Tetraphenylphosphonium carboxylates and sulfonates. Synthesis and structure

The reaction of the pentaphenyphosphorus solvate Ph₅P·1/2PhH (I) with carboxylic and sulfonic acids was used to synthesize tetraphenylphosphonium carboxylates Ph₄POC(O)R, R = C₆H₄(2-OH) (II), C₆H₄ (2-COOH) (III), H (IV), Me (V), CCl₃ (VI), Ph (VII), PhCH=CH (VIII), CH₂CH₂C(O)OH (IX), CH=CHC(O) OH(X), and CH₂C(O)OH (XI) and tetraphenylphosphonium sulfonates Ph₄POSO₂Ar, Ar = Ph (XII), C₆H₄Me₄ (XIII), and C₆H₃(-COOH)(4-OH) (XIV). Compound XII was also prepared from compound I and SO₃ in benzene. According to X-ray diffraction data, the crystals of I contain two types of crystallographically independent molecules with a slightly distorted trigonal-bipyramidal configuration [Ia, CaxPCax 178.44(8)°, P- C_ax 1.985(2), 1.987(2) Å, P-C_eq 1.854(2), 1.846(2), 1.840(2) Å; Ib, C_axPC_ax 178.45(9)°, P-C_ax 1.980(2), 1.975 (2) Å, P-C_eq 1.840(2), 1.846(2), 1.854(2) Å]. In the cations of compounds II, III and XIV, the coordination of the phosphorus atom is tetrahedral [CPC angle: II, 106.2(2)?111.6(1)°; III, 104.01(6)?113.03(6)°; XIV, 107.54 (6)?112.79(6)°]; the anions contain intramolecular O-H?O hydrogen bonds between the hydroxyl hydrogen atom and carboxyl oxygen atom (II, 1.34; III, 1.23; and XIV, 1.83 Å).     

Preparation,molecular and crystal structures of 3-(1-amino-2,2,2-trifluoroethylidene)-1,1,4,5,6,7-hexafluoroindan-2-one, 2-amino-1,1,4,5,6,7-hexafluoro-3-trifluoroacetylindene,and their complexes with dioxane and pyridine

3-(1-Amino-2,2,2-trifluoroethylidene)-1,1,4,5,6,7-hexafluoroindan-2-one (2) is synthesized by the interaction between 3-(1-amino-2,2,2-trifluoroethylidene)-2-imino-1,1,4,5,6,7-hexafluoroindan (1) and isopropylnitrite, and 2-amino-1,1,4,5,6,7-hexafluoro-3-trifluoroacetylindene (3) is prepared by hydrolysis. Single crystals are grown, and the molecular and crystal structure of enaminoketones obtained, the complex of compound 2 with 1,4-dioxane, and the complex of compound 3 with pyridine is studied. DFT calculations have been performed to find the complex formation energies of compounds 2 and 3 with dioxane and pyridine in the gas phase.     

Synthesis of novel 5,6,7,8,9,10-hexahydropyrimido[4,5-b]quinoline derivatives for antimicrobial and anti-oxidant evaluation

Because of the well-known chemotherapeutic activity of pyrimidoquinolines, a new series of the title compounds were synthesized and biologically screened for their antimicrobial and anti-oxidant activities. The intermediate compound, 2-amino-1-cyclohexyl-4-(3,4-dimethoxyphenyl)-1,4,5,6,7,8-hexahydroquinoline-3-carbonitrile (2), was prepared and allowed to react with oxalyl chloride to give the corresponding strategic starting material, 10-cyclohexyl-5-(3,4-dimethoxyphenyl)-4-oxo-3,4,5,6,7,8,9,10-octahydropyrimido[4,5-b]quinoline-2-carbonyl chloride 3. Compound 3 underwent diverse reactions with amines to give the corresponding carboxylic amides 4, with alcohols to give the carboxylic esters 5 and with hydrazine to give the carbohydrazide 8. Compound 8 reacted with aldoses to give the corresponding polyhydroxy(-)alkyl Schiff bases 9, which upon reaction with thioglycolic acid afforded the thiazolidinone-C-acyclic nucleosides 10. Several other pyrimidoquinolines incorporated to oxadiazole, iminothiazolidinones and thiadiazoles were synthesized starting from the 2-carbohydrazide derivative 8. Most of the newly prepared derivatives showed considerable antimicrobial activity against Gram +ve and Gram ?ve bacteria and anti-oxidant activity.     

Crystal structures of triphenylamylphosphonium iodide [Ph<Subscript>3</Subscript>AmP]I and triphenylamylphosphonium tetraiodide [Ph<Subscript>3</Subscript>AmP]I<Subscript>4</Subscript>

By reaction of triphenylamylphosphonium iodide [Ph₃AmP]I (I) with antimony iodide in acetone, triphenylamylphosphonium tetraiodide [Ph₃AmP]₂I₄ (II) was synthesized. Crystals of I consist of triphenylamylphosphonium cations and iodine anions. Compound II contains two types of tetrahedral triphenylamylphosphonium cations, iodine anions, and [I₃]^? anions. Atoms P have a distorted tetrahedral coordination in cations I and II (the CPC angles are 106.48(12)°–111.25(12)° in I and 107.05(9)°–112.62(10)° in II). The centrosymmetric trinuclear [I₃]^? anion in II is nearly linear (the I(2)I(1)I(3) angle is 178.65°, the I(1)–I(2) and I(1)–I(3) bond lengths are 2.8925(2) Å and 2.9281(2) Å, respectively).     

Benzyl group conformation in 4-benzyl-4-hydroxypiperidines

The high-resolution ¹H and ¹³C NMR spectra of eight 4-benzyl-4-hydroxypiperidines 1–8 were recorded in CDCl₃ and analyzed. In 2, the conformation of the equatorial benzyl group at C(4) was established as an equilibrium mixture of A [the phenyl group is gauche with respect to OH and C(5)] and B [the phenyl group is gauche with respect to OH and C(3)], whereas in 3-alkyl-4-benzyl-4-hydroxypiperidines 3–8, the favored conformation of the benzyl group at C(4) is A. In 1, the axial benzyl group at C(4) adopts the gauche conformations A′ [the phenyl group is gauche with respect to OH and C(3)] and B′ [the phenyl group is gauche with respect to OH and C(5)], in which the phenyl ring of the benzyl group is gauche with respect to the OH group. The HF/DFT B3LYP/6-3G* hybrid calculations of model systems 1′–3′ also support these conformations. The ¹³C data reveal that the equatorial methyl group at C(3) exerts a shielding influence on the methyl-bearing carbon and the magnitude of the α effect was found to be approximately ?1.5 ppm. The parameters of the ¹³C substituent in the benzyl group show that the the α effect of the equatorial benzyl group is considerably higher in 3-ethyl tertiary alcohol 7 than in 3-methyl tertiary alcohol 3 and 4-benzyl-t(4)-hydroxypiperidine 2. This may be explained if we take into account the different conformations of the ethyl group in t(4)-hydroxy-3-ethyl-2,6-diphenylpiperidine 12 and 3-ethyl tertiary alcohol 7.     

Synthesis and structures of organoantimony and organobismuth derivatives of 4-sulfophenol and 2,4-disulfophenol

Tetraphenylbismuth 4-hydroxybenzenesulfonate (I) and tetraphenylantimony 4-hydroxybenzenesulfonate (II) are synthesized in yields up to 80% by the reaction of pentaphenylbismuth and pentaphenylantimony, respectively, with 4-sulfophenol. Compounds I and II are also prepared by the ligand redistribution reaction from pentaphenyl compounds of bismuth and antimony and triphenylbismuth bis(4-hydroxybenzenesulfonate) and triphenylantimony bis(4-hydroxybenzenesulfonate), respectively, in yields up to 87%. The recrystallization of compounds I and II from water gives crystalline hydrates Ph₄BiOSO₂C₆H₄(OH-4) · H₂O (III) and Ph₄SbOSO₂C₆H₄(OH-4) · H₂O (IV). Pentaphenylbismuth and pentaphenylantimony react with 2,4-disulfophenol in acetone, regardless of the ratio of the starting reactants, to form bis(tetraphenylbismuth) 4-hydroxybenzene-1,3-disulfonate (V) and bis(tetraphenylantimony) 4-hydroxybenzene-1,3-disulfonate (VI) in yields up to 74%. According to X-ray diffraction data, coordination of the bismuth atoms in compound I is trigonal-bipyramidal with the axial oxygen atom of the 4-hydroxybenzenesulfonate group (Bi···O 2.764 Å). In compound II, coordination of the Sb atom is tetrahedral (CSbC angles 106.2°–112.3°). In crystal III, the distances between the central atom and the nearest oxygen atoms of the arenesulfonate group and the hydrate water molecule are 3.094 and 3.125 Å, respectively. Crystals V and VI consist of doubly charged anions of 2,4-disulfophenol and several distorted tetrahedral cations of tetraphenylbismuthonium (CBi(1)C, CBi(2)C angles and Bi(1)-C, Bi(2)-C bond lengths vary in the intervals 102.1°–122.7°, 105.4°–114.0° and 2.103–2.230, 2.187–2.209 Å, respectively) and tetraphenylantimonium (CSb(1)C, CSb(2)C angles and Sb(1)-C, Sb(2)-C bond lengths 106.3°–112.2°, 101.3°–122.4° and 2.095–2.110, 2.092–2.123 Å, respectively). The Bi(1) and Sb(2) atoms are coordinated by one of the oxygen atoms of the 2,4-disulfophenol anions (distances Bi(1)···O(3) 2.803, Sb(2)···O(1), 2.704 Å).     

Improved synthesis and low-temperature performance of a series of saturated α-branched fatty acids

Five saturated α-branched fatty acids, also known as Guerbet acids, including α-propylhexyl acid (G ₁ ), α-butylhexyl acid (G ₂ ), α-propyloctyl acid (G ₃ ), α-butyloctyl acid (G ₄ ), and α-hexyloctyl acid (G ₅ ), were synthesized in high yields by four-step reaction. Colorless, almost odorless, and oily products were obtained with high purity, whose structures were confirmed by GC, ¹H/¹³C NMR, and ESI–MS characterization. G ₁ , G ₃ , and G ₄ had pour points lower than ?60 °C, while G ₂ and G ₅ showed higher pour points (?42 °C and 6 °C, respectively) because of their molecular symmetry. Considering the low-temperature properties, G ₁ , G ₃ , G ₄ , and even G ₂ held great potential applications in the lubricant and oilfield.     

Synthesis and structure of bischelate gallium complexes (dpp-bian)Ga(acac) and (dpp-bian)Ga(2,2´-bipy) (dpp-bian is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene)

A reaction of digallane [(dpp-bian)Ga—Ga(dpp-bian)] (1) (dpp-bian is the 1,2-bis[(2,6-disopropylphenyl)imino]acenaphthene) with one equivalent of I₂ leads to oxidation of (dpp-bian)^2– in compound 1 to (dpp-bian)–and gives [(dpp-bian)GaI—GaI(dpp-bian)] (2). In the reaction of compound 2 with two equivalents of (acac)Na, not only exchange of the iodide and acetylacetonate ions takes place, but also a transfer of electrons from the metal—metal bond to dpp-bian with the formation of the complex [(dpp-bian)Ga(acac)] (3), in which the dpp-bian ligand is a dianion. A reaction of digallane 1 with 2,2´-bipyridyl at 200 °C in toluene in a sealed tube leads to the reduction of 2,2´-bipyridyl and gives the complex [(dpp-bian)Ga(bipy)] (4), which contains two different chelate redox-active ligands. The new compounds were characterized by IR (3, 4), NMR (3), and ESR spectra (4), the structures of both derivatives were established by X-ray diffraction.     

Nitrogen-containing analogues of boron difluoride benzoylacetonate: synthesis,structure, luminescence,and quantum chemical modeling

Nitrogen-containing analogues of boron difluoride benzoylacetonate (1), i.e., boron difluoride ketoiminates (boron difluoride 3-amino-1-phenyl-2-buten-1-onate (2) and 3-methylamino-1-phenyl-2-buten-1-onate (3)), were taken as examples to study the influence of a substituent (H, Me) at the nitrogen atom on structure and spectral-luminescent properties. The replacement of the oxygen atom with the nitrogen atom in compound 1 led to a bathochromic shift of the monomeric luminescence maximum. Quantum chemical modeling of absorption spectra for compound 2 was carried out. In contrast to compounds 1 and 3, crystals of compound 2 are characterized by the formation of J-aggregates and excimers on their basis, which leads to a bathochromic shift of the luminescence spectrum and an increase in the luminescence intensity.     

Tetraphenylantimony perrhenate and tetraphenylantimony chlorate: Syntheses and structures

The reaction of tetraphenylantimony chloride with sodium perrhenate or potassium chlorate yields tetraphenylantimony perrhenate (I) and tetraphenylantimony chlorate (II), respectively. Complex I was also synthesized from pentaphenylantimony and triphenylantimony diperrhenate in toluene. According to X-ray diffraction, crystals I and II consist of almost regular tetrahedral tetraphenylstibonium cations (CSbC, 109.4(2)°–109.5(7)° in I and 109.1(1)°–109.6(1)° in II) and [ReO₄]^? (OreO, 107.6(3)°–113.3(5)°) and [ClO₃]^? (OClO, 96.3(9)°, 116.4(5)°) anions, respectively. The average Sb-C bond lengths (2.094(3) Å in I, 2.097(2) Å in II) are close to the sum of the covalent radii of the Sb and C atoms. The average distances Re-O in complex I (1.672(4) Å) and Cl-O in complex II (1.315 Å) correspond to multiple bonds.     

Open Pentaruthenium Cluster Complexes Formed from the Addition of Benzoic Acid to Ru<Subscript>5</Subscript>(C)(CO)<Subscript>15</Subscript>

Two isomers of Ru₅(C)(CO)₁₄(O₂CC₆H₅)(μ-H): Ru₅(C)(CO)₁₄(η²-O₂CC₆H₅)(μ-H), 2 and Ru₅(C)(CO)₁₄(μ-O₂CC₆H₅)(μ-H), 3 were obtained from the reaction of Ru₅(C)(CO)₁₅ with benzoic acid (PhCO₂H). Both compounds were characterized structurally by X-ray diffraction analysis. Compound 2 contains an opened pentaruthenium cluster with a chelating benzoate ligand on the ruthenium atom that was opened. Compound 3 contains an opened pentaruthenium cluster with a benzoate ligand on that bridges a pair of ruthenium atoms which are not mutually bonded. Compound 2 can be converted partially to 3 and 3 partially back to 2 and they form a 1.54/1.0 ratio (3/2) at equilibrium in solution at 95 °C.     

Spectroscopic characterizations,X-ray studies,and electronic circular dichroism calculations of two alkaloid triterpenoids

Two alkaloid triterpenoids formulated as C₂₆H₃₅NO₃ (1) and C₃₀H₄₅NO₂ (2) were isolated from the timer tree Aphanamixis grandifolia. The structure of 1 and 2 was determined by IR, HRESIMS, 1D, and 2D-NMR. Compound 1 was confirmed by X-ray single crystal diffraction. Compound 1 crystallizes in the monoclinic, space group C₂ with unit cell parameters a = 53.195(4) Å, b = 7.6339(8) Å, c = 11.202(2) Å, β = 94.6520(2)°. Intermolecular hydrogen bonding and π–π stacking were presented in the molecular packing of 1. The absolute configurations of 1 and 2 were established by comparison of experimental circular dichroism properties with their electronic circular dichroism predicted by molecular modeling DFT calculations.     

A Tetragonal and an Uncommon Trigonal Dicobalt Paddlewheel Compound

Two dicobalt compounds containing Co–Co bonds with DAniF ligands (DAniF = N,N′-di-p-anisylformamidinate) were synthesized and characterized by X-ray crystallography. One has a typical tetragonal paddlewheel structure, Co₂(DAniF)₄ (1), while the other one has a rare trigonal paddlewheel structure with three formamidinate ligands spanning a low oxidation state in the Co ₂ ³⁺ unit in Co₂(DAniF)₃ (2). The singly bonded Co–Co distance in the Co ₂ ⁴⁺ unit in 1 is 2.3580(16) Å while the Co–Co bond distance in 2 is 2.3773(5) Å. The average torsion angles are 10.46° and 2.34° for 1 and 2, respectively. Compound 1 is diamagnetic but 2 is paramagnetic as shown by the ¹H NMR spectra.     

Synthesis and anticancer activities of 1,4-phenylene-bis-<Emphasis Type="Italic">N</Emphasis>-acetyl- and <Emphasis Type="Italic">N</Emphasis>-phenylpyrazoline derivatives

Novel 1,4-phenylene-bis-N-acetyl- (3a–h) and bis-N-phenylpyrazoline derivatives (4a–h) were obtained by addition of hydrazine hydrate and phenylhydrazine to bis-chalcone derivatives (1a–h) in acetic acid and acetic acid/ethanol for 4 and 8 h in reflux conditions, respectively. The structures of the obtained bis-N-acetylpyrazoline and bis-N-phenylpyrazoline derivatives were characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic methods and elemental analysis. Compounds 3a–h and 4a–h were investigated to evaluate their anticancer activities against C6 (rat brain tumor cells) and HeLa (human uterus carcinoma) in vitro using a dose-dependent assay from 5 to 100 μM with 5-fluorouracil (5-FU) as standard anticancer drug. Compound 3a showed higher cell-selective activity compared with 5-FU against HeLa cells. Compounds 3a–h (except 3d) were shown to have better activities than 5-FU against both cells, particularly at high concentration. Compound 4c showed higher cell-selective activity compared with 5-FU against C6 cells. Compound 3a may be particularly promising as an anticancer drug against HeLa cells.     

Synthesis,structure, and properties of Schiff base iodobismuthate and its alteration in DMSO solution

New hybrid iodobismuthates (C₁₂H₁₈N₂)(BiI₄)₂ (1, C₁₂H₁₈N₂ is N,N´-bis(1- methylethylidene)-1,4-benzоdiammonium dication) and (C₆H₄(NH₃)₂) [Bi₂I₈?2DMSO]?4DMSO (2, C₆H₄(NH₃)₂ is p-phenylenediammonium dication) were synthesized and their crystal structures were established. Compound 1 crystallizes in the space group P2₁/n, a = 7.632(4), b = 13.471(6), c = 14.556(5) Å, β = 93.57(4)°; compound 2 crystallizes in the space group P\(\overline 1 \), a = 9.208(4), b = 12.203(5), c = 13.600(5) Å, α = 110.20(3)°, β = 97.28(4)°, γ = 110.04(4)°. In the crystal structure of compound 1, one-dimensional infinite BiI ₄ ^– polyanions are linked into a three-dimensional structure by N,N'-bis(1-methylethylidene)- 1,4-benzоdiammonium dications through N–H…I and C–H…I hydrogen bonds. Compound 1 is stable up to 200 °С, optical studies showed that it has a band gap of 2.15 eV. The recrystallization of compound 1 from DMSO is accompanied by the transformation of chain BiI ₄ ^– anions to binuclear [Bi₂I₈?2DMSO]^2– anions, while the azomethine cation decomposes to form a p-phenylenediammonium dication.     

Crystal structures of two new dinuclear Ag(I) complexes constructed from 4,4′-biphenyldicarboxylic acid and N-containing ligands

The reaction of silver 4,4′-biphenyldicarboxylate with 1,3-diaminopropane (DAP) and 2-amino-5-methylpyridine (AMP) respectively results in the formation of two dinuclear silver(I) complexes: [Ag₂(DAP)₂](BPC)·2H₂O (1) and [Ag₂(BPC)(AMP)₄]·2H₂O (2), where BPC is 4,4′-biphenyldicarboxylate. The complexes are characterized by elemental analysis and X-ray crystallography. Complex 1 crystallizes in the triclinic system, P-1 space group, a = 8.585(2) Å, b = 8.849(2) Å, c = 9.890(3) Å, α = 107.893(3)°, β = 94.139(3)°, γ = 113.202(3)°, V = 640.9(3) ų, Z = 1. Complex 2 crystallizes in the triclinic system, P-1 space group, a = 11.818(3) Å, b = 13.132(4) Å, c = 13.281(4) Å, α = 92.571(4)°, β = 96.425(3)°, γ = 102.142(4)°, V = 1997.5(10) ų, Z = 2. Complex 1 consists of a macrocyclic dinuclear silver(I) dication, a 4,4′-biphenyldicarboxylate anion, and two water molecules of crystallization. Each Ag atom is in a linear coordination. Complex 2 consists of a dinuclear silver(I) complex molecule and two water molecules of crystallization. Each Ag atom is in a T-shaped coordination. The Ag...Ag separations are 5.127(2) Å in 1 and 3.172(2) Å in 2.     

Single crystal x-ray diffraction study of dioxane,pyrazine, and pyridine complexes of 3-(1-amino-2,2,2-trifluoroethylidene)-2-imino-1,1,4,5,6,7-hexafluoroindan

Single crystals of complexes of 3-(1-amino-2,2,2-trifluoroethylidene)-2-imino-1,1,4,5,6,7-hexafluoroindan (1) with 1,4-dioxane, pyrazine, and pyridine have been synthesized. Their structure was investigated by X-ray analysis. In crystals of the dioxane complex, compound 1 is present together with its tautomer — 2-amino-3-(1-imino-2,2,2-trifluoroethyl)-1,1,4,5,6,7-hexafluoroindene (1a), and these compounds are in an equilibrium ratio of ～60:40. Gas-phase quantum chemical calculations have been performed to examine the possibility of a tautomeric equilibrium of enaminoimine 1 in the corresponding complexes.     

Molecular and crystal structure of 15-acetylsongorine and songoramine isolated from <Emphasis Type="Italic">Aconitum szechenyianum</Emphasis> Gay

Two napelline skeletal diterpenoid alkaloids 15-acetylsongorine, C₂₄H₃₃NO₄ I, and songoramine, C₂₂H₂₉NO₃ II, were first isolated from the roots of Aconitum Szechenyianum Gay. The crystal structures were determined by X-ray single-crystal diffraction analysis. The crystal I is the triclinic system with space group P1 having unit cell parameters of a = 9.360(8) Å, b = 11.593(9) Å, c = 11.830(16) Å, α = 113.223(15)°, β = 105.950(16)°, γ = 101.296(12)°, and Z = 2. Hydrogen bonds O–H···O and O–H···N joint the molecules into dimer. The crystal II belongs to the orthorhombic system with space group P2₁2₁2₁ having unit cell parameters of a = 8.950(2) Å, b = 13.272(3) Å, c = 15.454(4) Å and Z = 4. The O–H···O hydrogen bonding interaction links the molecule into linear chains. The distortion of rings of compound I and II were evaluated by calculation of the Cremer and Pople puckering parameters. The presence of the C–O–C bond in the compound II results in the changes of ring conformations compared with that of the compound I.     

Synthesis,characterization, crystal structure and cytotoxicity of 2,4-bis(selenomethyl)quinazoline

Organoselenium compounds have already been reported to be good anticarcinogenic candidates. A new selenoquinazoline derivative, 2,4-bis(selenomethyl)quinazoline (compound 1), has been synthesized, spectroscopically characterized and its crystal structure has been studied. An intermolecular coupling between C₂ and \( {\text{H}}_{5}^{\prime } \) in the Heteronuclear Multiple Bond Correlation (HMBC) experiment has been observed. Assuming that the head-to-tail overlap of parallel molecules (as identified by X-ray diffraction) remains in solution to give bimolecular entities, the π–π interaction enables heteronuclear coupling between the former atoms with a three-bond distance [C₂···(π–π)···\( {\text{C}}_{5}^{\prime } \)–\( {\text{H}}_{5}^{\prime } \)]. The crystal structure of compound 1 has been solved by X-ray diffraction. It crystallizes in triclinic system, space group P?1. Unit cell parameters are a = 7.4969(7) Å, b = 8.7008(8) Å, c = 10.1666(9) Å, α = 110.215(2)°, β = 90.354(2)°, γ = 115.017(1)°. Linear chains in crystals of compound 1 are generated by C–H···Se and Se···Se bonds between molecules. Furthermore, head-to-tail overlap of parallel molecules, in which π–π interactions can occur, is observed. Compound 1 exhibited a cytotoxic effect in all of the evaluated tumoral cell lines and showed a higher cytotoxic effect in colon and breast cancer cell lines than etoposide, which was used as a reference compound.     

Effect of the air humidity on the proton conductivity of some aminobenzenesulfonic acids

Effects of environment conditions (humidity and temperature) on the proton conductivity of aminobenzenesulfonic acids: 2-amino-(orthanilic) acid (I), 3-amino-(metanilic) acid (II), 4-amino-(sulfanilic) acid (III), their general formula NH₂C₆H₄SO₃H, and 3-amino-4-hydroxobenzenesulfonic acid (IV) [NH₂(OH)C₆H₃SO₃H), as well as (for sake of comparison) inorganic aminosulfonic acid [sulphamic acid (NH₂SO₃H)] (V) are studied. All above-listed compounds are zwitter-ions: they contain a fragment NH ₃ ⁺ SO ₃ ^? . The presence of this structural fragment affects the thermal stability of the compounds; according to the mass-spectrometry analysis data, the decomposition of the SO₃-fragment begins at the following temperatures: (I) ?339, (II) ?370, (III) ?320, (IV) ?278, and (V) ?220°C. It is shown that the increase of the environment relative humidity up to 95% results in the increase of the aminobenzenesulfonic acids proton conductivity from 10^?9–10^?8 to 10^?5 S cm^?1; sulphamic acid, to 10^?4 S cm^?1. At that, the amount of adsorbed water does not exceed 0.2 moles per 1 sulfo group in all cases. The conductance activation energy equals 0.2 eV at a relative humidity of 95%.