Thiourea linked peracetylated glucopyranosyl–anthraquinone conjugate as reversible ON–OFF receptor for fluoride in acetonitrile

Supramolecular Logic Gates Based on the Conjugates of Calixarenes and Carbohydrates

In the era of application-oriented research, laboratory to real life translation is highly regarded and in great demand. This could mean that molecular science developed for sensing and detecting a variety of chemical species awaits conversion to devices. In that, the molecular logic gates are the most promising ones where the information storage and/or data processing can be easily carried out in terms of molecular inputs and electrical response outputs. This would facilitate the simultaneous execution of a diverse array of molecular sensing functions. The recent progress in molecular logic gates based on supramolecular optical receptors, in particular, fluorescent ones, such as calixarene derivatives and carbohydrate conjugates will have a transformative impact on molecular devices and will encourage this science to yield technology. Therefore, this review provides a critical evaluation of recent publications on molecular logic gates based on the derivatives of calixarenes and glyco-conjugates, including several from our own research group, with the view that the corresponding applications are a beneficiary in laboratory-to-device translation. In addition, this review is also expected to assist young researchers in planning their research focus in the broad area of supramolecular-based logic gates targeting some specific applications.

Allosteric binding properties of a 1,3-alternate thiacalix[4]arene-based receptor having phenylthiourea and 2-pyridylmethyl moieties on opposite faces

Thiacalix[4]arene receptors with two thiourea moieties and two 2-pyridyl moieties exhibited a heteroditopic dinuclear receptor with F− and Ag+ ions by a positive allosteric effect.

Combined TDDFT and AIM Insights into Photoinduced Excited State Intramolecular Proton Transfer (ESIPT) Mechanism in Hydroxyl- and Amino-Anthraquinone Solution

Time-dependent density functional theory (TDDFT) and atoms in molecules (AIM) theory are combined to study the photoinduced excited state intramolecular proton transfer (ESIPT) dynamics for eight anthraquinones (AQs) derivatives in solution. The calculated absorption and emission spectra are consistent with the available experimental data, verifying the suitability of the theory selected. The systems with the excited-state exothermic proton transfer, such as 1-HAQ, 1,5-DHAQ and TFAQ, emit completely from transfer structure (T), while the reactions for those without ESIPT including 1,4-DHAQ and AAAQ appear to be endothermic. Three reaction properties of three systems (1,8-DHAQ, DCAQ and CAAQ) are between the exothermic and endothermic, sensitive to the solvent. Energy scanning shows that 1,4-DHAQ and AAAQ exhibit the higher ESIPT energy barriers compared to 1-HAQ, 1,5-DHAQ and TFAQ with the "barrierless" ESIPT process. The ESIPT process is facilitated by the strengthening of hydrogen bonds in excited state. With AIM theory, it is observed that the change in electrons density ρ(r) and potential energy density V(r) at BCP position between ground state and excited state are crucial factors to quantitatively elucidate the ESIPT.

A naphthalene benzimidazole-based chemosensor for the colorimetric and on-off fluorescent detection of fluoride ion

A novel naphthalene benzimidazole (NBI)-based chemosensor (D2) was developed for fluoride ion (F^-) detection. The absorption spectrum of D2 changed dramatically from yellow to blue in the visible region accompanied with a 225nm red shift of its absorption maximum upon the addition of F^- in DMSO. D2 also exhibited a fluorescence turn-off response towards the fluoride ion. The emission intensity of D2 decreased drastically along the increasing F^- concentration and the detection limit for F^- was as low as 3.2×10^-9mol/L. ¹H NMR and HRMS-ESI results indicated that the formation of NBI-O^- through the desilylation reaction of F^- with NBI-OSi was responsible for the spectral changes. Overall, this kind of NBI-type molecules represent a new type chemosensor for the spectral detection of fluoride ion in solution.

A study of anion binding behaviour of 1,3-alternate thiacalix[4]arene-based receptors bearing urea moieties

Thiacalix[4]arene receptors with two urea moieties exhibited a high affinity towards all of the selected anions.

Synthesis and biological evaluation of new spirooxindoles with embedded pharmacophores

The newly synthesized spirooxindole derivatives have shownin vitroantioxidant, antidiabetic and acetylcholinesterase inhibitory activities.

A recyclable, fluorescent, and colorimetric sensor for fluoride anion in water using a crosslinked polymer functionalized with hydroxyl quinolinium

A crosslinked polymer-based recyclable, fluorescent, and colorimetric sensor for F⁻ in water.

Positive and negative allosteric effects of thiacalix[4]arene-based receptors having urea and crown-ether moieties

Allosteric binding behaviors of heteroditopic receptors bearing the 1,3-alternate conformation based thiacalix[4]arene have been evaluated by absorption and ¹H NMR titration experiments.

A highly selective colorimetric and “Off–On” fluorescent chemosensor for fluoride ions and its application as a molecular-scale logic device

A new sensor based on phenolic hydroxy and imine groups was used as an efficient colorimetric and “turn on” fluorescent sensor, which exhibited high selectivity and sensitivity for F⁻.

Design, synthesis and characterization of indole based anion sensing receptors

The fluoride binding ability of indole based receptors was found to depend on the electron deficiency of the acceptor unit and enhanced H-bond donating character of the indole N–H group.

A fluoride-driven ionic gate based on a 4-aminophenylboronic acid-functionalized asymmetric single nanochannel

Fluorine is one of the human body's required trace elements. Imbalanced fluoride levels severely affect the normal functioning of living organisms. In this article, an anion-regulated synthetic nanochannel is described. A fluoride-driven ionic gate was developed by immobilizing a fluoride-responsive functional molecule, 4-aminophenylboronic acid, onto a single conical polyimide nanochannel. When the ionic gate was in the presence of fluoride, the boron bound F-, and the hybridization of the boron center changed from sp2 to sp3. Thus, negatively charged monofluoride adduct (RB(OH)2F-), difluoride adduct (RB(OH)F2-), and trifluoride adduct (RBF3-) modified surfaces with different wettability would be formed successively by increasing the concentration of F-. On the basis of the variation of surface charge and wettability, the nanochannel can actualize reversible switching between the "off" state and the "on" state in the absence and presence of F-, respectively. As an anion-regulated synthetic nanochannel, this fluoride-driven ionic gate was characterized by measuring ionic current, which possesses high sensitivity, fine selectivity, and strong stability. Thus, this gate may show great promise for use in biosensors, water quality monitoring, and drug delivery.