Design, synthesis and properties of near-infrared molecular switches containing a fluorene ring

Abstract

Three molecular switches containing a fluorene ring were designed and synthesized. The introduction of the amino group substituted fluorene ring resulted in the target molecular switches having some optical properties in the near-infrared region. It was demonstrated that the N-substituents on the fluorene rings and the switch units both had great influence on the molecular switch optical properties including the absorption maximum, absorption intensity and fluorescence quantum yield. The open-ring forms and showed obvious solvatochromic behaviour. The closed-ring forms and showed obvious hydrochromic behaviour in MeCN/water binary solvent systems and acidichromic behaviour in MeCN solution with high reversibility. Especially, the distinct off-on fluorescence signal in the near-infrared region using the stimuli of acid means that the designed compounds have great potential application value in the field of biological sensing.

Thioxanthylium Cations: Highly Reversible Hydrochromic Mate‐rials with Tunable Color and Moisture Sensitivity

“…In addition, we have demonstrated the ability to tune colour, fluorescence, and moisture‐sensitivity of Tx + via facile structural modification, such as the use of different aliphatic, aromatic, fused aromatic, electron‐rich, and electron‐deficient groups functionalized at the 9‐ or 2,7‐ positions of the thioxanthene core. While colour‐tuning has been reported in some systems such as the spiro‐compounds molecular switches [5a,b] and PDA‐based system, [4] the modulation of moisture‐sensitivity has not been explicitly studied in other reported hydrochromic systems. Many of our Tx + cations are extremely moisture‐sensitive, and an ambient humidity level or a trace amount of water in organic solvents (∼1–10 mM) being sufficient to fully decolourize them.…”

Single Molecule-Based Electronic Devices: A Review

“…Electrochemical or chemical environment-induced rotaxane molecular switches have long been reported. 67 Chen et al 68 designed and synthesized three molecular switches containing°uorene ring, as shown in Fig. 4.…”

Development of highly sensitive metal-ion chemosensor and key-lock anticounterfeiting technology based on oxazolidine

“…In addition, a wide range of oxazolidine derivatives could be synthesized by using various aromatic aldehyde compounds substituted with different electron donor and electron withdrawing groups. Oxazolidine derivatives display various stimuli-chromism, such as hydrochromism, solvatochromism, acidochromism, and photochromism, depending on the functional groups on their chemical structure 45 , 47 – 50 . Oxazolidine displays various coloration and fluorescence emission in different media, depending on interactions of different functional groups on the indolenine ring or benzaldehyde structure with the surrounding media 45 , 51 – 55 .…”