N'-(Pyridin-3-ylmethylene)benzenesulfonohydrazide: Crystal structure, DFT, Hirshfeld surface and in silico anticancer studies European Journal of Chemistry 12 (3) (2021) 256-264 European Journal of Chemistry ISSN 2153-2249 (Print) / ISSN 2153-2257 (Online) – Copyright © 2021 The Authors – Atlanta Publishing House LLC – Printed in the USA. This work is published and licensed by Atlanta Publishing House LLC – CC BY NC – Some Rights Reserved. https://dx.doi.org/10.5155/eurjchem.12.3.256-264.2102 European Journal of Chemistry View Journal Online View Article Online N'-(Pyridin-3-ylmethylene)benzenesulfonohydrazide: Crystal structure, DFT, Hirshfeld surface and in silico anticancer studies Ifeyinwa Stella Ozochukwu 1, Obinna Chibueze Okpareke 1, David Chukwuma Izuogu 1, Akachukwu Ibezim 2, Oguejiofo Theophilus Ujam 1 and Jonnie Niyi Asegbeloyin 1,* 1 Department of Pure and Industrial Chemistry, University of Nigeria, Nsukka 410001, Enugu State, Nigeria ifystella47@yahoo.com (I.S.O.), obinna.okpareke@unn.edu.ng (O.C.O.), david.izuogu@unn.edu.ng (D.C.I.), oguejiofo.ujam@unn.edu.ng (O.T.U.), niyi.asegbeloyin@unn.edu.ng (J.N.A.) 2 Department of Pharmaceutical and Medicinal Chemistry, University of Nigeria, Nsukka 410001, Enugu State, Nigeria akachukwu.ibezim@unn.edu.ng (A.I.) * Corresponding author at: Department of Pure and Industrial Chemistry, University of Nigeria, Nsukka 410001, Enugu State, Nigeria. e-mail: niyi.asegbeloyin@unn.edu.ng (J.N. Asegbeloyin). 10.5155/eurjchem.12.3.256-264.2102 Received: 31 January 2021 Received in revised form: 01 April 2021 Accepted: 20 April 2021 Published online: 30 September 2021 Printed: 30 September 2021 A new Schiff base, N'-(pyridin-3-ylmethylene)benzenesulfonohydrazide, was synthesized and characterized by elemental analysis, IR, Mass, 1H NMR and 13C NMR spectroscopy, and single-crystal X-ray determination. The asymmetric molecule crystallized in the monoclinic crystal system and P2(1)/c space group. Crystal data for C12H11N3O2S: a = 9.7547(4) Å, b = 9.8108(4) Å, c = 13.1130(5) Å, β = 109.038(2)°, V = 1186.29(8) Å3, Z = 4, μ(MoKα) = 0.270 mm-1, Dcalc = 1.463 g/cm3, 13338 reflections measured (5.296° ≤ 2Θ ≤ 55.484°), 2790 unique (Rint = 0.0494, Rsigma = 0.0400) which were used in all calculations. The final R1 was 0.0345 (I > 2σ(I)) and wR2 was 0.0914 (all data). In the crystal structure of the compound C12H11N3O2S, molecules are linked in a continuous chain by intermolecular of N∙∙∙HN=N hydrogen bonds. The pyridine moiety is planar, while the benzenesulfonohydrazide group adopts a gauche conformation about C-S-N angle (105.54°). The Hirshfeld surface analysis and fingerprint plots were used to establish the presence, nature, and percentage contribution of the different intermolecular interactions, including N-H∙∙∙N, C-H∙∙∙O, C-H∙∙∙C, and π∙∙∙π interactions, with the C-H contacts having the most significant contribution. The pairwise interaction energies were calculated at the B3LYP/6-31G(d,p) level of theory, and interaction energy profiles showed that the electrostatic forces had the most significant contribution to the total interaction energies of the different molecular pairs in the crystal. In-silico technique was used to examine the compound as a possible anticancer agent. The molecule demonstrated zero violation of the criteria of Lipinski’s rule of five with a polar surface area of 116.03 Å2. The molecule displayed favorable binding interactions with ten selected validated anticancer protein targets ranging from -9.58 to -11.95 kcal/mol and - 2.73 to -5.73 kcal/mol on scoring and rescoring, respectively, with London dG and Affinity dG scoring functions. Two proteins; farnesyl transferase and signaling protein, preferred interactions with the Schiff-base over their co-crystallized inhibitors according to London dG scoring. Analysis of binding poses indicated that the Schiff-base made contact with amino acid residues of the two proteins through the N-H, sulphonyl oxygen, and phenyl groups, and this could be exploited in chemical and structural modification towards activity optimization. Schiff base Crystal structure Hirshfeld surface Carboxaldehyde Anticancer activity Benzenesulfonohydrazide Cite this: Eur. J. Chem. 2021, 12(3), 256-264 Journal website: www.eurjchem.com 1. Introduction N-Heterocyclic Schiff bases and their metal complexes have received considerable attention from researchers for decades because of their exciting coordination chemistry, pharma- ceutical importance, and high biological activity [1-4]. Many Schiff base compounds have been reported to show high response when tested for in vitro and in vivo biological activities [5-7]. The wide range of pharmacological profiles exhibited by Schiff bases includes anticancer activity [6,8-12], anticonvul- sant [13], analgesic, and anti-inflammatory activities [14]. Cancer is caused by an abnormal and uncoordinated growth of a mass of tissue, which continues to multiply after cessation of the stimuli which initiated it [15]. About 7.6 million death amounting to about 13% of all death is caused by cancer per year, and this makes it the second most common disease- related cause of death within the human population [16]. There are reports of rise in cancer cases in spite of all efforts to cope with the menace [17]. Therapeutic options for cancer include the use of radiation, surgery, and drugs [18]. For decades, platinum metal-based drugs have been used for cancer treatment, however, some side effects among which include nephrotoxicity, neurotoxicity, ototoxicity, nausea and vomiting, coupled with observed resistance developed to some of the drugs ABSTRACT RESEARCH ARTICLE KEYWORDS https://dx.doi.org/10.5155/eurjchem.12.3.256-264.2102 https://www.eurjchem.com/ https://dx.doi.org/10.5155/eurjchem.12.3.256-264.2102 mailto:ifystella47@yahoo.com mailto:obinna.okpareke@unn.edu.ng mailto:david.izuogu@unn.edu.ng mailto:oguejiofo.ujam@unn.edu.ng mailto:niyi.asegbeloyin@unn.edu.ng mailto:akachukwu.ibezim@unn.edu.ng mailto:niyi.asegbeloyin@unn.edu.ng http://www.eurjchem.com/ https://crossmark.crossref.org/dialog/?doi=10.5155/eurjchem.12.3.256-264.2102&domain=pdf&date_stamp=2021-09-30 Ozochukwu et al. / European Journal of Chemistry 12 (3) (2021) 256-264 257 2021 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.12.3.256-264.2102 S N H O NH2 O + Reflux N H O CH3OH S O O N H N N + H2O 1 2 3 4 5 6 7 8 9 10 11 12 Scheme 1. Preparation of N'-(pyridin-3-ylmethylene)benzenesulfonohydrazide (PMB). have limited their clinical applications [19-21]. Researchers have continued to search and develop alternative metal-based and nonmetal-based drugs to improve the potential and the effectiveness against cancer. The title compound, N'-(pyridin-3- ylmethylene)benzene sulfonohydrazide is a new Schiff base; herein is reported, its crystal structure and overall confor- mation. The ability of the molecule to interact with validated receptors targeted for cancer treatment using docking methods is also reported. Furthermore, the Hirshfeld surface analysis and fingerprint plots were used to establish the presence, nature, and percentage contribution of the different types of intermolecular interactions in the crystal. 2. Experimental 2.1 Materials and physical methods Benzene sulfonohydrazide and 3-pyridinecarboxaldehyde were used as obtained from Fluka without further purification. All other chemical substances used were reagent grade commercial products. 1H NMR and 13C NMR spectra were acquired on a Bruker 400 MHz spectrometer, using CDCl3 as the solvent. Mass spectra were acquired using a Bruker MicrOTOF ESI-MS spectrometer. Fourier Transform Infrared (FTIR) spectra were recorded in the range of 4000-400 cm-1 as KBr discs on a Perkin Elmer 100 Infrared Spectrophotometer. Melting point ranges were obtained with a Fisher John melting point apparatus. Elemental analyses of C, H and N were performed using a Carlo Erba Elemental analyzer EA1108. The X-ray crystallographic data were obtained at the University of Auckland on a Bruker SMART APEX II diffractometer. 2.2. Synthesis of N'-(pyridin-3-ylmethylene)benzene sulfonohydrazide (PMB) The title compound, N'-(pyridin-3-ylmethylene)benzene sulfonohydrazide, was synthesized as follows: A solution of 3- pyridinecarboxaldehyde (107 mg, 1 mmol) in methanol 10 mL was mixed with a solution of benzene sulfonohydrazide (172 mg, 1 mmol) in methanol, 10 mL. The mixture was refluxed for 3 h, and the resulting solution was cooled to obtain whitish product which was filtered, dried, and recrystallized in methanol (Scheme 1). Crystals suitable for X-ray crystallo- graphic analysis were obtained by slow evaporation of a methanolic solution of the compound at room temperature for 24 h. Color: Colorless. Yield: 89 %. M.p.: 160-162 °C. FT-IR (KBr, ν, cm-1): 3439 (N-H), 1606 (C=N), 1120 (N-N). 1H NMR (400 MHz, CDCl3, δ, ppm): 8.7 (s, 1H, N-H), 8.5 (s, 1H, HC=N), 8.0-7.8 (m, 5H, Ph), 7.4-7.2 (m, 4H, Py). 13C NMR (100 MHz, CDCl3, δ, ppm): 133.63 C1, 129.64 C2, 127.64 C3, 124.41 C4, 127.64 C5, 129.64 C6, 151.20 C7, 139.28 C8, 129.10 C9, 133.73 C10, 144.94 C11, 148.82 C12. ESI-MS (m/z) calcd. [M+Na]+ 284.29, found: [M+Na]+ 284.05; calcd. [M+H]+ 262.31, found [M+H]+ 262.07. Anal. calcd. for C12H11N3O2S: C, 55.16; H, 4.24; N, 16.08. Found: C, 55.46; H, 3.95; N, 15.90 %. 2.3. Crystal structure determination An arbitrary sphere of data were collected on a colorless block-like crystal, having approximate dimensions of 0.400 × 0.220 × 0.200 mm, on a Bruker APEX-II diffractometer using a combination of ω- and φ-scans of 0.5° [22]. Data were corrected for absorption and polarization effects and analyzed for space group determination. The structure was solved by direct methods and expanded routinely [23]. The model was refined by full-matrix least-squares analysis of F2 against all reflections. All non-hydrogen atoms were refined with anisotropic thermal displacement parameters. Unless otherwise noted, hydrogen atoms were included in calculated positions. Thermal para- meters for the hydrogens were tied to the isotropic thermal parameter of the atom to which they are bonded (1.5 × for methyl, 1.2 × for all others). The software SMART was used for the collection of data frames, for indexing reflections, and to determine lattice parameters; SAINT was also used for the integration of the intensity of the reflections and for scaling. SADABS was used for empirical absorption correction. The structure was solved using SHELXS-97 and SHELXL-97 was also used for structure refinement and reporting. The structure was refined by full-matrix least-squares based on Fo2 (SHELXL-97) with anisotropic thermal parameters for non-hydrogen atoms. 2.4. Hirshfeld surface Hirshfeld surfaces (HSs) and corresponding two-dimen- sional fingerprint plots (FPs) were calculated using the Crystal Explorer Software 17.5 [24]. The crystallographic information files (CIF) obtained from the single-crystal X-ray measurements were used for the HS analysis. The Hirshfeld surfaces mapped over dnorm, shape index, and curvedness were generated according to described procedures [25,26], and used for further analysis of the intermolecular interactions in the crystal structure. 2.5. In-silico anticancer study The builder interface implemented in the molecular operating environment (MOE) [27] software was used to generate the three-dimensional chemical structure of the Schiff base energy minimized to a gradient of 0.001 kcal/mol and saved in mol2 format. The following parameters were compu- ted; molar weight (MW), number of rotatable bonds (NRB), hydrogen bond acceptor/donor (HBA/HBD), and lipophilicity (log P), using the molecular descriptor calculator included in the QuSAR module of MOE software. The X-ray crystal structures of all ten protein-targets co-crystallized with their inhibitors were retrieved from the protein databank (PDB codes: 1GS4, 2X9E, 2XMY, 3E37, 3EP2, 3KKP, 3PP1, 4ACM, 4BBG, and 4M8H). The target-ligand complexes were treated according to standard for docking purposes, and the dock protocols were validated following the root mean square deviation (RMSD) method [28]. The dock protocols, which gave conformation of the docked ligands within ≤ 2.00 Å from that of the X-ray crystallized ones were retained and used in docking the Schiff-base into the protein binding sites. The produce receptor-ligand complexes were, respectively, scored and rescored by London dG and Affinity dG scoring methods implemented in the MOE package. 258 Ozochukwu et al. / European Journal of Chemistry 12 (3) (2021) 256-264 2021 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.12.3.256-264.2102 Table 1. Crystal data and structure refinement details for PMB. Empirical formula C12H11N3O2S Formula weight 261.30 Temperature (K) 172(2) Crystal system Monoclinic Space group P21/c a (Å) 9.7547(4) b (Å) 9.8108(4) c (Å) 13.1130(5) α (°) 90 β (°) 109.038(2) γ (°) 90 Volume (Å3) 1186.29(8) Z 4 ρcalc (g/cm3) 1.463 μ (mm-1) 0.270 F(000) 544.0 Crystal size (mm3) 0.400 × 0.220 × 0.200 Radiation MoKα (λ = 0.71073) 2Θ range for data collection (°) 5.296 to 55.484 Index ranges -12 ≤ h ≤ 12, -12 ≤ k ≤ 12, -17 ≤ l ≤ 17 Reflections collected 13338 Independent reflections 2790 [Rint = 0.0494, Rsigma = 0.0400] Data/restraints/parameters 2790/0/167 Goodness-of-fit on F2 1.060 Final R indexes [I≥2σ (I)] R1 = 0.0345, wR2 = 0.0872 Final R indexes [all data] R1 = 0.0411, wR2 = 0.0914 Largest diff. peak/hole (e.Å-3) 0.37/-0.41 Figure 1. Molecular structure of PMB and atoms numbering scheme at 50% probability level for non-H atoms. 3. Results and discussion 3.1. Spectroscopic studies The FTIR spectra of PMB exhibit a strong broad peak at 3439 cm-1, which is ascribed to the intermolecular hydrogen- bonded N-H stretching vibration of the hydrazone moiety. The imine ν(C=N) vibration appeared at 1606 cm-1, similar to frequencies observed in related compounds [29,30]. The characteristic C-H stretches of aromatic groups were found at 3018 cm-1, and ν(N-N) was observed at 1120 cm-1. In the 1H NMR spectra the N-H proton was found at relatively high frequency of δ 8.7 ppm corresponding to a hydrogen-bonded proton. The azomethine proton was also deshielded, and observed at δ 8.5 ppm [5]. The multiplet peak at δ 7.8-8.0 ppm was assigned to the five protons of the phenyl moiety, while the peak at δ 7.2-7.4 ppm was assigned to the pyridinyl protons. The 13C NMR spectra showed ten carbon signals, and these correspond to the molecular formula of PMB. The peak at δ 151.20 ppm was assigned to the (-C=N-) carbon; other assignments are as presented in Section 2.2. The ESI mass spectra of PMB showed molecular ions of [M+Na]+ at m/z 284.05. The [M+H]+ ion is also visible at m/z 262.068. 3.2. Crystal structure description of PMB The molecular structure of PMB with the atom numbering scheme is shown in Figure 1. The compound crystallized as colorless block-like crystals. There are four molecules of the Schiff base in the unit cell of the primitive centrosymmetric monoclinic crystal system, with a space group P2(1)/c. The bond length of C6-N2 is 1.2814(21) Å, indicating the existence of imine C=N in the compound. In the crystal structure, the molecules of the Schiff base C12H11N3O2S, are linked in a continuous chain by an intermolecular hydrogen bond from N3 to N1 of the pyridyl moiety related by the 21-screw axis (Figure 2). This results in a one-dimensional helical chain of H-bond molecules parallel to the b-axis. The pyridine moiety is planar, while the benzensulfonohydrazide group adopts a gauche conformation about C-S-N angle (105.54°). Bond distance and angles within the molecule are as expected. The crystal data and structure refinement details, selected bond lengths and angles, and intramolecular hydrogen bond distances of PMB are summarized in Tables 1-3, respectively. The bond length of N2- C6 (1.281 Å) suggests a double bond character as previously reported for similar compounds [4,31]. The hydrazine N2-N3 bond length of 1.399 Å, shows somewhat double bond characteristics, due to the conjugation between the π electrons on the azomethine group and lone pairs of electrons on N3 [5]. The higher bond length of S1-O2 (1.435 Å) compared to S1-O1 (1.400 Å) can be ascribed to the noncovalent bond interaction between the electronegative oxygen O2-S1 and hydrogen H-C6, which are in closer proximity. The N2-N3 nitrogen atoms adopted the more stable trans-conformation to minimize the steric strain of the substituents. The bond lengths of the pyridine group are all indicative of an aromatic system. However, the bond angle of N1-C1-C2 of 123.40° is higher than expected for sp2 hybridized carbon of 120° because of the conjugation of the nitrogen lone pairs with the π electrons of the aromatic system. The sulphonyl group adopted a distorted tetrahedral geometry, as can be seen from the O1-S1-O2 and O2-S1-N3 bond angles of 120.87 and 104.12°, respectively. This is because of the lone pair of electrons on the sulfur atom as it adopts dsp3 hybridization. Ozochukwu et al. / European Journal of Chemistry 12 (3) (2021) 256-264 259 2021 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.12.3.256-264.2102 Table 2. Selected bond lengths (Å) and bond angles (°) for PMB. Bond lengths (Å) O(1)-S(1) 1.4300(11) N(3)-H(3N) 0.92(2) O(2)-S(1) 1.4346(11) N(3)-S(1) 1.6524(12) C(1)-N(1) 1.3452(19) N(2)-N(3) 1.3987(17) C(1)-C(5) 1.338(2) C(7)-S(1) 1.7636(14) C(1)-H(1) 0.9300 C(6)-N(2) 1.2814(19) C(2)-N(1) 1.3452(19) C(2)-C(3) 1.398(2) Bond angles (°) N(1)-C(5)-C(4) 123.17(14) N(1)-C(1)-C(2) 123.40(13) N(1)-C(5)-H(5) 118.4 N(1)-C(1)-H(1) 118.3 N(2)-N(2)-C(6) 114.74(12) O(1)-S(1)-O(2) 120.87(7) O(2)-S(1)-N(3) 104.12(6) O(1)-S(1)-N(3) 107.76(6) N(2)-C(6)-C(2) 119.95(13) N(2)-N(3)-H(3N) 115.0(13) N(2)-N(3)-S(1) 113.86(9) N(3)-S(1)-C(7) 105.55(6) Table 3. Intramolecular hydrogen bond for PMB. D-H∙∙∙A d(D-H), Å d(H∙∙∙A), Å d(D∙∙∙A), Å ∠(DHA), ° N(3)-H(3N)∙∙∙N(1)#1 0.92(2) 2.00(2) 2.8964(18) 166.3(19) Symmetry transformation used to generate equivalent atoms: #1-x+1, y-1/2, -z+1/2. Figure 2. The packing diagram of PMB shows intermolecular N∙∙∙H-N═N hydrogen bonds as dotted lines. 3.3. Hirshfeld surface analysis The Hirshfeld surface of PMB mapped over the dnorm shows the most intense red regions around the N-H groups resulting from the azomethine-N3-H3···N1 (pyridyl) intermolecular hydrogen bonding interactions (Figure 3a). Apart from the intense red spots from N-H intermolecular contacts, there are a number of other weak intermolecular contacts resulting in the rest of the dnorm surface having white to blue gradient colo- ration. Some of these contacts include phenyl-π···π (pyridyl) interactions depicted as red dotted lines in Figure 3b resulting from C1···C12 and C5···C11 intermolecular contacts. Other intermolecular contacts are the azomethine N-H···π (pyridyl) in red and phenyl-C-H⋯O (sulphonyl) shown as purple lines in Figure 3c and the phenyl-C-H···S (sulphonyl) interactions (Figure 3d). The C-H···π interactions in PMB can also be analyzed by mapping the Hirshfeld surface over the shape index and curvedness surfaces (Figure 4). The donors and acceptors of intermolecular C-H···π contacts are recognized as blue and red regions around the participating atoms [25,26]. The C···H/H···C contacts in a molecule are responsible for the molecular packing in the supramolecular structure and depict the C-H···π interactions [33]. These interactions appear as hollow orange areas (π···H-C) and bulging blue areas (C-H···π) in the compound. The small blue regions surrounding a bright orange spot within the phenyl ring of the PMB molecule are an indication of π⋯π stacking. In addition, the C4-H4···C8 and C8- H8···C4 contacts in pink-colored dotted lines in the shape index mapped isosurface in the molecule (Figure 4a) are typical examples of π⋯π interactions. Further, the flat regions around the phenyl and pyridyl rings on the Hirshfeld surface mapped over curvedness in Figure 4b is another testament to the presence of π···π interactions in the molecule. 3.3.1. Finger print plots The 2-D Fingerprint plots illustrate the overall and percen- tage contributions of the intermolecular contacts in the molecule [32,33]. The overall fingerprint plot for PMB and those delineated into H···N/N···H, H···C/C···H, H···H, H···O/ O···H, and C···O/O···C are illustrated in Figure 5a-f, and their percentage contributions are presented in Table 5. The overall fingerprint plot comprises all intermolecular contacts in the molecule, and this exhibits a shield-like profile with two symmetric spikes on each side of a triangular protrusion (Figure 5a). These spikes are also observed in the fingerprint plots for the N···H/H···N contacts in Figure5b but not in the other surface contacts in Figures 6c-e. This is a clear indication that these spikes are representative of the N3-H3···N1 hydrogen bonding interaction in the crystal structure of the 260 Ozochukwu et al. / European Journal of Chemistry 12 (3) (2021) 256-264 2021 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.12.3.256-264.2102 Table 5. Percentage contribution to intermolecular contacts on the Hirshfeld surface calculated for PMB. Contact Percentage contribution (%) H···N/N···H 15.6 H···C/C···H 26.3 H···H 29.9 H···O/O···H 23.1 C···O/O···C 3.1 C···C 2.0 (a) (b) (c) (d) Figure 3. Hirshfeld Surface interactions mapped over d-norm show (a) the main dark red spots on the molecule showing azomethine-N-H···N (pyridyl hydrogen bonding interactions, (b) Phenyl-π···π (pyridyl), (c) azomethine N-H···π (pyridyl) in red and phenyl-C-H···O(sulphonyl)in purple lines, (d) phenyl- π···O (sulphonyl) and phenyl-C-H···S (sulphonyl) purple lines. (a) (b) Figure 4. The Isosurface representation mapped over the shape index and curvedness isosurfaces. compound and contributes about 15.6% to the overall intermolecular surface contacts in the molecule. The other major surface contacts in the molecule are the C···H/H···C (26.2%), H···H (29.9%), H···O/O···H (23.0%), and C···O/O···C (3.0%), showing that C1-H1⋯O2 intermolecular interactions contribute a combined total of 56.1 % to the overall surface contact in the molecule making it the most significant set of interactions in the crystal lattice. The fingerprint plots also show uneven distribution between the internal (i.e., the donor or acceptor atoms internal to the surface) and the external (i.e., the donor or acceptor atoms external to the surface). The H···N/N···H, H···O/O···H and C···O/O···C contacts are all inclined towards the (internal)-N···H (external) 8.7%, (internal) O···H (external) 12.6%, (internal) C···O (external) 1.8% and (internal) C···H (external) with a slightly higher inclination at 15.3%. These results are slightly different from the distributions reported for N,N-bis–(pyridine-4-ylmethyl) ethane diamine [32]. 3.3.2. Interaction energy calculations The interaction energies between pairs of molecules within the crystal of PMB were calculated by adding up the four energy components comprising of the electrostatic (Eele), polarization (Epol), dispersion (Edis), and exchange repulsion (Erep) [24]. Ozochukwu et al. / European Journal of Chemistry 12 (3) (2021) 256-264 261 2021 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.12.3.256-264.2102 Table 6. A summary of the calculated interaction energies for PMB (kJ/mol). Contact Symmetry R Eele Epol Edis Erep Etot O2-H6 x, -y+1/2, z+1/2 7.00 -11.5 -3.9 -29.5 19.5 -28.7 C5-H11 -x, -y, -z 9.32 -6.5 -2.3 -14.1 9.3 -15.1 H12-H12 x, y, z 9.81 -1.8 -1.0 -17.7 14.3 -9.2 N1-N3 -x, -y, -z 6.21 -36.2 -8.5 -30.3 34.4 -49.7 H9-O1 x, -y+1/2, z+1/2 9.85 -2.5 -1.8 -11.4 5.2 -10.6 C3H3-N -x, y+1/2, -z+1/2 7.17 -52.7 -13.2 -31.5 71.1 -49.0 O2-H1 -x, y+1/2, -z+1/2 6.91 -16.1 -5.3 -26.8 17.9 -33.3 H10-C4 -x, -y, -z 10.81 2.7 -0.3 -1.7 0.0 1.2 O2-H6 -x, -y, -z 8.76 8.6 -1.0 -1.9 0.0 6.7 C4-C10 -x, -y, -z 8.28 2.5 -1.8 -21.6 12.8 -9.5 Figure 5. 2-Dimensional Fingerprint plot of the main intermolecular interactions and contacts in the crystal structure of PMB. The energies were obtained by calculating the wave function of each pair of molecules or atoms at the B3LYP/6- 31G(d,p) level of theory [34]. Quantitative estimations of the strength and nature of the intermolecular interactions in PMB crystal with individual energy components (Eele, Epol, Edis, and Erep) as well as the sum of the energy components Etot are presented in Table 6. The table shows that the electrostatic and dispersive components make the most significant contribution to the total interaction energy profile in the crystal structure. The N3-H3-N hydrogen bonding interaction between the azomethine and pyridyl ring has the most significant total interaction energies. The O2-H6, O2-H1, and O1-H9 short contacts from the intermolecular C-H···O interactions are the next in line with considerable interaction energies. The C-H and C-C and H-H contacts are at the bottom of the energy ladder compared to the other interactions in the crystal lattice. A graphical representation of the magnitude of the interaction energies is presented in Figure 6a-d in the form of an energy framework to show the crystal supramolecular architecture using cylindrical poles joining the centroids of molecular pairs. The red, green, and blue color-coded frameworks in 6a, 6b, and 6c respectively, represent Eele, Edis, and Etot energy components for intermolecular interactions in PMB crystal, while 6d is the annotated Etot energy. The magnitude of the cylindrical pipes indicates the significance of the Eele energy component to the total interaction energy and molecular packing in the crystal. 3.4. In-silico anticancer studies PMB was investigated for its ability to bind to ten validated selected anticancer drug targets. To determine its pharma- cokinetic profile as a potential drug candidate, the Lipinski rule 262 Ozochukwu et al. / European Journal of Chemistry 12 (3) (2021) 256-264 2021 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.12.3.256-264.2102 Table 7. Dock protocols and the corresponding binding free energies and RMSDs. PDB codes Origin of grid box Radius of grid box London dG Affinity dG x y z x y z Score (kcal/mol) RMSD (Å) Score (kcal/mol) RMSD (Å) 1GS4 0.64 31.23 4.73 5.21 5.64 2.92 -26.92 1.07 -23.48 1.03 2X9E 8.05 -20.58 -1.06 9.00 9.89 7.00 -12.78 2.57 -7.95 2.00 2XMY 22.24 -29.27 14.77 1.94 6.03 5.73 -14.10 1.52 -12.47 1.05 3E37 16.99 -73.56 3.73 8.06 7.28 5.64 -4.58 1.98 -4.68 2.01 3EP2 12.00 33.00 19.00 8.00 3.00 4.00 -7.25 2.80 -6.99 1.18 3KKP 18.32 4.17 4.75 6.28 7.19 4.03 -5.68 1.67 -5.37 1.82 3PP1 -32.22 29.88 5.33 6.30 6.83 3.96 -15.95 1.47 -16.43 1.37 4ACM 2.42 27.02 8.45 6.08 7.49 5.48 -15.68 1.25 -13.47 1.09 4BBG 15.20 33.50 -26.50 5.20 4.40 4.30 -13.39 1.69 -12.72 1.88 4M8H 62.98 47.16 30.87 7.37 2.70 4.70 -20.73 1.18 -19.93 1.31 Table 8. Docking results of PMB towards the ten anticancer protein targets. Protein targets PDB codes Scoring London dG (kcal/mol) Rescoring affinity dG (kcal/mol) Androgen receptor 1GS4 -11.28 -5.73 Mitotic regulator for chromosomal alignment and segregation 2X9E -10.35 -3.43 Cyclin-dependent kinase (CDK) responsible for regulating transcription 2XMY -11.72 -3.58 Protein farnesyltransferase 3E37 -10.21 -3.74 Human protein kinase 3EP2 -10.78 -2.73 Signaling protein 3KKP -11.11 -3.72 RAS-RAF-mitogen activated protein kinase/extracellular signal-regulated kinase 3PP1 -11.44 -3.90 Glycogen synthase kinase 4ACM -10.95 -3.95 Cell cycle regulator, critical for the assembly of the mitotic spindle 4BBG -9.88 -4.89 Retinoid X nuclear receptor 4M8H -9.58 -4.32 (a) (b) (c) (d) Figure 6. (a) Electrostatic force, (b) dispersion force (c) total energy (d) annotated total energy framework. The cylindrical radii are proportional to the relative strength of the corresponding energies and were all adjusted to the same scale of 90 with a cutoff value of 5 kJ/mol within 4×4×4-unit cells. of five [36] was used to examine the drug likeness of the molecule and the results showed an excellent oral bio- availability profile: MW = 263.32 Da, log P = 1.45, NRB = 5.00, HBA = 5.00, and HBD = 2.00. The molecule violated none of the criteria of the rule, and possessed an impressive polar surface area (TPSA) of 116.03 Å2. PMB capability as potential anti- cancer agent was assessed by means of docking studies using DockTool in MOE. Docking protocols shown in Table 7, reproduced X-ray crystallography co-crystallized ligand confor- mations within acceptable regions and therefore were employed in docking PMB into the binding sites of the ten studied receptors. Results from both London dG and Affinity dG scoring functions indicated that PMB demonstrated a binding affinity for each of the studied anticancer protein targets in the range of -9.58 to -11.72 kcal/mol and -2.73 to -5.73 kcal/mol, respectively (Table 8). London dG scored the binding interac- tions of PMB with farnesyl transferase, human protein kinase, Ozochukwu et al. / European Journal of Chemistry 12 (3) (2021) 256-264 263 2021 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.12.3.256-264.2102 (a) (b) Figure 7. Binding poses of PMB towards (a) protein farnesyltransferase and (b) signaling protein binding sites. and signaling protein higher than their co-crystallized ligands whereas Affinity dG ranked all co-crystallized ligands higher than PMB. The interesting binding affinities demonstrated by PMB suggest that it could inhibit those enzymes in vitro and possibly prove poisonous to cancerous cells in a biological assay. The molecule could be developed into either farnesyl transferase or signaling protein inhibitor because it outper- formed known inhibitors of the two enzymes, which are greatly importance in cancer [36,37]. Close examination of the molecule’s binding modes to both metalloenzymes (farnesyl transferase and signaling protein) revealed that it bound through its NH sulphonyl oxygen atom and phenyl group. Hydrogen bonds between the sulphonyl oxygen atom and Arg102, NH and Arg89 and the π-π contact between phenyl group and Phe131 could account for the significant interaction of PMB with farnesyl transferase (Figure 7a). Docking calculation by MOE DockTool identified the unique binding pose of PMB in the signaling active protein cavity. Unlike in farnesyl transferase, the magnesium atom at the binding site of the protein was found to make active contribution in the binding interaction of PMB with signaling protein (Figure 7b) and this should be exploited in the chemical structural modification process towards activity optimization. It is noteworthy that the functional units of the compound played a significant role in binding relationship with the amino acid residues at the active site of the metalloenzymes. 4. Conclusion A Schiff base; N'-(pyridin-3-ylmethylene)benzenesulfono hydrazide, was synthesized by reacting equimolar benzene sulfonohydrazide and 3-pyridinecarboxaldehyde. The struc- ture of the compound was confirmed by elemental analysis, spectroscopic techniques (FT-IR, ESI-MS ,1H and 13C NMR) and X-ray crystallography. The compound crystallized in the imine form. Hirshfeld surface analysis indicated the presence of both hydrogen bonding and intermolecular π···π interactions in the supramolecular architecture of the compound, and the results of the calculated pairwise interaction energies showed that the electrostatic forces had the most significant contribution to the total interaction energy of the different molecular pairs in the crystal. In-silico studies revealed that the compound is drug- like, and it made favorable binding interactions with ten selected anticancer drug targets. Moreover, since it showed greater binding affinity for farnesyltransferase and signaling proteins than their co-crystallized ligands and exhibited unique binding interactions with the metalloenzymes’ binding site residues, it merits further attention to develop it into their efficient inhibitors and possibly anticancer agent. Acknowledgments We thank Dr. Tania Groutso (University of Auckland) for collection of the X-ray data sets, the University of Nigeria, Nsukka for infrastructural support. Dr. Fidele Ntie-Kang of the Chemical and Bioactive Information Center, Department of Chemistry, University of Buea, Cameroon is acknowledged for his help with computational tools. Junior Researcher Grant awarded to Akachukwu Ibezim by The African-German Network of Excellence in Science (AGNES) is gratefully acknowledged. Supporting information CCDC-1860214 contains the supplementary crystallo- graphic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by e- mailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44(0)1223-336033. Disclosure statement Conflict of interests: The authors declare that they have no conflict of interest. Author contributions: All authors contributed equally to this work. Ethical approval: All ethical guidelines have been adhered. Sample availability: Samples of the compound is available from the authors. ORCID Ifeyinwa Stella Ozochukwu https://orcid.org/0000-0001-8148-2379 Obinna Chibueze Okpareke https://orcid.org/0000-0003-0815-8198 David Chukwuma Izuogu https://orcid.org/0000-0002-1497-2308 Akachukwu Ibezim https://orcid.org/0000-0003-1620-5716 Oguejiofo Theophilus Ujam https://orcid.org/0000-0002-5628-209X Jonnie Niyi Asegbeloyin https://orcid.org/0000-0002-5710-7613 References [1]. Fonkui, T. Y.; Ikhile, M. I.; Ndinteh, D. T.; Njobeh, P. B. Trop. J. Pharm. Res. 2019, 17 (12), 2507–2518. [2]. Hegazy, W. H. Eur. J. Chem. 2014, 5 (3), 415–418. [3]. Kumar, H.; Chaudhary, R. P. Der Chemica Sinica 2010, 1 (2), 55–56. [4]. Asegbeloyin, J. N.; Ujam, O. T.; Okafor, E. C.; Babahan, I.; Coban, E. P.; Ozmen, A.; Biyik, H. Bioinorg. Chem. Appl. 2014, 2014, 718175. [5]. Asegbeloyin, J. 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Introduction 2. Experimental 2.1 Materials and physical methods 2.2. Synthesis of N'-(pyridin-3-ylmethylene)benzene sulfonohydrazide (PMB) 2.3. Crystal structure determination 2.4. Hirshfeld surface 2.5. In-silico anticancer study 3. Results and discussion 3.1. Spectroscopic studies 3.2. Crystal structure description of PMB 3.3. Hirshfeld surface analysis 3.3.1. Finger print plots 3.3.2. Interaction energy calculations 3.4. In-silico anticancer studies 4. Conclusion Acknowledgments Supporting information Disclosure statement ORCID References PrintField10: PrintField11: PrintField12: PrintField13: PrintField14: PrintField15: PrintField16: PrintField17: PrintField18: PrintField20: PrintField21: PrintField22: PrintField23: PrintField24: PrintField25: PrintField26: PrintField27: PrintField28: