Iwona Kowalczyk

Strong hydrogen bonds in 1:1 and 2:1 complexes of pyridine betaine with strong acids

Abstract The crystal structure of bis(pyridine betaine) hydrochloride- d 1 monohydrate- d 2 has been determined by X-ray analysis. The carboxylate groups of a pair of pyridine betaine molecules are bridged by a deuteron to form a centro-symmetric dimer featuring a very strong hydrogen bond of length 2.444(4) A. The geometric mass effect (Δ R ≈ 0.008 A) is well within the range observed for this type of hydrogen bond. The FT-IR spectra of polycrystalline 1:1 and 2:1 complexes of pyridine betaine with HNO 3 , HCl, HBr, HI, HO 3 SCF 3 , HClO 4 , HBF 4 , and H 2 SO 4 have been investigated in the 4000–200 cm −1 range. In the 1:1 complexes a proton is transferred from the acid to the betaine molecule, C 5 H 5 N + CH 2 COOH · A − , and both the νOH and νCO frequencies vary with the proton acceptor properties of the anion. The spectra of the 2:1 complexes show broad and intense O · H · O stretching absorptions in the 1500–200 cm −1 range which are slightly affected by the anion and are similar to that for type A acid salts of carboxylic acids. The skeletal vibrations of the betaine residue were identified by second derivative spectroscopy. Evidence based on the νCO vibration and deuteration suggests that the hydrogen bonds in [C 5 H 5 NCH 2 COO · H · OOCCH 2 NC 5 H 5 ] + A − are described by single minimum potentials; ν H = 940 cm −1 , ν H /ν D = 1.2. As betaines are widely distributed in plants and animal tissue and form complexes with strong hydrogen bonds, such bonds should be formed in biological systems.

Synthesis, Molecular Structure, Spectral Properties and Antifungal Activity of Polymethylene-α,ω-bis(N,N-dimethyl-N- dodecyloammonium bromides)

Hexamethylene-1,6-bis-(N,N-dimethyl-N-dodecylammonium bromide) (1), pentamethylene-1,5-bis(N,N-dimethyl-N-dodecylammonium bromide) (2), tetramethylene-1,4-bis(N,N-dimethyl-N-dodecylammonium bromide) (3), trimethylene-1,3-bis(N,N-dimethyl-N-dodecylammonium bromide) (4) and ethylene-1,2-bis(N,N-dimethyl-N-dodecylammonium bromide) (5) have been obtained and characterized by FTIR and NMR spectroscopy. DFT calculations have also been carried out. The optimized bond lengths, bond angles and torsion angles calculated by Hartree-Fock/3-21G(d,p) approach have been presented. MIC values for A. niger, P. chrysogenum, C. albicans have been determined and the relationship between MIC and spacer length has been discussed.

Synthesis, Spectroscopic and Theoretical Studies of New Quasi-Podands from Bile Acid Derivatives Linked by 1,2,3-Triazole Rings

A novel method for the synthesis of bile acid derivatives has been developed using “click chemistry”. Intermolecular 1,3-dipolar cycloaddition of the propargyl ester of bile acids and azide groups of 1,3,5-tris(azidomethyl)benzene gave a new quasi-podands with 1,2,3-triazole rings. The structures of the products were confirmed by spectral (1H-NMR, 13C-NMR, and FT-IR) analysis, mass spectrometry and PM5 semiempirical methods. Estimation of the pharmacotherapeutic potential has been accomplished for synthesized compounds on the basis of Prediction of Activity Spectra for Substances (PASS).

Study of cyclic quaternary ammonium bromides by B3LYP calculations, NMR and FTIR spectroscopies.

N,N-dioctyl-azepanium, -piperidinium and -pyrrolidinium bromides 1-3, have been obtained and characterized by FTIR and NMR spectroscopy. DFT calculations have also been carried out. The optimized bond lengths, bond angles and torsion angles calculated by B3LYP/6-31G(d,p) approach have been presented. Both FTIR and Raman spectra of 1-3 are consistent with the calculated structures in the gas phase. The screening constants for 13C and 1H atoms have been calculated by the GIAO/B3LYP/6-31G(d,p) approach and analyzed. Linear correlations between the experimental 1H and 13C chemical shifts and the computed screening constants confirm the optimized geometry.

Synthesis, molecular structure and spectral properties of quaternary ammonium derivatives of 1,1-dimethyl-1,3-propylenediamine.

1,1-Dimethyl-3-oxo-1,4-diazepan-1-ium chloride (1) and 1,1-dimethyl-1-carboxymethyl-3-aminopropyl ammonium hydrochloride (2) have been obtained by the reactions of 1,1-dimethyl-1,3-propylenediamine with ethyl chloroacetate and chloroacetic acid, respectively. The products have been characterized by FTIR, Raman and NMR spectroscopy. B3LYP calculations have also been carried out. The screening constants for 13C- and 1H- atoms have been calculated by the GIAO/B3LYP/6-31G(d,p) approach and analyzed. The FTIR and NMR spectra of the investigated compounds 1 and 2 are in excellent agreement with the structures optimized by Density Functional Theory (DFT) calculations.

Structure, conformation and hydrogen bonding of some pyridiniumpropionate complexes

Abstract Crystals of N -(2-carboxyethyl)pyridinium sulphate, [C 5 H 5 N + CH 2 CH 2 COOH] 2 SO 2− 4 , are orthorhombic, Pna 2 1 , a = 15.392(1), b = 16.672(1), c = 7.0770(4) A , Z = 4. The SO 2− 4 anion forms two hydrogen bonds with two COOH groups, the O···O distances being 2.510(3) and 2.570(3) A, and the OHO angles 142(5) and 173(4)°. The gauche conformation of the N + (1)C(7)C(8)(9) linker fragment is stabilized mainly by Coulombic attractions between the charged nitrogen and oxygen atoms. Structures of isolated molecules of N -(2-carboxyethyl)pyridinium monohydrate, N -(2-carboxyethyl)pyridinium chloride, N -(2-carboxyethyl)-pyridinium cation, N -(2-carboxyethyl)pyridinium sulphate and N -(2-carboxyethyl)trimethylammonium bromide optimized using the PM3 and DFT methods are significantly different from those observed in the crystals because of electrostatic interactions in the crystal lattice. In the crystal, the positively charged N + groups interact both with their “own” carboxyl groups (intramolecular compensation of charge) and with neighbouring molecules (intermolecular charge compensation), whereas in the gas phase only intramolecular charge compensation is possible. FTIR spectra show that an additional methylene unit between the charged groups increases the symmetry of the COO group and reduces its proton-acceptor properties, without affecting the hydrogen bonds in compounds N -(2-carboxyethyl)pyridinium hemihydrobromide, N -(2-carboxyethyl)pyridinium hemitetrafluoroborate, N -(2-carboxyethyl)pyridinium hemiperchlorate and N -(2-carboxyethyl)pyridinium heminitrate (2:1 homoconjugated complexes).

Synthesis, Spectroscopic and Semiempirical Studies of New Quaternary Alkylammonium Conjugates of Sterols

New quaternary alkylammonium conjugates of steroids were obtained by two step reaction of sterols (ergosterol, cholesterol, dihydrocholesterol) with bromoacetic acid bromide, followed by bimolecular nucleophilic substitution with a long chain tertiary alkylamine. The structures of products were confirmed by spectral (1H-NMR, 13C-NMR, and FT-IR) analysis, mass spectrometry and PM5 semiempirical methods. The pharmacotherapeutic potential of synthesized compounds has been estimated on the basis of Prediction of Activity Spectra for Substances (PASS).

Synthesis, Spectroscopic and Theoretical Studies of New Quaternary N,N-Dimethyl-3-phthalimidopropylammonium Conjugates of Sterols and Bile Acids

New quaternary 3-phthalimidopropylammonium conjugates of steroids were obtained by reaction of sterols (ergosterol, cholesterol, cholestanol) and bile acids (lithocholic, deoxycholic, cholic) with bromoacetic acid bromide to give sterol 3β-bromoacetates and bile acid 3α-bromoacetates, respectively. These intermediates were subjected to nuclephilic substitution with N,N-dimethyl-3-phthalimidopropylamine to give the final quaternary ammonium salts. The structures of products were confirmed by spectral (1H-NMR, 13C-NMR, and FT-IR) analysis, mass spectrometry (ESI-MS, MALDI) as well as PM5 semiempirical methods and B3LYP ab initio methods. Estimation of the pharmacotherapeutic potential has been accomplished for synthesized compounds on the basis of Prediction of Activity Spectra for Substances (PASS).

Rare stoichiometry of carboxyl–carboxylate benzbetaine complexes: in vitro versus in silico

The first betaine–mineral acid complex of 3:2 stoichiometry, as well as a 1:1 complex common for this class of compounds, has been obtained. Crystalline [di-(3-trimethylammonium-benzoic acid)–(3-trimethylammonium-benzoate)]diiodide (1) is the only betaine–mineral acid 3:2 complex obtained so far. Two concomitant polymorphs of this 3:2 complex, 1-I and 1-II, have been isolated and characterized by X-ray diffraction and FTIR spectroscopy. Polymorphs 1-I, of monoclinic space group P21/c, and 1-II, of orthorhombic space group Pccn, have very similar lattices and aggregates of one zwitterionic molecule and two cations O–H⋯O bonded into a 3-membered catemeric carboxyl–carboxylate–carboxyl interval, but polymorph 1-II dissolves better in methanol than 1-I. Alternative hypothetical aggregates of 3-trimethylammonium-benzoate hydroiodide 1:1, 2:1 and 3:2 complexes optimized at the B3LYP/6-31G(d,p) level of theory suggest that the betaine-to-acid 3:2 stoichiometry is favoured at the stage of small cluster aggregation and not due to the complex crystal packing preferences.

Crystal and single molecule structures of N-(carbomethoxymethyl)-pyridinium perchlorate

Abstract The crystal structure of N -(carbomethoxymethyl)-pyridinium perchlorate, C 5 H 5 N + CH 2 COOCH 3 ·ClO 4 − ( 1 ), was determined by X-ray diffraction as triclinic, space group P 1 with a=7.887(2) A , b=9.891(2) A , c=15.560(3) A , α =100.09(3)°, β =100.80(3)°, γ =109.71(3)° and Z =4. Two symmetry-independent ionic pairs denoted as 1a and 1b are present in the crystal. The angles between the planes through the pyridine ring and O(1), O(2), C(8) and C(7) atoms are 65.5(2)° in 1a and 52.9(3)° in 1b . The B3LYP and PM3 data suggest that the conformers studied have a flat energy region around the energy minima and the interconversion between conformers can occur by displacement of the ClO 4 − anion relative to the cation. Both FTIR and Raman spectra are consistent with the observed structure.