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Article

A New Bromo-Mn(II) Complex with 1,3,5-Triazine Derivative: Synthesis, Crystal Structure, DFT and Biological Studies

by
Sara M. Khattab
1,*,
Mezna Saleh Altowyan
2,
Ayman El-Faham
1,3,
Assem Barakat
4,*,
Matti Haukka
5,
Morsy A. M. Abu-Youssef
1 and
Saied M. Soliman
1
1
Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria 21321, Egypt
2
Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia
3
Department of Clinical Sciences, College of Medicine, Dar Al Uloom University, P.O. Box 45142, Riyadh 11512, Saudi Arabia
4
Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
5
Department of Chemistry, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland
*
Authors to whom correspondence should be addressed.
Inorganics 2024, 12(11), 284; https://doi.org/10.3390/inorganics12110284
Submission received: 3 October 2024 / Revised: 28 October 2024 / Accepted: 29 October 2024 / Published: 31 October 2024
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Abstract

:
The crystal structure and topology analyses of a new bromo-Mn(II) complex with 2,4-bis(3,5dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (MBPT) were reported. Its structure was confirmed using single-crystal X-ray diffraction to create the formula [Mn(MBPT)Br(H2O)2]ClO4. Its crystal system was monoclinic and its space group was p21. The Mn(II) was coordinated with MBPT as a NNN-pincer ligand, with one bromide ion in the equatorial plane. The two axial terminals were occupied by two trans water molecules. H…H, N…H, Br…H, C…H and O…H were the predominant intermolecular contacts, while Br…H, O…H and C…O were the significant contacts based on Hirshfeld analysis. Moreover, anion–ᴨ interaction was found between C(s-triazine) and O(perchlorate). This complex had better antioxidant activity than the free ligand (MBPT). In addition, the cytotoxicity of the [Mn(MBPT)Br(H2O)2]ClO4 complex showed better results against HepG-2 and MCF-7 cells, recording IC50 values of 31.11 ± 2.04 and 50.05 ± 2.16 µM, respectively, compared to the free ligand (IC50 = 671.44 ± 21.41 and 1113.55 ± 29.77 µM). In comparison to cis-platin as a reference drug, the IC50 values were 63 and 80 μM, respectively, which indicated the promising anticancer activity of the studied compound against both cell lines. In terms of the safety of normal cells, the Mn(II) complex recorded a high IC50 value of 359.10 ± 8.72 µM against the WI-38 non-cancerous cell line. The complex showed better activity towards Staphylococcus aureus, Bacillus subtilis, and Proteus vulgaris relative to the free MBPT, but had low to moderate activity compared to Gentamycin as an antibacterial positive control.

Graphical Abstract

1. Introduction

Manganese is regarded as one of the most important micro-nutrients in the human body [1]. It is involved in many vital processes inside biological systems such as the synthesis and activation of several enzymes (e.g., redox or hydrolytic transformations), the metabolism of carbohydrates and lipids, and assistance in the production of proteins and some vitamins (in particular, C and B) [2,3,4]. For the past few decades, complexes of manganese gained special attention due to their exceptional role in biomedical applications and the ability of their ions to have different oxidation states [5,6]. For instance, various Mn(II) complexes can be used as contrast-enhanced MRI agents [7,8,9], and in manganese superoxide dismutase (MnSOD) mimetics, which are responsible for the reduction in reactive oxygen species (ROS) that cause oxidative stress inside mitochondria [10,11,12,13,14]. The overall physiological roles of manganese help in improving human immunity [4]. The increased selectivity of the manganese element in forming high-stable complexes with certain organic ligands introduces extra privilege for it among the other available first row transition metal ions (e.g., Zn, Fe, and Cu) [1]. The ligands that are responsible for manganese chelation are known as sequestering agents, which prevent overload Mn(II) accumulation [15]. Moreover, manganese complexes are attracting current focus due to their low in vivo toxicity, and their remarkable antimicrobial and anticancer activities, which make them good candidates for different infection diseases and cancer treatments instead of platinum-based chemotherapeutic drugs such as cis-platin [16,17].
s-Triazine and its derivatives have very interesting and promising potential due to their presence in many naturally occurring substances and their affordability. Also, they are common in various commercially available drugs that are used as anticancer, antimicrobial, antiviral and anti-inflammatory agents [18,19,20]. In recent years, several studies were performed to introduce active heterocyclic add-ons to the s-triazine nucleus to obtain more potent compounds [19]. In addition, pyrazoles were investigated as important heterocyclic analogs due to possessing remarkable bioactivities that are like that of s-triazines [21,22,23,24]. For example, novel derivatives of mono- and bis(dimethylpyrazolyl)-s-triazine were synthesized and tested on several cancerous cell lines (e.g., breast cancer, colon cancer, and liver cancer cell lines) that showed very promising results [21]. 2,4-Bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (MBPT, Figure 1) was an interesting N,N,N-pincer ligand. This interesting chelator is capable of coordinating different metal ions, leading to many coordination compounds with interesting biological activities [25,26,27,28].
The previously reported Ni(II), Zn(II) and Co(II) complexes with this ligand were found to have interesting molecular and supramolecular structures in addition to their diverse biological activity as antimicrobial and anticancer agents where the nature of the metal ion, coordinating ligand and anionic groups, affected their biological potentials [25,26,27,28]. In continuation of our previous studies, herein, we synthesized a new bromo Mn(II)–MBPT complex, exploring its antimicrobial, antioxidant and anticancer properties. In this regard, its cytotoxicity was examined against three cancerous cells (A-549, MCF-7 and HepG-2). In addition, its crystal structure was reported for the first time in combination with its Hirshfeld analysis.

2. Results and Discussion

2.1. Synthesis and Characterization

The self-assembly of manganese perchlorate, MBPT and KBr in an ethanol–water mixture as solvent afforded the bromo Mn(II) pincer complex a good yield. The weak coordinating ability of the perchlorate anion enabled the incorporation of the bromide ion into the coordination sphere of the complex (Scheme 1). Its molecular formula was assigned to be [Mn(MBPT)Br(H2O)2]ClO4 based on the X-ray diffraction of a single crystal. The FTIR spectra provided the essential evidence on the complexation between Mn(II) and MBPT. Two characteristic bands were observed at 1541 and 1614 cm−1 for the [Mn(MBPT)Br(H2O)2]ClO4 complex, which were attributed to the υ(C=N) stretching vibration mode of the pyrazole rings and the triazine moiety, respectively [29,30]. The respective values for MBPT were 1561 and 1598 cm−1 [25]. The sharp peak at 629 cm−1 could be related to δ(ClO) asymmetric bending (υ4), while the broad triple split band at 1037, 1083 and 1134 cm−1 could be related to the υ(ClO) asymmetric stretching (υ3) bands (Figure S1) [31,32,33].

2.2. Crystal Structure Description

The structural aspects of [Mn(MBPT)Br(H2O)2]ClO4 were investigated via single-crystal X-ray diffraction measurement. The new complex had the monomeric formula [Mn(MBPT)Br(H2O)2]ClO4 as an asymmetric unit (Figure 2). The complex [Mn(MBPT)Br(H2O)2]ClO4 was crystallized in the monoclinic crystal system, the P21 space group and Z = 4.
The cationic coordination sphere of this complex comprised hexa-coordinated Mn(II) with one MBPT as a N,N,N-pincer ligand, one bromide ion and two H2O molecules trans to one another. The outer sphere had one perchlorate ion (Figure 2). An analysis of the bond distances around the Mn(II) central atom showed that the two axial Mn1-O1 (2.196(4) Å) and Mn1-O2 (2.155(5) Å) bonds were the shortest, while the Mn1-Br1 was the longest bond (2.6018(10) Å). The manganese to nitrogen distances were variable, where Mn1-N3 (2.221(5) Å), which belongs to s-triazine ring, was significantly shorter than the Mn1-N1 (2.304(5) Å) and the Mn1-N7 (2.296(5) Å) of the two pyrazoles rings [25]. The two bite angles N3-Mn1-N1and N3-Mn1-N7 of the tridentate ligand were 69.39(18) and 69.23(19)°, while the angle between the two Mn-N bonds of the trans pyrazole moieties (N7-Mn1-N1) was 137.64(19)°. The angles between the two axial water molecules and the bromide ion were determined to be 85.57(12) and 88.90(14)° for O1-Mn1-Br1 and O2-Mn1-Br1, respectively, while the trans bond angle O2-Mn1-O1 was 171.7(2)° (Table 1). Hence, the coordination geometry around Mn(II) was distorted octahedra.
Intermolecular H-bonds and anion–π stacking were the driving forces behind the packing of the [Mn(MBPT)Br(H2O)2]ClO4 complex in the 3D structure where these supramolecular interactions were clearly shown in Figure 3. Hydrogen bonding interactions including the O-H…O and O-H…Br interactions are depicted in Table 2. The hydrogen acceptor distances for the O1-H1A…O5 and O2-H2A…O5 hydrogen bonds were 2.10 and 2.48(17) Å, respectively, while the related donor-to-acceptor distances were 2.876(10) and 3.047(12) Å, respectively. The O2-H2B…Br1 and O1-H1B…Br1 hydrogen bonds had oxygen-to-Br distances of 3.314(5) and 3.338(4) Å, respectively. On a worthy note, the extensive intermolecular hydrogen bonding system (O-H…O) generated the differences in the Cl-O bond lengths (1.258(9)–1.398(8) Å; Table 1) which explains the complicated character of the band assigned to the υ3 vibration mode of the perchlorate group in the IR spectrum [34].
In addition, anion–π interactions were detected in the crystal structure of the [Mn(MBPT)Br(H2O)2]ClO4 complex (Figure 4). Three significant anion–π contacts were recognized between the carbon atoms of the s-triazine core and the oxygen atoms of the perchlorate anion. The C8…O4a (3.02(2) Å; Symm. code: x,y,−1 + z), C8…O6 (3.20(1) Å) and C7…O6 (3.18(2) Å) short contacts confirmed the presence of anion–π stacking interaction.

2.3. Hirshfeld Surface Analysis

A Hirshfeld surface analysis was used to further investigate the most significant intermolecular interactions that control the molecular packing of [Mn(MBPT)Br(H2O)2]ClO4. The leading contacts were indicated as red circles with shorter distances, while the blue regions had longer distances and the white regions had equal distances compared to the sum of the van der Waals radii of the interacting atoms. The studied surface was visualized by dnorm, shape index and curvedness functions (Figure 5). The dnorm map was in a color range from 0.1 to 1.0; the strong close contacts are given in Table 3.
The predominant interactions in the crystal structure were the H…H, O…H, Br…H, C…H and N…H, which participated by 42.8, 23.4, 10.6, 9.0 and 7.3%, respectively (Figure 6). The anion–π interaction generally existed between C(s-triazine) and O(perchlorate), which contributed to 2.4% of the total interactions. Moreover, C8…O4 was the shortest (3.02(2) Å) while the other two anion–π interactions of C7…O6 and C8…O6 were almost equal (3.18 and 3.20 Å, respectively).
The Br…H, O…H and C…O contacts appeared in the dnorm map as red regions, indicating their importance for molecular packing. The spikes in the fingerprint plots emphasized the most important contacts while the area of the fingerprint plot represented the contacts’ contribution (Figure 7). As clearly seen from Table 3, the H2B…Br1, H1A…O5 and C8…O4 contacts had the shortest distances of 2.360, 1.980 and 3.022 Å, respectively. It is worthy to note that the two spikes of the O…H/H…O contacts were not symmetric, indicating that the surface was more likely to be a hydrogen bond donor for this type of intermolecular interaction. On the other hand, the two spikes of the Br…H/H…Br contacts were looking symmetric, indicating that the surface was acting as both a hydrogen bond donor and an acceptor with respect to the Br…H interactions.

2.4. Metal Affinity Study

A comparative discussion illustrating the affinities of some divalent metal ions [26,27,28,35] towards the MBPT ligand was introduced. The interaction energies were calculated for the cationic complex units [M-MBPT]2+, which revealed that Mn(II) in the [Mn(MBPT)Br(H2O)2]ClO4 complex had the lowest affinity towards the MBPT ligand. The main factors that affected the affinity of MBPT towards the M(II) ion were: (1) the metal ion charge, (2) the coordinating anionic or neutral ligand groups and (3) the metal ion size. Since all the studied systems had divalent metal ions, the two last parameters were the most effective in determining the metal affinity of MBPT. It is obvious that the largest M(II)-MBPT affinity was detected for the M(II) complexes that had no coordinating anion and a small size metal ion (Ni(II)), as found in complexes 7 and 8 (Table 4). The replacement of one aqua molecule via chloride as found in complex 6 led to the lowering of the metal affinity to 345.3815 kcal/mol. For the related Co(II) complexes (4 and 5), the Co(II)-MBPT affinities were less compared to 8 and 7, respectively, which could be attributed to the difference in the metal ion size.

2.5. Antioxidant Activity

1,1-Diphenyl-2-picrylhydrazyl (DPPH) is a standard stable organic radical, which is used in the quantitative assay of reactive oxygen species (ROS). Free radical scavenging is helpful to minimize the oxidative damage caused by ROS to the human body [36]. The antioxidant activities of [Mn(MBPT)Br(H2O)2]ClO4 and the ligand together with ascorbic acid were determined on the basis of the free radical scavenging ability of DPPH. The inhibition percents indicated that the Mn(II) complex was stronger than the ligand as a free radical scavenger and antioxidant, but weaker when compared to the ascorbic acid as a standard. The values of the calculated IC50 of the Mn(II) complex and vitamin C were 824.97 ± 41.71 and 57.97 ± 4.37 µM, respectively, while the ligand showed almost no antioxidant activity under the same experimental conditions (Figure S2). The antioxidant activity of the previously studied structurally related metal(II) complexes were compared to that for the [Mn(MBPT)Br(H2O)2]ClO4 complex. The [Zn(MBPT)(NCS)2] and [Zn(MBPT)(Br)2] complexes had IC50 values of 156.996 ± 8.5 and 675.286 ± 38.59 µM, respectively [27], which were generally better antioxidants than the [Mn(MBPT)Br(H2O)2]ClO4 complex.

2.6. Antimicrobial Assay

Antibacterial screening of the [Mn(MBPT)Br(H2O)2]ClO4 complex was examined on two Gram-positive bacteria Staphylococcus aureus (RCMB010010) and Bacillus subtilis RCMB 015 (1) NRRL B-543, and two Gram-negative bacteria, namely, Escherichia coli ATCC 25922 and Proteus vulgaris RCMB 004 (1) ATCC 13315. The agar–well diffusion technique was used for the antimicrobial assay [37], where all the samples were tested at 10 mg/mL concentration and compared with the Gentamycin antibiotic as a positive control. The results showed the enhanced activity of the Mn(II) complex against all the tested strains (except E. coli) compared to the free ligand. The latter showed no activity against the variety of pathogens [27], which corroborates that the enhanced activity of the complex could be related to its lipophilic character [38]. The studied Mn(II) complex was active against S. aureus (14 mm), B. subtilis (19 mm), and P. vulgaris (16 mm). For Gentamycin, the respective values were 24, 26 and 25 mm. Hence, the antibacterial activity of the Mn(II) could be considered good with respect to the standard antibiotic. Further, antifungal scanning showed no activity against the A. fumigatus and C. albicans fungal species (Table S1).

2.7. Safety Assay

An in vitro viability assessment was made to figure out the safety pattern of the [Mn(MBPT)Br(H2O)2]ClO4 complex and the MBPT ligand, where variable concentrations were prepared to test the safety profile of both the samples against WI-38 (the human lung fibroblast non-cancerous cell line, provided by ATCC, Rockville, MD). Using an MTT assay, IC50 values were determined to be 359.10 ± 8.72 and 1320.22 ± 31.64 µM for [Mn(MBPT)Br(H2O)2]ClO4 and MBPT, respectively (Figure S3). Hence, the complex showed higher cytotoxicity than the free ligand. Regardless, the IC50 value of the Mn(II) complex was considered high and indicated its relatively higher in vitro safety pattern towards the non-cancerous cell line.

2.8. Cytotoxicity Assay

The in vitro anticancer activities of [Mn(MBPT)Br(H2O)2]ClO4 and the free ligand were studied against the A-549 (lung carcinoma), MCF-7 (breast cancer), HeLa(Cervical cancer), and HepG-2 (Human liver cancer) cell lines (ATCC, Rockville, MD) at different concentrations by using an MTT assay. The cytotoxicity results shown in Figure 8 indicated that the Mn(II) complex markedly inhibited all the selected cancerous cell lines to different extents.
The maximum percentages of inhibition on A-549 after treatment with the Mn(II) complex and the ligand were 75.29 and 71.61%, respectively, and the IC50 values were 557.75 ± 20.15 and 1245.41 ± 45.57µM, respectively. The inhibition percentages of the complex and the ligand on MCF-7 were 94.17 and 80.28%, respectively, with IC50 values of 50.05 ± 2.16 and 1113.59 ± 29.77 µM, respectively. Furthermore, the highest inhibition percentages of the Mn(II) complex and the ligand on HeLa were 89.64 and 76.85%, respectively, with IC50 values of 216.35 ± 5.34 and 1198.58 ± 31.87µM, respectively. The results showed that the most sensitive cell line to the treatment was HepG-2 with the inhibition percentages of the complex and the ligand equal to 96.83 and 91.06%, respectively. The IC50 values were 31.11 ± 2.04 and 671.47 ± 21.41µM for the complex and the ligand, respectively (Table S2). Obviously, the cytotoxic effect was enhanced by the presence of the metal ion, the polarity of which decreased upon chelation, and the delocalization of the π-electrons increased over the whole coordination sphere, promoting the lipophilicity of the Mn(II) complex. Moreover, as the lipophilicity increased the permeation of the metal chelate to the cell membrane increased through its lipid layer [39].
For the MCF-7 and HepG-2 cell lines, which exhibited intrinsic resistance to cis-platin, the IC50 values of the reference drug were of 80 [40] and 63 μM [41], respectively, while the [Mn(MBPT)Br(H2O)2]ClO4 complex recorded a better response with an IC50 value equal to 50.05 ± 2.16 μM. In addition, the anticancer activity of the Mn(II) complex was compared to the Co(II) complexes’ activities against the MCF-7 cell line of the same ligand (MBPT).The IC50 values of complexes 2–5 were 439.27 ± 19.76, 438.79 ± 19.17, 674.40 ± 30.85, and 431.23 ± 20.28 μM, respectively [28], where the Mn(II) complex had the highest efficacy among them (Figure 9).

3. Materials and Methods

3.1. Materials and Physical Characterization

All the details about the materials and physical characterization are described in Supplementary Data.

3.2. Synthesis

The method described by our research team was used to prepare the MBPT pincer ligand [25].

Synthesis of the [Mn(MBPT)(H2O)2Br]ClO4 Complex

A solution of Mn(ClO4)2 (25.4 mg, 0.1 mmol) in 10 mL EtOH was mixed with 10 mL hot ethanolic solution of MBPT (29.9 mg, 0.1 mmol). Then, 1 mL of KBr aqueous solution (11.9 mg, 0.1 mmol) was added to the resulting mixture. A clear mixture was obtained which was able to slowly evaporate at R.T. Colorless crystals were formed after three days and subsequently collected through filtration. These crystals were found to be appropriate for single crystal X–ray diffraction analysis.
The yield was as follows: 87%; Anal. Calc. C14H21N7O7MnClBr: C, 29.52; H, 3.72; N, 17.21 and Mn, 9.64%. The following were found: C, 29.41; H, 3.77; N, 17.13 and Mn, 9.70%. The values for [Mn(MBPT)(H2O)2Br]ClO4 FTIR cm−1 were as follows: 3418, 1614, 1514, 1488, 1360, 1223, 1084, 1037, 978, 756 and 629 (Figure S1).

3.3. Crystal Structure Determination

The procedures mentioned in Method S1 (Supplementary Data) describe the crystal structure determination of the studied complex [42,43,44,45,46]. The details of the crystal data and structural refinements are given in Table 5. In addition, Crystal Explorer 17.5 software [47] was applied to carry out the Hirshfeld calculations [48] for molecular packing analysis.

3.4. Biological Studies

Using the protocol outlined in Method S2 (Supplementary Materials), the antimicrobial activities of the studied complex and its free ligand against various microbes were examined [49]. Furthermore, by applying Methods S3 and S4, the safety assay and anticancer activities were evaluated. Finally, the antioxidant activities were examined via Method S5 [50,51,52,53].

3.5. Computational Studies

The interaction energies of the [Mn(MBPT)Br(H2O)2]+ complex were calculated based on the X-ray structure of the [Mn(MBPT)Br(H2O)2]ClO4 using Gaussian 09 software [54]. The ωB97XD [55] method was used for this task. The 6-311G(d,p) basis sets were used for all the atoms except Mn (LANL2DZ).

4. Conclusions

The synthesis of [Mn(MBPT)Br(H2O)2]ClO4 was afforded by mixing a bis-pyrazol-methoxy-s-triazine pincer ligand (MBPT) and Mn(ClO4)2/KBr in water–ethanol solution. The reaction yielded a hexa-coordinated Mn(II) complex which comprised a tridentate N-chelator ligand (MBPT), two water molecules and one bromide ion, as revealed by single-crystal X-ray structure analysis. A Hirshfeld analysis showed that H…H (42.8%), O…H (23.4%), and Br…H (10.6%) were the predominant interactions in the crystal structure. Also, it revealed the presence of anion–π interactions between C(s-triazine) and O(perchlorate) with 2.4% of the whole interactions. The M(II)-MBPT affinities were explained in terms of the metal ion size and the nature of the other coordinating ligand groups. The [Mn(MBPT)Br(H2O)2]ClO4 complex had improved antioxidant, antibacterial and anticancer activities compared to the free ligand. The anticancer results showed high efficacy for the Mn(II) complex against HepG-2 and MCF-7 cell lines. Also, the Mn(II) complex had good activity against S. aureus and B. subtilis, and P. vulgaris.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/inorganics12110284/s1, Experimental details; Figure S1. FTIR spectra of the ligand MBPT (A) and [Mn(MBPT)(H2O)2Br]ClO4 complex (B); Figure S2. DPPH radical scavenging activity of Mn(II) complex, free ligand (MBPT) and ascorbic acid; Figure S3. Safety assay of [Mn(MBPT)Br(H2O)2]ClO4 and MBPT on the non-cancerous WI-38 cell line; Table S1. Zone of Inhibition (mm) for the [Mn(MBPT)Br(H2O)2]ClO4; Table S2. IC50 values (µM) of the studied systems; Method S1. Crystal structure determination; Method S2. Evaluation of antimicrobial activity; Method S3. Safety assay protocol; Method S4. Evaluation of cytotoxicity activity; Method S5. Evaluation of DPPH Radical Scavenging Activity.

Author Contributions

S.M.K.: methodology, investigation, data curation, formal analysis, validation, writing—original draft and writing—review and editing. M.S.A.: resources, software, funding, validation and data curation. A.E.-F.: conceptualization, supervision, investigation, formal analysis, resources, writing—original draft and writing—review and editing. A.B.: resources, software, validation, data curation, writing—original draft, reviewing and editing. M.H.: software, validation, data curation, writing—original draft, reviewing and editing. M.A.M.A.-Y.: conceptualization, supervision, supervision, investigation, software, formal analysis, methodology, validation, data curation, writing—original draft and writing—review and editing. S.M.S.: conceptualization, supervision, investigation, software, formal analysis, methodology, validation, data curation, writing—original draft and writing—review and editing. All authors have read and agreed to the published version of the manuscript.

Funding

Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2024R86), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.

Data Availability Statement

The original contributions presented in the study are included in the article and Supplementary Materials, further inquiries can be directed to the corresponding authors.

Acknowledgments

Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2024R86), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.

Conflicts of Interest

The authors declare no conflicts of interest.

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Inorganics 12 00284 g001
Figure 1. Structure of MBPT.
Figure 1. Structure of MBPT.
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Inorganics 12 00284 sch001
Scheme 1. Synthesis of [Mn(MBPT)Br(H2O)2]ClO4.
Scheme 1. Synthesis of [Mn(MBPT)Br(H2O)2]ClO4.
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Inorganics 12 00284 g002
Figure 2. The asymmetric unit structure and atomic numbering of the [Mn(MBPT)Br(H2O)2]ClO4 complex. Thermal ellipsoids were drawn at the 30% probability level.
Figure 2. The asymmetric unit structure and atomic numbering of the [Mn(MBPT)Br(H2O)2]ClO4 complex. Thermal ellipsoids were drawn at the 30% probability level.
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Inorganics 12 00284 g003
Figure 3. The significant H-bond contacts (A), and the H-bond packing along the bc plane (B).
Figure 3. The significant H-bond contacts (A), and the H-bond packing along the bc plane (B).
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Figure 4. Anion–π interactions in [Mn(MBPT)Br(H2O)2]ClO4.
Figure 4. Anion–π interactions in [Mn(MBPT)Br(H2O)2]ClO4.
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Inorganics 12 00284 g005
Figure 5. Hirshfeld surfaces illustrated with dnorm (A), shape index (B), and curvedness (C) maps in two different views.
Figure 5. Hirshfeld surfaces illustrated with dnorm (A), shape index (B), and curvedness (C) maps in two different views.
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Figure 6. The contributions of intermolecular interactions for the [Mn(MBPT)Br(H2O)2]ClO4 complex.
Figure 6. The contributions of intermolecular interactions for the [Mn(MBPT)Br(H2O)2]ClO4 complex.
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Inorganics 12 00284 g007
Figure 7. The dnorm maps of the close contacts and their corresponding 2D fingerprints.
Figure 7. The dnorm maps of the close contacts and their corresponding 2D fingerprints.
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Inorganics 12 00284 g008
Figure 8. Anticancer activities of the [Mn(MBPT)Br(H2O)2]ClO4 complex and the free ligand (MBPT) on the A-549 (a), MCF-7 (b), HeLa (c), and HepG-2 cell lines (d).
Figure 8. Anticancer activities of the [Mn(MBPT)Br(H2O)2]ClO4 complex and the free ligand (MBPT) on the A-549 (a), MCF-7 (b), HeLa (c), and HepG-2 cell lines (d).
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Inorganics 12 00284 g009
Figure 9. Anticancer activity expressed by IC50 values (μM) of different metal complexes against MCF-7 cell line.
Figure 9. Anticancer activity expressed by IC50 values (μM) of different metal complexes against MCF-7 cell line.
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Table 1. Bond distances and angles (Å, °) of the coordination sphere in [Mn(MBPT)Br(H2O)2]ClO4.
Table 1. Bond distances and angles (Å, °) of the coordination sphere in [Mn(MBPT)Br(H2O)2]ClO4.
Bond Distances
Mn1-O12.196(4)Mn1-N72.296(5)
Mn1-O22.155(5)Cl1-O51.398(8)
Mn1-Br12.6018(10)Cl1-O41.258(9)
Mn1-N12.304(5)Cl1-O61.343(10)
Mn1-N32.221(5)Cl-O71.389(13)
Bond Angles
O1-Mn1-Br185.57(12)O2-Mn1-N3101.70(19)
O1-Mn1-N187.42(19)O2-Mn1-N790.8(2)
O1-Mn1-N384.06(17)N3-Mn1-Br1169.27(13)
O1-Mn1-N796.95(18)N3-Mn1-N169.39(18)
N1-Mn1-Br1112.90(13)N3-Mn1-N769.23(19)
O2-Mn1-O1171.7(2)N7-Mn1-Br1109.45(14)
O2-Mn1-Br188.90(14)N7-Mn1-N1137.64(19)
O2-Mn1-N189.0(2)
Table 2. H-bond geometric parameters of [Mn(MBPT)Br(H2O)2]ClO4.
Table 2. H-bond geometric parameters of [Mn(MBPT)Br(H2O)2]ClO4.
D-H…AD-H(Å)H…A(Å)D…A(Å)D-H…A(°)Symm. Code
O1-H1A…O50.852.102.876(10)152.3
O1-H1B…Br10.852.583.338(4)148.4+x, 1/2 − y, 1/2 + z
O2-H2A…O50.890(10)2.48(17)3.047(12)122(15)+x, +y, −1 + z
O2-H2B…Br10.888(10)2.45(2)3.314(5)164(6)+x, 1/2 − y, −1/2 + z
Table 3. Close contacts and their distances for the [Mn(MBPT)Br(H2O)2]ClO4 complex based on Hirshfeld calculations.
Table 3. Close contacts and their distances for the [Mn(MBPT)Br(H2O)2]ClO4 complex based on Hirshfeld calculations.
ContactContact Distance (Å)ContactContact Distance (Å)
Br1…H1B2.472H2A…O52.437
Br1…H2B2.360H11…O72.545
Br1…H32.843C7…O63.182
H1A…O51.980C8…O63.196
H2A…O42.533C8…O43.022
Table 4. The M(II)-MBPT affinity of the studied complexes a.
Table 4. The M(II)-MBPT affinity of the studied complexes a.
Complex[M(II)-L]2+MBPTM(II)Eint b
[Mn(MBPT)Br(H2O)2]ClO4; 1−1105.0853−1001.6449−103.0413−250.4392
[Co(MBPT)(H2O)2Cl]Cl; 2−1146.1391−1001.5828−144.0981−287.5251
[Co(MBPT)(NO3)2]; 3−1146.2080−1001.6447−144.0981−291.9177
[Co(MBPT)(H2O)3](ClO4)2. H2O; 4−1146.2086−1001.6433−144.0981−293.1727
[Co(MBPT)(H2O)3](NO3)2.H2O; 5−1146.2108−1001.6463−144.0981−292.6707
[Ni(MBPT)(H2O)2 Cl]Cl; 6−1170.4113−1001.6402−168.2207−345.3815
[Ni(MBPT)(H2O)3](NO3)2.1/2 H2O; 7−1170.4110−1001.6221−168.2207−356.5826
[Ni(MBPT)(H2O)3](ClO4)2. H2O; 8−1170.4284−1001.6424−168.2207−354.7314
[Zn(MBPT)(H2O)Cl] ClO4; 9−1066.6811−1001.6460−64.5754−288.4663
[Zn(MBPT)(NO3)2]; 10−1066.6785−1001.6447−64.5754−287.6506
a All values in a.u. except Eint in kcal/mol; b Eint = EComplex − (EMetal + ELigand).
Table 5. Crystal data for [Mn(MBPT)Br(H2O)2]ClO4.
Table 5. Crystal data for [Mn(MBPT)Br(H2O)2]ClO4.
CCDC2155139
Empirical formulaC14H21N7O7MnClBr
F.Wt569.68 g/mol
T296(2) K
λ0.71073 Å
Crystal systemMonoclinic
Space groupP21
Unit cell dimensionsa = 8.3217(4) Å
b = 33.3369(16) Å
c = 8.2814(4) Å
β = 97.981(2)°
V2275.17(19) Å3
Z4
ρcalc.1.663 g/cm3
μ2.503 mm−1
2Θ range5.092 to 56.54°
Reflections collected42,472
Independent reflections5596 [Rint = 0.0671, Rsigma = 0.0520]
Goodness-of-fit on F21.12
Final R indexes [I ≥ 2σ (I)]R1 a = 0.0774, wR2 b = 0.1820
Final R indexes (all data)R1 a = 0.1024, wR2 b = 0.1930
Largest diff. peak and hole1.38 and −1.31 e Å−3
a R1 = Σ||Fo| − |Fc||/Σ|Fo|. b wR2 = {Σ[w(Fo2 − Fc2)2]/Σ[w(Fo2)2]}1/2.
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Khattab, S.M.; Altowyan, M.S.; El-Faham, A.; Barakat, A.; Haukka, M.; Abu-Youssef, M.A.M.; Soliman, S.M. A New Bromo-Mn(II) Complex with 1,3,5-Triazine Derivative: Synthesis, Crystal Structure, DFT and Biological Studies. Inorganics 2024, 12, 284. https://doi.org/10.3390/inorganics12110284

AMA Style

Khattab SM, Altowyan MS, El-Faham A, Barakat A, Haukka M, Abu-Youssef MAM, Soliman SM. A New Bromo-Mn(II) Complex with 1,3,5-Triazine Derivative: Synthesis, Crystal Structure, DFT and Biological Studies. Inorganics. 2024; 12(11):284. https://doi.org/10.3390/inorganics12110284

Chicago/Turabian Style

Khattab, Sara M., Mezna Saleh Altowyan, Ayman El-Faham, Assem Barakat, Matti Haukka, Morsy A. M. Abu-Youssef, and Saied M. Soliman. 2024. "A New Bromo-Mn(II) Complex with 1,3,5-Triazine Derivative: Synthesis, Crystal Structure, DFT and Biological Studies" Inorganics 12, no. 11: 284. https://doi.org/10.3390/inorganics12110284

APA Style

Khattab, S. M., Altowyan, M. S., El-Faham, A., Barakat, A., Haukka, M., Abu-Youssef, M. A. M., & Soliman, S. M. (2024). A New Bromo-Mn(II) Complex with 1,3,5-Triazine Derivative: Synthesis, Crystal Structure, DFT and Biological Studies. Inorganics, 12(11), 284. https://doi.org/10.3390/inorganics12110284

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