Evaluation of catalytic activity of imidazolo[1,2-a]pyridine derivatives: oxidation of catechol

A series of heterocyclic compounds possessing imidazolo[1,2-a]pyridine moiety, namely, ethyl 7-methylimidazolo[1,2-a] pyridine-2-carboxylate L1; 2-(3-nitrophenyl)imidazo[1,2-a]pyridine L2; 3-(imidazo[1,2-a]pyridine-2-yl)aniline L3; 2-phenylimidazolo[1,2-a]pyridine-3carbaldehyde L4; and 2-phenylimidazo[1,2-a]pyridine L5 were synthesized. The in situ generated copper (II), iron (II), and zinc (II) complexes of these compounds (L1–L5) were examined for their catalytic activities and were found to be effective catalysts for the oxidation of catechol to o-quinone with the atmospheric oxygen. The present study reveals that the rate of oxidation depends on four parameters: the nature of the ligand, transition metals, ion salts, and the concentration of the complex. The combination L2(Cu(CH ₃ COO) ₂ ) gives the highest rate.     

Imidazo- und Diazino-Anellierungen an das [1]Benzothieno[2,3—d]pyrimidin-System

Derivatives of the following six ring systems were synthesized:

1. 3,10-Dihydro-[1]benzothieno[2,3-d]imidazo[1,5-a]-pyrimidine (I)
2. 6H-[1]Benzothieno[2,3-d]pyrazino[1,2-a]pyrimidine (II)
3. 1,5-Dihydro-[1]benzothieno[2,3-d]imidazo[1,2-a]-pyrimidine (III)
4. 6H-[1]Benzothieno[2,3-d]pyrimido[1,2-a]pyrimidine (IV)
5. 1,5-Dihydro-imidazo[1,2-a]thieno[2,3-d]pyrimidine (V)
6. 4H-Pyrimido[1,2-a]thieno[2,3-d]pyrimidine (VI)

The first four types are new heterocyclic systems. 2-Aminomethyl-5,6,7,8-tetrahydro-[1]benzothieno[2,3-d]pyrimidin-4(3H)-one (5), which was used as intermediate for typesI andII, was synthesized by various methods. TypesIII andIV were prepared from 2-methylthio-5,6,7,8-tetrahydro-[1]-benzothieno[2,3-d]pyrimidin-4(3H)-one via the corresponding 2-benzylamino derivatives, followed by ring closure.     

Synthesis and antiproliferative activity in vitro of new 2-aminobenzimidazole derivatives. Reaction of 2-arylideneaminobenzimidazole with selected nitriles containing active methylene group

A series of pyrimido[1,2-a]benzimidazole and α-cyanocinnamic acid derivatives have been synthesized in the reactions of Schiff bases 2–7 with selected nitriles containing an active methylene group: malononitrile 8–12, cyanoacetamide 13–16, benzyl cyanide 17–21, benzoylacetonitrile 22–24, cyanoacetate methyl ester 25–28 and benzylacetamide 29. The structures 8–29 were confirmed by the results of elementary analysis and their IR, ¹H-, ¹³C-NMR and MS spectra. The products 8–29 of various chemical structure pyrimido[1,2-a] benzimidazole 8–12, 14–16, 17–21, 23–24, 26 and α-cyanocinnamic acid derivatives 13, 22, 25, 27, 28 were obtained, which are of interest for biological studies or which can be substrates for further synthesis. The selected compounds 10, 13, 14, 17, 19, 21, 23–25 and 28 were screened for their antiproliferative activity in vitro against neoplastic and normal cell lines. The most active two compounds were: 2-(o-bromophenylene)-3-cyano-4-phenyl-1,2-dihydropyrimido[1,2-a]benzimidazole (24) and 3-cyano-4-phenyl-2-(2,4-dimethoxyphenyl)-1,2-dihydropyrimido[1,2-a]benzimidazole (23). However, similarly like cisplatin used as the control, they showed no selectivity towards cancer cells, by inhibiting proliferation of normal mouse fibroblasts in similar manner.      

Strukturelle Abwandlungen an Nukleotiden,Nukleosiden und Nukleosidbasen mit β-Acylvinylphosphoniumsalzen

β-Acetylvinyl-triphenylphosphonium bromide1 reacts with CMP to form the 3,N⁴-etheno-derivative {[6-(5′-phosphoribofuranosyl)-2-methyl-5-oxo-imidazo [1.2-c]pyrimidin-3-yl]-methyl}triphenyl-phosphonium bromide (2). Guanine affords mainly the lin. condensation product [(6-methyl-9-oxo-imidazo[1.2-a]-purin-7-yl)-methyl]triphenylphosphonium bromide (3) and the angular tricyclic product [(6-methyl-9-oxo-imidazo[2.1-b]purin-5-yl)-methyl]-triphenylphosphonium bromide (4). For comparison we synthesized the angular condensed heterocycle5, (6.8-dimethyl-9-oxo-imidazo[2.1-b]purin-5-yl)-methyl]triphenylphosphonium bromide, by reaction of 1-methylguanine with1, and the corresponding linear derivative6 [(4.6-dimethyl-9-oxo-imidazo[1.2-a]purin-7-yl)-methyl]-triphenylphosphoniumbromide from 3-methylguanine and1. AHofmann-type degradation of3 with the anion of diethyl malonate led to7, diethyl (6-methyl-9-oxo-imidazo[1.2-a]purin-7-yl)-methylmalonate, a compound whose structure resembles some Y-bases in t-RNA.Wittig reaction of the silylated nucleoside derivative8 a {[2-methyl-5-oxo-6-(2′.3′.5′-tris-trimethylsilyl)-ribofuranosyl-imidazo[1.2-c]pyrimidin-3-yl]methyl}-triphenylphosphonium bromide, with C₆H₅CHO resulted in the 2-methyl-3(ω-styryl)-6[2′.3′.5′-tris-(trimethylsilyl)]ribofuranosyl-imidazo[1.2-c] pyrimidin-5-one (9).     

One-pot microwave-assisted solvent-free synthesis,theoretical and experimental studies on barrier rotation of C–N bond of N-alkenyl-1,2,3-triazoles

The reactions on benzotriazoles continue to happen to reach interesting varieties of their derivatives. This study reports a fast one-pot microwave-assisted solvent-free synthesis of N-alkenyl-1,2,3-benzotriazole (3, 5, and 7) and 1-(2-Alkyloxycarbonyl-vinyl)-1H-[1–3] triazole-4-carboxylic acid methyl ester (8 and 9) derivatives by nucleophilic addition reactions of 1,2,3-benzotriazole (C₆H₅N₃) (1) and 1H-[1–3] triazole-4-carboxylic acid methyl ester (C₄H₄N₃O₂) (1′) with R-propiolates (R = Me, Et; 2 & 4) and phenylacetylene 6 in good yields. The values of activation energy for rotation around C–N bond in the synthesized N-alkenyl-1,2,3-triazole compounds were studied by DFT-B3LYP/6-31G* method.     

Alkoxy substituted benzodithiophene-alt-fluorobenzotriazole copolymer as donor in non-fullerene polymer solar cells

A new benzodithiophene(BDT)-alt-fluorobenzotriazole(FBTA) D-A copolymer J40 was designed and synthesized by introducing 2-octyldodecyloxy side chains on its BDT units, for expanding the family of the BDT- alt-FBTA-based copolymers and investigating the side chain effect on the photovoltaic performance of the polymer in non-fullerene polymer solar cells(PSCs).J40 exhibits complementary absorption spectra and matched electronic energy levels with the n-type organic semiconductor(n-OS)(3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-sindaceno[1,2-b:5,6-b′]dithiophene)(ITIC) acceptor, and was used as polymer donor in the non-fullerene PSCs with ITIC as acceptor. The power conversion efficiency(PCE) of the PSCs based on J40:ITIC(1:1, w/w) with thermal annealing at 120 °C for 10 min reached 6.48% with a higher open-circuit voltage(Voc) of 0.89 V. The high Voc of the PSCs is benefitted from the lower-lying highest occupied molecular orbital(HOMO) energy level of J40. Although the photovoltaic performance of the polymer J40 with alkoxy side chain is lower than that of J60 and J61 with alkylthio-thienyl conjugated side chains, the PCE of6.48% for the J40-based device is still a relatively higher photovoltaic efficiency in the non-fullerene PSCs reported so far. The results indicate that the family of the BDT-alt-FBTA-based D-A copolymers are high performance polymer donor materials for non-fullerene PSCs and the side chain engineering plays an important role in the design of high performance polymer donors in the non-fullerene PSCs.     

Helix-sense-selective radical polymerization of bulky styrenic monomers: chiral induction and liquid crystallinity

Eight chiral vinylterphenyl monomers,(+)-2,5-bis{4′-[(S)-1″-methylpropyloxy]phenyl}styrene(Ia),(+)-2,5-bis{4′-[(S)-2″-methylbutyloxy]phenyl}styrene(Ib),(+)-2,5-bis{4′-[(S)-3″-methylpentyloxy]phenyl}styrene(Ic),(+)-2,5-bis{4′-[(S)-4″-methylhexyloxy]phenyl}styrene(Id),(?)-2,5-bis{4′-[(R)-1″-methylpropyloxy]phenyl}styrene(Ie),(+)-2-{4′-[(S)-1″-methylpropyloxy]phenyl}-5-{4′-[(R)-1″-methylpropyloxy]phenyl}styrene(IIa),(?)-2-{4′-[(R)-1″-methylpropyloxy]phenyl}-5-{4′-[(S)-1″-methylpropyloxy]phenyl}styrene(IIb),and(+)-2-{4′-[(S)-2′′-methylbutyloxy]phenyl}-5-{4′-[(S)-1″-methylpropyloxy]phenyl}styrene(III),were synthesized and radically polymerized.These molecules were designed to further understand long-range chirality transfer in radical polymerization and to possibly tune the chiroptical properties of the polymers by varying the spatial configuration,position,and various combination of the stereogenic centers at the ends of p-terphenyl pendants.The resultant polymers adopted helical conformations with a predominant screw sense.When the stereogenic centers ran away from the terphenyl group as in Ib?d,the corresponding polymers changed the direction of optical rotation in an alternative way and showed no obvious stereomutation upon annealing in tetrahydrofuran.The two stereogenic centers of IIa,IIb,and III acted concertedly in chiral induction,whereas those of Ia and Ie played a counteractive role.The five polymers derived from Ia,Ie,IIa,IIb,and III underwent stereomutation when annealed in tetrahydrofuran.The polymers PIa?e had good thermal stability and high glass transition temperatures(Tgs).They generated liquid crystalline phases at above Tgs that could be kept upon cooling,with the exception of PIe.This result was consistent with the extended helical structures.     

Catalyst-free tandem Michael addition-cyclization reactions in aqueous media for the synthesis of benzimidazo[1,2-a]pyrimidinone derivatives

The catalyst-free reactions of Baylis-Hillman alcohols (1a-i) with 2-aminobenzimidazole (2) in THF-H₂O (1:4) were developed for the convenient and greener synthesis of benzimidazo[1,2-a]pyrimidinone derivatives (3a-i). The pesticidal activities of 3a-i were examined to investigate a new biological activity of the imidazo[1,2-a]pyrimidinone-type compounds.     

Chemie des 5,7-Dihydroxy-2H-thiopyrano[2,3-b]pyridin-4(3H)-ons

Hydrolysis of the 4-alkyliminothiopyrano[2,3-b]pyridinedioles (5) and 4-alkylaminothiopyrano[2,3-b]pyridones (6) resp. with 10% NaOH gives 5,7-dihydroxy-2H-thiopyrano[2,3-b]pyridine-4(3H)-one (7).7 can be obtained in better yield by reaction of 4-dimethylamino-2(1H)-pyridinethione (8) with bistrichlorphenylethylamlonate (2). Aminolysis of7 affords the two isomeric products5 and6. On treatment with hydrazines,7 reacts only to 4-hydrazonoderivatives5. By heating in bromobenzene5d is cyclisized to 1H-5,1,2,6-thiatriaza-acenaphthylen-7-ol (11). On methylation with methyljodide5,6 and7 furnish the 7-methoxyproducts13,14 and12. By heating in 20% NaOH7 is transformed into the 2-thioxo-3-pyridylmethylketone16 A and its tautomer, 2-mercapto-3-pyridylmethylketone16 B. The structures of5,6 and7 are discussed.     

Phosphorus–nitrogen compounds: part 16. Synthesis, stereogenism, anisochronism and the relationship between 31P NMR spectral and crystallographic data of monotopic spiro-crypta phosphazene derivatives

The condensation reactions of N₂O₃-donor type coronands (1–3) with hexachlorocyclotriphosphazatriene, N₃P₃Cl₆, resulted in the formation of spiro-crypta phosphazene derivatives (4–6). These compounds with excess morpholine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD) afford fully substituted morpholino (7 and 10) and 1,4-dioxa-8-azaspiro[4,5]deca (8)-substituted phosphazene derivatives, respectively. Whilst, in the same conditions, the reactions of 4, 5 and 6 with pyrrolidine, morpholine and DASD also produce partially pyrrolidino-substituted geminal (9 and 11), mono-substituted pyrrolidino (12), morpholino (13) and 1,4-dioxa-8-azaspiro[4,5]deca (14) phosphazenes. It has been clearly observed that the chloride replacement reactions of 4, 5 and 6 with pyrrolidine lead to the geminal products. Compounds 7, 8 and 10 are the first examples of anisochronic tetrakis (amino) phosphazenes according to ³¹P NMR data. The structures of 7, 8 and 10–14 have been determined by FTIR, MS, ¹H, ¹³C and ³¹P NMR, DEPT, and HETCOR spectral data. The solid-state structures of 9, 13 and 14 have been examined by X-ray diffraction techniques. The sums of the bond angles around the spiro cyclic nitrogen atoms [344.8(4)° and 347.6(4)°] of 9, indicate that the nitrogen atoms have pyramidal geometries. Thus, the N atoms seem to have stereogenic configurations. Compounds 12–14 also have two stereogenic P-atoms, and they are expected to be in the mixture of enantiomers. The relationships between NPN (α and α′) bond angles and δP_spiro values and the correlation of Δ(P–N) with δP_spiro and Δ(δP) values are presented.     

Copper complexes of two isomeric NS2-macrocycles

Two isomeric NS₂-macrocycles incorporating a xylyl group at ortho (o -L) and meta (m -L) positions were employed and their copper complexes (1?C5) were prepared and structurally characterized. The copper(II) nitrate complexes [Cu(L)(NO₃)₂] (1: L = o -L, 2: L = m -L) for both ligands were isolated. In each case, the copper center is five-coordinated with a distorted square pyramidal geometry. Despite the overall geometrical similarity, 1 and 2 show the different ligand conformation due to the discriminated packing pattern. Reaction of o -L with copper(II) perchlorate afforded complex 3 containing two independent complex cations [Cu(o -L)(H₂O)(DMF)(ClO₄)]⁺ and [Cu(o -L)(H₂O)(DMF)]²⁺; the coordination geometry of the former is a distorted octahedron while the latter shows a distorted square pyramidal arrangement. In the reactions of copper(I) halides (I or Br), o -L gave a mononuclear complex [Cu(o-L)I] (4) with a distorted tetrahedral geometry, while m -L afforded a unique exodentate 2:1 (ligand-to-metal) complex [trans-Br₂Cu(m-L)₂] (5) adopting a trans-type square-planar arrangement.     

New fluorochromatouranylates of alkali metals: Synthesis and structure

Four new fluorochromatouranylates, namely, K[UO₂(CrO₄)F] · 1.5H₂O (I), Rb[UO₂(CrO₄)F] · 1.5H₂O (II), Rb[UO₂(CrO₄)F] · 0.5H₂O (III), and Cs[UO₂(CrO₄)F] · 0.5H₂O (IV), have been synthesized, and their crystallographic characteristics have been determined. All the compounds crystallize in monoclinic system, space group P2₁/c, with the unit cell parameters a = 13.1744(5) Å, b = 9.4598(3) Å, c = 13.0710(4) Å, β = 103.746(1)°, Z = 4, R = 0.0235 (I); a = 13.5902(7) Å, b = 9.5022(4) Å, c = 13.2271(6) Å, β = 102.914(2)°, Z = 4, R = 0.0247 (II); a = 24.7724(8) Å, b = 12.6671(4) Å, c = 9.4464(3) Å, β = 97.661(1)°, Z = 8, R = 0.0448 (III); a = 25.725(1) Å, b = 12.8261(5) Å, c = 9.4929(4) β = 97.208(1)°, Z = 8 (IV). The pairs of compounds I and II and compounds III and IV are isostructural. Crystals of compounds I–III have been subjected to complete X-ray diffraction study. It has been established that the structures of compounds I–III are built of [UO₂(CrO₄)F] _n ^n? layers, which are parallel to the (100) plane and linked into a framework by alkali-metal cations located between layers, together with water molecules. The effect of topological and geometric isomerism on the structural features of 34 known uranyl compounds of the AT³M² crystallochemical group, to which the studied compounds I–III also belong, is discussed.     

Synthesis, structure, and activity evaluation of two silver(I) complexes as Helicobacter pylori urease inhibitors

Two silver(I) compounds, [Ag(R,R-hxn)](C₇H₄BrO₂) · 2H₂O (I) (Chxn = 1,2-diaminocyclohexane) and [Ag(C₅H₆N₂)₂]₂(C₈H₄O₄) · 10H₂O (II), were synthesized and complex I was structurally characterized by X-ray crystallography. Compound I contains a catena-(trans-1,2-diaminocyclohexane) silver polycation ([Ag(Chxn)]_∞) in a roughly linear fashion, while II possesses a linear-type silver monocation. Compounds I and II were evaluated for their inhibitory activities against Helicobacter pylori urease in vitro. Both were found to have strong inhibitory activities against H. pylori urease comparable to that of acetohydroxamic acid.     

Enantioselective Supramolecular Carriers for Nucleoside Drugs. A Thermodynamic and Kinetic Gas Phase Investigation

The enantioselective interactions between chiral tetra-amidic receptors and nucleosides have been investigated by the ESI-IT-MS and ESI-FT-ICR-MS methodologies. Configurational effects on the CID fragmentation of diastereomeric [M ^H ₂ ?H?A]?⁺ aggregates (A?=?2'-deoxycytidine dC, citarabine (ara-C) were found to be mostly offset by isotope effect in [S ^X ₂ ?H?A]?⁺ (X?=?H, D) differently from the results obtained on the analogues (A?=?cytidine C and gemcitabine G). This result points the involvement of two different nucleoside/tetraamide isoforms. The structural differences of the [M ^H ₂ ?H?A]?⁺ (A?=?C and G) complexes vs. the [M ^H ₂ ?H?A]?⁺ (dC and ara-C) ones is fully confirmed by the kinetics of their uptake of the 2-aminobutane enantiomers, measured by FT-ICR mass spectrometry. Indeed, uptake of the 2-aminobutane enantiomers by [M ^H _n ?H?A]?⁺ (n?=?1,2; A?=?dC and ara-C) complexes is reversible, while that by [M ^H _n ?H?A]?⁺ (n?=?1,2; A?=?C and G) is not. The most encouraging result concerning the measured fragmentation and kinetic differences between C and ara-C, that are just epimers, indicates the possibility to subtly modulate the non-covalent drug/receptor interactions, through the electronic properties of the 2'-substituent on the nucleoside furanose ring, and furthermore on its three-dimensional position.     

Triazolo[4′,3′:4,5] [1,3,4]thiadiazolo[2,3-b]quinazolin-6-one

3-Methyl-6H-[1,2,4]triazolo[4′,3′: 4,5] [1,3,4]thiadiazolo[2,3-b]quinazolin-6-one (6) has been synthesized by the condensation of isatoic anhydride (1) with 4-amino-5-mercapto-3-methyl-[1,2,4]triazole (2) and final cyclisation of the intermediate3 with POCl₃ and PCl₃. Alternatively6 could also be synthesized by the condensation of 3-amino-2-mercapto-3H-quinazolin-4-one (7) withN-carbethoxy hydrazine in presence of hydrochloric acid and final cyclisation of the intermediate8 with acetic acid. The structures have been confirmed on the basis of IR, PMR and analytical results.     

First MnIII complexes with tetradentate (N2O2) Schiff bases and tricyanomethanide: synthesis,crystal structure,and magnetic properties

The first Mn^III complexes with Schiff bases and tricyanomethanide-anion were synthesized: [Mn(salen)C(CN)₃(H₂O)] (1), [Mn(5-Brsalen)C(CN)₃(H₂O)] (2), [Mn(salpn)C(CN)₃(H₂O)] (3), [Mn(3-MeOsalen)C(CN)₃(H₂O)] (4), [Mn(5-Brsalen)(MeOH)(H₂O)][C(CN)₃] (5), and [Mn(3-MeOsalpn)(H₂O)₂][C(CN)₃] (6), where SalenH₂ is N,N′-bis(salicylidene)ethylenediamine, 5-BrsalenH₂ is N,N′-bis(5-bromosalicylidene)ethylenediamine, SalpnH₂ is N,N′-bis-(salicylidene)-1,3-diaminopropane, 3-MeOsalenH₂ is N,N′-bis(3-methoxysalicylidene)-ethylenediamine, 3-MeOsalpnH₂ — N,N′-bis(3-methoxysalicylidene)-1,3-diaminopropane. The tricyanomethanide anion in complexes 1–4 acts as a the terminal ligand, whereas in complexes 5 and 6 tricyanomethanide is not coordinated by Mn^III and acts as an out-of-sphere counterion. The structures of complexes 1–4 are characterized by the formation of dimers due to hydrogen bonds between the water molecules and oxygen atoms of the Schiff bases. The Mn...Mn distances inside the dimers are 4.69–5.41 Å. Complex 6 has a zigzag chain structure consisting of the [Mn(3-MeOsalpn)(H₂O)₂]⁺ cations bound by double bridging aqua ligands. The study of the magnetic properties of complexes 1, 3, 4, and 6 showed the existence of antiferromagnetic interactions between the Mn^III ions through the system of hydrogen bonds.     

Synthese von Thiazolo[3,2−a]thieno[2,3−d]pyrimidin-Derivaten

Derivatives of 5H-thiazolo[3.2?a]thieno[2.3?d]pyrimidine(A), 5H-[1]benzothieno[2.3?d]thiazolo[3.2?a]pyrimidine (B), 4H-thiazolo[3.2?a]thieno[3.2?e]pyrimidine (C) and 5H-[1]benzo-thieno[3.2?e]thiazolo[3.2?a]pyrimidine (D) were synthesized by various methods. Similar reactions are leading to derivatives of thieno[2′.3′∶4.5]pyrimido[2.1?b][1.3]thiazine (E) and [1]benzothieno[2′.3′∶4.5]pyrimido[2.1?b][1.3]thiazine (F).C, D, E, andF are new heterocyclic ring systems. Detailed papers will appear soon.     

Anion-directed organized assemblies of protonated pyrazole-based ionic salts

The reactions of 3(5)-(4-methoxyphenyl)-5(3)-phenyl-1H-pyrazole (L ¹ ) with nitric acid and 5-(4-benzyloxyphenyl)-3-(furan-2-yl)-1H-pyrazole(L ² ) with hydrochloric acid produced [HL ¹ · NO₃] (Salt-1) and [HL ² · Cl] (Salt-2). The structures of Salt-1 and Salt-2 were determined by single crystal X-diffraction. In Salt-1, HL ¹ showed [2 + 2] binding of NO₃ ^? ions in the solid state to form dimer architecture with R ₁ ² (4) and R ₄ ⁴ (14) graph sets. An anion directed one-dimensional anion-assisted helical chain with active participation of the chloride ion and protonated pyrazole via N–H···Cl hydrogen bonding in Salt-2. In addition, the protonated HL ² molecules interacted with each other through weak C–H···π interactions resulting in the formation of another one-dimensional helical chain.     

Synthesis, characterization and aggregation behaviour of novel peripherally tetra-substituted octacationic water soluble metal-free and metallophthalocyanines

In this study, a new phthalonitrile derivative 3 bearing 1,3-bis[3(dimethylamino)phenoxy]propan-2-ol 1, metal-free phthalocyanine (Pc) 4, metallophthalocyanines (MPcs) 5–7 and their quaternized derivatives 4a–7a were synthesized. Metal-free Pc 4 was prepared by cyclotetramerization of phthalonitrile derivate 3 and MPcs 5–7 were synthesized by heating 3 with NiCl₂, CoCl₂ and CuCl₂ in n-pentanol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, respectively. Quaternization of the dimethylamino functionality produced quaternized octacationic water soluble metal-free, Ni, Co and Cu Pcs which were soluble in water, DMF, DMSO. The aggregation behaviour of these compounds were investigated in different concentrations of chloroform for metal-free, Ni, Co and Cu Pcs. The effect of solvents on absorption spectra were studied in various organic solvents. The novel compounds were characterized using IR, ¹H-, ¹³C NMR, UV–vis and MS spectral data.     

Polymerization of ethylene by SiO2-supported two-component catalytic systems containing bis(imino)pyridine and bis(imine) ligands

The polymerization of ethylene initiated by SiO₂-supported two-component catalytic systems based on 2,6-bis[1-(2,4-dimethyl-6-cyclohexylphenylimino)ethyl]pyridine iron (II) chloride (I) and 1,2-bis(2-cyclohexyl-4,6-dimethylphenylimino)acenaphthene] nickel bromide (II) was studied. Methylaluminoxane was used as a cocatalyst during support. It was shown that the activity of two-component catalytic systems and the molecular mass and short-chain branching of polyethylene samples depend on the supporting procedure: simultaneous immobilization of components I and II, separate immobilization of components on the support (first I, then II, and vice versa), and the use of a mixture of components I and II immobilized separately on SiO₂.