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

The low-lying electronic states and ultrafast relaxation dynamics of the monomers and J-aggregates of meso-tetrakis (4-sulfonatophenyl)-porphyrins

The electronic and vibrational spectra of the meso-tetrakis(4-sulfonatophenyl)-porphyrins (TSPP) have been studied computationally using the PFD-3B functional with time-dependent density functional theory for the excited states. The calculated UV-vis absorption and emission spectra in aqueous solution are in excellent agreement with the experimental measurements of both H2TSPP-4 (monomer) at high pH and H4TSPP-2 (forming J-aggregate) at low pH. Moreover, our calculations reveal an infrared absorption at 1900 cm-1 in the singlet and triplet excited states that is absent in the ground state, which is chosen as a probe for transient IR absorption spectroscopy to investigate the vibrational dynamics of the excited state. Specifically, the S2 to S1 excited state internal conversion process time, the S1 state vibrational relaxation time, and the lifetime of the S1 excited electronic state are all quantitatively deduced.

Low Blue Dose Photodynamic Therapy with Porphyrin-Iron Oxide Nanoparticles Complexes: In Vitro Study on Human Melanoma Cells

The purpose of this study was to investigate the effectiveness in photodynamic therapy of iron oxide nanoparticles (γ-Fe2O3 NPs), synthesized by laser pyrolysis technique, functionalized with 5,10,15,20-(Tetra-4-sulfonatophenyl) porphyrin tetraammonium (TPPS) on human cutaneous melanoma cells, after only 1 min blue light exposure. The efficiency of porphyrin loading on the iron oxide nanocarriers was estimated by using absorption and FTIR spectroscopy. The singlet oxygen yield was determined via transient characteristics of singlet oxygen phosphorescence at 1270 nm both for porphyrin functionalized nanoparticles and rose bengal used as standard. The irradiation was performed with a LED (405 nm, 1 mW/cm2) for 1 min after melanoma cells were treated with TPPS functionalized iron oxide nanoparticles (γ-Fe2O3 NPs_TPPS) and incubated for 24 h. Biological tests revealed a high anticancer effect of γ-Fe2O3 NPs_TPPS complexes indi-cated by the inhibition of tumor cell proliferation, reduction of cell adhesion, and induction of cell death through ROS generated by TPPS under light exposure. The biological assays were combined with the pharmacokinetic prediction of the porphyrin.

Photoelectrochemical Stability under Anodic and Cathodic Conditions of Meso-Tetra-(4-Sulfonatophenyl)-Porphyrinato Cobalt (II) Immobilized in Polypyrrole Thin Films

Cobalt porphyrins have emerged as promising catalysts for electrochemical and photoelectrochemical applications because of their good performance, low cost and the abundance of cobalt in the earth. Herein, a negatively charged porphyrin meso-tetra-(4-sulfonatophenyl)-porphin (TPPS) was immobilized in polypyrrole (PPy) during the electro-polymerization, and then it was metallized with cobalt to obtain meso-tetra-(4-sulfonatophenyl)-porphyrinato cobalt (II) (CoTPPS) as a dopant in PPy. The coatings were evaluated as photoelectrodes towards thiosulfate oxidation and oxygen reduction. For comparison purposes, the photoelectrochemical behavior of ClO₄⁻-doped polypyrrole films was also evaluated. Characterizations by chronoamperometry, UV-Vis spectroscopy and Raman spectroscopy showed that polypyrrole is stable under anodic and cathodic conditions, but CoTPPS and TPPS immobilized in PPy are degraded during the anodic process. Thus, decreases in photocurrent of up to 87% and 97% for CoTPPS-doped PPy and TPPS-doped PPy were observed after a 30-min chronoamperometry test. On the other hand, good stability of CoTPPS and TPPS immobilized in PPy was observed during photoelectrochemical oxygen reduction, which was reflected in almost constant photocurrents obtained by chronoamperometry. These findings are relevant to understanding the role of CoTPPS as a catalyst or pre-catalyst in photoelectrochemical applications such as water splitting. In addition, these results could pave the way for further research to include CoTPPS-doped PPy in the design of novel photocathodes.

A putative heme manganese(v)-oxo species in the C–H activation and epoxidation reactions in an aqueous buffer

Synthesis and reactivity studies of manganese(v)-oxo species in the C–H activation of alkyl hydrocarbons and epoxidation of cyclohexene in aqueous conditions are investigated.

5-Phenyl-10,15,20-Tris(4-sulfonatophenyl)porphyrin: Synthesis, Catalysis, and Structural Studies

A convenient protocol for the preparation of 5-phenyl-10,15,20-tris(4-sulfonatophenyl)porphyrin, a water-soluble porphyrin with unique aggregation properties, is described. The procedure relies on the one-pot reductive deamination of 5-(4-aminophenyl)-10,15,20-tris(4-sulfonatophenyl)porphyrin, that can be in turn easily obtained from 5,10,15,20-tetraphenylporphyrin by a known three-step sequence involving mononitration, nitro to amine reduction and sulfonation of the phenyl groups. This method provides the title porphyrin in gram scale, and compares very favorably with the up to now only described procedure based on the partial sulfonation of TPP, that involves a long and tedious chromatographic enrichment of the final compound. This has allowed us to study for the first time both the use of its zwitterionic aggregate as a supramolecular catalyst of the aqueous Diels⁻Alder reaction, and the morphology of the aggregates obtained under optimized experimental conditions by atomic force microscopy and also by transmission electron cryomicroscopy.

Vibrational structure analysis of cobalt fluoro-porphyrin surface coatings on gallium phosphide

Grazing angle attenuated total reflectance Fourier transform infrared (GATR–FTIR) spectroscopy is used to characterize chemically modified gallium phosphide (GaP) surfaces containing grafted cobalt(II) porphyrins with 3-fluorophenyl substituents installed at the meso-positions. In these hybrid constructs, porphyrin surface attachment is achieved using either a two-step method involving coordination of cobalt fluoro-porphyrin metal centers to nitrogen sites on an initially applied thin-film polypyridyl surface coating, or via a direct modification strategy using a cobalt fluoro-porphyrin precursor bearing a covalently bonded 4-vinylphenyl surface attachment group at a [Formula: see text]-position. Both surface-attachment chemistries leverage the UV-induced immobilization of alkenes but result in distinct structural connectivities of the grafted porphyrin units and their associated vibrational spectra. In particular, the in-plane deformation vibrational frequency of metalloporphyrin components in samples prepared via coordination to the polymeric interface is characterized by an eight wavenumber shift to higher frequencies compared to that measured on metalloporphyrin-modified surfaces prepared using the one-step attachment method. The more rigid ring structure in the polymeric architecture is consistent with coordination of porphyrin cobalt centers to pyridyl-nitrogen sites on the surface graft. These results demonstrate the use of GATR–FTIR spectroscopy as a sensitive tool for characterizing porphyrin-modified surfaces with absorption signals that are close to the detection limits of many common spectroscopic techniques.

Practicably efficient ethylbenzene oxidation catalyzed by manganese tetrakis(4-sulfonatophenyl)porphyrin grafted to powdered chitosan

Manganese tetrakis(4-sulfonatophenyl)porphyrin chloride was grafted onto powdered chitosan via an acid–base reaction and ligation. The grafted catalyst was characterized by transmission electron microscopy, ultraviolet and visible spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectrometry and thermogravimetry. Ethylbenzene oxidation with O[Formula: see text] by the catalyst in the absence of additives and solvents can achieve moderate yields (approximately 30%) of acetophenone and phenethyl alcohol. The grafted catalyst can be reused four times for oxidation reactions. The results indicate that the catalytic activity of manganese tetrakis(4-sulfonatophenyl)porphyrin chloride is promoted by the ligation and grafting function of the amino groups in the powdered chitosan.

Porphyrin-Gold Nanomaterial for Efficient Drug Delivery to Cancerous Cells

With an aim to overcome multidrug resistance (MDR), nontargeted delivery, and drug toxicity, we developed a new nanochemotherapeutic system with tetrasodium salt of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) armored on gold nanoparticles (TPPS-AuNPs). The nanocarrier is able to be selectively internalized within tumor cells than in normal cells followed by endocytosis and therefore delivers the antitumor drug doxorubicin (DOX) particularly to the nucleus of diseased cells. The embedment of TPPS on the gold nanosurface provides excellent stability and biocompatibility to the nanoparticles. Porphyrin interacts with the gold nanosurface through the coordination interaction between gold and pyrrolic nitrogen atoms of the porphyrin and forms a strong association complex. DOX-loaded nanocomposite (DOX@TPPS-AuNPs) demonstrated enhanced cellular uptake with significantly reduced drug efflux in MDR brain cancer cells, thereby increasing the retention time of the drug within tumor cells. It exhibited about 9 times greater potency for cellular apoptosis via triggered release commenced by acidic pH. DOX has been successfully loaded on the porphyrin-modified gold nanosurface noncovalently with high encapsulation efficacy (∼90%) and tightly associated under normal physiological conditions but capable of releasing ∼81% of drug in a low-pH environment. Subsequently, DOX-loaded TPPS-AuNPs exhibited higher inhibition of cellular metastasis, invasion, and angiogenesis, suggesting that TPPS-modified AuNPs could improve the therapeutic efficacy of the drug molecule. Unlike free DOX, drug-loaded TPPS-AuNPs did not show toxicity toward normal cells. Therefore, higher drug encapsulation efficacy with selective targeting potential and acidic-pH-mediated intracellular release of DOX at the nucleus make TPPS-AuNPs a "magic bullet" for implication in nanomedicine.

Poly(carboxylic acid)-Cyclodextrin/Anionic Porphyrin Finished Fabrics as Photosensitizer Releasers for Antimicrobial Photodynamic Therapy

In the development of new antibacterial therapeutic approaches to fight multidrug-resistant bacteria, antimicrobial photodynamic therapy (aPDT) represents a well-known alternative to treat local infections caused by different microorganisms. Here we present a polypropylene (PP) fabric finished with citrate-hydroxypropyl-βCD polymer (PP-CD) entrapping the tetra-anionic 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (TPPS) as photosensitizer-eluting scaffold (PP-CD/TPPS) for aPDT. The concept is based on host-guest complexation of porphyrin in the cavities of CDs immobilized on the PP fibers, followed by its sustained and controlled delivery in release medium and simultaneous photoinactivation of microorganisms. Morphology of fabric was characterized by optical (OM) and scanning electron microscopies (SEM). Optical properties were investigated by UV-vis absorption, steady- and time-resolved fluorescence emission spectroscopy. X-ray photoelectron spectroscopy (XPS) and FT-IR revealed the surface chemical composition and the distribution map of the molecular components on the fabric, respectively. Direct ¹O₂ determination allowed to assess the potential photodynamic activity of the fabric. Release kinetics of TPPS in physiological conditions pointed out the role of the CD cavity to control the TPPS elution. Photoantimicrobial activity of the porphyrin-loaded textile was investigated against both Gram-positive Staphylococcus aureus ATCC 29213 (S. aureus) and Gram-negative Pseudomonas aeruginosa ATCC 27853 (P. aeruginosa). Optical microscopy coupled with UV-vis extinction and fluorescence spectra aim to ascertain the uptake of TPPS to S. aureus bacterial cells. Finally, PP-CD/TPPS fabric-treated S. aureus cells were photokilled of 99.98%. Moreover, low adhesion of S. aureus cells on textile was established. Conversely, no photodamage of fabric-treated P. aeruginosa cells was observed, together with their satisfying adhesion.

Resonance Raman spectroscopy study of protonated porphyrin

Resonance Raman microscopy was used to study the resonance Raman scattering of the diacid (diprotonated form) of free-base porphyrin (21H,23H-porphine) in a crystal powder and KBr pellets. Intensive lines in the spectral range between 100÷1000cm^-1 have been detected and assigned as spectral manifestation of out-of-plane modes. The Raman spectra were simulated by means of DFT methods and compared with the experimental data. It is evident from experimental and theoretical results that the activation of out-of-plane modes arises from saddle distortion of the porphyrin macrocycle upon formation of its diprotonated form.

Combined use of optical spectroscopy and computational methods to study the binding and the photoinduced conformational modification of proteins when NMR and X-ray structural determinations are not an option

The functions of proteins depend on their interactions with various ligands and these interactions are controlled by the structure of the polypeptides. If one can manipulate the structure of proteins, their functions can in principle be modulated. The issue of protein structure-function relationship is not only a central problem in biophysics, but is becoming clear that the ability to "artificially" modify the structure of proteins could be relevant in fields beyond the biomedical area to provide, for instance, light responses in proteins which would not possess such properties in their native state. This chapter presents an overview of the combination of optical electronic and vibrational spectroscopy with various computational methods to investigate the binding between photoactive ligands and proteins.

Resonance Raman and vibrational mode analysis used to predict ligand geometry for docking simulations of a water soluble porphyrin and tubulin

The ability to modify the conformation of a protein by controlled partial unfolding may have practical applications such as inhibiting its function or providing non-native photosensitive properties. A water-soluble porphyrin, meso-tetrakis (p-sulfonatophenyl) porphyrin (TSPP), non-covalently bound to tubulin can be used as a photosensitizer, which upon irradiation can lead to conformational changes of the protein. To fully understand the mechanism responsible for this partial unfolding and determine the amino acid residues and atoms involved, it is essential to find the most likely binding location and the configuration of the ligand and protein. Techniques typically used to analyze atomic position details, such as nuclear magnetic resonance and X-ray crystallography, require large concentrations, which are incompatible with the dilute conditions required in experiments for photoinduced mechanisms. Instead, we develop an atomistic description of the TSPP-tubulin complex using vibrational mode analysis from density functional theory calculations correlated to resonance Raman spectra of the porphyrin paired with docking simulations. Changes in the Raman peaks of the porphyrin molecule correlate with changes in its structural vibrational modes when bound to tubulin. The data allow us to construct the relative geometry of the porphyrin when bound to protein, which are then used with docking simulations to find the most likely configuration of the TSPP-tubulin complex.

Comparative study of the structural and vibroelectronic properties of porphyrin and its derivatives

Density functional theory (DFT and time-dependent-DFT (TD-DFT) were employed to investigate the vibroelectronic structural properties of porphyrin and some derivatives: unsubstituted porphyrin (TPyr), meso-tetraphenylporphyrin (TPP), meso-tetrakis(p-sulfonatophenyl)porphyrin (TSPP), protonated-TPyr (H₂TPyr), deuterated-H₂TPyr (D₄TPyr), protonated-TPP (H₂TPP) and deuterated-H₂TPP (D₄TPP), protonated TSPP (H₂TSPP), deuterated-H₂TSPP (D₄TSPP), dicationic TSPP (H₆TSPP) and deuterated-H₆TSPP (D₈TSPP). The possible internal conversion (IC) and intersystem crossing (ISC) processes of these compounds were investigated. Finally, the relaxed ground state potential energy surface (PES) (S₀), and singlet (S_n, n = 1–24) and triplet (T_n) excited state PESs of the TSPP molecule were calculated as function of the dihedral angle (C_α-C_m-C_ϕ-C(ph)) rotation. The results of the calculations indicated that while the meso-substitutions caused a significant shift in frequencies when the meso-carbons within the parent-porphine (or TPyr) are involved in the vibrational motion of molecules; the protonation of the N atoms at the porphine/porphyrin core causes a significant blue shift when the H on the N atoms within the pyrroline are dominantly involved in the vibrational motions. The deuteration of N atoms not only caused a red-shift in the frequencies of the corresponding peaks below 1600 cm⁻¹, but also produced new vibrational modes of frequencies in the 2565–2595 cm⁻¹ range caused by the N-D bond stretching. Similarly, the deuteration of O atoms within the sulfonato groups (-SO₃⁻) exhibited a new peak at around 2642 cm⁻¹ due to O-D bond stretching. The measured Raman spectrum of the H₂TSPP is assigned based on the predicted Raman spectra of the compounds studied here and measured Raman spectrum of the TPP (from our previous work). The IR spectrum is assigned based on our calculations and measured IR spectra obtained from the literature. The results of the TD-DFT calculations did not only indicate that the meso-substitution and protonation of the porphyrin bring about a significant read shift in the electronic transitions; but also provided a strong evidence for the IC from the Soret band to Q-bands beside possibility of the ISC process; its existence depend on the other excited state process such as much faster vibrational relaxation; the IC and etc. The ground state PES curve (S₀) of the ionic TSPP exhibited two minima at the dihedral angle (C_α-C_m-C_ϕ-C) of about 66° (corresponds to the lowest ground state) and 110° (corresponds to next energetically stable state or the local minima). The energy deference between these two minima is 0.0132 eV (or 106 cm⁻¹) and the highest potential energy barrier when undergoing from the lowest ground state to this local state is only 0.0219 eV (177 cm⁻¹; which is compatible with the thermal energy (kT) at 298 K is 207.2 cm⁻¹.

Electronic absorption, MCD, and luminescence properties of porphyrin J-aggregates

In this paper, we have investigated electronic absorption, magnetic circular dichroism, fluorescence, and phosphorescence spectra for a protonated form of H 2 TPPS 4( H 4 TPPS 4) and the J-aggregates of H 4 TPPS 4. The J-aggregation induces a large red-shift in the B (Soret) and Q absorption bands, while the phosphorescence peaks of H 4 TPPS 4 and its J-aggregates are almost entirely similar. The large red-shift of the B-band is quantitatively explained by the exciton interactions. Thus, the exciton interactions in the J-aggregates are proposed as a useful approach to decrease the energy splitting between the fluorescent and phosphorescent states.

Synthesis of 1:2 molecular complexes between free base meso-tetraarylporphyrins and sulfur trioxide

The interaction of meso-tetraarylporphyrins, H 2 T (4- X ) PP , with sulfur trioxide pyridine complex ( SO 3. py ) in chloroform only produced 1:2 molecular complexes, [ H 2 T (4- X ) PP ( SO 3)2]. UV-vis, 1 H NMR, and FT-IR spectra, as well as elemental analysis, suggested pseudo tetrahedrally distorted porphyrin core structures with σ-bonding from two pyrrolenine nitrogen donors to the d orbital of sulfur in two SO 3 s and the occurrence of two hydrogen bonds between two pyrrolic NH and oxygens of sulfur trioxides from above and below the mean plane of the porphyrins.

Synthesis and photocatalytic hydrogen evolution of meso-tetrakis(p-sulfonatophenyl)porphyrin functionalized platinum nanocomposites

Meso-tetrakis(p-sulfonatophenyl)porphyrin (TPPS4) functionalized platinum nanocomposites were synthesized and characterized using ultraviolet-visible absorption spectroscopy (UV-vis), fluorescence spectroscopy (FL), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray diffraction (XRD) methods. The postulated configuration of TPPS4 functionalized platinum nanocomposite may be described as an antenna system containing a photoreceptive TPPS4 shell and a nanosize platinum core. Fluorescence and photoelectrochemistry studies of both TPPS4 and the platinum nanocomposites showed that efficient electron/energy transfer occurred from the TPPS4 donor to the metallic nanocore acceptor. TPPS4 functionalized platinum nanocomposites are photocatalytic active for water reduction to produce hydrogen. The turnover numbers (TONPt and TONTPPS4) and quantum yield of hydrogen (ϕH2) for the photocatalyst (nPt:nTPPS4= 250) were 44, 11056, and 1.8%, respectively, calculated on the basis of the total amount of H2 evolution for 12 h irradiation.

Characterization of sulfonated phthalocyanines by mass spectrometry and capillary electrophoresis

We report the characterization of sulfonated phthalocyanines using capillary electrophoresis and mass spectrometry. Derivatives investigated included the copper, cobalt, zinc and metal-free sulfonated phthalocyanines. In general, sulfonated phthalocyanines were found as aggregates in capillary electrophoresis separations, even at low concentration. Separations were much better at pH 9.0 than at pH 2.5. The addition of β-cyclodextrin did not alter the electropherograms significantly. The electropherograms of commercially available copper phthalocyanine-3,4',4″,4‴-tetrasulfonic acid and 4,4',4″,4‴-tetrasulfonic acid were very different, consistent with the latter compound having a structure that is not fully sulfonated. Matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) were used to characterize the sulfonated phthalocyanines. In general, MALDI gave better results than ESI. Mass spectral evidence was obtained for a pentasulfonated species of both the metal-free phthalocyanine and zinc phthalocyanine when these species were made by sulfonation of the metal-free phthalocyanine (followed by zinc insertion in the latter case). Sulfonated tetraphenylporphyrin derivatives were used as standards for mass spectrometry and to estimate the effect of net charge on the capillary electrophoresis migration time for sulfonated tetrapyrroles. Clean separation of the sulfonated tetraphenylporphyrin derivatives [5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4), 5,10,15-tris(4-sulfonatophenyl)-20-phenylporphyrin (TPPS3) and 5,10-bis(4-sulfonatophenyl)-15,20-diphenylporphyrin (TPPS2a)] was observed by capillary electrophoresis.

Molecular interactions of monosulfonate tetraphenylporphyrin (TPPS1) and meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) with dimethyl methylphosphonate (DMMP)

The molecular interactions of monosulfonate tetraphenylporphyrin (TPPS(1)) and meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) with dimethyl methylphosphonate (DMMP) have been investigated by UV-vis and fluorescence spectroscopies. The association constants and interaction stoichiometries of the bindings were obtained through Benesi-Hildebrand (B-H) method. Particularly, both linear and nonlinear fitting procedures were performed to evaluate the possible 1:2 interactions. Experimental results showed that hydrogen-bonding interactions existed in both of the two systems, resulting in regular changes in the absorbance and fluorescence characteristics of the porphyrins. The association constants and stoichiometries determined from absorbance and fluorescence studies were in excellent agreement. Using a nonlinear fitting method, we demonstrated that the one-step 1:2 interaction took place in the TPPS(1)-DMMP system, and the association constants were determined to be 71.4 M(-1) by absorbance measurements and 70.92 M(-1) by fluorescence measurements. The interaction stoichiometry of the TPPS-DMMP system was 1:1, and the association constants were determined to be 16.06 M(-1) by absorbance measurements and 16.03 M(-1) by fluorescence measurements. It was concluded that the interaction between TPPS(1) and DMMP was stronger than that between TPPS and DMMP.

Solvent effects on the absorption, circular dichroism and Raman spectroscopy of meso-tetrakis [3-methoxy-4-(N-carbazyl)n-hexyloxyphenyl] porphyrin in water-THF solution

Solutions of meso-tetrakis [3-methoxy-4-(N-carbazyl)n-hexyloxyphenyl] porphyrin (4C6-TPP) in a water-organic mixture (tetrahydrofuran, THF) generate aggregates with absorption spectra characterized by broader red shifts of the Soret band relative to the monomeric porphyrin band. For the aggregated form several phenyl modes enhance and some modes weaken, the nu(2), nu(3) and nu(11) bands in the Raman spectra are slightly downshifted compared with the monomeric form. These data suggest that the phenyl groups of 4C6-TPP in the aggregate rotate to an orientation more coplanar with the porphyrin core. The increased conjugation of the meso-phenyl rings with the porphyrin core brings about the red shift of the Soret band. The circular dichroism (CD) band of the aggregate undergoes some changes with time, as indicated by the transition from a negative band to no signal resulted from the rotation of phenyl groups. All of the results imply that the location of the phenyl groups plays a key role in the determination of the morphology of the aggregate.

The effects of pH and ionic strength on topical delivery of a negatively charged porphyrin (TPPS4)

Meso-tetra-[4-sulfonatophenyl]-porphyrin (TPPS(4)) is a charged porphyrin derivate used in photodynamic therapy (PDT) by parenteral administration. This study means to investigate potential enhancement for its topical delivery by determining the TPPS(4) dependence on the environmental characteristics and applying iontophoresis. In order to accomplish this task, cathodal and anodal iontophoresis as well as passive delivery of the drug were studied in vitro and in vivo in function of its concentration, pH and ionic strength. A reduction in drug concentration as well as the NaCl elimination from donor formulation at pH 2.0 increased TPPS(4) passive permeation through the skin in vitro. Iontophoresis improved TPPS(4) delivery across the skin when applied in solutions containing NaCl at pH 2.0, regardless electrode polarity. However, at pH 7.4, the amount of TPPS(4) permeated by iontophoresis was not different from that one permeated after passive experiments from a solution containing NaCl. Despite the fact that iontophoresis did not improve TPPS(4) transdermal delivery at this specific condition, in vivo experiments showed that 10 min of iontophoresis quickly and homogeneously delivered TPPS(4) to deeper skin layers when compared to passive administration, which is an important condition for topical treatment of skin tumors with PDT.

Density functional theory studies on the electronic and vibrational spectra of octaethylporphyrin diacid

The ground-state structure and electronic and vibrational spectra of octaethylporphyrin diacid (H4OEP2+) have been studied with the density functional theory. The geometrical parameters computed with B3LYP, PBE1PBE and mPW1PW91 functionals and 6-31G* basis sets are well consistent with the experimental values. Electronic absorption spectrum of H4OEP2+ has been studied with the time-dependent DFT method, and the calculated excitation energies and oscillator strengths are compared with the experimental results. The Raman and IR spectra of H4OEP2+ and the Raman spectrum of its N-deuterated analogue (D4OEP2+) were measured. The observed Raman and IR bands have been assigned based on the frequency calculations at the B3LYP/6-31G* level of theory.

Interaction of meso-tetrakis(4-sulphonatophenyl)porphine with chitosan in aqueous solutions

Interaction of meso-tetrakis(4-sulphonatophenyl)porphine (TPPS4) with chitosan (Mr approximately 400 kDa, N-acetyls approximately 20 mol.%) was studied in aqueous solutions. UV-vis absorption and circular dichroism (CD) spectroscopic titration of 10 micromol l-1 TPPS4 with chitosan demonstrated that an addition of the polysaccharide at appropriate concentrations and pH values induce and support self-aggregation of the macrocycles. The mode of aggregation was strongly dependent on pH: stacking (H-type) aggregates predominated at weak acidic conditions (pH 4.8-6.8) and tilted (J-type) aggregates at pH 2.5. At the intermediate pH value (3.6) both types of TPPS4 aggregates were detected. High amount of chitosan (>0.05 mmol l-1 of GlcN) disrupts H-aggregates forming monomeric porphyrin-chitosan complexes (pH 3.6-6.8), while J-aggregates (pH 2.5) are stable even at very high chitosan concentrations. CD titration experiments confirmed the formation of optically active species of TPPS4 in the presence of chitosan. The complex nature of CD bands assigned to both types of porphyrin aggregates indicated the occurrence of several chiral macrocyclic species dependently on pH value and chitosan concentration.

Resonance Raman study of free-base tetraphenylporphine and its dication

Resonance Raman spectra of free-base tetraphenylporphine and its dication obtained with 441.6, 476.5, 488.0 and 514.5 nm excitation lines in the frequency region 100-1625 cm(-1) are reported. Some bands due to in-plane and out-of-plane vibrational modes, which are symmetry forbidden under ideal D(2h), are also seen in the Raman spectra of these molecules. These bands arise due to dynamic and/or static coupling of out-of-plane modes with the allowed in-plane modes. Dynamic coupling may be facilitated by the proton tunneling, while static coupling is due to out-of-plane distortion in the geometrical structure of the molecule. Shift in the positions for certain bands in the Raman spectra of dication are interpreted on the basis of electronic changes due to sharing of electrons of the B(1u) orbital by the two added protons.

Density functional theory studies on the Raman and IR spectra of meso-tetraphenylporphyrin diacid

The vibrational spectra of meso-tetraphenylporphyrin diacid (H4TPP2+) have been studied with the density functional theory. Raman and IR spectra of H4TPP2+ and its N-deuterated analogue (D4TPP2+) are measured and compared with the computational results. Complete assignments of observed IR and Raman bands were proposed on the bases of calculation results. The DFT calculations reproduce 140 observed fundamentals with the RMS 8.6 cm-1. The computational as well as the experimental results reveal that the saddle-distortion of porphyrin macrocycle for the diacid leads to a significant effect on its vibrational spectra. Especially, several out-of-plane skeletal modes, which were either unobserved or very weak in the Raman spectra of CuTPP and H2TPP, are activated in the Raman spectra of the diacids. In addition, enhancement for the Raman bands of phenyl CC stretching modes were observed and attributed to the conjugation effect of pi-systems of the phenyl and the porphyrinato macrocycles.

Infrared spectroscopic studies of free-base tetraphenylporphine and its dication

We present here the infrared absorption spectra of free-base tetraphenylporphine and its dication. Most of the allowed IR bands of porphyrin skeletal are observed in pairs due to two-fold symmetry of the free-base tetraphenylporphine. Observation of some new bands, disappearance of few bands in the IR spectrum of dication are interpreted on the basis of point group symmetry S4. Intensity change in the observed bands due to vibrational motion of the phenyl rings for dication is also explained on the basis of symmetry of dication. Sharing of electrons of the B(1u) orbitals by the two added protons are responsible for the shifts in the position of certain IR bands for dication.

Anodic electrodeposition of NiTSPP from aqueous basic media

The oxidative electrodeposition of NiTSPP (tetrakis(4-sulfonatophenyl) Ni porphyrin) on ITO electrode from 0.1 M NaOH aqueous solution has been studied, and UV-visible and reflection FTIR spectroscopies have been used to analyze the composition of such film. By use of UV-vis spectroscopy, small absorbance of the film and an almost nulling effect on the Soret band of the porphyrin along the Ni(III)/Ni(II) redox process were observed. The reflection FTIR spectroscopy detected the presence of Ni-OH groups in the reduced film and as well the state of the porphyrin molecules as radical cation. Moreover, the porphyrin has been quantified by means of the area of the vibration bands assigned to the sulfonate groups by using as reference a Langmuir-Blodgett film containing a known surface concentration of NiTSPP. These results lead us propose the formation of a conductor salt by electrocrystallization, with stoichiometries TSPP/Ni(II)(OH)2 and TSPP/Ni(III)OOH, for its reduced and oxidized forms, respectively. In these two forms, the porphyrin rings will be present as radical cation, which may be stabilized through its dimerization or polymerization.