Efficient and Rapid Synthesis of a Solvent and Ion-Responsive Luminescent Copper 2-Aminoterephthalate Thin Film

Abstract

Metal–organic coordination polymers are promising optical sensing materials due to their tunable physical and chemical properties, which can be controlled through careful selection of metal centers, organic linkers, and/or reaction conditions. The fabrication of coordination polymers in thin film form is particularly desirable for sensor development because it facilitates integration with sensing platforms such as optical fibers, enables sensing material recovery and regeneration, and can enhance analyte uptake during analysis. However, many thin film fabrication techniques are tedious and require high temperatures and/or expensive equipment, creating a significant barrier toward scalable production. Here, coordination polymer thin films comprised of copper and 2-aminoterepthalic acid are selectively grown within 30 min at room temperature and under ambient atmosphere using an aluminum-doped zinc oxide template, circumventing the long time and high equipment costs typically associated with thin film production. The films luminesce in the presence of polar protic solvents and exhibit enhanced emission in the presence of aluminum­(III) ions, an economically critical metal according to the 2022 United States Geological Survey. The “turn on” luminescent response to aluminum is selective against 15 other metal ions commonly found in environmental streams, and is highly sensitive, with estimated detection limits down to 120 parts-per-billion in water. As a proof-of-concept, the films were evaluated on diluted fly ash streams, with luminescent signals that qualitatively correlate with inductively coupled plasma mass-spectrometry analysis. Taken together, this work presents a promising route toward the scalable production of optically active coordination polymer films.

Zinc adeninate metal–organic framework-coated optical fibers for enhanced luminescence-based detection of rare earth elements

“…S1†). The lab-built fiber optic system 9,10 was initially tested on aqueous solutions of four visible-emitting REEs: terbium, europium, samarium, and dysprosium in solution and after drying the fiber-optic tip following REE exposure (Scheme 1). Characteristic emission peaks were observed from each of the REEs; this emission resulted from energy transfer from the immobilized BTC-1 MOF to the encapsulated REE cations, which are absorbed by the anionic MOF.…”

“…The patented portable fiber optic probe has been described elsewhere. 9 The custom-built system uses a mounted 275 nm light-emitting diode (LED, Thorlabs, M275L4, 45 mW) as the light source, and the UV light is focused using a Thorlabs LA4025 lens through a 240–395 nm bandpass filter (Thorlabs FGUV5M). This light then enters into the 9-fiber arm of a bifurcated solarization-resistant optical fiber cable (Thorlabs BF19Y2HS02, solarization-resistant 19–200 μm 0.22NA fiber bifurcated cable bundle).…”

“…2). 8,9 Briefly, the MOF-coated tip was affixed to the base of a solarization-resistant bifurcated fiber optic cable using a fiber terminator clamp; one branch of the cable ran from the fiber to a deep UV light-emitting diode (LED, 275 nm), and the other branch was connected to an Ocean Optics QE Pro spectrometer. The MOF structure was confirmed by X-ray diffraction (Fig.…”

“…7,8 Luminescence-based sensors offer an attractive alternative due to their low instrumentation costs, ease-ofuse, high sensitivity, and portability, facilitating transport into the field and between labs. [7][8][9][10][11] Moreover, REEs are a particularly suitable sensing target because, unlike other metals, several REEs are inherently luminescent: REE emission bands are narrow, element distinct and wellresolved from one another, enabling multiple metals to be detected and distinguished simultaneously. 2,12 However, the optical transitions that give rise to these emission bands are parity forbidden, rendering direct excitation inefficient.…”

Metal–organic framework thin films: review of their room-temperature synthesis and applications

“…An emerging room temperature fabrication method involves using templates for MOF film growth and patterning. [57][58][59][60] Crawford et al utilized conductive aluminum-doped zinc oxide (AZO) as a seed layer template for the rapid LBL growth of copper benzene-1,3,5-tricarboxylate (Cu-BTC) films at room temperature. The MOF film forms on the AZO layer through a hydroxyl complex salt (HDS) intermediate.…”