Search

The Faraday Discussion 'From optical to THz control of materials' was held in London, UK, and online on the 23rd, 24th, and 25th May 2022. The meeting brought together established and early-career scientists, postgraduate students, scientific editors, and industrial researchers in the field of spectroscopy and materials science from over ten different countries interested in exploring the physical properties of materials at ultrafast timescales driven by optical and THz excitations. This conference report provides highlights of this meeting and we give summaries of the presentations including the introductory lecture, all the papers discussed, and the concluding remarks. [ABSTRACT FROM AUTHOR]

In this work we report a new PbII coordination polymer [Pb3L2(N3)4] n , which was obtained from Pb(N3)2 and 1-(pyridin-2-yl)ethylidenepicolinohydrazide (HL). The complex exhibits a 1D polymeric chain, constructed from the {[Pb3(N3)4]2+}n backbone, decorated with deprotonated organic L− ligands. The latter ligands are pentadentate and link two metal cations. The PbII ions were found to be in a N5O or N5O2 coordination environment, formed by covalent bonds. The azide ligands either bind four metals in a μ4-1,1,3,3 coordination mode or are coordinated to metal centers as terminal ligands. All the metal centers exhibit a hemidirected coordination geometry with a pronounced coordination gap, which allows the close approach of an additional nitrogen atom arising from an adjacent terminal azide ligand. A simplified underlying network of [Pb3L2(N3)4] n , without considering Pb⋯N tetrel bonds, exhibits the tetranodal 3,4,4,4-connected chain topology, while considering all Pb⋯N tetrel bonds, the binodal 4,5-connected chain topology was shown. The crystal packing of [Pb3L2(N3)4] n is reinforced by intermolecular π⋯π stacking interactions, formed by PbII-based five-membered chelate metallocycles and pyridine rings. In-depth bonding analysis using ETS-NOCV, IQA and NCI methods demonstrates that although the azide anions experience significant steric crowding due to repulsive azide–azide interactions, they are engaged in strong attractive, Coulomb dominated, dative-covalent Pb–N and tetrel-type Pb⋯N connections, which are further augmented by weak exchange–correlation driven C–H⋯N hydrogen bonds as well as London dispersion forces due to metallocycle units. The diffuse reflectance spectrum of [Pb3L2(N3)4] n revealed a broad band with two maxima in the UV region, corresponding to intraligand transitions, and an intense shoulder in the visible region, corresponding to metal-to-ligand charge-transfer. The latter shoulder explains the observed yellow colour of the complex. [ABSTRACT FROM AUTHOR]

Three cadmium(II) coordination polymers, namely {[Cd(HLI)(NO3)2]·0.5MeOH}n (1), {[Cd(HLII)(NO3)2]·EtOH}n (2), and [Cd2(LII)2(NO3)2]n (3), have been self-assembled from Cd(NO3)2 and N,N′,O-pincer-type isonicotinoylhydrazone-based ditopic ligands (HLI = N′-(pyridin-2-ylmethylene)isonicotinohydrazide and HLII = N′-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide) and have been characterized experimentally and by DFT computations. In compounds 1 and 2, the corresponding ligand is coordinated to the metal center in the keto form and acted as a tetradentate chelating–bridging agent in which the nitrogen atom of the 4-pyridine ring is coordinated to the cadmium center of the neighboring unit, yielding 1D zig-zag coordination polymers. In compound 3, the ligand was singly-deprotonated and is coordinated in the enolic form with the nitrate ion further acted as a bridging agent, yielding a 2D network. It is revealed by the extended transition state natural orbital for chemical valence (ETS-NOCV) charge and energy decomposition scheme that typical hydrogen bonds O–H⋯O and N–H⋯O, which constitute the networks of 1 and 2, though dominated by a classic Coulomb term, are characterized by an equally important London dispersion constituent due to extra π⋯π and C–H⋯X contacts (X = O, H–C, H–N). The architecture of 3 is due to ionic and dative-covalent Cd–X (X = N, O) bonds as well as London dispersion-driven homopolar dihydrogen C–H⋯H–C and C–H⋯O interactions. NOCV-based representation allowed us to determine that hydrogen bonds O–H⋯O are twice weaker than the corresponding N–H⋯O in the networks of 1 and 2. [ABSTRACT FROM AUTHOR]

We report the design, structural, spectroscopic and computational characterization of the two new quasiaromatic Möbius chelate coordination compounds fabricated from Cd(NO3)2·4H2O and a bulky helical organic ligand derived from benzildihydrazone and 2-pyridinecarboxaldehyde (L) in the presence and absence of two equivalents of NaNO2, namely [Cd(NO2)x(NO3)2-x(L)]·2MeOH (1·2MeOH) and [Cd(NO3)2(L)]·MeOH (2·MeOH). The former complex was found to extensively lose one of the lattice solvent molecules of methanol under ambient conditions upon isolation from the mother liquor. Therefore, the crystal structure of 1·2MeOH was obtained at 100 K, namely [Cd(NO2)1.67(NO3)0.33(L)]·2MeOH ((1-100 K)·2MeOH), and at 296 K, namely [Cd(NO2)1.57(NO3)0.43(L)]·2MeOH ((1-296 K)·MeOH). In all the structures, anions exhibit a chelate 2-O,O-mode. It was found that the reported Cd-NO2 and Cd-NO3 connections are largely ionic in nature, followed by dative covalent charge delocalization and the London dispersion constituents. The electron density of delocalized bonds (EDDB) function and the extended transition state (ETS) energy decomposition method combined with the natural orbitals for chemical valence (ETS-NOCV) have shown sizeable p-delocalizations within the twisted ligand L suggesting quasi-aromatic Möbius features of the Cd-L chelate. Finally, the optical properties of (1-296 K)·MeOH and 2·MeOH have been investigated by diffuse reflectance spectroscopy. [ABSTRACT FROM AUTHOR]

The perfluorinated alkoxy silanes {(F3C)3CO}3SiH (1) and {(F5C6)3CO}2Si(Cl)H (2) were prepared and fully characterized. Despite the high calculated Brønsted acidities, all attempts to deprotonate 1 and 2 to give the conjugate silanide ions failed due to the exceptionally short and strong Si–H bonds. In the solid state, the Si–H units are not involved in any intermolecular interactions, but instead the crystal packing consists of exceptionally short and strong F⋯F interactions. The cohesive energies are entirely comprised of London dispersion interactions, similarly as in the crystal structures of noble gases. [ABSTRACT FROM AUTHOR]

In this article, we present a summary of the Faraday Discussion that took place on September 21–23, 2022 in London, UK. The primary goal of this event was to promote and discuss the recent developments in the field of nanoalloys. Here we briefly outline each scientific session as well as other conference events. [ABSTRACT FROM AUTHOR]

The 300th Faraday discussion on hot electron processes in plasmonics and catalysis brought together a wide spectrum of delegates from across the globe. Scientists from across multiple disciplines, with a broad spectrum of experience and expertise, joined together in hope of identifying and answering the latest problems within the ever growing hot electron science community. In this paper we present a brief overview of the themes and topics presented at this meeting, highlighting the major findings of each presentation. [ABSTRACT FROM AUTHOR]

In this work, we report extensive experimental and theoretical investigations on a new series of PbII coordination polymers exhibiting extended supramolecular architectures, namely [Pb2(LI)(NCS)4]n (1), [Pb(HLII)I2]n (2), [Pb(LIII)I]n (3) and [Pb(HLIV)(NO3)2]n·nMeOH (4), which were self-assembled from different PbII salts and various pyridine-hydrazine based linkers, namely 1,2-bis(pyridin-3-ylmethylene)hydrazine (LI), (pyridin-4-ylmethylene)isonicotinohydrazide (HLII), 1-(pyridin-2-yl)ethylidenenicotinohydrazide (HLIII) and phenyl(pyridin-2-yl)methylenenicotinohydrazide (HLIV), respectively. It is recognized that the origin of self-assembling is fundamentally rooted in a dual donor (6s2/6p0 hybridized lone electron pair) and electrophilic behaviour of PbII. This allows production of extended topologies from a 1D polymeric chain in 4 through a 2D layer in 2 to the 3D frameworks in 1 and 3, predominantly due to the cooperative action of both covalent and non-covalent tetrel interactions of the overall type Pb–X (X = O, N, S, I). Counterintuitively, the latter, seemingly weak interactions, have appeared to be even stronger than the typical covalent bonds due to the presence of a bunch of supportive London dispersion dominated contacts: π⋯π, Lp⋯π, C–H⋯O, C–H⋯I, C–H⋯H–C as well as more typical mainly electrostatically driven N–H⋯O or N/O–H⋯O hydrogen bonds. It is revealed that the constituting generally strong tetrel type Pb–X (X = O, N, S, I) bonds, though dominated by a classic Coulomb term, are therefore characterized by a very important London dispersion constituent, extremely strong relativistic effects and the two way dative-covalent Pb ↔ X electron charge delocalization contribution as revealed by the Extended Transition State Natural Orbital for Chemical Valence (ETS-NOCV) charge and energy decomposition scheme. It unravels that the pyridine-hydrazine linkers are also excellent London dispersion donors, and that together with the donor–acceptor properties of the heavy (relativistic) PbII atoms and nucleophilic counterions lead to extended self-assembling of 1–4. [ABSTRACT FROM AUTHOR]

The 2019 Faraday Discussion on the Nanolithography of Biointerfaces brought together a diverse set of interdisciplinary scientists involved in the seemingly disparate fields of materials science, nanolithography and glycoscience. The setting and format of this meeting renders the experience unique, and anyone in the audience is instantly engaged in the debate. This Faraday Discussion attracted about sixty delegates, ranging from graduate students and early career researchers to full professors. The meeting was a reflection on how far lithography techniques, tissue engineering and glycoscience have come, with the aid of scientists working at the realm of the nanoscale. True to its name, this gathering was also a discussion on what the outstanding questions in glycobiology are and how nanolithography can be appropriately applied to answer them. In this report, we will give an overview of the topics and discussions covered during the meeting and highlight the content of each session. [ABSTRACT FROM AUTHOR]

The reaction of phenoxatellurine (PT) with the known single-electron oxidizers AlCl3/CH2Cl2, [NO][SbF6] and [NO][BF4] provided the diamagnetic products [(PT)CH2Cl][AlCl4] (1), [PT2][SbF6]2 (2) and [PT3][BF4]2 (3), respectively, which were fully characterized by X-ray crystallography. The dications [PT2]2+ and [PT3]2+ present in 2 and 3 can be regarded as dimers of the elusive radical cation [PT]˙+ or as adduct between this dimer and neutral PT, respectively. The stacking between the aromatic layers of [PT2]2+ and [PT3]2+ can be best described using the pancake bonding (PB) model. The computational analysis uncovers the essential role of London dispersion effects for the stacking process and reveals the Te–Te interactions to be dominated by non-covalent bonding. The results are compared with those of the related thianthrene (TA) system. [ABSTRACT FROM AUTHOR]

Non-covalent aryl–aryl interactions for the molecular structures of three 1,2-diaryltetramethyldisilanes X5C6–(SiMe2)2–C6Y5 (X ≠ Y; X, Y = H, F, Cl) were studied by single crystal X-ray and gas electron diffraction as well as by SAPT calculations. Aryl–aryl interactions cause all to adopt exclusively rather untypical eclipsed syn-conformers in the gas phase, and C6F5–(SiMe2)2–C6Cl5 also in the solid state. [ABSTRACT FROM AUTHOR]