An anthracene-based organogel with colorimetric fluoride-responsive and fluorescence-enhanced properties

Stimuli-responsive behavior of naphthyl acylhydrazone derivative and its application in information security protection

Acylhydrazone derivatives containing naphthyl group, namely, 3,5-bis-octyloxy-benzoic acid naphthalen-1-ylmethylene-hydrazide (NTH-mB8) and 4-methoxy-benzoic acid naphthalen-1-ylmethylene-hydrazide (NTH-P1) were synthesized. π-π interactions between naphthalene groups and -N-H···O=C- intermolecular hydrogen bondings were observed in NTH-P1 single crystal, in which -C=N- bonds exhibited trans-isomer. NTH-mB8 showed photo-responsive behavior due to photo-induced trans-cis isomerizations of -C=N- bonds. Interestingly, the NTH-mB8 films fumed by trifluoroacetic acid (TFA)/triethylamine (TEA) (or standing at room temperature) vapors show reversible fluorescence on/off switching property. The cast film of NTH-mB8 exhibited almost no fluorescence. The NTH-mB8 film fumed by TFA vapor exhibited intensive cyan emission, which was quickly quenched by TEA vapor. The reversible remarkable fluorescence on/off switching properties suggested that the organic solution of NTH-mB8 could be used as security ink without needing a covering reagent in information security protection.

Multistimuli-Responsive Fluorescent Organogelator Based on Triphenylamine-Substituted Acylhydrazone Derivative

A new triphenylamine-based acylhydrazone derivative (TPAH-B8) was synthesized. TPAH-B8 could form organogels in cyclohexane through ultrasonic treatment. A typical gelation-induced fluorescence enhancement property was observed, which was attributed to the formation of J-aggregate in the gel state. More interestingly, TPAH-B8 exhibited multistimuli responsive behaviors. First, TPAH-B8 showed a solvatochromic effect, with the emission color changing from blue to cyan with the change in solvent from nonpolar cyclohexane to polar dimethyl sulfoxide (DMSO). Second, TPAH-B8 showed a reversible mechanofluorochromism. The xerogel of TPAH-B8 emitted a blue fluorescence, while the fluorescence color changed to cyan after grinding. The cyan and blue colors could be repeated with the treatment of grinding and annealing, which was explored and ascribed to the transformation between crystalline and amorphous states. Third, TPAH-B8 revealed acidochromic property. The fluorescence color of TPAH-B8 in organogel and solid states could be switched by trifluoroacetic acid (TFA)/triethylamine (TEA). This work not only demonstrated the multistimuli-responsive fluorescent properties of TPAH-B8 but also offered an easy way to develop new kinds of multistimuli-responsive fluorescent materials.

A colorimetric and fluorescent sensor for the detection of both fluoride ions and trifluoroacetic acid based on acylhydrazone derivatives

An acylhydrazone-based colorimetric and fluorescent sensor (PAH-8) for the detection of fluoride ions (F-) and trifluoroacetic acid (TFA)/triethylamine (TEA) has been studied. PAH-8 solution and organogel are highly selective and sensitive to F- among various tested anions (F-, Cl-, Br-, AcO-, and H2PO4-) in DMSO. Upon addition of F-, the maximum absorption wavelength of PAH-8 in DMSO solution shows a big red shift from 377 nm to 464 nm with a marked color change from colorless to yellow, and the fluorescence emission also displays a red shift from 438 nm to 532 nm with its fluorescence emission switching from blue to yellow. Both Job's plot and the Benesi-Hildebrand plot confirm a 1 : 1 stoichiometric relationship between PAH-8 and F-. The detection limit of PAH-8 for the analysis of F- can reach 8.31 × 10-7 M. Very interestingly, an expeditious 'naked eye' detection of F- can be realized by the reversible gel-sol transition, along with a color change from slight yellow to bright red and fluorescence quenching. In addition, the cast film of PAH-8 (the solution was developed from the DMSO gel upon the addition of TBAF) can detect water in air by color switching or fluorescence on/off. In both solution and solid states, PAH-8 also exhibits obvious acid-base stimulated fluorescence conversion. The solution of PAH-8 can convert the blue emission into intensive sky blue emission after adding trifluoroacetic acid (TFA), and the solid film exhibits no fluorescence after fuming with TFA vapors, while fuming with triethylamine (TEA) vapors resulted in intensive green emission.

A mechano-responsive fluorescent xerogel based on an anthracene-substituted acylhydrazone derivative

AHBP-8 can form a stable organogel and enhanced fluorescence emission has been observed after gelation. The AHBP-8 xerogel exhibited favorable mechano-fluorochromism behavior.

Colorimetry and phase transition characteristics in sensing fluoride anion based on hydrazide organogelators

Colorimetry and phase transition characteristics in sensing fluoride anions have been achieved based on hydrazide organogelators.

Gelation behaviour and gel properties of two-component organogels containing a photoresponsive gelator

Herein, we report the gelation behaviour and gel properties of two-component organogels consisting of 1,4-bis[(3,4-bisoctyloxyphenyl) hydrozide] phenylene (BPH-8) and a photoresponsive gelator 4-[3,5-(bisoctyloxyphenyl)]-9-anthracene formyl hydrazine (MB8).

E–Z isomerization of the –CN– bond in anthracene-based acylhydrazone derivatives under visible light

The E–Z isomerizations of the –CN– group upon visible light irradiation induced the photoresponsive behaviour of AHP-mB8.