract (Table 1), performed on the methanol crude extracts are presented and discussed. The two spots detected on the TLC plate of the sephadex column fraction; yellow colour, implied that there are two different components in the extract. Retention factor (Rf) = distance travelled by the solution/ distance travelled by the solvent front; Rf (Fa) = 2.2/3.7 = 0.59 and Rf (Fb) = 2.5/3.7 = 0.68. Table 1. Result of Qualitative TLC of Leaf methanol extract of P. aquilinum Extract No. of spots R f Quantity leaf 1 2.2/3.7 = 0.59 0.5mg leaf 1 2.5/3.7=0.68 (small) 3.1. Optimized Geometry Figure 1, portrays the optimized geometry of P. aquilinum isolated from the methanol extract. Optimized geometry of P. aquilinum, (Figure 1), obtained at the M062x/6-31g (d,p) level of theory and the Van-Der-Waals sphere (Figure 2), are representations of emodin illustrating where a surface might reside for the molecule based on the hard cutoffs of Van-Der-Waals radii for the individual atoms making up the molecule. [12] 3.2. FTIR Spectra Data for Isolated Emodin The FTIR spectrum displayed C-OH stretching hydroxyl groups at 3500cm−1, C-H asymmetric stretching in -CH3 at 2925 cm−1, -CH2- stretching frequency at 2900 cm−1, -C=O asymmetric stretching in Carbonyl at 1750, and C-H bending in CH3 at 1400 cm−1. FTIR analysis of isolated emodin is pre- sented in Table 2 and it also attested to the IR spectrum of the computationally obtained levels at the M062x/6-31g (d, p) of the molecule.. 362 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 363 Table 2. The FTIR Spectral Data and Interpretation of Isolated methanol extract Frequency range cm -1 Vibrational mode Remarks 3500 C –OH stretching Hydroxyl 2925 C-H-Asymmetric stretching -CH3 2900 C-H Stretching frequen- cies -CH2- 1750 C=O Stretching Carbonyl 1400 C-H Bending -CH2- Figure 1. Models of optimized geometry of P. aquilinum obtained at the M06 2x /6-31g (d,p) level of theory All the major peaks obtained experimentally are in con- sonance with those obtained computationally at the M062x/6- 31g (d, p) level. This further validates both the experimen- tal and computational results. The frequency from 8cm−1 to 3902cm−1 and the corresponding intensity for the IR spectrum obtained at the M062x/6-31g (d, p) level are supporting infor- mation. Regarding microwave (or rotational) spectroscopy, this molecule is active with a total dipole moment of 3.7801 Debye obtained at the M062x/6-31g (d, p) level, Table 7. Also, its mi- crowave spectrum has been measured. As an asymmetric top molecule with three different moments of inertia correspond- ing to the three principal axes, this molecule is expected and it has three different rotational constants. At the M062x/6-31g (d,p) level, the rotational constants obtained for the molecule Figure 2. Van-Der-Waals sphere for P. aquilinum obtained at the M062x/6-31g (d, p) level of optimized geometry Figure 3. IR Spectrum are 0.7462698, 0.2467690 and 0.1856618 GHz corresponding to the A, B and C rotational constants respectively, Table 8. Figure 3 portrays the IR spectrum of emodin obtained at the M062x/6-31g (d, p) level of theory, 1HNMR and 13CNMR Spectra interpretation for methanol extract. 1H NMR of the sample (Table 3) contains; 4 sets of aro- matic peaks (7.53, 7.23, 7.12 and 6.62), two sets of phenolic peaks (12.12 and 12.06 ) and one set of methyl groups (2.38, attached to aromatic ring) protons. 13C NMR chemical shift values (Table 4) revealed the pres- ence of; 12 aromatic peaks (166.2, 164.9, 161.8, 148.7, 135.7, 133.4, 124.6, 121.0, 113.9, 109.5, 108.5 and 108.4), 2 carbonyls 363 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 364 Figure 4. Bonf distances and Angles Figure 5. HOMO LUMO Diagram Figure 6. Raman Spectra (190.7 and 182.2) and methyl (22.0, benzylic) carbons. This inferred that there were two aromatic nuclei that were joined through two carbonyl carbons. Thus, an anthraquinone. It can be suggested again that one of the aromatic nuclei of this an- thraquinone contains a methyl and a hydroxyl substituent and the other contains two, hydroxyl substituents, one at position 8 and the other at 6. Using 2D NMR spectra Correlation (COSY), Heteronuclear Single Quantum Correlation (HSQC) and Heteronuclear Mul- tiple Bonds Correlation (HMBC), emodin was identified as (1, 6, 8-trihydroxy-3-methylemodin), which is an anthraquinone. Both 1D and 2D NMR spectra and also a comparison of the structure of the isolated molecule with literature values of same compound isolated from other plants like Rumex japonica, fur- ther confirmation was alluded to [21, 12 &13]. Table 3. 1H NMR (400 MHz, DMSO solvent) Position chemical shift (δ) ppm (J in Hz) multiplicity 1 - - 2 7.20 1H, m 3 - - 4 7.53 (1.57) 1H, d 5 6.62 (2.40) 1H, d 6 - - 7 7.14 (2.39) 1H, d 8 - 9 - - 10 - - 11 - - 12 - - 13 - - 14 - - 3-CH3 2.43 3H, s 1-OH 2.06 1H, s 8-OH 12.12 1H, s 6-OH 11.30 1H,s Table 4. 13C NMR Result (DMSO) Position Chemical shift (δ) type of C 1 161.8 C 2 124.6 CH 3 148.7 C 4 121.0 CH 5 108.4 CH 6 166.2 C 7 109.5 CH 8 164.9 C 9 190.7 C 10 182.2 C 11 113.9 C 12 133.4 C 13 108.5 C 14 135.7 C 3-CH3 22.0 CH3 1H and 13C (NMR) of the spectra were recorded on NMR machine: JEOL-LA-400 MHz FT-NMR spectrophotometer, at SIPBS, University, Strathclyde, Glasgow, United Kingdom, us- ing deuterated solvents as indicated by Tables 3 and 4. 3.3. Bond Distances and Bond Angles Figure 4 is the optimized geometry of Emodin showing the atomic numbers. These numbers help in determining the 364 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 365 distance between two atoms (say atoms 3 and 5) and the angles between atoms. Table 6 of the supporting information contains the complete bonds distances (in Angstrom) and bond angles (in degrees), of Emodin isolated from the methanol extract. 3.4. Homo- Lumo Diagram Here electron flow, shows whether there is constructive overlap / bonding interaction, or not, between the orbital of the HOMO and those of the LUMO. It also indicates that the orbitals are either occupied or unoccupied, Table 9 and Figure 5. When the overlap is favourable, electron movement is symmetry allowed. The computational calculations have validated the theory of this interaction. 3.5. Raman Spectra This provided good information about the structure of emodin. In this write up, the phase and the polymorphy, crystalline and molecular interactions of the atoms were computed and they tallied with the theory. (See Figure 6 and Table 10). Table 5: IR Values (Frequencies: CM−1 and their intensities) Frequency, cm−1 IR Intensity 40.5889 1.7505 58.1541 0.1401 72.4885 0.1147 123.9918 3.1669 152.1424 2.1859 180.5744 0.4699 185.0588 1.6663 255.505 3.307 256.5763 0.0736 277.7802 4.6633 294.7906 0.2492 297.6356 2.5751 351.015 0.4827 366.8926 1.6488 382.5217 190.7134 400.1286 9.5094 420.2978 0.9179 464.6792 34.443 477.8178 16.8814 505.9458 1.3444 520.2946 9.4524 557.7997 4.895 605.0876 14.3639 606.812 13.8679 613.2264 0.8377 652.8296 4.129 665.3268 23.4006 686.8013 28.6752 701.3117 10.2161 717.2705 0.6281 737.3912 2.1851 744.8034 9.2651 772.1549 283.7709 786.5867 5.1204 806.2587 84.9909 844.6811 86.8029 845.4904 24.5256 949.8981 67.5742 Continued on next page 365 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 366 Table 5 – Continued from previous page Frequency, cm−1 IR Intensity 980.7929 33.8411 991.5636 66.5423 1008.3375 5.9754 1019.5568 2.2067 1063.7093 1.3686 1087.4272 13.171 1110.4729 52.0946 1138.1731 32.1339 1196.3708 5.8936 1205.8194 206.5051 1230.0187 7.0492 1253.0616 123.2033 1291.437 224.8896 1294.8107 424.9948 1311.5505 92.2745 1348.5262 102.8252 1393.5713 71.2756 1400.046 119.8228 1440.4723 349.6365 1449.158 118.6796 1486.7681 127.3453 1504.6975 67.6164 1515.7165 664.1199 1563.6894 1.0644 1577.6142 7.1853 1599.795 7.4221 1627.5681 97.4458 1640.3534 10.8432 1642.8372 63.6547 1660.0202 41.9661 1725.1233 26.9024 1743.1457 155.4465 1779.4404 42.6281 1800.8258 161.4526 1805.9447 688.232 1858.3537 0.0332 3168.3115 25.498 3223.758 22.4323 3253.8947 25.0516 3375.7378 3.6376 3377.4741 1.6247 3378.858 5.0178 3411.1628 0.2215 3907.6476 236.8743 3914.4907 145.2159 4084.1357 117.2641 Structural illustrations of Bond Distance and Bond Angles Table 6: Numerical values of bond distances and Angles R(1-2) 1.405 Continued on next page 366 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 367 Table 6 – Continued from previous page R(1-8) 1.387 R(1-19) 1.349 R(2-3) 1.457 R(2-4) 1.405 R(3-7) 1.460 R(3-20) 1.251 R(4-5) 1.487 R(4-9) 1.373 R(5-6) 1.482 R(5-10) 1.221 R(6-7) 1.410 R(6-11) 1.370 R(7-12) 1.395 R(8-18) 1.374 R(8-21) 1.066 R(9-18) 1.395 R(9-22) 1.069 R(11-14) 1.405 R(11-15) 1.069 R(12-13) 1.396 R(12-16) 1.352 R(13-14) 1.375 R(13-17) 1.069 R(14-27) 1.505 R(16-25) 0.954 R(18-23) 1.364 R(19-24) 0.954 R(23-26) 0.946 R(27-28) 1.082 R(27-29) 1.082 R(27-30) 1.079 R(20-24) 1.828 R(20-25) 1.834 A(2-1-8) 120.5 A(2-1-19) 123.3 A(1-2-3) 121.1 A(1-2-4) 118.2 A(8-1-19) 116.2 A(1-8-18) 119.8 A(1-8-21) 119.5 A(1-19-24) 113.6 A(3-2-4) 120.7 A(2-3-7) 119.6 A(2-3-20) 120.2 A(2-4-5) 120.3 A(2-4-9) 121.4 A(7-3-20) 120.1 A(3-7-6) 120.8 A(3-7-12) 121.1 A(3-20-24) 105.4 A(3-20-25) 105.5 A(5-4-9) 118.3 A(4-5-6) 118.4 Continued on next page 367 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 368 Table 6 – Continued from previous page A(4-5-10) 120.4 A(4-9-18) 119.1 A(4-9-22) 119.4 A(6-5-10) 121.2 A(5-6-7) 120.1 A(5-6-11) 118.8 A(7-6-11) 121.1 A(6-7-12) 118.1 A(6-11-14) 120.5 A(6-11-15) 118.9 A(7-12-13) 120.2 A(7-12-16) 123.9 A(18-8-21) 120.7 A(8-18-9) 121.1 A(8-18-23) 117.2 A(18-9-22) 121.5 A(9-18-23) 121.7 A(14-11-15) 120.6 A(11-14-13) 118.7 A(11-14-27) 119.9 A(13-12-16) 115.9 A(12-13-14) 121.3 A(12-13-17) 117.1 A(12-16-25) 113.5 A(14-13-17) 121.6 A(13-14-27) 121.4 A(14-27-28) 110.8 A(14-27-29) 110.8 A(14-27-30) 111.4 A(16-25-20) 135.9 A(18-23-26) 115.2 A(19-24-20) 136.3 A(28-27-29) 107.5 A(28-27-30) 108.1 A(29-27-30) 108.1 A(24-20-25) 149.1 W1(A) 40.6 W2(A) 58.2 W3(A) 72.5 W4(A) 124.0 W5(A) 152.1 W6(A) 180.6 W7(A) 185.1 W8(A) 255.5 W9(A) 256.6 W10(A) 277.8 W11(A) 294.8 W12(A) 297.6 W13(A) 351.0 W14(A) 366.9 W15(A) 382.5 W16(A) 400.1 W17(A) 420.3 Continued on next page 368 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 369 Table 6 – Continued from previous page W18(A) 464.7 W19(A) 477.8 W20(A) 505.9 W21(A) 520.3 W22(A) 557.8 W23(A) 605.1 W24(A) 606.8 W25(A) 613.2 W26(A) 652.8 W27(A) 665.3 W28(A) 686.8 W29(A) 701.3 W30(A) 717.3 W31(A) 737.4 W32(A) 744.8 W33(A) 772.2 W34(A) 786.6 W35(A) 806.3 W36(A) 844.7 W37(A) 845.5 W38(A) 949.9 W39(A) 980.8 W40(A) 991.6 W41(A) 1008.3 W42(A) 1019.6 W43(A) 1063.7 W44(A) 1087.4 W45(A) 1110.5 W46(A) 1138.2 W47(A) 1196.4 W48(A) 1205.8 W49(A) 1230.0 W50(A) 1253.1 W51(A) 1291.4 W52(A) 1294.8 W53(A) 1311.6 W54(A) 1348.5 W55(A) 1393.6 W56(A) 1400.0 W57(A) 1440.5 W58(A) 1449.2 W59(A) 1486.8 W60(A) 1504.7 W61(A) 1515.7 W62(A) 1563.7 W63(A) 1577.6 W64(A) 1599.8 W65(A) 1627.6 W66(A) 1640.4 W67(A) 1642.8 W68(A) 1660.0 W69(A) 1725.1 W70(A) 1743.1 Continued on next page 369 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 370 Table 6 – Continued from previous page W71(A) 1779.4 W72(A) 1800.8 W73(A) 1805.9 W74(A) 1858.4 W75(A) 3168.3 W76(A) 3223.8 W77(A) 3253.9 W78(A) 3375.7 W79(A) 3377.5 W80(A) 3378.9 W81(A) 3411.2 W82(A) 3907.6 W83(A) 3914.5 W84(A) 4084.1 Table 7. Dipole moment (Field –independent Basis, Debye) X 1.9607 Y -3.2319 Z -0.0025 Total 3.7801 Table 8. Rot. Constants for Emodin Rotational Constants GHZ A 0.7462698 B 0.2467690 C 0.1856618 Table 9: Numerical indicators of occupied and unoccupied molecular orbitals 1 -20.6106 Occupied A 2 -20.59061 Occupied A 3 -20.58999 Occupied A 4 -20.58463 Occupied A 5 -20.58063 Occupied A 6 -11.39494 Occupied A 7 -11.38389 Occupied A 8 -11.35976 Occupied A 9 -11.3571 Occupied A 10 -11.35506 Occupied A Continued on next page 370 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 371 Table 9 – Continued from previous page 11 -11.30275 Occupied A 12 -11.29346 Occupied A 13 -11.29192 Occupied A 14 -11.28269 Occupied A 15 -11.28221 Occupied A 16 -11.2699 Occupied A 17 -11.2639 Occupied A 18 -11.26076 Occupied A 19 -11.25788 Occupied A 20 -11.24752 Occupied A 21 -1.45133 Occupied A 22 -1.443 Occupied A 23 -1.43897 Occupied A 24 -1.43163 Occupied A 25 -1.4124 Occupied A 26 -1.21648 Occupied A 27 -1.19863 Occupied A 28 -1.12143 Occupied A 29 -1.07739 Occupied A 30 -1.06499 Occupied A 31 -1.05973 Occupied A 32 -0.9952 Occupied A 33 -0.9526 Occupied A 34 -0.92195 Occupied A 35 -0.89005 Occupied A 36 -0.86663 Occupied A 37 -0.83926 Occupied A Continued on next page 371 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 372 Table 9 – Continued from previous page 38 -0.79888 Occupied A 39 -0.77404 Occupied A 40 -0.76007 Occupied A 41 -0.73987 Occupied A 42 -0.72586 Occupied A 43 -0.69958 Occupied A 44 -0.69417 Occupied A 45 -0.67067 Occupied A 46 -0.66231 Occupied A 47 -0.65235 Occupied A 48 -0.64739 Occupied A 49 -0.63103 Occupied A 50 -0.62251 Occupied A 51 -0.61638 Occupied A 52 -0.60289 Occupied A 53 -0.60155 Occupied A 54 -0.59301 Occupied A 55 -0.58622 Occupied A 56 -0.58475 Occupied A 57 -0.56457 Occupied A 58 -0.56087 Occupied A 59 -0.55885 Occupied A 60 -0.54681 Occupied A 61 -0.54236 Occupied A 62 -0.53297 Occupied A 63 -0.49741 Occupied A 64 -0.48094 Occupied A Continued on next page 372 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 373 Table 9 – Continued from previous page 65 -0.46984 Occupied A 66 -0.44326 Occupied A 67 -0.37943 Occupied A 68 -0.36226 Occupied A 69 -0.35055 Occupied A 70 -0.33995 Occupied A 71 -0.0007 Unoccupied A 72 0.06955 Unoccupied A 73 0.10587 Unoccupied A 74 0.13378 Unoccupied A 75 0.13583 Unoccupied A 76 0.14836 Unoccupied A 77 0.18701 Unoccupied A 78 0.2009 Unoccupied A 79 0.2011 Unoccupied A 80 0.2037 Unoccupied A 81 0.21134 Unoccupied A 82 0.22203 Unoccupied A 83 0.22495 Unoccupied A 84 0.23454 Unoccupied A 85 0.23529 Unoccupied A 86 0.25213 Unoccupied A 87 0.32229 Unoccupied A 88 0.34319 Unoccupied A 89 0.34611 Unoccupied A 90 0.35786 Unoccupied A 91 0.37219 Unoccupied A Continued on next page 373 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 374 Table 9 – Continued from previous page 92 0.3831 Unoccupied A 93 0.4018 Unoccupied A 94 0.40497 Unoccupied A 95 0.41765 Unoccupied A 96 0.43383 Unoccupied A 97 0.44363 Unoccupied A 98 0.44626 Unoccupied A 99 0.45481 Unoccupied A 100 0.46011 Unoccupied A 101 0.48707 Unoccupied A 102 0.49981 Unoccupied A 103 0.50292 Unoccupied A 104 0.50877 Unoccupied A 105 0.51194 Unoccupied A 106 0.52321 Unoccupied A 107 0.52819 Unoccupied A 108 0.53979 Unoccupied A 109 0.54525 Unoccupied A 110 0.55944 Unoccupied A 111 0.56865 Unoccupied A 112 0.57009 Unoccupied A 113 0.58434 Unoccupied A 114 0.58662 Unoccupied A 115 0.59683 Unoccupied A 116 0.60621 Unoccupied A 117 0.60814 Unoccupied A 118 0.61375 Unoccupied A Continued on next page 374 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 375 Table 9 – Continued from previous page 119 0.61988 Unoccupied A 120 0.62327 Unoccupied A 121 0.62597 Unoccupied A 122 0.62776 Unoccupied A 123 0.63742 Unoccupied A 124 0.65303 Unoccupied A 125 0.65887 Unoccupied A 126 0.66405 Unoccupied A 127 0.67701 Unoccupied A 128 0.68162 Unoccupied A 129 0.68987 Unoccupied A 130 0.69117 Unoccupied A 131 0.69598 Unoccupied A 132 0.7286 Unoccupied A 133 0.73459 Unoccupied A 134 0.75046 Unoccupied A 135 0.75306 Unoccupied A 136 0.76128 Unoccupied A 137 0.77724 Unoccupied A 138 0.77807 Unoccupied A 139 0.77996 Unoccupied A 140 0.80091 Unoccupied A 141 0.80389 Unoccupied A 142 0.81138 Unoccupied A 143 0.81625 Unoccupied A 144 0.82077 Unoccupied A 145 0.83575 Unoccupied A Continued on next page 375 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 376 Table 9 – Continued from previous page 146 0.84813 Unoccupied A 147 0.86274 Unoccupied A 148 0.88017 Unoccupied A 149 0.88642 Unoccupied A 150 0.88885 Unoccupied A 151 0.89606 Unoccupied A 152 0.92417 Unoccupied A 153 0.93098 Unoccupied A 154 0.9795 Unoccupied A 155 0.98929 Unoccupied A 156 1.01128 Unoccupied A 157 1.01814 Unoccupied A 158 1.02265 Unoccupied A 159 1.02918 Unoccupied A 160 1.05372 Unoccupied A 161 1.06017 Unoccupied A 162 1.06199 Unoccupied A 163 1.06346 Unoccupied A 164 1.07991 Unoccupied A 165 1.08652 Unoccupied A 166 1.09138 Unoccupied A 167 1.10578 Unoccupied A 168 1.11793 Unoccupied A 169 1.1187 Unoccupied A 170 1.13433 Unoccupied A 171 1.14179 Unoccupied A 172 1.14713 Unoccupied A Continued on next page 376 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 377 Table 9 – Continued from previous page 173 1.16523 Unoccupied A 174 1.17615 Unoccupied A 175 1.1908 Unoccupied A 176 1.19371 Unoccupied A 177 1.20229 Unoccupied A 178 1.21612 Unoccupied A 179 1.25361 Unoccupied A 180 1.26206 Unoccupied A 181 1.27792 Unoccupied A 182 1.29634 Unoccupied A 183 1.34272 Unoccupied A 184 1.36669 Unoccupied A 185 1.37455 Unoccupied A 186 1.38165 Unoccupied A 187 1.39717 Unoccupied A 188 1.45107 Unoccupied A 189 1.48546 Unoccupied A 190 1.49397 Unoccupied A 191 1.50947 Unoccupied A 192 1.51616 Unoccupied A 193 1.54722 Unoccupied A 194 1.55972 Unoccupied A 195 1.62076 Unoccupied A 196 1.92958 Unoccupied A 197 1.9693 Unoccupied A 198 1.99045 Unoccupied A 199 2.01527 Unoccupied A Continued on next page 377 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 378 Table 9 – Continued from previous page 200 2.04241 Unoccupied A 201 2.47872 Unoccupied A 202 2.55557 Unoccupied A 203 2.57245 Unoccupied A 204 2.58411 Unoccupied A 205 2.61213 Unoccupied A 206 2.66724 Unoccupied A 207 2.67833 Unoccupied A 208 2.7261 Unoccupied A 209 2.75184 Unoccupied A 210 2.76667 Unoccupied A 211 2.83591 Unoccupied A 212 2.87279 Unoccupied A 213 2.87898 Unoccupied A 214 2.89883 Unoccupied A 215 2.92545 Unoccupied A 216 2.94814 Unoccupied A 217 2.96326 Unoccupied A 218 2.98075 Unoccupied A 219 3.03619 Unoccupied A 220 3.05634 Unoccupied A 221 3.09158 Unoccupied A 222 3.09641 Unoccupied A 223 3.10212 Unoccupied A 224 3.10332 Unoccupied A 225 3.10964 Unoccupied A 226 3.17293 Unoccupied A Continued on next page 378 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 379 Table 9 – Continued from previous page 227 3.23325 Unoccupied A 228 3.248 Unoccupied A 229 3.29189 Unoccupied A 230 3.30673 Unoccupied A 231 3.32245 Unoccupied A 232 3.34172 Unoccupied A 233 3.35642 Unoccupied A 234 3.35848 Unoccupied A 235 3.37538 Unoccupied A 236 3.37812 Unoccupied A 237 3.38723 Unoccupied A 238 3.41087 Unoccupied A 239 3.46033 Unoccupied A 240 3.48637 Unoccupied A 241 3.502 Unoccupied A 242 3.53895 Unoccupied A 243 3.56422 Unoccupied A 244 3.57188 Unoccupied A 245 3.59923 Unoccupied A 246 3.61431 Unoccupied A 247 3.62728 Unoccupied A 248 3.65106 Unoccupied A 249 3.67652 Unoccupied A 250 3.70142 Unoccupied A 251 3.71733 Unoccupied A 252 3.74714 Unoccupied A 253 3.76852 Unoccupied A Continued on next page 379 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 380 Table 9 – Continued from previous page 254 3.89765 Unoccupied A 255 3.98257 Unoccupied A 256 5.32337 Unoccupied A 257 5.35191 Unoccupied A 258 5.35493 Unoccupied A 259 5.38283 Unoccupied A 260 5.40342 Unoccupied A 261 5.44518 Unoccupied A 262 5.49454 Unoccupied A 263 5.50494 Unoccupied A 264 5.54169 Unoccupied A 265 5.5829 Unoccupied A 266 5.60217 Unoccupied A 267 5.66417 Unoccupied A 268 5.70088 Unoccupied A 269 5.73321 Unoccupied A 270 5.76144 Unoccupied A 271 24.19134 Unoccupied A 272 24.27042 Unoccupied A 273 24.41848 Unoccupied A 274 24.49212 Unoccupied A 275 24.49889 Unoccupied A 276 24.51616 Unoccupied A 277 24.5837 Unoccupied A 278 24.63317 Unoccupied A 279 24.7082 Unoccupied A 280 24.80808 Unoccupied A Continued on next page 380 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 381 Table 9 – Continued from previous page 281 24.81693 Unoccupied A 282 24.83965 Unoccupied A 283 24.88602 Unoccupied A 284 25.00561 Unoccupied A 285 25.02082 Unoccupied A 286 51.55558 Unoccupied A 287 51.58631 Unoccupied A 288 51.59188 Unoccupied A 289 51.59641 Unoccupied A 290 51.60474 Unoccupied A Band gap: 0.33925 A.U Table 10: Frequencies cm−1 and Raman activities Frequency, cm−1 Raman Activity 40.5889 0.0308 58.1541 0.3493 72.4885 0.0255 123.9918 0.0304 152.1424 0.1427 180.5744 1.7709 185.0588 0.3809 255.505 1.9977 256.5763 1.6381 277.7802 0.0179 294.7906 0.6864 297.6356 0.4601 351.015 6.5213 366.8926 1.5406 382.5217 3.5322 400.1286 2.3964 420.2978 1.913 464.6792 0.0432 477.8178 3.0011 505.9458 35.2839 520.2946 2.4177 557.7997 3.7289 605.0876 23.6777 606.812 1.0858 613.2264 1.5184 652.8296 0.7743 665.3268 0.1479 686.8013 1.8993 Continued on next page 381 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 382 Table 10 – Continued from previous page Frequency, cm−1 Raman Activity 701.3117 0.4288 717.2705 0.0411 737.3912 0.1857 744.8034 0.5408 772.1549 0.8902 786.5867 6.7614 806.2587 0.5934 844.6811 0.2227 845.4904 1.5859 949.8981 0.3197 980.7929 0.8345 991.5636 4.1317 1008.3375 1.311 1019.5568 54.1302 1063.7093 0.7049 1087.4272 6.8712 1110.4729 1.8682 1138.1731 3.5729 1196.3708 0.5286 1205.8194 11.7034 1230.0187 26.9241 1253.0616 11.4807 1291.437 9.0978 1294.8107 18.6095 1311.5505 10.9375 1348.5262 55.9278 1393.5713 7.765 1400.046 11.0092 1440.4723 195.2705 1449.158 77.3445 1486.7681 104.1229 1504.6975 44.8716 1515.7165 31.9762 1563.6894 54.3211 1577.6142 15.8238 1599.795 32.9398 1627.5681 30.8732 1640.3534 21.3528 1642.8372 13.7481 1660.0202 9.3907 1725.1233 85.1739 1743.1457 150.3192 1779.4404 106.9382 1800.8258 151.5551 1805.9447 13.6314 1858.3537 221.7421 3168.3115 226.1542 3223.758 93.6794 3253.8947 74.8114 3375.7378 45.7586 3377.4741 59.3447 3378.858 113.9246 Continued on next page 382 Khan et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 360–384 383 Table 10 – Continued from previous page Frequency, cm−1 Raman Activity 3411.1628 138.4204 3907.6476 30.7164 3914.4907 128.1222 4084.1357 128.3823 4. Conclusion This article is the first to have done complete computational and frequency studies on the isolated anthraquinone, “emodin” from P. aquilinum. Optimized geometry, IR frequencies, Bond distances (R) and angles (A), Dipole moments and other parameters have been computationally determined for the isolated molecule from quantum chemical calculations using the GAUSSIAN 09 retinue programs. Experimentally determined and computationally measured IR frequencies agreed perfectly with each other. 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