3-Diethylaminophenol is considered a hazardous substance due to its potential to cause irritation to the skin, eyes, and respiratory system. Here we will introduce the synthesis method of this substance, its applications in sensors, and its environmental hazards.

Sensing of a Nerve Agent Simulant and an Aminophenol

The metal–organic framework (MOF) Hf-DUT-52 was prepared with diamino functionality by the solvothermal method. This material displayed fluorometric sensing ability toward a nerve agent simulant (diethyl chlorophosphate (DCP)) and 3-diethylaminophenol (3-DEAP). It is the first-ever reported fluorescent MOF sensor for DCP and 3-DEAP. Apart from a fast response (<5 s), the sensor had a very low detection limit for both DCP and DEAP (limit of detection (LOD) values for DCP and 3-Diethylaminophenol sensing were 9 and 125 nM, respectively). The obtained detection limit is the second lowest among all of the reported optical sensors for DCP. The sensor also displayed its capability to identify the presence of trace amount of DCP in various natural water specimens with good selectivity. APs are mainly used as analgesics and antipyretic drugs to alleviate pain and fever. But excessive intake of different APs as a drug can cause nephrotoxicity and hepatotoxicity. APs such as 3-diethylaminophenol (3-DEAP) are used as a fluorescent whitening agent to prepare various dyes and printing inks and as a stabilizer of chlorine-containing thermoplastics. However, due to the two-dimensional (2D) nature of the sensor, it suffered from high detection limits and response time. On the other hand, our probe could detect the presence of DCP and 3-diethylaminophenol down to 9 and 125 nM concentration levels, respectively. For DCP sensing, our sensor is the first-ever report with a three-dimensional (3D) MOF, and the sensitivity of our probe is comparable with the most sensitive sensor reported by Sahoo et al.[1]

Motivated by the luminescence property, excellent physicochemical stability, and considerable surface area of the hafnium MOF, a novel fluorescence sensor for DCP and 3-DEAP has been developed in this work. The sensor was prepared using a straightforward solvothermal process, and the obtained new MOF was characterized by a variety of analytical methods. The presented MOF is the best sensor for DCP detection based on the response time (5 s), and it is the second best with respect to LOD value (10.6 nM) among reported optical sensors. It is also the first-ever reported MOF sensor for both DCP and 3-diethylaminophenol. The sensor provided good selectivity toward DCP and 3-diethylaminophenol, even in the presence of various competitors. We could demonstrate the ability of DCP recognition of the sensor in various real water specimens. Facile fabrication of an inexpensive, portable MOF@cotton composite and a MOF@PVA thin film was accomplished.

The applicability of the MOF@cotton composite for DCP and 3-diethylaminophenol sensing in the liquid phase (up to the nanomolar level) was demonstrated. Furthermore, the DCP sensing ability of the MOF@PVA thin film in the vapor phase was established. The formation of a complex between the free ?NH2 groups of the sensor and the DCP molecules is the plausible reason behind the quenching process for DCP. The FRET and photoinduced electron transfer (PET) processes are presumably responsible for 3-diethylaminophenol sensing. DFT calculations highlighted the role of linker defects in the Hf(IV) MOF, resulting in accessible Hf sites with sensing ability for DCP and 3-diethylaminophenol.

3-Diethylaminophenol appended pyrimidine bis hydrazone for the sequential detection of Al3+ and PPi ions

Scientists have reported the multi-functional feature of 3-diethylaminophenol appended pyrimidine bis hydrazone. Herein, we have synthesized utilized the pyrimidine based 3-diethylaminophenol functionalized probe (HD), which could act as a simple yet effectual fluorescent sensor for the sequential detection of Al3+ and PPi ions. The probe exhibits off–on-off fluorescent characteristics towards Al3+ and PPi ions in DMF-Tris HCl buffer solution (7:3 v/v, pH 7.4). The fluorimetric recognition of Al3+ ions displayed noticeable enhancement in the emission intensity with high association constant and lower LOD values. The in-situ prepared HD-Al3+ ensemble exhibited turn-off fluorescence detection features towards PPi ions via demetallation approach. Besides, the sensing characteristics of the probe was utilized for constructing INHIBIT logic gate. The remarkable Al3+ sensing behavior was also employed for other relevant applications such as real water analysis and qualitative detection of Al3+ ions in tablet extracts.[2]

Inorder to study the potential applications of 3-diethylaminophenol functionalized probe, real water applications were performed. Tap water, distilled water and drinking water were collected from university department for performing real water sample analysis. Two different concentrations of Al3+ ions have been spiked into the three water samples and carried out the emission studies. The recovery percentage of the ions were calculated in the range of 98.50 to 100.75 which clearly demonstrate that the probe 3-diethylaminophenol functionalized probe can be undoubtedly utilized for detection of Al3+ ions in the real water samples. Similarly, the real water applications for the detection of PPi was executed. Here also, two different concentrations of PPi were spiked into the solution containing 3-diethylaminophenol functionalized probe with 10 equivalents of Al3+ ions and performed emission experiments. It is understood that good recovery percentage was obtained in the range of 95.5 to 101.17 which leads to the conclusion that the HD-Al3+ ensemble can be employed for the detection of PPi effectively.

In the present work, we have designed and developed 3-diethylaminophenol appended pyrimide bis hydrazone (HD) which acts as an excellent probe for the selective consecutive detection of Al3+ and PPi ions. Remarkable emission enhancement was exhibited by HD towards Al3+ ions with reasonably high association constant and lower L.O.D values. Further, in-situ prepared HD-Al3+ ensemble exhibited turn-off emission response with PPi ions among various other anions via demetallation approach. Overall sensing behavior of 3-diethylaminophenol functionalized probe was perfectly employed for the construction of INHIBIT logic-gate, real-water analysis, and qualitative determination of Al3+ ions in anatacid tablets.

Synthesis of 3-Diethylaminophenol

General procedure for the amination of resorcinol with secondary amine catalyzed by Raney Ni. Resorcinol (2.2 g, 20 mmol), secondary amine (30 mmol) and Raney Ni (110 mg) were added to water(50 ml) in a 100 ml autoclave. The autoclave was purged with hydrogen gas three times, then maintained 0.05 Mpa pressure. The mixture was heated to 200 °C rapidly. Then stirring was maintained for 3 h. The reaction mixture was cooled to room temperature, and then extracted with N-butyl acetate. The organic layer was dried (MgSO4), filtered and concentrated to give the crude product. The pure product 3-Diethylaminophenol was got through flash column chromatography on silica gel (petroleum ether/acetyl acetic ester (3/1, v/v)).[3]

References

[1]Ghosh S, Lipin R, Ngoipala A, Ruser N, Venturi DM, Rana A, Vandichel M, Biswas S. Hf-Based MOF for Rapid and Selective Sensing of a Nerve Agent Simulant and an Aminophenol: Insights from Experiments and Theory. Inorg Chem. 2023 Sep 11;62(36):14632-14646.

[2]Anitha O, Thiruppathiraja T, Lakshmipathi S, Murugesapandian B. Diethylaminophenol appended pyrimidine bis hydrazone for the sequential detection of Al3+ and PPi ions. Spectrochim Acta A Mol Biomol Spectrosc. 2023 Dec 5;302:123077.

[3]Ge, Xin; Pan, Jiong-Bin; Qian, Chao; Feng, Lie; Chen, Yun-Bin; Chen, Xin-Zhi[Catalysis Communications, 2014, vol. 46, p. 201 - 207]