Ortho Derivatives Research Articles

An Alternative Method for the Selective Synthesis of Ortho-nitro Anilines Using Bismuth Nitrate Pentahydrate.

Nitroaromatic compounds are important scaffolds used for the syn-thesis of a variety of compounds, such as explosives, herbicides, dyes, perfumes and phar-maceuticals. Bismuth nitrate pentahydrate is a widely used reagent in organic synthesis; how-ever, its utility as a nitrating agent for anilines is underexplored. The aim of this work is to propose and find the proper reaction conditions of an alternative nitrating agent constituted by a mixture of bismuth nitrate / acetic anhydride in DCM with a series of substituted anilines under mild reflux. Several anilines having both activating and deactivating substituents in the ortho, meta and para positions were the substrate for the nitration reaction. Experimental conditions were performed in "one-pot" conditions before product purification. Bi(NO3)3•5H2O demonstrated to be effective and somehow regioselective when it came to the nitration of anilines in the ortho position. Although other products were also identified under these conditions, in most cases, the ortho derivative was the major or even the only product obtained with moderate to high yields in the range of 50% - 96%. Bi(NO3)3•5H2O is an efficient and safe nitrating agent since the use of concen-trated and corrosive acids like sulfuric and nitric is avoided; furthermore, bismuth nitrate is low-priced and no special care nor equipment is required.

Crystal packing of structurally similarand strong dimeric subunits of isomeric N/ -(1,3- benzothiazol-2-yl)nitrobenzenesulfonylhydrazides, influenced by the position of the nitro group

Detailed structural analyses, utilizing single crystal X-ray diffraction, Hirshfeld surface analyses, PIXEL and electrostatic potentials calculations, have been carried out on three isomeric N/-(1,3-benzothiazol-2-yl)nitrobenzenesulfonylhydrazides, Bt-NHNHSO2C6H4NO2-o, m and p. These compounds each crystallize from ethanol solution with two independent, but similar, amino tautomers, in the asymmetric units. For all three compounds, similar and dominant dimeric unsymmetric sub-structures are present in the solid state, linked prominently by pairs of N—H(hydrazinyl)···N(thiazolyl) hydrogen bonds and face-to-face π···π interactions: these sub-structures are the motifs I for each compound. A significant consequence of the different positions of the nitro group in the phenyl ring is the presence of the intramolecular N—H(hydrazonyl)···O(nitro) hydrogen bond present in the ortho derivative, but absent in the meta and para isomers. Apart from this, the different sites of the nitro groups have only a small influence on the internal structure of these motifs I, however they do play a major role in their packing and connections with other motifs. Among the interactions connecting the motifs are N—H···O(nitro), C—H···O(nitro), C—H···O(sulfonyl), C—H···π,N = O···π, S = O···π, face-to-face π···π, and S···S interactions. A survey was carried out on the arrangements of (O2)S-NHNHC fragments in R/S(O2)NHNHCOR compounds.

SYNTHESIS, ANTIAGGREGATION AND ANTITROMBOTIC ACTIVITIES OF NEW DERIVATIVES OF HYDROXYBENZOIC ACIDS WITH TAURIC FRAGMENT

A high prevalence of thrombotic disorders, insufficient effectiveness or safety of antithrombotic therapy is an urgent problem of modern healthcare. The main means of preventing thrombosis is acetylsalicylic acid. Despite its long history, aspirin attracts researchers in the fields of medicinal chemistry, biology, and medicine. The development of new antiplatelet agents, including chemical modification of the acetylsalicylic acid molecule, remains relevant. Modification of the acetylsalicylic acid molecule using amino acids and obtaining their salt forms makes it possible to maintain antiplatelet or antithrombotic properties, as well as to impart additional pharmacodynamic effects. In modern science, a lot of attention is paid to the sulfur-containing amino acid taurine. An analysis of modern scientific literature revealed the protective effect of taurine in diabetes mellitus and cardiovascular diseases, liver dysfunction, gastrointestinal tract, and kidney diseases.The aim of the article is to study synthesis of new compounds, determination of their physical characteristics and assessment of their antiplatelet and antithrombotic activities in vitro and in vivo.Materials and methods. To confirm the structure of the synthesized new derivatives of hydroxybenzoic acids with a taurine fragment by the acelation method, thin layer chromatography and NMR spectra were used. In vitro studies were carried out on the model of ADP-induced platelet aggregation according to the Born G. methods modified by V.A. Gabbasov. In vivo, the studies were carried out on the model of arterial thrombosis induced by the application of iron chloride in the following groups of animals: intact, with experimental diabetes mellitus and three-year-olds; the rate of bleeding from the tail vein was also evaluated.Results. New compounds – derivatives of ortho-, meta- and para-hydroxybenzoic acids with a taurine residue – were synthesized. A procedure for the preparation of N-hydroxybenzoyl taurine compounds and their salt forms have been described; their spectral characteristics and melting points have been determined. The synthesized compounds are superior to acetylsalicylic acid in solubility and are not inferior to it in antiplatelet and antithrombotic activities. The results of the in vitro antiplatelet activity assessment in a wide concentration range from 10-4M to 10-8M, are presented. It has been revealed that the dipotassium salt of N-(2-hydroxybenzoyl)taurine exhibits a less antiplatelet activity than the dipotassium salt of N-(3-hydroxybenzoyl)taurine. The most pronounced antiplatelet activity is exhibited by the compound N-(4-hydroxybenzoyl)taurine. In in vivo experiments on the model of arterial thrombosis in 3-year-olds or animals with experimental diabetes mellitus, carotid artery thrombosis occurred faster than in young or intact animals. A single preliminary oral administration of the test compounds prolonged the time of the thrombus formation, which makes it possible to conclude that they have an antithrombotic effect. In this study, the dipotassium salt of N-(3-hydroxybenzoyl)taurine exhibits a more pronounced activity than that of acetylsalicylic acid.Conclusion. Against the background of the modeled pathologies, the studied drugs showed the expected antithrombotic activity, in terms of the severity not inferior to that found in acetylsalicylic acid.

Synthesis and toxicity profile in 293 human embryonic kidney cells of the β D-glucuronide derivatives of ortho-, meta- and para-cresol

The formation of β-glucuronides is a major route by which mammals detoxify and remove breakdown products, such as l-tyrosine, as well as many xenobiotics, from their systems. In humans, dietary l-tyrosine is broken down largely by the action of the anaerobic gut bacterium C. difficile to p-cresol, providing a competitive advantage in the gut microbiota. Ortho- (o-) and meta- (m-), cresols, also present in the environment, may share a common degradative pathway. Relatively little work has been done on cresyl glucuronides. Here, a direct synthesis of o-, m-, and p-cresyl β-D-glucuronides from methyl 1,2,3,4 tetra-O-acetyl-β-d-glucuronate and the respective cresol employing trimethylsilyltriflate as promoter is presented. The protected intermediates were hydrolysed using aqueous sodium carbonate to yield the cresyl β-glucuronides. The toxicities of the o-, m- and p-cresyl β–D-glucuronides were compared. All three were less toxic to HEK293 cells than their respective cresol precursors: toxicity followed the order o < m < p for Na+ salts and o < p < m for Ca2+ salts. The m-cresyl-glucuronide Ca2+ salt and p-cresyl-glucuronide Na+ salt reduced colony formation by 11% and 9% (v. 30% reduction from the aglycone) respectively, whereas o-cresyl-glucuronide (both Na+ and Ca2+ salts), mildly stimulated HEK293 cell growth.

Photo-Fries reaction in acetoxyphenyl thiophenes

Two new acetoxyphenyl thiophenes with different conjugation length and undergoing the photo-Fries reaction upon exposure to UV light are presented. These molecules have been characterized in solution by means of different spectroscopic techniques in order to study the evolution and selectivity of the photo-induced reaction. During such a reaction, isosbestic points appear in the UV–vis spectra, indicating a good selectivity of the reaction for both the derivatives. By means of IR measurements, we follow the reaction and determine the kinetics and the quantum yield. The photoproducts are isolated by HPLC and characterized by 1H-NMR whose results confirm the formation of the ortho derivative as the most probable one and we estimate the degree of conversion of the reaction. High-level quantum mechanical calculations both in gas and solvated phase are employed to strongly support the interpretation of the experimental results, and assess the reaction product.

Phenylboronic Acids Probing Molecular Recognition against Class A and Class C β-lactamases.

Worldwide dissemination of pathogens resistant to almost all available antibiotics represent a real problem preventing efficient treatment of infectious diseases. Among antimicrobial used in therapy, β-lactam antibiotics represent 40% thus playing a crucial role in the management of infections treatment. We report a small series of phenylboronic acids derivatives (BAs) active against class A carbapenemases KPC-2 and GES-5, and class C cephalosporinases AmpC. The inhibitory profile of our BAs against class A and C was investigated by means of molecular docking, enzyme kinetics and X-ray crystallography. We were interested in the mechanism of recognition among class A and class C to direct the design of broad serine β-Lactamases (SBLs) inhibitors. Molecular modeling calculations vs GES-5 and crystallographic studies vs AmpC reasoned, respectively, the ortho derivative 2 and the meta derivative 3 binding affinity. The ability of our BAs to protect β-lactams from BLs hydrolysis was determined in biological assays conducted against clinical strains: Fractional inhibitory concentration index (FICI) tests confirmed their ability to be synergic with β-lactams thus restoring susceptibility to meropenem. Considering the obtained results and the lack of cytotoxicity, our derivatives represent validated probe for the design of SBLs inhibitors.

Effect of Head Structure on ATP Detection in Polydiacetylene Systems

ATP detection systems were formed using 10,12-pentacosadiynoic acid derivatives that had a tertiary amine group at their end. Ortho, meta, and para derivatives were synthesized and the receptiveness for ATP using these derivatives was characterized. A vesicle did not form with the ortho derivative. The para derivative, did form a vesicle but was unable to detect ATP. Only the meta derivative showed a color change from blue to red upon ATP detection. The size of the vesicle using a meta derivative was larger than that formed when using a para derivative. The meta derivative did not respond with a color change to analogs of ATP. The concentration of ATP that was able to be detected by the naked eye was 100 μM, and that by the UV spectrum was 50 μM. An ATP detection system was developed using polydiacetylene systems in this study.

Extended kinetic method study of the effect of ortho‐, meta‐, and para‐chlorination on the proton affinity of phenylalanine with full entropy analysis

AbstractAbsolute proton affinities (PAs) of phenylalanine, ortho‐chlorophenylalanine, meta‐chlorophenylalanine, and para‐chlorophenylalanine were determined using the extended kinetic method with full entropy analysis to investigate the effect of chlorination on the PA of phenylalanine. The measured absolute PAs of the molecules are 907.9 ± 2.3, 901.9 ± 2.2, 889.0 ± 2.8, and 904.9 ± 3.1 kJ·mol−1, respectively. The decrease and variations in the PAs upon chlorination are investigated based on the electronegativity of chlorine, polarizability, dipole moment, and the substituent effect. The effect of electronegativity of chlorine fails to explain differences in the PAs of the chlorine derivatives, and the ordering of the PAs is also not in line with polarizability. However, the ordering of dipole moments and substituent effects are, in part, consistent with that of the measured PAs except for the para and ortho derivatives, respectively. Thus, while no one molecular property fully explains the decrease in the absolute PA upon chlorination and its variation depending on the chlorination site, differences in dipole moments and the field effect provide the most plausible explanation for the observed changes.

1 J CH Coupling in Benzaldehyde Derivatives: Ortho Substitution Effect.

The natural J-coupling (NJC) method is applied to analyze the Fermi contact contribution of the NMR spin–spin coupling constant decomposing this contribution in terms of natural localized molecular orbitals. We investigated the influence of the basis set on the NJC analysis for the formyl group coupling constant (1JCHf) of benzaldehyde derivatives. NJC and other NBO analyses, like steric and natural Coulombic energy, were chosen to explain the influence of electron-donating and electron-withdrawing groups on 1JCHf for some substituted benzaldehydes (Me, OH, OMe, F, Cl, Br, I, and NO2). For the ortho derivatives, electronegative substituents near the C–Hf bond increase the 1JCHf coupling. This effect could be related to an increase in formyl carbon s character and changes in the carbon and hydrogen natural charges. This indicates that the substituents in ortho have a proximity effect on 1JCHf coupling mainly of electrostatic origin instead of the expected hyperconjugative interactions.

Spectroscopic studies of inclusion complexation between ortho derivatives of p-methylaminobenzoate and α- and γ-cyclodextrins

Using the steady-state and time-resolved spectroscopic techniques and quantum-chemical calculations, photophysical and photochemical properties of the two ortho derivatives of p-methylaminobenzoate (methyl o-methoxy p-methylaminobenzoate (I) and methyl o-hydroxy p-methylaminobenzoate (II)) have been studied in binary mixture THF-H2O and aqueous solutions containing different concentrations of α- and γ-CD. Nonlinear solvatochromic shifts of the absorption and fluorescence bands were observed for both fluorophores in a mixture of polar aprotic (THF) and polar protic (H2O) solvents. This nonlinearity has been explained in terms of the non-specific (dielectric enrichment of the solvent around the polar solute) and specific (hydrogen bond) solute-solvent interactions. Spectroscopic measurements were used to investigate the role of H-bonding solute-solvent interactions, and the excited-state intramolecular proton transfer process in the formation of inclusion complexes between fluorophore and cyclodextrins. The obtained results were used to calculate, according to Benesi–Hildebrand's plot and nonlinear least-squares regression analysis, equilibrium constants of the fluorophore-cyclodextrin inclusion complexes. Performed analysis indicates also that both 1:1 and 1:2 inclusion complexes were formed between studied compounds and α- and γ-cyclodextrins.

The influence of anchoring group position in ruthenium dye molecule on performance of dye-sensitized solar cells

The effect of anchoring group position and, in consequence, the orientation of the ruthenium dye molecule on titania surface on the performance of dye-sensitized solar cells has been studied intensively. Three model ruthenium sensitizing dyes bearing carboxylic anchoring group in ortho, meta or para position were synthesized and well characterized by spectroscopic, electrochemical, photophysical and photochemical measurements. The results were confronted with the quantum-mechanical calculations and discussed. The para derivative has been found as the most effective sensitizer with the cells efficiency twice higher than the meta and four times higher than the ortho derivatives.

Photoisomerization of Trans Ortho-, Meta-, Para-Nitro Diarylbutadienes: A Case of Regioselectivity.

A series of ortho-, meta- and para-substituted trans-nitro aryl (phenyl and pyridyl) butadienes have been synthesized and characterized. The effect of substitution and positional selectivity on their fluorescence and photoisomerization were systematically investigated. Among all dienes, meta- and para-nitro phenyl-substituted derivatives exhibit remarkable solvatochromic emission shifts due to intramolecular charge transfer. On the other hand, ortho derivatives undergo regioselective isomerization upon photoexcitation in contrast to inefficient isomerization of para and meta nitro-substituted dienes. Single crystal X-ray analysis revealed existence of intramolecular hydrogen bonding between the nitro group and the hydrogen of the proximal double bond. This restricts the rotation of the proximal double bond thereby allowing regioselective isomerization. The observations were also supported by NMR spectroscopic studies.

Derivatization of (quinolin-8-yl)phosphinimidic amides via ortho-lithiation revisited.

5The direct ortho-lithiation of N-H containing (quinolin-8-yl)phosphinimidic amides by reaction with 1 equiv. of n-BuLi described by Wang and co-workers has been re-examined. The multinuclear magnetic resonance ((1)H, (2)H, (7)Li, (13)C, (15)N and (31)P) study of the species formed in the monolithiation of N-(tert-butyl)-P,P-diphenyl-N'-(quinolin-8-yl)phosphinimidic amide 5 with n-BuLi in THF showed that proton abstraction occurred exclusively and quantitatively at the NH. The combination of the NMR results with a DFT study made it possible to describe the structure of the N-lithiated species 9 as a dimer consisting of an eight-membered ring showing two lithium ions triply coordinated to nitrogen atoms corresponding to the deprotonated amine and aminoquinoline moieties of different monomers. The formation of a polymer featuring the same coordination mode couldn't be excluded. In addition, optimized conditions for the efficient derivatization of 5 via ortho-lithiation were realised. The reaction of 5 with 2.4 equiv. of t-BuLi in THF in the temperature range of -80 °C to 25 °C for 3 h afforded a N,C(ortho)-dilithiated species that was trapped with a series of electrophiles leading to new functionalized ortho derivatives of 5 in good yields.

Prediction of ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous acetonitrile

Abstract The second-order rate constants k for the alkaline hydrolysis of phenyl esters of meta-, para- and ortho-substituted benzoic acids, X-C6H4CO2C6H5, in aqueous 50.9% acetonitrile have been measured spectrophotometrically at 25°C. The log k values for meta and para derivatives correlated well with the Hammett σm,p substituent constants. The log k values for ortho-substituted phenyl benzoates showed good correlations with the Charton equation, containing the inductive, σI, resonance, σ○ R, and steric, E s B, and Charton υ substituent constants. For ortho derivatives the predicted (log k X)calc values were calculated with equation (log k ortho)calc = (log k H AN)exp + 0.059 + 2.19σI + 0.304σ○ R + 2.79E s B − 0.0164ΔEσI — 0.0854ΔEσ○ R, where DE is the solvent electrophilicity, ΔE = E AN — E H20 = −5.84 for aqueous 50.9% acetonitrile. The predicted (log k X)calc values for phenyl ortho-, meta- and para-substituted benzoates in aqueous 50.9% acetonitrile at 25°C precisely coincided with the experimental log k values determined in the present work. The substituent effects from the benzoyl moiety and aryl moiety were compared by correlating the log k values for the alkaline hydrolysis of phenyl esters of substituted benzoic acids, X-C6H4CO2C6H5, in various media with the corresponding log k values for substituted phenyl benzoates, C6H5CO2C6H4-X.

Porphyrin-Sensitized Solar Cells: Effect of Carboxyl Anchor Group Orientation on the Cell Performance

The effect of the orientation of the porphyrin sensitizer onto the TiO2 surface on the performance of dye-sensitized solar cells (DSSCs) is reported. Free-base and zinc porphyrins bearing a carboxyl anchoring group at the para, meta, or ortho positions of one of the meso-phenyl rings were synthesized for application in Grätzel-type photoelectrochemical cells. The remainder of the meso-phenyl rings was substituted with alkyl chains of different length to visualize any aggregation effects. Absorption and fluorescence studies were performed to characterize and observe spectral coverage of the thirteen newly synthesized porphyrin derivatives. Photoelectrochemical studies were performed after immobilization of porphyrins onto nanocrystalline TiO2 and compared with DSSC constructed using N719 dye as reference. The performance of DSSCs with the porphyrin anchoring at the para or meta position were found to greatly exceed those with the anchoring group in the ortho position. Additionally, cells constructed using zinc porphyrin derivatives outperformed the free-base porphyrin analogs. Better dye regeneration efficiency for the zinc porphyrin derivatives compared to their free-base porphyrin analogs, and for the meta and para derivatives over the ortho derivatives was evaluated from electrochemical impedance spectroscopy studies. Femtosecond transient absorption spectroscopy studies were performed to probe the kinetics of charge injection and charge recombination with respect to the orientation of porphyrin macrocycle on TiO2 surface. The ortho porphyrin derivative with an almost flat orientation to the TiO2 surface revealed fast charge recombination and suggested occurrence of through-space charge transfer. The overall structure-performance trends observed for the present porphyrin DSSCs have been rationalized based on spectral, electrochemical, electrochemical impedance spectroscopy, and transient spectroscopy results.

Prediction of ortho substituent effect in alkaline hydrolysis of substituted phenyl benzoates in aqueous acetonitrile

The second-order rate constants k (dm3mol−1s−1) for alkaline hydrolysis of meta-, para- and ortho-substituted phenyl esters of benzoic acid, C6H5CO2C6H4-X, in aqueous 50.9% (v/v) acetonitrile have been measured spectrophotometrically at 25 °C. In substituted phenyl benzoates, C6H5CO2C6H4-X, the substituent effects log kX − log kH in aqueous 50.9% acetonitrile at 25 °C for para, meta and ortho derivatives showed good correlations with the Taft and Charton equations, respectively. Using the log k values for various media at 25 °C, the variation of the ortho substituent effect with solvent was found to be precisely described with the following equation: Δlog kortho = log kortho − log kH = 1.57σI + 0.93σ°R + 1.08EsB − 0.030ΔEσI − 0.069ΔEσ°R, where ΔE is the solvent electrophilicity, ΔE = ES − EH20, characterizing the hydrogen-bond donating power of the solvent. We found that the experimental log k values for ortho-, para- and meta-substituted phenyl benzoates in aqueous 50.9% acetonitrile at 25 °C, determined in the present work, precisely coincided with the log k values predicted with the equation (log kX)calc = (log kHAN)exp + (Δlog kX)calc where the substituent effect (Δlog kX)calc was calculated from equation describing the variation of the substituent effect with the solvent electrophilicity parameter, using for aqueous 50.9% CH3CN the solvent electrophilicity parameter, ΔE = −5.84. In going from water to aqueous 50.9% CH3CN, the ortho inductive term grows twice less as compared with the para polar effect. Copyright © 2013 John Wiley & Sons, Ltd.

Azobenzene-functionalized N-heterocyclic carbenes as photochromic ligands in silver(i) and gold(i) complexes

The reaction of meta- and para-bromomethylene-azobenzenes with 1-methyl-imidazole yields the respective meta-/para-functionalized azobenzenes tagged with an imidazolium group. Similar reactions of ortho- and para-bromo-azobenzene with imidazole and successive quaternation with benzylbromide give the analogues, with an imidazolium group in ortho/para substituted azobenzenes. With the exception of the ortho derivative, all imidazolium salts could be transformed into their respective silver(i) complexes by reaction with Ag2O. Transmetallation of these silver(i) complexes with (Me2S)AuCl gives the azobenzene-containing complexes (NHC)AuCl. Two of these formed crystals suitable for X-ray diffraction, which revealed the typical linear coordination geometry of the NHC-Au-Cl moiety. All gold complexes feature E→Z photo-isomerisation upon irradiation with UV light. The thermal back reaction to the E-isomers is relatively slow and comparable to that of other azobenzene compounds.

Chemical Enhancement of the Surface Enhanced Raman Scattering Signals of Anilines via Their &amp;lt;i&amp;gt;Ortho&amp;lt;/i&amp;gt;-Substituents

While Raman spectroscopy is a useful method for analyzing many organic compounds, it is limited by relatively low sensitivity. Therefore, Surface Enhanced Raman Spectroscopy (SERS) based on the adsorption of organic analytes onto gold or silver nanostructures has been used to enhance the signal of chemicals presented at very low concentrations. Although the plasmonic effect of SERS has been shown to play a large role in signal enhancement, the significance of the chemical effect due to the analyte chemisorption on the gold or silver surface is less well understood. In this study, the role of aniline substituents is examined by probing the SERS intensities of various anilines in silver and gold colloids using a Raman spectrometer with an excitation wavelength of 785 nm. The SERS enhancement factors and detection limits for aniline and its mono- and di-substituted ortho derivatives are determined and compared. Both the steric requirements of chemisorption and the inductive effects of electron-withdrawal due to the substituents affect the signal intensities of various vibrational modes of the amino group and the aromatic ring. The degree of enhancement is also related to the methods for preparing the silver and gold colloids, which are characterized by probing the nanoparticle morphology and its degree of aggregation using transmission electron microscopy (TEM).

Correlation between electrochemical and theoretical studies on the leishmanicidal activity of twelve Morita-Baylis-Hillman adducts

Enzymatic bioreduction of nitro groups plays an important role on the activity of biologically active nitroaromatic compounds. Electrochemical methods are useful tools to simulate in vivo metabolic processes. This work presents electrochemical studies in aprotic media (N, N-dimethylformamide (DMF) plus tetrabutylammonium perchlorate (TBAP) 0.1 mol L-1) using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and square wave voltammetry (SWV) of twelve Morita-Baylis-Hillman adducts (MBHA) with significant leishmanicidal activity. To facilitate the analysis, the molecules were grouped in four classes according to the side chain. CV studies show three up to four reduction waves, in which the first two waves are related to nitro group reduction. The other waves (presenting more negative potential) refer to the reduction of the α,β-unsaturated carbonyl or to the nitrile activated olefin side-chain. Ortho adducts present facilitated reduction in comparison to the other isomers (meta and para) possibly due to hydrogen bond formation between the benzylic-OH and the nitro group, which stabilizes the reduction product (anion radical nitro) more efficiently than the original compound. Ortho derivatives also present higher leishmanicidal activity upon comparison to the other derivatives of each class. Conformational studies using HF/6-31+G(d)/PCM as a calculation level highlight this effect. Molecular hardness (N) and atomic charges (Q N) values corroborate the obtained experimental data.

Synthesis, spectra and properties of the first protono- and ionogenic tris-dioximate iron(II) clathrochelates

Water-soluble ribbed-functionalized iron(II) cage complexes with iono- and protonogenic substituents were obtained by nucleophilic substitution of the reactive chlorine atoms of mono-, di- and hexachloroclathrochelate precursors with thiolate ions – the derivatives of ortho-, meta- and para-mercaptobenzoic acids and sodium 3-mercapto-1-propanesulfonate – as nucleophiles. The complexes obtained were characterized using elemental analysis, MALDI–TOF and ESI mass spectrometry, IR, UV–Vis, 1H and 13C{1H} NMR spectroscopies; their electrochemical properties were studied by cyclic voltammetry. The oxidized iron(III)- and reduced iron(I)-containing clathrochelate species are chemically unstable because of the destabilizing electronic effects of the ribbed sulfide substituents and the substantial structural and electronic changes in the clathrochelate framework after the reduction process, respectively.