Double-Site Twisted D-π-D′ Conjugates with Versatile Photophysical Facets for Diverse Optical Applications and Wash-Free Bioimaging of Cancer Cells

Abstract

It is still a conundrum to design a single but simple organic molecule possessing numerous realistic photophysical properties such as mechanofluorochromism, aggregation-induced emission (AIE) properties, solvatochromic DSE-gens (dual-state emissive fluorogens), and viscofluorochromism. Unlike D-π-A, D-π-D′ systems are seldom explored with various applied features. This work finds how a single D-π-D′ indole-anthracene conjugate displays all these properties with real-world applications. Especially, an indole-anthracene-π-phenothiazine conjugate (IAP) appears as a solvatochromic (91 nm shift) DSE-gen that shows the longest 62 nm blueshifted enhanced emission on aggregation and the longest 45 nm blueshifted viscofluorochromic features. Furthermore, IAP adopts a fingertip-pressure-sensitive 35 nm blueshift, while a triphenylamine-linked analogue IAT demonstrates a 23 nm mechanofluorochromic redshift. Conformationally twisted backbone and π-conjugations are judiciously balanced to exhibit these optical features. Such diverse and contrasting photophysical facets are elucidated through experimental and detailed timedependent density functional theory investigations to meet rational understandings. These fluorophores are utilized as hidden patent fingerprint memory-based platforms and software-assisted comparison studies to identify counterfeiters. Furthermore, highly sensitive fingertip-aided mechanofluorochromic features are useful for inkless security writing. Besides, wash-free bioimaging of robust oral cancer cells (FaDu) could be accomplished satisfactorily in the green (IAT) and orange-red regions (IAP) with a lower probe concentration. The anticancer property of IAT enables visualization of the progressive distortion of the dying cancer cells during wash-free bioimaging.

Light Emitting Rare Earth Doped K3GdF6:Eu3+ for Spectral Mapping/Imaging Studies

“…For a considerable time, scientists have searched for luminescent materials demonstrating remarkable potency in different domains such as photonics, optoelectronics, optical information storage, bioimaging, etc. − In this pursuit, inorganic materials, spanning from nano to micrometer scales and infused with trivalent rare earth (RE 3+ ) ions, have emerged as highly promising candidates. − The lanthanide elements possess rich energy-level structures and intrinsic 4f n orbitals, which endow lanthanide-doped materials with exceptional luminescent properties and efficient spectral conversion capability via down-shifting and upconverting mechanisms. − The long luminescence lifetime, distinct emission bands, multicolor tunable luminescence, low toxicity, low photobleaching potential, and strong chemical stability make them ideal for real-life applications such as solid-state lasers, color displays, solar cells, luminescent biodetection, theranostics, etc. − The luminescence properties of rare earth elements are significantly affected by changes in size, phase transitions, coordination environment, and modifications in the geometry of the crystal system. , …”