Ligand Exchange Reaction between Ferrocene and Multiwalled Carbon Nanotubes: A Contemporary Approach.

Ligand exchange reaction (LER) between carbon nanoparticles and ferrocene (Cp2Fe) was conducted several times, but there was no convincing evidence of half-sandwich CpFe+ coordination to multiwalled carbon nanotubes (MWCNT). In this study, MWCNT is modified by LER with ferrocene using AlCl3/Al as a catalytic system. The modified MWCNT (Fc-MWCNT) are investigated for better understanding of the processes taking place on the surface of MWCNT using different spectroscopic and electrochemical methods. The formation of the Fe-C covalent bond between CpFe+ and MWCNT is confirmed by changes in the Raman spectrum of Fc-MWCNT compared to pristine MWCNT. The densest structure of Fc-MWCNT is investigated by transmission electronic microscopy. According to density-functional theory calculations of the model interaction between Fe and coronene, the Fe-C bond length is 2.1687-2.1855 Å. X-ray photoelectron spectroscopy also confirms the coordination of the Fe atom to MWCNT by analysis of oxidation states of Fe 2p and deconvolution of C 1s. Utilization of cyclic voltammetry corroborated MWCNT modification via LER. These data are important for both theoretical and practical applications due to increased interest in LER-modified compounds in different areas including thermoelectric devices, sensors, and its potential application in the field of molecular machine construction.

Iridium(III)-Incorporating Self-Healing Polysiloxanes as Materials for Light-Emitting Oxygen Sensors.

Polymer-metal complexes (PMCs) based on poly(2,2'-bipyridine-4,4'-dicarboxamide-co-polydimethylsiloxanes) with cyclometalated di(2-phenylpyridinato-C2,N')iridium(III) fragments and cross-linked by Zn2+ (Zn[Ir]-BipyPDMSs) or Ir3+ (Ir[Ir]-BipyPDMSs) represent flexible, stretchable, phosphorescent, and self-healing molecular oxygen sensors. PMCs provide strong phosphorescence at λem = 595-605 nm. Zn[Ir]-BipyPDMS with PDMS chain length of Mn = 5000 has the highest quantum yield of 9.3% and is a molecular oxygen sensor at different O2 concentrations (0-100 vol%) compared to Ir[Ir]-BipyPDMSs. A Stern-Volmer constant is determined for Zn[Ir]-BipyPDMS as KSV = 0.014%-1, which is similar to the reported oxygen-sensitive iridium(III) complexes. All synthesized PMCs exhibit high elongation at break (up to 1100%) and self-healing efficiency (up to 99%).

Gamma-linolenic Acid from Fifty-seven Ribes Species and Cultivars.

γ-linolenic acid (GLA, 18:3n-6) is a bioactive fatty acid (FA) that exerts several healthy actions; however, its occurrence is restricted to a few oils. The goal of this study was to detect GLA-rich Ribes species and cultivars (cv), and to achieve this the seeds of 7 Ribes taxa and 50 Ribes cv were surveyed for FA profiles. The highest GLA percentages were found in R. nigrum cv 'Plotnokistnaya', 'Volshebnica', 'Atlant' and 'Nara' (22.6, 22.1, 20.9, and 20.0% of total FA, respectively) and also in R. komarovii (19.6%) and R. nigrum var. sibiricum (18.3%). Stearidonic acid (SDA, 18:4n-3) had the highest values in both R. rubrum 'Konstantinovskaya' and R. niveum 'Smolyaninovskaya' (4.8%). GLA content ranged from 0.4 in some R. rubrum cv and R. niveum 'Smolyaninovskaya' to 3.5 g/100 g seeds in R. nigrum 'Plotnokistnaya'. Principal component analysis (PCA) was performed using PUFA profiles, which allowed grouping Ribes sections as well as black currant cv derived from different pedigree within the section Coreosma. All taxa and cv checked here are valuable by-product sources, given the high GLA percentages contained in their seed oils. Such cv could be used for healthy oils production, as well as for breeding to obtain new cv with improved GLA concentrations.

Platinum macrocatalyst for heterogeneous Si-O dehydrocoupling.

A platinum polymer catalyst (Pt-PDMS) was synthesized by immobilization of a platinum catalytic complex in a polysiloxane chain using an azide-alkyne CuAAC cycloaddition. Insoluble Pt-PDMS can be used as an effective heterogeneous macrocatalyst for Si-O dehydrocoupling. Pt-PDMS is easy to recover, purify, and reuse again for heterogeneous catalysis.