A Thioether-Ligated Cupric Superoxide Model with Hydrogen Atom Abstraction Reactivity.

The central role of cupric superoxide intermediates proposed in hormone and neurotransmitter biosynthesis by noncoupled binuclear copper monooxygenases like dopamine-ß-monooxygenase has drawn significant attention to the unusual methionine ligation of the CuM ("CuB") active site characteristic of this class of enzymes. The copper-sulfur interaction has proven critical for turnover, raising still-unresolved questions concerning Nature's selection of an oxidizable Met residue to facilitate C-H oxygenation. We describe herein a model for CuM, [(TMGN3S)CuI]+ ([1]+), and its O2-bound analog [(TMGN3S)CuII(O2•-)]+ ([1·O2]+). The latter is the first reported cupric superoxide with an experimentally proven Cu-S bond which also possesses demonstrated hydrogen atom abstraction (HAA) reactivity. Introduction of O2 to a precooled solution of the cuprous precursor [1]B(C6F5)4 (-135 °C, 2-methyltetrahydrofuran (2-MeTHF)) reversibly forms [1·O2]B(C6F5)4 (UV/vis spectroscopy: λmax 442, 642, 742 nm). Resonance Raman studies (413 nm) using 16O2 [18O2] corroborated the identity of [1·O2]+ by revealing Cu-O (446 [425] cm-1) and O-O (1105 [1042] cm-1) stretches, and extended X-ray absorption fine structure (EXAFS) spectroscopy showed a Cu-S interatomic distance of 2.55 Å. HAA reactivity between [1·O2]+ and TEMPO-H proceeds rapidly (1.28 × 10-1 M-1 s-1, -135 °C, 2-MeTHF) with a primary kinetic isotope effect of kH/kD = 5.4. Comparisons of the O2-binding behavior and redox activity of [1]+ vs [2]+, the latter a close analog of [1]+ but with all N atom ligation (i.e., N3S vs N4), are presented.

Intramolecular Hydrogen Bonding Enhances Stability and Reactivity of Mononuclear Cupric Superoxide Complexes.

[(L)CuII(O2•-)]+ (i.e., cupric-superoxo) complexes, as the first and/or key reactive intermediates in (bio)chemical Cu-oxidative processes, including in the monooxygenases PHM and DßM, have been systematically stabilized by intramolecular hydrogen bonding within a TMPA ligand-based framework. Also, gradual strengthening of ligand-derived H-bonding dramatically enhances the [(L)CuII(O2•-)]+ reactivity toward hydrogen-atom abstraction (HAA) of phenolic O-H bonds. Spectroscopic properties of the superoxo complexes and their azido analogues, [(L)CuII(N3-)]+, also systematically change as a function of ligand H-bonding capability.

In vitro and in vivo reduction of post-prandial blood glucose levels by ethyl alcohol and water Zingiber mioga extracts through the inhibition of carbohydrate hydrolyzing enzymes.

BACKGROUND: Type 2 diabetes is a serious problem for developed and developing countries. Prevention of prediabetes progression to type 2 diabetes with the use of natural products appears to be a cost-effective solution. Zingiber mioga has been used as a traditional food in Asia. Recent research has reported the potential health benefits of Zingiber mioga, but the blood glucose reducing effect has not been yet evaluated. METHODS: In this study Zingiber mioga extracts (water and ethanol) were investigated for their anti-hyperglycemic and antioxidant potential using both in vitro and animal models. The in vitro study evaluated the total phenolic content, the oxygen radical absorbance capacity (ORAC) and the inhibitory effect against carbohydrate hydrolyzing enzymes (porcine pancreatic α-amylase and rat intestinal sucrase and maltase) of both Zingiber mioga extracts. Also, the extracts were evaluated for their in vivo post-prandial blood glucose reducing effect using SD rat and db/db mice models. RESULTS: Our findings suggest that the ethanol extract of Zingiber mioga (ZME) exhibited the higher sucrase and maltase inhibitory activity (IC50, 3.50 and 3.13 mg/mL) and moderate α-amylase inhibitory activity (IC50, >10 mg/mL). Additionally, ZME exhibited potent peroxyl radical scavenging linked antioxidant activity (0.53/TE 1 µM). The in vivo study using SD rat and db/db mice models also showed that ZME reduces postprandial increases of blood glucose level after an oral administration of sucrose by possibly acting as an intestinal α-glucosidase inhibitor (ZME 0.1 g/kg 55.61 ± 13.24 mg/dL) CONCLUSION: The results indicate that Zingiber mioga extracts exhibited significant in vitro α-glucosidase inhibition and antioxidant activity. Additionally, the tested extracts demonstrated in vivo anti-hyperglycemic effects using SD rat and db/db mice models. Our findings provide a strong rationale for the further evaluation of Zingiber mioga for the potential to contribute as a useful dietary strategy to manage postprandial hyperglycemia.

Seroepidemiological Survey of Zoonotic Diseases in Small Mammals with PCR Detection of Orientia tsutsugamushi in Chiggers, Gwangju, Korea.

Serosurveillance for zoonotic diseases in small mammals and detection of chiggers, the vector of Orientia tsutsugamushi, were conducted from September 2014 to August 2015 in Gwangju Metropolitan Area. Apodemus agrarius was the most commonly collected small mammals (158; 91.8%), followed by Myodes regulus (8; 4.6%), and Crocidura lasiura (6; 3.5%). The highest seroprevalence of small mammals for O. tsutsugamushi (41; 26.3%) was followed by hantaviruses (24; 15.4%), Rickettsia spp. (22; 14.1%), and Leptospira (2; 1.3%). A total of 3,194 chiggers were collected from small mammals, and 1,236 of 3,194 chiggers were identified with 7 species of 3 genera: Leptotrombidium scutellare was the most commonly collected species (585; 47.3%), followed by L. orientale (422; 34.1%), Euchoengastia koreaensis (99; 8.0%), L. palpale (58; 4.7%), L. pallidum (36; 2.9%), Neotrombicula gardellai (28; 2.3%), and L. zetum (8; 0.6%). L. scutellare was the predominant species. Three of 1,236 chigger mites were positive for O. tsutsugamushi by PCR. As a result of phylogenetic analysis, the O. tsutsugamushi strain of chigger mites had sequence homology of 90.1-98.2% with Boryong. This study provides baseline data on the distribution of zoonotic diseases and potential vectors for the development of prevention strategies of vector borne diseases in Gwangju metropolitan area.

Amine oxidative N-dealkylation via cupric hydroperoxide Cu-OOH homolytic cleavage followed by site-specific fenton chemistry.

Copper(II) hydroperoxide species are significant intermediates in processes such as fuel cells and (bio)chemical oxidations, all involving stepwise reduction of molecular oxygen. We previously reported a Cu(II)-OOH species that performs oxidative N-dealkylation on a dibenzylamino group that is appended to the 6-position of a pyridyl donor of a tripodal tetradentate ligand. To obtain insights into the mechanism of this process, reaction kinetics and products were determined employing ligand substrates with various para-substituent dibenzyl pairs (-H,-H; -H,-Cl; -H,-OMe, and -Cl,-OMe), or with partially or fully deuterated dibenzyl N-(CH2Ph)2 moieties. A series of ligand-copper(II) bis-perchlorate complexes were synthesized, characterized, and the X-ray structures of the -H,-OMe analogue were determined. The corresponding metastable Cu(II)-OOH species were generated by addition of H2O2/base in acetone at -90 °C. These convert (t1/2 ≈ 53 s) to oxidatively N-dealkylated products, producing para-substituted benzaldehydes. Based on the experimental observations and supporting DFT calculations, a reaction mechanism involving dibenzylamine H-atom abstraction or electron-transfer oxidation by the Cu(II)-OOH entity could be ruled out. It is concluded that the chemistry proceeds by rate limiting Cu-O homolytic cleavage of the Cu(II)-(OOH) species, followed by site-specific copper Fenton chemistry. As a process of broad interest in copper as well as iron oxidative (bio)chemistries, a detailed computational analysis was performed, indicating that a Cu(I)OOH species undergoes O-O homolytic cleavage to yield a hydroxyl radical and Cu(II)OH rather than heterolytic cleavage to yield water and a Cu(II)-O(•-) species.

A N3S(thioether)-ligated Cu(II)-superoxo with enhanced reactivity.

Previous efforts to synthesize a cupric superoxide complex possessing a thioether donor have resulted in the formation of an end-on trans-peroxo-dicopper(II) species, [{(Ligand)Cu(II)}2(µ-1,2-O2(2-))](2+). Redesign/modification of previous N3S tetradentate ligands has now allowed for the stabilization of the monomeric, superoxide product possessing a S(thioether) ligation, [((DMA)N3S)Cu(II)(O2(•-))](+) (2(S)), as characterized by UV-vis and resonance Raman spectroscopies. This complex mimics the putative Cu(II)(O2(•-)) active species of the copper monooxygenase PHM and exhibits enhanced reactivity toward both O-H and C-H substrates in comparison to close analogues [(L)Cu(II)(O2(•-))](+), where L contains only nitrogen donor atoms. Also, comparisons of [(L)Cu(II/I)](n+) compound reduction potentials (L = various N4 vs (DMA)N3S ligands) provide evidence that (DMA)N3S is a weaker donor to copper ion than is found for any N4 ligand-complex.

Copper-peptide complex structure and reactivity when found in conserved His-X(aa)-His sequences.

Oxygen-activating copper proteins may possess His-X(aa)-His chelating sequences at their active sites and additionally exhibit imidiazole group δN vs εN tautomeric preferences. As shown here, such variations strongly affect copper ion's coordination geometry, redox behavior, and oxidative reactivity. Copper(I) complexes bound to either δ-HGH or ε-HGH tripeptides were synthesized and characterized. Structural investigations using X-ray absorption spectroscopy, density functional theory calculations, and solution conductivity measurements reveal that δ-HGH forms the Cu(I) dimer complex [{Cu(I)(δ-HGH)}2](2+) (1) while ε-HGH binds Cu(I) to give the monomeric complex [Cu(I)(ε-HGH)](+) (2). Only 2 exhibits any reactivity, forming a strong CO adduct, [Cu(I)(ε-HGH)(CO)](+), with properties closely matching those of the copper monooxygenase PHM. Also, 2 is reactive toward O2 or H2O2, giving a new type of O2-adduct or Cu(II)-OOH complex, respectively.

Mechanistic insights into the oxidation of substituted phenols via hydrogen atom abstraction by a cupric-superoxo complex.

To obtain mechanistic insights into the inherent reactivity patterns for copper(I)-O2 adducts, a new cupric-superoxo complex [(DMM-tmpa)Cu(II)(O2(•-))](+) (2) [DMM-tmpa = tris((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)amine] has been synthesized and studied in phenol oxidation-oxygenation reactions. Compound 2 is characterized by UV-vis, resonance Raman, and EPR spectroscopies. Its reactions with a series of para-substituted 2,6-di-tert-butylphenols (p-X-DTBPs) afford 2,6-di-tert-butyl-1,4-benzoquinone (DTBQ) in up to 50% yields. Significant deuterium kinetic isotope effects and a positive correlation of second-order rate constants (k2) compared to rate constants for p-X-DTBPs plus cumylperoxyl radical reactions indicate a mechanism that involves rate-limiting hydrogen atom transfer (HAT). A weak correlation of (k(B)T/e) ln k2 versus E(ox) of p-X-DTBP indicates that the HAT reactions proceed via a partial transfer of charge rather than a complete transfer of charge in the electron transfer/proton transfer pathway. Product analyses, (18)O-labeling experiments, and separate reactivity employing the 2,4,6-tri-tert-butylphenoxyl radical provide further mechanistic insights. After initial HAT, a second molar equiv of 2 couples to the phenoxyl radical initially formed, giving a Cu(II)-OO-(ArO') intermediate, which proceeds in the case of p-OR-DTBP substrates via a two-electron oxidation reaction involving hydrolysis steps which liberate H2O2 and the corresponding alcohol. By contrast, four-electron oxygenation (O-O cleavage) mainly occurs for p-R-DTBP which gives (18)O-labeled DTBQ and elimination of the R group.

Deflection of resilient materials for reduction of floor impact sound.

Recently, many residents living in apartment buildings in Korea have been bothered by noise coming from the houses above. In order to reduce noise pollution, communities are increasingly imposing bylaws, including the limitation of floor impact sound, minimum thickness of floors, and floor soundproofing solutions. This research effort focused specifically on the deflection of resilient materials in the floor sound insulation systems of apartment houses. The experimental program involved conducting twenty-seven material tests and ten sound insulation floating concrete floor specimens. Two main parameters were considered in the experimental investigation: the seven types of resilient materials and the location of the loading point. The structural behavior of sound insulation floor floating was predicted using the Winkler method. The experimental and analytical results indicated that the cracking strength of the floating concrete floor significantly increased with increasing the tangent modulus of resilient material. The deflection of the floating concrete floor loaded at the side of the specimen was much greater than that of the floating concrete floor loaded at the center of the specimen. The Winkler model considering the effect of modulus of resilient materials was able to accurately predict the cracking strength of the floating concrete floor.

NSrp70 is a novel nuclear speckle-related protein that modulates alternative pre-mRNA splicing in vivo.

Nuclear speckles are known to be the storage sites of mRNA splicing regulators. We report here the identification and characterization of a novel speckle protein, referred to as NSrp70, based on its subcellular localization and apparent molecular weight. This protein was first identified as CCDC55 by the National Institutes of Health Mammalian Gene Collection, although its function has not been assigned. NSrp70 was colocalized and physically interacted with SC35 and ASF/SF2 in speckles. NSrp70 has a putative RNA recognition motif, the RS-like region, and two coiled-coil domains, suggesting a role in RNA processing. Accordingly, using CD44, Tra2ß1 and Fas constructs as splicing reporter minigenes, we found that NSrp70 modulated alternative splice site selection in vivo. The C-terminal 10 amino acids (531-540), including (536)RD(537), were identified as a novel nuclear localization signal, and the region spanning 290-471 amino acids was critical for speckle localization and binding to SC35 and ASF/SF2. The N-terminal region (107-161) was essential for the pre-mRNA splicing activity. Finally, we found that knockout of NSrp70 gene in mice led to a lack of progeny, including fetal embryos. Collectively, we demonstrate that NSrp70 is a novel splicing regulator and essentially required early stage of embryonic development.

Synthesis, structural, and spectroscopic characterization and reactivities of mononuclear cobalt(III)-peroxo complexes.

Metal-dioxygen adducts are key intermediates detected in the catalytic cycles of dioxygen activation by metalloenzymes and biomimetic compounds. In this study, mononuclear cobalt(III)-peroxo complexes bearing tetraazamacrocyclic ligands, [Co(12-TMC)(O(2))](+) and [Co(13-TMC)(O(2))](+), were synthesized by reacting [Co(12-TMC)(CH(3)CN)](2+) and [Co(13-TMC)(CH(3)CN)](2+), respectively, with H(2)O(2) in the presence of triethylamine. The mononuclear cobalt(III)-peroxo intermediates were isolated and characterized by various spectroscopic techniques and X-ray crystallography, and the structural and spectroscopic characterization demonstrated unambiguously that the peroxo ligand is bound in a side-on η(2) fashion. The O-O bond stretching frequency of [Co(12-TMC)(O(2))](+) and [Co(13-TMC)(O(2))](+) was determined to be 902 cm(-1) by resonance Raman spectroscopy. The structural properties of the CoO(2) core in both complexes are nearly identical; the O-O bond distances of [Co(12-TMC)(O(2))](+) and [Co(13-TMC)(O(2))](+) were 1.4389(17) Å and 1.438(6) Å, respectively. The cobalt(III)-peroxo complexes showed reactivities in the oxidation of aldehydes and O(2)-transfer reactions. In the aldehyde oxidation reactions, the nucleophilic reactivity of the cobalt-peroxo complexes was significantly dependent on the ring size of the macrocyclic ligands, with the reactivity of [Co(13-TMC)(O(2))](+) > [Co(12-TMC)(O(2))](+). In the O(2)-transfer reactions, the cobalt(III)-peroxo complexes transferred the bound peroxo group to a manganese(II) complex, affording the corresponding cobalt(II) and manganese(III)-peroxo complexes. The reactivity of the cobalt-peroxo complexes in O(2)-transfer was also significantly dependent on the ring size of tetraazamacrocycles, and the reactivity order in the O(2)-transfer reactions was the same as that observed in the aldehyde oxidation reactions.

Synthesis and antifungal activity of benzofuran-5-ols.

Benzofuran-5-ol derivatives were synthesized and tested for in vitro antifungal activity against Candida, Aspergillus species, and Cryptococcus neoformans. Among them tested, many benzofuran-5-ols showed good antifungal activity. The results suggest that benzofuran-5-ols would be promising antifungal agents.

Shear Performance of Reinforced Concrete Beams with Small Circular Openings Strengthened Using Rectangular and Octagonal-Shaped Reinforcement.

An experimental case study was carried out to investigate the shear performance of reinforced concrete beams with small circular openings under a cyclic anti-symmetric bending moment. The openings were strengthened by using a newly developed reinforcement continuously bent into rectangular and octagonal shapes, which was convenient for installation and effective for crack control. The presence of web opening reinforcement, the reinforcing method, and the web opening spacing were employed as main variables in the design of five specimens. The cyclic performance of all specimens was evaluated in terms of failure mode, crack pattern, strength and stiffness degradation, and strain distribution. Experimental results were discussed to assess the suitability of the proposed web opening reinforcement in RC web opening beams. It was confirmed that the proposed web opening reinforcement exhibited outstanding crack control and served as a shear resistance component in place of the concrete cross-section lost due to web openings. Finally, the shear strength of all specimens, obtained from the cyclic loading tests, were compared with those obtained from the equation proposed by Mansur (1998) and the Architectural Institute of Japan standard 2010.

Hydrogen-atom abstraction reactions by manganese(V)- and manganese(IV)-oxo porphyrin complexes in aqueous solution.

High-valent manganese(IV or V)-oxo porphyrins are considered as reactive intermediates in the oxidation of organic substrates by manganese porphyrin catalysts. We have generated Mn(V)- and Mn(IV)-oxo porphyrins in basic aqueous solution and investigated their reactivities in C-H bond activation of hydrocarbons. We now report that Mn(V)- and Mn(IV)-oxo porphyrins are capable of activating C-H bonds of alkylaromatics, with the reactivity order of Mn(V)-oxo>Mn(IV)-oxo; the reactivity of a Mn(V)-oxo complex is 150 times greater than that of a Mn(IV)-oxo complex in the oxidation of xanthene. The C-H bond activation of alkylaromatics by the Mn(V)- and Mn(IV)-oxo porphyrins is proposed to occur through a hydrogen-atom abstraction, based on the observations of a good linear correlation between the reaction rates and the C-H bond dissociation energy (BDE) of substrates and high kinetic isotope effect (KIE) values in the oxidation of xanthene and dihydroanthracene (DHA). We have demonstrated that the disproportionation of Mn(IV)-oxo porphyrins to Mn(V)-oxo and Mn(III) porphyrins is not a feasible pathway in basic aqueous solution and that Mn(IV)-oxo porphyrins are able to abstract hydrogen atoms from alkylaromatics. The C-H bond activation of alkylaromatics by Mn(V)- and Mn(IV)-oxo species proceeds through a one-electron process, in which a Mn(IV)-oxo porphyrin is formed as a product in the C-H bond activation by a Mn(V)-oxo porphyrin, followed by a further reaction of the Mn(IV)-oxo porphyrin with substrates that results in the formation of a Mn(III) porphyrin complex. This result is in contrast to the oxidation of sulfides by the Mn(V)-oxo porphyrin, in which the oxidation of thioanisole by the Mn(V)-oxo complex produces the starting Mn(III) porphyrin and thioanisole oxide. This result indicates that the oxidation of sulfides by the Mn(V)-oxo species occurs by means of a two-electron oxidation process. In contrast, a Mn(IV)-oxo porphyrin complex is not capable of oxidizing sulfides due to a low oxidizing power in basic aqueous solution.

High-valent manganese(v)-oxo porphyrin complexes in hydride transfer reactions.

Hydride transfer from dihydronicotinamide adenine dinucleotide (NADH) analogues to trans-dioxomanganese(v) porphyrin complexes proceeds via proton-coupled electron transfer, followed by rapid electron transfer.

Synthesis and antifungal activity of 1H-pyrrolo[3,2-g]quinoline-4,9-diones and 4,9-dioxo-4,9-dihydro-1H-benzo[f]indoles.

1H-Pyrrolo[3,2-g]quinoline-4,9-diones and 4,9-dioxo-4,9-dihydro-1H-benzo[f]indoles were synthesized and tested for in vitro antifungal activity against fungi. Among them tested, many compounds showed good antifungal activity. The results suggest that 1H-pyrrolo[3,2-g]quinoline-4,9-diones and 4,9-dioxo-4,9-dihydro-1H-benzo[f]indoles would be potent antifungal agents.

Investigation on STR profiling of maternal DNA from a degraded placenta with an abandoned newborn male baby.

The placenta is a unique and complex organ composed of a mixture of fetal and maternal tissues. In this study, we aimed to detect maternal short tandem repeats (STRs) in degraded placenta from a newborn male baby found abandoned in a river. In order to deduce maternal alleles-which was not possible by sampling of different parts of the placenta-we collected samples from the maternal blood pool in the intervillous space and applied a multi-step method (named tempo-gap DNA extraction) for extracting DNA at defined time points after cell lysis (10 min, 2 h 10 min, and 4 h 10 min). The first lysis step (10 min) effectively removed severely degraded DNA; this was followed by a second lysis step (2 h 10 min) for high recovery of both fetal and maternal DNA. The third lysis step (4 h 10 min) effectively eliminated unwanted residual fetal DNA. The differential lysis of fetal and maternal cells occurred not because fetal and maternal cells exhibited different lysis behavior, but because of the difference in their numbers. Although all of the lysates showed fetal cell contamination, we were able to derive a maternal STR profile from the good-quality mixed STR profile from the second lysate of placental piece B. This study provides technical insight into concurrent issues encountered during routine forensic analysis of DNA samples, such as degradation, cell contamination (mixed DNA), and low-template DNA.

Relationship between Health Behaviors and Marital Adjustment and Marital Intimacy in Multicultural Family Female Immigrants.

BACKGROUND: This study analyzed the relationship between health behaviors and marital adjustment in multicultural couples to evaluate their health status. METHODS: Married couples (70 Korean men and their immigrant wives) completed a structured interview on health behaviors and sociodemographic factors, the Revised Dyadic Adjustment Scale (RDAS), and the Marital Intimacy Scale. Based on the cutoff value of the RDAS, respondents were classified into two groups: high or low dyadic adaptation groups. The collected data were compared with health behavior regarding smoking, alcohol consumption, exercise, and weight. RESULTS: The odds ratio (OR) (95% confidence interval [CI]) by logistic regression with adjustment for age, educational level, career, occupation, length of residence in Korea, nationality, religion, age difference between couple, number of children, monthly income, and proficiency in Korean was 1.279 (1.113-1.492) for unhealthy exercise and 1.732 (1.604-1.887) for unhealthy body weight in female immigrants with low marital adjustment. In Korean husbands with low marital adjustment, the OR (95% CI) was 1.625 (1.232-2.142) for smoking and 1.327 (1.174- 1.585) for unhealthy exercise. No significant relationship was found between marital intimacy and health behaviors in female immigrants or Korean husbands. CONCLUSION: More desirable health behaviors were observed in highly adapted couples. Therefore, family physicians should be concerned with marital adjustment and other associative factors to evaluate and improve multicultural couples' health status.

Direct evidence for an iron(IV)-oxo porphyrin pi-cation radical as an active oxidant in catalytic oxygenation reactions.

A high-valent iron(IV)-oxo porphyrin pi-cation radical is an active oxidant in the catalytic oxygenation of organic substrates by an iron(III) porphyrin complex and peracids, whereas an iron(III)-oxidant porphyrin adduct is a sluggish oxidant in iron porphyrin model reactions.

A structurally-characterized peroxomanganese(iv) porphyrin from reversible O2 binding within a metal-organic framework.

The role of peroxometal species as reactive intermediates in myriad biological processes has motivated the synthesis and study of analogous molecular model complexes. Peroxomanganese(iv) porphyrin complexes are of particular interest, owing to their potential ability to form from reversible O2 binding, yet have been exceedingly difficult to isolate and characterize in molecular form. Alternatively, immobilization of metalloporphyrin sites within a metal-organic framework (MOF) can enable the study of interactions between low-coordinate metal centers and gaseous substrates, without interference from bimolecular reactions and axial ligation by solvent molecules. Here, we employ this approach to isolate the first rigorously four-coordinate manganese(ii) porphyrin complex and examine its reactivity with O2 using infrared spectroscopy, single-crystal X-ray diffraction, EPR spectroscopy, and O2 adsorption analysis. X-ray diffraction experiments reveal for the first time a peroxomanganese(iv) porphyrin species, which exhibits a side-on, η2 binding mode. Infrared and EPR spectroscopic data confirm the formulation of a peroxomanganese(iv) electronic structure, and show that O2 binding is reversible at ambient temperature, in contrast to what has been observed in molecular form. Finally, O2 gas adsorption measurements are employed to quantify the enthalpy of O2 binding as hads = -49.6(8) kJ mol-1. This enthalpy is considerably higher than in the corresponding Fe- and Co-based MOFs, and is found to increase with increasing reductive capacity of the MII/III redox couple.