NO₂-induced synthesis of nitrato-iron(III) porphyrin with diverse coordination mode and the formation of isoporphyrin

Two nitrato-iron(III) porphyrinates [Fe(4-Me-TPP)(NO3)] 1 and [Fe(4-OMe-TPP)(NO3)] 2 are reported. Interestingly, [Fe(4-Me-TPP)(NO3)] 1 has nitrate ion coordinated as monodentate (by single oxygen atom), while [Fe(4-OMe-TPP)(NO3)] 2 has nitrate coordination through bidentate mode. Compound 1 was found serendipitously in the reaction of [Fe(4-Me-TPP)Cl] with nitrous acid, which was performed for the synthesis of nitro-iron(III) porphyrin, [Fe(4-Me-TPP)NO2]. The compound 2 was synthesized by passing NO2 gas through a solution of [Fe(4-OMe-TPP)]2O. Upon passing NO2 gas through a solution of a μ-oxo-dimer, [Fe(4-Me-TPP)]2O also produces 1. It is interesting that in more electron-rich porphyrin 2, binding of the nitrate in a symmetrical bidentate way while in less electron-rich porphyrin 1, binding of the anion is unidentate by a terminal oxygen atom. However, it is expected that the energy difference between the monodentate and bidentate coordination mode is very small and the interchange between these coordination is possible. Upon passing NO2 gas through a solution of μ -oxo-dimeric iron(III) porphyrin, the nitrato-iron(III) porphyrin forms first, that later gets oxidized to π-cation radical to yield hydroxy-isoporphyrin in the presence of trace amount of water. These nitrato-iron(III) porphyrinates in moist air slowly converted back to their respective μ -oxo-dimeric iron(III) porphyrins

Exploring The Relationship Between Biodiversity And Pollution In Natural History Studies

Natural history museums & libraries provide exceptional resources for both traditional & non-traditional education settings. Because they are snapshots in time & space, collections provide information that can never be duplicated. Learning about & interacting deeply with the living world is facilitated by exposure to collections. Specimens in collections allow for direct tracking of global biological diversity & also changes in that diversity, whether those changes are ancient or recent. This paper investigates the significance of biodiversity & pollution in the field of natural history studies, as well as the connection between the two concepts. It is emphasised here how the current rise in specimen-based digitization programmes has provided access to an unprecedented biodiversity data wealth, vastly expanding the scope of natural history collections. The methodology was used as a secondary source of data, which was gathered using online sources. By providing access tospecimens & data housed in natural history collections, online databases have allowed scientists along with the general public to address worldwide, regional, & also local concerns concerning biodiversity in a manner that was not conceivable a decade ago

Organizational level responses to the COVID-19 outbreak : challenges, strategies and framework for academic institutions

The outbreak of the novel coronavirus, severe acute respiratory syndrome (SARS)–CoV-2, has gained unprecedented global attention. SARS-CoV-2, which causes the newly described coronavirus disease 2019 (COVID-19), has affected millions of people and led to over 1.9 million deaths worldwide by the beginning of January 2021. Several governments have opted for lockdown as one of the measures to combat the rapidly increasing number of COVID-19 cases. Academic institutions (i.e., universities, colleges, research centers and national laboratories), which are home to thousands of students, researchers, technicians, and administrative staff, have strictly followed government regulations. Due to the lockdown, the majority of academics have been facing various challenges, especially in transitioning from classroom to remote teaching and conducting research activities from a home office. This article from an early-career researchers’ perspective addresses the common challenges that academic institutions have encountered and possible strategies they have adopted to mitigate those challenges at the individual organizational level. Furthermore, we propose a framework to facilitate the handling of such crisis in any near future at the organizational level. We hope academics, policymakers and (non) government organizations across the globe will find this perspective a call to better improve the overall infrastructure of academic institutions

Oxidative degradation of zinc porphyrin in comparison with its iron analogue

Zinc hydroxyisoporphyrin (2), under sunlight and argon, is reduced back to zinc meso-tetraphenylporphyrin (1), but stays stable in oxygen in the absence of light. This behavior is in contrast to its iron analogue and stresses the redox role of iron in heme degradation. Compound 2 also responds to chlorophyll-type degradation (3) under sunlight and oxygen

Self-assembly of magnesium and zinc trimethoxyphenylporphyrin polymer as nanospheres and nanorods

The crystal structures of [Mg(TMPP)] (1) and [Zn(TMPP)] (2) (TMPP = 3,4,5-trimethoxyphenylporphyrin) show that 1 and 2 possess unusual one-dimensional (1D) coordination polymer structure through metal–oxygen (oxygen atom from m-methoxy group of adjacent porphyrin) bonds. In 1 and 2, the metal ion is hexa-coordinated with the two axially ligated methoxy groups (bonded through oxygen) from the two neighboring porphyrins. In the nano domain, the self-organization of 1 in dichloromethane (DCM)–petroleum ether is in a spherical shape. Complex 2 self-organizes as a nanorod in DCM–petroleum ether medium. In DCM or in chloroform, such a self-organization process, which is influenced by air bubble formation, transforms the rod to a circular ring. In coordinating solvent like ethanol, the polymer aggregation is terminated in both 1 and 2 to produce relatively large rectangles. The varied ways of self-organization in the nanodomain of these two porphyrins have been discussed

Nitrous-acid-mediated synthesis of iron-nitrosyl-porphyrin: pH-dependent release of nitric oxide

Two iron–nitrosyl–porphyrins, nitrosyl[<em>meso</em>-tetrakis(3,4,5-trimethoxyphenylporphyrin]iron(II) acetic acid solvate (3) and nitrosyl[<em>meso</em>-tetrakis(4-methoxyphenylporphyrin]iron(II) CH₂Cl₂ solvate (4), were synthesized in quantitative yield by using a modified procedure with nitrous acid, followed by oxygen-atom abstraction by triphenylphosphine under an argon atmosphere. These nitrosyl porphyrins are in the {FeNO}⁷ class. Under an argon atmosphere, these compounds are relatively stable over a broad range of pH values (4–8) but, under aerobic conditions, they release nitric oxide faster at high pH values than that at low pH values. The generated nitric-oxide-free iron(III)–porphyrin can be re-nitrosylated by using nitrous acid and triphenylphosphine. The rapid release of NO from these Fe^II complexes at high pH values seems to be similar to that in nitrophorin, a nitric-oxide-transport protein, which formally possesses Fe^III. However, because the release of NO occurs from ferrous–nitrosyl–porphyrin under aerobic conditions, these compounds are more closely related to nitrobindin, a recently discovered heme protein

A magnesium porphyrin bicarbonate complex with CO<SUB>2</SUB>-modulated photosystem I action

Light to chemical energy: Magnesium tetraphenylporphyrin (MgTPP; 1), upon treatment with [Bu4N]OH under a CO2 atmosphere, formed its bicarbonate adduct, [Bu4N][HCO3MgTPP] (2). Compound 2 is electrochemically oxidized at a lower potential than that of 1; under light illumination, it drops to an even lower value, resulting in a more facile electron release

NO<SUB>2</SUB>-mediated meso-hydroxylation of iron(III) porphyrin

&#183; NO2 generated from &#183; NO and air add to iron(III) porphyrin upon nitration, which isomerized spontaneously to hydrolysis, yielding a meso-hydroxylated cation that seized by the end oxidation product, a nitrate ion, through extensive hydrogen bonding

Large-scale synthesis of soluble graphitic hollow carbon nanorods with tunable photoluminescence for the selective fluorescent detection of DNA

Photoluminescent water-soluble hollow carbon nanorods were synthesized by the pyrolysis of castor oil seeds (Ricinus communis) without the use of a catalyst. Oxidation of the pyrolysed soot produced a water-soluble form of graphitic hollow carbon nanorods. These showed excitation-dependent multicoloured photoluminescent emission from the green to red region of the visible spectrum and extending to the near-infrared region. This photoluminescent behaviour was used to produce a fluorescent turn-off/turn-on sensor for the specific, sensitive and rapid determination of DNA with a detection limit of ∼1.14 nM