Encapsulation of iron(III) protoporphyrin IX and tetraphenylporphyrin in metal-organic frameworks for application as heterogeneous oxidation catalysts

Two MOFs, [H2N(CH3)2][Zn3(TATB2(HCOO)]·HN(CH3)2·DMF·6H2O (1) and ZnHKUST-1 (2) (TATB = 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoate) were investigated as potential hosts to encapsulate Fe(III) protoporphyrin IX (ferrihaem = Fe(III)PPIX) and Fe(III) tetraphenylporphyrin (Fe(III)TPP). Methyl orange (MO) adsorption was used as an initial model for substrate uptake in MOFs 1 and 2. MOF 1 showed good adsorption of MO (10.3 ± 0.8 mg.g-1 ) which could undergo in situ protonation upon exposure to aqueous HCl vapour. By contrast MO uptake by 2 was much lower (2 ± 1 mg.g-1 ) and PXRD indicated structural instability on exposure to water was the likely cause. Two methods for Fe(III)PPIX incorporation into 1 were investigated: soaking and encapsulation. Encapsulation was verified by SEM-EDS and showed comparable concentrations of Fe(III)PPIX on exposed interior surfaces and on the original surface of fractured crystals. SEM EDS results were consistent with ICP-OES data on bulk material (1.2 ± 0.1 mass % Fe). PXRD data showed that the framework in 1 was unchanged after encapsulation of Fe(III)PPIX. MO adsorption (6 ± 1 mg.g1 ) by Fe(III)PPIX-1 confirmed there is space for substrate diffusion into the framework, while the UV-visible spectrum of solubilized crystals confirmed that Fe(III)PPIX retained its integrity. A solid-state UV-visible spectrum of Fe(III)PPIX-1 indicated that Fe(III)PPIX was not in a µ-oxo dimeric form. Although single-crystal XRD data did not allow for full refinement of the encapsulated Fe(III)PPIX molecule owing to disorder of the metalloporphyrin, the Fe atom and pyrrole N atoms were located, enabling rigid-body modelling of the porphine core. For comparison, Fe(III)PPIX was further encapsulated in 2, forming Fe(III)PPIX-2. Reaction ABSTRACT of 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) with H2O2, catalysed by Fe(III)PPIX-1 and -2 showed that Fe(III)PPIX-1 is significantly more efficient than Fe(III)PPIX-2 and is superior to solid Fe(III)PPIX-Cl due to the faster initial rate of reaction as well as the greater conversion of ABTS to ABTS●+ . Both frameworks 1 and 2 were also investigated as potential hosts to encapsulate Fe(III) tetraphenylporphyrin (Fe(III)TPP). Attempts to encapsulate Fe(III)TPP into 1 were unsuccessful, but Fe(III)TPP was successfully encapsulated into 2, forming Fe(III)TPP-2. The framework was characterised by PXRD and SEM-EDS confirmed uniform distribution of Fe(III)TPP through the framework. The loading of Fe(III)TPP determined using ICP-OES (0.604 ± 0.008 Fe mass %) agreed well with SEM-EDS data. Single crystals of Fe(III)TPP-2 were obtained and structure determination showed that the Fe(III) porphyrin was positionally disordered over three positions. The instability of Fe(III)TPP-2 in the presence of H2O resulted in it being an inappropriate choice as an oxidation catalyst. The kinetics of ABTS oxidation by H2O2 catalysed by Fe(III)PPIX-1 were further investigated. The peroxidatic activity of this heterogeneous system conforms to a rate law identical to that observed in solution with no discernible influence of particle size, suggesting that the MOF system closely mimics the solution state. The proposed rate law indicates a reaction mechanism with two possible pathways, as suggested for the same reaction in solution. The major pathway describes the coordination of H2O2 to the Fe(III) centre and subsequent formation of a high valent intermediate, while the minor pathway describes the same process preceded by ABTS coordination to the Fe(III) centre forming a six-coordinate complex. The further application of Fe(III)PPIX-1 as an oxidation catalyst was probed by investigating the catalytic oxidation of hydroquinone, thymol, benzyl alcohol and phenyl ethanol by tert-butyl-hydroperoxide ( tBuOOH). Reactions were successful and showed t1/2 values that increase with increasing substrate molecular volume

Political Dimension of Policy Implementation in Rufus Giwa Polytechnic, Owo, Ondo State, Nigeria

Despite the importance of higher education and the role it plays in national development, higher education is experiencing downward trends in Ondo State, Nigeria. This perhaps explains the proliferation of literature on higher education subsector but there has to date been little systematic evaluation of the consequences of political influence on policy implementation in Rufus Giwa Polytechnic, Owo. This article assesses the political context of policy implementation in Rufus Giwa Polytechnic, Owo. Using qualitative method, this article finds evidence of political interference in the implementation of recruitment and funding policies of the polytechnic as the major factor responsible for the low performance in the polytechnic. The findings are relevant both for understanding the political context of policy implementation and also for providing the necessary strategies for effective policy implementation in the polytechnic in particular and higher education subsector in Ondo State, Nigeria in general

The Operator’s Guide For Minimizing Energy Costs

The consumption of petroleum by transportation activities is increasing despite the finite limits on its supply. This paper concentrates on the motor vehicle driver, his driving habits, and guides to reduced fuel consumption which would enable the individual to curtail wasteful practices with respect to vehicle operation

Democracy, political participation and good governance in Nigeria

The practice of democracy in Nigeria over a decade ago has not yielded much needed good governance. This is because democracy is practiced in such a way that responsible and competent people are scared away. Scholars and keen observers have attempted at unraveling the factors militating against translating democracy into good governance. The paper revealed that democratisation in Nigeria is pervaded by electoral violence, manipulation of election results and political participation constraints. These identified challenges have made it impossible to attain consolidated democracy that can, in turn, facilitate good governance. Democracy is a catalyst for accountability, transparency and responsive government which brings about good governance. The paper insisted that governance collapse in Nigeria is reflexive of the perfunctory role of the political actors and it adopted elite theory to reinforce this argument. The paper adopted content analysis as a means of data gathering. It dwelt extensively on the synergy between democracy, political participation and good governance but queried the artificial gulf between them in Nigeria. It concluded by putting forth viable and pragmatic way forward

Predicting Secure Detention Placement for African-American Juvenile Offenders: Addressing the Disproportionate Minority Confinement Problem

Disproportionate minority contact and confinement (DMC) are significant problems within the juvenile justice system in the United States. Minority youth are more often arrested, court referred, placed in locked facilities, and transferred to adult criminal courts. In fact, African American youth are 6 times more likely than White youth to experience a secure facility placement. Standardized risk assessments have been used, in part, to reduce these biased placement outcomes. The purpose of this article is to determine if DMC impacts secure detention placement even when a standardized risk assessment is used to determine youths\u27 risks and needs in 1 Midwest county\u27s juvenile court population over a 17-month time frame. Multivariate binary logistic regression results indicated and confirmed that African American youth were 2 times more likely to receive secure detention center placement than non-African American youth even when a standardized risk assessment was used. Practical applications and recommendations are set forth

Predicting Secure Detention Placement for African-American Juvenile Offenders: Addressing the Disproportionate Minority Confinement Problem

Disproportionate minority contact and confinement (DMC) are significant problems within the juvenile justice system in the United States. Minority youth are more often arrested, court referred, placed in locked facilities, and transferred to adult criminal courts. In fact, African American youth are 6 times more likely than White youth to experience a secure facility placement. Standardized risk assessments have been used, in part, to reduce these biased placement outcomes. The purpose of this article is to determine if DMC impacts secure detention placement even when a standardized risk assessment is used to determine youths\u27 risks and needs in 1 Midwest county\u27s juvenile court population over a 17-month time frame. Multivariate binary logistic regression results indicated and confirmed that African American youth were 2 times more likely to receive secure detention center placement than non-African American youth even when a standardized risk assessment was used. Practical applications and recommendations are set forth

Tunable morphological properties of silver enriched platinum allied nanoparticles and their catalysed reduction of p-nitrophenol

A robust polymer based and polyol mediated procedure to synthesize nanobimetallic particles has been modified to produce core–shell and alloy Ag/Pt nanoparticles with tunable properties. Novel three-dimensional (3D) quasi nanocubes entangled in nanowebs were produced by rapid solution phase transformation with hot addition of absolute ethanol. The optical characterization showed extinction of plasmon resonance band occurring with incremental feeding ratio of Pt source in all cases. Transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) images revealed that the shape, size and size distribution of asprepared silver platinum nanoparticles depended on the stabilizer or capping agent, mole ratio of metal ion sources, temperature and time of reaction. Meanwhile, catalytic activity was highest in the reduction of p-nitrophenol in the presence of polyvinylpyrrolidone/diethylene glycol stabilized Ag/Pt nanoparticles

Parental Divorce: A Protection from Later Delinquency for Maltreated Children

Family structure and maltreatment (abuse and neglect) have been identified as predictors of youth delinquency, although the relationship is not clear. This article furthers this research by studying a sample of maltreated children (n = 250) in one Midwest county, and through a multiple regression analysis of many risk factors, the study identified only one significant delinquency variable that made delinquency less likely—children who experience parental divorce. Some established risk factors were surprisingly found not to be predictive of later delinquency: minority race, one-parent families, youth substance abuse, recurrent maltreatment, and youth behind in academic grade level. Implications for the family studies and juvenile justice fields are set fort

Denial in Alcohol and Other Drug Use Disorders: A Critique of Theory.

Despite the centrality of the construct in the field of alcohol and other drug (AOD) addiction, denial remains poorly conceptualized. One reason for this narrow conceptualization is the recent unilateral devotion to the Transtheoretical Model (TTM). In an effort to demonstrate denial’s theoretical complexity, the TTM and five additional intuitively appealing theories of denial will be summarized.The strengths and weaknesses of each theory and possible treatment implications based on each theory will also be presented. The article concludes with a recommendation for future research to evaluate multiple theories of denial using consistent and rigorous research methodology in order to develop a comprehensive theory of denial. This will promote evolution of the deductive research process, and eventually lead to the development of empirically generated interventions which address the complex nature and etiology of denial