Soluble poly-3-alkylpyrrole polymers on films and fabrics

Conductive textiles with specific properties can be produced by the chemical polymerisation of a range of 3-alkylpyrroles in the presence of textiles. The morphologies of these coatings are altered from the traditional conductive coatings. Comparison using a SEM reveals substantial differences.<br /

In silico activation of dinitrogen with a light atom molecule

The N[triple bond, length as m-dash]N triple bond can be cleaved in silico with a light atom molecule containing only the earth abundant elements C, H, Si, and P. Extensive density functional theory (DFT) computations on various classes of peri-substituted scaffolds containing Lewis acidic and basic sites in the framework of frustrated Lewis pairs (FLP) indicate that the presence of two silyl cations and two P atoms in a flexible but not too flexible arrangement is essential for energy efficient N2-activation. The non-bonding lone-pair electrons of the P atoms thereby serve as donors towards N2, whereas the lone-pairs of N2 donate into the silyl cations. Newly formed lone-pair basins in the N2-adducts balance surplus charge. Thereby, the N–N bond distance is increased by astonishing 0.3 Å, from 1.1 Å in N2 gas to 1.4 Å in the adduct, which makes this bond prone to subsequent addition of hydride ions and protonation, forming two secondary amine sites in the process and eventually breaking the N[triple bond, length as m-dash]N triple bond. Potential formation of dead-end states, in which the dications (“active states”) aversively form a Lewis acid (LA)–Lewis base (LB) bond, or in which the LA and LB sites are too far away from each other to be able to capture N2, are problematic but might be circumvented by proper choice of spacer molecules, such as acenaphthalene or biphenylene, and the ligands attached to the LA and LB atoms, such as phenyl or mesityl, and by purging the reaction solutions with gaseous N2 in the initial reaction steps. Charge redistributions via N2-activation and splitting were monitored by a variety of real-space bonding indicators (RSBIs) derived from the calculated electron and electron pair densities, which provided valuable insight into the bonding situation within the different reaction steps

In silico capture and activation of methane with light atom molecules

Methane (CH4) can be captured in silico with a light atom molecule containing only C, H, Si, O, and B atoms, respectively. A tripodal peri-substituted ligand system was employed, namely, [(5-Ph2B-xan-4-)3Si]H (1, xan = xanthene), which after hydride abstraction (1+) carries four Lewis acidic sites within the cationic cage structure. In a previous study, this system was shown to be able to capture noble gas atoms He–Kr (Mebs & Beckmann 2022). In the corresponding methane complex, 1+CH4, a polarized Si+⋯CH4 contact of 2.289 Å as well as series of (H3)CH⋯O/CPh hydrogen bonds enforce spatial CH4 fixation (the molecule obeys C3-symmetry) and slight activation. A trigonal-pyramidal Si–CHeq3–Hax local geometry is thereby approached with Hax–C–Heq angles decreased to 103.7°. All attempts to replace the Lews acidic –BPh2 fragments in 1 with basic –PR2 (R = Ph, tBu) fragments indeed increased intra-molecular hydrogen bonding between host molecule and CH4, and thus caused stronger activation of the latter, however ultimately resulted in the formation of energetically favorable quenched structures with short P–Si contacts, making CH4 binding hard to achieve. The electronic situation of two hypothetic methane complexes, 1+CH4 and [(5-tBu2P-xan-4-)3SiCH4]+ (2+CH4), was determined by a set of calculated real-space bonding indicators (RSBIs) including the Atoms-In-Molecules (AIM), non-covalent interactions index (NCI), and electron localizability indicator (ELI-D) methods, highlighting crucial differences in the level of activation. The proposed ligand systems serve as blueprints for a more general structural design with adjustable trigonal ligand systems in which central atom, spacer fragment, and functional peri-partner can be varied to facilitate different chemical tasks

In silico capture of noble gas atoms with a light atom molecule

Noble gas atoms (Ng = He, Ne, Ar, and Kr) can be captured in silico with a light atom molecule containing only C, H, Si, O, and B atoms. Extensive density functional theory (DFT) calculations on series of peri-substituted scaffolds indicate that confined spaces (voids) capable to energy efficiently encapsulate and bind Ng atoms are accessible by design of a tripodal peri-substituted ligand, namely, [(5-Ph2B-xan-4-)3Si]H (xan = xanthene) comprising (after hydride abstraction) four Lewis acidic sites within the cationic structure [(5-Ph2B-xan-4-)3Si]+. The host (ligand system) thereby provides an adoptive environment for the guest (Ng atom) to accommodate for its particular size. Whereas considerable chemical interactions are detectable between the ligand system and the heavier Ng atoms Kr and Ar in the host guest complex [(5-Ph2B-xan-4-)3Si·Ng]+, the lighter Ng atoms Ne and He are rather tolerated by the ligand system instead of being chemically bound to it, nicely highlighting the gradual onset of (weak) chemical bonding along the series He to Kr. A variety of real-space bonding indicators (RSBIs) derived from the calculated electron and pair densities provides valuable insight to the situation of an “isolated atom in a molecule” in case of He, uncovering its size and shape, whereas minute charge rearrangements caused by polarization of the outer electron shell of the larger Ng atoms results in formation of polarized interactions for Ar and Kr with non-negligible covalent bond contributions for Kr. The present study shows that noble gas atoms can be trapped by small light-atom molecules without the forceful conditions necessary using cage structures such as fullerenes, boranes and related compounds or by using super-electrophilic sites like [B12(CN)11]− if the chelating effect of several Lewis acidic sites within one molecule is employed

In Silico Activation of CO2, NO2, and SO2 with Light Atom Molecules and Stepwise Conversion of CO2 into Methanol and Water

CO2, NO2, and SO2 can be activated in silico with tailor-made light atom tripodal ligand systems carrying particular numbers of Lewis acidic and basic sites in specific relative orientations. In the calculated EO2-adducts (E=C, N, S), considerable E−O bond elongations of 0.1–0.3 Å, decreasing the E=O double bond character, and O−E−O angle alterations, approaching tetrahedral geometry, activate the donor acceptor complexes towards reduction with BH4−. The lone pairs of the P atoms thereby serve as donors towards the central element, C, N, or S, whereas the electron deficient B atoms serve as acceptors. The charge redistribution within the EO2 complex was monitored by a variety of DFT-derived real-space bonding indicators (RSBIs) including bond topologies, non-covalent contact patches, and electron pair basins. For one CO2-complex, the reduction towards methanol and water was conducted via stepwise addition of H− and H+. The most critical steps are the initial CO2 uptake due to potential quenching of the ligand systems in their active state, increasing the kinetic barrier, and the release of methanol and water from the ligand system due to potential ligand poisoning. Unbeneficial side reactions in the stepwise reduction and protonation have to be considered

The Bis(ferrocenyl)phosphenium Ion Revisited

The bis(ferrocenyl)phosphenium ion, [Fc2P]+, reported by Cowley et al. (J. Am. Chem. Soc. 1981, 103, 714–715), was the only claimed donor‐free divalent phosphenium ion. Our examination of the molecular and electronic structure reveals that [Fc2P]+ possesses significant intramolecular Fe⋅⋅⋅P contacts, which are predominantly electrostatic and moderate the Lewis acidity. Nonetheless, [Fc2P]+ undergoes complex formation with the Lewis bases PPh3 and IPr to give the donor–acceptor complexes [Fc2P(PPh3)]+ and [Fc2P(IPr)]+ (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazole‐2‐ylidene)

From procrastination to engagement? An experimental exploration of the effects of an adaptive virtual assistant on self-regulation in online learning

Compared to traditional classroom learning, success in online learning tends to depend more on the learner’s skill to self-regulate. Self-regulation is a complex meta-cognitive skill set that can be acquired. This study explores the effectiveness of a virtual learning assistant in terms of (a) developmental, (b) general compensatory, and (c) differential compensatory effects on learners’ self-regulatory skills in a sample of N = 157 online learners using an experimental intervention-control group design. Methods employed include behavioural trace data as well as self-reporting measures. Participants provided demographic information and responded to a 24-item self-regulation questionnaire and a 20-item personality trait questionnaire. Results indicate that the adaptive assistance did not lead to substantial developmental shifts as captured in learners’ perceived levels of self-regulation. However, various patterns of behavioural changes emerged in response to the intervention. This suggests that the virtual learning assistant has the potential to help online learners effectively compensate for deficits (in contrast to developmental shifts) in self-regulatory skills that might not yet have been developed

Dynamic testing of language learning aptitude: an exploratory proof of concept study

This paper provides an example for how online technology can be utilised to increase efficiency and validity of assessment procedures beyond simple computerization of testing. We report the first steps of the development of an online assessment procedure for the measurement of language learning aptitude that is based on the concept of dynamic testing. Online adaptive dynamic tests provide learning opportunities in the test situation, allowing test takers demonstrate their ability to benefit from feedback. Test performance shown in such test procedures has been demonstrated to be more useful in predicting future learning and to represent a more valid indication of test takers’ learning potential. The newly developed online assessment procedure aims at measuring young learner’s ability to improve performance based on inductive reasoning across lexical, morphological and syntactic rules of an artificial language using pictorial stimuli. The test was administered on ten mainland Chinese children aged between 9 and 13. The tentative analysis indicates that the newly developed test is feasible and has the potential to be a useful diagnostic tool for measuring language learning aptitude. We report and discuss insights gained and outline how these will be utilised for the further refinement of this online assessment tool

2-(2-Pyridylamino)Pyridinium2-(2-Pyridylamino)pyridinium chloride phosphorous acid: one-dimensional hydrogen-bonded and [π]-[π] stacked supramolecular chains

In the crystal structure of the title compound, C10H10N3+&middot;Cl-&middot;[P(O)(OH)2H], the chloride ion and phosphorous acid form a one-dimensional hydrogen-bonded chain, while the 2-(2-pyridylamino)pyridinium cations form a second chain through [&pi;]-[&pi;] stacking. The two parallel chains are connected via a PO...H-N hydrogen bond and a weak pyridinium-to-chloride interaction.<br /

Synthesis and structure of pentamethylcyclopentadienyltin(II) tetraphenylborate

The title compound (Cp*Sn)BPh 4 was obtained by the metathesis reaction of Cp*SnCl with NaBPh4and characterized by single crystal X-ray diffraction as well as solution and solid-state 119Sn nuclear magnetic resonance (NMR) spectroscopy. The coordination modes are best described as (&nu; 5-C5Me 5)Sn(&mu;-&nu;6-Ph) 2BPh2