Directional synthesis of a dye-linked conducting homopolymer

We report a new synthesis of a 10,20-diphenyl-5,15-bis(4-cyanophenyl)porphyrin (1) and its reduction to give 10,20-diphenyl-5,15-bis(4-formylphenyl)porphyrin (2). When the conducting polymer poly(2',5'-dioctyl-4,4' '-terphenylenecyanovinylene) was prepared in the presence of 2, we obtained a three-domain structure, compound 3, consisting of two homopolymer blocks (J domains) with the porphyrin dye molecule (P domain) in the middle. The JPJ assembly was subjected to photophysical studies where we showed that the J domain could serve as a light-harvesting antenna for the P domain.     

Surface patterning with two-dimensional porphyrin supramolecular arrays

Monolayer arrays of a series of meso-tetra-substituted porphyrins containing octadecyloxy and carboxyl (or pyridyl) groups were prepared on the highly oriented pyrolytic graphite surface at the liquid/solid interface. It was found by means of scanning tunneling microscopy that some porphyrins from this family assemble into various patterns. Specifically, slightly undulated rows are obtained from 5,10,15-tris(4-octadecyloxyphenyl)-20-(4-pyridyl)porphyrin. Meanwhile, rows with more pronounced kinks result from 5-(4-carboxyphenyl)-10,15,20-tris(4-octadecyloxyphenyl)porphyrin. The occurrence of the kinks is dependent on the arrangement of surrounding porphyrin molecules and is determined by intricate interplay between directional hydrogen-bonding interactions and packing forces, including molecule-molecule and molecule-substrate interactions. A double-layer structure is obtained from 5,10-bis(4-carboxyphenyl)-15,20-bis(4-octadecyloxyphenyl)porphyrin, probably through cyclic hydrogen bond formation. This work proves the concept that programmed surface patterning is possible by using porphyrins incorporating directional intermolecular interaction sites.     

A novel method for the synthesis of regiospecifically sulfonated porphyrin monomers and dimers

A novel method has been developed to regiospecifically synthesize water-soluble sulfonated porphyrin monomers tetrakis(4′-sulfonatophenyl)porphyrin, tetrakis(3′-sulfonatophenyl)porphyrin, tetrakis(2′-sulfonatophenyl)porphyrin, tetrakis(2′,5′-dimethyl-4′-sulfonatophenyl)porphyrin, the dimers of 1,2-bis[5,10,15-tri(4′-sulfonatophenyl)porphyrinyl]benzene and 1,2-bis[5,10,15-tri(2′,5′-dimethyl-4′-sulfonatophenyl)porphyrinyl]benzene in high yields through introduction of the trimethylsilyl group on the phenyl rings and reaction with trimethylsilyl chlorosulfonate in CCl₄ solvent.     

Titrations in non-aqueous media: potentiometric investigation of symmetrical and unsymmetrical tetra-aryl porphyrins with 4-nitrophenyl and 4-aminophenyl substituents in nitrobenzene solvent

The basicity of the symmetrical and unsymmetrical tetraphenylporphyrins, namely 5,10,15,20-tetraphenylporphyrin (I) (references), 5-(4-nitrophenyl)-10,15,20-triphenylporphyrin (II), a mixture of 5,10-bis(4-nitrophenyl)-15,20-diphenylporphyrin and 5,15-bis(4-nitrophenyl)-10,20-diphenylporphyrin (III), 5,10,15-tris(4-nitrophenyl)-20-phenylporphyrin (IV), 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin (V), 5-(4-aminophenyl)-10,15,20-triphenylporphyrin (VI), a mixture of 5,10-bis(4-aminophenyl)-15,20-diphenylporphyrin and 5,15-bis(4-aminophenyl)-10,20-diphenylporphyrin (VII), 5,10,15-tris(4-aminophenyl)-20-phenylporphyrin (VIII) and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (IX), was investigated potentiometrically in nitrobenzene solvent. This investigation showed that these compounds are basic rather than acidic. Although they can not be titrated even with tetrabuthylammonium hydroxide, they can easily be titrated with perchloric acid to give well shaped and stoichiometric end-points. In addition they all undergo two proton reactions per porphyrin molecule. However, compounds VI, VII, VIII and IX each shows a second end-point to give three, four, five and six proton reactions, respectively, per porphyrin molecule. Half neutralization potentials (measures of their basicity) of these compounds are: I=368, II=409, III=432, IV=461, V=520, VI=340, VII=302, VIII=238 and IX=225 mV versus Ag/AgCl in methanol. These potentials clearly indicate that, if para-hydrogen with respect to the porphyrin core of tetraphenylporphyrin (I) is replaced with an acidifying nitro group (II, III, IV and V) the basicity of I decreases. This decrease is approximately proportional to the number of nitro groups. Each nitro group decreases the half neutralization potential by about 35 mV. On the other hand, if para-hydrogen indicated above is replaced with a basifying amino group (VI, VII, VIII and IX) the basicity increases. This increase is also approximately proportional to the number of amino groups. Each amino group increases the half neutralization potential by about 36.7 mV. The values 35 and 36.7 mV indicate that in nitrobenzene solvent the electron releasing power of an amino group to the porphyrin system is a little stronger than the electron withdrawing power of a nitro group from the porphyrin system. All these observations reveal that the nitrogen atoms at the core of the porphyrin molecules are strongly influenced by changes at the periphery of the molecules, which is a very good indication that the substituted phenyl groups and the cores of the porphyrins are nearly in the same plane.     

Deposition of thermally unstable molecules with the spray-jet technique on Au(111) surface

A porphyrin derivative (5,15-bis(4-ethynylphenyl)-10,20-bis(3,5-di-tert-butylphenyl)porphyrin: trans-BETBPP) possessing chemically reactive substituents was successfully deposited on an Au(111) surface with a new molecular beam deposition system with use of a spray-jet technique (Spray-jet-MBD) without denaturing the molecules. The deposited molecular overlayers were observed at 77 K under ultrahigh vacuum condition by scanning tunneling microscopy (STM). They form two different overlayer structures: a linear arrangement and a square lattice structure. In these overlayers, some molecules were accidentally moved by STM tip agitation, which indicates that the molecules were not polymerized during the deposition process.     

Raman and infrared spectral study of meso-sulfonatophenyl substituted porphyrins (TPPSn,n = 1, 2A, 2O, 3, 4)

Raman and IR spectra of the free base p-sulfonatophenyl and phenyl meso-substituted porphyrins [5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4); 5,10,15-tris(4-sulfonatophenyl)-20-phenyl-porphyrin (TPPS3); 5,10-bis(4-sulfonatophenyl)-15,20-diphenylporphyrin (TPPS2A); 5,15-bis(4-sulfonatophenyl)-10,20-diphenylporphyrin (TPPS2O); and 5-(4-sulfonatophenyl)-10, 15,20-trisphenylporphyrin (TPPS1)] and their N-diprotonated derivatives (porphyrin diacids) were studied. The Raman spectra of the deuterated analogues of these porphyrins, in which the central hydrogen atoms were substituted with deuterium, were also measured. The observed vibrational bands were assigned on the basis of the deuteration shifts and compared with the structural analogues of these compounds. In IR spectra of the free-base porphyrins, the p-sulfonation of phenyl groups results in evident alteration for the phenyl modes and the porphyrin skeleton modes that are strongly coupled with phenyl vibrations. While the p-sulfonation of phenyl groups causes only slight changes for the high-frequency Raman bands (> 850 cm(-1)), dramatic shifts and band splitting were observed in the low-frequency region (< 500 cm(-1)) of Raman spectra. The observed differences of low-frequency Raman spectra were attributed to the alteration of the structure of the porphyrin ring, especially the CalphaCmCalpha bond-angles, by different meso-sulfonatophenyl substitutions. In addition, different packing style of TPPSn molecules in the aggregates is also responsible for the alteration of the vibrational spectra of the aggregated TPPSn.     

Meso-substituted porphyrin photosensitizers with enhanced near-infrared absorption: Synthesis,characterization and biological evaluation for photodynamic therapy

Porphyrin derivatives are widely explored and used in photodynamic therapy, for their marvelous therapeutic properties. In order to fill in the gaps of insufficient photosensitizers with near-infrared absorption, three porphyrin molecules, 5,10,15,20-tetrakis(3,4-bis(2-(-2-(2-hydroxyethoxy)ethoxy)ethoxy)benzyl)zinc porphyrin(P1), 5,15-bis(3,4-bis(2-(-2-(2-hydroxyethoxy)ethoxy)ethoxy)benzyl)-10,20-bis(2-(2-(2-(4-ethynylphenoxy)ethoxy)ethoxy)ethanol)zincporphyrin(P2),5,15-bis(3,4-bis(2-(-2-(2-hydroxyethoxy)ethoxy)ethoxy)benzyl)-10,20-N,N-dibutyl-4-ethynylaniline zinc porphyrin(P3), were designed and synthesized targeting for more efficient cancer treatment. Excellent photophysical properties were illustrated by UV–vis absorption and emission spectra with enhanced absorbance between 650 and 750?nm and fluorescence emission within 600–800?nm. Besides, with high ¹O₂ quantum yield, especially P2 (0.89), all porphyrins were further evaluated in vitro by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay against Hela cells and exhibited negligible dark toxicity and robust phototoxicity. Fluorescence confocal laser microscopy confirmed cellular uptake and diffusion of these porphyrins, therefore demonstrated their potential and promising applications in photodynamic therapy.     

Synthesis of a phosphorus-containing hybrid porphyrin

A phosphorus-containing hybrid porphyrin was successfully prepared via the BF3-promoted dehydrative condensation between sigma4-phosphatripyrrane and 2,5-bis[hydroxy(phenyl)methyl]thiophene. The NMR and UV-vis absorption spectra, electrochemical measurements, and DFT calculations revealed that the sigma3-P,N2,S-hybrid porphyrin exhibits high aromaticity as an 18pi-electron system in terms of both geometric and magnetic criteria. [structure: see text]     

Synthesis and investigation of photovoltaic properties for polymer semiconductors based on porphyrin compounds as light-harvesting units

We reported on two polymer semiconducting copolymers based on porphyrin compounds, poly[9,9-dioctylfluorene-co-5,15-bis(hexoxybenzyl)-10,20-bis(benzo-4-yl)porphyrin] (PFPor) and poly[9-(heptadecan-9-yl)carbazole-co-5,15-bis(hexoxybenzyl)-10,20-bis(benzo-4-yl)porphyrin] (PCPor), for use as organic photovoltaic materials. The thermal, optical, electrochemical, and photovoltaic properties of the two polymers were investigated. In addition, PC₆₁BM and PC₇₁BM were introduced as acceptor materials to confirm the acceptor effect in bulk heterojunction photovoltaic devices. Moreover, in order to establish acceptor effects, morphologies of polymer/PCBM blend films were analyzed through atomic force microscopy (AFM). PFPor and PCPor exhibited the best device performance with power conversion efficiencies (PCE) of 0.62% and 0.76%, respectively, upon the introduction of PC₇₁BM as the acceptor in the device where 86 wt.% of the PC₇₁BM was contained in the active layer (pol:PC₇₁BM = 1:6, w/w).     

Porphyrin-acetylene-thiophene polymer wires

5,15-Bis[acetylene-4-(ethylenedioxy)thiophene]-10,20-bis(4-carboxyphenyl)porphyrin was synthesized by a Sonogashira coupling and polymerized to fibres; TEM and AFM images show uniform porphyrin wires with a length of several micrometers and a thickness of less than 4 nm.     

Metalloporphyrins as chemical shift reagents: the unambiguous NMR characterization of the cis- and trans-isomers of meso-(bis)-4′-pyridyl-(bis)-4′-carboxymethylphenylporphyrins

The condensation of pyrrole with 4-pyridylcarboxyaldehyde and methyl 4-formyl benzoate under Adler-Longo conditions yielded the series of meso-(4′-pyridyl)/(4′-carboxymethylphenyl)porphyrins as a mixture. Careful column chromatography afforded each isomer in pure form. In this paper we focus on the two bis-substituted isomeric meso-porphyrins, 5,10-bis(4′-pyridyl)-15,20-bis(4′-carboxymethylphenyl)porphyrin and 5,15-bis(4′-pyridyl)-10,20-bis(4′-carboxymethylphenyl)porphyrin, respectively, 4′-cis and 4′-transDPyDMeP. The assignment of the geometry of the two isomers was performed by ¹H NMR spectroscopy on the trinuclear adducts [(4′-cisDPyDMeP){Ru(TPP)(CO)}₂] and [(4′-transDPyDMeP){Ru(TPP)(CO)}₂], obtained by selective coordination of [Ru(TPP)(CO)(EtOH)] (TPP=tetraphenylporphyrin) to the peripheral nitrogen atoms. The axially bound ruthenium porphyrins act as chemical shift reagents on the central porphyrin, allowing a clear distinction of the pyrrole proton resonances and consequent unambiguous assignment of the geometry of each isomer based upon symmetry considerations.     

系列巯基苯基卟啉自组装膜的光谱和电化学性质

考察了系列巯基苯基卟啉自组装膜的光谱及电化学特征。 结果表明,与溶液中巯基苯基卟啉的光谱相比,自组装膜中卟啉分子的吸收和荧光光谱均发生了明显变化,随着卟啉分子中巯基数目的增加,其荧光峰依次发生红移;不同巯基苯基卟啉自组装膜修饰电极对电解液中电对的电子转移阻碍能力不同,由5,10-二[4-(3-巯基丙氧基)-苯基]-15,20二苯基卟啉形成的卟啉自组装膜的阻碍作用最强,膜表面覆盖度最致密。     

Reversible switching between linear and ring polystyrenes bearing porphyrin end groups

A route to macrocyclic polymers based on a new unimolecular ring-closure process has been investigated. It involves the direct end-to-end coupling of an α,ω-bis[chloroiron(III) meso-tetraphenylporphyrin] telechelic linear polystyrene synthesized by living polymerization followed by chain-end functionalization. The corresponding macrocyclic polystyrene was obtained readily and selectively by intramolecular condensation of the α,ω-bis[chloroiron(III) meso-tetraphenylporphyrin] polymer ends in the presence of a base to yield a diiron(III)-μ-oxobis(porphyrin) dimer as ring-closing unit. Addition of dilute HCl was shown to rapidly reconvert the diiron(III)-μ-oxobis(porphyrin) unit into the initial bis[chloroiron(III) porphyrin], demonstrating the selectivity and complete reversibility of the cyclization process. The synthesis and detailed structural characterization of the α,ω-homodifunctional precursor and the corresponding macrocyclic polystyrene along with an analysis of the porphyrin dimerization reaction using NMR spectroscopy and size-exclusion chromatography coupled with a diode array detector are presented.     

Synthesis of novel dendrimers containing pyrimidine units

A novel convergent approach to dendritic macromolecules is described in which 4,6-dichloro-2-(4-methoxyphenyl)-pyrimidine is used as the building block. The nucleophilic aromatic substitution reaction at this AB₂-monomer was used as the key step in the propagation of the dendrons. Different core reagents were used to form the dendrimers, including a 5,15-bis(pyrimidyl)porphyrin core. Fourth-generation dendrons and third-generation dendrimers could be synthesized. The presented dendrimers are promising candidates to be used in applications where a more rigid structure and a larger resistance towards the applied conditions is required.     

Investigation of tightly coupled porphyrin arrays comprised of identical monomers for multibit information storage

Our prior designs for molecular-based information storage devices have employed multiple redox-active units organized in weakly coupled, covalently linked arrays. To explore a simpler design, we report here the synthesis of porphyrin arrays where porphyrins with identical oxidation potentials are directly linked to one another instead of joined via a molecular linker. Oxidative coupling with AgPF(6) of zinc(II)-5,15-bis(4-tert-butylphenyl)-10-phenylporphyrin, obtained by a rational synthesis, afforded the expected dimer joined by a meso-meso linkage and an unexpected trimer joined by meso-meso linkages. For attachment to an electroactive surface we synthesized a meso-linked porphyrin dimer with a thiol-linker in one of the meso positions. The S-acetyl protecting group was used to avoid handling free thiol groups. Coupling of zinc(II)-5,10,15-tris(3, 5-di-tert-butylphenyl)porphyrin ("upper half") and zinc(II)-5-[4-(S-acetylthio)phenyl]-10,20-bis(3, 5-di-tert-butylphenyl)porphyrin ("lower half") afforded three different meso-linked dimers with the desired dimer as the main product. Electrochemical examination of the meso-linked dimer in solution shows that the first two oxidation potentials of the array differ by approximately 0.15 V and straddle the value exhibited by the monomeric constituents. The third and fourth oxidation potentials of the array are also split although to a lesser extent ( approximately 0.08 V) than the first and second. For the meso-linked trimer, the first three oxidation waves are also split; however, these waves are severely overlapped. The electrochemical behavior of the dimers and trimer is indicative of strong electronic interactions among the porphyrins. The thiol-derivatized meso-linked dimers form self-assembled monolayers (SAMs) on gold via in situ cleavage of the S-acetylthio protecting group. The porphyrin SAM exhibits four well-resolved oxidation waves. Regardless, the meso-meso linkage is relatively unstable upon formation of the pi-cation radical(s). This characteristic indicates that the structural motif is of limited utility for molecular information storage elements.     

Synthesis, characterization, and photophysical properties of a free base and a biszinc(II) complex of 1,3-bisporphyrincalix[4]arene: evidence for "tunable intramolecular open and closed conformations"

The bismacrocycle 5,17-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]-25,26,27,28-tetrapropoxycalix[4]arene (4) was synthesized in three steps from the corresponding bisaldehyde 5,17-diformyl-25,26,27,28-tetrapropoxycalix[4]arene. The biszinc(II) complex (5) was prepared as well, and the photophysical properties were measured using 2-MeTHF as solvent at 298 and 77 K. While computer modeling for 5 predicts that both pinched cone conformers, closed (porphyrins near each other) and open (porphyrins away from each other), may exist in the "gas phase", the experimental data indicate clearly that no zinc porphyrin...zinc porphyrin interactions are present in solution at 298 K, favoring the open conformer, where the two macrocycles are placed away from each other. On the other hand, clear evidence for a closed conformer is observed at 77 K. Variable-temperature (1)H NMR experiments show that 5 is fluxional between 298 and 183 K, while 4 keeps the open conformation for the whole temperature range. This behavior is unprecedented for calix[4]areneporphyrin compounds, and the relative porphyrin ring rigidity is postulated to explain this difference.     

Synthesis, characterization, and DNA-binding and -photocleavage properties of water-soluble lanthanide porphyrinate complexes

A series of cationic lanthanide porphyrinate complexes of the general formula [(Por)Ln(H(2)O)(3)](+) (Ln(3+)=Yb(3+) and Er(3+)) were synthesized in moderate yields through the interaction of meso-pyridyl-substituted porphyrin free bases (H(2)Por) with [Ln{N(SiMe(3))(2)}(3)]·x[LiCl(thf)(3)], and the corresponding neutral derivatives [(Por)Ln(L(OMe))] (L(OMe)(-)=[(η(5)-C(5)H(5))Co{P(=O)(OMe)(2)}(3)](-)) were also prepared from [(Por)Ln(H(2)O)(3)](+) by the addition of the tripodal anion, L(OMe)(-), an effective encapsulating agent for lanthanide ions. Furthermore, the water-soluble lanthanide(III) porphyrinate complexes--including [(cis-DMPyDPP)Yb(H(2)O)(3)]Cl(3) (cis-DMPyDPP=5,10-bis(N-methylpyridinium-4'-y1)-15,20-di(phenyl)porphyrin), [(trans-DMPyDPP)Yb(H(2)O)(3)]Cl(3) (trans-DMPyDPP=5,15-bis(N-methylpyridinium-4'-y1)-10,20-di(phenyl)porphyrin), [(TMPyP)Yb(L(OMe))]I(4), and [(TMPyP)Er(L(OMe))]I(4) (TMPyP=tetrakis(N-methylpyridinium-4-y1)porphyrin)--were obtained by methylation of the corresponding complexes with methyl iodide and unambiguously characterized. The binding interactions and photocleavage activities of the water-soluble lanthanide(III) porphyrinate complexes towards DNA were investigated by UV-visible, fluorescence, and near-infrared luminescence spectroscopy, as well as circular dichroism and gel electrophoresis.     

1,1,2,2-tetraaminoethane derivatives: III. Condensation of 2-(Dinitromethylene)imidazolidine-4,5-diol with nitrogen-containing nucleophiles

Condensation of 1,1-diamino-2,2-dinitroethylene with glyoxal and formaldehyde in water solutions at pH 7–8 gave rise to 2-(dinitromethylene)imidazolidine-4,5-diol and 1,1-diamino-N,N′-bis(hydroxymethyl)-2,2-dinitroethylene respectively. Condensation products of 2-(dinitromethylene)imidazolidine-4,5-diol with acetonitrile, benzonitrile, urethane, 3,4-diaminofurazan were isolated. The reaction of 4,5-diacetamido-2-(dinitromethylene) imidazolidine sulfate with water in acetonitrile led to the formation of 2-(dinitromethylene)-5-methyl-1,2,3,3a,4,6a-hexahydroimidazo[4,5-d]imidazole. The dehydration of 2-(dinitromethylene)imidazolidine-4,5-diol in a system H₂SO₄-AcOH provided 2-(dinitromethylene)-2,3-dihydro-1H-imidazol-4-ol. 1,1-Diamino-N,N′-bis(hydroxymethyl)-2,2-dinitroethylene in sulfuric acid was converted into 4-(dinitromethylene)-1,3,5-oxadiazinane.     

Photodynamic efficiency of porphyrins encapsulated in polysilsesquioxanes

Mesoporous organosilica-porphyrin composites were obtained by entrapment of 5,10,15,20-tetraphenylporphyrin (TPP) and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin (TMPyP) into three polysilsesquioxanes prepared by the sol-gel method from 1,2-bis(triethoxysilyl)ethane, 1,6-bis(triethoxysilyl)hexane, and 1,8-bis(triethoxysilyl)octane. The materials were characterised by their texture and optical properties (fluorescence and absorbance) and by light-induced antimicrobial activity against E. coli BL21(DE3) (pET16bDsRed) strain.     

Three-dimensional porous metal-metalloporphyrin framework consisting of nanoscopic polyhedral cages

An unprecedented nanoscopic polyhedral cage-containing metal-metalloporphyrin framework, MMPF-1, has been constructed from a custom-designed porphyrin ligand, 5,15-bis(3,5-dicarboxyphenyl)porphine, that links Cu(2)(carboxylate)(4) moieties. A high density of 16 open copper sites confined within a nanoscopic polyhedral cage has been achieved, and the packing of the porphyrin cages via an "ABAB" pattern affords MMPF-1 ultramicropores which render it selective toward adsorption of H(2) and O(2) over N(2), and CO(2) over CH(4).