Grzegorz Schroeder

FTIR, NMR and kinetic studies of proton transfer reactions from nitro-substituted diarylmethanes to N-bases with guanidine character

Abstract Deprotonation of bis(2,4-dinitrophenyl)methane (C-acid 1) and 2,4-dinitrophenyl-2,4,6-trinitrophenylmethane (C-acid 2) by 7-methyl-1,5,7-triazabicyclo[4,4,0]dec-5-ene (MTBD) and 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD) in acetonitrile has been studied using 1 H and 13 C NMR as well as FT-IR spectroscopy. The 1:1 mixtures of N-bases with C-acids form protonated N-bases and products, for which only one respective structure was found. In the case of deprotonated C-acid 1 a symmetrical charge distribution in the phenyl rings was found, whereas for deprotonated C-acid 2 the charge distribution was asymmetrical. The spectral feature was explained as a strong electrostatic interaction between the product and the protonated N-bases. The kinetics of the proton transfer reaction from C-acid 1 and C-acid 2 to MTBD and TBD in acetonitrile are reported. The activation parameters are discussed in two aspects: the steric effect of the basic centre and the delocalization of charge for the carbanion products.

The Schiff base of gossypol with 2-(aminomethyl)-15-crown-5 complexes with monovalent cations studied by MS, 1H NMR, FT-IR and PM5 semiempirical methods

A new Schiff base of gossypol with 2-(aminomethyl)-15-crown-5 [GSCB] was shown to be capable of complexation of monovalent cations. This process of complex formation was studied by electrospray ionization (ESI) mass spectrometry, 1H NMR and FT-IR spectroscopy, as well as by PM5 semiempirical method. It was found that the gossypol Schiff base can form 1 ∶ 1 and 1 ∶ 2 complexes with monovalent cations. With H+, Li+ or Na+ cations the Schiff base preferentially forms 1 ∶ 2 complexes. In the complex with protons they are localised on the N atoms of the Schiff base and the molecule exists in the imine–imine tautomeric form. The 1 ∶ 2 complexes of the Schiff base with Li+ and Na+ cations occur only in the enamine–enamine tautomeric form and the cations are coordinated only by the oxygen atoms of the crowns. The complexes of the Schiff base with K+, Rb+ or Cs+ cations are of 1 ∶ 1 and 1 ∶ 2 type with the oxygen atoms of the crowns, as well as O1H and O1′H groups coordinating the cations. The structures of the complexes are calculated by PM5 semiempirical method and disscussed.

Silicon polypodands: powerful metal cation complexing agents and solid-liquid phase-transfer catalysts of new generation

Abstract Silicon polypodands 5 – 7 are found to be powerful complexing agents of alkali metal salts in low polarity solvents and very efficient catalysts in anion-promoted reactions under solid–liquid PTC conditions. The catalytic activity is comparable with that of the cyclic polyether PHDB18C6 8 .

Basicity, IR spectra and protonation of some proton sponges in acetonitrile

Abstract The pK a values in acetonitrile for three proton sponges, 1,8-bis(dimethylamino)naphthalene (DMAN), 1,8-bis(dimethylaminomethyl)naphthalene (DMAMN) and 1,2-bis(dimethylaminomethyl)benzene (DMAMB), were determined. The relations between basicity and structure, and the infrared behaviour of the intramolecular NHN hydrogen bonds formed via protonation by phenols is discussed. It was found that an increase in the basicity of a sponge favours deprotonation of the phenols, while at the same time the strength of the NHN + hydrogen bond diminishes.

Complexes of Schiff base of gossypol with 5-hydroxy-3- oxapentylamine and some monovalent cations studied by ESI MS as well as PM5 semiempirical methods

Abstract The complexes of the Schiff base of racemic gossypol with 5-hydroxy-3-oxapentylamine (GSBH) with H + and monovalent metal cations were synthesized and studied ESI mass spectrometry and the PM5 semiempirical calculation. The Schiff base studied exists in chloroform solution in the enamine–enamine tautomeric form. After protonation the tautomeric form changes into the imine–imine one. The GSBH molecule form 1:1 complexes with Li + , K + and Rb + cations in which the enamine–enamine tautomeric form is favoured. The structures of the protonated Schiff base and its complex with Li + and K + cation as well as the respective hydrogen bonds within these structures are discussed.

Complexes of Schiff base of gossypol with 5-hydroxy-3-oxapentylamine and Ca2+, Ba2+ or Pb2+ cations studied by NMR, FT-IR, ESI MS as well as PM5 semiempirical methods

Abstract A new Schiff base of gossypol with 5-hydroxy-3-oxapentylamine (GSBH) has been found to complex bivalent metal cations, in particular Ca2+, Ba2+ and Pb2+. This process of complex formation has been studied by ESI mass spectrometry, 1H, 13C NMR and FT-IR spectroscopy as well as by PM5 semiempirical method. It has been established that GSBH forms stable 1:1 complexes with all these cations. In all complexes the Schiff base of gossypol exists as the enamine–enamine tautomer. The Ca2+, Ba2+ cations are coordinated through oxygen atoms from the four hydroxyl groups, and Pb2+ cation additionally also by two oxygen atoms from oxaalkyl chains. The structures of these complexes have been calculated by PM5 semiempirical method and discussed.

Inorganic Esters of Ethylene Glycol as Macrocyclic Ligands

Six different inorganic esters of ethylene glycol: B(OR)3, P(OR)3, OS(OR)2, OP(OR)3, OPH(OR)2 and As(OR)3, where R = CH2CH2OCH3 were obtained. Their structures were studied by multinuclear NMR. These compounds can complex metal cations and behave like macrocyclic ligands. The influence of metal cation complexation on spectra were investigated by 1, 13C, 17O, 11B, 7Li, 87Rb and 31P NMR.

Synthesis of new dendritic antenna-like polypyridine ligands

An efficient synthesis of multidentate polypyridine ligands, 3,5-bis(2,2′-bipyridin-4-ylethynyl)benzoic acid and 3,5-bis(2,5-bis(2-pyridyl)-pyridin-4-ylethynyl)benzoic acid, with potential application in the production of ruthenium dyes for dye-sensitised solar cells was developed. Isolation of intermediate products and final compounds is simple and the yields are very high. The ligands obtained can be used in the synthesis of dendritic analogues of well known and very efficient N3 dye and “black dye”.

Anion-π interactions—interactions between benzo-crown ether metal cation complexes and counter ions

The loss of X· radical from [M + Cu + X]+ ions (copper reduction) has been studied by the so called in-source fragmentation at higher cone voltage (M = crown ether molecule, X− = counter ion, ClO4−, NO3−, Cl−). The loss of X· has been found to be affected by the presence/lack of aromatic ring poor/rich in electrons. Namely, the loss of X· occurs with lower efficiency for the [NO2-B15C5 + Cu + X]+ ions than for the [B15C5 + Cu + X]+ ions, where NO2-B15C5 = 3-nitro-benzo-15-crown-5, B15C5 = benzo-15-crown-5. A reasonable explanation is that Anion-π interactions prevent the loss of X· from the [NO2-B15C5 + Cu + X]+ ions. The presence of the electron-withdrawing NO2 group causes the aromatic ring to be poor in electrons and thus its enhances its interactions with anions. For the ion containing the aromatic ring enriched in electrons, namely [NH2-B15C5 + Cu + ClO4]+ where NH2-B15C5 = 3-amino-benzo-15-crown-5, the opposite situation has been observed. Because of Anion-π repulsion the loss of X· radical proceeds more readily for [NH2-B15C5 + Cu + X]+ than for [B15C5 + Cu + X]+. Iron reduction has also been found to be affected by Anion-π interactions. Namely, the loss of CH3O· radical from the ion [B15C5 + Fe + NO3 + CH3O]+ proceeds more readily than from [NO2−B15C5 + Fe + NO3 + CH3O]+.

STUDIES OF COMPLEXATION OF METAL CATIONS BY TRIS(3,6-DIOXAHEPTYL)AMINE IN SOLUTION

Abstract The complexation of some cations (Zn 2+ , Fe 2+ , Fe 3+ , Ni 2+ , Cu 2+ , Co 2+ , Pb 2+ , Na + , Li + , Mn 2+ , Cd 2+ , K + , Mg 2+ , Cr 3+ ) by tris(3,6-dioxaheptyl)amine in various solvents was studied by the thin layer chromatography, liquid secondary ion mass spectra, FT-IR and 13 C NMR spectroscopies as well as kinetic methods. In this article, the structure of the complexes is discussed.