Main group metal complexes of semicarbazones and thiosemicarbazones. A structural review

Synthesis, structures, and DFT analysis of gold complexes containing a thiosemicarbazone ligand

A mixture of E,Z-thiosemicarbazone (TSC) allows the formation of two Au(i) complexes; the reaction of TSC with KAuCl4 yields two complexes in different solvents.

Copper(I) and silver(I) complexes of anthraldehyde thiosemicarbazone: synthesis, structure elucidation, in vitro anti-tuberculosis/cytotoxic activity and interactions with DNA/HSA

A reaction of copper(i) halides (X = I, Br, Cl) and silver(i) halides with 9-anthraldehyde thiosemicarbazone (9-Hanttsc, H1L) and triphenylphosphine produced halogen-bridged dinuclear complexes, [M2(μ2-X)2(η1-S-9-Hanttsc)2(Ph3P)2] (M = Cu, X = Cl, 1; Br, 2; I, 3; M = Ag, X = Cl, 4; Br, 5). A similar reaction of 9-anthraldehyde-N1-methyl thiosemicarbazone (9-Hanttsc-N1-Me, H2L) with Ph3P and silver(i) halides yielded sulfur-bridged dimers, [Ag2X2(μ2-S-9-Hanttsc-N1-Me)2(Ph3P)2] (X = Cl, 9; Br, 10), however with copper(i) halides insoluble compounds were formed, which upon the addition of one extra mole of Ph3P gave mononuclear complexes of the formula [CuX(η1-S-9-Hanttsc-N1-Me)(Ph3P)2] (X = Cl, 6; Br, 7; I, 8). All of the complexes have been characterized by elemental analysis, NMR (1H, 13C) spectroscopy and single crystal X-ray crystallography (2, 5, 6, and 9). Both the ligands (H1L and H2L) and their complexes (1-10) were tested for their anti-tubercular and anticancer activities. The interactions of the ligands and their complexes (copper and silver) with calf thymus DNA (ct-DNA) and human serum albumin (HSA) were examined through UV-visible and fluorescence spectroscopy. Results showed that copper complex 2 displayed strong interactions with ct-DNA and HSA having binding constant values of 6.66 × 104 M-1 and 3.28 × 104 M-1, respectively, followed by silver complex 10 which gave binding constant values of 4.60 × 104 M-1 and 3.06 × 104 M-1, respectively. All of the complexes also showed good interactions with DNA in docking studies.

Synthesis of Palladium(II) Complexes via Michael Addition: Antiproliferative Effects through ROS-Mediated Mitochondrial Apoptosis and Docking with SARS-CoV-2

Metal complexes have numerous applications in the current era, particularly in the field of pharmaceutical chemistry and catalysis. A novel synthetic approach for the same is always a beneficial addition to the literature. Henceforth, for the first time, we report the formation of three new Pd(II) complexes through the Michael addition pathway. Three chromone-based thiosemicarbazone ligands (SVSL1-SVSL3) and Pd(II) complexes (1-3) were synthesized and characterized by analytical and spectroscopic tools. The Michael addition pathway for the formation of complexes was confirmed by spectroscopic studies. Distorted square planar structure of complex 2 was confirmed by single-crystal X-ray diffraction. Complexes 1-3 were subjected to DNA- and BSA-binding studies. The complex with cyclohexyl substituent on the terminal N of thiosemicarbazone (3) showed the highest binding efficacy toward these biomolecules, which was further understood through molecular docking studies. The anticancer potential of these complexes was studied preliminarily by using MTT assay in cancer and normal cell lines along with the benchmark drugs (cisplatin, carboplatin, and gemcitabine). It was found that complex 3 was highly toxic toward MDA-MB-231 and AsPC-1 cancer cells with IC50 values of 0.5 and 0.9 μM, respectively, and was more efficient than the standard drugs. The programmed cell death mechanism of the complexes in MDA-MB-231 cancer cells was confirmed. Furthermore, the complexes induced apoptosis via ROS-mediated mitochondrial signaling pathway. Conveniently, all the complexes showed less toxicity (≥50 μM) against MCF-10a normal cell line. Molecular docking studies were performed with VEGFR2, EGFR, and SARS-CoV-2 main protease to illustrate the binding efficiency of the complexes with these receptors. To our surprise, binding potential of the complexes with SARS-CoV-2 main protease was higher than that with chloroquine and hydroxychloroquine.

An octadentate bis(semicarbazone) macrocycle: a potential chelator for lead and bismuth radiopharmaceuticals

A variant of 1,4,7,10-tetraazacyclododecane (cyclen) bearing two semicarbazone pendant groups has been prepared. The octadentate ligand forms complexes with Bi3+ and Pb2+. X-ray crystallography showed that the neutral ligand provides an eight-coordinate environment for both metal ions and intermolecular hydrogen bond interactions have influenced the coordination environments of both complexes in the solid state. NMR spectroscopy revealed a fluxional environment for both complexes. The ligand was radiolabeled with the α-emitting radioactive isotope 213Bi3+, which is used in systemic targeted radiotherapy. The resulting complex was stable in serum for at least 90 min (two decay half-lives). The Pb2+ complex has reasonably fast kinetics of formation (t1/2 = 20 min) at 25 °C and pH 7.4. The Bi3+ and Pb2+ complexes show kinetic stability in 1.2 M HCl (half-lives of 214 min and 47 min, respectively). This is the first description of a macrocycle bearing semicarbazone pendant groups and its utility in coordinating main group metals, specifically those with radiotherapeutic potential.

Synthesis of Novel Dinuclear N-Substituted 4-(Dimethylamino)benzaldehyde Thiosemicarbazonates of Rhenium(I): Formation of Four- and/or Five-Membered Chelate Rings, Conformational Analysis, and Reactivity

The reaction of fac-[ReX(CH₃CN)₂(CO)₃] (X = Cl, Br) with N-phenyl-[4-(dimethylamino)benzaldehyde] thiosemicarbazone (HL^A) or N-4-methoxybenzyl-[4-(dimethylamino)benzaldehyde] thiosemicarbazone (HL^B) under controlled synthetic conditions gave 4 mononuclear [ReX(HL)(CO)₃] (X = Cl, Br) and 16 dinuclear [Re₂L₂(CO)₆] compounds. These complexes were obtained as single crystals, and their structures were established by X-ray diffraction. The structural study of these dimers showed the formation of several solvates, the presence of linkage isomerism, and the stabilization of four- and/or five-membered chelate rings. The different ligand coordination modes (a new μ-κ²-S,N2:κ-N3 coordination mode for a thiosemicarbazone ligand was observed), the conformation of the thiosemicarbazone chain in each case, the formal symmetry of the dimers, and the role of the synthetic procedure in the stability of the different chelate rings were analyzed and are discussed. Theoretical calculations in the gas phase were performed for the dimers with the HL^A ligand in order to identify the thermodynamically most stable species. The behavior and structural stability of dimers in dimethyl sulfoxide and acetone solutions was investigated by ¹H NMR spectroscopy. The strength of the Re^I-L bond in solution was evidenced by the formation of [Re₂(L^NO₂)₂(CO)₆] and [Re(L^A)(py)(CO)₃] upon reaction of the corresponding dimer with concentrated nitric acid and pyridine, respectively.

Thiosemicarbazone Complexes of Transition Metals as Catalysts for Cross-Coupling Reactions

Catalysis of cross-coupling reactions under phosphane-free conditions represents an important ongoing challenge. Although transition metal complexes based on the thiosemicarbazone unit have been known for a very long time, their use in homogeneous catalysis has been studied only relatively recently. In particular, reports of cross-coupling catalytic reactions with such complexes have appeared only in the last 15 years. This review provides a survey of the research in this area and a discussion of the prospects for future developments.

Synthesis, Spectroscopic Characterization, Structural Studies, and In Vitro Antitumor Activities of Pyridine-3-carbaldehyde Thiosemicarbazone Derivatives

Eight new thiosemicarbazone derivatives, 6-(1-trifluoroethoxy)pyridine-3-carbaldehyde thiosemicarbazone (1), 6-(4′-fluorophenyl)pyridine-3-carbaldehyde thiosemicarbazone (2), 5-chloro-pyridine-3-carbaldehyde thiosemicarbazone (3), 2-chloro-5-bromo-pyridine-3-carbaldehyde thiosemicarbazone (4), 6-(3′,4′-dimethoxyphenyl)pyridine-3-carbaldehyde thiosemicarbazone (5), 2-chloro-5-fluor-pyridine-3-carbaldehyde thiosemicarbazone, (6), 5-iodo-pyridine-3-carbaldehyde thiosemicarbazone (7), and 6-(3′,5′-dichlorophenyl)pyridine-3-carbaldehyde thiosemicarbazone (8) were synthesized, from the reaction of the corresponding pyridine-3-carbaldehyde with thiosemicarbazide. The synthesized compounds were characterized by ESI-Mass, UV-Vis, IR, and NMR (1H, 13C, 19F) spectroscopic techniques. Molar mass values and spectroscopic data are consistent with the proposed structural formulas. The molecular structure of 7 has been also confirmed by single crystal X-ray diffraction. In the solid state 7 exists in the E conformation about the N2-N3 bond; 7 also presents the E conformation in solution, as evidenced by 1H NMR spectroscopy. The in vitro antitumor activity of the synthesized compounds was studied on six human tumor cell lines: H460 (lung large cell carcinoma), HuTu80 (duodenum adenocarcinoma), DU145 (prostate carcinoma), MCF-7 (breast adenocarcinoma), M-14 (amelanotic melanoma), and HT-29 (colon adenocarcinoma). Furthermore, toxicity studies in 3T3 normal cells were carried out for the prepared compounds. The results were expressed as IC50 and the selectivity index (SI) was calculated. Biological studies revealed that 1 (IC50 = 3.36 to 21.35 μM) displayed the highest antiproliferative activity, as compared to the other tested thiosemicarbazones (IC50 = 40.00 to >582.26 μM) against different types of human tumor cell lines. 1 was found to be about twice as cytotoxic (SI = 1.82) than 5-fluorouracile (5-FU) against the M14 cell line, indicating its efficiency in inhibiting the cell growth even at low concentrations. A slightly less efficient activity was shown by 1 towards the HuTu80 and MCF7 tumor cell lines, as compared to that of 5-FU. Therefore, 1 can be considered as a promising candidate to be used as a pharmacological agent, since it presents significant activity and was found to be more innocuous than the 5-FU anticancer drug against the 3T3 mouse embryo fibroblast cells.

Palladium (II) complexes with thione and thioalkylated thiosemicarbazones: Electrochemical, antimicrobial and thermogravimetric investigations

Four methoxy substitute salicylidene thiosemicarbazones were synthesized. The reaction of both thione and thioalkylated thiosemicarbazones with PdCl₂ in ethanol yields ONS-coordinated chelate complexes with general formula [Pd(L)Cl]. The structures of eight compounds were characterized by using analytical and spectroscopic methods. Electrochemistry of the Pd(II) complexes was studied using cyclic voltammetric technique. The CVs of the complexes were quite complicate because of some oxidative responses of the ligands which proceed by forming conjugated -N=CH-, -HC=CH- and -N=CH-HC=CH- groups. Two cathodic responses attributed to one electron reduction of Pd(II)/(I) and Pd(I)/(0) were observed for the central ion coordinated with S atom of H₃C-S- group whereas only one reduction peak appeared when the Pd(II) coordinated with S atom of >C=S group of thiosemicarbazone ligand. The latter also showed an additional anodic response assigned to Pd(II)/(III) oxidation. Thermogravimetric analysis (TGA) technique was used to investigate and compare the thermal properties of the ligands and their metal complexes. In vitro antimicrobial activity of thiosemicarbazones and their complexes was evaluated against four Gram-negative bacteria, three Gram-positive bacteria, and antifungal activity against three fungi.

Synthesis, molecular modelling, FT-IR, Raman and NMR characterization, molecular docking and ADMET study of new nickel(II) complex with an N4-tetradentate thiosemicarbazone

A new nickel(II) complex was synthesized by using S-propyl-thiosemicarbazide and 2-amino-3,5-dibromobenzaldehyde. The complex, obtained by the template effect of nickel ions, was structurally analysed by experimental and theoretical vibrational spectroscopy, NMR and density functional theory (DFT) calculations. By using DFT/B3LYP method with 6-311++G(d, p) basis set, the most stable molecular structure of the title molecule was calculated. The fundamental vibrational wavenumbers, IR and Raman intensities for the optimized structure of the molecule under investigation were determined and compared with the experimental vibrational spectra. The vibrational assignment was achieved using the calculated potential energy distributions of the vibrational modes. Moreover, the molecular electrostatic potential (MEP), the highest occupied molecular orbital (HOMO) and the lowest occupied molecular orbital (LUMO) energies were calculated, Molecular docking of the molecule was carried out against DNA in order to identify the potential inhibitory action of the title compound. The findings suggested that the aforementioned compound has a strong binding affinity to interact with DNA residues DT8, DC9, DG12, DG16, DA17, and DA18 through the intermolecular hydrogen bonds. Also the performed in silico ADMET analysis was the prediction of the synthesized molecule's pharmacokinetic and toxicity profile expressing good oral drug like actions and non-toxic nature. The complex has been shown to have the possibility to become a model molecule for drug development processes.Communicated by Ramaswamy H. Sarma.

Silver(I) metallodrugs of thiosemicarbazones and naproxen: biocompatibility, in vitro anti-proliferative activity and in silico interaction studies with EGFR, VEGFR2 and LOX receptors

Four new heteroleptic silver(I) complexes with the general formula [Ag(L1-4)(nap)] (1-4), where L1-4 =  2-(1-(4-substitutedphenyl)ethylidene)hydrazinecarbothioamide and nap = naproxen, have been synthesized and characterized. The geometric parameters determined from density functional theory and UV-Vis studies indicate distorted tetrahedral geometry around silver(I) ion. Fourier transform infrared (FT IR) spectra evidenced asymmetric bidentate coordination mode of carboxyl oxygen atoms of naproxen with silver(I) ion. The complexes are stable for 72 h and biocompatibility was analysed towards normal human dermal fibroblast cells, which showed non-toxic nature up to 100 ng/ml. In vitro anti-proliferative activity of the complexes by MTT assay was tested against three human cancerous cell lines and one non-tumorigenic human breast epithelial cell line (MCF-10a) in which the complex 4 exhibited enhanced activity. The morphological changes observed by acridine orange/ethidium bromide and Hoechst 33258 staining method reveal apoptosis-inducing ability of the complexes. The molecular docking studies suggest hydrogen bonding, hydrophobic and π-pair interactions with the active site of epidermal growth factor receptor, vascular endothelial growth factor receptor 2 and lipoxygenase receptors.

Synthesis, Crystal Structure, and Biological Activity of a Multidentate Calix[4]arene Ligand Doubly Functionalized by 2-Hydroxybenzeledene-Thiosemicarbazone

The design and synthesis of a novel tert-butyl-calix[4]arene functionalized at 1, 3 positions of the lower rim with two terminal 2-hydroxybenzeledene-thiosemicarbazone moieties is reported. The new ligand with multi-dentate chelating properties was fully characterized by several techniques: ESI-Mass spectroscopy, FT-IR, 1H-NMR, and single crystal X-ray diffraction. The solid state structure confirms that the calix[4]arene macrocycle has the expected open cone conformation, with two opposite phenyl rings inclined outwards with large angles. The conformation of the two alkoxythiosemicarbazone arms produces a molecule with a C2 point group symmetry. An interesting chiral helicity is observed, with the two thiosemicarbazone groups oriented in opposite directions like a two-blade propeller. A water molecule is encapsulated in the center of the two-blade propeller through multiple H-bond coordinations. The antibacterial, antifungal, anticancer, and cytotoxic activities of the calix[4]arene-thiosemicarbazone ligand and its metal derivatives (Co2+, Ni2+, Cu2+, and Zn2+) were investigated. A considerable antibacterial activity (in particular against E. coli, MIC, and MBC = 31.25 μg/mL) was observed for the ligand and its metal derivatives. Significant antifungal activities against yeast (C. albicans) were also observed for the ligand (MIC = 31.25 μg/mL and MBC = 125 μg/mL) and for its Co²⁺ derivative (MIC = 62.5 μg/mL). All compounds show cytotoxicity against the tested cancerous cells. For the Saos-2 cell line, the promising anticancer activity of ligand L (IC₅₀ < 25 μg/mL) is higher than its metal derivatives. The microscopic analysis of DAPI-stained cells shows that the treated cells change in morphology, with deformation and fragmentation of the nuclei. The hemo-compatibility study demonstrated that this class of compounds are suitable candidates for further in vivo investigations.

Metal complexes driven from Schiff bases and semicarbazones for biomedical and allied applications: a review

Schiff bases are versatile organic compounds which are widely used and synthesized by condensation reaction of different amino compound with aldehydes or ketones known as imine. Schiff base ligands are considered as privileged ligands as they are simply synthesized by condensation. They show broad range of application in medicine, pharmacy, coordination chemistry, biological activities, industries, food packages, dyes, and polymer and also used as an O2 detector. Semicarbazone is an imine derivative which is derived from condensation of semicarbazide and suitable aldehyde and ketone. Imine ligand-containing transition metal complexes such as copper, zinc, and cadmium have shown to be excellent precursors for synthesis of metal or metal chalcogenide nanoparticles. In recent years, the researchers have attracted enormous attention toward Schiff bases, semicarbazones, thiosemicarbazones, and their metal complexes owing to numerous applications in pharmacology such as antiviral, antifungal, antimicrobial, antimalarial, antituberculosis, anticancer, anti-HIV, catalytic application in oxidation of organic compounds, and nanotechnology. In this review, we summarize the synthesis, structural, biological, and catalytic application of Schiff bases as well as their metal complexes.

Chemical and biological studies of Re(I)/Tc(I) thiosemicarbazonate complexes relevant for the design of radiopharmaceuticals

Five thiosemicarbazones (H₂Lⁿ) derived from 4,6-diacetylresorcinol (n = 1-4) and salicylaldehyde (n = 5) have been synthesized and spectroscopically characterized. Single crystal X-ray diffraction studies on some of them show that the molecular structure is dominated by intramolecular hydrogen bonds involving the O(1)-H group of the resorcinol/salicylaldehyde group and the azomethinic nitrogen atom and sulfur atom of the thiosemicarbazone arm. All of the ligands react with fac-[ReBr(CO)₃(CH₃CN)₂] in the presence of NEt₃ to form the stable anionic complexes [NHEt₃][fac-[Re(Lⁿ)(CO)₃] (1-5). The thiosemicarbazonate ligand, as suggested by spectroscopic data and confirmed by X-ray diffraction, acts as a tridentate S,N,O system. The complexes are stable in solution for weeks, although other dimeric species were also detected by X-ray diffraction analysis. The reaction of fac-[^99mTc(CO)₃(H₂O)₃]⁺ with the appropriate ligand at 100 °C for 30 min yielded the complexes [fac-[^99mTc(Lⁿ)(CO)₃]^- (Tc1-Tc5). The radiochemical yield and purity were determined by HPLC and their chemical identity was ascertained by comparing their radiochromatogram with the chromatogram of the rhenium congeners (1-5). The results of biodistribution studies in mice on the five technetium compounds showed rapid blood clearance and fast liver uptake that slowly cleared into the intestines, a finding that indicates the hepatobiliary tract as the major excretory pathway. HPLC analysis of urine and blood serum samples from mice injected with the ^99mTc complexes confirmed their in vivo stability since the predominant radiochemical species had the same retention time as the corresponding injected compound.

Design and synthesis of methyl 2-{[4-phenyl-5-(pyridin-2-yl)-4H-1,2,4-triazol-3-yl]sulfanyl}acetate (phpy2NS) as a ligand for complexes of Group 12 elements: structural assessment and hydrogen-bonded supramolecular assembly analysis

The reaction of 2-cyanopyridine with N-phenylthiosemicarbazide afforded 2-[amino(pyridin-2-yl)methylidene]-N-phenylhydrazine-1-carbothioamide (Ham4ph) and crystals of 4-phenyl-5-(pyridin-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (pyph3NS, 1, C₁₃H₁₀N₄S). Crystals of methyl 2-{[4-phenyl-5-(pyridin-2-yl)-4H-1,2,4-triazol-3-yl]sulfanyl}acetate (phpy2NS, 2, C₁₆H₁₄N₄O₂S), derived from 1, were obtained by the reaction of Ham4ph with chloroacetic acid, followed by the acid-catalyzed esterification of the carboxylic acid with methyl alcohol. Crystals of bis(methanol-κO)bis(methyl 2-{[4-phenyl-5-(pyridin-2-yl)-4H-1,2,4-triazol-3-yl-κ²N¹,N⁵]sulfanyl}acetato)zinc(II)/cadmium(II) hexabromidocadmate(II), [Zn_0.76Cd_0.24(C₁₆H₁₄N₄O₂S)₂(CH₃OH)₂][Cd₂Br₆] or [Zn_0.76Cd_0.24(phpy2NS)₂(MeOH)₂][Cd₂Br₆], 3, and dichlorido(methyl 2-{[4-phenyl-5-(pyridin-2-yl)-4H-1,2,4-triazol-3-yl-κ²N¹,N⁵]sulfanyl}acetato)mercury(II), [HgCl₂(C₁₆H₁₄N₄O₂S)] or [Hg(phpy2NS)Cl₂], 4, were synthesized using ligand 2 and CdBr₂ or HgCl₂, respectively. The molecular and supramolecular structures of the compounds were studied by X-ray diffractometry. The asymmetric unit of 3 is formed from CdBr₃ and M(phpy2NS)(MeOH) units, where the metal centre M has a 76% occupancy of Zn^II and 24% of Cd^II. The M²⁺ centre of the cation, located on a crystallographic inversion centre, is hexacoordinated and appears as a slightly distorted octahedral [MN₄O₂]²⁺ cation. The Cd centre of the anion is coordinated by two terminal bromide ligands and two bridging bromide ligands that generate [Cd₂Br₆]^2- cadmium-bromide clusters. These clusters display crystallographic inversion symmetry forming two edge-shared tetrahedra and serve as agents that direct the structure in the formation of supramolecular assemblies. In mononuclear complex 4, the coordination geometry around the Hg²⁺ ion is distorted tetrahedral and comprises two chloride ligands and two N-atom donors from the phpy2NS ligand, viz. one pyridine N atom and the other from triazole. In the crystal packing, all four compounds exhibit weak intermolecular interactions, which facilitate the formation of three-dimensional architectures. Along with the noncovalent interactions, the structural diversity in the complexes can be attributed to the metal centre and to the coordination geometry, as well as to its ionic or neutral character.

Recent Research Trends on Bismuth Compounds in Cancer Chemoand Radiotherapy

Background:

Application of coordination chemistry in nanotechnology is a rapidly developing research field in medicine. Bismuth complexes have been widely used in biomedicine with satisfactory therapeutic effects, mostly in Helicobacter pylori eradication, but also as potential antimicrobial and anti-leishmanial agents. Additionally, in recent years, application of bismuth-based compounds as potent anticancer drugs has been studied extensively.

Methods:

Search for data connected with recent trends on bismuth compounds in cancer chemo- and radiotherapy was carried out using web-based literature searching tools such as ScienceDirect, Springer, Royal Society of Chemistry, American Chemical Society and Wiley. Pertinent literature is covered up to 2016.

Results:

In this review, based on 213 papers, we highlighted a number of current problems connected with: (i) characterization of bismuth complexes with selected thiosemicarbazone, hydrazone, and dithiocarbamate classes of ligands as potential chemotherapeutics. Literature results derived from 50 papers show that almost all bismuth compounds inhibit growth and proliferation of breast, colon, ovarian, lung, and other tumours; (ii) pioneering research on application of bismuth-based nanoparticles and nanodots for radiosensitization. Results show great promise for improvement in therapeutic efficacy of ionizing radiation in advanced radiotherapy (described in 36 papers); and (iii) research challenges in using bismuth radionuclides in targeted radioimmunotherapy, connected with choice of adequate radionuclide, targeting vector, proper bifunctional ligand and problems with 213Bi recoil daughters toxicity (derived from 92 papers).

Conclusion:

This review presents recent research trends on bismuth compounds in cancer chemo- and radiotherapy, suggesting directions for future research.

Synthesis, screening and biological activity of potent thiosemicarbazone compounds as a tyrosinase inhibitor

Inhibitors are designed based on coordination chemistry and catalytic circle of the tyrosinase, coordination atoms binds to copper and blocks enzyme activity, indicated that thiosemicarbazone species possess good potential as tyrosinase inhibitors.

Synthesis of 2-acetylpyridine-N-substituted thiosemicarbazonates of copper(ii) with high antimicrobial activity against methicillin resistant S. aureus, K. pneumoniae 1 and C. albicans

The basic interest in the present study pertains to developing metal based antimicrobial agents, as several microorganisms have built resistance to the conventional drugs.

Crystal structure and Hirshfeld surface analysis of (E)-1-[(4,7-di-methyl-quinolin-2-yl)methyl-idene]semicarbazide dihydrate

In the title compound, C13H14N4O·2H2O, the organic mol-ecule is almost planar. In the crystal, the mol-ecules are linked by O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonds, forming a two-dimensional network parallel to (10). Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H⋯H (55.4%), H⋯O/O⋯H (14.8%), H⋯C/C⋯H (11.7%) and H⋯N/N⋯H (8.3%) inter-actions.