Benefits of using BODIPY-porphyrin dyads for developing deep-red lighting sources.

The syntheses, as well as the photophysical and electrochemical characterization, of two novel BODIPY-porphyrin dyads and their first application in lighting schemes are provided. The benefits ascribed to their unique features, namely (i) a good electronic alignment, (ii) a remarkable efficient energy transfer, and (iii) excellent film morphology, lead to deep-red lighting devices with stabilities of around 1000 h and efficiencies of 0.13 Lm W(-1).

Efficient ternary organic photovoltaics incorporating a graphene-based porphyrin molecule as a universal electron cascade material.

A graphene-based porphyrin molecule (GO-TPP) was synthesized by covalent linkage of graphene oxide (GO) with 5-(4-aminophenyl)-10,15,20-triphenyl porphyrin (TPP-NH2). The yielded graphene-based material is a donor-acceptor (D-A) molecule, exhibiting strong intermolecular interactions between the GO core (A) and the covalently anchored porphyrin molecule (D). To demonstrate the universal role of GO-TPP as an electron cascade material, ternary blend organic photovoltaics based on [6,6]-phenyl-C71-butyric-acid-methyl-ester (PC71BM) as an electron acceptor material and two different polymer donor materials, poly[N-9'-hepta-decanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT) and the highly efficient poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7), were fabricated. The addition of GO-TPP into the active layer implies continuous percolation paths between the D-A interfaces, enhancing charge transport, reducing exciton recombination and thus improving the photovoltaic performance of the device. A simultaneous increase of short circuit current density (Jsc), open-circuit voltage (Voc) and fill factor (FF), compared to the PTB7:PC71BM reference cell, led to an improved power conversion efficiency (PCE) of 8.81% for the PTB7:GO-TPP:PC71BM-based device, owing mainly to the more efficient energy level offset between the active layer components.

A triazine di(carboxy)porphyrin dyad versus a triazine di(carboxy)porphyrin triad for sensitizers in DSSCs.

Two porphyrin-chromophores, i.e. triad PorZn-(PorCOOH)(2)-(piper)2 (GZ-T1) and dyad (PorZn)(2)-NMe2 (GZ-T1), have been synthesized and their photophysical and electrochemical properties have been investigated. The optical properties together with the appropriate electronic energy levels, i.e. the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels, revealed that both porphyrin assemblies can function as sensitizers for dye sensitized solar cells (DSSCs). The and -based DSSCs have been prepared and studied using 20 mM CDCA as coadsorbent and were found to exhibit an overall power conversion efficiency (PCE) of 5.88% and 4.56%, respectively (under an illumination intensity of 100 mW cm(-2) with TiO(2) films of 12 µm). The higher PCE of the -sensitized DSSC, as revealed from the current-voltage characteristic under illumination and the incident photon to current conversion efficiency (IPCE) spectra of the two DSSCs, is mainly attributed to its enhanced short circuit current (J(sc)), although both the open circuit voltage (V(oc)) and the fill factor are improved too. The electrochemical impedance spectra (EIS) demonstrated a shorter electron transport time, longer electron lifetime and higher charge recombination resistance for the DSSC sensitized with the dye as well as a larger dye loading onto the TiO(2) surface.

Gadolinium acetylacetonate tetraphenyl monoporphyrinate complex and some of its derivatives: EXAFS study and molecular dynamics simulation.

Many attempts to obtain single crystals appropriate for X-ray diffraction analysis of the Ln(tpp)(acac) derivatives (where Ln = Gd or Sm, tpp = tetraphenylporphyrin and acac = acetylacetonate) have failed so far. A suitable way to get structural parameters for these monoporphyrinates is to use extended X-ray absorption fine structure (EXAFS) spectroscopy. We recorded spectra of the monoporphyrins, Ln(tpp)(acac) and Gd(tpyp)(acac) (where tpyp = tetrapyridylporphyrin), and the bisporphyrin GdH(tpyp)2 in the solid state. We particularly focused our structural analysis on Gd(tpp)(acac), applying both molecular modeling and EXAFS, which allowed us to get accurate results about the local environment of the central atom. The Gd3+ ion of the complex at room temperature was found to be bonded to four monoporphyrin nitrogen atoms at an average distance R(Gd-N(av)) = 2.48 A and to three or four oxygen atoms at R(Gd-O(ac,w)) = 2.38 A from an acetylacetonato anion and a water molecule. The presence of the second water molecule in the coordination sphere was barely discernible by EXAFS analysis. Molecular modeling has provided further information about the coordination core geometry of the Gd(tpp)(acac) monoporphyrinate, including a bishydrated coordination sphere. Also, it has enabled the construction of a 3D structural model on which multiple scattering analyses were attempted. Monte Carlo simulation was used to validate the adjustments. EXAFS spectra analysis was carried out on the derivatives, displaying slight distortions in the lanthanide central-atom coordination geometry.

Spectroscopic and structural study of metal-metal bonded metalloporphyrinic derivatives: the case of rhodium-indium.

The synthesis and spectroscopic characterization of heterometallic porphyrinate derivatives containing rhodium-indium metal-metal bonds are reported. The investigated compounds are represented by the formula [(Porph)RhIn(Porph')], where Porph and Porph' are OEP, TPP, beta-Cl(4)TPP, beta-Cl(8)TPP, or TPyP. UV-Visible spectroscopy of the title complexes confirms the presence of a strong pi-pi interaction between the macrocycles in each derivative and denotes the effect of the nontransition metal in their optical features. For comparison purposes, a new bimetallic complex with a rhodium-thallium metal-metal bond is also presented. According to (1)H and (13)C NMR data, we were able to distinguish two major NMR regions: the endo- between the metal-metal bonded macrocycles and the exo-, which are characteristic features of porphyrinic complexes at very close proximity. X-ray absorption spectroscopy (XAS) structural characterization of Rh-In bond was performed on the [(OEP)RhIn(OEP)] complex, in the fluorescence mode, and we essentially focused on the metal-metal distance determination. Finally, the distance of 2.543(3) A was deduced from the X-ray structure of a new [(TPP)RhIn(TPyP)] derivative.

Efficient biomimetic catalytic epoxidation of polyene polymers by manganese porphyrins.

Two polyene polymers, cis-polybutadiene and cis-polyisoprene, were transformed into polyepoxides under mild conditions. The epoxidation of these two polyene polymers is stereospecific, giving cis-epoxides as products. All factors controlling the reaction rate, such as the nature of the catalyst, the oxygen donor and the presence of bases as axial ligands, were studied. The optimum results were obtained when iodosylbenzene was used as the oxygen donor, Mn(TpFPP)Cl as the catalyst and imidazole as the axial ligand. Under these optimum conditions the turnover number was found to be 71. These results render this system promising for the epoxidation of polyene polymers in a more general way.

Comparative study of structure-properties relationship for novel beta-halogenated lanthanide porphyrins and their nickel and free bases precursors, as a function of number and nature of halogens atoms.

The synthetic route of partially beta-halogenated via a "metal-assisted" reaction and perhalogenated terbium complexes is described. This protocol allows the facile insertion of the halogens (bromines or chlorides) to the porphyrin peripheral positions. The electronic absorption spectra and the redox potentials of the free porphyrins as well as the terbium complexes are dramatically affected as the number of halogen atoms increase. In fact, two antagonistic effects are responsible for that, the inductive and the distortion effects on the porphyrin ring. They result in a red shift for the Soret band and a stabilization/destabilization of the HOMOs/LUMOs which in turn is manifested by variations on the redox potentials. The novel crystal structure of the Ni(Cl(8)TPP) is discussed in great detail and compared with the previously reported structures of Tb(Cl(8)TPP) (OAc)(DMSO)(2) x 3PhCH(3) x MeOH and H(2)(Br(8)TPP), as well as with other perhalogenated nickel porphyrins available in the literature.

XAFS study of gadolinium and samarium bisporphyrinate complexes.

The comparative X-ray absorption spectroscopy study of gadolinium and samarium bisporphyrinate complexes represented by the formulas Gd(III)H(oep)(tpp), Gd(III)(oep)(2), Gd(III)H(tpp)(2) and Sm(III)H(oep)(tpp), Sm(III)(oep)(2), Sm(III)H(tpp)(2) is reported. The XAFS spectra are recorded on the LURE-DCI storage ring (Orsay, France) in transmission mode on the microcrystalline samples at the Gd and Sm L(3) edges. The local environment for Ln(3+) ions has been reconstructed applying one-shell and two-shell XAFS analysis procedures. The protonated and nonprotonated bisporphyrinate complexes present different XAFS features. After our analysis on the title derivatives, the gadolinium ion (at 80 K) is found to be bonded: (i) to eight nitrogen atoms at R(Gd-N) 2.50 A, for Gd(III)(oep)(2) [Debye-Waller (DW) factor 0.004 A(2)]; (ii) to seven nitrogen atoms at R(Gd-N) 2.49 A, for Gd(III)H(oep)(tpp) [DW factor 0.005 A(2)] and one nitrogen at long distance; and (iii) to six nitrogen atoms at R(Gd-N) 2.50 A [DW factor 0.006 A(2)] and two nitrogen atoms at long distance for Gd(III)H(tpp)(2). A similar coordination sphere has been detected for the corresponding Sm derivatives. So, the samarium ion (at room temperature) is bonded: (i) to eight nitrogen atoms at R(Sm-N) 2.53 A, for Sm(III)(oep)(2) [DW factor 0.006 A(2)]; (ii) to seven nitrogen atoms at R(Sm-N) 2.53 A, for Sm(III)H(oep)(tpp) [DW factor 0.006 A(2)] and one nitrogen at long distance; and (iii) to six nitrogen atoms at R(Sm-N) 2.50 A, for Sm(III)H(tpp)(2) [DW factor 0.006 A(2)] and two nitrogen atoms at long distance. As far as concerns Ln(III)(oep)(2) complexes, the increase of Ln-N distance in the series Gd(3+) < Eu(3+) < Sm(3+) reflects an increase in the ionic radii, which are in good agreement with previously published XRD data on Eu(III)(oep)(2). Moreover, the protonated Ln(III)H(oep)(tpp) and Ln(III)H(tpp)(2) complexes possess systematically shorter distances of about 0.02 A between the XAFS and XRD data. This difference is attributed to the asymmetry of the distribution concerning Ln-N distances.

Chloro(2,3,7,8,12,13,17,18-octaethylporphinato)gallium(III).

The crystal structure of [Ga(C36H44N4)Cl].1.45CH2C(l)2 has been determined. Examination of the crystal established a two-molecule triclinic unit cell with space group P1. The asymmetric unit contains one porphyrin molecule and two solvate molecules, one as an approximate half molecule with required inversion symmetry. All measurements were made at 127(2) K. The average Ga-N distance is 2.035(4) A and the axial Ga-Cl distance 2.240(1) A. The displacement of the Ga atom from the N4 porphyrin plane is 0.40 A.

Photophysical characterization of hematoporphyrin incorporated within collagen gels.

Physical properties of hematoporphyrin-enriched collagen gels relevant to the photodynamic treatment of cancer are characterized. The incorporation of the sensitizer within the gels does not affect either the structure of the gel or the absorption and fluorescence spectra of the sensitizer. The gel-embedded sensitizer photodegrades efficiently with the formation of a product emitting near 635 nm. Differences in the collagen scattering are observed following sensitization vs. prolonged irradiation with Ar+ laser, indicating contrasting structural modifications effected to the biopolymer matrix in the two cases. The results correspond well to in vivo observations, suggesting that hematoporphyrin-enriched collagen gels may be appropriate systems for modeling the influence of the semisolid nature of tissues, and in particular of the tumour stroma collagen, on the photodynamic phenomenon.