Chromogenic Properties of p-Pyridinium- and p-Viologen-Calixarenes and Their Cation-Sensing Abilities

Employing polyaniline/viologen complementarity to enhance coloration and charge dissipation in multicolor electrochromic display with wide modulation range

Multicolor electrochromic devices have gained attention widely. To support the development of multicolor electrochromic devices, we studied complementary combinations of a multicolor switchable polyaniline (PANI) electrode and 1-methyl-4,4'-bipyridyl iodide (MBI). In particular, MBI acting as an electrolyte and cathodic electrochromic layer can not only simplify the architecture of a device, but also support the color richness of the device simultaneously. Wide band optical modulation in visible light (58.1% at 550 nm) and near-infrared light (35% at 800 nm) confirms the advantageous optical properties of the combination, possessing a wide color gamut range over a range of working voltages adjustable for red, yellow, green, blue, and purple, each having a high color contrast of up to 73.8. This is accompanied by the excellent electrochemical performances of the mentioned combination, such as a fast response time of 1 s/1.9 s (modulating 77%-colored/bleached) with good cycle stability, and high coloration efficiency of 140.63 cm2/C. In addition, utilizing a screen-printed polyvinyl alcohol (PVA) as a masking barrier layer, it is possible to display patterned anti-counterfeit information within the application. Given these electrochromic performance properties, it is considered a readily feasible strategy to utilize PANI and MBI combination to develop novel electrochromic devices, which can be used widely in the areas of smart packaging, smart labels, and flexible smart windows associated with specific application scenarios.

A highly selective and sensitive fluorescence probe for dopamine determination based on a bisquinoline-substituted calix[4]arene carboxylic acid derivative

Dopamine (DA) at normal levels in the human body exhibits a high potential for maintaining a proper neuron network. However, their abnormalities in humans can bring out aggressive disorders such as Schizophrenia, hypertension, Tourette's syndrome, Alzheimer's disease, bipolar depression, Parkinson's disease, drug addiction and attention-deficit hyperactivity diseases. Hence, in this study, a bis-quinoline-substituted calix[4] arene carboxylic acid derivative (Quin-Calix-CO2H) at cone conformation was developed as an effective fluorescent sensor for the detection of a catecholamine neurotransmitter (dopamine). The structure of Quin-Calix-CO2H was confirmed using 1H-NMR, 13C-NMR, ESI-MS and elemental analysis techniques. The calixarene-based fluorescent sensor (Quin-Calix-CO2H) has shown fluorescence emission at 404 nm under the excitation of 270 nm. Further, biomolecules binding property of Quin-Calix-CO2H against various biomolecules such as L-cysteine (L-Cys), α-D-glucose (D-Glu), (+)-sodium-L-ascorbate (SAA), urea (UR), L-alanine (L-Ala) and dopamine (DA) exhibited that the fluorescent sensor enables selectively and sensitively detection for DA with a remarkable affinity. The probe Quin-Calix-CO2H has shown fluorescence quenching towards DA concentration ranging from 0 to 4.0 µM with a very low limit of detection (LOD) of 88.5 nmol L-1. In addition, the binding constant and stoichiometry as well as the mechanism of quenching have been also determined from the fluorescence data.Communicated by Ramaswamy H. Sarma.