Smart Multiple Photoresponsive Tongue for Sensing Umami, Sour and Bitter Tastes Based on Tb³⁺ Functionalized Hydrogen‐Bonded Organic Frameworks

Abstract

Artificial tongues have attracted increasing attention for the perception abilities of five basic tastes. However, simple and versatile identification of different tastes is a formidable challenge for bionic taste sensor. Enriching photoluminescence mechanisms to improve possibilities of multiple optical responses is conducive to simplify the sensor array. Herein, a single sensor Tb@MCATMA (Tb@1) is developed displaying dual‐emissions of both green fluorescence and deep‐blue phosphorescence by ternary co‐assembly of Tb3+, trimesic acid (TMA) and a 2D hydrogen‐bonded organic framework of melamine and cyanuric acid, MCA HOF. This sensor is capable of imitating the human gustatory system to identify and discriminate umami (disodium 5′‐inosinate and disodium 5′‐guanylate), sour (citric acid and oxalic acid) and bitter (2‐furaldehyde and 5‐hydroxymethylfurfural) substances through the diverse photoresponsive modes. Upon excitation wavelength as additional variable, the sensor can further collect the individual “fingerprint information” of six analytes related to tastes and quantitatively detect them with high accuracy. Moreover, the sensing mechanism of each analyte is explored in detail and substantiate that the uniform photoresponsive modes elicited by distinct analytes stem from the shared sensing mechanism. This work provides a facile and powerful sensor platform for taste perception to develop artificial photoresponsive tongue applicable to bionic gustatory system.

Flexible hydrogen-bonded organic frameworks (HOFs): opportunities and challenges

“…Unlike MOFs and COFs, which are constructed through strong coordination or covalent bonds, the weaker bond strength and flexible feature of H-bonds lead to challenges in terms of stability and structural design of HOFs, but at the same time, bring new opportunities for structural diversity and flexibility. [10][11][12][13][14][15][16][17][18][19][20][21][22] In recent years, HOFs have shown great potential in gas storage/separation, sensing, proton conduction, etc.…”