Covalent Organic Frameworks in Computational Design of Second-Harmonic Generation Materials: Role of Tetrel Atoms and Their Interactions.

Modern approaches to the design of nonlinear optical materials often rely on computational techniques. Here, we discuss the effects of the variation in the center tetrel atoms, Tt = C, Si, or Ge, in a series of covalent organic frameworks of the COF-102 family. The effects of halogen substitution, Hal = Cl, Br, or I on intramolecular tetrel bonding are also discussed.

Carbon-Rich Plasma-Deposited Silicon Oxycarbonitride Films Derived from 4-(Trimethylsilyl)morpholine as a Novel Single-Source Precursor.

4-(trimethylsilyl)morpholine O(CHCH)NSi(CH) (TMSM) was investigated as a single-source precursor for SiCNO films synthesis. Optical emission spectroscopy of plasma generated from TMSM/He, TMSM/H, and TMSM/NH gas mixtures revealed the presence of N, CH, H, CN, and CO species. The last two are suggested to be responsible for the lowering of carbon concentration in the films in comparison with the precursor.

Application of DUT-4 MOF structure switching for optical and electrical humidity sensing.

The threshold structural transformation of the DUT-4 metal-organic framework (MOF) from an ordered to distorted phase during exposure to ambient conditions has been revealed. The X-ray diffraction analysis, Raman and FTIR spectroscopy, scanning electron microscopy and synchronous thermal analysis have been used for investigation. The reversible effect of exposure time and humidity on such a phase transition has been confirmed.

Electron delocalization in defect-containing graphene and its influence on tetrel bond formation.

Using the advanced analyses of electron density and fermionic potential, we show how electron delocalization influences the ability of defect-containing graphene to form tetrel bonds. The C atoms of a vacancy defect can produce one nonpolar interaction, alongside a peculiar polar C⋯C bond. The latter stems from the presence of a localized electron pair on a vacancy defect C atom and the local depletion of electron localization on another C atom.

Optical Properties of Tricarboxylic Acid-Derived Carbon Dots.

Herein, we report the characterization of two types of luminescent carbon dots (CDs) synthesized by the hydrothermal treatment of citric acid and -aconitic acid by using ammonia solution as a nitrogen dopant. The lateral size range of nanoparticles for CDs lies in the range of 3-15 nm. The intense blue photoluminescence (PL) was emitted by the CDs at around 409-435 nm under the excitation of 320 nm.

Structural phase transitions in flexible DUT-8(Ni) under high hydrostatic pressure.

The behaviours of the open pore (op) and closed pore (cp) phases of the flexible Ni(ndc)(dabco) (ndc - 2,6-naphthalene dicarboxylate, dabco - 1,4-diazabicyclo[2.2.2]octane, DUT-8(Ni)) metal-organic framework under high hydrostatic pressures up to 10 GPa in isopropanol and silicone oil were studied by Raman spectroscopy.

High-pressure transformation of dithiazolylidene-dithiazolium polyiodide with N-H…N hydrogen bond: A Raman Spectroscopy study.

The insight into the behavior of polyiodides under non-ambient conditions can enrich the practical applications due to obtaining materials with adjustable and tunable conducting properties. In this work Raman spectroscopy study in the range 0 - 6.5 GPa has been performed for dithiazolylidene-dithiazolium zigzag polyiodide with N-H…N hydrogen bond.

Interplay of Intra- and Intermolecular Interactions in Solid Iodine at Low Temperatures: Experimental and Theoretic Spectroscopy Study.

This work is devoted to the discussion of structural changes in crystalline iodine under low temperature studied from experimental and theoretic points of view. Experimental Raman spectra in the temperature range 5-300 K demonstrated unusual behavior of stretching vibration at ∼180 cm with temperature. The data allowed obtaining of ω( T) functions for both external translational and internal stretching modes of I.

Electronic criterion for categorizing the chalcogen and halogen bonds: sulfur-iodine interactions in crystals.

Diversity of mutual orientations of Y-S and I-X and covalent bonds in molecular crystals complicate categorizing noncovalent chalcogen and halogen bonds. Here, the different types of S..

A Novel Family of Polyiodo-Bromoantimonate(III) Complexes: Cation-Driven Self-Assembly of Photoconductive Metal-Polyhalide Frameworks.

In the presence of different cations, reactions of [SbBr ] and I result in a new family of diverse supramolecular 1D polyiodide-bromoantimonate networks. The coordination number of Sb, as well as geometry of assembling {I } polyhalide units, can vary, resulting in unprecedented structural types. The nature of I⋅⋅⋅Br interactions was studied by DFT calculations; estimated energy values are 1.

Testing the tools for revealing and characterizing the iodine-iodine halogen bond in crystals.

To understand what tools are really suitable to identify and classify the iodine-iodine non-covalent interactions in solid organic polyiodides, we have examined the anisotropy of the electron density within the iodine atomic basin along and across the iodine-iodine halogen bond using the Laplacian of electron density, one-electron potential and electron localization function produced by Kohn-Sham calculations with periodic boundary conditions. The Laplacian of electron density exhibits the smallest anisotropy and yields a vague picture of the outermost electronic shells. The one-electron potential does not show such a deficiency and reveals that the valence electron shell for the halogen-bond acceptor iodine is always wider than that for the halogen-bond donor iodine along its σ-hole direction.

Halochromic coordination polymers based on a triarylmethane dye for reversible detection of acids.

Chromeazurol B (NaHL) is a pH-sensitive (halochromic) dye based on a hydroxytriarylmethane core and two carboxylate functional groups, which makes it suitable for the synthesis of coordination polymers. Two new coordination polymers [NaZn(HO)(L)]·3THF·3HO (1) and [Zn(HO)(μ-OH)(μ-OH)(HL)(HL)]·2THF·3HO (2) incorporating Chromeazurol B linkers have been prepared and characterised. The structure of 1 comprises pentanuclear heterometallic {ZnNa} nodes linked by six L anions to give a layered structure with a honeycomb topology.

Nontypical iodine-halogen bonds in the crystal structure of (3E)-8-chloro-3-iodomethylidene-2,3-dihydro-1,4-oxazino[2,3,4-ij]quinolin-4-ium triiodide.

Two kinds of iodine-iodine halogen bonds are the focus of our attention in the crystal structure of the title salt, C12H8ClINO(+)·I3(-), described by X-ray diffraction. The first kind is a halogen bond, reinforced by charges, between the I atom of the heterocyclic cation and the triiodide anion. The second kind is the rare case of a halogen bond between the terminal atoms of neighbouring triiodide anions.