Dendritic Porphyrins Research Articles

Dendritic porphyrins as promising sensitizers in aqueous media. From synthesis to potential applications

A homologous series of first generation dendritic phorpyrins (Pf-Ds) were recently synthesized and characterized by conventional methodologies. The main goal of this work was to achieve a practical way of solubilizing this class of efficient sensitizers in high water content aqueous-alcoholic media, by functionalization of a free-base tetraphenyl-porphyrin with polyamido-amine dendritic branches. A high solubility of the Pf-Ds was obtained in such media, whereas the non-functionalized porphyrin was insoluble. Moreover, the photophysical properties of the compounds were evaluated in aqueous solvent by several steady-state and time resolved spectroscopic techniques. The comparison between these data and those in a typical solvent demonstrated that the porphyrin does not show aggregation, retaining its sensitizing capability completely unaltered. Finally, preliminary tests were performed in order to evaluate the ability of Pf-Ds to sensitize the photodegradation of some probe molecules. Effective degradation of the probes was observed after less than 30 min of irradiation with visible LEDs, which is promising for the future application of these compounds as efficient pollutant removers.

Dendronized Porphyrins: Molecular Design and Synthesis

Abstract:In this review, we report different methods and strategies to synthesize flexible and rigid dendronized porphyrins. We will focus on porphyrin dendrimers that have been reported in the last 10 years. Particularly, in our research group, we have designed and synthesized different series of dendronized porphyrins (free base and metallated) with pyrene units at the periphery and Fréchet-type dendritic arms. The Lindsey methodology has allowed the synthesis of meso-substituted porphyrins with various substitution patterns, such as symmetric, dissymmetric, or unsymmetric. Porphyrin dendrimers have been prepared by different synthetic methodologies; one of the most reported being the convergent method, where the dendrons are first prepared and further linked to a meso-substituted functionalized porphyrin unit, which will constitute the core of the dendrimer. Another interesting synthetic approach is the use of a reactive dendron bearing a terminal aldehyde functional group to form the final porphyrin core. In this way, a two-armed dendronized dissymmetric porphyrin core can be prepared from a dendritic precursor and a dipyrromethene derivative. This strategy is very convenient to prepare low-generation dendritic porphyrins. The divergent approach is another well-known methodology for porphyrin dendrimer synthesis, mostly used for achieving highgeneration dendrimers. Click chemistry reaction has been advantageous for the development of more complex porphyrin dendritic structures. This reaction presents important advantages, such as high yields and mild reaction conditions, which permit the assembly of different multiporphyrin dendritic structures. In the constructs presented in this review, the emission of the porphyrin moiety has been observed, leading to potential applications in artificial photosynthesis, sensing, nanomedicine, and biological sciences.

Design of flexible dendritic systems bearing donor-acceptor groups (pyrene-porphyrin) for FRET applications

Herein, we report the synthesis and characterization of a novel series of dendritic compounds, bearing peripheral pyrene groups and a porphyrin core, of zero and first generation with different spacer lengths. These compounds were further metallated with Zn(II) and Mg(II). The optical properties of these dendritic molecules were studied by absorption and fluorescence spectroscopy. After metallation, the dendritic porphyrins exhibited a red shift in the Soret absorption band and a blue shift in the emission band. All compounds exhibited high energy transfer efficiency, reaching values of EFRET above 99%.

Doxorubicin-loaded redox-responsive amphiphilic dendritic porphyrin conjugates for chemotherapy and photodynamic therapy

The reduction-responsive dendritic copolymer (TPP-S-S-G3) was developed to construct a drug carrier for encapsulation of hydrophobic drug (DOX) for the combination treatment between chemotherapy and PDT.

Corrole‐Decorated Porphyrin Dendrimer and Its Selective Metallation

AbstractUtilization of 4‐formylbenzaldehyde in the 2+1 approach for synthesis of corroles was regulated as to lead to either the one‐pot synthesis of meso‐meso′‐linked dimeric corrole or to a monomeric corrole with a free formyl group. The latter was used as synthon for the preparation of a dendritic porphyrin with four corroles. The different chelating properties of the similar macrocycles allow for selective insertion of zinc(II) into the central porphyrin and cobalt(III) into the peripheral corroles.

Photodynamic therapy of oligoethylene glycol dendronized reduction-sensitive porphyrins.

OEGylation of porphyrins via a disulfide linkage to form a novel class of dendritic porphyrin photosensitizers (PSs) is presented. These amphiphilic PSs possess precise molecular structures which could self-assemble into spherical aggregates in aqueous solutions. Their thermoresponsiveness was investigated using UV-Vis spectroscopy, and their reduction responsive properties were inspected using dynamic light scattering and TEM measurements. Moreover, the uptake of porphyrin-containing dendritic micelles by cells and release of reduction-sensitive PSs were investigated using flow cytometry and confocal laser scanning microscopy. The results showed that the cellular uptake of dendritic micelles was more than that of free porphyrin and the uptake process was time-dependent. Additionally, the phototoxicity of these dendritic PS micelles was investigated by MTT assay. It was found that dendritic micelles exhibited efficient phototoxicity to cancer cells while the free porphyrin had nearly no toxicity under light irradiation. All results indicate that these dendritic PSs are promising for photodynamic therapy.

Effect of polymer matrix on the sensitivity of microfibrous fluorescent chemosensor containing dendritic porphyrin for the detection of dopamine

To use as a fluorescent chemosensor for detecting dopamine, dendritic porphyrin (Den-Por(Zn))-incorporated electrospun microfibrous membranes, polycaprolactone (PCL)-Por(Zn), poly(vinyl acetate) (PVAc)-Por(Zn), and poly(4-vinylpyridine) (P4VP)-Por(Zn), were fabricated. The resulting fibers exhibited a fully interconnected pore structure with narrow pore size distribution. Energy dispersive X-ray spectroscopy and attenuated total reflectance–Fourier transform infrared (ATR–FTIR) results clearly revealed the introduction of dendritic porphyrin on the surface of electrospun membranes. Among the electrospun membranes, P4VP-Por(Zn) exhibited highest sensitivity to dopamine. P4VP-Por(Zn) showed more hydrophilic property than other fibers, and the strong intermolecular interaction between P4VP and dopamine was observed. Therefore, the significant decline of fluorescence intensity even after the reaction with low concentrations of dopamine was measured, in which dopamine probably acted as a quencher. This is attributed to the complex formation between dopamine and Zn of Den-Por(Zn) introduced into the P4VP-Por(Zn) via the chelation.

Synthesis and Optical Properties of Dendritic Porphyrin-Erbium Complexes

Organic compound with lanthanide complexes have been greatly researched for the advance of optical property and processibility to apply on optical amplifiers. We studied on lanthanide metal-dendritic porphyrin complex in solution state. Peripherally substituted carboxylic groups on G1 and G2 dendritic porphyrins were gradually occurred to form the precipitation with increasing Er3+ions in solution state. With increasing the amount of Er3+ions resulting complexes begin to form loosely cross-linked complexes causing precipitation in THF solution. No optical change of G2-Er complex was observed in the presence of large excess (10eq-100eq) of strong chelating ligand such as EDTA in THF solution, which is indicative that G2-Er is chemically very stable because of so-called dendritic chelating effect.

Fluorescent chemosensor for the detection of histamine based on dendritic porphyrin-incorporated nanofibers

To use as a fluorescent chemosensor for detecting histamine, dendritic porphyrin-incorporated nanofibers, PCL-Por and PCL-Por(Zn), were fabricated by electrospinning. The resulting electrospun nanofibers exhibited a fully interconnected pore structure with narrow pore size distribution. EDX, ATR–FTIR and XPS results clearly revealed the existence and homogenous distribution of dendritic porphyrin on the surface of nanofibers. PCL-Por(Zn) nanofiber showed the fluorescence spectra change after the reaction with various histamine solutions. It could be seen that even in the lower histamine solution the fluorescence intensity reduced with increasing histamine concentration, in which histamine probably acted as a quencher. This is due to the complex formation between histamine and Zn of Den-Por(Zn) introduced into the PCL-Por(Zn) nanofiber via a coordination.

卟啉有机纳米聚集体的研究 Research the Property of Organic Nano Gathered Based on Porphyrin

本文设计合成了两个以卟啉为核心尾端分别连有亲水基团和疏水基团的枝状化合物，并对其在水中的聚集行为进行研究及表征。通过紫外可见(UV-vis)吸收光谱和扫描电子显微镜(SEM)的分析，发现在连有疏水基团的卟啉化合物1是H型聚集的棒状结构，而连有亲水基团的卟啉化合物2则是J型聚集的空心球结构(直径大约340 nm)，与纳米粒度分析仪计算的结果基本一致。所以我们得出，通过改变卟啉外部的取代基可以调控其纳米聚集体的形貌。 We designed and synthesized dendritic porphyrin which brings hydrophilic groups and hydrophobic groups. Their different aggregation behaviors in aqueous solution were studied by using UV absorption spectroscopy, scanning electron microscopy (SEM) and Nanoparticle technology. Results indicated that porphyrin 1 bearing hydrophobic group can form rod-like structures introduced by H-aggregation. Porphyrin 2 containing hydrophilic moiety can form hollow spherical structures (diameter is about 340 nm) caused by J-aggregation. So we have come, by changing the the por- phyrins external substituents can be modulated by the morphology of nano-aggregates.

Photosensitizing Hollow Nanocapsules for Combination Cancer Therapy

Many layers make light work: Layer-by-layer (LbL) self-assembly of a dendritic porphyrin (red; see picture) and poly(allylamine hydrochloride) (blue) on polystyrene nanoparticles followed by removal of the polystyrene core produces multifunctional hollow nanocapsules. These species can be both loaded with anticancer drugs and used in photodynamic therapy (PDT) and therefore have potential in combined cancer therapy.

Dendritic Porphyrin–Fullerene Conjugates: Efficient Light‐Harvesting and Charge‐Transfer Events

A novel dendritic C(60)-H(2)P-(ZnP)(3) (P=porphyrin) conjugate gives rise to the successful mimicry of the primary events in photosynthesis, that is, light harvesting, unidirectional energy transfer, charge transfer, and charge-shift reactions. Owing, however, to the flexibility of the linkers that connect the C(60), H(2)P, and ZnP units, the outcome depends strongly on the rigidity/viscosity of the environment. In an agar matrix or Triton X-100, time-resolved transient absorption spectroscopic analysis and fluorescence-lifetime measurements confirm the following sequence. Initially, light harvesting is seen by the peripheral C(60)-H(2)P- *(ZnP)(3) conjugate. Once photoexcited, a unidirectional energy transfer funnels the singlet excited-state energy to H(2)P to form C(60)-*(H(2)P)-(ZnP)(3), which powers an intramolecular charge transfer that oxidizes the photoexcited H(2)P and reduces the adjacent C(60) species. In the correspondingly formed (C(60))(*-)-(H(2)P)(*+)-(ZnP)(3) conjugate, an intramolecular charge-shift reaction generates (C(60))(*-)-H(2)P-(ZnP)(3) (.+), in which the radical cation resides on one of the three ZnP moieties, and for which lifetimes of up to 460 ns are found. On the other hand, investigations in organic media (i.e., toluene, THF, and benzonitrile) reveal a short cut, that is, the peripheral ZnP unit reacts directly with C(60) to form (C(60))(*-)-H(2)P-(ZnP)(3) (*+). Substantial configurational rearrangements- placing ZnP and C(60) in proximity to each other-are, however, necessary to ensure the required through space interactions (i.e., close approach). Consequently, the lifetime of (C(60))(*-)-H(2)P-(ZnP)(3) (*+) is as short as 100 ps in benzonitrile.

Intramolecular Axial Ligation of Zinc Porphyrin Cores with Triazole Links within Dendrimers

Stable ligation: A series of dendritic porphyrins, such as that depicted in which benzyl ether dendrons were linked to a porphyrin core through 1,2,3-triazole links, was synthesized. Absorption and fluorescence spectra showed a stable axial ligation at the zinc center of the porphyrin core by triazole links in dendritic wedges and indicated that the position of the triazole links strongly affected the stability of the axial ligation within the dendrimer.A series of dendritic porphyrins 7-9 and 12, in which benzyl ether dendrons were linked to a porphyrin core through 1,2,3-triazole links, were synthesized by Cu(I)-catalyzed cycloaddition of azides and alkynes. Absorption and fluorescence spectra showed a stable axial ligation at the zinc center of the porphyrin core by triazole links in dendritic wedges and indicated that the position of the triazole links strongly affected the stability of the axial ligation within the dendrimer. When the porphyrin core was surrounded by aryl ether dendrons having anionic termini and triazole linkers, a significant rate enhancement for photoinduced electron transfer was observed compared with a similar water-soluble dendritic zinc porphyrin lacking triazole linkers. These triazole links constituted a direct pathway within the dendrimer architecture for electron transfer between the zinc porphyrin core and peripheral electron acceptors.

Supramolecular Assembly of Photofunctional Dendrimers for Biomedical Nano-Devices

Recently, dendrimers are attracting much attention for their development as biomedical nano-devices. In the present paper, we introduce dendrimer photosensitizers, composed of a focal photosensitizing unit surrounded by poly(benzyl ether) dendritic wedges, for photodynamic therapy (PDT). Ionic dendritic porphyrins (DPs) formed supramolecular polyion complex (PIC) micelles through the electrostatic interaction with oppositely charged block copolymers, and showed no self-quenching effect of the focal photosensitizing unit due to the large dendritic wedges. The DP-loaded PIC micelles showed selective accumulation to the ophthalmic neovascular lesion and effective photodynamic effect. For the effective light delivery, dendrimer phthalocyanine (DPc) has also been developed and examined for its photodynamic effect.

Synthesis and characterization of dendritic poly( l-lysine) containing porphyrin–fullerene moieties

Amphiphilic l-lysine dendrons containing porphyrin and fullerene bearing amino acids with the ratio of 2:0, 2:1 and 1:1 were synthesized and characterized using UV–visible absorption spectroscopy, fluorescence emission spectroscopy and transmission electron microscopy. Photoluminescence spectra of these dendrimers showed photoluminescence quenching due to photoinduced electron transfer from porphyrin to fullerene moieties. Transmission electron microscopic observation evidenced the self-association of these dendrimers in water. Controllable and reversible dissociation and re-aggregation of some of the water soluble dendrimers have been investigated using electronic absorption and fluorescence spectra upon the addition of 2-hydroxypropyl-β-cyclodextrin and 1-adamantanecarboxylic acid in their aqueous dispersion. Enhanced ellipticity of dendritic porphyrin–fullerene conjugate compared to that only dendritic porphyrin indicates intramolecular porphyrin–fullerene interactions.

Synthesis and photoelectrical properties of carbon nanotube–dendritic porphyrin light harvesting molecule systems

Supramolecular structures consisting of dendritic porphyrins and single-walled carbon nanotubes (SWNTs) have been prepared and characterized as an efficient donor/acceptor system. Non-covalent interactions enable the pair system to produce suitable electron transfer through a process occurring from the dendritic porphyrin core to the graphenic wall of carbon nanotubes. The role of structure/architecture of our dendritic molecules on SWNT photoelectrical behaviour has been also investigated.

Porphyrin‐Functionalized Dendrimers: Synthesis and Application as Recyclable Photocatalysts in a Nanofiltration Membrane Reactor

The convergent synthesis of a series of porphyrin-functionalized pyrimidine dendrimers has been accomplished by a procedure involving the nucleophilic aromatic substitution (NAS) as a key reaction step. The resulting dendritic porphyrin catalysts show high activity in the light-induced generation of singlet oxygen ((1)O2) from ground-state oxygen. These materials are synthetically useful photosensitizers for the oxidation of various olefinic compounds to the corresponding allylic hydroperoxides. Catalytic activities and regio- and stereoselectivities of the dendritic photosensitizers are comparable to those observed for mononuclear porphyrin catalysts. Recycling of the dendrimer-enlarged homogeneous photocatalysts was possible by solvent-resistant nanofiltration (SRNF) by using an oxidatively stable membrane consisting of a polysiloxane polymer and ultrastable Y zeolite as inorganic filler. Moreover, this membrane technology provides a safe way to isolate the hydroperoxide products under very mild conditions. The membrane showed high retention for the macromolecular catalysts, even in chlorinated solvents, but some oxidative degradation of the porphyrin units of the dendrimer was observed over multiple catalytic runs.

Supramolecular Photovoltaic Cells Based on Composite Molecular Nanoclusters: Dendritic Porphyrin and C60, Porphyrin Dimer and C60, and Porphyrin−C60Dyad

Novel organic solar cells have been prepared using molecular clusters of porphyrin dendrimer (donor) and fullerene (acceptor) dye units assembled on SnO2 electrodes. The molecular clusters of porphyrin with dendritic structure and fullerene exhibit controlled size and shape in contrast with the reference systems (a porphyrin dimer and a porphyrin−fullerene dyad) without dendritic structure in TEM images, which show rather irregular and smaller clusters. The composite molecular nanoclusters of dendritic porphyrin and fullerene prepared in acetonitrile/toluene mixed solvent absorb light over entire spectrum of visible light. The comparison of photoelectrochemical properties of composite molecular cluster of porphyrin and fullerene with that of molecular cluster of porphyrin−C60 dyad with covalent linkage shows the importance of interpenetrating structure in each network to transport hole and electron efficiently. Furthermore, organic photovoltaic cells using clusters of supramolecular complexes of V-shaped ...

Dodecasubstituted Porphyrins — An Easily Accessible Type of Dendritic Porphyrins with Tunable Properties

Dodecasubstituted dendritic porphyrins with nonplanar macrocycles were synthesized by a convergent approach via Lindsey condensation reactions in good yields.

Porphyrin and tetrabenzoporphyrin dendrimers: tunable membrane-impermeable fluorescent pH nanosensors.

The pH dependencies of the UV-vis and fluorescent spectra of new water-soluble dendritic porphyrins and tetrabenzoporphyrins were studied. Because of extended pi-conjugation and nonplanar distortion, the absorption and the emission bands of tetraaryltetrabenzoporphyrins (Ar(4)TBP) are red-shifted and do not overlap with those of regular tetraarylporphyrins (Ar(4)P). When encapsulated inside dendrimers with hydrophilic outer layers, Ar(4)Ps and Ar(4)TBPs become water soluble and can serve as pH indicators, with pK's adjustable by the peripheral charges on the dendrimers. Two new dendritic porphyrins, Gen 4 polyglutamic porphyrin dendrimer H(2)P-Glu(4)OH (1) with 64 peripheral carboxylates and Gen 1 poly(ester amide) Newkome-type tetrabenzoporphyrin dendrimer H(2)TBP-Nw(1)OH (2) with 36 peripheral carboxylates, were synthesized and characterized. The pK's of the encapsulated porphyrins (pK(H)()2(P)(-)(Glu)()4(OH) = 6.2 and pK(H)()2(TBP)(-)(Nw)()1(OH) = 6.3) were found to be strongly influenced by the dendrimers, revealing significant electrostatic shielding of the cores by the peripheral charges. The titration curves obtained by differential excitation using the mixtures of the dendrimers were shown to be identical to those determined for the dendrimers individually. Due to their peripheral carboxylates and nanometric molecular size, porphyrin dendrimers cannot penetrate through phospholipid membranes. Dendrimer 1 was captured inside phospholipid liposomes, which were suspended in a solution containing dendrimer 2. No response from 1 was detected upon pH changes in the bulk solution, while the response from 2 was predictably strong. When proton channels were created in the liposome walls, both compounds responded equally to the bulk pH changes. These results suggest that porphyrin dendrimers can be used as fluorescent pH indicators for proton gradient measurements.