Traditional (1D, 2D, and 3D) codes are widely used to provide convenient readouts of encoded information. However, manipulating and transforming the encoded information is typically difficult to achieve. Here, the preparation of three fluorescent (blue, green, and red) hydrogels containing both tetracationic receptor-anion recognition motifs and gel-specific fluorophores is reported, which may be used as building blocks to construct through physical adhesion fluorescent color 3D codes (Code A, Code B, and Code C) that may be read out by a smartphone. As a result, parts of the individual gel components that make up Code B can be replaced with other gel building blocks to form Code A via a cut and adhesion approach. A fluorophore responsive to ammonia is further incorporated into one of the hydrogels. This allows the gel block-derived pattern that makes up Code C to be converted to Code A by chemical means. Therefore, the encoded information produced by patterns of the present hydrogels may be transformed through either physical action or by exposure to a chemical stimulus. Due to the nature of the soft materials involved, the codes can be used as wearable materials.

No abstract

We report here the fluorescent sensing of both aromatic and linear saturated dicarboxylate anions (DC2– ) (as their tetrabutylammonium salts) with different lengths and shapes in acetonitrile using a single fluorescent probe, i.e., the bis-calix[4]­pyrrole-appended 9,14-diphenyl-9,14-dihydrodibenzo­[a,c]­phenazine (DPAC-bisC4P) incorporating a vibration-induced emission (VIE) phenazine core. Fluorescence titration studies revealed that treating DPAC-bisC4P with dicarboxylate guests capable of forming pseudomacrocyclic host–guest complexes via multiple hydrogen-bonding interactions between the dicarboxylates and calix[4]­pyrrole moieties led to a blue-shift in the emission of the phenazine core. The binding-based fluorescence-tuning features of DPAC-bisC4P allow the underlying binding events and inferred structural changes to be monitored in the form of different chromaticity outputs. The analyte-induced differences in the fluorescence response to DC2– cover a wide range within the chromaticity diagram and can be visualized readily. The present system thus functions as a rudimentary dicarboxylate anion sensor. It highlights the potential benefits associated with combining a tunable VIE core with noncovalent binding interactions and thus sets the stage for the development of new fluorescent chemosensors where a single chemical entity responds to different analytes with a high level of tunability.

Reported here is a hydrogel-forming polymer network that contains a water-soluble tetracationic macrocycle. Upon immersion of this polymer network in aqueous solutions containing various inorganic and organic salts, changes in the physical properties are observed that are consistent with absorption of the constituent anions into the polymer network. This absorption is ascribed to host-guest interactions involving the tetracationic macrocyclic receptor. Removal of the anions may then be achieved by lifting the resulting hydrogels out of the aqueous phase. Treating the anion-containing hydrogels with dilute HCl leads to the protonation-induced release of the bound anions. This allows the hydrogels to be recycled for reuse. The present polymer network thus provides a potentially attractive approach to removing undesired anions from aqueous environments.

Metallo-supramolecular chemistry based on the reversible, directional and predictable noncovalent interaction of metal-ligand coordination has been widely applied in constructing a myriad of two-dimensional and three-dimensional supramolecules with sophisticated structures. The development of metallosupramolecular chemistry highly relies on facile characterization methods. In the further advancement of structural complexity with desired functions, however, conventional crystallographic and spectroscopic characterizations were limited by crystal growth, sample purity and severe signal overlaps. With high sensitivity and low requirement for purity, multidimensional mass spectrometry (MS) including electrospray ionizationmass spectrometry (ESI-MS), tandem mass spectrometry (MS2), and ion mobility-mass spectrometry (IM-MS),