Hybrid Copper Iodide Cluster-Based Pellet Sensor for Highly Selective Optical Detection of o‑Nitrophenol and Tetracycline Hydrochloride in Aqueous Solution

o-Nitrophenol (o-NP) and tetracycline hydrochloride (TCH)
residues
in various aquatic environments are two environmental contaminants,
which are seriously dangerous to both social safety and the environment.
Detection of such species in a water system with one optical sensor
is coveted for outdoor operation but has not been reported. Herein,
we report the function synergistic strategy for the construction of
a stable and luminescent hybrid copper­(I) iodine cluster-based sensor
[Cu4I4(ETBT)4] (UJN-Cu2, ETBT = 2-ethylbenzo­[d]­thiazole). A custom-designed detecting cell
for a solid sensor is used to detect the two types of contaminations.
The pressed pellet of UJN-Cu2 is capable of photoluminescence
distinguishing o-NP from its two isomers p-NP and m-NP, as well as
TCH from commonly used antibiotics in aqueous solutions. Importantly, UJN-Cu2 represents the first bifunctional luminescence sensor
for highly selective and sensitive detection of o-NP and TCH with
a limit of detection (LOD) of 2.30 and 4.15 μM, respectively.
Theoretical calculations and experimental results indicate that the
charge transfer between Cu and ETBT is responsible for the excitation
spectrum centered at 394 nm, which has a superior overlap with the
absorptions of o-NP and TCH. The UJN-Cu2 pellet optical
sensor has obvious advantages including being extremely easy to carry
and use, dual-detection ability, and excellent recyclability and sensitivity,
which make it is suitable for a long-time in-field outdoor detection
application. The present work not only develops the first dual-detection
optical sensor for nitroaromatics and antibiotics but also unveils
the feasibility of the hybrid copper­(I) iodine cluster as a solid
sensor in hunting environmental pollutants.