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Metalloporphyrins are highly recognized for their capacity to act as sensitive substances used in formulation of optical, fluorescent, and electrochemical sensors. A novel compound, namely Pt(II)-5,10,15,20-tetra-(4-allyloxy-phenyl) porphyrin, was synthesized by metalation with PtCl2(PhCN)2 of the corresponding porphyrin base and was fully characterized by UV-vis, fluorimetry, FT-IR, 1H-NMR, and 13C-NMR methods. The fluorescence response of this Pt-porphyrin in the presence of different concentrations of hydrogen peroxide was investigated. Besides, modified glassy carbon electrodes with this Pt-porphyrin (Pt-Porf-GCE) were realized and several electrochemical characterizations were comparatively performed with bare glassy carbon electrodes (GCE), in the absence or presence of hydrogen peroxide. The Pt-porphyrin demonstrated to be a successful sensitive material for the detection of hydrogen peroxide both by fluorimetric method in a concentration range relevant for biological samples (1.05&ndash, 3.9 &times, 10&minus, 7 M) and by electrochemical method, in a larger concentration range from 1 &times, 6 M to 5 &times, 5 M. Based on different methods, this Pt-porphyrin can cover detection in diverse fields, from medical tests to food and agricultural monitoring, proving high accuracy (correlation coefficients over 99%) in both fluorimetric and electrochemical measurements.

The developments concerning new hybrids based on porphyrin derivatives and colloids destined for the detection of ascorbic acid (AA) in the relevant range for medical investigations are presented. Mn(III) tetratolylporphyrin chloride (MnTTPCl), spherical gold colloid (n-Au), and their hybrid (MnTTPCl/n-Au) were chosen to be comparatively investigated by ultraviolet–visible spectroscopy in the presence of AA. The hybrid material (MnTTPCl/n-Au) has the best capacity to detect concentrations of AA in the range of 2.6 × 10−6–4.38 × 10−5 M. Modified glassy carbon (GC) electrodes were obtained by thin film deposition of MnTTPCl, n-Au alone, and in successive mixed thin films, comparing their response during the electrochemical oxidation of AA. The electrocatalytic effect of the MnTTPCl on the AA oxidation is justified both by the increase in the peak current density and by the shift toward more negative potentials (0.024 V). The GC/MnTTPCl electrode has the best electrocatalytic effect for the AA oxidation and is promising for sensor applications.

Porphyrins are versatile multifunctional biomimetic molecules that are obtained by condensation of pyrrole with the desired aromatic aldehydes. The porphyrin structure can be synthetically modified by either introduction of various peripheral functional groups or metals in its core, allowing creation of various porphyrin derivatives that exhibit amazing optoelectronic properties. This feature makes porphyrins molecules extremely useful especially in hybrid combination with photonic, electronic and magnetic compounds. This review is focused on the more recently obtained porphyrin-polymeric materials and on their various analytical, industrial and medical applications. The study underlines the assembling capacity of these porphyrin-polymer hybrids to form supramolecular tunable architectures by means of the association of more building block units. Porphyrin-polymer nano- and micro-materials play a preeminent role in sensing applications involving chromophores in the formulation of organic solar cells - due to their capacity to generate photo induced charge separation centers - and as new materials with interesting catalytic properties. Besides these technical applications, the photobactericidal activity of these porphyrin–polymer materials was evaluated against Gram positive and Gram negative strains bacteria and they represent an alternative to antibiotics in order to overcome the growing bacterial multiresistance. Polymer functionalization with porphyrin is commonly used to overcome some drawbacks such as self-quenching and photo-toxicity to the skin produced by the bare porphyrins, when used as photosensitizers in the non-invasive Photodynamic therapy of cancer (PDT).

A novel hybrid mesoporous silica–Mn–porphyrin nanomaterial and its application for fluorescent detection of H2O2 is reported. The hybrid was obtained by sol–gel method in two steps acid-base catalysis and was completely characterized by UV–vis, FT-IR, fluorimetric, DRX, BET, AFM, TEM and conductivity investigations. The influence of adding H2O2 to the silica–Mn–porphyrin hybrid generates major differences regarding the optical, textural and morphological properties of the material. The dependence between H2O2 concentration and the fluorescence intensity, measured at the emission maximum at the wavelength 655 nm, is linear with an excellent correlation coefficient of 0.9945. The high sensitivity for hydrogen peroxide in wet media noticed for this hybrid, accompanied by changes in color, justifies further investigations towards design of fluorimetric and colorimetric O2 gas sensors. The low conductivity of the manganese(III)porphyrin–silica hybrid (0.694 × 10−8 S/cm) can be improved, so that this material may become a promising one for electrochemical cells (batteries).

Zn(Ta1-xNbx)2O6 pseudo-binary oxide nanocrystalline materials (where x = 1; 0.5; 0.1; 0.05 and 0) were obtained through the solid-state method and characterized by X-ray diffraction, Fourier Transform Infrared Spectroscopy and Ultraviolet-visible spectroscopy. In addition, their morphology and topography have been determined by field emission-scanning electron microscopy (SEM) and atomic force microscopy (AFM). There is a significant dependence between the rugosity and the uniformity of crystals. The evenly crystals organized in multilayers have the lowest value of rugosity and the non uniform fractal type architectures have the highest value of rugosity. The compounds? anti-corrosion features were evaluated after deposition on carbon steel (OL) in 0.1 M Na2SO4 media by open circuit potential measurement and potentiodynamic polarization technique with Tafel representation. The inhibition efficiency of pseudo-binary oxides deposited on carbon steel electrode was in the range 42.3-52.7 % promising for their further multiple layer deposition with porphyrins in order to improve anticorrosion properties. Due to the high band gap (3.80 - 4.30 eV) provided by increasing the tantalum content, four of these pseudo-binary oxides might find applications in photovoltaic cells.

Pt(II) 5,10,15,20-tetra(4-methoxy-phenyl)-porphyrin (PtTMeOPP) was used in the construction of new ion-selective sensors. The potentiometric response characteristics (slope and selectivity) of iodide and bromide-selective electrodes based on (PtTMeOPP) metalloporphyrin in o-nitrophenyloctylether (NPOE), dioctylphtalate (DOP) and dioctylsebacate (DOS) plasticized poly(vinyl chloride) membranes are compared. The best results were obtained for the membranes plasticized with DOP and NPOE. The sensors have linear responses with near-Nernstian slopes toward bromide and iodide ions and good selectivity. The membrane plasticized with NPOE was electrochemically characterized using the EIS method to determine its water absorption and the diffusion coefficient into the membrane.

Summary Polyaniline (PANI) based composites and multilayers as well as porphyrin derivatives have been previously reported as efficient anti-corrosion coatings. In our studies, 5,10,15,20-tetra(4-methylphenyl)-21H,23H-porphyrin (TMP) was adsorbed on carbon steel surface before PANI electrodeposition, in order to improve the corrosion protection of PANI films on steel. The corrosion behavior of the TMP-PANI bilayer carbon steel modified electrodes was investigated in 0.1 M H2SO4 solution using electrochemical tehniques. It was found that TMP-PANI coatings can provide a good protection against carbon steel corrosion. The corrosion rate for the composite coated steel was significantly lower than that of the bare steel, and exhibited an inhibition efficiency of ∼80%.

The present report deals with the tailoring, preparation and characterization of novel nanomaterials sensitive to CO2 for use in detection of this gas during space habitation missions. A new nanostructured material based on mixed substituted asymmetrical A3B porphyrin: 5-(4-pyridyl)-10,15,20-tris(3,4-dimethoxyphenyl)-porphyrin (PyTDMeOPP) was synthesized and characterized by 1H-NMR, FT-IR, UV-vis, fluorescence, MS, HPLC and AFM. Introducing one pyridyl substituent in the 5-meso-position of porphyrin macrocycle confers some degree of hydrophilicity, which may cause self-assembly properties and a better response to increased acidity. The influence of pH and nature of the solvent upon H and J aggregates of the porphyrin are discussed. Porphyrin aggregation at the air–THF interface gave a triangular type morphology, randomly distributed but uniformly oriented. When deposition was made by multiple drop-casting operations, a network of triangles of uniform size was created and a porous structure was obtained, being reorganized finally in rings. When the deposition was made from CHCl3, ring structures ranging in internal diameter from 300 nm to 1 µm, but with the same width of the corona circular of approx. 200 nm were obtained. This porphyrin-based material, capable of generating ring aggregates in both THF and CHCl3, has been proven to be sensitive to CO2 detection. The dependence between the intensity of porphyrin UV-vis absorption and the concentration of CO2 has a good correlation of 98.4%.

The successful preparation of a novel dimer complex formed between 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)-porphyrin Fe(III) chloride and (5,10,15,20-tetraphenylporphinato) dichlorophosphorus(V) chloride using the well-known reactivity of the P–X bond is reported. The obtained complex was characterized by UV-vis, Fourier transform infrared spectroscopy (FT-IR), fluorescence, 1H-NMR, 13C-NMR, and 31P-NMR spectroscopic techniques and also by additional Heteronuclear Single Quantum Coherence (HSQC) and Heteronuclear Multiple Bond Correlation (HMBC) experiments in order to correctly assign the NMR signals. Scanning electron microscopy (SEM) and EDX quantifications completed the characterizations. This novel porphyrin dimer complex demonstrated fluorescence sensing of H2O2 in water for low oxygen concentrations in the range of 40–90 µM proving medical relevance for early diagnosis of diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and even cancer because higher concentrations of H2O2 than 50 μM are consideredcytotoxic for life. Due to its optical properties, this novel metalloporphyrin–porphyrin based complex is expected to show PDT and bactericidal activity under visible-light irradiation.

The present report is concerned with the designing, obtaining and characterization of novel light -sensitive molecules, belong- ing to second generation meso-tetraarylporphyrin derivatives. A new structure of A3B porphyrin, namely: 5-(4-pyridyl)-10,15,20-tris(4- phenoxyphenyl)-porphyrin was synthesized in fair yield by multicomponent reaction and characterized by 1 H-NMR, FT-IR, UV-vis, fluo- rescence, MS, HPLC, TLC, AFM and XRD techniques. Tailoring porphyrins by introducing a pyridyl substituent in one of the meso-aryl groups confers some degree of hydrophilicity and may cause absorption and fluorescence emission bands in the long wavelength region. Besides, as it was expected, because of the relatively rigid planar structure, due to substitution with three phenoxy substituents, this por- phyrin is characterized by a value of 0.219 for fluorescence quantum yield, a higher value in comparison with usual porphyrins. In solu- tion, by UV-vis and fluorescence spectra, the effects of pH and concentration upon H and J aggregates of the porphyrin are discussed. X- ray diffraction and atomic force microscopy investigations proved that this newly synthesized porphyrin is able to generate stable self- assembly in preferred orientations, such as multilayer of lamellar triangles, densely packed and homogeneous, with dimensions around 440 nm, finally forming pyramidal type structures. CHCl3 favors the spiral organization of the pyramids so that rings and even tubes of various diameters ranging from 1μm to 4.5 μm were formed.

This study is concerning about optical and morphological properties of novel porphyrin doped silica materials consisting in 5,10,15,20-tetrakis(4-allyloxyphenyl)porphyrin (TAPP) encapsulated in silica matrices, exhibiting intensive absorption of light in the red-near IR region. The silica-porphyrin materials were prepared by the sol–gel process, by using different porphyrin immobilization schemes: in situ and by impregnation. As starting materials tetraethoxysilane and isobuthyltrietoxysilane, as silica precursors, N-buthyl-3-methylpyridinium tetrafluoroborate ionic liquid, as additive, and hydrochloric acid and sodium fluoride, as catalysts, were used. The obtained hybrid porphyrin-silica materials were characterized by using BET measurements (Brunauer–Emmett–Teller analysis), thermal analysis, FT-IR, fluorescence and UV–vis spectroscopy techniques. UV–vis behavior and fluorescence emissions and excitations were evaluated in terms of synthesis stages and immobilization processes. The obtained hybrid porphyrin-silica materials presented increased fluorescence emission with maxima situated at about 655 nm and 715 nm in comparison with the porphyrin base that make these transparent materials candidates for second generation photosensitizers. BET analysis revealed that every introduction of TAPP causes decreasing on surface area of the nanomaterial. Although, when the porphyrin is immobilized by in situ method the reduction is lower than in case of using impregnation method, that is leading to the conclusion that the porphyrin is placed inside on the silica network in both studied cases, independent of the performed method of immobilization. The pore size is narrowly distributed in the range of 1.97–3.81 nm for in situ obtained materials and in the range of 3.07–4.62 for hybrids obtained by impregnation. These materials with tunable pore sizes diameter are promising for building of sensor devices.

The present study is dealing with the obtaining of transparent hybrid silica materials encapsulating 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)-21H,23H-porphyrin designated for advanced optoelectronic devices. The porphyrin was synthesized by three methods: an Adler-type reaction between pyrrole and 3,4-dimethoxybenzaldehyde in propionic acid medium; by Lindsey condensation of pyrrole with 3,4-dimethoxybenzaldehyde in the presence of BF3·OEt2 and by a multicomponent reaction by simultaneously using of pyrrole and two different aldehydes: 3,4-dimethoxybenzaldehyde and 3-hydroxybenzaldehyde. The 3,4-dimethoxyphenyl substituted porphyrin was characterized by HPLC, TLC, UV–vis, FT-IR, 1H NMR and 13C NMR analysis. Excitation and emission spectra were also discussed in terms of pH conditions. The hybrid materials, consisting in the porphyrin encapsulated in silica matrices, have been prepared successfully via the two steps acid–base catalyzed hydrolysis and condensation of tetraethylorthosilicate using different approaches of the sol–gel process: in situ, by impregnation and by sonication. The synthetic conditions and the compositions were monitored and characterized by using spectroscopic methods such as FT-IR, fluorescence and UV–vis. Atomic force microscopy (AFM) has been applied to observe the columnar or pyramidal nanostructures which are formed by the immobilization of porphyrin on the silica matrices.

The new asymmetrical, phenyl substituted porphyrin structure, namely: 5,10,15-tris(3-hydroxy-phenyl)-20- (3,4-dimethoxy-phenyl)-21H,23H-porphyrin, along with the nanostructured glasses and silica-based nanoparticles embedded with this compound were synthetized and characterized as to be designated for potential use in construction of advanced optoelectronic devices or electrochemical sensors. This porphyrin was synthesized by a multicomponent Adler- Longo type reaction using two different substituted aldehydes, and next characterized by HPLC, TLC, MS, UV-vis, fluorescence spectroscopy, AFM, 1 H-NMR and 13 C-NMR analysis. The observed changes in UV-vis and emission spectra were also discussed in terms of various pH conditions. The series of novel porphyrin-silica nanomaterials have been prepared by using silica matrices obtained in two variable sol-gel processes, i.e. via the one step acid- or two steps acid- base-catalyzed hydrolysis and condensation of tetraethylorthosilicate. Especially, the hybrid monolithic glass nanomaterials obtained here via the one step acid-sol-gel procedure exhibited a high intensity of the emission spectra bands and, besides, a very sharp bathochromic shift in the red region towards 723 nm, thus making also these nanoparticles as the valuable source of potential second generation photosensitizers. In the atomic force microscopy (AFM) measurements this hybrid nanomaterials displayed the spherical and highly monodispersed particles of ultra low size (less than 70 nm and with an average height of 20 nm), controlled shape, high porosity, and superior stability as the potential water-insoluble photosensitizers.

The present work is concerned with the manganese complexes of 5,10,15,20-tetraphenylporphyrin and of 5,10,15,20-tetra(3-hydroxyphenyl)porphyrin, which were prepared by metallation of the corresponding porphyrin ligands, and the study of their spectroscopic and photophysical behavior under strongly acidic and alkaline conditions. The second objective was to obtain and study some new hybrid materials, with special optoelectronic and surface properties, by impregnation of silica gels obtained by one step acid and by two steps acid-base catalysis with these Mn-porphyrins. The resulting nanomaterials exhibited interesting bathochromic and hyperchromic effects of their second band in the emission spectra in comparison with the Mn-porphyrins and also they have distinct orientation of the aggregates on surfaces, as shown by AFM images, making them useful for applications in medicine, formulation of sensors and for environmental-friendly catalysts for photodegradation of organic compounds.

Hybrid porphyrin–silica materials consisting in 5,10,15,20-tetratolyl-21H,23H-porphine, encapsulated in silica matrices were obtained by sol–gel method. The hydrolysis and condensation reactions were performed by using tetraethylorthosilicate as precursor, either in one-step acid or in two steps acid–base catalysis, assisted or not by an ultrasonic field. The porphyrin–silica hybrid materials were monitored and characterized by AFM, FT-IR, fluorescence and UV–vis spectroscopy. As a result of porphyrin entrapping into silica gels, a general phenomenon regarding hyperchromic effects of the Q bands, occurs. UV–vis study revealed that during the sol–gel process, major changes regarding porphyrin ring structure occur, especially at acidic pH, when the dicationic species of porphyrin are formed. During acid–base catalyzed method the dye molecules tend to aggregate by π−π and hydrophobic co-facial interactions of sandwich H-type. In acid catalyzed process, the protonation of the porphyrins prevent the formation of aggregates, due to increased electrostatic repulsion between the molecules.

Porphyrins play a major role as active photosensitizers in noninvasive optical photodynamic therapy (PDT). In a modular approach, this paper presents a short review of the recent developments of porphyrin structures and materials with improved photosensitizing properties and then presents the synthesis and characterization of a series of new second generation asymmetrical meso-tetraphenylporphyrins varied by substituent in the meta positions of the phenyl rings with either -OH or -OCH3 groups, whereas in the para positions only with -OCH3 groups. The new series of differentially functionalized porphyrins were obtained by a combinatorial multicomponent synthesis (Adler-Longo method) by simultaneously using two different aldehydes: 3,4-dimethoxybenzaldehyde and 3-hydroxybenzaldehyde. The porphyrins were isolated, purified and characterized by HPLC, TLC, UV-vis, fluorescence, MS, 1H-NMR, and 13C-NMR analysis, accompanied by DEPT 135 experiments. Because of the fact that the medium in cancerous tissues is often more acidic than in normal tissues, the capacity of these porphyrins to exist simultaneously in aggregated and protonated forms was also investigated, in tetrahydrofuran (THF) and acid THF-water systems, underlying the changes in the photophysical behaviour. The relative fluorescence quantum yields (Phif) were calculated in comparison with meso-tetraphenylporphyrin (TPP), and the values between 0.14-0.26 were found to be promising for further trials. The series of asymmetrically substituted tetraphenylporphyrins, as the new class of supramolecular materials, are suitable for further functionalization in order to improve their photophysical properties, and they could represent interesting potential PDT photosensitizers.

Dichloro-p-tolylphosphine, involved in a Mannich type reaction, together with o-aminophenol or 1,2- diaminopropane and acetone generated two phosphorin- 2-oxide ring compounds, namely: hexahydro-3,3,5-trimethyl-2-p-tolyl-1,4,2-diazaphosphorine- 2-oxide and 3,4-dihydro-3,3-dimethyl-2-p-tolyl-2H-1,4,2-benzoxaza- phosphorine-2-oxide. The two compounds were fully characterized by MS, IR, UV, 1H-NMR, and gas chromatography. Anothermain objective of the present study was to examine to what extent the treatments with different concentrations of the above-mentioned diaza- and benzoxaza-compounds affected the content of leaf chlorophyll of a monocotyledonous plant (wheat), in correlation with all the other changes concerning the general development of the tested plants. .

This article presents the synthesis and characterization of a new phosphorus heterocycle, namely 2-n-propyl-3-ethyl-3-methyl-1,4,2-benzoxaza-phosphorine-2-oxide, by a Mannich-type reaction between n-propyl-dichlorophosphine, methyl ethyl ketone, and o-aminophenol. Taking into consideration that chlorophyll contents in plants were revealed to have connection with nitrogen and phosphorus concentrations at early growth stage, and because the above-mentioned heterocyclic compound can be considered as a phosphonic analogous of naturally occuring α-aminoacids, it was expected to develop biological activity from it. That is the reason why 2-n-propyl-3-ethyl-3-methyl-1,4,2-benzoxaza-phosphorine-2-oxide was subjected for biological tests on wheat. The present study was also undertaken to investigate the interrelationship between chlorophyll content, dry matter, and other growth parameters of wheat, after treatment with different concentrations of 2-n-propyl-3-ethyl-3-methyl-1,4,2-benzoxaza-phosphorine-2-oxide.

Background Copper is an essential trace element with a great importance in industry, environment and biological systems. The great advantage of ion-selective sensors in comparison with other proposed techniques is that they are measuring the free metal ion activity which is responsible for their toxicity. Porphyrins are known to be among the best ionophores in formulation of ion-selective sensors. Results A symmetrically substituted meso-porphyrin, namely: 5,10,15,20-tetrakis(4-allyloxyphenyl)porphyrin (TAPP) was used in the construction of a new copper selective-sensor and was also tested for the removal of copper from waste waters. The potentiometric response characteristics (slope and selectivity) of copper-selective electrodes based on TAPP in o-nitrophenyloctylether (o-NPOE), dioctyl phtalate (DOP) and dioctyl sebacate (DOS) plasticized with poly(vinyl chloride) membranes are compared. Conclusions The best results were obtained for the membrane plasticized with DOP. The sensor has linear response in the range 1x10-7 – 1x10-1 M with 28.4 ± 0.4 mV/decade near-Nernstian slope towards copper ions and presents good selectivity. Due to its chelating nature, the same porphyrin was also tested for the retention of copper from synthetic copper samples, showing a maximum adsorption capacity of 280 mg/g.

This paper is directed towards the development of safe, and thermally stable solid polymer electrolytes. Linear phosphorus-containing (co)polyesters are described, including their synthesis, thermal analysis, conductivity, and non-flammability. Polycondensation of phenylphosphonic dichloride (PPD) with poly(ethylene glycol) (PEG 12000) with and without bisphenol A (BA) was carried out using solid-liquid phase transfer catalysis. Potassium phosphate is used as base. Yields in the range of 85.0–88.0%, and inherent viscosities in the range of 0.32–0.58 dL/g were obtained. The polymers were characterized by gel permeation chromatography, FT-IR, 1H- and 31P-NMR spectroscopy and thermal analysis. Their flammability was investigated by measuring limiting oxygen index values. The polymers are flame retardants and begin to lose weight in the 190 °C–231 °C range. Solid phosphorus- containing (co)polyesters were complexed with lithium triflate and the resulting ionic conductivity was determined. Conductivities in the range of 10−7–10−8 S cm−1 were obtained.

The purpose of our present work was to study some chemical properties of p-tolyldichlorophosphine and di(p-tolyl)chlorophosphine involved in reactions with organo-lithium compounds, with 1,2-diols and also when are reactants in variants of Reformatsky and Mannich reactions, in order to obtain some new substances of trivalent and pentavalent phosphorus useful for our further investigations. All the new phosphorus(III) and (V) compounds were obtained in fair yields, and were characterized by elemental analysis, IR, and NMR spectroscopy. They will find potential synthetic utility as convenient ligands for transition metals and reagents for the preparation of phosphonium salts, for obtaining chiral substances and as biologically active ring substances.

A novel fluorescent pH sensor based on 5-(4-carboxy-phenyl)-10,15,20-tris(phenyl)-porphyrin, as sensing agent, has been developed. The carboxyl functionalized asymmetric porphyrin has been synthesized and characterized by high performance liquid chromatography (HPLC), thin layer chromatography (TLC), proton nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible (UV–vis), emission, excitation and mass spectrometry (MS) spectra. Optical and fluorescence behaviors were investigated in relationship with variation of acid concentration in the range of acid pH from 1.5 to 5.5. Upon increasing the acidity of the solution, the decrease of the fluorescence intensity was noticed, as a linear function of pH. Different metal ions were tested to put into evidence the changes regarding the fluorescence intensity, but the fluorescence obtained results revealed no significant interference on pH determination. The conclusion is that the proposed fluorescent sensor can measure pH in acid range in the presence of different metal ions making this sensor a proper one for pH determinations in leaching solutions of the recyclable processes of valuable metals. Keywords: Functionalized porphyrin, Fluorescence, pH Sensor, Acid media, UV–vis