Synthesis and photophysical properties of porphyrins with fluorenyl pendant arms (original) (raw)
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Tetrahedron, 2012
Two new dendrimeric supramolecular assemblies bearing twelve and twenty-four fluorenyl peripheral donor groups surrounding an organic core have been prepared and studied. These assemblies are composed of three zinc porphyrins possessing each four (ZnTFP) and eight fluorenyl chromophores (ZnOOFP) linked together by a central tris-pyridyl organic ligand. Due to efficient energy transfer between the fluorenyl arms, which act as antennas, and the Zn centres, which act as emitters; these assemblies behave as red emitters after selective UV or visible irradiation. The kinetic stability of these supramolecular assemblies and its impact on their photophysical properties are discussed.
Porphyrins with fluorenyl and fluorenone pendant arms as red-light-emitting devices
Comptes Rendus Chimie, 2006
ABSTRACT Porphyrins with fluorenyl and fluorenone groups at the meso-positions, and their Zn(II) complexes have been synthesized and characterized by 1H NMR, UV–visible and fluorescence studies. Following selective excitation of the pendant arms with UV light, the energy is transferred to the porphyrin core and reemitted as red light. In comparison to tetraphenylporphyrin 5, the luminescence properties are markedly improved. The fluorescence quantum yields of tetrafluorenylporphyrin 1 and tetrafluorenoneporphyrin 2 are 0.22 and 0.25, respectively. To cite this article: C.O. Paul-Roth, G. Simonneaux, C. R. Chimie 9 (2006).
Journal of Photochemistry and Photobiology A: Chemistry, 2012
A p-extended viologen has been synthesized, forming supramolecular complexes with a freebase tetraphenylporphyrin (H 2 TPP) and the cofacial porphyrin dimer with an anthracene spacer [H 4 (DPA)] through p-p interaction in benzonitrile (PhCN). Formation of the H 2 TPP-BHV 2+ supramolecular complex was probed by UV-vis and fluorescence spectra. The fluorescence of H 2 TPP was strongly quenched by electron transfer from the singlet excited state ( 1 H 2 TPP * ) to BHV 2+ in the supramolecular complex. The transient absorption spectrum of the charge-separated (CS) state (H 2 TPP N+ and BHV N+ ) was successfully detected by the laser flash photolysis measurements of the H 2 TPP-BHV 2+ supramolecular complex in PhCN. The lifetime of the CS state of the supramolecular complex was determined as 0.37 ms in PhCN at 298 K. The H 4 (DPA)-BHV 2+ supramolecular complex was formed with a larger formation constant as compared to the H 2 TPP-BHV 2+ supramolecular complex because of the stronger p-p interaction of BHV 2+ with the cofacial porphyrin dimer and the lifetime of the CS state was determined to be 0.59 ms in PhCN at 298 K. { Electronic supplementary information (ESI) available: Absorption spectra in PhCN, femtosecond transient absorption spectra in toluene, and nanosecond transient absorption spectra in benzonitrile. See
Chemistry - A European Journal, 2011
Porphyrin-containing dendrimers have been the subject of intense investigations during the past decade or so, [1] and an important review on the subject was recently written by Li and Aida. A main reason for such interest is that these systems represent good models for the light-harvesting devices of Photosystems I and II in plants and cyanobacteria. In previously reported model systems, the core of the dendri-A C H T U N G T R E N N U N G mers may or may not contain a chromophore or redox-active center, and evidence for antenna and electron transfer process effects similar to those observed in Nature were noted. Except for one earlier example, [3b] all these systems lacked a key element, that is, the central special pair. This entity appears in Nature because the structural flexibility (relative orientation and intermolecular distance) allows modulation of the redox potential and the position of the Soret and Q bands in the visible spectrum. Less obviously, placing two chromophores very close together has the effect of increasing the bandwidth of their absorption and emission spectra. [4] Consequently, for singlet energy transfer processes operating according to the coulombic Fçrster theory, the J integral (i.e., the spectral overlap between the lowest energy absorption band of the energy acceptor and the fluorescence one of the donor) is larger and, therefore, the rate is faster. To design molecular models that resemble the special pairantenna assemblies of photosystems more closely, it now becomes appropriate to couple an artificial pair with dendrimeric antennas and investigate their photophysical properties along with the energy transfer processes from the surrounding antenna molecules to the central artificial special pair. Herein, we report the syntheses and complex photophysical behavior of a series of artificial pair-dendrons (dendron = G1, G2, G3) built upon a dimethylxanthenebis-A C H T U N G T R E N N U N G (metal(II) porphyrin) (metal = zinc or copper) as the central core and artificial special pair (Scheme 1). A zinc(II) tetrameso-arylporphyrin unit is attached to the dendrons and acts as a singlet and triplet energy acceptor or donor, depending on the dendrimeric systems. The presence of the paramagnetic d 9 copper(II) unit in the dendrimers promotes both singlet-triplet energy transfer from the zinc(II) tetrameso-arylporphyrin Abstract: The click chemistry synthesis and photophysical properties, notably photo-induced energy and electron transfers between the central core and the peripheral chromophores of a series of artificial special pair-dendron systems (dendron = G1, G2, G3; Gx = zinc(II) tetra-meso-arylporphyrin-containing polyimides) built upon a central core of dimethylxanthenebisA C H T U N G T R E N N U N G (metal(II) porphyrin) (metal = zinc, copper), are reported. The dendrons act as singlet and triplet energy acceptors or donors, depending on the dendrimeric systems.
New A3B porphyrins as potential candidates for theranostic. Synthesis and photochemical behaviour
Dyes and Pigments, 2019
The study reports a series of results obtained by synthesis, spectral and morphological analysis of new tetrapyrrolic structures: 5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (P1.2), Zn(II)-5-(4-hydroxy-3methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (Zn(II)1.2) and Cu(II)-5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (Cu(II)1.2), as potential candidates for theranostics. Porphyrins were obtained by microwave synthesis under solvent-free conditions and characterized by elemental analysis, FT-IR, UV-Vis and NMR spectroscopies. The absorption properties of the synthetized compounds were studied in different solvents (ethanol, polyethylene glycol 200, dimethylsulfoxide, dichloromethane, chloroform). The spectral profile of the new porphyrins was completed by studying the fluorescence emission and singlet oxygen formation quantum yields. P1.2 and Zn(II)1.2 exhibit fluorescence while for Cu(II)1.2 the fluorescence emission is negligible. P1.2 and Zn(II)1.2 exhibited photodynamic therapy (PDT) acceptable values of singlet oxygen generation. In the case of Cu(II)1.2 this parameter is reduced ca. 5 times. For powdered samples of P1.2 adsorbed onto powdered PEG a detailed study was performed correlating the fluorescence emission intensity with sample absorption to determine the concentration range where aggregation does not occur. Fluorescence emission quantum yields and lifetimes were determined for all samples under study to determine the useful range of concentrations for PDT use. Atomic force microscope (AFM) studies were also made, which exhibit the aggregate species formation for high loadings of the porphyrin P1.2 adsorbed onto specific surfaces.
Chemistry Letters, 1998
The self-assembled macroring N-(Zn-Fb-Zn) 3 has been constructed by intermolecular complementary coordination among three trisporphyrin Zn-Fb-Zn molecules, each of which consists of a central free-base porphyrin and two imidazolyl-zinc-porphyrin ends. Thus, N-(Zn-Fb-Zn) 3 has three slipped-cofacial zinc porphyrin dimers ("special pair model") and three free-base porphyrins, alternately. The zinc porphyrin dimers in N-(Zn-Fb-Zn) 3 are covalently connected by a ring-closing olefin metathesis reaction between the allyl ether groups substituted on the zinc porphyrin dimers, giving a covalently linked macroring C-(Zn-Fb-Zn) 3. The fluorescence spectra of C-(Zn-Fb-Zn) 3 in several solvents show that the photoinduced energy transfer from one of the zinc porphyrin dimers to a free-base porphyrin occurs intramolecularly in toluene, whereas the photoinduced electron transfer predominantly occurs intramolecularly in N,N-dimethylformamide. Treatment of C-(Zn-Fb-Zn) 3 with copper(II) acetate gives a Cu-containing heteromultinuclear porphyrin macroring C-(Zn-Cu-Zn) 3 , demonstrating that C-(Zn-Fb-Zn) 3 could be a good precursor to construct various heteromultinuclear porphyrin macrorings.
Photochem
In the continuation of our sustained interest in porphyrin-based dendrimers and their use as luminescent photosensitizers for two-photon photodynamic therapy (2P-PDT), we wondered about the effect of changing the connectors in our macromolecular structures. We also wanted to initiate preliminary studies on meso-tetraarylporphyrins decorated with more electron-releasing arms. Thus, various meso-tetrafluorenylporphyrin-cored star-shaped and dendrimeric derivatives have been synthesized and characterized, as well as their zinc(II) complexes. In the new dendrimeric derivatives, the peripheral fluorenyl units of the dendrons are linked to the inner core either by N-phenylcarbazole (CCbz) or triphenylamine (CTpa) connectors instead of the more classic 1,3,5-phenylene (CPh) linkers previously used by us. Selected linear and non-linear optical (LO and NLO) properties were then determined for these compounds via absorption or emission studies and by two-photon excited fluorescence (TPEF) mea...
Journal of Drug Targeting, 2014
A series of dendrimer porphyrins (G n DP M ; n ¼ generation of dendrimer, n ¼ 1-3; M ¼ coordination metal, M ¼ freebase, Zn, Pt) were prepared and their photosensitizing properties were compared. All G n DP M exhibited sharp absorption in organic solvents. However, the Soret absorptions of G n DP M (CO 2 H) in 10 mM phosphate buffer solution (pH ¼ 7.4) are broader than those of G n DP M in organic solvents, indicating inhomogeneous microenvironments of the focal porphyrin derivatives. All G 3 DP M (CO 2 H) successfully formed globular polyion complex micelles that were uniform in size. Under dark conditions, all G n DP M (CO 2 H) showed negligible cytotoxicity. However, all samples exhibited concentration-dependent photocytotoxicity under light irradiation. In vitro photocytotoxicity as well as singlet oxygen generation revealed that G 3 DP Zn (CO 2 H) is the best dendritic PS of the three different dendrimer porphyrin species.
High Fluorescent Porphyrin-PAMAM-Fluorene Dendrimers
Molecules, 2015
Two new classes of dendrimers bearing 8 and 32 fluorene donor groups have been synthesized. The first and second generations of these porphyrin-PAMAM-fluorene dendrimers were characterized by 1 H-NMR, 13 C-NMR, FTIR, UV-vis spectroscopy, elemental analyses and MALDI-TOF mass spectrometry. The UV-vis spectra showed that the individual properties of donor and acceptor moieties were preserved, indicating that the new dendrimers could be used as photosynthetic antennae. Furthermore, for fluorescent spectroscopy, these dendrimers showed good energy transfer.
Inorganic Chemistry, 1998
Synthesis of a new symmetrical 1,4,8,11,15,18,22,25-octahexyloxy-2,3,9,10,16,17,23,24-octa-(3,5-dichlorophenyl)phthalocyaninato zinc(II), ZnPc, has been described and characterized by 1 H NMR, 13 C NMR, MS, UVeVis, and IR spectrometry. The newly prepared ZnPc is soluble in organic solvents and is not aggregated in solution. The photophysical properties were studied by steady-state absorption and emission, cyclic voltammetry, and nanosecond transient absorption techniques. The prepared ZnPc absorbs and emits at longer wavelengths compared to that of reported phthalocyanine derivatives. The electron-donating properties of the ZnPc have been examined by mixing it with the electron-accepting dicyanoperylene-3,4,9,10-bis(dicarboximide), PDICN 2 . The recorded nanosecond transient spectra in the visible/near-IR region showed clearly the electron-transfer from the triplet-excited state of the ZnPc to PDICN 2 with a rate of 3.40 Â 10 8 M À1 s À1 . Light absorption in a wide section of the solar spectrum, favorable redox properties, and the electron-transfer properties suggest usefulness of the ZnPc in lightenergy harvesting and developing optoelectronic devices.