TADF Invariant of Host Polarity and Ultralong Fluorescence Lifetimes in a Donor-Acceptor Emitter Featuring a Hybrid Sulfone-Triarylboron Acceptor.

10H-Dibenzo[b,e][1,4]thiaborinine 5,5-dioxide (SO2B)-a high triplet (T =3.05 eV) strongly electron-accepting boracycle was successfully utilised in thermally activated delayed fluorescence (TADF) emitters PXZ-Dipp-SO2B and CZ-Dipp-SO2B. We demonstrate the near-complete separation of highest occupied and lowest unoccupied molecular orbitals leading to a low oscillator strength of the S →S CT transition, resulting in very long ca.

Heavy-Atom Free Organoboron Complexes As Triplet Excited States Photosensitizers for Singlet Oxygen Activation.

Herein, we present a new strategy for the development of efficient heavy-atom free singlet oxygen photosensitizers based on rigid borafluorene scaffolds. Physicochemical properties of borafluorene complexes can be easily tuned through the choice of ligand, thus allowing exploration of numerous organoboron structures as potent O sensitizers. The singlet oxygen generation quantum yields of studied complexes vary in the range of 0.

Experimental and Theoretical Insights into Molecular and Solid-State Properties of Isomeric Bis(salicylaldehydes).

A series of five bis(salicylaldehydes), including four isomeric compounds based on a benzene scaffold and a closely related naphthalene derivative, were investigated in order to elucidate the impact of resonance effects and intramolecular hydrogen bonds (HBs) on the macroscopic properties of these systems. Density functional theory (DFT) computations revealed important differences between isomers on the molecular level, which was reflected in different charge distributions, aromatic C-C bond orders, and aromaticity characters. The consequences of these features were evidenced by the UV-vis absorption spectra: for 1,3-diformyl-4,6-dihydroxybenzene (), the longest wavelength absorption band is observed at 285 nm, while its isomers 1,4-diformyl-2,5-dihydroxybenzene (), 1,4-diformyl-2,3-dihydroxybenzene (), and 1,2-diformyl-3,6-dihydroxybenzene () are characterized by absorption in the visible range (379-407 nm).

Cationic and Betaine-Type Boronated Acridinium Dyes: Synthesis, Characterization, and Photocatalytic Activity.

A series of isomeric boronated acridinium dyes were obtained by reactions of 10-(4'-octyloxyphenyl) functionalized 9(10)-acridanone derivative with lithiated phenylboronic azaesters followed by aromatization with perchloric acid. The effect of the position of boronic group attached at ortho, meta, and para positions of the 9-phenyl ring on the photophysical properties was investigated. Conversion to related betaine trifluoroborato-substituted compounds was successfully performed, and the effect of this structural change on UV-vis absorption and fluorescence spectroscopy characteristics was established.

The effect of locking π-conjugation in organoboron moieties in the structures of luminescent tetracoordinate boron complexes.

A series of 8 luminescent borafluorene complexes were extensively studied both experimentally and theoretically in order to elucidate the effect of organoboron moiety rigidification on the physicochemical properties of these compounds. Due to the spiro geometry of the boron atom, borafluorene and ligand units are perpendicularly aligned, which considerably affects the flexibility of the molecule as well as its solid-state structure. Through comparative analysis with close diphenyl analogues, we show how these structural features influence the thermal, photoluminescent and charge mobility behaviour of the studied compounds.

Antimicrobial and KPC/AmpC inhibitory activity of functionalized benzosiloxaboroles.

A series of 22 benzosiloxaboroles, silicon analogues of strong antimicrobial agents - benzoxaboroles, have been synthesized and tested against β-lactamases KPC- and pAmpC-producing strains of Gram-negative rods. Comprehensive structural-property relationship studies supported by molecular modelling as well as biological studies reveal that 6-B(OH)-substituted derivative 27 strongly inhibits the activity of cephalosporinases (chromosomally encoded AmpC and plasmid encoded CMY-2) and KPC carbapenemases. It also shows strong ability to inhibit growth of the strains producing KPC-3 when combined with meropenem.

The study of interactions with a halogen atom: influence of NH group insertion on the crystal structures of meta-bromonitrobenzene derivatives.

Halogen atoms in molecular crystals may be involved in various interactions, often playing a very important role in structure stabilization. By introducing electron-donating groups, such as NH, the electron density of the molecule is changed and thus interactions with the bromine substituent may alter. Herein, the crystal structures of meta-bromonitrobenzene and its NH-substituted derivatives are analyzed.

The effect of conformational isomerism on the optical properties of bis(8-oxyquinolato) diboron complexes with a 2,2'-biphenyl backbone.

A fluorescent bis(8-oxyquinolato) diborinic complex with a central 2,2'-biphenyl backbone 1 and its octafluoro analogue 2 were synthesized to study the optical-structural relationship of sterically encumbered molecules featuring close intramolecular π-stacking interactions involving chromophore units. The crystal structure of 1 revealed a unique π-stacked arrangement of two pendant phenyl groups and two 8-oxyquinolato ligands (Q) located in the inner part of the complex. Unlike 1, the closely related complex 2 features conformational isomerism, and two major forms, namely 2-syn and 2-anti, are observed in solution to a varying extent depending on the solvent polarity.

At Long Last: Olefin Metathesis Macrocyclization at High Concentration.

Macrocyclic lactones, ketones, and ethers can be obtained in the High-Concentration Ring-Closing Metathesis (HC-RCM) reaction in high yield and selectivity at concentrations 40 to 380 times higher than those typically used by organic chemists for similar macrocyclizations. The new method consists of using tailored ruthenium catalysts together with applying vacuum to distill off the macrocyclic product as it is formed by the metathetical backbiting of oligomers. Unlike classical RCM, no large quantities of organic solvents are used, but rather inexpensive nonvolatile diluents, such as natural or synthetic paraffin oils.

An intramolecular ortho-assisted activation of the silicon-hydrogen bond in arylsilanes: an experimental and theoretical study.

An intramolecular activation of the Si-H bond in arylsilanes by selected ortho-assisting functional groups based on boron, carbon and phosphorus was investigated experimentally and by means of theoretical calculations. The major conclusion drawn is that the presence of a negatively charged oxygen atom in the functional group is essential for providing effective chelation to the silicon atom which in turn results in the increased hydridic character of a resulting five-coordinated species. In contrast, an intermolecular attack of hydroxide on the silicon atom in aryldimethylsilane results in the activation of the silicon-aryl bond.

Highly Fluorescent Red-Light Emitting Bis(boranils) Based on Naphthalene Backbone.

Ten bis(boranils) differently substituted at the boron atom and iminophenyl groups were synthesized from 1,5-dihydroxynaphthalene-2,6-dicarboxaldehyde using a simple one-pot protocol. Their photophysical properties can be easily tuned in a wide range by the variation of substituents. Their absorption and emission spectral bands are significantly red-shifted (λ = 495-590 nm, λ = 533-683 nm) when compared with simple boranils, whereas fluorescence quantum yields are strongly improved to reach 83%.

Tuning of the colour and chemical stability of model boranils: a strong effect of structural modifications.

A series of diarylborinic complexes with salicydeneaniline ligands bearing various functional groups at the 6-position have been synthesized in high yields by applying a straightforward one-pot multicomponent protocol. UV-Vis measurements revealed the influence of electronic character of substituents on the observed maximum of emission (λem). This has been confirmed by a relatively strong linear correlation (R(2) = 0.