35Cl nuclear quadrupole resonance (NQR) and Density functional theory (DFT) computations are combined to characterize chlorine environments in polyvinyl chloride (PVC) and detect structural defects. Calculations validated against reference data enable to classify two main groups of signals: terminal and internal chlorines, the former having ∼1 MHz higher ν. We also predict distinct 35Cl NQR signatures for chlorine vacancies and additional vicinal/geminal chlorines, resulting in an increased ν. Using this methodology, two types of PVC samples are analyzed: commercial high-MW and low-MW PVC. Both show numerous Cl environments associated with both terminal and internal Cl, as well as additional features indicating the presence of Cl defects. Analysis of a partially dechlorinated PVC reveals that dechlorination primarily occurs at the terminal positions, while multichlorinated sites are less reactive and remain mostly untouched. This combined computational–experimental approach demonstrates that 35Cl NQR can sensitively distinguish chlorine sites in PVC, enabling the direct detection of defects relevant to stability, degradation, and recycling strategies.

Photoexcitation of organic diradicals bridged by inverted singlet‒triplet systems (InveST) activates exchange that polarizes the radicals into a triplet state. Using model Hamiltonians and multirefere...

Methylammonium lead chloride perovskite (MAPbCl3), with its wide bandgap of ∼3 eV, exhibits unique advantages for near-UV to UV optoelectronic devices. However, the fast crystallization kinetics and s...

Accurate interaction energies can be obtained using high-level quantum chemical methods such as DLPNO–CCSD(T) and its HFLD variant in ORCA. The local energy decomposition (LED) scheme helps interpret ...

We present a pentadentate bispidine iron complex with a guanidine pendant group at one of the pyridine donors (bispidine = 3,7-diazabicyclo[3.3.1]nonane), whose iron(II) precursor can be oxidized with iodosylbenzene in strictly water- and oxygen-free solution to an iron(III) species that is a competent catalyst for oxygen atom transfer (OAT) to thioanisole. Time-dependent UV–vis–NIR spectroscopy and ESI and tandem mass spectrometry, supported by EPR and Mössbauer spectroscopy and the investigation of the OAT activity, lead to the conclusion that the active species is an iron(III)-peroxido complex and that its formation is initiated by an intramolecular C–H abstraction (HAA) at the guanidinyl substituent, followed by OH rebound to produce an iron(II) intermediate with a hydroxylated guanidinyl substituent. This is reoxidized to the corresponding iron(IV)-oxido intermediate, where the FeIV=O and ligand–OH groups are well preorganized for an intramolecular O–O bond formation. An outer-sphere oxidation then produces the iron(III)-peroxido complex, which relatively efficiently sulfoxidizes thioanisole. A detailed DFT-based computational study supports the experimental observations and indicates that the initial HAA is rate determining; that is, O–O bond formation is a very efficient process. The effectiveness of the initial HAA, that of the OH rebound and specifically that of the O–O bond formation, are shown to be due to the well preorganized coordination sphere of the iron-bispidine active species.

This technology for rapid, non-invasive toxicology screening could allow for earlier intervention for patients at risk for drug overdose or in need of substance use treatment.

Plasma protein binding is an important determinant in the clinical success of oligonucleotide-based drugs. Optimal protein binding of the oligonucleotide is critical to its tissue distribution and ret...

Nearly a century of road salt use in the snowbelt region of North America has led to substantial increases in salinity levels in freshwater habitats. Salt pollution in lakes and rivers is well charact...