Heterogeneous Electrocatalytic Oxygen Evolution Reaction by a Sol-Gel Electrode with Entrapped Na3 [Ru2 (µ-CO3 )4 ]: The Effect of NaHCO3.

The Na3 [Ru2 (µ-CO3 )4 ] complex is acting as a water oxidation catalyst in a homogeneous system. Due to the significance of heterogeneous systems and the effect of bicarbonate on the kinetic, we studied the bicarbonate effect on the heterogeneous electrocatalyst by entrapping the Na3 [Ru2 (µ-CO3 )4 ] complex in a sol-gel matrix. We have developed two types of sol-gel electrodes, which differ by the precursor, and are demonstrating their stability over a minimum of 200 electrochemical cycles. The pH increases affected the currents and kcat for both types of electrodes, and their hydrophobicity, which was obtained from the precursor type, influenced the electrocatalytic process rate. The results indicate that NaHCO3 has an important role in the catalytic activity of the presented heterogeneous systems; without NaHCO3 , the diffusing species is probably OH- , which undergoes diffusion via the Grotthuss mechanism. To the best of our knowledge, this is the first study to present a simple and fast one-step entrapment process for the Na3 [Ru2 (µ-CO3 )4 ] complex by the sol-gel method under standard laboratory conditions. The results contribute to optimizing the WSP, ultimately helping expand the usage of hydrogen as a green and more readily available energy source.

Regioselective chromatic orthogonality with light-activated metathesis catalysts.

The ability to selectively guide consecutive chemical processes towards a preferred pathway by using light of different frequencies is an appealing concept. Herein we describe the coupling of two photochemical reactions, one the photoisomerization and consequent activation of a sulfur-chelated latent olefin-metathesis catalyst at 350 nm, and the other the photocleavage of a silyl protecting group at 254 nm. Depending on the steric stress exerted by a photoremovable neighboring chemical substituent, we demonstrate the selective formation of either five- or six-membered-ring frameworks by light-triggered ring-closing metathesis. The orthogonality of these light-induced reactions allows the initiation of these processes independently and in interchangeable order, according to the wavelength of light used to promote them.

Advanced sol-gel process for efficient heterogeneous ring-closing metathesis.

Olefin metathesis, a powerful synthetic method with numerous practical applications, can be improved by developing heterogeneous catalysts that can be recycled. In this study, a single-stage process for the entrapment of ruthenium-based catalysts was developed by the sol-gel process. System effectiveness was quantified by measuring the conversion of the ring-closing metathesis reaction of the substrate diethyl diallylmalonate and the leakage of the catalysts from the matrix. The results indicate that the nature of the precursor affects pore size and catalyst activity. Moreover, matrices prepared with tetraethoxysilane at an alkaline pH exhibit a better reaction rate than in the homogenous system under certain reaction conditions. To the best of our knowledge, this is the first study to present a one-step process that is simpler and faster than the methods reported in the literature for catalyst entrapment by the sol-gel process under standard conditions.

Studies on electronic effects in O-, N- and S-chelated ruthenium olefin-metathesis catalysts.

A short overview on the structural design of the Hoveyda-Grubbs-type ruthenium initiators chelated through oxygen, nitrogen or sulfur atoms is presented. Our aim was to compare and contrast O-, N- and S-chelated ruthenium complexes to better understand the impact of electron-withdrawing and -donating substituents on the geometry and activity of the ruthenium complexes and to gain further insight into the trans-cis isomerisation process of the S-chelated complexes. To evaluate the different effects of chelating heteroatoms and to probe electronic effects on sulfur- and nitrogen-chelated latent catalysts, we synthesised a series of novel complexes. These catalysts were compared against two well-known oxygen-chelated initiators and a sulfoxide-chelated complex. The structures of the new complexes have been determined by single-crystal X-ray diffraction and analysed to search for correlations between the structural features and activity. The replacement of the oxygen-chelating atom by a sulfur or nitrogen atom resulted in catalysts that were inert at room temperature for typical ring-closing metathesis (RCM) and cross-metathesis reactions and showed catalytic activity only at higher temperatures. Furthermore, one nitrogen-chelated initiator demonstrated thermo-switchable behaviour in RCM reactions, similar to its sulfur-chelated counterparts.

A Qualitative Research for Defining Meaningful Attributes for the Treatment of Inflammatory Bowel Disease from the Patient Perspective.

INTRODUCTION: Crohn's disease (CD) and ulcerative colitis (UC) are chronic, inflammatory bowel diseases (IBD). Each class and type of medication available for the treatment of IBD has distinct characteristics and long-term effects that a patient may consider. We present the results of qualitative research that aimed to develop a descriptive framework that outlines the most relevant disease and/or treatment attributes for IBD treatment decisions and focuses on the patient perspective. METHODS: This research employed a three-step approach: a literature review to identify a broad list of attributes, a focus group meeting including patients and clinicians to assess the relevance of the attributes, and two rounds of voting to name and define each attribute. The literature review was used to develop the initial list of attributes. Although the same attributes were defined for both UC and CD, the relative importance of each attribute to UC or CD was considered. The list of attributes was discussed and evaluated in the focus group meeting, which included eight patient representatives and nine gastroenterologists. Using feedback elicited from the focus group meeting, the research team developed a draft of the descriptive framework that grouped the attributes into domain subsets. All members of the focus group participated in two subsequent rounds of structured, online voting, which was used to refine the wording to name and define each attribute. Additionally, participants ranked all the attributes included in the descriptive framework to suggest which attributes were less relevant and could be omitted. RESULTS: Among 574 publications retrieved from the databases and registries, we identified 32 eligible publications, and an initial list of attributes was developed. This list was refined during the focus group meeting, resulting in a draft descriptive framework of attributes within subsets of domains. The final descriptive framework was developed based on structured rounds of online voting to further refine attribute names and definitions. In the final descriptive framework, a total of ten attributes were identified: abdominal pain, other disease-related pain, bowel urgency, fatigue, risk of cancer and serious infections within the next 10 years, risk of mild to moderate complications, aesthetic complications related to treatment, emotional status, sexual life, and social life and relationships. These attributes were distributed across three domains: efficacy, complications and risk, and health-related quality of life. CONCLUSIONS: Through the identification of the ten most relevant attributes that influence patient decision making for IBD treatments, we developed a descriptive framework that should be considered by physicians when discussing IBD treatment options with their patients. The results of our qualitative research may also be helpful for the development of future IBD clinical studies and quantitative research.

Predicting the cis-trans dichloro configuration of group 15-16 chelated ruthenium olefin metathesis complexes: a DFT and experimental study.

Gradient-corrected (BP86) and hybrid (M06-L) density functional calculations were used to study the relative stability of cis and trans-dichloro X-chelated benzylidene ruthenium complexes (X = O, S, Se, N, P). Calculations in the gas phase differed from experimental results, predicting the trans-dichloro configuration as being more stable in every case. The addition of Poisson-Boltzmann (PBF) continuum approximation (dichloromethane) corrected the disagreement and afforded energies consistent with experimental results. Novel N, Se, and P chelated ruthenium olefin metathesis complexes were synthesized to evaluate calculation predictions. These findings reinforce the importance of including solvent corrections in DFT calculations of ruthenium metathesis catalysts and predict that stronger sigma donors as chelating atoms tend to electronically promote the unusual and less active cis-dichloro configuration.