Applied Chemical Engineering

Design of a novel Schiff base ligand and some of its metal complexes, and DFT/NBO Study; evaluation of the biological activity of a copper (II) complex as an anti-colon cancer agent

Thanaa Abdul Ameer Hilal

Department of Chemistry, College of Education for Women, University of Kufa, Najaf, Iraq

Zainab Jasim Mohammed

Al- Kufa Secondary School for Distinguished Students, General Directorate of Education of Najaf Al-Ashraf, Ministry of Education, Iraq

Mohammed Noaman alanssari

Department of Chemistry, College of Education for Women, University of Kufa, Najaf, Iraq

Hanan Faleh Mohsein

Department of Chemistry, College of Education for Women, University of Kufa, Najaf, Iraq

Nadia Ezzat Al-kirbasee

Department of Chemistry, College of Education for Women, University of Kufa, Najaf, Iraq; College of Engineering, University of Warith Al-Anbiyaa, Karbala, Iraq

DOI: https://doi.org/10.59429/ace.v9i4.6006

Keywords: Schiff base, copper complex, 4-aminobenzamide, colon cancer, HDF, density functional theory, HOMO–LUMO, NBO analysis, ELF analysis

---

Abstract

In this study, a new heterocyclic Schiff base ligand was synthesized from 4-aminobenzamide and indoline-2,3-dione, followed by the preparation of its Cu (II), Zn (II), and Co (II) complexes. The prepared compounds were characterized with the use of different spectroscopic methods, such as FTIR, UV-Vis, 1HNMR, 13CNMR, the melting point determination, and the molar conductivity measurements. The findings indicated that the ligand is a bidentate ligand with nitrogen and oxygen donor atoms to form octahedral metal complexes. The biological activity of the copper (II) complex was tested against human colon cancer cells (HCT116) and normal cells (HDF). The complex had a great inhibitory effect against the cancer cell proliferation, as confirmed by the IC50 values. This shows that the compound under study can be developed in future to be used for pharmaceutical applications. Moreover, the electronic properties of the copper complex were studied by Density Functional Theory (DFT) calculations. The HOMO-LUMO, ELF and NBO analyses revealed the good electronic stability, charge transfer behavior and electron localization around the donor atoms. The findings offer theoretical insight into the electronic characteristics, charge-transfer behavior, and stability of the prepared copper complex, thus facilitating the experimental characterization and biological assessment.

---

References

[1]. Schiff, H., Justus Liebigs Annalen der Chemie. (1864). 131(1): p.p.118-119. https://doi.org/10.1002/jlac.18641310113.

[2]. Alredha, H.M., S.H. Ali, and Mohammed S.S. Baghdad Science Journal. (2022), 19(3): p. 0704-0704. http://dx.doi.org/10.21123/bsj.2022.19.3.0704

[3]. Raczuk, E., Samaszko F. J., Dmochowska B., and Madaj J. Molecules, (2022). 27(3): p.p. 787.

[4]. Bhattacharyya NK, Dutta D, Biswas J. A review on synthesis and biological activity of Schiff Bases. Indian J Chem B. (2021);60(11):1478-1489.

[5]. Al-Mulla, A review: Biological importance of heterocyclic compounds, Der. Pharma. Chem., (2017),9(13), 141–147.

[6]. M.H. Hamzah, S. Eavani, E. Rafiee, CoAl₂O₄/TiO₂ nano composite as an anti-corrosion pigment, Mater Chem. Phys. 242 (2020) 122495. https://doi.org/10.1016/j.matchemphys.2019.122495

[7]. S.M. Alsafy, N.A. Alrazzak, Synthesis characterization and biological activity study of new heterocyclic compounds, Presented at the International Conference on Recent Advances in Science and Engineering (2023) Oct 4-5; Dubai, United Arab Emirates. https://doi.org/10.3390/engproc2023059178.

[8]. Liu Z, He W, Guo Z. Metal coordination in photoluminescent sensing. Chem Soc Rev. (2013);42(4):1568-1600.

[9]. E. Rafiee, M.H. Hamzah, S. Eavani, A novel NTiO2@CoAl2O4-H nanocomposite semiconductor: Study of electrochemical behavior and its relationship with photocatalytic performance, Optik., (2020) 203:163915. https://doi.org/10.1016/j.ijleo.2019.163915.

[10]. M. Sönmez, İ. Berber, E. Akbaş, Synthesis antibacterial and antifungal activity of some new pyridazinone metal complexes, Eur. J. Med. Chem., 41(1) (2006) 101–105.

[11]. A. Al-Ajili, S. Karim, Synthesis and characterization of new bis Schiff base derivatives based on adamantane and evaluation antioxidant activity, Eurasian Chem. Commun., 5(8) (2023). https://doi.org/10.22034/ecc.2023.395623.1630.

[12]. R. Katwal, H. Kaur, B.K. Kapur. Applications of copper—Schiff’s base complexes: A review, Sci. Rev. Chem. Commun., 3 (2013) 1–15.

[13]. S.J. Hoseyni, M. Manoochehri, M.D. Asli, A novel Copper (II) Schiff base complex: Synthesis, characterization, and antibacterial activity, Chem. Res. Lett., 5(4) (2022) https://doi.org/10.22034/ crl.2022.168076.

[14]. R. Deo, C. Kumar, Synthesis and spectral characterization of binuclear compounds of Cu (II) and Ni (II) Schiff base of 2-Hydroxy-5-methylacetophenone and 1,2-Propylenediamine with alkali metal salts of trinitrophenol, J. Chem. Lett., 4(2) (2023). https://doi.org/10.22034/jchemlett.2023.389770.1109.

[15]. M.A. Phaniband, S.D. Dhumwad. Synthesis, characterization and biological studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff bases derived from 4-substituted carbostyrils [Quinolin-2(1H)-ones]. Trans. Met Chem. 32(8) (2007) 1117–1125. https://doi.org/10.1007/s11243-007-0295-2.

[16]. Tabassum, S., Zaki, M., Afzal, M. and Arjmand, F. (2013) Dalton Transactions. 42(27): p.p. 10029-10041. https://doi.org/10.1039/C3DT50646K.

[17]. Zampakou, M., Sofia Balala, Perdih F., Kalogiannis S., Turelc I. and P. George., RSC Advances. (2015). 5(16): p.p. 11861-11872. https://dio.org/10.1039/C4RA11682H.

[18]. Borreg, P., Cardenas, D., Ospina, F., Coy, E. and Quiroga, D., Journal of Fungi. (2023), 9(1): p.p. 113. https://doi.org/10.3390/jof9010113.

[19]. Al-Jumaili M., and Abid M., (2023), Tetrahedron Letters. 124: p.p. 154588.

[20]. Maldonado CR, Salassa L, Gómez-Blanco N, Mareque-Rivas JC. Nano-functionalization of metal complexes for molecular imaging and anticancer therapy. Coord Chem Rev. (2013);257(19-20):2668-2688.

[21]. Suzuki H, Kakigano T, Tada K, Igarashi M, Matsubara K, Inagaki A, Oshima M, Takao T (2005) Synthesis, structures, and reactions of coordinatively unsaturated trinuclear ruthenium polyhydrido complexes, {Ru(C5Me5)}3(μ-H)6 (Y = BF4, CF3SO3, 1/2(SO4), C6H5CO2, CH3CO2, B(C6H5)4, PF6) and [{Ru(C5Me5)}3(μ H)3(μ3-H)2]. Bull Chem Soc Jpn 78:67–87. https:// doi. org/ 10. 1246/ bcsj. 78. 67

[22]. Shima T, Sugimura Y, Suzuki H (2009) Heterometallic trinuclear polyhydrido complexes containing ruthenium and a group 9 metal, [Cp *3Ru2M(μ3-H)(μ-H) 3] (M = Ir or Rh; Cp* = η5-C 5Me5).

[23]. Lee C, Yang W, Parr RG (1988) Development of the Colle–Salvetti correlation-energy formula into a functional of the electron density. Phys Rev B 37:785–789. https:// doi. org/ 10. 1103/ PhysR evB. 37. 785

[24]. Perdew JP (1986) Density-functional approximation for the correlation energy of the inhomogeneous electron gas. Phys Rev B 33:8822–8824. https:// doi. org/ 10. 1103/ PhysR evB. 33. 8822

[25]. Yu, J., Hsu, C.-P., & Head-Gordon, M. (2022). Describing chemical reactivity with frontier molecular orbitals. JACS Au, 2(6), 1383–1394. https://doi.org/10.1021/jacsau.2c00085.

[26]. Gatti C, Lasi D (2007) Source function description of metal-metal bonding in d-block compounds. Faraday Discuss 135:55–78. https:// doi. org/ 10. 1039/ b6054 04h

[27]. Halim, S. A., El-Meligy, A. B., El-Nahas, A. M., & El-Demerdash, S. H. (2024). DFT study and natural bond orbital (NBO) population analysis of 2-(2-hydroxyphenyl)-1-azaazulene tautomers and their mercapto analogs. Scientific Reports, 14, 219. https://doi.org/10.1038/s41598-023-50660-w (Nature)

[28]. -Benesperi, I., Michaels, H., & Freitag, M. (2020). Copper coordination complexes for energy-relevant applications. Energies, 13(9), 2198. https://doi.org/10.3390/en13092198

[29]. R. Mahmoud, A. M. Hammam, S. A. El-Gyar, and S. A. Ibrahim; Monatshefte für Chemie., (1986),117, 313.

[30]. M. Ali, M. Hamzah, I. K. Jebur, and A. K. Ahmed, “Synthesis, Characterization and Biological Activity Evaluation of Some New Azo Derivatives from 2- Amino Benzothiazole and Their Derivatives,” (KUJSS), (2018), vol. 13, no. 1, pp.212-227.

[31]. Gul, S., Maab, S., Rafiq, H., Alam, A., Rehman, M. U., Assad, M.,... & Khan, M. Exploring Bis-Schiff Bases with Thiobarbiturate Scaffold: In Vitro Urease Inhibition, Antioxidant Properties, and In Silico Studies. Russian Journal of Bioorganic Chemistry, (2024), 50(5), 1627-1638.

[32]. Hussein, K. A., Shaalan, N., & Faeq, M., Microwave-Assisted Preparation, Characterization, and Biological Activities of Schiff Bases Derived from 4-Aminoantipyrine with Acetonyl Acetone for Some New Rare-Earth Metals. Indonesian Journal of Chemistry, (2024), 24(5), 1470-1480.

[33]. Aljamali, N. M., Al-Zuhairi, A. J., Rasool, S. R., & Ameerghafil, R. A. Preparation of Organic Compounds by Microwave Technique with Applications. Journal of Modern Chemistry & Chemical Technology, (2025), 16(02), 2.‏

[34]. AL-Adilee, K. J. K., & Hassan, H. M., Preparation, Spectroscopic Characterization and Study of Biological Activity as Anticancer of Some Compounds Using A New Azo-Schiff Base Ligand (N, N, O) Derived From 2-amino-5-methyl Thiazol. International journal of health sciences, (2022),6(S4), 12002-12019.

[35]. Mermer, A., Tüzün, B., Daştan, S. D., & Çevik, Ö. Synthesis of novel Cu (II) complexes with N2O2 ligands: Characterization, theoretical calculations, antimicrobial, antioxidant, DNA binding, and in vitro anticancer activity studies. Polyhedron, (2023), 242, 116487.‏

[36]. Kumari, B., & Ahmad, K. Barbituric acid‐derived azo dye metal complexes: Synthesis, characterization, DFT, and antimicrobial analysis: Applied Organometallic Chemistry, (2024), 38(7), e7525.‏

[37]. Jirjees, V. Y., & Al–Hamdani, A. A. S. Synthesis, characterization and evaluation of anticancer and antioxidant activity of new azo dye derivatives from tryptamine and complexes. Bulletin of the Chemical Society of Ethiopia, (2025), 39(7), 1317-1334.‏

[38]. Zhao, H. N., Hu, X., Tian, Z., Gonzalez, M., Rideout, C. A., Peter, K. T.,... Kolodziej, E. P., Transformation products of the tire-rubber antioxidant 6PPD in heterogeneous gas-phase ozonation: identification and environmental occurrence. Environmental Science & Technology, (2023), 57(14), 5621- 5632.

[39]. Saeed, F. T., & Jasim, Z. U., Synthesis and characterization of new mn (ii), co (ii), ni (ii), cu (ii), zn (ii) and cd (ii) complexes with [(z)-3 ((6-aminopyridine-2-yl) imino) indolin-2-one] ligand. Kimya Problemleri (2024), 22(1), 103-114.

[40]. A.B.P. Lever, Inorganic Electronic Spectroscopy, Elsevier, Amsterdam, 395 (1968); C. K. Jorgenson, Acta Chem., Scand. Nutal and D. W. A. Sharp, J. Inorg. Nucl. Chem., (1964), 26: 1895.

[41]. Noor, S. S., & Kareem, I. K., A bio-scientific study of the new gold complex as an anti -breast cancer agent, as well as its preparation, Molar Conductivity, and Spectral identification of some other metal complexes—Journal of Kufa for Chemical Sciences, (2024), 3(3), 201- 222.

[42]. J.J. Rios, M.C. Reico and A. Vllar, "Antimicrobial screening of natural products", J.Enth.Pharmace, (1988),l23,127-149.

[43]. Kurdy, R. N., & Kareem, I. K., Synthesis, Characterization and study of molecular docking of a new Azo-Schiff base ligand with its metal complexes. Journal of Kufa for Chemical Sciences, (2024), 3(3), 68-85.

[44]. Hilal, T. A. A., & Kareem, I. K., Synthesis of some metal complexes with new heterocyclic ligand (5-(((2-(3-(1 h-indol-3-yl) acryloyl) phenyl) amino) methylene)-2-thiooxodihydropyrimidine-4, 6 (1 h, 5 h)-dione) and their biological effectiveness as antioxidant and anti-cancer. Indones. J. Chem, (2024) 10, 20-130.‏

[45]. TUSHAR S. U., SANJAY K. P. and JYOTSNA G. P, Co(II), Ni(II), Cu(II) and Zn(II) Metal Complexes of Hydrazone Schiff Base Ligand:Synthesis, Characterization, Thermal Behavior, Antioxidant and Antimicrobial Studies. Asian Journal of Chemistry; (2024). Vol. 36, No. 8, 1781-1792.

[46]. Jawad, S. H., & Al-Adilee, K. J., Synthesis, spectroscopic characterization and biological activities as an anticancer and antioxidant of the Pd (II) and Pt (IV) complexes with a new azo dye ligand derived from 5-methyl imidazole. Journal of Molecular Structure, (2023), 1277, 134846. 206-

[47]. Bashandy,M.S.,Mohamed,F.A.,El-Molla,M.M.,Sheier,M.B. and Bedair,A.H. Open.J.Med.Chem, (2016),6,18-35.

[48]. Schuur JH, Selzer P, Gasteiger J. The coding of the three-dimensional structure of molecules by molecular transforms and its application to structure-spectra correlations and studies of biological activity. J Chem Inf Comput Sci. (1996),36(2):334-344.

[49]. G. Mishra, P. K. Dwivedi, N. Verma, S. Srivastava, and A. K. Singh, “Copper Nitrate Catalyzed Synthesis Of Novel Thiazolyl Hydrazones: Anti-Inflammatory Effect Via COX-2 / IL-6 Dual Antagonistic Action,” Journal Pharm. Negat. Results, vol. (2022),13, no. 10, pp. 3821–3833.

[50]. Al-Hamdani, A. A.S, Balkhi, A. M, Falah, A, Shaker, Sh. A. J. Chil. Chem. Soc.(2015), 60 (1): 2774-2785.

[51]. W. J. Geary; Coord Chem Rev, (1971), 7, 81.

[52]. Unavane, S., Patil, R., Syed, S., & Jain, H. K.. Exploring the therapeutic potential of copper and cobalt complexes as anticancer agents: a comprehensive review. Transition Metal Chemistry, (2025), 50(4), 407-430.‏

[53]. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; So DJ (2013) Gaussian 09 Revision D. 01 Release Notes. Gaussian, Inc, Wallingford CT (June):1–13.

[54]. Kadhim NH, Hussain T, Abdulhussein HA (2025) Gallium doped AlP monolayers: A promising architecture for gas sensing. Comput Theor Chem 115301.

[55]. Kadhim NH, Abo Nasria AH, Alhameedi K, Hussain T, Abdulhussein HA (2025) Light Transition Metal Functionalized ψ‐Graphene as Promising Hydrogen Storage Architecture. Advanced Energy and Sustainability Research 2500154.

[56]. Hussein MA, Al-Ameed K, Almansori AK, Owaid NJ (2024) Efficient amide bond formation via tropylium ion organocatalysis. RSC Adv 14(46):34428–34434

[57]. Mohammed MA, Abdulhussein HA, Al-ibadi MAM, Raju RK, Johnston RL (2021) Global minima and structural properties of AuFe nanoalloys from a Mexican Enhanced Genetic Algorithm-based Density Functional Theory. Chem Phys Lett 776:138675.

[58]. becke, A. D. (1993). Density-functional thermochemistry. III. The role of exact exchange. The Journal of Chemical Physics, 98(7), 5648–5652. https://doi.org/10.1063/1.464913.

[59]. Da CJ, Head-Gordon M (2008) Long-range corrected hybrid density functionals with damped atom-atom dispersion corrections. Phys Chem Chem Phys 10:6615–6620. https:// doi. org/ 10. 1039/ b8101 89b

[60]. Fuentealba P, Preuss H, Stoll H, Von Szentpály L (1982) A proper account ocore-polarization with pseudopotentials: single valence-electron alkali compounds. Chem Phys Lett 89:418–422. https:// doi. org/ 10. 1016/ 0009- 2614(82) 80012-2

[61]. Hehre WJ, Ditchfield K, Pople JA (1972) Self-consistent molecu lar orbital methods. XII. Further extensions of Gaussian-type basis sets for use in molecular orbital studies of organic molecules. J Chem Phys 56:2257–2261. https:// doi. org/ 10. 1063/1. 16775 27

[62]. Lindmaa, A., Davidsson, J., Mattsson, A. E., & Armiento, R. (2019). Semi-local parameterization of the electron localization function in second-order density gradients. Physical Review B, 100(14), 144112. https://doi.org/10.1103/PhysRevB.100.144112

[63]. Savin, A., Nesper, R., Wengert, S., & Fässler, T. F. (1997). ELF: The electron localization function. Angewandte Chemie International Edition in English, 36(17), 1808–1832. https://doi.org/10.1002/anie.199718081

[64]. Benesperi, I., Michaels, H., & Freitag, M. (2020). Copper coordination complexes for energy-relevant applications. Energies, 13(9), 2198. https://doi.org/10.3390/en13092198

[65]. Reed, A. E., Curtiss, L. A., & Weinhold, F. (1988). Intermolecular interactions from a natural bond orbital, donor–acceptor viewpoint. Chemical Reviews, 88(6), 899–926. https://doi.org/10.1021/cr00088a005

[66]. Weinhold, F. (1998). Natural bond orbital methods. In P. von R. Schleyer, N. L. Allinger, T. Clark, J. Gasteiger, P. A. Kollman, H. F. Schaefer III, & P. R. Schreiner (Eds.), Encyclopedia of Computational Chemistry (Vol. 3, pp. 1792–1811). Wiley.

[67]. Halim, S. A., El-Meligy, A. B., El-Nahas, A. M., & El-Demerdash, S. H. (2024). DFT study, and natural bond orbital (NBO) population analysis of 2-(2-hydroxyphenyl)-1-azaazulene tautomers and their mercapto analogues. Scientific Reports, 14, 219. https://doi.org/10.1038/s41598-023-50660-w.