Luminescent Conductive Columnar π-Gelators for Fe(II) Sensing and Bio-Imaging Applications

Abstract

The high demand and scarcity of luminescent, photoconductive, and transparent gels necessitate its finding as they are potential components in photonic devices such as solar cell concentrators where optical losses via scattering and reabsorption require to be minimized. In this direction, we have reported highly transparent, blue luminescent as well as photoconductive gels exhibiting the hole mobility of 10 −3 cm 2 /V s at ambient temperature as investigated by the time-of-flight technique. The π-driven self-standing supergels were formed using triazole-modified phenylene-vinylene derivatives as gelators in a nonpolar solvent. Different microscopic studies revealed its entangled network of interwoven fibrilar self-assembly and anisotropic order in the gel state. Supramolecular assembly of xerogels, studied by small-and wide-angle Xray scattering (SAXS/WAXS) suggesting their local columnar hexagonal (Col h ) superstructure, is beneficial for conducting gels. Rheological measurements direct the stiffness and robustness of the organogels. In addition, the gelators were developed as a sensing platform for the ultrasensitive detection of Fe(II) ions at ppb level. 1 H nuclear magnetic resonance (NMR) titrimetric studies revealed that the interaction of the H-atom of triazole units with Fe(II) is responsible for quenching of blue fluorescence. Also, one of the gelators was successfully applied in bio-imaging using the pollen grains of the Hibiscus rosa-sinensis plant.

Ambipolar Charge Transport Properties of Naphthophenanthridine Discotic Liquid Crystals

“…The coating process of PVK allows us to obtain a thickness around 50 to 100 nm, which is almost less than 1% of the thickness of the LC cell. The PVK layer is used only as an absorbing layer for laser radiation to produce charge carriers that could propagate across the liquid crystal material . The thickness of the cell was maintained to be 20 μm by placing spacers between the top and bottom indium tin oxide/glass plates.…”

“…The hole and electron mobilities were examined by applying the voltage of ±50 to ±80 V using a Keithley 6487 picoammeter/voltage source. Hence, a maximum applied electric force across the cell would be 4 V μm –1 which is suitable for the ToF measurements without degrading the sample . A part of this field is used in overcoming the surface binding energy, and the rest is used to obtain an acceleration by the charge carriers.…”

“…The PVK layer is used only as an absorbing layer for laser radiation to produce charge carriers that could propagate across the liquid crystal material. 68 The thickness of the cell was maintained to be 20 μm by placing spacers between the top and bottom indium tin oxide/glass plates.…”

“…Hence, a maximum applied electric force across the cell would be 4 V μm −1 which is suitable for the ToF measurements without degrading the sample. 68 A part of this field is used in overcoming the surface binding energy, and the rest is used to obtain an acceleration by the charge carriers. The induced charge displacement was evaluated via dispersive transient photocurrent curves recorded using a digital oscilloscope (Keysight, DSOX3022T) connected to a voltage amplifier (Stanford Research SR560).…”

Discs to a ‘Bright’ Future: Exploring Discotic Liquid Crystals in Organic Light Emitting Diodes in the Era of New‐Age Smart Materials

“…The hole mobility value of the material was also commendable at 10 À 3 cm 2 /Vs as measured by the time-of-flight technique. [81]…”