Oxygen-sensing properties of 5,10,15,20-tetraphenylporphinato platinum(II) and palladium(II) covalently bound on poly(isobutyl-co-2,2,2-trifluoroethyl methacrylate)

Polymer matrix: A good substrate material for oxygen probes used in pressure sensitive paints

Over the past few years, surface pressure measurement has fundamental importance in many areas, particularly, aerodynamic research. Conventional methods involve pressure taps, but due to the nature of these pressure taps, only pressure information of isolated points on model surface is available, which limit their applications in aerodynamics studies. Recently the newly developed approach, pressure sensitive paint (PSP) has revolutionized such pressure measurements and various PSP materials have been developed for aerodynamics research. Hence, the main focus of this review is to study the interactions of polymers with different oxygen probes and polymeric role as supporting material in the maturation of PSP. In this review, the selected PSP materials are categorically elucidated in terms of their advantages and limitations to give a fair insight about their applicability. Further, we have summarized and articulated such particular optical oxygen sensing materials either that have been used as PSP or have potential to be used as PSP materials.

Preparation and dielectric properties of poly(acrylonitrile-co-2,2,2-trifluoroethyl methacrylate) materials via radical emulsion copolymerization

Radical emulsion copolymerization of acrylonitrile (AN) with 2,2,2-trifluoroethyl methacrylate (MATRIF) and their homopolymerization initiated by potassium persulfate (KPS) were studied.

Electrospun nanofibers and spin coated films prepared from side-chain copolymers with chemically bounded platinum (II) porphyrin moieties for oxygen sensing and pressure sensitive paints

Pressure sensitive paints (PSP) containing oxygen probes were primarily used to measure air pressure. In this perspective, a polymerizable methacrylate-derived tetraphenylporphinato platinum(II) (PtTPP-MA) monomer was copolymerized with acrylic/vinyl monomers to produce four different copolymers. Octafluoropentyl methacrylate (OCFPM) and pentafluorophenyl acrylate (PFPA) were used as fluorinated monomers. Methyl methacrylate (MMA) and styrene (S) were used as non-fluorinated monomers. The structures and physical properties of the polymers were confirmed by ¹H NMR, ¹⁹F NMR, GPC, and DSC. Experimental conditions were optimized to get fine nanofibers. Pressure sensing electrospun membranes and spin coated films were fabricated. Nanofibers showed fast response and good sensitivity towards gaseous oxygen. The influence of types of substrate and polymer natures on response time, oxygen sensitivity, and pressure responses were deliberated. Among our synthesized copolymers, poly(PS-co-PFPA-co-OCFPM-co-PtTPPMA) (Polymer P3) showed fast response time and good pressure sensitivity both as spin coated films and nanofibers.

Porphyrinoids for Chemical Sensor Applications

Porphyrins and related macrocycles have been intensively exploited as sensing materials in chemical sensors, since in these devices they mimic most of their biological functions, such as reversible binding, catalytic activation, and optical changes. Such a magnificent bouquet of properties allows applying porphyrin derivatives to different transducers, ranging from nanogravimetric to optical devices, also enabling the realization of multifunctional chemical sensors, in which multiple transduction mechanisms are applied to the same sensing layer. Potential applications are further expanded through sensor arrays, where cross-selective sensing layers can be applied for the analysis of complex chemical matrices. The possibility of finely tuning the macrocycle properties by synthetic modification of the different components of the porphyrin ring, such as peripheral substituents, molecular skeleton, coordinated metal, allows creating a vast library of porphyrinoid-based sensing layers. From among these, one can select optimal arrays for a particular application. This feature is particularly suitable for sensor array applications, where cross-selective receptors are required. This Review briefly describes chemical sensor principles. The main part of the Review is divided into two sections, describing the porphyrin-based devices devoted to the detection of gaseous or liquid samples, according to the corresponding transduction mechanism. Although most devices are based on porphyrin derivatives, seminal examples of the application of corroles or other porphyrin analogues are evidenced in dedicated sections.

Conjugatable water-soluble Pt(II) and Pd(II) porphyrin complexes: novel nano- and molecular probes for optical oxygen tension measurement in tissue engineering

Measurement of oxygen tension in compressed collagen sheets was performed using matrix-embedded optical oxygen sensors based on platinum(II) and palladium(II) porphyrins supported on polyacrylamide nanoparticles. Bespoke, fully water-soluble, mono-functionalised Pt(II) and Pd(II) porphyrin complexes designed for conjugation under mild conditions were obtained using microwave-assisted metallation. The new sensors display a linear response (1/τ vs. O2) to varying oxygen tension over a biologically relevant range (7.0 × 10(-4) to 2.7 × 10(-1) mM) in aqueous solutions; a behaviour that is maintained following conjugation to polyacrylamide nanoparticles, and following embedding of the nanosensors in compressed collagen sheets, paving the way to innovative approaches for real-time resolution of oxygen gradients throughout 3D matrices useful for tissue regeneration.

Two-photon oxygen sensing with quantum dot-porphyrin conjugates

Supramolecular assemblies of a quantum dot (QD) associated to palladium(II) porphyrins have been developed to detect oxygen (pO2) in organic solvents. Palladium porphyrins are sensitive in the 0-160 Torr range, making them ideal phosphors for in vivo biological oxygen quantification. Porphyrins with meso pyridyl substituents bind to the surface of the QD to produce self-assembled nanosensors. Appreciable overlap between QD emission and porphyrin absorption features results in efficient Förster resonance energy transfer (FRET) for signal transduction in these sensors. The QD serves as a photon antenna, enhancing porphyrin emission under both one- and two-photon excitation, demonstrating that QD-palladium porphyrin conjugates may be used for oxygen sensing over physiological oxygen ranges.

Distributed fiber optical sensing of oxygen with optical time domain reflectometry

In many biological and environmental applications spatially resolved sensing of molecular oxygen is desirable. A powerful tool for distributed measurements is optical time domain reflectometry (OTDR) which is often used in the field of telecommunications. We combine this technique with a novel optical oxygen sensor dye, triangular-[4] phenylene (TP), immobilized in a polymer matrix. The TP luminescence decay time is 86 ns. The short decay time of the sensor dye is suitable to achieve a spatial resolution of some meters. In this paper we present the development and characterization of a reflectometer in the UV range of the electromagnetic spectrum as well as optical oxygen sensing with different fiber arrangements.

Application of metalloporphyrins as new catalysts for the efficient, mild and regioselective synthesis of quinoxaline derivatives

A simple, highly efficient and green procedure for the condensation of aryl and alkyl 1,2-diamines with α-diketones in the presence of catalytic amounts of metalloporphyrins at room temperature is described. Using this method, quinoxaline derivatives as biologically interesting compounds are produced in high to excellent yields and short reaction times. In this report, the effects of central metal in porphyrin core and substituents on tetraphenylporphyrin skeleton have been studied.

Determination of oxygen permeabilities in thin polymer films using quenching of upconverted fluorescence in porphyrins

Proof-of-principle is demonstrated for a method of measuring the oxygen diffusion properties of thin polymer films based on quenching of the delayed upconverted S2 fluorescence of Zn(II) meso-tetraphenylporphine (ZnTPP). Empirical oxygen diffusion coefficients and permeability coefficients for poly(vinyl alcohol) (PVA) have been computed using Stern–Volmer kinetics in the steady-state regime and a nonlinear gas solubility model in the time domain. Simplified dual-mode theory has been used to calculate crude theoretical oxygen permeability coefficients to compare with the experimental values. It is confirmed that oxygen permeability in the PVA matrix is controlled largely by the characteristics of the polymer matrix, particularly its water content and distribution.