Metal Chelates of Sulfafurazole Azo Dye Derivative: Synthesis, Structure Affirmation, Antimicrobial, Antitumor, DNA Binding, and Molecular Docking Simulation

A series of divalent and one trivalent metal chelates of the azo ligand resulting from coupling of sulfafurazole diazonium chloride with resorcinol have been designed and synthesized. Structure investigation of the isolated chelates have been achieved by applying spectroscopic and analytical tools which collaborated to assure the formation of the metal chelates in the molar ratios of 1L: 1M for Ni(II), Co(II), and Fe(III) chelates, where Cu(II) and Zn(II) complexes formed in the ratio 2L : 1M. The geometrical arrangement around the metal canters was concluded from UV-Vis spectra to be octahedral for all metal chelates. The attachment of the ligand to the metal ions took place through the azo group nitrogen and o-hydroxyl oxygen through proton displacement leading to the ligand being in monobasic bidentate binding mode. Antimicrobial and antitumor activities of the interested compounds have been evaluated against alternative microorganisms and cancer cells, respectively, in a trial to investigate their extent of activity in addition to docking studies. The mode of interaction of the compounds with SS-DNA has been examined by UV-Vis spectra and viscosity studies.


Introduction
Te class, sulfonamide, which is produced by switching out various functional groups, can exhibit a broad range of diverse therapeutic and pharmacological vitalities [1][2][3][4]. Te staggering number of publications has focused on sulfonamide complexes due to the strong propensity of sulfonamides to ligate metal ions in a variety of ways [5][6][7][8]. Te tendency of sulfonamides to function as ligands is thought to be caused by the -SO 2 -NH site's acidic activity, which leads to the development of anionic donors reinforced by having O, S, and/or N atoms. Te stereochemical requirements for various confgurations, such as monomeric, dimeric, and polymeric structures, are met by such theme settings [9,10]. In addition, the aromatic amino group, which is the other basic part of sulfonamides, is responsible for the chemical polarity of such compounds since it can function as an excellent coordination centre. However, what appears more signifcant is that this moiety is a reactive site through which sulfonamides can be largely modifed generating ligands to obtain a vast number of complexes with biological importance [11,12].
Te sulfonamide compounds' azo dye derivatives are also useful as possible ligands for a variety of metal ions [13][14][15][16]. Te antimicrobials made of azo sulfonamides were the frst efective chemotherapeutic medications that could be administered systemically to treat bacterial infections in humans. A class of azo dye stufs with a sulfonamide functional group is common. Tese azo sulfonamide dyes were developed as potential antibacterial medications [13]. Furthermore, heterocyclic azo dyes have been crucial to the improvement of the branch coordination chemistry. Tese substances' signifcance may stem from their biological potency and analytical uses [17]. Teir formed metal complexes demonstrated fantastic applications in biological systems and the dying process [18,19]. Analytical detection of several metallic elements in actual samples has been also performed using such compounds [20,21]. Moreover, the contribution of such class of compounds in spectroscopic studies and investigation of azo dyes and their metal complexes is considerable [5,13,[15][16][17][18][19][20][21][22].
Since cellular DNA and proteins are practically all bioactive medicines' extreme targets, the step that follows the production of a new compound intended for biological applications is to examine its activity in DNA and protein binding [22]. Furthermore, the method by which compounds bind to DNA may be important for developing new and better medications that can recognize a particular DNA location [23]. It is possible for compounds including metal complexes to bind to DNA covalently (by substituting a labile ligand in the structure of metal chelates with a nitrogen base of DNA such as guanine N7), through noncovalent bonds (by intercalation, electrostatic, or groove binding), or by a combination of the two types [24,25]. For the intercalation mode of binding, there are two main modes, classical and threading intercalation. Classical intercalators are those compounds which attach to duplexes of DNA basically through all of their aromatic system implemented between GpG base pairs form the intercalation site top and bottom. On the other hand, in threading intercalators, the minor and major grooves of DNA are simultaneously occupied by the intercalators. Metal chelates which interact with DNA via intercalation can form both classes [26].
Preparation of metal complexes (as new drugs) in the nanometre form displays great importance in increasing the efciency of drug absorption by human cells while minimizing the amount of required active material (i.e., less amount and higher absorption), which in turn reduces additives, medicines, and also reduces the side efects of chemical additives [27]. So, based on the previous facts, the main theme of this research is the synthesis of novel metal chelates of the sulfonamide azo ligand that is obtained by coupling of sulfafurazole diazonium chloride with resorcinol. Te structures, mode of bonding, and geometry of the synthesized complexes have been afrmed using the analytical and spectral tools in addition to X-ray and TEM analysis to assign their morphology and particle size range. Bioassay evaluation of the synthesized compounds against alternative types of bacteria, fungi, and the tumor cell lines A-549 (human lung carcinoma cancer cell line) and Panc-1 (pancreatic carcinoma) have been also assured with theoretical calculations applying molecular docking simulation. Electronic absorption titration and viscosity measurements have been used to assign how the obtained compounds bind to SS-DNA.

Synthesis of H 3 PIBS Metal
Chelates. Cu(II), Ni(II), Co(II), Fe(III), and Zn(II) chelates of H 3 PIBS ligand have been isolated following the next procedures: 1 mmol of CuCl 2 ·2H 2 O (0.17 g), NiCl 2 ·6H 2 O (0.237 g), CoCl 2 ·6H 2 O (0.236 g), FeCl 3 (0.162 g), and Zn(NO 3 ) 2 ·6H 2 O (0.297 g) dissolved in 15 mL of hot MeOH were separately and slowly poured into 30 mL solution hot methanolic containing 1 mmol of H 3 PIBS ligand (3.88 g) and 3 drops of the alkaline triethylamine. Te formed mixtures were heated with refux for nearly 2 hours within which dark products were noticed clearly. Filtration was used to separate the generated products, and then methanol and ether were used for their washing. Te precipitates were then desiccated over dehydrated CaCl 2 in a vacuum. Tin layer chromatography (TLC) was used to verify the purity of the metal chelate that was produced.

Analytical, Physical Methods and Instrumentations.
All of the chemicals utilized, which are analytical grade and used directly without undergoing purifcation, were provided by Sigma-Aldrich Company. All data about the tools and methods used to confrm the compounds' structures are provided in the supplementary fle (Section S1).

2.4.
Antibacterial and Antifungal Evaluation. Antimicrobial and antifungal evaluation of the target complexes and their ligand have been carried out contra the strains Staphylococcus aureus (S. aureus), Bacillus cereus (B. cereus), Escherichia coli (E. coli), Salmonella typhi (S. typhi), Aspergillus favus (A. favus), and Candida albicans (C. albicans) using the well difusion method [29]. Te applied procedures in detailed are shown in Section S2 (supplementary fle).

Cytotoxic Evaluation.
Te target chelates and their ligand have been alsoexamined for their cytotoxicity assay against the human lung cancer cell lines (A-549) and pancreatic carcinoma (Panc-1) applying the reported method [30,31], which have been presented in detail in Section S3 (supplementary fle).
2.6. Molecular Docking Simulation. Te software used for docking simulation is MOE-Dock 2014 [32]. Te proteins which have been applied for such study are receptors of Staphylococcus aureus adhesion protein (PDB ID: 4m01) in addition to caspase-3 (PDB ID: 2XYG). Docking studies details are shown in supplementary data (Section S4).

DNA-Binding Modes.
To assess the DNA-binding propensity of the compounds of interest in the current study, salmon sperm DNA (SS-DNA) was used. Spectroscopic analysis was used to confrm that there are no proteins involved in the DNA structure. Te ratio of absorbance at wavelengths 260 and 280 nm (A260/A280) has been determined to be in the range 1.8-1.9 [33]. Absorption spectroscopy and viscosity measurements have been employed as the investigative tools for determining how the compounds of interest bind to DNA. Section S5 of the supplementary fle contains details about the experiment's procedures.

Results and Discussion
3.1. 1 H-NMR Spectra. Te ligand's, H 3 PIBS, 1 H-NMR spectra were recorded in d 6 -DMSO and in the presence of D 2 O using the internal standard tetramethylsilane (TMS) (Figures 2 and S1). Te main spectrum recorded in d 6 -DMSO have three singlet signals at 12.36,10.60, and 10.47 corresponding to the two hydroxide protons and NH protons, respectively [33]. Tese three signals are entirely missed by addition of D 2 O assuring. Te eight aromatic protons appeared in the range 7.78 − 6.33 ppm. Te two methyl protons with their 6 hydrogen atoms appeared as sharp singlet signals at 1.57 (attached to the C�C group) and 2.05 ppm (attached to C�N) [34].

Molar Conductivity and Complexes' Stoichiometry.
Te azo ligand H 3 PIBS and its fve complexes, H 2 PIBS-Cu, H 2 PIBS-Ni, H 2 PIBS-Co, H 2 PIBS-Fe, and H 2 PIBS-Zn, aforded elemental analysis results that are remarkably comparable with the ascribed molecular formulae. Although H 2 PIBS-Cu and H 2 PIBS-Zn chelates have been synthesized in the molar ratio 1 : 1 (M : L), as illustrated in Table 1, the obtained analytical results confrmed the formation of these complexes in the molar ratio 1 : 2 (M : L). Te rest of compounds have been confrmed to be constituted in the molar ratio 1 : 1. Te information received from molar conductance measurement using a concentration of 10 − 3 M in DMF for each chelate showed molar conductance values inside the range 25.1-33.9 Ω − 1 ·cm 2 ·mol − 1 which are matching with nonelectrolytic metal chelates [35]. Te 2 ] afording high stability in air without any colour change. All the compounds are largely soluble in high polarity solvents as DMF and DMSO but hard to dissolve or insoluble in nonpolar or low polarity solvents.

EI-Mass Spectra.
Te assignment of the molecular weight of H 3 PIBS ligand and its chelates has been concluded from the mass spectral investigation. As interpreted in

FTIR and Binding Mode Assignment.
By matching the FTIR spectra of the fve synthesized metal complexes with that of H 3 PIBS, it is possible to identify the coordinating function groups in the ligand to the metal canters. Coordinating function groups frequently exhibit changes in the position and/or intensity. Upon chelation, it is also possible for some bands to vanish. Table 2 lists the most signifcant infrared bands of H 3 PIBS and its complexes together with their assigned values.
According to the data shown in Table 1, the bands at 3485 and 3391 cm − 1 in H 3 PIBS spectra were assigned to the stretching vibrations of the OH groups. NH stretching vibration band appeared at 3238 cm − 1 [36]. Te isoxazole azomethine stretching vibration peak appeared at 1596 cm − 1 , whereas the azo group had its peak appeared at 1503 cm − 1 . Te two bands apparent at 1375 and 1163 cm − 1 , SO 2 group, provided two peaks for the asymmetric and In the spectra of metal complexes H 2 PIBS-Cu, H 2 PIBS-Ni, H 2 PIBS-Co, H 2 PIBS-Fe, and H 2 PIBS-Zn, the broad band appeared within the extent 3369-3456 cm− 1 had assigned to the stretching vibration of OH of water molecules incorporated in the complexes structures which overlapped with the stretching vibration band of uncomplexed OH group. In the spectra of all chelates, the band appearing in the extents 4211-4240, 1361-1383, and 1162-1178 cm − 1 had been allocated to the stretching vibration of NH, asymmetric stretching of SO 2 , and symmetrical stretching of SO 2 group, respectively. Although these bands are not taking part in coordination with the metal centres, the shift in their positions, in some cases, refers to their involvement in the H-bong formation [37] and/or the diferent locative orientation of the S=O group in the complex with that of the free ligand [38]. Isoxazole ring's azomethine that appeared in the ligand spectra at 1596 cm − 1 has appeared in the complexes' spectra in the extent of 1595-1598 cm − 1 and thus providing a little variation in the band positions in relation to their locations in the free ligand. Such behaviour is consistent with the group nonengaging in chelation to the metal core.
Oppositely, the two bands corresponding to v(N�N) and  [37] provides additional evidence that nitrogen and oxygen atoms are involved in complex formation.

Termogravimetric Results.
Te thermal analysis technique, which provides crucial details on compounds' thermal properties, steps of thermal degradation, types of intermediates, and residual products, is one of the most useful approaches used to predict the molecular structure and stability of compounds. Recognizing the anionic groups linked to the metal centre as well as the quantity and kind of water and/or organic solvent molecules that attached to the metal centre is necessary. Te TG thermograms of H 3 PIBS metal chelates are shown in Figure 4. Table 3 also shows the analysis results of each thermogram. It is evident from the TG thermograms that the complexes under study degraded in 4 phases as shown by H 2 PIBS-Ni and H 2 PIBS-Fe complexes or 5 phases as for H 2 PIBS-Cu, H 2 PIBS-Co, and H 2 PIBS-Zn complexes. For H 2 PIBS-Cu, the frst stage appeared in the range 25-105°C within which lattice water molecules are lost. Te second stage successively appeared and extended to 183°C, in which coordination water was missed. For the rest of complexes, the frst stage extended       from 25 to 188°C, in which coordinated water molecules are lost, whereas the second step appeared in the range 113-392°C. Within this stage, coordinated chloride ions are lost alongside with a part of the organic ligand. After the second step, the decomposition of the organic ligand continued successively within two or three stages up to the end of the applied heating temperature, i.e., 800°C.

Geometrical Arrangements via UV-Vis Spectra and
Magnetic Moment. Te produced compounds' UV-Vis spectra were obtained by dissolving the compounds in the DMSO solvent and also by following the Nujol mull process, in the 200-800 nm range; the assigned bands are collected in Table 4 and presented in Figure 5. From the spectra of the ligand H 3 PIBS, the band appeared in the Nujol mull spectrum at 253 nm and in DMSO at 256 and 267 nm corresponding to the transition of the type π ⟶ π * in the phenyl rings. Te bands appearing at 275 and 395 nm in DMSO and at 328 nm in Nujol mull spectrum assigned to π ⟶ π * and n ⟶ π * transitions in the C�N group, respectively. Te bands appearing at 435 and 523 nm in Nujol mull and at 443 nm in DMSO assigned to n ⟶ π * transitions of N�N and SO 2 groups.
Te divalent Cu chelate, H 2 PIBS-Cu, exhibited the low intensity band appearing in the Nujol mull spectrum at 723 nm assigned to 2 E g ⟶ 2 T 2g transition documented for octahedral Cu(II) complexes [24]. Te two bands appearing at 440 and 420 nm in DMSO and Nujol mull, respectively, assigned to MLCT spectra [24]. Upon measuring the magnetic moment (μ ef ), the obtained value was calculated to be 1.94 B.M characteristic for monomeric Cu(II) complexes afording no Cu-Cu interaction [39].
For the Co(II) complex H 2 PIBS-Co, the bands appearing in the DMSO spectrum at 439 and 530 nm and in the Nujol mull spectrum at 449 and 549 nm are assigned to 4 T 1g (F) ⟶ 4 T 1g (P) and 4 T 2g (F) ⟶ 4 A 2g transitions, respectively. Tese two transitions combined with the transition of the type 4 T 1g (F) ⟶ 4 T 2g that corresponded to the low intensity band appearing in the Nujol mull spectrum at 692 nm are characteristic to cobalt(II) octahedral chelates [25]. Magnetic moment of 4.39 B.M has been obtained that is distinctive for high-spin octahedral Co(II) chelates.
For the trivalent Fe complex, H 2 PIBS-Fe, the three bands that appeared in the Nujol mull spectrum at 465, 544, and 677 nm documented to the transitions of the type 6 A 1g (S) ⟶ 4 A 1g (G), 6 A 1g (S) ⟶ 4 T 2g (G), and 6 A 1g (S) ⟶  Such compound shows just bands in visible region due to charge transfer (CT). So, the obtained spectra aforded the visible bands at 400 and 439 nm in DMSO and at 456 and 502 nm in Nujol mull that was assigned to CT transition [33,34].

X-Ray Difraction (XRD) Studies.
In light of recent developments in technology and knowledge related to material science, one of the most signifcant techniques for providing structural microcrystalline details regarding substances being fulflled is X-ray powder difraction [40]. As a result, metal complexes H 2 PIBS-Cu, H 2 PIBS-Ni, H 2 PIBS-Co, H 2 PIBS-Fe, and H 2 PIBS-Zn that were under examination and the free ligand H 3 PIBS difraction patterns were both performed within wide scattering angle range (10°< 2θ > 80°) and presented in Figures 6, S6, and S7. Te free ligand pattern is entirely diferent from the pattern of the inspected metal complexes that promote complex formation and confrm that there are no smeared contaminants or initiating reactants [41]. Well-defned crystal structures were indicated by the X-ray difraction patterns obtained for H 3 PIBS and complex H 2 PIBS-Cu, and good crystallinity was observed for complexes H 2 PIBS-Fe and H 2 PIBS-Zn with completely diferent difraction patterns, whereas complexes H 2 PIBS-Ni and H 2 PIBS-Co appeared completely amorphous. Debye-Scherrer equation based on FWHM for the characteristic peak was used to determine the crystal size [42], ligand H 3 PIBS, complexes H 2 PIBS-Cu, H 2 PIBS-Fe, and H 2 PIBS-Zn, displayed average crystallite sizes 17.2, 2.4, 43.9, and 6.1 nm, respectively. Te amorphous form of the complexes H 2 PIBS-Ni and H 2 PIBS-Co may be an indication of the uneven arrangement of the solid constituents during the precipitation process. If the complexation process is swift and/or the generated chemical is cooled quickly, this amorphous state will predominate. Furthermore, a crystal lattice cannot hold many of the complex's structural components. Tey precipitate in a phase that is primarily amorphous. Te examined compounds' amorphous nature may be the reason for the aggregates' unusual small sizes, which were confrmed by TEM investigation to be in the nanometric range. Te innovative nanosized  obtained compounds can generate a great deal of anxiety due to their unique functional characteristics and a vast array of potential technological applications, which include enhanced catalysis, microelectronics, optics, and chemical biosensors [27].

TEM Images.
Transmittance electron microscopy (TEM) is one of the most common techniques to study a wide range of fascinating nanosized materials. It is a method that is usually employed to look at the shape and dimensions of solid materials. Terefore, the particle sizes and crystallinities of the produced complexes were further investigated by the TEM technique. Images captured by the transmittance electron microscope in bright feld are shown in Figures 7, 8, and S8-S10 demonstrating that the samples are made up of tiny, diferent-sized nanoparticles except for complex H 2 PIBS-Zn.
It is obvious from these images that the metal complex powders are composed of tiny, spherical-like particles (either regular or not). In addition, it was found that the particle sizes of metal complexes ranged from 14.2 to 51.11 nm for H 2 PIBS-Cu, 26 Terefore, it is hypothesized that the biological efciency of these novel synthetic chelates at these nanometric sizes is greater than that of their bulk analogues. Te new functional characteristics of nanoscale metal complexes and their numerous potential technological applications have the potential to generate a great deal of interest [27].

Molecular Docking Simulation.
Structure-based drug designs are an essential part of most industrial drug discovery programs. Terefore, to primarily examine the extent of the synthesized compounds' biological efcacy, their Te complete profle of the investigated substances' interactions with 4m01 is depicted in Table 5 and presented in Figures 9, as an example. Examination of the data shown in Table 5 indicates the relative strong tendency of the target compounds for docking on 4m01 which have been concluded from docking score values. Tese values were found to be in the range − 4.9221 − − 7.0350 kcal/mol with. For 4m01, the strongest binding was aforded by H 2 PIBS-Cu complex with docking score of − 7.0350 kcal/mol. Te least binding ability was observed by H 2 PIBS-Ni with docking score values of − 4.9221 kcal/mol to 4m01. Te binding ability of the tested compounds to 4m01 follow the order (form the docking score value):

H 2 PIBS-Cu > H 2 PIBS-Zn > H 3 PIBS > H 2 PIBS-Fe > H 2 PIBS-Co > H 2 PIBS-Ni.
Te value of bond lengths for the majority of interactions that were found to be, in most cases, smaller than 3.5Å, is the reported range for true docking track [33]. Tese values led to the conclusion that the investigated compounds had real docking tracks to both 4m01 and 4ynt. Te collected information showed that most of the investigated compounds may have promising activity and deserve further practical examination for their biological activities, especially H 2 PIBS-Zn, H 2 PIBS-Cu, and H 3 PIBS.
Also, to assign the extent of the antitumor activity of the tested compounds, the interaction of the compounds under study with caspase-3 (PDB ID: 2XYG) has been evaluated, Figure 10. Te docking score values are found to be inside the range − 5.7176 to − 7.7365 kcal/mol. Te strongest binding was aforded by H 2 PIBS-Cu complex with docking score of − 7.7365 kcal/mol followed by H 2 PIBS-Zn complex with docking score of − 7.6576 kcal/mol. Te binding ability of the tested compounds to 2XYG follow the order (form the docking score value): H 2

PIBS-Cu > H 2 PIBS-Zn > H 2 PIBS-Fe > H 2 PIBS-Ni > H 2 PIBS-Co > H 3 PIBS
By docking the cocrystallized ligand of 4ynt, the docking program used in the current study has been validated. Te optimal position was chosen and aligned with the docked pose of the same ligand to have the best binding energy, ligand-receptor interactions, and active site residues ( Figure S11). Te employed docking program performed well, with the RMSD being 1.546 [33].     , and 20 mm inhibition zones against unicellular fungus (C. albicans) greater than amphotericin-p (13 mm). Te chosen species exhibit a variety of microorganisms, such as unicellular and multicellular fungi, as well as Gram-positive and Gram-negative bacteria [43]. In most cases, the presence of metal ions, which are more hypersensitive to microbial cells than the organic chelating agent, can be blamed for the increased antimicrobial action during chelate formation [44]. Te increased lipophilicity during complexation may also be the reason for the metal chelates' stronger efects. Te coordinated metal ions may inhibit the activity of cellular enzymes or result in harmful interactions between cellular components. Either variations in the ribosomes in microbial cells or the impermeability of the cells of microorganisms cause obvious alterations in the activity of various complexes across diferent organisms [45]. According to the information at hand in the present investigation, the investigated ligands and their complexes show signifcant promise for developing into novel, extremely potent, broadspectrum bactericides and fungicides.   of platinum(II) complexes, particularly those that target genomic DNA, such as cisplatin, carboplatin, and oxaliplatin. A platinum drug is given, either alone or in combination, to around 50% of cancer patients receiving chemotherapy. Platinum drugs, despite being essential in cancer chemotherapy, have substantial drawbacks, such as a systemic dose-related toxicity, limited spectrum of antitumor efectiveness, and a propensity to cause drug resistance, which usually leads to treatment failure [46]. In response to these observations, there is a lot of interest in researching nonplatinum metal-based drugs as an efective replacement [41]. In this concern, we sought to assess the new compounds' ability to inhibit the growth of human pancreatic carcinoma (Panc-1) and lung carcinoma (A-549) cell lines. Te value of growth inhibitory concentration (IC 50 ), which represents the concentration of the compounds needed to produce a 50% inhibition of cell growth after incubation for 72 hours, parallel to untreated controls, was used to represent the cytotoxicity results. Te survival curve of the tumor cell line, which was plotted between concentration and % cell viability, was used to derive the IC 50 values. Each test substance was diluted in a variety of quantities (1.56, 3.125, 6.25, 12.5, 25, 50, and 100 μg/ml) and presented in Figure 11, and Table S1 shows the results of IC 50 concentrations of synthetic compounds in comparison to the widely used anticancer medication vinblastine sulphate (VS) as standard which displayed IC 50 values 24.6 and 4.68 μg/ml towards lung and pancreatic carcinoma cells, respectively. Untreated cells were used as a control, and each data point was expressed as the value ± SD and represented the average of three separate studies [16]. Among the tools which frequently applied to assign the mode of DNA binding with chemical compounds, UV-Vis titration spectra are considered a considerable one where the compound's absorption peak may alter in its position or strength as a result of its interaction with the DNA molecule [16,47]. Te spectral feature that is frequently observed in the case of intercalation binding is the absorbance decrease of the compounds' spectral peak (hypochromism) upon adding increasing amounts of DNA, which is caused by π ⟶ π * stacking interaction. Te spectral peak may also undergo red-shift (bathochromism) in case of DNA duplex stabilization. Te other spectral which probably observed is the absorbance increases of the compounds' spectral peak (hyperchromism), which can be explained by the external binding of the compounds and DNA, it is sometimes accompanied by blue shift of the spectral peaks (hypsochromic shift) [24].
Measurement of UV-Vis spectra of the compounds presented in the current study have been carried out using fxed concentration of the ligand or its complexes that was taken as 50 μM, and the concentration of the used SS-DNA was changed in the range of 0-40 μM. Te spectra were recorded for each addition of DNA. By adding an equal amount of SS-DNA to the test and reference solutions, DNA absorbance was cancelled. Following these procedures, the absorption spectra of H 3 PIBS, H 2 PIBS-Cu, H 2 PIBS-Ni, H 2 PIBS-Co, H 2 PIBS-Fe, and H 2 PIBS-Zn were measured; the spectra are illustrated in Figures 12, 13, and S12-S15 As seen in these fgures, the absorption peaks illustrated at λ equal to 262, 369, 378, 390, and 396 nm for H 3 PIBS, H 2 PIBS-Cu, H 2 PIBS-Co, H 2 PIBS-Fe, and H 2 PIBS-Zn, successively, aforded hyperchromic behaviour. For H 2 PIBS-Ni, the peak appeared at 409 nm showed hypochromic behaviour. Te former performance matches with the tight compounds binding to DNA, and its interactions with compounds cause DNA to stabilize, which is likely due to electrostatic contact or partial unravelling of the DNA helix structure, exposing additional DNA bases. Tese characteristics are signs of strong complex binding to DNA. In addition, after the complex-DNA interaction, the hyperchromic efect refects the equivalent changes in the secondary structure of DNA in its conformation [33,48].
Te value of binding constant (K b ), which can be obtained by application of Wolfe-Shimmer equation [48], is  Several behaviours are probable to take place for the viscosity of DNA solution upon binding with chemical compounds. Te viscosity of the DNA solution is largely increased upon increasing the concentration of chemical compounds in a behaviour familiar to the classical intercalation mode of binding for such binding to occur, a big distance between the base pairs is needed leading to an enhancement of the DNA solution viscosity [49]. Tis behaviour is a common behaviour for classical intercalator such as EB [50]. Another typical behaviour is the slight rise/ decrease or even no change in DNA viscosity with raising the compounds' concentration that may be due to bending or kinking in the DNA double helix. Tis behaviour reduces the efective DNA length and supports nonclassical and/or partial intercalation interaction in the DNA grooves [51,52]. viscosity upon gradually increasing the investigated compounds' concentrations, the viscosity of all compounds exceeds that of EB demonstrating that the predominant way of binding for all compounds with SS-DNA is intercalative.

Conclusion
Cu(II), Ni(II), Co(II), Fe(III), and Zn(II) complexes of the azo dye formed by the coupling of sulfafurazole diazonium chloride with resorcinol have been isolated. Structure investigation of the isolated chelates have been obtained through spectroscopic and analytical tools, which collaborated to assure the formation of the metal chelates in the molecular formulae, [Cu(H 2 PIBS) 2  , where H 2 PIBS abbreviates the monodeprotonated ligand, and hence indicating the formation of 1L: 1M stoichiometry for Ni(II), Co(II), and Fe(III) chelates, where Cu(II) and Zn(II) complexes formed in the ratio 2L : 1M. Te geometrical arrangement around the metal canters was concluded from UV-Vis spectra to be octahedral for all metal chelates. Te linkage of ligand to the metal centre occurred through the azo group nitrogen and o-hydroxyl oxygen through proton displacement, and thus the structures of the metal chelates are formulated in Scheme 1. Te antimicrobial activity of the compounds under interest has been evaluated against alternative microorganisms covering the Gram positive, Gram negative bacteria, and fungi classes of microorganisms. Te obtained results showed that the ligand H 3 PIBS and its complexes H 2 PIBS-Cu and H 2 PIBS-Zn aforded the highest activity against the alternative tested strains. Such data are in good accordance with the molecular docking simulation of the interested compounds with the receptor of Staphylococcus aureus adhesion protein (PDB ID: 4m01). Te antitumor activity of the compounds under study has been evaluated against the tumor cell lines A-549 (human lung carcinoma cancer cell line) and Panc-1 (pancreatic carcinoma), and the results obtained showed that enhanced antitumor activity for the metal complexes in comparison with the parent ligand. Promising activity has been observed for the Cu(II) chelate with IC 50 of 12.26 and 13.43 μg/ml against A-549 and Panc-1 cell lines, respectively, that is in accordance with docking studies with caspase-3 (PDB ID: 2XYG). Te mode of interaction of the compounds DNA has been examined by UV-Vis spectra and viscosity studies indicating the intercalation mode of binding with SS-DNA, which has been concluded from the K b values and the enhancement of DNA solution viscosity upon adding diferent concentrations of the compounds under interest.

Data Availability
Te data that support the fndings of this study are available from the corresponding authors upon reasonable request.