Benzylidene Ring Research Articles

Synthesis and pancreatic lipase inhibition activity evaluation ofaurone derivatives with substituents on benzylidene ring

Pancreatic lipase is an essential enzyme for the digestion and absorption of dietary fat. Inhibiting this enzyme is one of the strategies in tackling obesity. To date, orlistat is the only Food and Drug Administration (FDA)-approved drug for obesity treatment via this mechanism. Therefore, there has been a growing interest in exploring novel compounds with natural structural frameworks that can give similar activity with fewer side effects. In this study, we describe the synthesis and pancreatic lipase inhibitory activity evaluation of 10 aurone derivatives with different substituents on the benzylidene ring. Aurone derivatives were synthesised through aldol condensation of benzofuranone and corresponding benzaldehyde derivatives with medium to good yields (45-73%). Pancreatic lipase inhibitory activities of synthesized compounds were determined by UV-Vis spectroscopy with quercetin and orlistat as references. Three aurones were found to have higher I% than quercetin at the same concentration (50 μg/ml). Compound 5c (2-(5’bromo-2’-hydroxybenzylidene)benzofuran-3(2H)-one) exhibited the greatest activity (I%=60.95%), better than quercetin (I%=27.20%) at the concentration of 50 μg/ml

Nitro-benzylideneoxymorphone, a bifunctional mu and delta opioid receptor ligand with high mu opioid receptor efficacy.

Introduction: There is a major societal need for analgesics with less tolerance, dependence, and abuse liability. Preclinical rodent studies suggest that bifunctional ligands with both mu (MOPr) and delta (DOPr) opioid peptide receptor activity may produce analgesia with reduced tolerance and other side effects. This study explores the structure-activity relationships (SAR) of our previously reported MOPr/DOPr lead, benzylideneoxymorphone (BOM) with C7-methylene-substituted analogs. Methods: Analogs were synthesized and tested in vitro for opioid receptor binding and efficacy. One compound, nitro-BOM (NBOM, 12) was evaluated for antinociceptive effects in the warm water tail withdrawal assay in C57BL/6 mice. Acute and chronic antinociception was determined, as was toxicologic effects on chronic administration. Molecular modeling experiments were performed using the Site Identification by Ligand Competitive Saturation (SILCS) method. Results: NBOM was found to be a potent MOPr agonist/DOPr partial agonist that produces high-efficacy antinociception. Antinociceptive tolerance was observed, as was weight loss; this toxicity was only observed with NBOM and not with BOM. Modeling supports the hypothesis that the increased MOPr efficacy of NBOM is due to the substituted benzylidene ring occupying a nonpolar region within the MOPr agonist state. Discussion: Though antinociceptive tolerance and non-specific toxicity was observed on repeated administration, NBOM provides an important new tool for understanding MOPr/DOPr pharmacology.

Syntheses, crystal structures, Hirshfeld surface analyses and energy frameworks of two 4-amino-anti-pyrine Schiff base compounds: (E)-4-{[4-(di-ethyl-amino)-benzyl-idene]amino}-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one and (E)-4-[(4-fluoro-benzyl-idene)amino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one.

The title Schiff base compounds, C22H26N4O (I) and C18H16FN3O (II), were each synthesized by a single-step condensation reaction. The substituted benzyl-idene ring is inclined to the pyrazole ring mean planes by 22.92 (7)° in I and 12.70 (9)° in II. The phenyl ring of the 4-amino-anti-pyrine unit is inclined to the pyrazole ring mean plane by 54.87 (7)° in I and by 60.44 (8)° in II. In the crystal of I, the mol-ecules are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions to form layers lying parallel to (001). In the crystal of II, the mol-ecules are linked by C-H⋯O and C-H⋯F hydrogen bonds and C-H⋯π inter-actions, thereby forming layers lying parallel to (010). Hirshfeld surface analysis was employed to further qu-antify the inter-atomic inter-actions in the crystals of both compounds.

Synthesis, in vitro α-glucosidase inhibitory activities, and molecular dynamic simulations of novel 4-hydroxyquinolinone-hydrazones as potential antidiabetic agents

In the present study, new structural variants of 4-hydroxyquinolinone-hydrazones were designed and synthesized. The structure elucidation of the synthetic derivatives 6a–o was carried out using different spectroscopic techniques including FTIR, 1H-NMR, 13C-NMR, and elemental analysis, and their α-glucosidase inhibitory activity was also determined. The synthetic molecules 6a–o exhibited good α-glucosidase inhibition with IC50 values ranging between 93.5 ± 0.6 to 575.6 ± 0.4 µM as compared to the standard acarbose (IC50 = 752.0 ± 2.0 µM). Structure–activity relationships of this series were established which is mainly based on the position and nature of the substituent on the benzylidene ring. A kinetic study of the active compounds 6l and 6m as the most potent derivatives were also carried out to confirm the mode of inhibition. The binding interactions of the most active compounds within the active site of the enzyme were determined by molecular docking and molecular dynamic simulations.

Microwave-assisted synthesis of 4,6-dihydroxyaurone derivatives

In this study, the authors described the evaluation of microwave-assisted reaction conditions for the synthesis of 4,6-dihydroxyaurone derivatives, including synthesis of 2’,4’,6’-trihydroxychloroacetophenone (50 W, 65°C and 30 min); synthesis of 4,6-dihydroxybenzofuran-3(2H)-one (50 W, 60°C and 5 min), and synthesis of 4,6-dihydroxyaurone (50 W, 80°C and 20-40 min). The optimum procedure was applied to prepare 4,6-dihydroxyaurone derivatives with different substituents on the benzylidene ring.

Substituent Effects on the Ultraviolet Absorption Properties of 2,4-Dihydroxy Dibenzophenone

Substituent effects on the ultraviolet absorption properties of 2,4-dihydroxy dibenzophenone were investigated experimentally. Nine compounds of 2,4-dihydroxy dibenzophenone with different substituents were prepared by a solvent-free reaction of benzoyl chloride. The maximum absorption wavelength (λmax) of these samples was measured, and their UV resistance properties in cotton fabric as well as in polyester were determined. The results show that the λmax is dependent on the substituents at the benzylidene ring, and both electron donating substituents and electron withdrawing substituents cause a bathochromic shift. The UV resistance of fabric increases with the increase in compound concentration. The dyeing rate of each compound on polyester was higher than that of cotton. On cotton fabric, the dyeing rate of 2,4-dihydroxybenzophenone was the highest, 77.8%. On polyester, that of 2,4-dihydroxy-4'-ethyl dibenzophenone was the highest, 84.1%. The study provides new insights into the effect of substituents on the properties of 2,4-dihydroxy dibenzophenone that are related to the whitening of cotton and polyester materials.

Computational study of nitro-benzylidene phenazine as dengue virus-2 NS2B-NS3 protease inhibitor.

According to the World Health Organisation (WHO), as of week 23 of 2022, there were more than 1,311 cases of dengue in Malaysia, with 13 deaths reported. Furthermore, there was an increase of 65.7% during the same period in 2021. Despite the increase in cumulative dengue incidence, there is no effective antiviral drug available for dengue treatment. This work aimed to evaluate several nitro-benzylidene phenazine compounds, especially those that contain 4-hydroxy-3,5-bis((2-(4-nitrophenyl)hydrazinylidene)-methyl)benzoate through pharmacophore queries selection method as potential dengue virus 2 (DENV2) NS2B-NS3 protease inhibitors. Herein, molecular docking was employed to correlate the energies of selected hits' free binding and their binding affinities. Pan assay interference compounds (PAINS) filter was also adopted to identify and assess the drug-likeness, toxicity, mutagenicity potentials, and pharmacokinetic profiles to select hit compounds that can be considered as lead DENV2 NS2B-NS3 protease inhibitors. Molecular dynamics assessment of two nitro-benzylidene phenazine derivatives bearing dinitro and hydroxy groups at the benzylidene ring showed their stability at the main binding pocket of DENV2 protease, where their MM-PBSA binding energies were between -22.53 and -17.01kcal/mol. This work reports those two nitro-benzylidene phenazine derivatives as hits with 52-55% efficiency as antiviral candidates. Therefore, further optimisation is required to minimise the lead compounds' toxicity and mutagenicity.

Predicting initiation rates of Hoveyda-Grubbs complexes containing an electron-withdrawing group in four possible positions of the benzylidene ring

The initiation rate of ruthenium metathesis catalysts is one of their most important characteristics from the applicational point of view due to the fact, that initiation is often the rate-limiting step of the entire catalytic cycle. Such initiation rate can be adjusted by introducing various modifications to the commonly used Grubbs-like and Hoveyda-Grubbs-like catalysts. Using a DFT approach, we predicted the initiation rates of the 2nd generation Hoveyda-Grubbs catalyst analogues substituted with electron-withdrawing –NO, –NO2, and –SO2C4F9 groups in all positions of the phenyl ring in the benzylidene part. We show that some of the modifications should result in very fast-initiating catalysts. In particular, the –SO2C4F9-substitued derivatives are predicted to be the fastest-initiating in the series. We also found correlations between the selected computed parameters such as the Gibbs free energy barrier for initiation and ruthenium-oxygen bond strengths which, combined with distortion energy analysis, allowed us to provide an explanation of the main driving force behind fast initiation.

Predicting Initiation Rates of Hoveyda-Grubbs Complexes Containing an Electron-Withdrawing Group in Four Possible Positions of the Benzylidene Ring

Predicting Initiation Rates of Hoveyda-Grubbs Complexes Containing an Electron-Withdrawing Group in Four Possible Positions of the Benzylidene Ring

Exploiting diol reactivity for the access to unprecedented low molecular weight curdlan sulfate polysaccharides

Curdlan is a bacterial sourced polysaccharide, consisting of a linear backbone of β-1 → 3-linked glucose (Glc) units. The high interest in pharmaceutical applications of curdlan and derivatives thereof is fueling the study of multi-step sequences for regioselective modifications of its structure. Here we have developed semi-synthetic sequences based on a regioselective protection-sulfation-deprotection approach, allowing the access to some, new, low molecular weight curdlan polysaccharide derivatives with unprecedented sulfation patterns. Three different semi-synthetic schemes were investigated, all relying upon the installation of a cyclic benzylidene protecting group on Glc O-4,6-diols, followed by either direct sulfation and deprotection, or some additional steps – including a hydrolytic or oxidative cleavage of the benzylidene rings – prior to sulfation and deprotection. The six obtained polysaccharides were subjected to a detailed structural characterization by 2D-NMR analysis, revealing that some of them showed the majority of Glc units along the polymeric backbone decorated by unprecedented sulfation motifs.

Disentangling Chromophore States in a Reversibly Switchable Green Fluorescent Protein: Mechanistic Insights from NMR Spectroscopy.

The photophysical properties of fluorescent proteins, including phototransformable variants used in advanced microscopy applications, are influenced by the environmental conditions in which they are expressed and used. Rational design of improved fluorescent protein markers requires a better understanding of these environmental effects. We demonstrate here that solution NMR spectroscopy can detect subtle changes in the chemical structure, conformation, and dynamics of the photoactive chromophore moiety with atomic resolution, providing such mechanistic information. Studying rsFolder, a reversibly switchable green fluorescent protein, we have identified four distinct configurations of its p-HBI chromophore, corresponding to the cis and trans isomers, with each one either protonated (neutral) or deprotonated (anionic) at the benzylidene ring. The relative populations and interconversion kinetics of these chromophore species depend on sample pH and buffer composition that alter in a complex way the strength of H-bonds that contribute in stabilizing the chromophore within the protein scaffold. We show in particular the important role of histidine-149 in stabilizing the neutral trans chromophore at intermediate pH values, leading to ground-state cis-trans isomerization with a peculiar pH dependence. We discuss the potential implications of our findings on the pH dependence of the photoswitching contrast, a critical parameter in nanoscopy applications.

C3 amino-substituted chalcone derivative with selective adenosine rA1 receptor affinity in the micromolar range.

To identify novel adenosine receptor (AR) ligands based on the chalcone scaffold, herein the synthesis, characterization and in vitro and in silico evaluation of 33 chalcones (15–36 and 37–41) and structurally related compounds (42–47) are reported. These compounds were characterized by radioligand binding and GTP shift assays to determine the degree and type of binding affinity, respectively, against rat (r) A1 and A2A ARs. The chalcone derivatives 24, 29, 37 and 38 possessed selective A1 affinity below 10 µM, and thus, are the most active compounds of the present series; compound 38 was the most potent selective A1 AR antagonist (Ki (r) = 1.6 µM). The structure–affinity relationships (SAR) revealed that the NH2-group at position C3 of ring A of the chalcone scaffold played a key role in affinity, and also, the Br-atom at position C3′ on benzylidene ring B. Upon in vitro and in silico evaluation, the novel C3 amino-substituted chalcone derivative 38—that contains an α,ß-unsaturated carbonyl system and easily allows structural modification—may possibly be a synthon in future drug discovery.Graphic abstractC3 amino-substituted chalcone derivative (38) with C3′ Br substitution on benzylidene ring B possesses selective adenosine rA1 receptor affinity in micromolar range.Electronic supplementary materialThe online version of this article (10.1007/s11696-020-01414-9) contains supplementary material, which is available to authorized users.

Butylated hydroxy benzylidene ring: an important moiety for antioxidant synergism of semicarbazones

The compounds having two or more antioxidant functions in their structure exhibit antioxidant synergism that generally increase the antioxidant activity of these compounds. In this study, two series of semicarbazone (7a–j and 7a′–j′) bearing butylated ortho and para hydroxy benzylidene ring were prepared for the investigation of antioxidant synergism. This study found that intramolecular hydrogen bond can form in semicarbazones due to the inappropriate position of hydroxyl group on benzylidene ring, which adversely affects the antioxidant synergism. As consequence, butylated para hydroxyl benzylidene phenyl semicarbazone (7a) (IC50 12.27 µM) showed ~ 4.3 times and ~ 2.7 times better antioxidant activity than compounds 7a′ (IC50 53.30 µM) and BHT (IC50 32.63 µM), respectively, in DPPH assay. In addition, based on the solubility in trimethylolpropane trioleate (TMPTO) as synthetic base oil and obtained IC50 results, oxidation stability of synthesized compounds was also evaluated by two kinds of differential scanning calorimeter (DSC) test, namely temperature ramping DSC and programmed temperature DSC. Thermogravimetric analysis is also performed for the thermal stability assessment. TMPTO incorporated with 0.25 mass% of 7c and 7e were found better oxidative (around 2 times) and thermal resistance than BHT. This DSC results showed another important aspect of semicarbazones that proper modification of semicarbazones can be used in the synthetic lubricant oil as a potential antioxidant. Thus, the results of this study are promising which can be taken under consideration to design and prepare more efficient multipotent semicarbazones.

Structural comparison of five new halogenated dihydroquinoline-4(1H)-ones

Compounds with dihydroquinoline-4(1H)-one nuclei have been reported in the literature for being important in the development of medicines due to their broad spectrum of activities. In this way, the structural knowledge of this class becomes relevant for obtaining new materials with desired biological properties. This study presents the structural elucidation of five halogenated dihydroquinolines, as well as the discussion about the effect on the molecular conformation of the type and position of halogen atom on aromatic rings. Compounds I and IV differ in halogen substitution on 2-phenyl ring, while compounds III and V differ in halogen substitution on the benzylidene ring. Moreover, compound II has a para-substituted 2-phenyl ring in their molecular structure. The crystal packing of all five molecules is mainly ruled by C–H⋯O and C–H···halogen interactions that form dimers and chains. The shift in position and the kind of the halogen in ring C shows a starring role in the conformation of the studied compounds, and the packaging of these compounds is more susceptible to variations when the halogen position changes.

Antileishmanial activity evaluation of thiazolidine-2,4-dione against Leishmania infantum and Leishmania braziliensis.

Leishmaniasis is responsible for approximately 65,000 annual deaths. Despite the mortality data, drugs available for the treatment of patients are insufficient and have moderate therapeutic efficacy in addition to serious adverse effects, which makes the development of new drugs urgent. To achieve this goal, the integration of kinetic and DSF assays against parasitic validated targets, along with phenotypic assays, can help the identification and optimization of bioactive compounds. Pteridine reductase 1 (PTR1), a validated target in Leishmania sp., is responsible for the reduction of folate and biopterin to tetrahydrofolate and tetrahydrobiopterin, respectively, both of which are essential for cell growth. In addition to the in vitro evaluation of 16 thiazolidine-2,4-dione derivatives against Leishmania major PTR1 (LmPTR1), using the differential scanning fluorimetry (ThermoFluor®), phenotypic assays were employed to evaluate the compound effect over Leishmania braziliensis (MHOM/BR/75/M2903) and Leishmania infantum (MHOM/BR/74/PP75) promastigotes viability. The ThermoFluor® results show that thiazolidine-2,4-dione derivatives have micromolar affinity to the target and equivalent activity on Leishmania cells. 2b is the most potent compound against L. infantum (EC50 = 23.45 ± 4.54μM), whereas 2a is the most potent against L. braziliensis (EC50 = 44.16 ± 5.77μM). This result suggests that lipophilic substituents on either-meta and/or-para positions of the benzylidene ring increase the potency against L. infantum. On the other hand, compound 2c (CE50 = 49.22 ± 7.71μM) presented the highest selectivity index.

Synthesis, Anticancer, and Antibacterial Studies of Benzylidene Bearing 5-substituted and 3,5-disubstituted-2,4-Thiazolidinedione Derivatives

To develop novel compounds having potent anticancer and antibacterial activities. Several studies have proved that benzylidene analogues of clinical 2,4-TZDs, such as troglitazone and ciglitazone, have more potent antiproliferative activity than their parent compounds. Literature studies also revealed that the attachment of more heterocyclic rings, containing nitrogen on 5th position of 2,4-TZD, can enhance the antimicrobial activity. Hence, attachment of various moieties on the benzylidene ring may produce safe and effective compounds in the future. The objective of the present study was to synthesize a set of novel benzylidene ring containing 5- and 3-substituted-2,4-thiazolidinedione derivatives and evaluate them for their anticancer and antibacterial activity. The synthesized compounds were characterized by IR, NMR, mass, and elemental studies. The in vitro cytotoxicity studies were performed for human breast cancer (MCF-7) and human lung cancer (A549) cells and HepG2 cell-line and compared to standard drug doxorubicin by MTT assay. Antimicrobial activity of the synthesized 2,4-thiazolidinediones derivatives was carried out using the cup plate method with slight modification. The results obtained showed that TZ-5 and TZ-13 exhibited good antiproliferative activity against A549 cancer cell-line, whereas TZ-10 exhibited moderate antiproliferative activity against HepG2 cell-line when compared to standard drug doxorubicin. TZ-5 also exhibited reasonable activity against the MCF-7 cell-line with doxorubicin as standard. TZ-4, TZ-5, TZ-6, TZ-7, and TZ- 16 exhibited remarkable antibacterial activity against Gram positive and moderate activity against Gram negative bacteria with the standard drug ciprofloxacin. Attachment of heterocyclic rings containing nitrogen as the hetero atom improves the anticancer and antimicrobial potential. Attachment of electronegative elements like halogens can also enhance the antimicrobial activity. Further structure modifications may lead to the development of more potent 2,4-TZD leads that can be evaluated for further advanced studies.

SYNTHESIS, IN SILICO STUDIES AND EVALUATION OF ANTIBACTERIAL ACTIVITY OF 4-SUBSTITUTED BENZYLIDENE-2-(PHENOXYMETHYL) OXAZOL-5(4H)-ONES

Objective: Arylidene-1, 3-oxazol-5-ones represent potential antibacterial agents. In the present work, a series of 4-substituted benzylidene-2- (phenoxymethyl) oxazol-5(4H)-ones were synthesized and screened for antibacterial activity against Gram-negative bacteria Escherichia coli. To explore plausible mechanisms, synthesized compounds were docked with DNA-Gyrase enzyme.
 Methods: All the reactants, phenoxy acetyl chloride, acetic anhydride, sodium acetate, substituted aromatic aldehydes, and glycine were triturated in a mortar by mechanical stirring. The antibacterial potentiality of the compounds was screened against E. coli using the disk diffusion method and the activity was recorded as a zone of inhibition.
 Results: Compound 2d, possessing 3, 4, 5-trimethoxy functionality on benzylidene ring exhibited the highest activity with 19 mm of the zone of inhibition which might be due to its higher interactions with DNA-Gyrase enzyme (ΔG-8.41 kcal/mol). Compounds 2a, 2b, and 2c exhibited moderate activity in the antimicrobial assay as well as in docking study indicating the positive contribution of substitution on benzylidene ring.
 Conclusion: A series of 4-substituted benzylidene-2-(phenoxymethyl) oxazol-5(4H)-ones were synthesized and evaluated for antibacterial activity. Compounds 2a, 2b, and 2c displayed moderate activity whereas 2d showed maximum zone of inhibition (19 mm). The good activity of these derivatives presumed to be due to the conformational flexibility of phenoxy methylene moiety which can be well accommodated in the target binding site.

Crystal structure and Hirshfeld surface analysis of two (E)-N'-(para-substituted benzyl-idene) 4-chloro-benzene-sulfono-hydrazides.

Two (E)-N'-(p-substituted benzyl-idene)-4-chloro-benzene-sulfono-hydrazides, namely, (E)-4-chloro-N'-(4-chloro-benzyl-idene)benzene-sulfono-hydrazide, C13H10Cl2N2O2S, (I), and (E)-4-chloro-N'-(4-nitro-benzyl-idene)benzene-sulfono-hydrazide, C13H10ClN3O4S, (II), have been synthesized, characterized and their crystal structures studied to explore the effect of the nature of substituents on the structural parameters. Compound (II) crystallized with two independent mol-ecules [(IIA) and IIB)] in the asymmetric unit. In both compounds, the configuration around the C=N bond is E. The mol-ecules are twisted at the S atom with C-S-N-N torsion angles of -62.4 (2)° in (I), and -46.8 (2)° and 56.8 (2)° in the mol-ecules A and B of (II). The 4-chloro-phenyl-sulfonyl and 4-substituted benzyl-idene rings form dihedral angles of 81.0 (1)° in (I), 75.9 (1)° in (IIA) and 73.4 (1)° in (IIB). In the crystal of (I), mol-ecules are linked via pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 2(8) ring motif. The dimers are linked by C-Cl⋯π inter-actions, forming a three-dimensional structure. In the crystal of (II), mol-ecules are linked by C-H⋯π inter-actions and N-H⋯O hydrogen bonds, forming -A-B-A-B- chains along the c-axis direction. The chains are linked via C-H⋯O and C-H⋯π inter-actions, forming layers parallel to the bc plane. Two-dimensional fingerprint plots show that the most significant contacts contributing to the Hirshfeld surface for (I) are H⋯H contacts (26.6%), followed by Cl⋯H/H⋯Cl (21.3%), O⋯H/H⋯O (15.5%) and Cl⋯C/C⋯Cl (10.7%), while for (II) the O⋯H/H⋯O contacts are dominant, with a contribution of 34.8%, followed by H⋯H (15.2%), C⋯H/H⋯C (14.0%) and Cl⋯H/H⋯Cl (10.0%) contacts.

SYNTHESIS, SPECTRAL, AND PHARMACOLOGICAL EVALUATION OF 3 AND 5 SUBSTITUTED 2,4-THIAZOLIDINEDIONE DERIVATIVES

Background: 2,4-Thiazolidinedione derivatives was launched as antidiabetics in 90’s. Later the derivatives of 2,4-thiazolidinedione were banned due to hepatotoxicity. To the date, much research has been directed toward the synthesis and novel uses of 2,4-thiazolidinedione compounds.Aim: The aim of the present study is to synthesize a set of 3,5-disudstituted-2,4-thiazolidinediones as antimicrobial. These compounds were evaluated for their antimicrobial activity.Method: First, the 2,4-thiazolidinedione was substituted at the position of 3 using sodium hydroxide and ethanol and then substituted at the position of 5 in the presence of piperdine by the Knoevenagel condensation method. The structures of the compounds were established on the basis of infrared and nuclear magnetic resonance spectral studies.Result: 3,5-disubstituted-5-benzylidine-2,4-thiazolidinediones derivative was synthesized using benzyl halides and aromatic aldehydes. The results obtained showed that TZ-1 exhibited good activity against Bacillus subtilis while no activity against Escherichia coli.Conclusion: Attachment of more heterocyclic rings containing Nitrogen on the 3rd position of 2,4-thiazolidinedione can enhance the antimicrobial activity. Addition of more lipophilic agents may increase the bioavailability and efficacy of the drug. Long alkyl chains on the benzylidene ring can also increase the lipophilic character, and further attachment of these kind of agents on benzylidene chain may produce safe and effective compounds in future.

Crystal structures and the Hirshfeld surface analysis of (E)-4-nitro-N'-(o-chloro, o- and p-methyl-benzyl-idene)benzene-sulfono-hydrazides.

The crystal structures of (E)-N'-(2-chloro-benzyl-idene)-4-nitro-benzene-sulfono-hydrazide, C13H10ClN3O4S (I), (E)-N'-(2-methyl-benzyl-idene)-4-nitro-benzene-sulfono-hydrazide, C14H13N3O4S (II), and (E)-N'-(4-methyl-benzyl-idene)-4-nitro-benzene-sulfono-hydrazide monohydrate, C14H13N3O4S·H2O (III), have been synthesized, characterized and their crystal structures determined to study the effects of the nature and sites of substitutions on the structural parameters and the hydrogen-bonding inter-actions. All three compounds crystallize in the monoclinic crystal system, with space group P21 for (I) and P21/c for (II) and (III). Compound (III) crystallizes as a monohydrate. All three compounds adopt an E configuration around the C=N bond. The mol-ecules are bent at the S atom with C-S-N-N torsion angles of -59.0 (3), 58.0 (2) and -70.2 (1)° in (I), (II) and (III), respectively. The sulfono-hydrazide parts are also non-linear, as is evident from the S-N-N-C torsional angles of 159.3 (3), -164.2 (1) and 152.3 (1)° in (I), (II) and (III), respectively, while the hydrazide parts are almost planar with the N-N=C-C torsion angles being -179.1 (3)° in (I), 176.7 (2)° in (II) and 175.0 (2)° in (III). The 4-nitro-substituted phenyl-sulfonyl and 2/4-substituted benzyl-idene rings are inclined to each other by 81.1 (1)° in (I), 81.4 (1)° in (II) and 74.4 (1)° in (III). The compounds show differences in hydrogen-bonding inter-actions. In the crystal of (I), mol-ecules are linked via N-H⋯O hydrogen bonds, forming C(4) chains along the a-axis direction that are inter-connected by weak C-H⋯O hydrogen bonds, generating layers parallel to the ac plane. In the crystal of (II), the amino H atom shows bifurcated N-H⋯O(O) hydrogen bonding with both O atoms of the nitro group generating C(9) chains along the b-axis direction. The chains are linked by weak C-H⋯O hydrogen bonds, forming a three-dimensional framework. In the crystal of (III), mol-ecules are linked by Ow-H⋯O, N-H⋯Ow and C-H⋯O hydrogen bonds, forming layers lying parallel to the bc plane. The fingerprint plots generated for the three compounds show that for (I) and (II) the O⋯H/H⋯O contacts make the largest contributions, while for the para-substituted compound (III), H⋯H contacts are the major contributors to the Hirshfeld surfaces.