Tetraphenylporphyrin Chloride Research Articles

Evidence of carbon-supported porphyrins pyrolyzed for the oxygen reduction reaction keeping integrity

Fe(III) 5,10,15,20-(tetraphenyl)porphyrin chloride (FeTPP) and Co(III) 5,10,15,20-(tetraphenyl)porphyrin chloride (CoTPP) were adsorbed on carbon Vulcan and studied as electrocatalysts for the oxygen reduction reaction (ORR) before and after pyrolysis. The pyrolysis process was also simulated through ab initio molecular dynamic simulations and the minimum energy path for the O2 dissociation after the interaction with the metal center of the FeTPP and CoTPP were calculated. After the pyrolysis the FeTPP showed the best performances reducing O2 completely to H2O with increased limiting current and lower overpotential. Tafel slops for the various catalysts did not change after the pyrolytic process suggesting that the mechanism for the ORR is not affected by the heat treatment. TEM images, X-ray diffraction, XPS spectroscopy, 57Fe Mössbauer, and DFT simulations, suggest that there is no breakdown of the macrocyclic complex at elevated temperatures, and that the macro cyclic geometry is preserved. Small variations in the Metal-O2 (M-O2) binding energies and the M–N bond length were observed which is attributed to the dispersive interaction between the macrocycles and the irregular surface of the Vulcan substrate induced by the heat treatment and causing better interaction with the O2 molecule. The theoretical strategy herein applied well simulate and explain the nature of the M–N–C active sites and the performances towards the ORR.

Stability of Fe(III) and Sn(IV) Metalloporphyrins Adsorbed on Cation-Exchanged Montmorillonite

The iron(III)tetraphenylporphyrin chloride Fe(III)TPPCl, iron(III)tetra-naphthylporphyrin Fe(III)TNPCl, μ-oxo-bis[tetraphenylporphyriniron(III)] [(Fe(III)TPP)2O], μ-oxo-bis[tetranaphthylporphyriniron(III)] [(Fe(III)TNP)2O], tin(IV)tetraphenylporphyrin chloride Sn(IV)TPPCl2 and tin(IV)tetra-naphthylporphyrin Sn(IV)TNPCl2 complexes were all found to be adsorbed onto the montmorillonite MMT clay without demetallation. The evidence from the visible absorption and diffuse reflectance spectra all showed that the species present on the montmorillonite are the metallated form. Also the evidence from Mossbauer spectroscopy confirm these findings. The only process that occurs is that the dimeric form of the iron complexes underwent transformation to the monomeric form. The clay-complex systems were characterized using visible absorption spectra, diffuse reflectance spectra, X-ray diffraction, Mossbauer spectra and Electron microscopy.
 HIGHLIGHTS
 
 Fe(III)TPPCl, Fe(III)TNPCl, Sn(IV)TPPCl2, and Sn(IV)TNPCl2 porphyrin complexes adsorbed onto the montmorillonite clay without demetallation
 The dimeric forms of iron porphyrin complexes [(Fe(III)TPP)2O] and [(Fe(III)TNP)2O are converted to the monomeric form when adsorbed on montmorillonite clay
 The weak acidity of montmorillonite clay does not have the ability to cause demetallation of the metallo complexes of porphyrin

Interfacial electronic properties of FeTPP-Cl on HOPG

Conjugated tetrapyrrole complexes have potential for novel spintronic and optoelectronic devices. Detailed understanding of electronic properties at molecule–substrate interface is essential for their potential applications. In this report, electronic properties of iron (III) chloride tetraphenylporphyrin (FeTPP-Cl, C44H28ClFeN4) thin films on highly oriented pyrolytic graphite (HOPG) have been investigated using photoemission and X-ray absorption spectroscopy. Photoemission analysis shows that no significant charge transfer takes between FeTPP-Cl and HOPG. Fe 2P3/2 core level analysis indicates towards dechlorination of FeTPP-Cl on HOPG in the monolayer regime. Fe L2,3 edge X-ray absorption spectroscopy reveal that iron oxidation state changes from +2 to +3 due to adsorption on to HOPG, suggesting a substrate driven dechlorination of FeTPP-Cl. Curve fitting analysis of XPS Fe 2p3/2 spectrum for the deposition of FeTPP-Cl on HOPG in the monolayer regime confirms +2 oxidation state of central metal atom. An interface dipole of 0.2 eV has been found at FeTPP-Cl/HOPG interface suggesting weaker molecule–substrate interactions.

Quick and Easy Method to Dramatically Improve the Electrochemical CO2 Reduction Activity of an Iron Porphyrin Complex

AbstractThe development of artificial molecular catalysts for CO2 reduction is the key to solving energy and environmental problems. Although chemical modifications can generally improve the catalytic activity of this class of compounds, they often require complicated synthetic procedures. Here, we report a simple procedure that dramatically enhances electrochemical CO2 reduction activity. A one‐step counteranion‐exchange reaction increased the solubility of a commercially available catalyst, iron(III) tetraphenylporphyrin chloride, in a variety of solvents, allowing the investigation of its catalytic performance under various conditions. Surprisingly, the turnover frequency for CO evolution in acetonitrile (MeCN) reached 7 300 000 s−1, which is the highest among those of current best‐in‐class molecular catalysts. This excellent catalytic activity originates from the unique reaction between the generated FeI species and CO2 in MeCN during catalysis. The present study offers a “quick and easy” method for obtaining an efficient catalytic system for electrochemical CO2 reduction.

Quick and Easy Method to Dramatically Improve the Electrochemical CO2 Reduction Activity of an Iron Porphyrin Complex.

The development of artificial molecular catalysts for CO2 reduction is the key to solving energy and environmental problems. Although chemical modifications can generally improve the catalytic activity of this class of compounds, they often require complicated synthetic procedures. Here, we report a simple procedure that dramatically enhances electrochemical CO2 reduction activity. A one-step counteranion-exchange reaction increased the solubility of a commercially available catalyst, iron(III) tetraphenylporphyrin chloride, in a variety of solvents, allowing the investigation of its catalytic performance under various conditions. Surprisingly, the turnover frequency for CO evolution in acetonitrile (MeCN) reached 7 300 000 s-1 , which is the highest among those of current best-in-class molecular catalysts. This excellent catalytic activity originates from the unique reaction between the generated FeI species and CO2 in MeCN during catalysis. The present study offers a "quick and easy" method for obtaining an efficient catalytic system for electrochemical CO2 reduction.

Vanadium- and Chromium-Catalyzed Dehydrogenative Synthesis of Imines from Alcohols and Amines

Vanadium(IV) tetraphenylporphyrin dichloride and chromium(III) tetraphenylporphyrin chloride have been developed as catalysts for the acceptorless dehydrogenation of alcohols. The catalysts have be...

Stretchable memory loops and photovoltaic characteristics of organic-inorganic solid-state iron (III) chloride tetraphenyl porphyrin /p-Si(111) nanostructure devices

Iron (III) chloride tetraphenyl porphyrin (FeTPPCl) nanostructure decorated films were grown by thermal evaporation Technique (Edward-306) on p-type Silicon (111)/Al. The picked-up micrographs from the scan electron microscopy (SEM) declared that; the annealed FeTPPCl thin films at 350 ᵒC have a nanostructured decorated surface. An impedance spectrum of the Ag/FeTPPCl/p-Si/Al device is analyzed according to the Series Layer Model (SLM) as LRse[R1C1][R2C2] electrical equivalent circuit. The (Re(Z)-(-Im(Z))) complex-plane of Ag/FeTPPCl/p-Si/Al device is characterized by two composed semicircles with series resistance and induction behavior at higher frequencies. These results may be useful in Organic/Inorganic non-volatile memory scalable devices dependant on the electro‐resistive behavior. There are anomalies recorded types of cyclic (I–V) characteristic curves for the manufactured devices at different backward biasing voltages (under dark condition and illumination at room temperature). The power conversion efficiency (PCE) is 5.73 % at the power of the incident light intensity (Pin = 80 mW/cm2), whereas the projected area of the top electrode ∼ 73.6 × 10−3 cm2. The ideality parameter was larger than unity and the estimated barrier height is 0.46 eV. The series Rs and shunt Rsh resistances are characterized under different backward biasing voltage Vrev = {-2, -3, -4, -6−8, and -10 V} and a constant forward biasing voltage 5 V. When the backward voltage was stretched toward lower voltages (-4, -6, -8 and -10 V), Rsh is decreased as following: Rsh = 4.62, 4.73, 4.78, and 4.87 kΩ, respectively. The maximum values of the change in current (ΔIm) and resistance (ΔRm) are estimated and modulated, mathematically, corresponding to its backward biasing voltages. These results may be supporting utilizing this device in current and resistance electrical switching dependent backward biasing voltage application.

Properties and degradation of manganese(III) porphyrin thin films formed by high vacuum sublimation

Manganese porphyrins are of interest due to the optical, electronic and magnetic properties of the central metal ion, coupled to the low bandgap of the polyaromatic ring. These attractive characteristics are harnessed in solutions or in ultra-thin films, such as, for example, self-assembled monolayers. However, for devices, thicker films deposited using a controlled and reproducible method are required. Here we present the morphological, structural, chemical and optical properties of manganese(III) tetraphenylporphyrin chloride (MnTPPCl) thin films deposited using organic molecular beam deposition, typically employed to process analogue molecules for applications such as organic photovoltaics. We find, using a combination of UV-vis and X-ray photoelectron spectroscopies, that the sublimation process leads to the scission of the Mn–Cl bond. The resultant film is a Mn(II)TPP:Mn(III)TPPCl blend where approximately half the molecules have been reduced. Following growth, exposure to air oxidizes the Mn(II)TPP molecule. Through quantitative analysis of the time-dependent optical properties, the oxygen diffusion coefficient (D) [Formula: see text] is obtained, corresponding to a slow bulk oxidation following fast oxidation of a 8-nm-thick surface layer. The bulk diffusion D is lower than for analogous polycrystalline films, suggestion that grain boundaries, rather than molecular packing, are the rate-limiting steps in oxidation of molecular films. Our results highlight that the stability of the axial ligands should be considered when depositing metal porphyrins from the vapor phase, and offer a solvent-free route to obtain reproducible and smooth thin films of complex materials for engineering film functionalities.

Composites based on polylactide and manganese (III) tetraphenylporphyrin. Influence of concentration on the structure and properties

The bactericidal action of porphyrin has a very promising potential for medical applications. Therefore, composite materials based on L-Polylactide and manganese (III) chloride tetraphenylporphyrin were prepared. The aim of this work was to study the effects of the concentration of tetraphenylporphyrin on the structural features and mechanical properties of these composites. The concentration of the filler in the composites was in the range of 0.1–2 wt%. The sizes of the tetraphenylporphyrin microinclusions (15–40 μm) were determined using optical microscopy. It was found that the phase transition temperatures of polylactide in the presence of tetraphenylporphyrin varied by 1–2 °C, and the crystallinity degree increased by 4–5% in the composites compared with the pure polylactide. Using the method of electron paramagnetic resonance at 70 °C, an increase in the segmental mobility of the polymer matrix was detected as the tetraphenylporphyrin concentration in the composites was increased. The addition of manganese (III) chloride tetraphenylporphyrin complex microinclusions in the composites slightly enhanced the tensile strength and elongation at break of the polylactide matrix. Thus, the effects of the porphyrin manganese complex on the polylactide matrix and the properties of the composites were shown.

High-effective reactive oxygen species inducer based on Mn-tetraphenylporphyrin loaded PLGA nanoparticles in binary catalyst therapy

The mechanisms of binary catalyst therapy (BCT) and photodynamic therapy (PDT) are based on the formation of reactive oxygen species (ROS). This ROS formation results from specific chemical reactions. In BCT, light exposure does not necessarily initiate ROS formation and BCT application is not limited to regions of tissues that are accessible to illumination like photodynamic therapy (PDT). The principle of BCT is electron transition, resulting in the interaction of a transition metal complex (catalyst) and substrate molecule. MnIII- tetraphenylporphyrin chloride (MnClTPP) in combination with an ascorbic acid (AA) has been proposed as an appropriate candidate for cancer treatment regarding the active agents in BCT. The goal of this study was to determine whether MnClTPP in combination with AA would be a promising agent for BCT. The problem of used MnClTPP's, low solubility in water, was solved by MnClTPP loading into PLGA matrix. H2O2 produced during AA decomposition oxidized MnClTPP to high-reactive oxo-MnV species. MnClTPP in presence AA leads to the production of excessive ROS levels in vitro. ROS are mainly substrates of catalase and superoxide dismutase (H2O2 and O2●-). SOD1 and catalase were identified as the key players of the MnClTPP ROS-induced cell defense system. The cytotoxicity of MnClTPP-loaded nanoparticles (NPs) was greatly increased in the presence of specific catalase inhibitor (3-amino-1,2,4-triazole (3AT)) and superoxide dismutase 1 (SOD1) inhibitor (diethyldithiocarbamate (DDC)). Cell death resulted from the combined activation of caspase-dependent (caspase 3/9 system) and independent pathways, namely the AIF translocation to nuclei. Preliminary acute toxicity and in vivo anticancer studies have been revealed the safe and potent anticancer effect of PLGA-entrapped MnClTPP in combination with AA. The findings indicate that MnClTPP-loaded PLGA NPs are promising agents for BCT.

(Invited) What Did the Metals Know, and When Did They Know It? Femtosecond M-Edge XANES Reveals Short-Lived States in Transition Metal Catalysts

X-ray absorption near edge spectroscopy (XANES or NEXAFS) is a powerful technique for electronic structure determination. However, widespread use of femtosecond XANES is limited by the need for scare free-electron laser beamtime. We have developed M2,3-edge XANES, corresponding to 3p→3d transitions, as a reliable technique for measuring the electronic structure of first-row transition metal coordination complexes. The tabletop high-harmonic source provides femtosecond time resolution and 24/7 acessiblility. This talk present the photophysics of three transition metal complexes relevant to photocatalysis: Iron(III) tetraphenyl porphyrin chloride, which relaxes through a ligand-to-metal charge transfer state; Nickel (II) octaethylporphyrin, which relaxes through a 3(d,d) state; and a Co4O4 cubane that catalyzes water oxidation through one of two proposed pathways. We demonstrate M-edge XANES as a powerful new tool for identification of catalytic intermediates.

Single-Walled Carbon Nanotubes (SWCNTs) as Solid-Contact in All-Solid-State Perchlorate ISEs: Applications to Fireworks and Propellants Analysis

Herein, we present reliable, robust, stable, and cost-effective solid-contact ion-selective electrodes (ISEs) for perchlorate determination. Single-walled carbon nanotubes (SWCNTs) were used as solid-contact material and indium (III) 5, 10, 15, 20-(tetraphenyl) porphyrin chloride (InIII-porph) as an ion carrier. The sensor exhibited an improved sensitivity towards ClO4− ions with anionic slope of −56.0 ± 1.1 (R2 = 0.9998) mV/decade over a linear range 1.07 × 10−6 – 1.0 × 10−2 M and detection limit of 1.8 × 10−7 M. The short-term potential stability and the double-layer capacitance were measured by chronopotentiometric and electrochemical impedance spectroscopy (EIS) measurements, respectively. The sensor is used for ClO4− determination in fireworks and propellant powders. The results fairly agree with data obtained by ion chromatography.

Tabletop Femtosecond M-edge X-ray Absorption Near-Edge Structure of FeTPPCl: Metalloporphyrin Photophysics from the Perspective of the Metal.

Iron porphyrins are the active sites of many natural and artificial catalysts, and their photoinduced dynamics have been described as either relaxation into a vibrationally hot ground state or as a cascade through metal-centered states. In this work, we directly probe the metal center of iron(III) tetraphenyl porphyrin chloride (FeTPPCl) using femtosecond M2,3-edge X-ray absorption near-edge structure (XANES) spectroscopy. Photoexcitation at 400 nm produces a (π,π*) state that evolves in 70 fs to an iron(II) ligand-to-metal charge transfer (LMCT) state. The LMCT state relaxes to a vibrationally hot ground state in 1.13 ps, without involvement of (d,d) intermediates. The tabletop extreme-ultraviolet probe, combined with semiempirical ligand field multiplet calculations, clearly distinguishes between metal-centered and ligand-centered excited states and resolves competing accounts of Fe(III) porphyrin relaxation. This work introduces tabletop M-edge XANES as a valuable tool for measuring femtosecond dynamics of molecular transition metal complexes in the condensed phase.

Effect of γ- irradiation on structural, optical and electrical properties of thermally evaporated iron (III) chloride tetraphenylporphyrin thin films

Influence of γ-irradiation on structural, optical and electrical properties of thermally evaporated iron (III) chloride tetraphenylporphyrin (FeTPPCl) thin films have been reported. The structural features are investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The optical constants of as-deposited and γ-irradiated FeTPPCl thin films have been determined in the wavelength range 200–2500nm using spectrophotometric measurements at nearly normal incidence of light. The calculated values of the absorption coefficient,α, are used to estimate the type of transitions for as-deposited and γ-irradiated FeTPPCl thin films. The real part of the refractive index in the transparent region is discussed by using a single-oscillator and Drude models. According to Millerʼs rule, the single oscillator model is used to deduce the third-order nonlinear susceptibility, χ(3). The temperature dependence of DC electrical conductivity, σDC, confirms the semiconducting behaviour of FeTPPCl thin films. A free band type in the higher temperature region and hopping type in the low-temperature region have been used to explain the DC conduction mechanisms of FeTPPCl thin films.

Effect of illumination on thermally evaporated iron (III) chloride tetraphenylporphyrin thin organic films

Influence of illumination by a white light of incandescent lamp (150 W) on the optical properties of thermally evaporated iron (III) chloride tetraphenylporphyrin (FeTPPCl) thin films have been performed. The optical constants of As-deposited and illuminated FeTPPCl thin films have been determined in the wavelength range 400–2500 nm using spectrophotometric measurements at nearly normal incidence of light. The type of optical transitions for As-deposited and illuminated FeTPPCl thin films is ascertained from the spectral behavior of their absorption coefficient, α. The real part of the refractive index of As-deposited and illuminated FeTPPCl thin films in the region of optical transparency is analyzed basing on single-oscillator and Drude models. The third order nonlinear susceptibility, χ(3), of As-deposited and illuminated FeTPPCl thin films is obtained from the single-oscillator model and the Miller’s rule.

Influence of the Outer Ligands on Metal-to-Ligand Charge Transfer in Solvated Manganese Porphyrins.

Two manganese porphyrin complexes, manganese tetraphenylporphyrin chloride (MnTPP-Cl) and manganese octaethylporphyrin chloride (MnOEP-Cl), exhibit distinctive spectral features of metal-to-ligand charge-transfer (MLCT) when dissolved in dichloromethane, characterized by resonant inelastic X-ray scattering at the Mn L-edge and N K-edge. The metal-ligand orbital mixing that mediates the MLCT is analyzed with the help of density functional theory/restricted open-shell configuration interaction singles calculations. On the basis of experimental and theoretical analyses, the distinctive MLCT is argued to originate from alteration of the porphyrin outer ligands: phenyl groups in MnTPP-Cl and ethyl groups in MnOEP-Cl.

Energy cascades, excited state dynamics, and photochemistry in cob(III)alamins and ferric porphyrins.

Porphyrins and the related chlorins and corrins contain a cyclic tetrapyrrole with the ability to coordinate an active metal center and to perform a variety of functions exploiting the oxidation state, reactivity, and axial ligation of the metal center. These compounds are used in optically activated applications ranging from light harvesting and energy conversion to medical therapeutics and photodynamic therapy to molecular electronics, spintronics, optoelectronic thin films, and optomagnetics. Cobalt containing corrin rings extend the range of applications through photolytic cleavage of a unique axial carbon-cobalt bond, permitting spatiotemporal control of drug delivery. The photochemistry and photophysics of cyclic tetrapyrroles are controlled by electronic relaxation dynamics including internal conversion and intersystem crossing. Typically the electronic excitation cascades through ring centered ππ* states, ligand to metal charge transfer (LMCT) states, metal to ligand charge transfer (MLCT) states, and metal centered states. Ultrafast transient absorption spectroscopy provides a powerful tool for the investigation of the electronic state dynamics in metal containing tetrapyrroles. The UV-visible spectrum is sensitive to the oxidation state, electronic configuration, spin state, and axial ligation of the central metal atom. Ultrashort broadband white light probes spanning the range from 270 to 800 nm, combined with tunable excitation pulses, permit the detailed unravelling of the time scales involved in the electronic energy cascade. State-of-the-art theoretical calculations provide additional insight required for precise assignment of the states. In this Account, we focus on recent ultrafast transient absorption studies of ferric porphyrins and corrin containing cob(III)alamins elucidating the electronic states responsible for ultrafast energy cascades, excited state dynamics, and the resulting photoreactivity or photostability of these compounds. Iron tetraphenyl porphyrin chloride (Fe((III))TPPCl) exhibits picosecond decay to a metal centered d → d* (4)T state. This state decays on a ca. 16 ps time scale in room temperature solution but persists for much longer in a cryogenic glass. The photoreactivity of the (4)T state may lead to novel future applications for these compounds. In contrast, the nonplanar cob(III)alamins contain two axial ligands to the central cobalt atom. The upper axial ligand can be an alkyl group as in the two biologically active coenzymes or a nonalkyl ligand such as -CN in cyanocobalamin (vitamin B12) or -OH in hydroxocobalamin. The electronic structure, energy cascade, and bond cleavage of these compounds is sensitive to the details of the axial ligand. Nonalkylcobalamins exhibit ultrafast internal conversion to a low-lying state of metal to ligand or ligand to metal charge transfer character. The compounds are generally photostable with ground state recovery complete on a time scale of 2-7 ps in room temperature aqueous solution. Alkylcobalamins exhibit ultrafast internal conversion to an S1 state of d/π → π* character. Most compounds undergo bond cleavage from this state with near unit quantum yield within ∼100 ps. Recent theoretical calculations provide a potential energy surface accounting for these observations. Conformation dependent mixing of the corrin π and cobalt d orbitals plays a significant role in the observed photochemistry and photophysics.

Regarding initial ring opening of propylene oxide in its copolymerization with CO2 catalyzed by a cobalt(III) porphyrin complex.

Cobalt(III) tetraphenylporphyrin chloride (TPPCoCl) was experimentally proved to be an active catalyst for poly(propylene carbonate) production. It was chosen as a model catalyst in the present work to investigate the initiation step of propylene oxide (PO)/CO2 copolymerization, which is supposed to be the ring opening of the epoxide. Ring-opening intermediates (1-7) were detected by using (1) H NMR spectroscopy. A first-order reaction in TPPCoCl was determined. A combination of monometallic and bimetallic ring-opening pathways is proposed according to kinetics experiments. Addition of onium salts (e.g., bis(triphenylphosphine)iminium chloride, PPNCl) efficiently promoted the PO ring-opening rate. The existence of axial ligand exchange in the cobalt porphyrin complex in the presence of onium salts was suggested by analyzing collected (1) H NMR spectra.

Assistance of the iron porphyrin ligands to the binding interaction between the Fe center and small molecules in solution.

Solute-solvent electronic structure interactions of iron porphyrin at very low concentration in dichloromethane (CH2Cl2) liquid solution are reported. Two iron porphyrin complexes are investigated here-iron octaethylporphyrin chloride (FeOEP-Cl) and iron tetraphenylporphyrin chloride (FeTPP-Cl)-using X-ray absorption and emission spectroscopy at the Fe L2,3 edge, and spectra are interpreted with the help of density functional theory/restricted open-shell configuration interaction singles (DFT/ROCIS) calculations. It is argued that the Fe center of FeOEP-Cl is more capable of binding small solvent molecules, exemplified here for Cl2CH2, than FeTPP-Cl in solution. The proposed binding mechanism is through the assistance of the dipole interaction between the porphyrin-ligand system and the solvent molecule, in a situation where the ligand structure and arrangement maximize the binding interactions. Our studies demonstrate that even small ligands, depending on their structure and arrangement, can have considerable effects on porphyrin's metal center chemistry in liquid solution.

The Organism/Organic Exposure to Orbital Stresses (O/OREOS) Satellite: Radiation Exposure in Low-Earth Orbit and Supporting Laboratory Studies of Iron Tetraphenylporphyrin Chloride

We report results from the exposure of the metalloporphyrin iron tetraphenylporphyrin chloride (FeTPPCl) to the outer space environment, measured in situ aboard the Organism/Organic Exposure to Orbital Stresses nanosatellite. FeTPPCl was exposed for a period of 17 months (3700 h of direct solar exposure), which included broad-spectrum solar radiation (∼122 nm to the near infrared). Motivated by the potential role of metalloporphyrins as molecular biomarkers, the exposure of thin-film samples of FeTPPCl to the space environment in low-Earth orbit was monitored in situ via ultraviolet/visible spectroscopy and reported telemetrically. The space data were complemented by laboratory exposure experiments that used a high-fidelity solar simulator covering the spectral range of the spaceflight measurements. We found that thin-film samples of FeTPPCl that were in contact with a humid headspace gas (0.8-2.3% relative humidity) were particularly susceptible to destruction upon irradiation, degrading up to 10 times faster than identical thin films in contact with dry headspace gases; this degradation may also be related to the presence of oxides of nitrogen in those cells. In the companion terrestrial experiments, simulated solar exposure of FeTPPCl films in contact with either Ar or CO2:O2:Ar (10:0.01:1000) headspace gas resulted in growth of a band in the films' infrared spectra at 1961 cm(-1). We concluded that the most likely carriers of this band are allene (C3H4) and chloropropadiene (C3H3Cl), putative molecular fragments of the destruction of the porphyrin ring. The thin films studied in space and in solar simulator-based experiments show qualitatively similar spectral evolution as a function of contacting gaseous species but display significant differences in the time dependence of those changes. The relevance of our findings to planetary science, biomarker research, and the photostability of organic materials in astrobiologically relevant environments is discussed.