Saad Makhseed

The Synthesis of Some Phthalocyanines and Napthalocyanines Derived from Sterically Hindered Phenols

A nucleophilic aromatic substitution reaction between a sterically hindered phenol and 4-nitrophthalonitrile, 3-nitrophthalonitrile or 6-fluoro-2,3-napthalonitrile has been used to prepare precursors for the synthesis of a number of phthalocyanines, such as 1, and naphthalocyanines bearing bulky substituents.

Applications of 2-arylhydrazononitriles in synthesis: Preparation of new indole containing 1,2,3-triazole, pyrazole and pyrazolo[1,5-a]pyrimidine derivatives and evaluation of their antimicrobial activities

In this effort, 2-arylhdrazononitriles were used as key synthons for the preparation of wide variety of new, uniquely substituted heterocyclic substances. In addition, the results of biological evaluations demonstrate that members of the group prepared have promising antimicrobial activities against Gram negative bacteria, Gram positive bacteria and Yeast. In the synthetic sequences, 3-(1-methyl-1H-indol-3-yl)-3-oxo-2-(phenylhydrazono)propanenitrile 2a and its 2-methyl derivative 2b were found to react with hydroxylamine hydrochloride to yield the corresponding indolyl-5-amino-2-phenyl-1,2,3-triazoles 4a,b. These amines react with cyanoacetic acid in presence of acetic anhydride either thermally or under microwave irradiation conditions to yield the corresponding cyanoacetamides 5a,b, which condensed readily with dimethylformamide dimethylacetal to yield the enaminonitriles 6a,b. Whereas heating of 6a,b with hydrazine hydrate affords compound 8, compound 12 is produced when these reactants are subjected to microwave irradiation. We observed that the aminopyrazole 9 reacts with enaminal 13 to yield 14 and that its reactions with enaminones 15 afford 17. Finally, compound 5 reacts with cinnamaldehyde to yield the corresponding Schiffs base 18 that does not undergo cyclization to form the pyridine derivative 19. The activities of all new substances synthesized in this investigation were evaluated against a panel of microbial organisms. The results show that 4a, 4b, 5b and 9b display strong antimicrobial activities against all of the tested organisms.

Clathrate formation from octaazaphthalocyanines possessing bulky phenoxyl substituents: a new cubic crystal containing solvent-filled, nanoscale voids.

The synthesis of octaazaphthalocyanine (AzaPc) derivatives, with bulky phenoxyl substituents placed at eight peripheral positions and containing either H(+), Ni(2+) or Zn(2+) ions in their central cavity, is described. The required precursors, derivatives of pyrazine-2,3-dicarbonitrile, were prepared using a nucleophilic aromatic substitution reaction between 2,6-diisopropylphenol or 2,6-diphenylphenol and 5,6-dichloropyrazine-2,3-dicarbonitrile. Analysis of the resulting AzaPcs by UV/Visible and (1)H NMR spectroscopy confirms that steric isolation of the AzaPc cores was enforced both in solution and in the solid state. X-ray diffraction studies of single crystals of the AzaPcs reveal that solvent inclusion takes place in each case. Of particular significance is the finding that the zinc derivative of 2,3,9,10,16,17,23,24-octa-(2,6-diisopropylphenoxy)octaazaphthalocyanine provides nanoporous cubic crystals, containing massive (8 nm(3)) solvent-filled voids, similar to those of the analogous phthalocyanine derivative. Exchange of the included solvent within the voids can be readily achieved by using a number of alternative solvents including water. Based on the observed loading of included water, the internal volume of this nanoporous cubic crystal appears to be more hydrophilic than its phthalocyanine counterpart.

2-Aminothiophenes as building blocks in heterocyclic synthesis: Synthesis and antimicrobial evaluation of a new class of pyrido[1,2-a]thieno[3,2-e]pyrimidine, quinoline and pyridin-2-one derivatives

Multisubstituted 2-aminothiophenes 1a-c can be readily cyanoacylated via reaction with cyanoacetic acid in presence of acetic anhydride under a microwave irradiation to form the corresponding cyanoacetamides 2a-c, which condensed with DMF-DMA to form the corresponding enamines 4 that reacted with hydrazine hydrate to yield the aminopyrazoles 5. Moreover the cyanoacetamides 2a-c reacted with a variety of arylidenmalononitrile to afford a novel pyrido[1,2-a]thieno[3,2-e]pyrimidine derivatives 12a-o. In addition the enamines 4a,b reacted with malononitrile to afford the pyrido[1,2-a]thieno[3,2-e]pyrimidine derivatives 19a,b. The cyanoacetamides 2a,b reacted also with salicylaldehyde to afford the quinoline derivatives 24a,b. Moreover the cyanoacetamides 2a,b reacted with the enaminones 25a-c to form the corresponding Pyridin-2-one derivatives 29a-c. Reactions of 2a,c with bezenediazonium chloride afford the arylhydrazones 30a,b that reacted with chloroacetonitrile to form the acyclic product 31 which could not be further cyclized to the corresponding 4-aminopyrazole. The X-ray crystallographic analyses of seven products could be obtained thus establishing with certainty the proposed structures in this work. Most of the synthesized compounds in this investigation were tested and evaluated as antimicrobial agents.

Microporous polymeric materials

Abstract Microporous materials are solids that contain interconnected pores of molecular dimensions (i.e. 1 . There are two main classes of microporous materials widely used in industry: crystalline zeolites (aluminosilicates) and activated carbons. In the past decade, there has been an intense effort to optimize the porosity of these materials for various applications 2 , 3 . However, it is recognized that the design of entirely new microporous materials would open up exciting opportunities for fundamental research and industrial applications 3 .

Synthetic strategies towards macrodiscotic materials. Can a new dimension be added to liquid crystal polymers

Macrodiscotic materials are liquid crystalline systems composed of an extended planar structure. It is anticipated that the self-ordering of such materials will result in interesting mechanical and electronic properties. Two synthetic strategies for the realisation of macrodiscotic materials are reviewed: firstly, the preparation of molecules which possess a single extended discotic core and secondly, the assembly of rigid, planar macromolecules composed of a random array of fused discotic units. Oxanthrene-based phthalonitrile precursors, prepared by high yielding reactions between catechols and 4,5-dichlorophthalonitrile, are used to explore both strategies for the synthesis of macrodiscotic materials that incorporate phthalocyanine (Pc) as the discotic unit.

Utility of cyanoacetamides as precursors to pyrazolo〔3,4-d〕pyrimidin-4-ones,2-aryl-6-substituted 1,2,3-triazolo〔4,5-d〕pyrimidines and pyrazolo〔1,5-a〕pyrimidine-3-carboxamides

Cyanoacetamides (7a-c) were prepared via reacting cyanoacetic acid (5) with amines in the presence of acetic anhydride. Compounds (7a-c) coupled with benzenediazonium chloride to yield the phenylhydrazones (8a-c). These reacted with chloroacetonitrile to yield aminopyrazolecarboxamides (lla-c). Reaction of (8a,b) with hydroxylamine hydrochloride in DMF in presence of anhydrous sodium acetate afforded the amino-l,2,3-triazolecarboxamides (36a,b). Also compounds (7a-c) reacted with dimethylformamide dimethylacetal (DMFDMA) to yield the enamines (9a-c) which react with hydrazine hydrate to afford the aminopyrazoles (16a-c). Compounds (16) and (36) reacted with DMFDMA to yield the title heterocyclic derivatives.

Heavy metal effects on physicochemical properties of non-aggregated azaphthalocyanine derivatives

Two series of peripherally substituted azaphthalocyanines (AzaPcs) containing different transition metals (Al(III), Zn(II), Ga(III), In(III) and Fe(II)) were synthesized and studied for their photophysical properties. As confirmed by UV-vis and 1H NMR analyses, the non-aggregation behavior was effectively induced by the applied bulky peripheral substituents which had no effect on the photophysical properties. Tuning the Q-band position was clearly achievable by using different central heavy metals which have considerable effects on the fluorescence quantum yield and singlet oxygen generation efficiency. This comparative study showed an interesting linear relationship between the former and atomic number of the central metal. The indium containing complexes exhibited the best result due to the heavy metal effect and therefore could be promoted as a potential photosensitizer in photodynamic therapy (PDT) application.

Inducing solid-state isolation of the phthalocyanine macrocycle by its incorporation within rigid, randomly shaped oligomers

The synthesis and properties of two non-planar and highly rigid pentamers containing four phthalocyanine units linked, via a spirocyclic fused ring system, to a central phthalocyanine or porphyrin core is described. It is shown that the rigidity of these novel oligomers, together with the large number of structural isomers of irregular shape induced by the presence of the four spiro-centres, inhibits efficient packing of the macrocycles in the solid state. Therefore, the UV–visible absorption spectrum of spin-coated films of these materials is almost identical to that obtained from the non-aggregated oligomers in dilute solution. Nitrogen adsorption measurements indicate a high surface area for one of the pentamers, which is consistent with some degree of microporosity.

Microporous organic polymers incorporating dicarboximide units for H2 storage and remarkable CO2 capture

Anthracene-based microporous polymers comprised of different dicarboximide units (AMPs) are synthesized efficiently by the dioxane forming reactions. AMPs display a BET surface area in the range of 800–1241 m2 g−1, and reversibly adsorb 1.90 wt% H2 at 1.13 bar/77 K with an isosteric heat of adsorption of 7.4 kJ mol−1. The CO2 adsorption studies showed an enhanced affinity with a notable uptake capacity reaching more than 4.2 mmol g−1 at 273 K/1 bar combined with a very high isosteric heat value of adsorption (32 kJ mol−1). CO2 adsorption capacity at high pressure is also evaluated reaching up to 15.61 mmol g−1 at 295 K/40 bar for AMP-3. The hydrogen adsorption and impressive CO2 capture of these materials are attributed to the high concentration of sub-nanometre micropores, as verified by Horvath–Kawazoe (HK) and NLDFT analyses of low-pressure nitrogen adsorption data as well as the benefit of the accessible areas decorated with the imide functionalities within the scaffold of the network polymer. The aforementioned promising results suggest that the incorporation of bismaleimide functional units into the rigid framework structure can improve the performance of AMPs like polymers in gas adsorption applications due to their storage related porous properties.