Dynamic Coordination between a Triphenylamine-Functionalized Salicylaldehyde Schiff Base and a Copper(II) Ion

α-Cyanostilbene-based Molecule with the Synergistical Mechanisms of AIE, ESIPT and TICT: A New Schiff Base Probe for Selective Detection of Fe3+ and Reversible Response to HCl/NH3 Vapor

We designed and synthesized a new Schiff base probe, which incorporated the salicylaldehyde-analogue α-cyanostilbene and benzophenone hydrazone by the imine linkage. Its chemical structure was verified by FT-IR, MALDI-TOF-MS, HR-MS and 1H/13C NMR technologies. It could exhibit a red fluorescence based on the synergistical effects of aggregation-induce emission (AIE), excited-state intramolecular proton transfer (ESIPT) and twisted intramolecular charge-transfer (TICT) in the aggregation or solid states. Interestingly, the TLC-based test strip loaded with the target compound showed the reversible fluorescence response to amine/acid vapor and on-site visual fluorescence quenching response to Fe3+. In THF/water mixtures (fw = 90%, 10 µM, pH = 7.4), the detection limit (DL) and the binding constant (Ka) of the developed probe towards Fe3+ were evaluated as 5.50 × 10- 8 M and 1.69 × 105, respectively. The developed probe was successfully applied for the detection of Fe3+ with practical, reliable, and satisfying results.

A unique N-heterocyclic oligo(N,O-donor) salamo-Ni(II)-based probe for highly selective fluorescence detection of Cr2O72

A unique fluorescent probe Ni-DAS was developed by a nitrogenous heterocyclic oligo(N,O-donor) salamo-based compound DAS. DAS exhibits AIE and ESIPT effects which are extremely infrequent in salamo-based multi-oxime compounds. In addition, Ni-DAS can be used as a fluorescent probe with high selectivity and sensitivity to recognize Cr2O72- in DMF with 80 % water content, which enhances the value of the probe for application in real environments, and outperforms most similar molecular fluorescence probes. The probe Ni-DAS can recognize Cr2O72- by oxidative hydrolysis of C = N bonds, which promotes further research on theory of C = N bond hydrolysis, and the binding ratio and recognition mechanism were verified and supported by relevant theoretical calculations (DFT & MESP). The experiments showed that the probe Ni-DAS can be used for ion detection in real environments. It provides a new strategy for the oxidative hydrolysis of C = N bond and the structure of salamo-based compounds with AIE nature, and offers new ideas for study ion recognition and acidity detection.

Spectroscopic and theoretical studies on a novel bis(salamo)-like probe for highly effective fluorimetric-colorimetric identification of Fe3+ and Cu2+ in aquo-organic medium

A novel bis(salamo)-type sensor FT for fluorescence-colorimetric recognition of Fe3+/Cu2+ has been created, which revealed significant fluorescent performance and colorimetric sensing ability for Cu2+ and Fe3+ ions, superior to other related competitive metal ions. Interestingly, the binding of the FT probe with Cu2+ ions manifested an instant color change from colorless to red in sunlight, which is detectable by the naked-eye, and a fluorescence turn-off response under UV light for Fe3+ and Cu2+. The results demonstrated that the probe exhibits better sensitivity, greater affinity and lower limit of detection leading to quick response time in an aquo-organic medium. The excited state property of the FT probe and in the presence of Cu2+/Fe3+ was evaluated on the basis of DFT & TD-DFT results. Furthermore, test strips have been provided for convenient monitoring of Cu2+ and Fe3+ ions by naked eye and fluorescence method.

Semicarbazide-based fluorescent probe for detection of Cu2+ and formaldehyde in different channels

Two fluorescent sensors with the receptor semicarbazide respectively at 7- (CAA) and 3-position (CAB) of coumarin were designed and synthesized. CAA exhibits fluorescence turn-on response to Cu²⁺ by triggering the intramolecular charge transfer (ICT) process via Cu²⁺-catalyzed hydrolysis, and can detect formaldehyde (FA) at different channel by inhibiting the photo-induced electron transfer (PET). However, CAB displays quite different responses: the photophysical properties hardly changed in the presence of FA; while a three-stage fluorescence response of fast quenching, steady increasing and slowly decreasing was found upon addition of Cu²⁺. The high selectivity enabled CAA a good candidate for quantification of Cu²⁺ and formaldehyde as well as bioimaging Cu²⁺ in living cells. Good linear relationships between the fluorescence intensity and analyte concentration were observed in the range of 0.1-30 μM for Cu²⁺ and 1.0-50 μM for FA, and their detection limits (LOD) were calculated to be 0.43 μM and 1.92 μM (3δ/k), respectively.

AIE -active TPA modified Schiff base for successive sensing of Cu2+ and His via an on-off-on method and its application in bioimaging

In this article, a novel triphenylamine-modified salicylaldehyde Schiff base 2-(((4-(diphenylamino)phenyl)imino)methyl)-4-(pyridine-4-yl)phenol (HL) was synthesized and structurally characterized. HL possessed D-π-A structure and exhibited typical AIE property in THF/H₂O. It was applied to selectively recognize Cu²⁺ through an on-off mode in THF/H₂O (1/9, v/v), and the fluorescence attenuation was attributed to a paramagnetic quenching effect of Cu²⁺ together with the abatement of HL aggregates. Hence, the detection limit achieved was as low as 1.32 × 10^-7 M. The spectroscopic and ESI-HRMS results revealed a 1 : 2 complexation ratio of Cu²⁺ with HL. The mechanism for sensing Cu²⁺ was further confirmed by performing DFT calculations. Owing to the large affinity between Cu²⁺ and His, the resultant CuL2 system was further used to detect His via the off-on method based on the displacement of ligands. The detection limit for His reached 5.14 × 10^-8 M. Furthermore, HL was available to prepare handy indicator papers for the on-site recognition of Cu²⁺ and His. Confocal fluorescent imaging demonstrated that HL could sequentially respond to intracellular Cu²⁺ and His.

Crystal structure of N 2,N 6-bis(2-(((E)-naphthalen-1-ylmethylene)amino)phenyl)pyridine-2,6-dicarboxamide, C41H29N5O2

C41H29N5O2, monoclinic, P21/c (no. 14), a = 12.4919(10) Å, b = 19.4010(15) Å, c = 13.2741(11) Å, β = 103.319(2)°, V = 3130.5(4) Å3, Z = 4, R gt (F) = 0.0557, wR ref (F 2) = 0.1746, T = 293(2) K.

Controllable Physical Synergized Triboelectricity, Shape Memory, Self-Healing, and Optical Sensing with Rollable Form Factor by Zn cluster

To build devices offering users comfortable experience, it is important to focus on form factor and multifunctionality. In this study, for the first time, multifunctional Zn clusters with shape memory, self-healing, triboelectricity, and optical sensing synergized with rollable form factor are designed and fabricated by coordinating COO^- and Zn²⁺ . As pore forming agent, Zn clusters produce hierarchical porous structure depending on Zn amount. Zn clusters are applied as message transmitters and charge containers in optical sensing and corona charge injection, respectively. Moreover, Zn clusters in PVB-COO-Zn serve as positive tribomaterial due to Zn ion doping effect, increasing the output performance as the Zn amount reaches 20 wt%. In addition, injecting positive charge into PVB-COO-Zn 20 lead to more than 24 times increase in output performance compared to those of non-porous structures. The reversibility of Zn clusters endows shape memory and self-healing, synergized with the rollable form factor. The rollability is implemented using the long alkyl chain and the energy absorption of porous structure, providing damage resistance. The advancements in this work provide opportunities for multifunctional and unique applications (shape memory rotating-triboelectric nanogenerator, rollable self-healing touchpad, hidden tag) synergized with rollability that accomplishes working in broadened condition in near future.

A fluorescent sensor array based on three kinds of carbon dots for identification of hydroxybenzaldehyde and nitrobenzaldehyde isomers

A fluorescent sensor array based on three kinds of different CDs exhibited diverse fluorescence patterns for each hydroxybenzaldehyde and nitrobenzaldehyde isomer, which were further analyzed by principal component analysis (PCA).