283 This work is licensed under a Creative Commons Attribution 4.0 International License IHJPAS. 37 (2) 2024 Ibn Al-Haitham Journal for Pure and Applied Sciences Journal homepage: jih.uobaghdad.edu.iq PISSN: 1609-4042, EISSN: 2521-3407 Abdullah Sh. Abdullah Alani 1* , Basima Muhsen Sarhan 2 and Vishwa Deepak Tripathi 3 1 Directorate of Institutional Development and Government Coordination, Iraqi Ministry of Education, Baghdad, Iraq. 2 Department of Chemistry, College of Education for Pure Science (Ibn Al–Haitham), University of Baghdad, Baghdad, Iraq. 3 Department of Chemstry, C.M. Science College, Lalit Narayan Mithila University, Darbhanga, Bihar, India. *Corresponding Author. Abstract This study included the preparation and characterization of the new guanine derivative (N- ((6-oxo-6,9-dihydro-1H-purin-2-yl)carbamothioyl)propionamide), with an exciting chemical structure. The guanine part is a bicyclic heterocyclic base that is connected to a carbamothioyl group by a propionamide linker. This nitrogenous base derivative is prepared in two steps: The first step involves the synthesis of propionyl isothiocyanate from the reaction of propionyl chloride with ammonium thiocyanate in acetone. In contrast, the second step consists of the reaction of ammonium thiocyanate with guanine to obtain the ligand. The study also includes the preparation of new complexes of metal ions (Mn +2 , Co +2 , Ni +2 , Cu +2 , Zn +2 , Cd +2 , and Pd +2 ) with a prepared guanine derivative. The ligand and complexes were characterized by using infrared spectra, ultraviolet-visible spectra, 1 H-N.M.R., 13 C-N.M.R. spectra, and elemental analysis (C.H.N.S.): molar conductivity measurement, magnetic susceptibility, atomic absorption, and melting point. The results of these studies showed that general formulas for these complexes were given [MCl2(O.P.P.)2], M = (Mn +2 , Co +2 , Ni +2 , Cu +2 , Zn +2 , Cd +2 , and Pd +2 ). It was found that the geometric shape of all the prepared complexes was an octahedron. Keywords: Guanine, propionyl chloride, isothiocyanate, coordination complexes, organometallic compounds. 1. Introduction Bioinorganic chemistry is a field of chemistry that focuses on the study of the interactions between inorganic molecules and biological systems. It involves the study of metal ions and their coordination chemistry in biological systems, as well as the role of inorganic elements and compounds in biological processes [1,2]. Received: 6 March 2023 Accepted: 23 May 2023 Published: 20 April 2024 Synthesis and Spectral Study of New Guanine Derivative (N-((6-Oxo-6,9-Dihydro- 1H-Purin-2-yl)Carbamothioyl)Propionamide) and its Complexes with Some Metals Ion doi.org/10.30526/37.2.3313 https://creativecommons.org/licenses/by/4.0/ https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://jih.uobaghdad.edu.iq/index.php/j/index#1609-4042 https://jih.uobaghdad.edu.iq/index.php/j/index#2521-3407 https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com https://orcid.org/0000-0002-4820-0859 mailto:abdulaalany@googlemail.com https://orcid.org/0000-0003-3813-5982 mailto:bmsarhan@yahoo.com https://orcid.org/0000-0003-2802-0292 mailto:vdtmkclnmu@gmail.com IHJPAS. 37 (2) 2024 286 The preparation of metallic coordination complexes with biological molecules is an active area of research in bioinorganic chemistry because these complexes can have a variety of biological applications. For example, some of these complexes have been studied for their potential use as anticancer agents, antibacterials, antifungals, or catalysts for important biological reactions [3–10]. The preparation of these complexes often involves modifying the biological molecules to create ligands that can coordinate with metal ions and form stable complexes [3,10–14]. This can affect the use of synthetic organic chemistry techniques to develop modified versions of naturally occurring biological molecules or the development of entirely new ligands that can alter the properties of biological molecules [4,15–17]. The objective of this study is to synthesize and analyze the properties of a novel ligand (OPP) (N-((6-oxo-6,9-dihydro-1H-purin-2-yl)carbamothioyl)propionamide), and its complexes with some metal ions. 2. Materials and Methods 2.1 Chemicals All reagents, chemicals, metal chloride salts, and solvents were purchased from Merck, Fluorochem, Fluka, Sigma-Aldrich, J.T. Baker, BDH, Riedel-De Haen Merk, and Honeywell with high purity. 2.2 Synthesis of the ligand (OPP) A- About 30 mmol, 2.28 g of ammonium thiocyanate was dissolved in 20 mL of acetone with stirring, then 30 mmol, 2.77 mL of propionyl chloride was added to the solution and stirred for about 3 hours, then filter. The product was a yellow solution. B- About 30 mmol, 4.53 g of guanine was dissolved in 20 mL of acetone, then mixed with the former solution above, refluxed the mixture with a water bath for 6 hours, let dry, and then recrystallized with ethanol [18,19], as in Scheme 1. Scheme1. Preparation of ligand (OPP). The product was orange gummy, yield (63%), m.p (134°C), C% found (40.48) calc.(40.60), H% was found (3.47) calc.(3.79), N% was found (31.33) calc.(31.56), S% was found (12.39) calc.(12.04), and O% was found (12.39) calc.(12.02). IHJPAS. 37 (2) 2024 287 2.3 Synthesis of metal complexes A- About 2 mmol, 0.532 g of the guanine derivative was dissolved in 10 mL of ethanol. B- About 1 mmol of the metal salts (0.197 g of MnCl2.4H2O, 0.237 g of CoCl2.6H2O, 0.237 g of NiCl2.6H2O, 0.170 g of CuCl2.2H2O, 0.136g of ZnCl2, 0.201 g of CdCl2.H2O, and 0.177 g of PdCl2.H2O) were dissolved in the least amount of ethanol, then this solution was added to the solution obtained from the previous step and the mixture stirred for 4 hours to form a precipitate that is separated by filtration, washed with ethanol, and leave to dry [19,20]. Table 1 shows some physical properties of the prepared complexes. 3. Results and Discussion The solid complexes that were synthesized displayed solubility in certain typical solvents, including dimethyl formamide and dimethyl sulphoxide, and exhibited considerable thermal stability. When dissolved in DMSO, all complexes demonstrated non-electrolytic behavior, as evidenced by their molar conductivity. Table 1 shows the percentage of physical properties and metals in complexes and the molar conductivity of the ligand and its metallic complexes. Table 1. The physical properties of the ligand and its metallic complexes. Compound Color M.Wt (g/mol) M.p.(Dec.) °C M% Calculation (Found) Molar condu. Ohm -1 cm 2 mol -1 (OPP) Orange 266.28 134 -- (--) --- [MnCl2(OPP)2] Yellow 658.40 142 8.34 (8.58) 14 [CoCl2(OPP)2] Blue 662.39 164 9.80 (9.72) 12 [NiCl2(OPP)2] Green 662.15 168 8.86 (9.01) 18 [CuCl2(OPP)2] Blue 667.00 --- (182) 9.53 (9.77) 12 [ZnCl2(OPP)2] White 688.84 --- (168) 9.78 (9.72) 10 [CdCl2(OPP)2] White 715.87 --- (192) 15.70 (15.83) 8 [PdCl2(OPP)2] Brown 709.88 --- (188) 14.99 (15.08) 2 The FT-IR spectrum for free ligand OPP in Figure 1, detected a medium band at (3160 cm -1 ) for υ(NH), medium band at (1604 cm -1 ) for υ(C=O amidic) and another bands at (1226 cm -1 ) for υ(C=S) and a strong band at (1695 cm -1 ) for υ(C=O) of the guanine ring [22], Table 2 and Figure 1. Table 2. The FT-IR bands for guanine and free ligand OPP. Compound ν(N-H2+OH) ν(N-H+OH) ν(C=O) Amide ν(C=S) ν(C=O) in purin ring Guanine 3321(m) 3116(m) --- --- 1693(s) OPP ----- 3160(m) 1604(s) 1226(s) 1695(s) IHJPAS. 37 (2) 2024 288 Figure 1. The FT-IR spectrum of ligand (OPP). The 1 H-NMR spectrum of ligand (OPP) in DMSO-d6 in Figure 3 showed a doublet signal at δ(1.03) ppm for (3H, of CH3 methyl), a pentet signal at δ(2.145) ppm for two protons in (CH2, methylene), a single signal at δ(2.51) ppm for (DMSO), a single signal at δ(7.02) ppm for one proton of (N-H imidazole ring), a single signal at δ(7.28) ppm for one proton (C-H in imidazole ring), a single signal at δ(9.34) ppm for one proton of (NH, amine), a single signal at δ(9.64) ppm for one proton in (NH, amide). Also, a single signal at δ(11.048) ppm for one proton in (NH, guanidine) [22], Table 2. Figure 2. The 1 H-NMR spectrum of ligand (OPP). Table 3. The 1 HNMR signals for ligand (OPP). Symbol Δppm Signal No.of point Group a 1.03 Doublet 3H CH3, Methyl b 2.145 Pentlet 2H CH2, Methylene c 7.02 Singlet 1H N-H, imidazole ring d 7.28 Singlet 1H C-H, imidazole ring e 9.34 Singlet 1H N-H, amine f 9.64 Singlet 1H N-H, amide g 11.04 Singlet 1H N-H, guanidine IHJPAS. 37 (2) 2024 289 While the 13 C-NMR spectrum of ligand OPP in Figure 4, DMSO-d6 showed a single signal at δ(10.23) ppm for (CH3, methyl), a single signal at δ(30.02) ppm for (CH2 methylene), a single signal between δ(39.31-39.93) ppm for (DMSO), a single signal at δ(124) ppm for (C in imidazole ring), a single signal at δ(143) ppm for (CH of purine ring), a single signal at δ(150) ppm for (C-NH, in purine ring), a single signal at δ(159) ppm for (C=O, of purine ring), a single signal at δ(166) ppm, for (C-NH, in purine ring), a single signal at δ(176) ppm, for(C=O, amide), and a single signal at δ(184) ppm, for (C=S), Table 3. Figure 3. The 13 C-NMR spectrum of ligand (OPP). Table 4. The 13 CNMR signals for ligand (OPP). Symbol Δppm Group a 10.23 CH3,Methyl b 30.02 CH2,Methylene c 124 C- imidazole ring d 143 CH in purine ring e 150 C-NH in purine ring f 159 C=O in purine ring g 166 C-NH in purine ring h 176 C=O, amid i 184 C=S According to Figure 5, the UV-visible spectra of the ligand OPP (0.01M in DMSO) in Table 4 displayed a band at (36101) cm -1 , which was attributed to the π→π* transition, while a band at (27777) cm -1 was observed due to the n→ π* transitions [23]. Figure 5. The UV-visible spectrum of ligand (OPP). IHJPAS. 37 (2) 2024 290 -[MnCl2(OPP)2] d 5 , displayed distinct spectral bands at (35087), (28735), and (10183) cm -1 were due to (L.F.) transitions, (C.T.), and ( 6 A1g → 4 T1(G)) transitions, respectively [19,23]. -[CoCl2(OPP)2] d 7 in Figure 6, exhibited clear spectral bands at (34482), (28735), (34482), and (14836) cm -1 , which were associated with (L.F.), and (C.T.) that mix with ( 4 T1(f) → 4 T1(p)) transitions, ( 4 T1g(f) → 4 A2g) transitions, and ( 4 T1g(f) → 4 T2g) transitions, respectively [24,25]. Figure 6. The UV-visible spectrum of [CoCl2(OPP)2]. -[NiCl2(OPP)2] d 8 , the complex exhibited distinct spectral bands at (34013, 28735, 15197) and (11299) cm -1 , which were for ligand field (LF), charge transfer (CT) that mix with ( 3 A1g 3 T1g(p)), ( 3 A2g 3 T1g), and ( 3 A2g 3 T2g) transitions, respectively [24,25]. -[PdCl2(OPP)2] d 8 in Figure 10, the complex exhibited distinct spectral bands at (34013, 28735,15197), and 11299) cm -1 , which were assigned for (L.F.), (C.T.) that mix with the ( 3 A1g 3 T1g(p)), ( 3 A2 3 T1g), and ( 3 A2g 3 T2g) transitions, respectively [24,25]. -[CuCl2(OPP)2] d 9 in Figure 7, displayed distinct spectral bands at (35087 and 10593) cm -1 which were attributed to (L.F.) and ( 2 Eg 2 T2g) transitions, respectively [23]. Figure 7. The UV-visible spectrum of [CuCl2(OPP)2]. The complexes of [ZnCl2(OPP)2] and [CdCl2(OPP)2] in Figures 12 and 13, respectively, showed ligand field effects in the range (34129-34013) cm -1 and charge transfer of (M L), in the range (29735-28735) cm -1 [24]. IHJPAS. 37 (2) 2024 291 Table 5. The UV-visible spectral data of the ligand OPP complexes and its complexes (10 -3 M in DMSO). The FT-IR spectra of seven prepared complexes were recorded within the range (4000-200) cm -1 as (CsI) discs and showed significant differences in the bands associated with the stretching vibration at 1226 cm -1 in the ligand spectrum, which is assigned to the ν(C=S) in the range of (1182-1159) cm -1 . These bands were shifted lower by (44-23) cm -1 in the spectra of the complexes, indicating the involvement of the sulfur atom in the thione group in coordination [26], Table 5. The band caused by ѵ(C=O amide) in the range of (1595-1525) cm -1 was shifted to lower frequencies by (79-9) cm -1 , suggesting the possibility of coordination of the ligand through the O-atom at the carbonyl group the metal complexes [27,28] as in Figures 8 and 9. The coordination of M-O and M-S was evidenced by the appearance of stretching vibrations at around (487-455) cm -1 , ( 379-308) cm -1 , and (293-262) cm -1 , respectively, which correspond to υ(M-O), υ(M-S), and υ(M-Cl), [29]. Table 6 describes the critical bands and their assignments for the free ligand (OPP) and its complexes that were prepared. Compounds (nm) υ - (cm -1 ) ABC εmax molar- 1 cm -1 Transitions (OPP) 277 360 36101 27777 2.213 0.383 2213 383 * n* [MnCl2(OPP)2] 285 348 982 35087 28735 10183 2.366 0.837 0.025 2366 837 25 (L.F.) (C.T) 6 A1g → 4 T1(G) [CoCl2(OPP)2] 290 348 678 870 34482 28735 14836 34482 2.399 1.050 0.110 0.035 2399 1050 110 35 (L.F.) (C.T.)mix 4 T1(f) → 4 T1(p) 4 T1g(f) 4 A2g 4 T1g(f) 4 T2g [NiCl2(OPP)2] 294 348 658 885 34013 28735 15197 11299 2.416 1.169 0.036 0.035 2416 1169 36 35 (L.F.) (C.T.)mix 3 A1g → 3 T1g(p) 3 A2g → 3 T1g 3 A2g → 3 T2g [CuCl2(OPP)2] 285 944 35087 10593 2.369 0.078 2369 78 (L.F.) 2 Eg → 2 T2g [ZnCl2(OPP)2] 294 348 34013 28735 2.442 1.266 2442 1266 (L.F.) (C.T.) [CdCl2(OPP)2] 293 348 34129 29735 2.383 1.050 2383 1050 (L.F.) (C.T.) [PdCl2(OPP)2] 273 352 982 36630 28409 10183 1.628 0.552 0.069 1628 552 69 (L.F.) (C.T.)mix 3 A2g → 3 T1g(p) 3 A2g → 3 T2g IHJPAS. 37 (2) 2024 292 Figure 8. The FT-IR spectrum of [CdCl2(OPP)2] complexes. Figure 9. The FT-IR spectrum of [ZnCl2(OPP)2] complexes. Figure 10. The FT-IR spectrum of [ZnCl2(OPP)2] complexes. IHJPAS. 37 (2) 2024 293 Table 6. The important bands and assignment for (OPP) and its metal complexes. Compound ν(N-H) ν(C=O) Amide ν(C=S) ν(M-O) ν(M-S) ν(M-Cl) Ligand (OPP) 3160(m) 1604(m) 1226(m) ----- ----- ----- [MnCl2(OPP)2] 3163(m) 1593(s) 1159(s) 480(w) 379(w) 293(w) [CoCl2(OPP)2] 3170(m) 1527(s) 1180(s) 462(w) 329(w) 268(w) [NiCl2(OPP)2] 3170(m) 1595(s) 1182(s) 480(w) 312(w) 264(w) [CuCl2(OPP)2] 3178(m) 1529(m) 1161(m) 487(w) 310(w) 270(w) [ZnCl2(OPP)2] 3180(m) 1525(m) 1163(m) 455(w) 308(w) 271(w) [CdCl2(OPP)2] 3150(m) 1544(s) 1159(s) 455(w) 351(w) 262(w) [PdCl2(OPP)2] 3166(m) 1535(m) 1161 (s) 462(m) 351(w) 258(w) The magnetic susceptibilities of these complexes were in good agreement with the values expected for high spin [29,30]; the magnetic susceptibilities of these complexes are listed in Table 7. Table 7. Magnetic susceptibilities data of (OPP) complexes. Complexes Gram susce. Xg x 10 -6 Molar susce. XM x 10 -6 Atomic susce. XA x 10 -6 μ eff (B.M) No. of unpaired electrons Proposed structure [MnCl2(OPP)2] 22.46 1478.4394 14787.4394 5.96 5 Oh [CoCl2(OPP)2] 14.35 9506.7315 9631.9115 4.79 3 Oh [NiCl2(OPP)2] 5.41 3582.8807 3708.0607 2.97 2 Oh [CuCl2(OPP)2] 1.66 1107.22 1232.4 1.71 1 Oh [ZnCl2(OPP)2] 0 0 0 0 0 Oh [CdCl2(OPP)2] 0 0 0 0 0 Oh D = 125.18˟10 -6 Based on molar conductivity, magnetic moment, and spectroscopic studies (including FT-IR, UV-Vis, 1 H- 13 C NMR, and atomic absorption), this study determines that the ligand OPP acts as a bidentate ligand when coordinating with Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pd(II) ions. Specifically, the oxygen atom of the amido group (C=O) and the sulfur atom of the thioamide group (C=S) are involved in coordination with the metal ion. This suggests an octahedral geometry around the metal ion for all of the prepared complexes, Scheme 2. Additionally, FT-IR studies for the OPP ligand show that it is coordinates with the mentioned functional groups. Scheme 2. Octahedral geometry of complexes. IHJPAS. 37 (2) 2024 294 4. Conclusion This study utilizes a variety of analytical techniques to determine that the OPP ligand acts as a bidentate ligand when coordinating with Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pd(II) ions. The amido group's oxygen atom (C=O) and the thioamide group's sulfur atom (C=S) coordinated with the metal ion, resulting in an octahedral geometry around the metal ion for all prepared complexes, as shown in Scheme 2. Furthermore, the OPP ligand showed that coordination occurred through the mentioned functional groups and the formation of hexagonal rings between the ligands and metal ions, which increased the stability of these complexes. In summary, this study provides comprehensive insights into the coordination behavior of the OPP ligand with various metal ions. It offers a detailed understanding of the structures of the prepared complexes using multiple analytical techniques. Acknowledgment The authors thank all those who contributed to the completion of this research project. First and foremost, they extend their heartfelt appreciation to Basima Muhsen Sarhan and Vishwa Deepak Tripathi for their invaluable guidance, encouragement, and expertise throughout this research. Their insightful feedback and unwavering support were instrumental in shaping the direction of this work. They also thank their colleagues and collaborators for their assistance and valuable discussions, which significantly contributed to the development and refinement of their ideas. Lastly, the authors would like to acknowledge the anonymous reviewers, whose constructive feedback and suggestions helped strengthen the manuscript. Conflict of Interest The authors declare that they have no conflicts of interest. Funding There is no financial support. 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