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Although it is known that the first case of cancer was recorded in ancient Egypt around 1600 BC, it was not until 1917 during the First World War and the development of mustard gas that chemotherapy against cancer became relevant; however, its properties were not recognised until 1946 to later be used in patients. In this sense, the use of metallopharmaceuticals in cancer therapy was extensively explored until the 1960s with the discovery of cisplatin and its anticancer activity. From that date to the present, the search for more effective, more selective metallodrugs with fewer side effects has been an area of continuous exploration. Efforts have led to considering a wide variety of metals from the periodic table, mainly from the d-block, as well as a wide variety of organic ligands, preferably with proven biological activity. In this sense, various research groups have found an ideal binder in Schiff bases, since their raw materials are easily accessible, their synthesis conditions are friendly and their denticity can be manipulated. Therefore, in this review, we have explored the anticancer and antitumor activity reported in the literature for coordination complexes of d-block metals coordinated with tridentate Schiff bases (O N O and O N N) derived from salicylaldehyde. For this work, we have used the main scientific databases CCDC® and SciFinder®.

This work presents three scientific contributions: the new metal organic framework (UV-012) crystal structure, the evaluation of this new material for dye adsorption and a new mechanism that explains the excellent and selective anionic dye adsorption by this material. UV-012 was synthesized by a solvothermal method and characterized by single crystal and powder XRD, scanning electron microscopy (SEM) and FT-IR. Methyl orange (MO) adsorption experiments in water were completed, obtaining the maximum adsorption capacity (1410 mg g−1) determined by Langmuir's mathematical model. The value obtained is one of the highest reported to date for a MOF or a coordination polymer; this exceptional performance is attributed to the MOF–dye electrostatic interaction, which is associated with bpp linkers in the MOF structure. The adsorption kinetics is described by a pseudo-second-order model. The pH effect was studied, which indicated that the adsorption capacity decreases proportionally when the pH increases. UV-012 presents high potential to adsorb other anionic dyes such as Congo red or indigo carmine; however, its cationic dye adsorption performance (methylene blue) was not significant, which indicates selectivity toward anionic dyes. The most important conclusion of this work is: MOFs constructed from pyridinic linkers will present high adsorption capacity in the removal of anionic dyes, due to the strong electrostatic interaction between this type of linker and the negative charge of the dye. To the best of our knowledge, this conclusion has not been published previously.

Six coordination complexes: {[H2NMe2][Co(CHO2)3]}n (1), [Co(bpy)(CHO2)2]n (2), [Cu(dmf)(CHO2)2]2 (3), {[H2NMe2][Cu(CHO2)3]}n (4), [H2NMe2]4[Fe4O2(dmf)4(SO4)6] (5) and [Co3(bpy)(SO4)3]n (6) have been efficaciously synthesized using solvothermal techniques and slow evaporation. Two compounds (5 and 6) containing the sulfate anion (SO42−) with iron (III) and cobalt (II) had never been described in the Cambridge Structural Database. In all complexes, the transition metal is hexacoordinated with a distorted octahedral geometry and displays a three-dimensional supramolecular architecture through hydrogen bonding interactions [N H⋯O]. Formate (CHO2−) and sulfate (SO42−) anions were very important to the assembly of the three-dimensional MOFs and can be regarded as the template for all structures. All metal-organic complexes were identified by single-crystal X-ray diffraction, elemental composition and Fourier-transform infrared spectroscopy. In this paper, we propose the PM7 and ONIOM calculations as two effective methods in the determination of hydrogen storage. The weight percentage (wt %) of the hydrogen stored in the small cavities of the PCPs studied were: (1) 1.03 wt %, (4) 1.01 wt %, (6) 0.28 wt %.

In the last 20 years, N-Heterocyclic Carbene (NHC) ligands have been ubiquitous in biological and medicinal chemistry. Part of their success lies in the tremendous number of topologies that can be synthesized and thus finely tuned that have been described so far. This is particularly true in the case of those derivatives, including fluorine or fluorinated fragments on their NHC moieties, gaining much attention due to their enhanced biological properties and turning them into excellent candidates for the development of novel metallodrugs. Thus, this review summarizes the development that fluorinated-NHC transition metal complexes have had and their impact on cancer treatment.

Seven new complexes obtained of hydrated lanthanide(III) nitrates with 2,6-bis(5-methyl-benzimidazol-2-yl)pyridine (bmbp) having the formula [LnIII(bmbp)(NO3)2]NO3 n-H2O (where LnIII = LaIII, NdIII, SmIII, EuIII, GdIII, TbIII, DyIII) have been prepared and characterized by ultraviolet–visible and infrared absorption spectroscopies, molar conductivity and elemental composition. The emission spectra of the all complexes have also been analyzed; it has been detected that all complexes revealed the luminescence of bmbp. Samarium and europium complexes also displayed the corresponding lanthanides luminescence. The metal ion is coordinated to seven atoms resultant to three nitrogens of bmbp and to two oxygens for each of the bidentate nitrate groups. Density functional theory calculations were utilized to designate the singlet and triplet excited state energy levels of bmbp.

Three lanthanide complexes, [H2NMe2]3[Ln(III)(2,6-pyridinedicarboxylate)3] (Ln = Sm, Eu, Tb) have been successfully synthesized using a solvothermal method in the presence of a base and they were prepared from inexpensive and readily available reactants. Infrared, ultraviolet–visible absorption spectroscopies, elemental analyses and thermogravimetric analysis were employed for the characterization. Crystals suitable for X-ray diffraction were isolated in good yields by a simple filtration, their crystal structures were analyzed; the samarium structure has orthorhombic symmetry with space group Pbcn, exhibiting three-dimensional supramolecular architecture through hydrogen bonding interactions. The metal center is coordinated to nine atoms corresponding to three pyridine-2,6-dicarboxylic acid molecules. These compounds are thermally stable up to 270 °C.

Fourteen new complexes were obtained from Ln(III)(NO3)3∙n-H2O and the chromophores 2-(1H-benzo[d]imidazol-2-yl)-phenol (Bzp1) or 2-(5-methyl-1H-benzo[d]imidazol-2-yl)-phenol (Bzp2). The complete characterization allowed us to assign unequivocally the structures of all the complexes. The techniques used for this purpose were Ultraviolet-Visible (UV-Vis) and Fourier-Transform Infrared (FT-IR) spectroscopies, High-Resolution Mass Spectrometry (HRMS), Magnetic Susceptibility (MS), Elemental Analysis (EA) and Molar Conductivity (MC). HRMS allowed us to find the molecular ion and its isotopic pattern. The FT-IR spectral data suggested that benzimidazolyl-phenol ligands coordinate with Ln(III) ions through iminic nitrogen and phenolic oxygen. Thermogravimetric Analysis (TGA) studies of NdBzp1 and GdBzp2 complexes indicate the presence of lattice water along with three nitrates and two benzimidazolyl-phenol ligands; the thermal decomposition was consistent with the minimal formula suggested by EA. The coordination type of the benzimidazolyl-phenol ligands, the geometry and the structural organization of these coordination complexes have been interpreted by Density Functional Theory (DFT) calculations, and they coincided with the physicochemical data suggesting a coordination number eight for the Ln(III) ions. The cytotoxicity of the chromophores and their coordination complexes was tested against a cancer cell line (HeLa), as compared with structure/support cells (NIH-3T3) and defense cells (J774A.1), revealing that three coordination complexes showed moderate cytotoxicity against the cell lines studied.

Cancer can be defined as an irregular functioning of the cell cycle that results in a progressive loss of cell differentiation and uncontrolled cell growth. Moreover, despite countless research advances in prevention and therapy, cancer remains one of the leading causes of death worldwide. Besides surgery, radiotherapy and immunotherapy, chemotherapy is one of the most effective methods for cancer treatment. However, in many cases, commercial chemotherapeutic agents suffer of limited efficacy and serious side effects. In addition, major chemotherapy treatments often experience major hurdles, being multi-drug resistance (MDR) the biggest obstacle. Hence, major efforts have been devoted to the design of new anticancer drugs with enhanced efficacy against cancer cells with minimum side effects. Some of these commercial drugs include benzimidazole moieties on their structures, for instance abemaciclib, bendamustine, crenolanib, dovitinib, galeterone, glasdegib, liarozole, nocodazole, pracinostat, selumetinib, veliparib, among others. Thus, this manuscript reviews the in vitro anticancer and antitumor activity of the first-row transition metal compounds containing benzimidazole-based ligands on their structures. Factors such as the effect of ligand type, metal centre, molecular structure and geometry on biological activity were analysed; and the relevance of the first-row transition metals in the health area was discussed, including the different assays used in the determination of their cytotoxic activity. We hope that this review may serve to further stimulate and advance the design of novel metal coordination compounds including first-row transition metals and the use of benzimidazole ligands as an ideal combination to produce very active, yet selective potent metallodrugs.

Coordination complexes and metal–organic frameworks are compounds with unlimited applications in electrochemistry. Those based on Co, Ni, and Cu offer redox-active properties that can be an advantage for the electro-oxidation of short-chain alcohols in alkaline media. At the present, there is a crescent interest for its application in direct methanol fuel cells and a big effort is being carried out to improve the oxidation potentials obtained with these compounds before their practical uses as DMFCs anodes. Herein, we collected the recent advance on the use of coordination compounds (coordination complexes and Metal-Organic Frameworks) as modifiers for electrodes and their evaluation on methanol electro-oxidation in alkaline media. Fundamental aspects of the key role of coordination compounds in electro-oxidation, the fabrication of modified electrodes containing coordination compounds, and diverse examples of its use of methanol electro-oxidation will be discussed.

Herein we discuss the contribution of the NTB and BBP ligands in the coordination of trivalent lanthanide ions. There is a very versatile chemistry in these two N-donor ligands, which gives rise to great structural diversity. Ligands promote a wide range of molecular geometries and interactions, since the central atoms can reach different coordination numbers, going from heptacoordinated to decacoordinated. This review summarizes the synthesis procedures to obtain the free ligands, as well as a structural summary of their complexes with lanthanide(III) ions, together with an analysis of their luminescent properties. In the same way, this review focuses on the design of highly luminescent complexes and discusses the most relevant aspects of their sensitization, such as coordination number, molecular geometry, surrounding media, ligand functionalization, use of ancillary aromatic ligands, as well as the management of bidentate and monodentate coordinating anions. The luminescence of the complexes comes from the visible light emitting lanthanides and sensitization is promoted by ligands that act as an antenna. Obtaining an efficient emitter requires careful design of the coordination compound environment, including the use of suitable chromophores, which serve as an antenna and protect the coordination shell. The symmetry of the complex is also an important parameter, since the presence or absence of an inversion centre will influence the orbital mixing. Therefore, the coordination number is not the determining effect of luminescence, but an indicative of the symmetry of the compounds. We hope that from this review, weak points in the design of luminescent materials can be identified and a potential interest in the use of benzimidazole ligands as efficient sensitizers can be generated.

Nine new alkyl-oximes were obtained from 2-methyl-4(5)-nitro-1H-imidazole with 2-bromo-1-phenylethanone derivatives in a first step, as well as hydroxylamine hydrochloride and alkyl halide derivatives in a second step. Spectroscopic characterization mainly by NMR (nuclear magnetic resonance) allowed us to assign the 4-nitro and 5-nitro position isomers in the ethanone derivatives (3a-3c), it also allowed us to assign the geometric isomers (E/Z) in oximes (4a-4c) and alkyl-oximes (5a-5i). The HRMS (high-resolution mass spectrometry) allowed us to define the molecular ion (M + 1) with its isotopic pattern, complementing the unequivocal characterization of the nine compounds. Experimental and calculated FT-IR data (Fourier transform infrared spectroscopy) indicates that the symmetric and asymmetric bands of the nitro group do not change substantially when the ethanones become oximes. The position of the nitro group in the compounds, the optimized structures of minimum energy, as well as the geometric organization of the substituents in the isomers, have been interpreted by PBE0-D3/6–311++G(d,p) calculations and the results coincided with the spectroscopic data found experimentally.

Coordination cobalt and nickel complexes (1) and (2) were obtained serendipitously by the reaction of M(NO3)2·6H2O (M = Co and Ni) and methyliminodiacetic acid (H2L) in a mixture of solvents. The X-ray diffraction showed the unusual structures with Z′ = 4 of (1) and (2), showing the four monomers highly stabilized by hydrogen bonding interactions which corresponds to the tris-(aqua)-(N-methyliminodiacetato)-cobalt (II) and nickel (II) respectively. The Wiberg Bond Indices (WBIs) were computed on (1) and (2) to evaluate the stability of the hydrogen bonding interactions and showed a good correlation with the experimental X-ray diffraction data. Finally, the complex [Co (L)2 Na]n (3) corresponds to the heterometallic coordination framework which was obtained by addition of a second equiv. of methyliminodiacetic acid (H2L) in basic sodium hydroxide media. The oxidation of the cobalt atom in (3) was confirmed by the experimental coordination bond distances observed by XRD, which are in the range from 1.882 to 1.957 A.

The coordination behavior of the antiulcer drug cimetidine (cime) towards transition metal ions was investigated. The synthesis and characterization of [Cr(cime)2Cl2]Cl·3H2O, [Co(cime)Cl2]·5H2O, [Co(cime)3Cl]Cl·3H2O, [Ni(cime)Cl2(H2O)2]·H2O, [Cu(cime)Cl2]·2H2O, [Cu(cime)2Cl(H2O)]Cl·H2O, [Cu(cime)3Cl2]·3H2O, [Cu2(cime)Cl4], and [Zn(cime)Cl2]·1.5H2O are discussed, where cime acts as monodentate (imidazole N3) or bidentate ligand (N3 and S8). IR, UV-vis, EPR and NMR spectroscopies, mass spectrometry (FAB+), were employed for the characterization. In order to identify the most reactive areas of cimetidine, the electrostatic potential map of the ligand was calculated; also the structures of minimum energy of the coordination compounds were modeled using DFT (B3LYP/def2-TZVP) calculations.

The synthesis and structural study of 23 new bis-, tris-, tetra-(dithiazinan-2-yl)silanes and stannanes is reported. The compounds were obtained by reaction of 5-alkyl-[1,3,5]-dithiazinanes (alkyl ¼ Me, i Pr, t Bu) with t BuLi followed by addition of R 0 nSiCl4� n or R 0 nSnCl4� n (n ¼ 0e2, R 0 ¼ Me and Ph) in THF. Structures were determined by 1 H, 13 C, 29 Si or 119 Sn NMR, mass spectrometry and X-ray diffraction analyses. Conformation of compounds in the solid state is discussed. The silanyl and stannanyl groups are in equatorial position in bis and tris-dithiazinanyl compounds in solution. The X-ray diffraction of tetra-(Nisopropyl-dithiazinan-2-yl)stannane showed that the tin atom is bound to two dithiazinanyl groups by equatorial bonds and to other two by axial bonds. Atomic distances indicate sulfuresilicon and sulfuretin short contacts. NMR data, in particular 29 Si and 119 SN chemical shifts and 1 J( 13 C, 119 Sn) coupling constants, indicate the presence of weak S/Si and S/Sn interactions in the compounds. Ab-initio calculations were performed for (eq,eq,eq,eq), (ax,ax,ax,ax) and (eq,eq,ax,ax) conformers in order to find the most stable structures in tetra-(5-methyl-[1,3,5]-dithiazinan-2-yl)silane and tetra-(5-methyl-[1,3,5]-dithiazinan-2-yl) stannane.

A series of 2 - R 3 ′ E (E = Si or Sn; R′ = Me or Ph) derivatives of 5-R-[1,3,5]-dithiazinanes (R = Me, i Pr, t Bu) are reported, as well as some of their N–BH 3 adducts. Structures were determined by 29 Si, 119 Sn, 11 B, 13 C and 1 H NMR and X ray diffraction analyses. Minimum energy conformations were calculated by HF/6-31++G(d,p) and B3LYP/6-31++G(d,p) methods. Preferred conformations and steric and stereoelectronic interactions are analyzed. In the solid state the ring conformation is a chair with the N–R group in axial and the 2-substituents in equatorial position. The Si or Sn atoms linked to C-2 have short distances to the two sulfur atoms, interpreted as Si⋯S and Sn⋯S stabilizing contacts. The 119 Sn NMR chemical shifts and 1 J ( 13 C, 119 Sn) coupling constants evidenced weak S⋯Sn coordination bonds. Substitution reactions at C2 performed in N–BH 3 adducts of 2-lithium-5-methyl-[1,3,5]-dithiazinanes of anchored conformation proceed with retention of C2 configuration.

Two tridentate ligands derivated from ethanolamines and 2-hydroxyacetophenone and 2-hydroxybenzophenone were reacted with phenylboronic acid and naphthylboronic acid in different proportions to obtain compounds 7a, 8b and 9a which are [4.3.0] and [4.5.0] heterobicyclic systems. Compounds 7a, 8b and 9a were fully characterized and the structures of 7a and 8b have been analyzed by X-ray diffraction, where a series of parameters such as bond distances, bond angles, torsion angles, tetrahedral character at the boron atom, steric effects and deviation of the boron atom from the mean plane have been evaluated and comparated. DFT calculations, PBE/6-31G(d,p), were performed in order to evaluate steric effects and the stability of [4.3.0] and [4.5.0] heterobicyclic system.

A novel [(1,3-benzoxazol-2-yl)-(5-chloro-1,3-benzoxazol-2-yl)]amine (L) (1) compound was synthesized. The molecule has a nitrogen atom between 1,3-benzoxazol-2-yl and 5-chloro-1,3-benzoxazol-2-yl groups. For compound 1 there are twelve possible conformers and tautomers. Ab initio calculations were performed in order to investigate the more stable structures. Three crystals of compound 1 were obtained in different media, where compound 1 is associated by hydrogen bonding to H2O (1a), THF (1b), or o-aminophenol (1c). Their X-ray diffraction analyses are reported. The synthesis and structural study of the coordination compounds [Co(L)2(H2O)] (3) and [Ni(L)2(H2O)2] (4) are discussed.

A series of molybdenum(VI) complexes containing bidentate ligands: toluene-3,4-dithiol (1), 2-mercaptophenol (2), 2-aminothiophenol (3), ethane-1,2-dithiol (4), dithiooxamide (5) and 2-thiopheno-carboxamide (6) are reported. The hexacoordinated molybdenum tris-chelates compounds: tris-(toluene-3, 4-dithiolate)molybdenum(VI) (7), tris-(2-mercaptophenolate)molybdenum(VI) (8), tris-(2-aminothiophenolate)molybdenum(VI) (9), tris-(ethane-1,2-dithiolate)molybdenum(VI) (10), and the bis-chelates, which also contain coordinated oxo ligands: bis-(dithiooxamidate)dioxomolybdenum(VI) (11) and bis(2-thiopheno-carboxamide)dioxomolybdenum(VI) (12), were characterized by 1 H and

Nine new boronates, six of them chiral, with five-six-membered ring heterobicycles were prepared by reaction of the Schiff bases and phenyl boronic acid. The boronates were fully characterized by spectroscopic techniques, NMR 1H, 13C, 11B, Infrared spectroscopy, mass spectrometry and elemental analysis. The reaction showed high diasteroselectivity, only in the case of compound 4c, containing a methyl substituent in the aliphatic moiety, the induction is low giving a 2:1 mixture of two diatereoisomers. The results showed that the preferred stereochemistry in the heterocycles is that where all substituents in the five membered ring and the phenyl group attached to boron atom are on the same side.

The structure and reactivity of a series of new ethylaminedithiazinanes and bis-diethylaminedithiazinanes synthesized from formaldehyde, NaSH, and N,N-dimethyl-ethylene-diamine (1), N-methyl-ethylene-diamine (2), and N-ethyl-ethylene-diamine (3) are reported. Compound 1 afforded 2-([1,3,5]-dithiazinan-5-yl)-ethylene-N,N-dimethyl-amine (4). The reaction of 4 with dry CH2Cl2 gave N-{2-([1,3,5]dithiazinan-5-yl)-ethylene}-N-chloromethyl-N,N-dimethyl-ammonium chloride (5) in high yield, whereas in wet CH2Cl2 and DMSO provided a mixture of 5 with N-{2-([1,3,5]-dithiazinan-5-yl)-ethylene}-N,N-dimethyl-ammonium hydrochloride (6).bis-{2-([1,3,5]-Dithiazinan-5-yl)-ethylene-N-alkyl-amino}-methylene-disulfides (7) and (8) formed by two dithiazinanes linked through the chain (CH2)2NRCH2SSCH2NR(CH2)2- (7 R = methyl, 8 R = ethyl) reacted with CH2Cl2 giving after neutralization of the hydrolysis products the ethylaminedithiazinanes with different pendant N-groups [(CH2)2NMeH2+(9); (CH2)2NEtH2+ (10); (CH2)2NMeH (11); (CH2)2NEtH (12); (CH2)2NMeHBH3 (13) (CH2)2NEtHBH3 (14). (CH2)2NMe2BH3 (15), and (CH2)2NEtMeBH3.(16)]. The x-ray diffraction analyses of compounds 5, 6, 9, and 10 are reported. Variable temperature NMR experiments afforded the Δ G≠ of the ring interconversion of the six-membered heterocycles 6, 9, and 10. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:59–71, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20657

A series of boric esters, phosphites, phosphates, thiophosphates and selenophosphates derived from 2-(1,3,5-dithiazinan-5-yl)-ethanol ( 1 ), 2-(1,3,5-dithiazinan-5-yl)-1-methyl-ethanol ( 2) , and 2-(1,3,5-dithiazinan-5-yl)-1-phenylethanol ( 3 ) are reported. Enantiopure compounds (C3 symmetry) were prepared from 2 (−) and 3 (−) of (R) configuration. The new tripodal molecules were viscous liquids which were mainly characterized by 1 H, 13 C, 11 B, 31 P, 77 Se, NMR and VT-NMR experiments. BH 3 , BCl 3 , pyridine and PPh 3 O adducts of boric esters as well as the BH 3 adducts of phosphites were synthesized. The molecular geometries were calculated by HF/6-31G(d). The modeled molecules indicated a preferred ligand conformation which led to the formation of cavities. The complex NMR spectra of isomers were interpreted by comparison with the calculated geometries.

N-Benzyl-4-hydroxy-butyramide (1), 4-hydroxy-N-[(R)-1-phenyl-ethyl]-butyramide (2), and (R)-4-hydroxy-2-methyl-N-[(R)-1-phenyl-ethyl]-butyramide (3a) were used to prepare new diphenylboron and triphenyltinoxy compounds: diphenylborinic acid 3-benzylcarbamoyl-propyl ester (4), diphenylborinic acid 3-[(R)-1-phenyl-ethylcarbamoyl]-propyl ester (5) and diphenylborinic acid (R)-3-[(R)-1-phenyl-ethylcarbamoyl]-butyl ester (6), N-benzyl-4-triphenyltinoxy-butyramide (7), 4-triphenyltinoxy-N-[(R)-1-phenyl-ethyl]-butyramide (8), and (R)-4-triphenyltinoxy-2-methyl-N-[(R)-1-phenyl-ethyl]-butyramide (9). The X-ray diffraction analysis of a crystalline structure of the new γ-hydroxyamide 3a is reported, as well as that of the first example of a crystalline structure where a diphenylborinic ester forms a seven membered chelate, by a carbonyl coordination to boron (4). Structural studies of tin and boron esters were performed by NMR. The C O internal coordination to tin atoms, affording seven membered rings, was observed by 119Sn NMR experiments at low temperature.

In the title polymeric complex salt, {[Ni(C8H4NO2)(C10H8N2)(H2O)3](C8H4NO2)}n, the NiIIcation is coordinated by a 4-cyanobenzoate anion, two 4,4′-bipyridine ligands and three water molecules in a distorted N2O4octahedral geometry. The 4,4′-bipyridine ligands bridge the NiIIcations to form polymeric chains of the title complex cations, propagating along thec-axis direction. The dihedral angle between the pyridine rings of the 4,4′-bipyridine ligand is 24.9 (6)°. In the crystal, the uncoordinating 4-cyanobenzoate anions link with the complex cationsviaO—H...O hydrogen bonds into a three-dimensional supramolecular architecture. Weak C—H...O, C—H...N interactions and π–π stacking [centroid-to-centroid distances = 3.566 (4) and 3.885 (4) Å] are also observed in the crystal.

In the title compound, [Co2(C7H5O2)4(C10H8N2)4]·6C6H5COOH, the centrosymmetric cobalt dimer co-crystallizes with six molecules of benzoic acid. Each CoII atom is coordinated by four O atoms in a distorted square-planar arrangement while the N atoms are located in apical positions. The dihedral angles between the rings comprising each of the 4,4′-bipyridyl ligands are 25.2 (2) and 22.8 (2)°. In the crystal, the three-dimensional network is assembled by O—H...O and C—H...O hydrogen bonds.

Alkyl-4-tosyl-3-carboxymethyl-1,2,3,4-tetrahydroquinoxalin-2-ones were synthesized by means of a key step that consisted in a condensation reaction between o-phenylenediamine and maleic anhydride, followed by tosylation and final alkylation. The X-ray diffraction of 3- carboxymethyl-4-tosyl-1,2,3,4-tetrahydroquinoxalin-2-one benzyl ester (1e) and 1-benzyl-3- carboxymethyl-4-tosyl-1,2,3,4-tetrahydroquinoxalin-2-one benzyl ester (1f) is reported.