Synthesis and Photophysical Properties of Novel Donor–Acceptor N-(Pyridin-2-yl)-Substituted Benzo(thio)amides and Their Difluoroboranyl Derivatives

Abstract

The unprecedented N-pyridin-2-yl substituted benzo(thio)amides were prepared and subsequently converted into the cyclic difluoroboranyl (BF2) derivatives. Mass spectrometry, multinuclear NMR, IR, and elemental analysis confirmed the structure of these compounds. UV/vis and fluorescence spectroscopy as well as first-principle calculations were used to study their properties. For the first time, the influence of both the O/S replacement and presence/absence of the BF2 moiety on the photophysical properties of compounds exhibiting charge transfer properties were examined experimentally and theoretically. We show that the sulfur-containing compound has a much smaller emission quantum yield than its oxygen counterpart. The fluorescence quantum yield is much higher upon formation of the difluoroboranyl complex.

Difluoroboranyl derivatives as efficient panchromatic photoinitiators in radical polymerization reactions

“…& Beata Jędrzejewska beata@utp.edu.pl altering atoms through, which the BF 2 group is attached to the molecule [4,5] or by changing the conjugation path [6,7] or their structure from symmetrical to unsymmetrical one [8][9][10]. Among various compounds carrying the BF 2 moiety the most common are boron-dipyrromethenes (BODIPYs) [8,11].…”

Tuning the Mechanical and Thermal Properties of Emissive ß-diketones, Modulating Electronic and Molecular Packing Effects

“…29 Evidence of charge transfer can be found in the MO diagrams of molecules like the difluoroboron β-diketonate, BF2dbmp(OMe)2 (Figure 1.5). 30 Examination of the highest occupied molecular orbital (HOMO) shows electron density localized on the dioxaborine ring. Upon UV excitation to the lowest unoccupied molecular orbital (LUMO), electron density shifts to the out-of-plane phenyl ring, demonstrating charge transfer.…”

“…One example that illustrates the differences between molecules exhibiting ACQ and AIE are the α-substituted boron difluoride β-diketonates, BF2dbe(OMe)2 and BF2dbt(OMe)2 ( Figure 1.8). 30 The β-tetralone derivative, BF2dbt(OMe)2, is strapped and molecular motion is hindered.…”

“…For instance, the Fraser lab has modulated optical properties of stimuli responsive BF2bdk materials via alkyl chain length, 92,93 substitution at the α-position, and with arenes substitution. 30,88 Recently,Sket et al, have shown that the ML active, methoxy-substituted BF2bdk 1-phenyl-3-(3,5dimethoxyphenyl)-propane-1,3-dione can be crystallized as uniquely emissive polymorphs whose formation is partially governed by the different conformations of the methoxy substituents. 73 Furthermore, heavy atom substitution results in mechanochromic luminescence quenching (MLQ) where emission is quenched upon smearing due to enhanced intersystem crossing to the oxygen sensitive triplet state.…”

“…Optical Properties of DMA Derivatives in Dichloromethane SolutionAccording to the emission of DMA dyes in dichloromethane, there is a strong correlation between the emission properties of each dye and the electron withdrawing ability of the para substituent. With the exception of DMA-OMe, all dyes exhibit radiative lifetimes (τrad > 4.0 ns) corresponding to ICT emission 30. The radiative lifetime observed in DMA-OMe solutions was borderline (3.1 ns).…”