Aluminum Porphyrin Research Articles

Aluminium(iii) porphyrin based dimers and trimers: synthesis, spectroscopy and photochemistry

The well-known oxophilicity of aluminum(III) ion and the well-defined redox and photochemical properties of aluminum(III) porphyrins have been exploited to synthesize the functionally active, 'axial-bonding’-type free base–aluminum(III) porphyrin dimer (H2–Al) and free base–[aluminum(III) porphyrin]2 trimer (H2–Al2), as well as the corresponding copper(II) (Cu–Al, Cu–Al2) and zinc(II) (Zn–Al, Zn–Al2) derivatives. These dimeric and trimeric species have been fully characterized by mass (FAB), UV/VIS, proton nuclear magnetic resonance (1D and 1H-1H COSY) and electron spin resonance spectroscopies and also by the differential pulse voltammetric method. Comparison of their spectroscopic and electrochemical data with those of the corresponding monomeric porphyrins reveals that there is no apparent ring-to-ring interactions in these 'vertically’ linked dimers and trimers. The fluorescence quantum yields and singlet state life times were found to be lower for H2–Al and H2–Al2 in comparison with those of the monomeric chromophores. Electronic energy transfer from the aluminum(III) porphyrin to the free base subunit is detected in both H2–Al and H2–Al2. Finally, a comparison is made between the presently reported aluminum(III) porphyrin based arrays and the previously reported analogous arrays based on tin(IV), germanium(IV) and phosphorous(V) porphyrins with regard to their architectural features, spectroscopic properties and photochemical activities.

Features of Formation of Mixed-Ligand Complexes of Aluminum Tetraphenylporphine

Formation of extra complexes of aluminum tetraphenylporphine was studied by spectrophotometric titration. The effect of the nature of acido ligands on the stability of mixed-ligand complexes of aluminum tetraphenylporphine was determined. The stability constant (log Kst) of sterically unstrained complexes (Cl)Al(L)TPP and (OH)Al(L)TPP increases linearly with increasing basicity of the extra ligand (log KBH+); in the case of sterically distorted complexes (OAc)Al(L)TPP and (Acac)Al(L)TPP changes in log Kst and log KBH+ vary in the same direction. The geometries and energy characteristics of six-coordinate complexes of aluminum porphyrins were calculated quantum-chemically. The calculated enthalpies and Gibbs energies of formation of the complexes are consistent with the experiment. The possibility of the bidentate coordination of acetate and acetylacetonate in the porphyrin extra complexes was proved.

Copolymerization of carbon dioxide and propylene oxide using an aluminum porphyrin system and its components

The catalytic activities of tetraphenylporphinatoaluminum chloride (TPPAlCl) and its propylene oxide adduct (TPPAl(PO)2Cl) were investigated in detail together with a quarternary salt Et4NBr for the copolymerization of carbon dioxide and propylene oxide. In addition, for the components and starting raw materials of the catalyst systems, catalytic activities were examined for the copolymerization. The TPPAlCl catalyst delivered oligomers containing ether linkages to a large extent, regardless of its PO adduction. And cyclic propylene carbonate, as byproduct, was formed in a very small portion. Using the TPPAlCl coupled with Et4NBr as a catalyst system, the formation of ether linkages was reduced significantly in the copolymerization; however, the obtained oligomer still contained ether linkages of 25.0 mol % in the backbone. On the other hand, the formation of cyclic carbonate was increased to 22.4 mol % relative to the oligomer product. The results indicate that the salt, which was coupled with the TPPAlCl catalyst, plays a key role in reducing the formation of ether linkage in the oligomer and, however, in enhancing the formation of cyclic carbonate. Similar results were obtained for the copolymerization catalyzed by the TPPAl(PO)2Cl/Et4NBr system. That is, the formation of ether linkages was not restricted further by the PO adduction of the TPPAlCl component in the catalyst system. Only oligomers with a relatively high molecular weight were produced. This indicates that the PO adduction of the TPPAlCl component contributes highly to the initiation and propagation step in the oligomerization, consequently leading to a relatively high molecular weight oligomer. In contrast, the Et4NBr, as well as the Et2AlCl, produced only cyclic carbonate in a very low yield. Furthermore, tetraphenylporphine exhibited no catalytic activity, regardless of using together with Et4NBr. On the other hand, the Et2AlCl coupled with Et4NBr provided a low molecular weight oligomer having ether linkages of 92.3 mol % in addition to the cyclic carbonate. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3329–3336, 1999

A photoresponsive molecular switch. Reaction of CO2 and epoxide regulated by an aluminum porphyrin–stilbazole system

Abstract

Lewis Acid-Driven Accelerated Living Polymerization of Lactones Initiated with Aluminum Porphyrins. Chemoselective Activation of Ester Groups by Lewis Acid

Ring-opening polymerization of δ-valerolactone (δ-VL) initiated with (5,10,15,20-tetraphenylporphinato)aluminum methoxide ((TPP)AlOMe, 1; X = OMe) was dramatically accelerated upon addition of methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (2a) and bis(2,4,6-tri-tert-butylphenolate) (2b) via coordinative activation of monomer, but was accompanied by transesterification, resulting in broadening of the polymer molecular weight distribution (MWD) at the later stage of polymerization. On the contrary, when methylaluminum bis(2,6-di-X-phenolate)s (X = Cl (2c), Br (2d), I (2e), and Ph (2f)) were used as Lewis acids, the polymerization proceeded also rapidly, retaining the narrow MWD. 13C NMR studies on the Lewis acid (2b or 2f)−δ-VL and −poly(δ-VL) mixtures showed that the coordination abilities of 2b and 2f toward the monomer ester group are comparable to each other, while 2f shows a lower affinity to the polymer ester group than 2b. 2a was also able to accelerate the polymerization of β-butyrolactone (β-BL) with (TPP)AlOMe or (5,10,15,20-tetraphenylporphinato)aluminum chloride ((TPP)AlCl, 1; X = Cl) to different extents depending on the mode of ring scission, where the MWD of the polymer remained narrow throughout the accelerated polymerization (Mw/Mn = 1.1−1.2).

Metalloporphyrin catalysts for living and immortal polymerizations

AbstractThe living polymerization of methyl methacrylate with aluminium porphyrin (1) proceeded dramatically rapidly at room temperature in the presence of sterically crowded organoaluminium compounds such as methylaluminium ortho‐substituted diphenolates (3a − 3g), bis(triphenylmethanolate) (4a), and triphenylaluminium, where undesired reaction between the growing species and the Lewis acids was sterically suppressed. On the basis of this Lewis acid ‐ assisted high‐speed living polymerization, various monomers such as ethyl, propyl, butyl, and dodecyl methacrylates, methacrylonitrile, and 1,2‐epoxypropane were polymerized very rapidly with the aluminium porphyrin ‐ Lewis acid systems.

Accelerated Living Polymerization of Methacrylonitrile with Aluminum Porphyrin Initiators by Activation of Monomer or Growing Species. Controlled Synthesis and Properties of Poly(methyl methacrylate-b-methacrylonitrile)s

Polymerization of methacrylonitrile (MAN) with methylaluminum porphyrin (1) as initiator proceeded rapidly in the presence of methyaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (3). The living polymer of methyl methacrylate (MMA) with a (porphinato)aluminum enolate growing terminal (2), prepared by the polymerization of MMA with 1, also brought about the polymerization of MAN in the presence of 3, affording the corresponding block copolymer with Mw/Mn ranging from 1.1 to 1.3. The living nature of polymerization was confirmed by a delayed sequential two-stage polymerization of MAN initiated with 2 (living prepolymer of MMA on aluminum porphyrin). Pyridine instead of 3 was also effective for the rapid block copolymerization of MAN from 2 to give the block copolymer of controlled molecular weight. Copolymerization of MAN and MMA initiated with 1 proceeded more rapidly in the presence of 3 or pyridine than in the absence. In the presence of 3, the consumption of MAN was much more accelerated than that of ...

The Control of Living Anionic Polymerization by Metalloporphyrins

Abstract The living polymerization of methacrylic esters initiated with aluminium porphyrins was found to be dramatically accelerated upon the addition of organoaluminium or organoboron compounds as a Lewis acidic monomer activator (high-speed living polymerization). Under appropriate conditions, high-molecular-weight poly(methyl methacrylates) (Mn > 500000) having a narrow molecular-weight distribution (Mw/Mn = 1.1—1.2) were synthesized. The key concept of the high-speed living polymerization is the coexistence of nucleophilic growing species and a Lewis acid without a degradative direct reaction.

Living polymerization of methacrylic esters with aluminium porphyrin initiators. Axial ligand exchange activities of alkyl‐ and enolate‐aluminium porphyrins in relation to the polymerization Mechanism

AbstractPolymerization of methacrylic esters such as benzyl methacrylate using as initiator an‐equimolar mixture of methylaluminium 5,10,15,20‐tetraphenylporphine [(TPP)AlMe] and 2,7,12,17‐tetramethyl‐3,8,13,18‐tetramethylporphine [(EtioP)AlMe] proceeded from both initiators, affording a unimodal polymer of narrow molecular weight distribution, although the reactivities of (TPP)AlMe and (EtioP)AlMe are very different from each other. 1H NMR studies on a mixture of two different (porphinato)aluminium enolates, the growing species, and a mixture of a (porphinato)aluminium enolate and an alcoholate, in the absence and presence of methyl methacrylate (MMA or MMA‐d8), indicated an acyclic transition state polymerization mechanism by the participation of two aluminium porphyrin molecules, where the growing species always exchange their enolate ligands whenever it grows.

Lewis Acid-Promoted Anionic Polymerization of a Monomer with High Cationic Polymerizability. Synthesis of Narrow Molecular Weight Distribution Polyoxetane and Polyoxetane-Poly(methyl methacrylate) Block Copolymer with Aluminum Porphyrin Initiators

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLewis Acid-Promoted Anionic Polymerization of a Monomer with High Cationic Polymerizability. Synthesis of Narrow Molecular Weight Distribution Polyoxetane and Polyoxetane-Poly(methyl methacrylate) Block Copolymer with Aluminum Porphyrin InitiatorsDaisuke Takeuchi, Yoshihiko Watanabe, Takuzo Aida, and Shohei InoueCite this: Macromolecules 1995, 28, 2, 651–652Publication Date (Print):January 1, 1995Publication History Published online1 May 2002Published inissue 1 January 1995https://doi.org/10.1021/ma00106a035RIGHTS & PERMISSIONSArticle Views327Altmetric-Citations30LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (263 KB) Get e-Alerts Get e-Alerts

Synthesis of poly(mesogenic methacrylate)s with narrow molecular-weight distributions and their thermal properties

The photopolymerization of various mesogenic methacrylates (MEMs) by using an aluminium porphyrin complex (MTPP) as a photocatalyst has been investigated to show that the resulting polymers are ‘living’ in nature. The polymerization of 6-[4-(4-cyanophenylazo)phenoxy]hexyl methacrylate (MAC) was exceptionally slow when compared to other mesogenic methacrylates, such as those containing ester and/or cyano groups in their mesogens. Interference of the light absorption of MTPP and/or the active propagating chain end by the MAC itself has been considered as being one possible reason for its slow polymerization, as a result of electron spectroscopy studies. Addition of methylaluminium bis(2,4-di-t-butylphenolate) greatly accelerated the polymerization of MEMs initiated with MTPP, as was also observed in the case of methyl methacrylate (MMA), with the exception of MAC, to yield polymers with very narrow molecular-weight distributions. Copolymerization of various MEMs with MMA revealed that both types of monomer are similar in their copolymerization reactivities. Poly(MEM)s formed with MTPP were found to have a higher content of syndiotactic triads than those obtained with a radical initiator. The phase transition behaviour of the polymers that were obtained was studied by focusing on polymers derived from 6{4-[4-(methoxyphenoxy)carbonyl]phenoxy}hexyl methacrylate (MPM). This was because anionically obtained poly(MPM)s with higher contents of syndiotactic triads were reported to show different thermal behaviour from those poly(MPM)s formed via a radical mechanism. It appeared that poly(MPM)s obtained with MTPP have identical thermal properties to the latter but not to the former. The reason for such a discrepancy is not clear at the present time.

Novel catalyst system for the synthesis of poly(alkylene oxide) with controlled molecular weight

AbstractAn organoaluminum compound with bulky phenoxide groups as a Lewis acid can accelerate much the living polymerization of alkylene oxide initiated with aluminum porphyrin by the coordinative activation of the monomer. This concept can be extented to the polymerization initiated with aluminum Schiff base and tetraazaannulene complexes.

Lewis acid-promoted living anionic polymerization of alkyl methacrylates initiated with aluminum porphyrins. Importance of steric balance between a nucleophile and a Lewis acid

It is shown that not only the steric bulk of the Lewis acid (monomer activator) but also that of the nucleophilic growing species is important for realizing the Lewis acid-assisted, controlled anionic polymerization, and a basic concept involving a sterically separated nucleophile-electrophile model is clearly supported

High-Speed "Immortal" Polymerization of Epoxides Initiated with Aluminum Porphyrin. Acceleration of Propagation and Chain-Transfer Reactions by a Lewis Acid

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigh-Speed "Immortal" Polymerization of Epoxides Initiated with Aluminum Porphyrin. Acceleration of Propagation and Chain-Transfer Reactions by a Lewis AcidMasaki Akatsuka, Takuzo Aida, and Shohei InoueCite this: Macromolecules 1994, 27, 10, 2820–2825Publication Date (Print):May 1, 1994Publication History Published online1 May 2002Published inissue 1 May 1994https://doi.org/10.1021/ma00088a024RIGHTS & PERMISSIONSArticle Views544Altmetric-Citations55LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (746 KB) Get e-Alerts Get e-Alerts

Lewis Acid-Assisted Anionic Ring-Opening Polymerization of Epoxide by the Aluminum Complexes of Porphyrin, Phthalocyanine, Tetraazaannulene, and Schiff Base as Initiators

Polymerization of 1,2-epoxypropane (PO) with aluminum porphyrin (2) was substantially accelerated (460 times) by the addition of an organoaluminum compound such as methylaluminum bis-(2,4,6-tri-tert-butylphenolate) (8). The molecular weight of the produced polyether increased linearly with the amount of PO reacted, while the molecular weight distribution (MWD) was invariably narrow throughout the polymerization. Sequential polymerization of PO and 1,2-epoxybutane (BO) with the aluminum porphyrin-8 system afforded the corresponding block copolymer with a narrow MWD

Evidence for the interference of aluminum with bacterial porphyrin biosynthesis.

Aluminum (0.74 mM) was found to retard bacterial growth, and enhance porphyrin formation and excretion in Arthrobacter aurescens RS-2. Coproporphyrin III was shown to be the main porphyrin excreted by aluminum-exposed A. aurescens RS-2 cultures and by RS-2 cultures grown under anoxic conditions. Synthesis and excretion of porphyrins in A. aurescens RS-2 increased in a dose-dependent manner when the bacteria were exposed to increasing aluminum concentrations. Incubation of A. aurescens RS-2 with delta-aminolevulinic acid (delta-ALA, 1.2 mM) brought about the intense formation and excretion of porphyrins by the cells, in the presence or absence of aluminum. delta-ALA slightly enhanced the toxicity of aluminum towards RS-2 bacteria. Furthermore, the intracellular concentration of heme was reduced by 63.9 +/- 8.67% in aluminum-exposed RS-2 bacteria when compared with control cultures. The results are discussed in light of the recent finding concerning aluminum toxicity and porphyrin biosynthesis in microorganisms.

Synthesis of Side-chain Liquid-crystalline Polymers with Narrow Molecular Weight Distribution from Mesogenic Methacrylates Using Aluminum Porphyrin Complex.

Synthesis of side-chain liquid-crystalline polymers with narrow molecular weight distribution and controlled molecular weight from mesogenic methacrylates (MEM) with cyano and/or ester groups in their mesogen was achieved through their photopolymerization using (5, 10, 15, 20-tetraphenylporphinato)aluminum methyl (MTPP) as a photosensitizer. The poly(MEM) obtained using MTPP have slightly higher contents of syndiotactic triads and lower contents of isotactic and heterotactic triads than those obtained with a radical initiator. Further, it was found that the tacticities of poly(MEM) are not much different from those of poly(methyl methacrylate) for both the polymerization systems, i.e., polymerizations with MTPP and the radical initiator. Copolymerizations of MEM initiated with MTPP and the radical initiator yielded copolymers with same compositions as those of monomer mixture in feed. Possibility for the control of molecular weight and its distribution of the copolymers obtained using MTPP has been shown. These results opened the way for the synthesis of block copolymers with liquid-crystalline polymeric chain as one component which are considered to form liquid crystals with unique properties, e.g., dimensional stability.

High‐speed living ring‐opening polymerization by a new catalyst based on metalloporphyrin

AbstractPolymerization of ϵ‐caprolactone and δ‐valerolactone initiated with aluminum porphyrin (1) was much accelerated by the addition of methylaluminum diphenoxide with bulky substituents 2, to give polymers with narrow molecular weight distribution. The polymerization of β‐butyrolactone was also accelerated by 2, to different extents depending on the mode of ring scission. 2 also accelerated the living polymerization of propylene sulfide initiated with zinc porphyrin (3). The effect of 2 is due to the coordinative activation of monomer.

High-speed living anionic polymerization of methacrylic esters with aluminum porphyrin initiators. Organoaluminum compounds as Lewis acid accelerators

The polymerization of methacrylic esters initiated with methylaluminium tetraphenylporphyrin proceeded dramatically rapidly at room temperature in the presence of sterically crowded organoaluminium compounds such as methylaluminium ortho-substituted diphenolates, bis-(triphenylmethanolate), and triphenylaluminium, where undesired reaction between the growing species (enolatoaluminium porphyrin, 2) and the Lewis acids was sterically suppressed. Use of less hindered Lewis acids such as methylaluminum diphenolates having no ortho substituents, bis(diphenylmethanolate), trimethylaluminum for the polymerization of methyl methacrylate under similar conditions resulted in termination of chain growth

Lewis acid ‐ assisted high speed living anionic polymerization by the aluminum porphyrin ‐ Lewis acid systems

AbstractLiving anionic polymerization of methacrylic esters initiated with aluminum porphyrins (1) was found to be dramatically accelerated (e.g., 46 000 times) upon addition of bulky Lewis acids such as alkylaluminum diphenolates (3). Under appropriate conditions, a narrow MWD poly(methyl methacrylate) with Mn exceeding a million could be synthesized. The key conception of this high speed living polymerization is the coexistence of nucleophile (2) and Lewis acid (3) realized by steric repulsion.