Solvatochromic and Proton-Responsive characteristics of Bi-1,3,4-Oxadiazole derivatives with symmetric dimethylamino substitution.

D-A molecules find extensive use in intelligent stimulus-response systems due to their exceptional attributes, including high sensitivity, rapid response, wide compatibility, and structural adaptability. The strength of Intramolecular Charge Transfer (ICT) plays a pivotal role in determining the performance of these devices. To enhance the ICT strength and explore new applications for D-A molecules, we meticulously designed a pair of symmetric dimethylamino-substituted bi-1,3,4-oxadiazole derivatives (DMAOXD and DMAOXDBEN).

Multicolor fluorescence switching material induced by force and acid.

A novel D-A-D chromophore TBQM based on triphenylamine, acylhydrazone and dimethylamino was synthesized, and the emission properties of TBQM was studied in solutions as well as in aggregated state. TBQM showed obvious solvatochromism in different solutions. In addition, the reversible multicolor fluorescence switching properties under the stimulation of external forces and acid were also obtained.

Force-, heat- and acid-induced fluorescent switching properties of an anthracene-based hydrazide derivative.

A novel anthracene-based hydrazide derivative (3,4-ENS) was designed and synthesized, and 3,4-ENS can form stable organogel in dimethyl sulfoxide (DMSO) solvent. Firstly, 3,4-ENS xerogel from DMSO exhibits mechanofluorochromic property and its maximum emission shifts from 433 nm to 484 nm upon grinding. Secondly, DMSO xerogel exhibits thermofluorochromic behavior and its maximum emission shifts from 433 nm to 481 nm upon heating at 110 °C.

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.

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.

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.

Enhancement of intramolecular charge transfer strength in diphenylamine substituted symmetric 1,3,4-oxadiazole derivatives.

The intramolecular charge transfer characteristic of two diphenylamine substituted symmetric 1,3,4-oxadiazole derivatives (DPAOXD and DPAOXDBEN) was studied through a combination of experimental techniques and theoretical calculations. Significant enhancement of intramolecular charge transfer strength has been found in both these compounds through molecular structure modification. The experimental result found only a small red shift in the absorption spectra (∼15 nm) but a very large red shift in the emission spectra (∼114 nm for DPAOXD and ∼140 nm for DPAOXDBEN) with increasing solvent polarity, indicating a large extent charge transfer occurred in their excited state.

Lamellar-cubic transition of a dihydrazide derivative and its effect on the gel stability.

N,N'-Bis(4-n-alkyloxybenzoyl)hydrazine (4D16) was demonstrated to show three different aggregates, i.e. a crystalline cubic phase and two kinds of lamellar structure with layer spacings of 34.

Exploring the difference in xerogels and organogels through observation.

Solvent-gelator interactions play a key role in mediating organogel formation and ultimately determine the physico-chemical properties of the organogels and xerogels. The ethanol organogels of 1,4-bis[(3,4,5-trihexyloxy phenyl)hydrazide]phenylene (TC6) were investigated by FT-IR, Raman and fluorescence spectra, and XRD, and it was confirmed that the intermolecular interaction and aggregation structure of TC6 ethanol organogels were quite different from those of xerogels. Simultaneously, unprecedented phase transition from organogel to suspension upon heating was observed in ethanol organogel, and the suspension phase exhibited lytropic liquid crystalline behaviour with a rectangular columnar structure.

Substituent Effect on Intramolecular Charge Transfer of Symmetric Methoxy-Substituted Bi-1,3,4-oxadiazole Derivatives.

Intramolecular charge-transfer characteristics of a series symmetric methoxy -substituted bi-1,3,4-oxadiazole derivatives with various substituted positions and quantities have been studied with a combination of experimental techniques and theoretical calculations to investigate the substituent effect. Different degrees of fluorescence red shift in polar solvents are observed in these compounds. The meta-substituted molecule (BOXD-m-OCH) exhibits a larger red shift (82 nm) than the other two monosubstituted molecules, BOXD-o-OCH (40 nm) and BOXD-p-OCH (37 nm); the polysubstituted molecules BOXD-D1 and BOXD-T1 show 80 and 104 nm red shifts, respectively, which are obviously larger than the monosubstituted molecules.

Observation of Morphology and Structure Evolution during Gelation of a Bis(Anhydrazide) Derivative.

A new bis(anhydrazide) derivative containing cyclohexyl terminal groups (compound 1) was synthesized, and its gelation process was investigated. Compound 1 showed both thermal-induced gelation (T-gel) and sonication-induced gelation (S-gel) in alcohols. We investigated the gelation process of compound 1 in ethanol by different techniques.

E-Z isomerization of the -C[double bond, length as m-dash]N- bond in anthracene-based acylhydrazone derivatives under visible light.

The photoresponsive behaviour of AHP-mB8 upon irradiation by visible light was demonstrated to be due to the E-Z isomerizations of the -C[double bond, length as m-dash]N- group, rather than the photodimerization of anthracene groups. In addition, the Z-isomer of AHP-mB8 was stable at room temperature. AHP-mB8 organogels showed visible light induced gel-sol transition and its mechanism was proposed.

Gelation behaviour of a bent-core dihydrazide derivative: effect of incubation temperature in chloroform and toluene.

In this work, a new kind of gelator, 1,3-bis[(3,4-dioctyloxy phenyl) hydrazide]phenylene (BP8-C), containing two dihydrazide units as the rigid bent-core, has been synthesized and investigated. It was demonstrated that BP8-C is an efficient gelator which can gel various organic solvents, such as ethanol, benzene, toluene, chloroform, etc. Both an opaque gel (O-gel) and a transparent gel (T-gel), which is more stable, were obtained with BP8-C in chloroform at different incubation temperatures.

Ultrasound-induced controllable morphology and growth dimension in a dihydrazide-based self-assembly system.

We have demonstrated ultrasound-induced organogels based on twin-tapered dihydrazide derivatives, oxalyl acid N,N-di(3,4,5-trialkoxybenzoyl)hydrazide (FH-Tn). Ultrasound irradiation has been proved to influence gel properties at micro-levels. Different self-assembled structures from entangled fibers to tube-like structures and nanoparticles can be easily manipulated by tuning irradiation time and water bath temperature.

A simple structural hydrazide-based gelator as a fluoride ion colorimetric sensor.

A 4-nitrobenzohydrazide derivative, N-(3,4,5-octyloxybenzoyl)-N'-(4'-nitrobenzoyl)hydrazine (C8), was synthesized. It could form stable gels in some of the tested organic solvents. The wide-angle X-ray diffraction analysis showed that the xerogels exhibited a layered structure.

5,5'-Bis(naphthalen-2-yl)-2,2'-bi(1,3,4-oxadiazole).

The title mol-ecule, C(24)H(14)N(4)O(2), lies on an inversion centre and the asymmetric unit containg one half-mol-ecule. The naphthalene ring systems are twisted slightly with respect to the oxadiazole rings, making a dihedral angle of 1.36 (6)°.

Experimental and theoretical study on molecular aggregation and its effect on the photo-physical properties of the mesogenic bi-1,3,4-thiadiazole derivative.

A bi-thiadiazole derivative, 5,5'-bis(4- tetradecyloxyphenyl)-2,2'-bi-1,3,4-thiadiazole (BTD-14), was revealed to exhibit an extremely stable thermotropic SmC phase and very interesting aggregation behavior in solutions. H- and J-aggregates could be formed simultaneously in chloroform solutions of BTD-14 with moderate concentration (10(-4) M), and the population of J-aggregates enlarges during further concentration increase. All monomers, H-aggregates and J-aggregates in solutions could be reserved in the drop-cast films, and both the presence of J-aggregates and the energy transfer path from H-aggregates to J-aggregates were considered to contribute to the relative high solid state fluorescence quantum yield (33%).

Solvent-induced helix superstructure in achiral dumbbell-shaped hydrazine derivatives.

We studied hydrogen-bonding assemblies in a series of dumbbell-shaped hydrazine derivatives, namely oxalyl N',N'-bis(3,4-dialkoxybenzoyl)-hydrazide (BFH-n, n = 4, 6, 8, 10) and oxalyl N',N'-dibenzoyl-hydrazide (FH-0). It has been demonstrated that NH-1 protons of BFH-n precipitated from tetrahydrofuran (THF) or dimethylformamide (DMF) were involved in intramolecular H-bonding to form 6-membered rings. Meanwhile, NH-2 protons of BFH-n precipitated from THF formed intermolecular hydrogen bonds with C═O groups of neighboring molecules, while NH-2 protons of BFH-n precipitated from DMF formed intermolecular hydrogen bonds with C═O group of neighboring DMF molecules.

Classification of the hydrogen-bonding species in a series of novel hydrazide based azobenzene derivatives investigated by two-dimensional correlation infrared spectroscopy and molecular modeling.

Classification of hydrogen-bonding species in a series of novel hydrazide modified p-methoxyazobenzene derivatives, 4-{n-[4-(4-methoxy-phenylazo)-phenoxy]-alkoxy}-benzoic acid hydrazide (Dn, n = 3, 6, 10) are performed in the present study. Temperature-dependent infrared (IR) spectra of Dn have been measured to investigate the thermal stability of the weak intermolecular interactions, such as hydrogen bonding among hydrazide moieties, pi-pi stacking among aromatic groups, and hydrophobic interaction between alkyl chains. In order to reveal the hydrogen bonding formed between NH, NH2, and CONH groups efficiently, two-dimensional (2D) correlation spectra have been constructed in the thermal sensitive spectral regions of (a) 3500-3100 cm(-1) and (b) 1700-1450 cm(-1), separately, and it have also been constructed between these two spectral regions.