Functional polymers. XIX. Biuret oligomers and polymers of biologically active primary aliphatic amines

Biuret oligomers and polymers from primary aliphatic amines and aromatic or aliphatic diisocyanates have been synthesized. To demonstrate the feasibility of the synthesis of polybiurets, aliphatic primary amines with n-propyl, n-hexyl, n-octyl, and n-dodecyl groups have been incorporated. For the synthesis of biuret oligomers of biologically active primary aliphatic amines [8-(4-amino-1-methylbutylamino)-6-methoxyquinoline] (primaquine) and adamantanamine were selected. Primaquine was also incorporated into polyepichlorohydrin by nucleophilic substitution of the chlorine of the chloromethyl group by the primary aliphatic amino group of primaquine. The structure of the biuret polymers was established by elemental analysis, and by infrared ¹H- and ¹³C-NMR spectroscopic characterization. Several attempts to use primaquine as a diamine for the formation of condensation polymers, including reaction of primaquine with sebacoyl chloride (to form polyamides), or with diisocyanates (to form polyureas) were unsuccessful.     

Synthesis and properties of an open-chain polyimide from benzyloxyamine and terephthaloyl chloride

A procedure for synthesizing an open-chain polyimide has been developed. O-Substituted hydroxylamines were found to behave as difunctional nucleophiles in acylation under appropriate conditions, and thus the reaction of equimolar amounts of benzyloxyamine and terephthaloyl chloride gave rise to the corresponding novel type of polyimide, an open-chain polyimide. The results of polymerization under various conditions indicated the reaction to proceed efficiently in N, N-dimethylacetamide in the presence of an acid acceptor system composed of double the molar quantity of triethylamine and the molar quantity of pyridine to give the polyimide with a high molecular weight. In contrast to the conventional polyimides having cyclic imide structures, the resulting open-chain polyimide exhibited remarkable solubility in common organic solvents and a low glass transition temperature.     

The Extractive-Spectrophotometric Determination of Iron(III) As a Mixed-Ligand Complex with N-Hydroxy-N,N′DI-p-Tolyl-p-Toluamidine and Thiocyanate

The extractive-photometric determination or iron(III) as a mixed-ligand complex with N -hydroxy-N, N′ -di-p -tolyl-p -toluamidine (HDTTA) and thiocyanate is described. The orange-red Waterinsoluble 1:1:2 (metal: HDTTA: SCN^?) ternary complex formed in 0.1–0.6 M hydrochloric acid solutions is quantitatively extractable into benzene. The wavelength of maximum absorption, molar absorptivity and sensitivity of the colour system are 460nm, 12000 l. mole^?1 cm^?1 and 0.0046 μg Fe/cm ²respectively. The influence or foreign ions on the determination of iron has been studied. This method has also been applied to determine the iron content of several alloys.     

Synthesis and Characterization of Oxybis(Diacetoxyborane) Derivatives of Bifunctional Tridentate Aldimines

The reactions of oxybis(diacetoxyborane) with the aldimines, N-(2-hydroxyethyl) salicylaldimine N-(2-hydroxy-1-propyl) salicylaldimine, N-(3-hydroxy-1-propyl) salicylaldimine, N-(o-hydroxyphenyl) salicylaldimine. N-(m-hydroxyphenyl) salicylaldimine, N(2-hydroxyethyl)-2-hydroxy-1-naphthaldimine and N(2-hydroxy-1-propyl) 2-hydroxy-1-naphthaldimine have been carried out in 1: 1 and 1: 2 molar ratios. All the compounds except those derived from N-(3-hydroxy-1-propyl) salicylaldimine have been found to be sparingly soluble in benzene and nonelectrolytes in anhydrous DMF. The newly synthesized derivatives have been characterized by elemental analysis, molecular weight determinations and infrared, proton magnetic resonance, ultraviolet, visible and ¹¹B nuclear magnetic resonance spectral studies.     

New Stable Complexes of Au(III) with Biuret: X-ray Structure of cis-[Au(Biu)Br2]PPh4 and Ab Initio Investigation of cis-[Au(Biu)X2]−

Two anionic complexes of Au(III) with the bioligand biuret, cis-[Au(Biu)X₂]^? (BiuH₂=biuret, X=Cl, Br), have been synthesized and characterized. The molecular structure of cis-[Au(Biu)Br₂]PPh₄ has been determined by X-ray diffraction analysis. The complex anion has square-planar geometry with one deprotonated biuret dianion coordinated bidentately to the metal center via the terminal amino nitrogen atoms and two bromide ions in cis positions. There are no significant intermolecular Au-Au interactions in the solid state. Ab initio calculations of the geometric structure at different computational levels for biuret and both anionic complexes as well an IR study of the structures obtained are performed.     

Iron(III)5(2′-hydroxyphenyl)-3-(4-X-phenyl)pyrazolinates and their addition complexes with N,P donor ligands: synthesis,spectral and antimicrobial investigations

Iron(III)5(2′-hydroxyphenyl)-3-(4-X-phenyl)pyrazolinates of the type (C₁₅H₁₂N₂OX)₃Fe [where X =–H,–Cl,–CH₃,–OCH₃] have been synthesized by reaction of anhydrous FeCl₃ with the sodium salts of pyrazoline in 1 : 3 molar ratio. Their addition complexes with N and P donor ligands [2,2′-bipyridine, 1,10-phenanthroline and triphenylphosphine] were prepared in 1:1 molar ratio. These newly synthesized derivatives have been characterized using elemental analysis (C, H, N and Fe), molecular weight measurement, magnetic moment data, FAB mass, ³¹P NMR and Mössbauer spectral data. The complexes have been examined for crystalline/amorphous nature through XRD; all complexes are amorphous. Octahedral geometry around iron(III) confirms the presence of three bidentate pyrazoline ligands in iron(III)5(2′-hydroxyphenyl)-3-(4-X-phenyl)pyrazolinates. In addition complexes pyrazoline is monodentate. The bidentate and monodentate behavior of pyrazoline ligands was confirmed by IR spectral data. All the complexes were tested for their in-vitro antimicrobial activity. The metal complexes and their adducts exhibit better antibacterial and antifungal activity than the pyrazolines.     

Synthesis,Spectroscopic Characterization,and Antifungal Activity of Some Mixed Ligand Complexes of Zn(II), Cd(II), and Hg(II)

A series of new mixed ligand complexes of Zn(II), Cd(II), and Hg(II) with citronellal thiosemicarbazone [3,7-dimethyl-6-octene-1-a1 thiosemicarbazone (LH)] and N-phthaloyl amino acids (AH) have been synthesized by the reaction of metal(II) chloride with ligands citronellal thiosemicarbazone (DOTSC) and N-phthaloyl glycine [1,3-dihydro-1,3-dioxo-2H-isoindole-2-acetic acid (A₁H)] or N-phthaloyl alanine [1,3-dihydro-1,3-dioxo-α(methyl)-2H-isoindole-2-acetic acid (A₂H)] in 1:1:1 molar ratio in dry refluxing ethanol. All the complexes have been characterized by elemental analyses, molar conductance measurement, molecular weight measurement, IR, and multinuclear NMR (¹H and ¹³C{¹H}) spectral studies. IR, ¹H, and ¹³C{¹H} NMR spectral studies suggest the involvement of azomethine-N, thiol-S atoms of the thiosemicarbazone moiety and both carboxylate-O of N-phthaloyl amino acid moiety in coordination with central metal(II) ion, and four coordinated geometries have been assigned to these complexes. The free ligands and metal complexes have been screened for their antifungal activity against two fungal strains, Fusarium moniliformae and Macrophomina phaseolina, using the the radial growth method. The results of antifungal activity show that metal complexes show enhanced higher activity than the free ligands.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Benzocyclobutene in polymer synthesis. III. Heat-resistant thermosets based on Diels–Alder polymerization of a bisbenzocyclobutene and a bismaleimide

Several compatible mixtures of 2,2-bis[4-(N-4-benzocyclobutenyl) phthalimid-4-phenyl]hexafluoropropane (BCB) and 1,1′-(methylene di-4,1-phenylene)bismaleimide (BMI) were prepared according to the molar ratios (BCB : BMI): 1 : 1; 1 : 1.5; 1 : 3; 1.5 : 1. Complete compatibility of the mixtures was evidenced by a single initial T_g. All mixtures showed relatively low initial T_g's (61–70°C) and characteristic polymerization exotherms of benzocyclobutene-based systems (onset: 221–225°C; maximum: 257–259°C), providing an excellent processing window (ca. 155°C). The cured sample of the mixtures, pure BCB and BMI (250°C; N₂; 8 h) were subjected to comparative isothermal gravimetric analysis (ITGA). After 200 h at 650°F (343°C) in circulating air, the cured BMI sample retained only 3% of its original weight, whereas the mixtures of BCB and BMI exhibited thermo-oxidative stabilities similar to BCB (13–15% weight loss). A model compound was synthesized from the intimate mixture of N-phenylmaleimide and N-benzocyclobutenyl phthalimide in 63% yield. The ITGA results and isolation of the model Diels–Alder adduct render strong support to the conviction that Diels–Alder polymerization is indeed the predominant curing process in the BCB/BMI system.     

Complexation of rhodium(II) tetracarboxylates with aliphatic diamines in solution: 1H and 13C NMR and DFT investigations

The complexation of rhodium(II) tetraacetate, tetrakistrifluoroaceate and tetrakisoctanoate with a set of diamines (ethane‐1,diamine, propane‐1,3‐diamine and nonane‐1,9‐diamine) and their N,N′‐dimethyl and N,N,N′,N′‐tetramethyl derivatives in chloroform solution has been investigated by ¹H and ¹³C NMR spectroscopy and density functional theory (DFT) modelling. A combination of two bifunctional reagents, diamines and rhodium(II) tetracarboxylates, yielded insoluble coordination polymers as main products of complexation and various adducts in the solution, being in equilibrium with insoluble material. All diamines initially formed the 2 : 1 (blue), (1 : 1)_n oligomeric (red) and 1 : 2 (red) axial adducts in solution, depending on the reagents' molar ratio. Adducts of primary and secondary diamines decomposed in the presence of ligand excess, the former via unstable equatorial complexes. The complexation of secondary diamines slowed down the inversion at nitrogen atoms in NH(CH₃) functional groups and resulted in the formation of nitrogenous stereogenic centres, detectable by NMR. Axial adducts of tertiary diamines appeared to be relatively stable. The presence of long aliphatic chains in molecules (adducts of nonane‐1,9‐diamines or rhodium(II) tetrakisoctanoate) increased adduct solubility. Hypothetical structures of the equatorial adduct of rhodium(II) tetraacetate with ethane‐1,2‐diamine and their NMR parameters were explored by means of DFT calculations. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis,spectroscopic investigations,and biological activity of metal complexes of N-benzoylthiosemicarbazide

N-Benzoylthiosemicarbazide, HL, was obtained by fusion of benzoylhydrazide and ammonium thiocyanate. Reactions of HL with cobalt(II), nickel(II), copper(II), zinc(II), iron(III), cadmium(II), oxovanadium(IV), and dioxouranium(VI) in 1 : 1 molar ratio yield the corresponding complexes. The N-benzoylthiosemicarbazide may act as a neutral or monobasic bidentate ligand coordinated through NS or NO sites. The structures of the HL ligand and its complexes were identified by elemental analysis, infrared, electronic, mass, ¹H-NMR, and ESR spectra as well as magnetic susceptibility and molar conductivity measurements. Different geometries were obtained for the metal complexes. The ligand and its metal complexes were investigated for antibacterial and antifungal properties. Two Gram-positive bacteria, Staphylococcus aureus and Streptococcus pyogenes, two Gram-negative, bacteria, Pseudomonas fluorescens and Pseudomonas phaseolicola and two fungi, Fusarium oxysporum and Aspergillus fumigatus, were used in this study. The metal complexes were more effective than the free ligand.     

Application of selective 1 : 2 addition of ketene N,N-acetal and isocyanates to novel polyamide syntheses

1,1-Bis(dimethylamino)ethylene (ketene N,N-acetal) (1) reacted with isocyanates to give either 1 : 1 adduct 3,3-bis(dimethylamino)acrylamides (3) or 1 : 2 adduct bis(dimethylamino)methylenemalonamides (4), depending on the amount of the charged isocyanate. 3 was obtained selectively in the case of isocyanate/1 = 1, while 4 was exclusively yielded in the case of isocyanate/1 = 2. Isothiocyanate showed similar reaction behavior as isocyanate. Polyaddition of 1 with diisocyanates afforded polyamides bearing a bis(dimethylamino)methylenemalonamide group with higher molecular weight. The obtained novel polyamides are soluble in various organic solvents, and reacted with diacid chloride to give crosslinked polymer quantitatively. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3079–3086, 1999     

A Chiral Macrocyclic Tetra-N-Heterocyclic Carbene Yields an “All Carbene” Iron Alkylidene Complex

The first chiral macrocyclic tetra-N-heterocyclic carbene (NHC) ligand has been synthesized. The macrocycle, prepared in high yield and large scale, was ligated onto palladium and iron to give divalent C₂-symmetric square planar complexes. Multinuclear NMR and single crystal X-ray diffraction demonstrated that there are two distinct NHCs on each ligand, due to the bridging chiral cyclohexane. Oxidation of the iron(II) complex with trimethylamine N-oxide yielded a bridging oxo complex. Diazodiphenylmethane reacted with the iron(II) complex at room temperature to give a paramagnetic diazoalkane complex; the same reaction yielded the “all carbene” complex at elevated temperature. Electrochemical measurements support the assignment of the “all carbene” complex being an alkylidene. Notably, the diazoalkane complex can be directly transformed into the alkylidene complex, which had not been previously demonstrated on iron. Finally, a test catalytic reaction with a diazoalkane on the iron(II) complex does not yield the expected cyclopropane, but actually the azine compound.     

Interaction between peroxide ion and phenol group which are coordinated to the same iron(III) ion

We have prepared several new iron(III) complexes with ligands which contain a phenol group; these are tetradentate [(X-phpy)H, X and H(phpy) represent the substituents on the phenol ring and N,N-bis(2-pyridylmethyl)-N-(2-hydroxybenzyl)amine, respectively] and pentadentate ligands [(R-enph-X)H; R=ethyl(Et) or methyl(Me) derivative and H(Me-enph) denotes N,N-bis(2-pyridylmethyl)-N″-methyl-N″-(2″-hydroxyl-benzylamine)ethylenediamine] and have determined the crystal structures of Fe(phpy)Cl₂, Fe(5-NO₂-phpy)Cl₂, and Fe(Me-enph)ClPF₆, which are of a mononuclear six-coordinate iron(III) complex with coordination of one or two chloride ion(s). These compounds are highly colored (dark violet) due to the coordination of phenol group to an iron(III) atom. When hydrogen peroxide was added to the solution of the iron(III) complex, a color change occurs with bleaching of the violet color, indicating that oxidative degradation of the phenol moiety occurred in the ligand system. The bleaching of the violet color was also observed by the addition of t-butylhydroperoxide. The rate of the disappearance of the violet color is highly dependent on the substituent on the phenol ring; introduction of an electron-withdrawing group in the phenol ring decreases the rate of bleaching, suggesting that disappearance of the violet band should be due to a chemical reaction between the phenol group and a peroxide adduct of the iron(III) species with an η¹-coordination mode and that in this reaction the peroxide adduct acts as an electrophile towards phenol ring. The intramolecular interaction between the phenol moiety and an iron(III)-peroxide adduct may induce activation of the peroxide ion, and this was supported by several facts that the solution containing an iron(III) complex and hydrogen peroxide exhibits high activities for degradation of nucleosides and albumin.     

Synthesis and spectral characterization of a new symmetric bidentate Schiff-base and its zinc complexes

A new symmetric bidentate Schiff base N,N′-bis [(E)-3-(2-nitrophenyl)allylidene)]benzene-1,2-diamine (L) and its complexes with general formula ZnLX₂ (X = chloride, bromide, iodide, thiocyanate and azide) are described. The authenticity of the ligand and complexes have been established by microanalysis, electronic, MS, FT-IR, ¹H and ¹³C NMR spectra, and by molar conductivity measurements. All compounds are non-electrolytes in DMF. The analytical data confirmed that the metal to ligand ratio in the complexes is 1 : 1. The complexes have pseudotetrahedral geometry with C_2V point group.     

Synthesis,spectral studies,and antimicrobial activity of binary and ternary Cu(II), Ni(II), and Fe(III) complexes of new hexadentate Schiff bases derived from 4,6-diacetylresorcinol and amino acids

Two new hexadentate N₂O₄ donor Schiff bases, H₄L¹ and H₄L², were synthesized by condensation of 4,6-diacetylresorcinol with glycine and alanine, respectively. The structures of the ligands were elucidated by elemental analyses, IR, ¹H NMR, electronic, and mass spectra. Reactions of the Schiff bases with copper(II), nickel(II), and iron(III) nitrates in 1 : 2 molar ratio gave binuclear metal complexes and, in the presence of 8-hydroxyquinoline (8-HQ) or 1,10-phenanthroline (Phen) as secondary ligands (L′), mixed-ligand complexes in two molar ratios 1 : 2 : 2 and 1 : 2 : 1 (L¹/L² : M : L′). The complexes were characterized by elemental and thermal analyses, IR, electronic, mass, and ESR spectral studies, as well as conductivity and magnetic susceptibility measurements. The spectroscopic data reveal that the Schiff-base ligands were dibasic or tetrabasic hexadentate ligands. The coordination sites with the metal ions are two azomethine nitrogens, two oxygens of phenolic groups, and two oxygens of carboxylic groups. Copper(II) complexes were octahedral and square planar while nickel(II) and iron(III) complexes were octahedral. The Schiff bases, H₄L¹ and H₄L², and some of their metal complexes showed antibacterial activity towards Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Pseudomonas fluorescens and Pseudomonas phaseolicola) bacteria and antifungal activity towards the fungi Fusarium oxysporium and Aspergillus fumigatus.     

Synthetic,magnetic, spectral,antimicrobial and antifertility studies of dioxomolybdenum(VI) unsymmetrical imine complexes having a N ∩ N donor system

Unsymmetrical imine molybdenum(VI) complexes of the type [MoO₂(L¹)(L²)] formed by the interaction of dioxobis(2,4-pentanedionato)molybdenum(VI) in a 1:1:1 molar ratio with different imines derived from the reactions of sulphagunanidine, sulphamethazine, sulphapyridine and sulphadiazine with various aromatic aldehydes and ketones, have been prepared and the products characterized by elemental analysis, molar conductance, magnetic measurements and spectral studies. The complexes have also been tested in vitro. The antifertility screening data indicate the antiandrogenic nature of the complexes. The spectral studies suggest that all the ligands behave in a bidentate fashion, coordinating through the azomethine nitrogen (>C=N–) and other functional group NH as (N N) donors. Studies also reveal that the ligands react with dioxobis(2,4-pentanedionato)molybdenum(VI) to give diamagnetic mononuclear molybdenum(VI) complexes.     

Bis[N-alkyl-NN-di(2-pyridylmethyl)amine]zinc(II) perchlorates display cis-facial stereochemistry in solid state and solution

N-Alkyl-N,N-di(2-pyridylmethyl)amines are ligands commonly used by supramolecular chemists in molecular recognition and sensing applications. The metal coordination complexes of these ligands, in particular those with 2:1 (ligand:metal) molar ratio, have not been sufficiently characterised in solution. In this work, bis[N-alkyl-N,N-di(2-pyridylmethyl)amine]zinc(II) perchlorates are characterised in both solid and solution phases, using X-ray crystallography and NMR spectroscopy, respectively. Only the cis-facial stereoisomer is observed. Density functional theory calculations support the thermodynamic preference for this stereochemistry, as in one representative case the gas phase energy of the cis-facial configuration is lower than those of the trans-facial and meridional configurations by 4.0 and 4.5 kcal/mol, respectively.     

Complexes of Uranyl Nitrate with 2,6‐Pyridinedicarboxamides: Synthesis,Crystal Structure,and DFT Study

Two complexes of uranyl nitrate with N,N,N′,N′‐tetrabutyl‐2,6‐pyridinedicarboxamide (TBuDPA) and N,N′‐diethyl‐N,N′‐diphenyl‐2,6‐pyridinedicarboxamide (EtPhDPA) were synthesized and studied. The complex of tetraalkyl‐2,6‐pyridinedicarboxamide with metal nitrate was synthesized for the first time. XRD analysis revealed the different type of complexation: a 1:1 metal:ligand complex for EtPhDPA and complex with polymeric structure for TBuDPA. The quantum chemical calculations (DFT) confirm that both ligands form the most stable complexes that match the minimal values pre‐organization energy of the ligands.     

Spectral and thermal studies on new hydrazinium metal sulfite dihydrates

Some new hydrazinium transition metal sulfite dihydrate complexes of the formula (N₂H₅)₂M(SO₃)₂(H₂O)₂ where M=Fe, Co, Ni, Cu and Zn have been prepared and characterized by hydrazine and metal analyses, magnetic studies, electronic and infrared spectra and thermal analysis. The magnetic studies coupled with electronic spectra of iron, cobalt, nickel and copper complexes indicate their high spin octahedral nature. However the zinc complex is diamagnetic and show only the charge transfer transition. The infrared spectra shows that both the hydrazinium ions are coordinated to the metal ions, the sulfite ions are present as bidentate ligand. The simultaneous TG-DTA of these complexes were investigated in air and nitrogen atmospheres. In air, cobalt, nickel and zinc complexes give respective metal sulfate as the final residue while iron and copper complexes give the mixture of respective metal oxide and sulfate as the decomposition product. In nitrogen atmosphere respective metal sulfites are formed as the end residue.