Emission Color Tuning and White Light Generation from a Trimolecular Cocktail in Cationic Micellar System with Promising Applicability in the Anticounterfeiting Technology

Abstract

The development of photoluminescent (PL) systems, displaying multiple stimuli-responsive emission color tuning, has been the pressing priority in the recent times due to their huge role in contemporary lighting and anticounterfeiting technologies. Acknowledging this importance, we present a simple and eco-friendly PL system showing emission color tuning in response to different stimuli, that is, the composition of the system, pH, excitation wavelength, and the temperature with the plus point of getting significantly pure white light emission (WLE). The novel system is fabricated from the aqueous mixture of three organic fluorophores, umbelliferone (UMB), fluorescein (FLU), and Rhodamine-B (RB). By varying the fluorophore composition in the mixture at pH 12, nearly pure WLE with a Commission Internationale d'Eclairage (CIE) 1931 profile of (0.33, 0.33) was obtained at the excitation wavelength of 365 nm, the sustainability of which was ensured by employing the micellar self-assemblies of tetradecyltrimethylammonium bromide (TTAB) molecules. Similar WLE was obtained under mildly acidic conditions (pH 6) but at the excitation wavelength of 330 nm. By proper tuning of pH and the wavelengths of the system to use it as a fluorescent ink, we found a remarkable and highly applicable phenomenon observed for the first time, that is, triple-mode orthogonal emission color tuning with white light ON/OFF switching. We validate the vital applicability of this phenomenon in protecting the authenticity of the document with its hard-to-counterfeit property. The applicability of this phenomenon is also explored by synthesizing PVA-based fluorescent films from the tri-fluorophore mixture. Moreover, the emission color of the PL system was explored lucidly for its temperature dependence owing to the thermal responsiveness of RB emission, where the PL system proves to be a full-color RGB system.

Controllable Aggregation-Induced Emission and Förster Resonance Energy Transfer Behaviors of Bistable [c2] Daisy Chain Rotaxanes for White-Light Emission and Temperature-Sensing Applications

“… a Measured in THF/H 2 O solvent (at f w = 60%). b Obtained from DLS results. c Determined from TRPL profiles at λ ex = 365 nm and λ em = 405 nm. d Calculated from the equation: E F R E T = 1 − τ D A τ D . e Energy transfer efficiency ( E ET ) of Mixture : E = 5% (without FRET process). f Energy transfer efficiencies ( E ET ) of M and [ c 2 ]A : combined energy transfers of PET and FRET. g Calculated from the equation: Φ s = Φ r ( A r F s / A s F r )( n s 2 / n r 2 ). …”

“…Fluorescence quantum yields (Φ) were obtained using the following equation: Φ s = Φ r false( italicA normalr italicF normals / italicA normals italicF normalr false) false( italicn normals 2 / italicn normalr 2 false) …”

“…The construction of color-tunable luminescent materials, especially white-light emissions, receives significant attraction owing to their extensive applications, such as temperature sensing, biological imaging, lighting, and anticounterfeiting. − In particular, to obtain white-light-emitting (WLE) materials, the general ways have focused on the integration of RGB colored (red-green-blue) or two complementary-colored photogenic dyes . By integrated strategies, WLE materials have been attained by fine-tuning small organic molecular structures, polymerizations, supramolecular chemistry, nanotechnologies, and multicomponent gelations. − Especially, supramolecular assemblies that provide favorable approaches due to the optical outputs can be well adjusted by altering the noncovalent interactions, such as host–guest complexations, aggregations, hydrogen bondings, coordinative bonds, and electrostatic interactions. − By these merits, we envision that novel supramolecular-based bistable [ c 2] daisy chain rotaxanes containing emitters may offer a new strategy for the fabrication of tunable multiemissions, including white-light emissions.…”

Dual-Color Photoluminescent Functionalized Nanoparticles for Static-Dynamic Anticounterfeiting and Encryption: First Collaboration of Spiropyran and Coumarin

“…The development of high-security anticounterfeiting technologies based on photoluminescent, photochromic, and hydrochromic materials is a significant research area in recent years and has showed rapid growth for reported intelligent systems such as stimuli-responsive inks, labels, and security tags. − In today’s world, governments, companies, and customers look for the most efficient anticounterfeiting technology with high security, intelligent and multi-level authentication, and complex or high-tech formulation to increase the security of confidential documents such as banknotes, passports, national cards, certificates, and valuable products (drugs, vaccines, chemicals, and other materials or instruments related to human health). ,− The encryption and encoding of information as security tags such as quick responsive (QR) codes and barcodes is a significant solution to overcome counterfeiting and copying of confidential and security documents. However, scientists are interested in developing a new category of anticounterfeiting materials for the printing of security tags with multi-level security and a complex authentication process.…”