Synthesis, structures and photophysical properties of boron–fluorine derivatives based on pyridine/1,8-naphthyridine
作者:Zhensheng Li、Xiaojun Lv、Yong Chen、Wen-Fu Fu
DOI:10.1016/j.dyepig.2014.01.022
日期:2014.6
Three boron fluorine complexes B1-B3 containing pyridine/1,8-naphthyridine were synthesized and structurally characterized. Compounds B1 and B2 exhibited strong fluorescence in solution and solid state. The solvent-dependent luminous properties and large Stokes shift in solution could be explained by intramolecular charge transfer, which is confirmed by time-dependent density functional theory calculation. The absolute quantum yield of B1 in powder form reached 0.48 because of inhibiting planar pi...pi stacking. Single-crystal X-ray diffraction analyses of B1 and B2 revealed that weak intermolecular C H...F and H...pi interactions hinder further stacking of pi...pi dimers, consequently preventing aggregation-induced quenching. Complex 113, composed of boron-dipyrromethene and 1,8-naphthyridine fluorophore, had potential applications as a pH ratiometric fluorescent sensor. (c) 2014 Elsevier Ltd. All rights reserved.
Solid-emissive boron–fluorine derivatives with large Stokes shift
作者:Miaofu Mao、Shuzhang Xiao、Jianfeng Li、Ying Zou、Ronghua Zhang、Jiarong Pan、Feijun Dan、Kun Zou、Tao Yi
DOI:10.1016/j.tet.2012.04.052
日期:2012.6
Novel BOPIM (boron 2-(2'-pyridyl)imidazole complex) derivatives with large Stokes shift were efficiently synthesized through two-step reactions, starting from commercially available 2-pyridinecarboxaldehyde and alpha-diketone. The dyes exhibit high fluorescent intensity in solution and also in solid state due to the intermolecular non-planar interactions. According to X-ray single crystal measurements, the non-covalent interactions (such as C-H center dot center dot center dot F-B, etc.) play important role in inhibiting planar pi-pi stacking, and the existence of terminal phenyl rings increases the electronic density of pi system, which facilitates the charge transfer from the electron-donating pi system to the electron-accepting boron moiety. DFT calculation based on X-ray crystallographic analysis was carried out for compound 2, giving consistent results with photophysical measurements. (C) 2012 Elsevier Ltd. All rights reserved.
Structure–property correlation of solid-emissive boron–fluorine derivatives
作者:Qiong Cao、Shuzhang Xiao、Miaofu Mao、Xiaohong Chen、Sa Wang、Ling Li、Kun Zou
DOI:10.1016/j.jorganchem.2012.07.043
日期:2012.10
A series of solid-emissive BOPIM (boron 2-(2-pyridyl)imidazole complex) dyes, bearing electron-donating or -withdrawing substituents (methoxy, hydrogen, or nitro), are facilely synthesized. The compounds were characterized by H-1 NMR, C-13 NMR and MS. X-ray single crystal diffractions of BOPIM 1 and 2 indicate that nonplanar rigid structures were formed through intermolecular non-covalent interactions. Due to these non-covalent interactions, these dyes exhibit intense fluorescence in solution and also in solid state. According to H-1 NMR analysis, electronic effect of the substitutes plays an important role in contribution to these BOPIMs' electronic states. The photophysical measurements reveal that electron-donating groups (methoxy) lead to significant bathochromism of the absorption and emission. In contrast, electron-withdrawing moieties (nitro) play the reverse role. However, BOPIM 3 bearing nitro groups emits long wavelength fluorescence in solid state, probably due to the formation of intermolecular hydrogen bond. This work elucidates the spectroscopic structure-property relationship of solid-emissive BOPIMs, which would be valuable for design of solid-emissive dyes. (C) 2012 Elsevier B. V. All rights reserved.