Chemistry

In this study, the corrosion behavior of pure aluminum in methyl esters with different degrees of unsaturation and chain lengths, as found in biodiesel, was investigated using electrochemical techniques. The methyl esters evaluated included methyl acrylate (C₄H₆O₂) and methyl linoleate (C₁₉H₃₄O₂), which were added to methyl propionate (C₄H₈O₂) and methyl oleate (C₁₉H₃₆O₂), respectively. The electrochemical techniques employed were electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN), complemented by detailed scanning electron microscopy (SEM) analyses. The results indicated that both the corrosion rate and the susceptibility to localized corrosion, such as pitting, increased with higher degrees of unsaturation and longer alkyl chain lengths. The corrosion process remained under charge transfer control and was not directly influenced by these factors. However, the charge transfer resistance decreased with increasing unsaturation and chain length, consistent with the observed increase in corrosion rate.

The inadequate biosafety of MRI contrast agents (CAs) remains a challenging issue. Both increasing the magnetic relaxivity of CAs and targeting them through conjugation with folates are promising approaches to addressing this issue. Silica nanoparticles (SNs) with Mn²⁺ ions specifically localized in the outer layer were selected as the target for further surface modification for the covalent attachment of folates. It was shown that when Mn-containing SNs are conjugated with folates via preliminary amino modification of the surface silanol groups, the folate-conjugated SNs suffer from colloidal instability. Thus, precoating Mn-containing SNs with unfolded BSA exposes surface amino groups that successfully conjugate with folates without loss of colloidal stability. Partial washout of surface-localized Mn²⁺ follows folate conjugation of Mn-containing SNs, although residual Mn²⁺ ions provide r₁₍₂₎ relaxivities of 62.1 (160.4) mM⁻¹s⁻¹ at 0.47 T.

Visible-light photocatalysis enables the integration of classical electrophile/nucleophile chemistry with radical species (free radicals, radical cations, and radical anions) and metallocomplexes, significantly expanding the scope of organic transformations. Substrates capable of generating radicals via single-electron transfer (SET) are therefore of high value in this field. Among conventional radical precursors, organic peroxides occupy a distinctive position due to their unique reactivity. They can generate both oxygen-centered and carbon-centered radicals through either oxidative or reductive SET pathways. Furthermore, organic peroxides can act as radical precursors, nucleophiles, and oxidants. The review emphasizes the advancements of visible-light-mediated reactions utilizing the broad potential of organic peroxides for constructing various chemical bonds.