V International Conference on the Physical Chemistry of Crown Compounds,Porphyrins, and Phthalocyanines

Russian Chemical Bulletin -     

卟啉和酞菁修饰的单壁碳纳米管的合成及光谱性质

利用5-(4-氨基苯基)-10,15,20-三(3,5-二辛氧基苯基)卟啉和2,9,16-三叔丁基-23-氨基锌(Ⅱ)酞菁通过酰胺键连接方式同时对单壁碳纳米管进行共价修饰, 通过红外光谱、拉曼光谱、X射线光电子能谱和透射电镜对所得碳纳米管复合物进行了表征, 证实了其结构. 紫外-可见吸收光谱和荧光光谱分析表明, 光活性分子卟啉和酞菁均与单壁碳纳米管之间存在较强的电子效应. 经卟啉和酞菁共同修饰的单壁碳纳米管复合物比卟啉和酞菁单独修饰的碳纳米管复合物的吸光范围更宽, 而且分散性较好(309 mg/L), 是潜在的光电转换材料.     

Fluorescence Spectroscopy of Porphyrins and Phthalocyanines: Some Insights into Supramolecular Self-Assembly,Microencapsulation, and Imaging Microscopy

The molecular interactions of anionic tetrasulfonate phenyl porphyrin (TPPS) with poly(amido amine) (PAMAM) dendrimers of generation 2.0 and 4.0 (G2 and G4, respectively) forming H- or J-aggregates, as well as with human and bovine serum albumin proteins (HSA and BSA), were reviewed in the context of self-assembly molecular complementarity. The spectroscopic studies were extended to the association of aluminum phthtalocyanine (AlPCS₄) detected with a PAMAM G4 dendrimer with fluorescence studies in both steady state and dynamic state, as well as due to the fluorescence quenching associated to electron-transfer with a distribution of lifetimes. The functionalization of TPPS with peripheral substituents enables the assignment of spontaneous pH-induced aggregates with different and well-defined morphologies. Other work reported in the literature, in particular with soft self-assembly materials, fall in the same area with particular interest for the environment. The microencapsulation of TPPS studies into polyelectrolyte capsules was developed quite recently and aroused much interest, which is well supported and complemented by the extensive data reported on the Imaging Microscopy section of the Luminescence of Porphyrins and Phthalocyanines included in the present review.     

Investigation of the Chain Length Dependence of kp: New Results Obtained with Homogeneous and Heterogeneous Polymerization

New experimental results were collected for the free radical polymerization of styrene by pulsed laser polymerization in solution or in microemulsion. The location of the point of inflection (on the low molecular weight side) and the maximum of the first peak in the chromatograms (measured by size-exclusion chromatography) was used to extract k_p data. The extent of band broadening was determined with narrow polystyrene standards with an assumed Poisson chain length distribution. For a given experiment both k_p values (obtained via the point of inflection and the maximum) were corrected and thus became identical in most cases. Even after the correction, the effect of chain length dependence persists to a higher chain length.     

Synthesis,Characterization, and Investigation of Cholinesterase Inhibitory Properties of Novel Phthalocyanines

In this study, 4‐{2‐(2‐thienyl)ethoxy}phthalonitrile ( 3 ) and its tetra substituted peripherally metal‐free ( 4 ), lead (II) ( 5 ), magnesium (II) ( 6 ), and cobalt (II) ( 7 ) phthalocyanines were synthesized. The structural characterization of the obtained compounds was performed by a combination of FTIR, ¹H‐NMR, UV–vis, and MALDI‐TOF techniques. The inhibitory properties of these compounds were determined using Ingkaninan's methods against cholinesterase enzymes. Compound ( 7 ) had the highest enzyme inhibitory effect toward AChE and BuChE enzymes with IC₅₀ values of 23.71 ± 0.39 and 27.29 ± 0.22 μM, respectively. The enzyme kinetic study of compound ( 7 ) demonstrated noncompetitive AChE inhibition and uncompetitive BuChE inhibition. The K_i values of compound ( 7 ) against AChE and BuChE were found to 39.15 and 7.25 μM, respectively. In the tested compounds, ( 7 ) deserves further investigation for potential therapeutic candidates of Alzheimer's disease.     

Heterogeneous and Homogeneous Aptamer‐Based Electrochemical Sensors for Thrombin

Nanomolar concentrations of thrombin were electrochemically monitored using heterogeneous switch‐on and homogeneous switch‐off approaches that incorporated ferrocenyl aptamers. For the first time, the heterogeneous approach was coupled to a glucose/glucose oxidase (GOx) amplification‐regeneration system which increased its sensitivity by 2 folds with detection limits of 4.3 nM and 2.5 nM in the absence and presence of glucose/GOx, respectively. We also present a new homogeneous system involving the ferrocenyl aptamer binding thrombin in solution causing a significant decrease in its diffusion coefficient. Thus the ferrocene anodic current decreased at an unmodified gold electrode with detection limit of 3.9 nM and 12 times larger linear range than the heterogeneous method.     

Bringing Homogeneous Iron Catalysts on the Heterogeneous Side: Solutions for Immobilization

Noble metal catalysts currently dominate the landscape of chemical synthesis, but cheaper and less toxic derivatives are recently emerging as more sustainable solutions. Iron is among the possible alternative metals due to its biocompatibility and exceptional versatility. Nowadays, iron catalysts work essentially in homogeneous conditions, while heterogeneous catalysts would be better performing and more desirable systems for a broad industrial application. In this review, approaches for heterogenization of iron catalysts reported in the literature within the last two decades are summarized, and utility and critical points are discussed. The immobilization on silica of bis(arylimine)pyridyl iron complexes, good catalysts in the polymerization of olefins, is the first useful heterogeneous strategy described. Microporous molecular sieves also proved to be good iron catalyst carriers, able to provide confined geometries where olefin polymerization can occur. Same immobilizing supports (e.g., MCM-41 and MCM-48) are suitable for anchoring iron-based catalysts for styrene, cyclohexene and cyclohexane oxidation. Another excellent example is the anchoring to a Merrifield resin of an Fe^II-anthranilic acid complex, active in the catalytic reaction of urea with alcohols and amines for the synthesis of carbamates and N-substituted ureas, respectively. A SILP (Supported Ionic Liquid Phase) catalytic system has been successfully employed for the heterogenization of a chemoselective iron catalyst active in aldehyde hydrogenation. Finally, Fe^III ions supported on polyvinylpyridine grafted chitosan made a useful heterogeneous catalytic system for C–H bond activation.     

Water-Soluble Ligands,Metal Complexes,and Catalysts: Synergism of Homogeneous and Heterogeneous Catalysis

Rapid developments in the field of catalysis are leading to an increased demand for tailor-made catalysts. Water-soluble complex catalysts, which are being intensively investigated at the present time, combine the advantages of homogeneous and heterogeneous catalysis: simple and complete separation of the product from the catalyst, high activity, and high selectivity. From the large number of available water-soluble ligands, the appropriate catalysts can be developed for many reactions. The industrial applications in the fields of hydrogenation and hydroformylation have already indicated the wide scope of this type of catalyst. In addition, the annual production of 300 000 tons of butyraldehyde through application of water-soluble rhodium complexes at Hoechst AG in Oberhausen, Germany, has demonstrated the industrial importance of the concept of complex-catalyzed reactions in aqueous two-phase systems. The efficient operation of catalytic processes increasingly requires the loss-free recycling of the noble metal catalyst, and this can be simply and economically realized in two-phase systems. Special applications in biochemical problems open up developments in the field of water-soluble transition metal complexes that far transcend the familiar kinds of homogeneous catalysis. In the near future, the investigation and application of metal complex catalysts that are compatible with the physiological, cheap, and environmentally friendly solvent, water, is likely to become a high priority in catalysis research.     

Phenazine Radical Cations as Efficient Homogeneous and Heterogeneous Catalysts for the Cross-Dehydrogenative Aza-Henry Reaction

The redox activity of molecular phenazine catalysts has been previously exploited for aerobic oxidative amine homo- and cross-coupling reactions. In this contribution, we have extended the reaction scope of this novel type of organocatalyst and used them in the cross-dehydrogenative aza-Henry coupling of isoquinolines with nitromethane under aerobic conditions. Additionally, we have designed and prepared a novel porous organic polymer by cross-linking of tetrakis(4-bromophenyl)silane and dihydrophenazine through Pd-catalyzed Buchwald-Hartwig cross-coupling. This new type of heterogeneous catalyst, apart from being robust and easily reusable, also showed outstanding catalytic activities and improved selectivity compared to its molecular counterpart. A plausible reaction mechanism was proposed based on spectroscopic and kinetic measurements.     

A Model for Simultaneous Homogeneous and Heterogeneous Nucleation in the Case of Slow Reaction Rate

(Gd(x)Y(1-x))(2)O(3):Eu [x=0, 0.25, 0.5, 0.75, 1.0] phosphor particles with 6 at.% Eu dopant of total concentration were prepared using spray pyrolysis. The effects of composition on the morphology, crystallinity, and photoluminescence characteristics of composite particles were investigated. The morphological control of (Gd(x)Y(1-x))(2)O(3):Eu particles in spray pyrolysis was also attempted by using colloidal and aqueous solutions. The particles prepared from colloidal solutions containing small amounts of Gd or Y hydroxy carbonate sol as seed material had spherical and filled morphology after the post-treatment at high temperature. On the other hand, the (Gd(x)Y(1-x))(2)O(3):Eu particles prepared from aqueous solutions were hollow and porous after post-treatment in all compositions. Particles prepared from colloidal solutions had photoluminescence emission intensities higher than those of particles prepared from aqueous solutions. Copyright 2000 Academic Press.     

Development of a Novel Homogeneous and Heterogeneous Pd Catalytic System for Organic Transformations

The results of our new finding on homogeneous and heterogeneous palladium catalytic system for oxidation of alcohols and alkenes using molecular oxygen are described together with several successful attempts to make the system recyclable from the viewpoint of environmental and economical concerns. In addition, some novel organic transformations of tert-cyclobutanols and cyclobutanone oximes are also presented where -carbon elimination involving C–C bond fission is a key step.     

Bridging the Gap: From Homogeneous to Heterogeneous Parahydrogen-induced Hyperpolarization and Beyond

Demonstration of parahydrogen-induced polarization effects in hydrogenations catalyzed by heterogeneous catalysts instead of metal complexes in a homogeneous solution has opened an entirely new dimension for parahydrogen-based research, demonstrating its applicability not only for the production of catalyst-free hyperpolarized liquids and gases and long-lived non-equilibrium spin states for potential biomedical applications, but also for addressing challenges of modern fundamental and industrial catalysis including advanced mechanistic studies of catalytic reactions and operando NMR and MRI of reactors. This essay summarizes the progress achieved in this field by highlighting the research contributed to it by our colleague and friend Kirill V. Kovtunov whose scientific career ended unexpectedly and tragically at the age of 37. His role in this research was certainly crucial, further enhanced by a vast network of his contacts and collaborations at the national and international level.     

Determination of Singlet Oxygen Production and Antibacterial Effect of Nonpolar Porphyrins In Heterogeneous Systems

ABSTRACT

The possibility of using the iodide method and the method of bleaching of 4-nitroso-N, N'-dimethylaniline, developed originally for homogeneous aqueous medium for the determination of singlet oxygen production, was tested for water-insoluble nonpolar senzitizers adsorbed on the silica gel support. Sensitizers of the porphyrin and metalloporphyrin type (tetraphenylporphin (TPP), protoporphyrin IX (PPIX), tetra(4-nitrophenyl)porphin (TPP(NO₂)₄ and complexes of TPP with some divalent and trivalent metals, Cd(II)TPP, Zn(II)TPP, Co(II)TPP, Cu(II)TPP, Ni(II)TPP, Mn(II)TPPCI, and Fe(II)TPPCl) were used as model compounds. It was found that both methods used gave similar values of ¹O₂. The relative ¹O₂ production of the compounds studied decreases in the order PP=Zn(II)TPP=Cd(II)TPP > TPP(NO₂)₄> PPIX> nonactive substances.

The cytotoxic effect of ¹O₂ Produced by these substances on the silica gel support was tested using E. coli DHS-alfa bacteria. The relative ¹O₂ production values correlate with the antibacterial activity of the adsorbed substances exposed to light.     

Synthesis,Characterization and Investigation of Electrochemical and Spectroelectrochemical Properties of Peripherally Tetra Diethoxypropan Substituted Phthalocyanines

In this study novel peripherally tetra 1,3-diethoxy-2-propanol substituted Co(II), Cu(II), Mg(II), Ni(II) Zn(II) phthalocyanine derivatives were prepared. The characterization of the novel compounds was made by FT-IR, ¹H-NMR, UV-vis and MALDI-TOF mass. Electrochemical, in-situ spectroelectrochemical and electrocolorimetric measurements have been carried out with the aim to determine the redox properties, to illuminate reaction mechanism and the effect of substituent and metal center. Moreover, the color properties and aggregation tendency of compounds were also investigated.     

Transformations of Isocaryophyllene Diepoxide under Conditions of Homogeneous and Heterogeneous Acid Catalysis

Transformations of isocaryophyllene diepoxide (an isomer of widely spread natural sesquiterpene) were studied in various acidic media under conditions of homogeneous and heterogeneous catalysis. A number of previously unknown compounds were thus obtained. The experimental data were compared with the results of molecular-mechanics and quantum-chemical simulation of the most probable transformation paths.