Petra Bombicz

Thermal decomposition of thiourea complexes of Cu(I), Zn(II), and Sn(II) chlorides as precursors for the spray pyrolysis deposition of sulfide thin films

Abstract Comparative study on thermal decomposition of four thiourea–metal complexes, solid precursors for spray pyrolysis deposition (SPD) methods, had been carried out by using thermoanalytical and X-ray diffraction (XRD) methods in combination. [Cu2(tu)6]Cl2·2H2O (1), ZnCl2(tu)2 (2), Sn2Cl4(tu)5·2H2O (3), and SnCl2(tu) (4) prepared from aqueous thiourea (tu) solutions, had been decomposed in a simultaneous thermogravimetric/differential thermoanalytical (TG/DTA) apparatus, while XRD phase analysis of solid residues obtained at various temperatures had been performed. In static air, a main degradation step between 200°C and 300°C led to the formation of Cu9S5 (digenite), ZnS (zinc blende), and SnS2 (berndtite), respectively. Unfortunately, some chemical species with low volatility still remained in condensed phase, while above 400°C, primary oxidation products of sulfides such as Cu2O(SO4) (dolerophanite), ZnO, and SnO2 also occurred. Nevertheless, intermittent spray pyrolysis depositions of Cu2SnS3 and Cu2ZnSnS4 films from some thiourea solutions with Cu(I), Zn(II), and Sn(II) onto glass substrates, with temperature ranging between 225°C and 300°C, were successful.

Supramolecular interactions in the solid state

Supramolecular interactions in the solid state are discussed in the context of crystal engineering. Specific topics include halogen bonding, ambient and non-ambient conditions, isostructurality and polymorphism, and kinetic assembly of coordination polymers.

Thermal, FTIR and XRD study on some 1:1 molecular compounds of theophylline

Thermal stability and structural features of three newly synthesized 1:1 lattice compounds of theophylline (th) with ethylenediamine carbamate (enCO2), 1,10-phenanthroline (phen), and 5-sulfosalicylic acid (sa-5-SO3H) have been studied in comparison with those of the theophylline compounds with ethanolamine (ea) and salicylic acid (sa). Simultaneous TG-DTA measurements, FTIR spectroscopy and X-ray diffraction have been carried out to get information on the various structural units of these solid inclusions, especially on the actual form (molecule, anion or cation) of theophylline moieties built in. Theophyllinate and theophyllinium ions have been found in the ethanolammonium-theophyllinate (1:1) (1, eaH+⋅th-) and the theophyllinium salicylic acid 5-sulfonate monohydrate (1:1:1), (5, thH+⋅saSO−3⋅H2O), respectively. Whilst the 1:1 complexes with 1,10-phenanthroline (2, th⋅phen), ethylenediamine carbamate (3, th⋅enCO2), and salicylic acid (4, th⋅sa) contain neutral theophylline moieties associated with H-bonds. In compound (3) the zwitterion of N-(2-ammonium-ethyl)carbamate (NH3+-CH2-CH2-NH-CO-2) is present.

Inclusion compounds containing a drug: structure and thermal stability of the first clathrates of nitrazepam and isothiocyanato ethanol complexes of Co(II) and Ni(II)

Abstract Syntheses, crystal structures and comparative analytical investigations on the first two inclusion compounds of an antiepileptic drug, nitrazepam (1,3-dihydro-7-nitro-5-phenyl-2H-1,4-benzodiazepin-2-one) are reported. The biologically active molecule forms isostructural clathrates with diaquadiethanolbis(isothiocyanato) complexes of both cobalt(II) and nickel(II) in molar ratios of 1:2 [M(NCS)2(C2H5OH)2(H2O)2]·2C15H11N3O3 (M=Co2+, 1, and M=Ni2+, 2). Detailed analyses of the structures, the secondary interactions, the neutral drug conformations, the FTIR spectra and thermal stabilities of the clathrates, in comparison with those of the crystalline nitrazepam, have been carried out. In the crystal structures there are only host–guest hydrogen bonds of O⋯H, N⋯H and S⋯H type. Owing to the comparable size of the two constituents neither host–host nor guest–guest secondary interactions occur. In the first thermal decomposition step a parallel release of ethanol and water was observed by simultaneous thermogravimetric and differential thermal analysis measurements. This indicates that some bonds of the metal complex unit and the host–guest secondary interactions in 1 and 2 are weaker than interactions in the pure drug. If an easy release of ethanol and water occurs during dissolution of 1 and 2, it might result in an improved bioavailability of the drug, which is soluble only in aqueous ethanol.

Comparison of theophyllinato Cu(II) complexes of ethanolamine and diethanolamine. Part 2. Structure and thermal study of the dimeric complex with diethanolamine

Abstract There is now much evidence that anticancer drugs exert biological action by preferred binding of a transition metal to the N7 sites of the guanine residues of DNA. In our series of theophyllinato copper(II) complexes containing amine ligands, the structural effect of changing from ethanolamine to diethanolamine is examined. A new mixed ligand copper(II) complex, bis(μ-2-(2-hydroxyethyl)aminoethanolato-O,N,O′)bis(theophyllinato-N7)dicopper(II) (C22H34N10O8Cu2) (1) has been synthesized as model compound from aqueous solutions of CuSO4, theophylline, and diethanolamine (dea). Its distinct Me2L2L′2 structure has been determined by single crystal X-ray diffraction. The centrosymmetric binuclear complex contains two strongly distorted square pyramidally (or pseudooctahedrally) coordinated copper ions bound together by two alkoxo-bridges. The bridging O is a deprotonated oxygen of the monoalcoholate formed from diethanolamine. Both of the theophyllinate anions take part in N7/O6 chelation in the complex 1, while only one of the theophyllinate anions is able to perform it in the mononuclear complex (SPY-5-12)-(2-aminoethanol-N)(2-aminoethanol-N,O)bis(theophyllinato-N7)copper(II) dihydrate (2). The two copper(II) centres in 1 are found to be antiferromagnetically coupled. The combined thermogravimetric and evolved gas detection shows that the tridentate alcoholate anions are fragmented and evolved between 125 and 275°C, whilst the degradation of theophyllinate anions begins at 350°C. Structural, spectroscopic and thermal comparison to the previously published analogous monoethanolamine Cu(II) complex (2) is presented.

Structure and thermal behaviour of (SPY-5-12)-(2-aminoethanol-N) (2-aminoethanol-N,O)-bis(theophyllinato)copper(II)dihydrate: a model for DNA-metal interactions

Abstract The title compound (1) is obtained by mixing aqueous 2-aminoethanol solutions of theophylline and copper(II) salt. According to the single crystal data the Cu2+, ion is pentacoordinated and located in a slightly distorted square pyramidal configuration. Four short CuN bonds to two N(7) of the theophyllinate anions and to two nitrogen atoms of a monodentate and a bidentate 2-aminoethanol ligands are almost in the plane, while a longer CuO bond to oxygen of the bidentate 2-aminoethanol is in the apex at distance 2.350(8) A. When heated in air or in an inert atmosphere, 1 undergoes a five-step decomposition process studied by TG, DSC and evolved gas detection (EGD). The solid intermediates of the thermal decomposition were detected by FTIR and powder X-ray diffraction. First the water molecules then the mono- and bidentate 2-aminoethanol ligands are released in the order of their binding energy, showing a strong structure-stability correlation. Afterwards chemical degradation of theophyllinato ligands occurs and is accompanied in air by an intense oxidation process resulting in CuO formation.

Fine tuning of crystal architecture by intermolecular interactions: synthon engineering

There has been a long time effort to influence or favourably fine tune structural properties by introduction of substituents or guest molecules of different sizes, shapes and chemical composition to consequently alter physico-chemical properties of the respective crystals. These attempts require the recognition, understanding and application of intermolecular interactions, crystallographic and, in case of occurrence, non-crystallographic symmetries. It brings us to the field of crystal engineering, which aims to produce new substances with required properties based on the knowledge of the structural properties of already characterised solids. A series of calixarene crystal structures are presented where the crystal packing is determined by spatial or by electrostatic effects. A series of laterally substituted calixarenes where both steric requirements and electrostatic forces play a role in the crystal architecture shows how the supramolecular synthon can be engineered.

Conformational behaviour and first crystal structures of a calix[4]arene featuring a laterally positioned carboxylic acid function in unsolvated and solvent-complexed forms

A detailed conformational analysis of a rarely investigated type of compound, a laterally monosubstituted calix[4]arene (1, which has a carboxylic acid function in the lateral position), is reported. 2D solution NMR techniques at various temperatures and in different solvents have been used, showing interesting aggregation behaviour for the different conformers. The first illustrations of crystal structures of this compound type are given, including the unsolvated carboxylic calix[4]arene and two mixed solvent complexes containing EtOH–H2O and EtOH–THF, respectively. Isostructurality calculations have been carried out, allowing detailed comparison of the investigated structures, and an unusual conformational chirality isomerism of the calixarene molecule is demonstrated.

Utilization of Copper-Catalyzed Carboarylation–Ring Closure for the Synthesis of New Oxazoline Derivatives

A copper-catalyzed carboarylation-ring-closure strategy was used for the modular synthesis of oxazolines via the reaction of 1-aryl- and 1-alkylpropargylamides and diaryliodonium salts. The novel approach enables the efficient, modular synthesis of oxazoline derivatives bearing fully substituted exo double bonds.

Halogen···halogen versus OH···O supramolecular interactions in the crystal structures of a series of halogen and methyl substituted cis-9,10-diphenyl-9,10-dihydroanthracene-9,10-diols1

Abstract The crystal structures of four p-phenyl-substituted cis-9,10-diphenyl-9,10-dihydroanthracene-9,10-diols, carrying chloro- (1), bromo- (2), iodo- (3) and methyl substituents (4), respectively (with 2 being a previously described compound), have been studied in order to compare the effects of these substituents on the crystalline architecture. Ordinary O–H···O hydrogen bonds govern the packing of the methyl-substituted molecules in 4, whereas interhalogen interactions in competition with conventional hydrogen bonds direct the crystalline arrangement of the halogenated homologues 1–3, yielding somewhat lower symmetry and lower packing coefficient for the latter crystals. All short (Cl···Cl