Multifunctional hybrid materials with applications in gas sensing or dye removal from wastewaters were obtained by incorporation into silica matrices of either Pt(II)-5,10,15,20-tetra-(4-allyloxy-phenyl)-porphyrin (PtTAOPP) or platinum nanoparticles (PtNPs) alone or accompanied by 5,10,15,20-tetra-(4-allyloxy-phenyl)-porphyrin (TAOPP). The tetraethylorthosilicate (TEOS)-based silica matrices were obtained by using the sol-gel method performed in two step acid-base catalysis. Optical, structural and morphological properties of the hybrid materials were determined and compared by UV-vis, fluorescence and FT-IR spectroscopy techniques, by atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM) and by Brunauer–Emmett–Teller (BET) analysis. PtTAOPP-silica hybrid was the most efficient material both for CO2 adsorption (0.025 mol/g) and for methylene blue adsorption (7.26 mg/g) from wastewaters. These results were expected due to both the ink-bottle mesopores having large necks that exist in this hybrid material and to the presence of the porphyrin moiety that facilitates chemical interactions with either CO2 gas or the dye molecule. Kinetic studies concerning the mechanism of dye adsorption demonstrated a second order kinetic model, thus it might be attributed to both physical and chemical processes.

The development of UV–vis spectrophotometric methods based on metalloporphyrins for fast, highly sensitive and selective anion detection, which avoids several of the practical challenges associated with other detection methods, is of tremendous importance in analytical chemistry. In this study, we focused on achieving a selective optical sensor for triiodide ion detection in traces based on a novel hybrid material comprised of Pt(II) 5,10,15,20-tetra(4-methoxy-phenyl)-porphyrin (PtTMeOPP) and gold nanoparticles (AuNPs). This sensor has high relevance in medical physiological tests. The structure of PtTMeOPP was investigated by single crystal X-ray diffraction in order to understand the metal surroundings and the molecule conformation and to assess if it qualifies as a potential sensitive material. It was proven that the Pt-porphyrin generated 1D H-bond supramolecular chains due to the weak C-H···O intermolecular hydrogen bonding. The presence of ordered voids in the crystal encouraged us to use PtTMeOPP as the sensing material for triiodide ion and to enhance its potential in a novel AuNPs/PtTMeOPP hybrid by the synergistic effects provided by the plasmonic gold nanoparticles. The spectrophotometric sensor is characterized by a detection limit of 1.5 × 10−9 M triiodide ion concentration and a remarkable confidence coefficient of 99.98%.

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 (1.05–3.9 × 10−7 M) and by electrochemical method, in a larger concentration range from 1 × 10−6 M to 5 × 10−5 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.

Hybrid nanomaterials consisting in 5,10,15,20-tetrakis(4-amino-phenyl)-porphyrin (TAmPP) and copper nanoparticles (CuNPs), platinum nanoparticles (PtNPs), or both types (Pt@CuNPs) were obtained and tested for their capacity to optically detect uric acid from solutions. The introduction of diverse metal nanoparticles into the hybrid material proved their capacity to improve the detection range. The detection was monitored by using UV-Vis spectrophotometry, and differences between morphology of the materials were performed using atomic force microscopy (AFM). The hybrid material formed between porphyrin and PtNPs hasthe best and most stable response for uric acid detection in the range of 6.1958 × 10−6–1.5763 × 10−5 M, even in the presence of very high concentrations of the interference species present in human environment.

The increasing resistance against classical antibiotic treatment forces the researchers to develop novel non-toxic antimicrobial agents. The aim of this study was to determine the antimicrobial properties of seven different porphyrins having distinctive hydrophobicity/hydrophilicity: P1 meso-tetra(4-methoxy-phenyl)porphyrin, P2 Zn(II)-meso-5,10,15,20-tetrapyridylporphyrin, P3 meso-tetra(p-tolyl)porphyrin, P4 5,10,15,20-tetraphenylporphyrin; P5 (5,10,15,20-tetraphenylporphinato) dichlorophosphorus(V) chloride, P6 5,10,15,20-tetrakis-(N-methyl-4-pyridyl) porphyrin-Zn(II) tetrachloride, P7 Zn(II)-5,10,15,20-meso-tetrakis-(4-aminophenyl)porphyrin. The meso-porphyrin derivatives were screened for their antimicrobial activity against six reference strains: Streptococcus pyogenes ATCC 19615, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 700603, Pseudomonas aeruginosa ATCC27853 and Candida albicans ATCC 10231. The antimicrobial activity of these samples was evaluated by the agar disk diffusion method and dilution method, with the determination of the minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC) and the minimum fungicidal concentration (MFC). The most significant result is provided by the water-soluble P5 manifesting an obvious antimicrobial activity against Streptococcus pyogenes. On the other hand, P6 is a moderately active derivative against Streptococcus pyogenes and Escherichia coli and P7 presents moderate activity against Streptococcus pyogenes and Staphylococcus aureus. All the tested porphyrin bases, presenting hydrophobic character, have no antimicrobial activity under the investigated conditions. The common characteristics of the porphyrins that act as promising antimicrobial agents in the non-irradiated methods are: the cationic nature, the increased hydrophilicity and the presence of both amino functional groups grafted on the porphyrin ring and the coordination with Zn or phosphorus in the inner core.