Method of detecting mercury ions with a fluorescein hydrazide-appended metal-organic framework as a chemosensor

Patent metadata

Field	Value
Publication number	US-12135281-B2
Application number	US-202217840045-A
Country	US
Kind code	B2
Filing date	Jun 14, 2022
Priority date	Jun 14, 2022
Publication date	Nov 5, 2024
Grant date	Nov 5, 2024

Abstract

A method of detecting Hg 2+ ions in an aqueous solution is described. The method includes contacting the aqueous solution with a metal-organic framework (MOF) chemosensor composite to form a mixture and monitoring a change in an absorption and/or a fluorescence profile of the MOF chemosensor composite in the mixture to determine a presence or absence of Hg 2+ ions in the aqueous solution. The MOF chemosensor composite includes fluorescein hydrazide (FH); and a MOF, including nickel as a metal ion and at least one trimesic acid (BTC) ligand. A hydrazide group on the fluorescein hydrazide coordinates to the metal ion of the MOF.

First claim

The invention claimed is:

1. A method of detecting Hg 2+ ions in an aqueous solution, comprising:
contacting the aqueous solution with a metal-organic framework (MOF) chemosensor composite to form a mixture; and
monitoring a change in an absorption and/or a fluorescence profile of the MOF chemosensor composite in the mixture to determine a presence or absence of Hg 2+ ions in the aqueous solution;
wherein the MOF chemosensor composite, comprises:
fluorescein hydrazide (FH); and
a MOF, comprising:
nickel as a metal ion; and
at least one trimesic acid (BTC) ligand;

wherein a hydrazide group on the FH coordinates to the metal ion of the MOF.

2. The method of claim 1 , wherein a unit of the MOF chemosensor composite has a formula of [Ni 3 (BTC) 2 (H 2 O) 3−n (FH) n ] wherein n=1, 2 or 3.

3. The method of claim 1 , wherein at least 90% of the nickel is Ni 2+ .

4. The method of claim 1 , wherein the MOF chemosensor composite has a morphology of rod-shaped structures assembled into sheets.

5. The method of claim 1 , wherein the MOF chemosensor composite has a Brunauer-Emmett-Teller (BET) specific surface area of 350-450 m 2 g −1 .

6. The method of claim 1 , wherein the MOF chemosensor composite has a stability up to 150° C.

7. The method of claim 1 , wherein the MOF has at least one pore; and
wherein the fluorescein hydrazide at least partially penetrates at least one pore of the MOF.

8. The method of claim 1 , further comprising:
monitoring the change in the absorption profile of the MOF chemosensor composite between 350 and 600 nm;
wherein a peak of the profile between 350 and 380 nm decreases in intensity and a peak between 550 and 600 nm increases in intensity in the presence of Hg 2+ .

9. The method of claim 1 , further comprising:
monitoring the change in the fluorescence profile of the MOF chemosensor composite between 500 and 650 nm;
wherein a peak of the profile between 515 and 550 nm increases in intensity in the presence of Hg 2+ .

10. The method of claim 1 , wherein the change in the absorption and/or fluorescence profile linearly correlates with the concentration of Hg 2+ in the aqueous solution.

11. The method of claim 1 , further comprising quantifying the change in the absorption and/or fluorescence profile to determine a concentration of Hg 2+ ions in the aqueous solution.

12. The method of claim 1 , wherein the aqueous solution further comprises at least one metal cation selected from the group consisting of Na + , K + , Ca 2+ , Mg 2+ , Sr 2+ , Rb 2+ , Cs 2+ , Al 3+ , Ga 3+ , Fe 2+ , Fe 3+ , Cu 2+ , Ni 2+ , Pb 2+ , Cd 2+ , Co 2+ , Zn 2+ , Pd 2+ , and Ag + ; and
the change in the absorption and/or fluorescence profile occurs only in the presence of Hg 2+ .

13. The method of claim 1 , wherein the MOF chemosensor composite is selective for detecting Hg 2+ ions.

14. The method of claim 1 , wherein the limit of detection for Hg 2+ ions is 1-10 ppb.

15. The method of claim 1 , wherein the binding constant of the Hg 2+ to the MOF chemosensor composite is 10 5 -10 6 M −1 .

16. The method of claim 1 , further comprising:
adding ethylenediaminetetraacetic acid to the mixture to form a solution;
filtering the solution and drying at a temperature of 80-120° C. for at least one hour to form a recovered MOF chemosensor composite.

17. The method of claim 16 , wherein the recovered MOF chemosensor composite maintains at least 90% of the crystallinity of the MOF chemosensor composite.

Assignees

• Univ King Fahd Pet & Minerals

Inventors

• Helal Aasif
• Naeem Muhammed
• Fettouhi Mohammed
• Zahir Md Hasan

Classifications

• G01N2021/174

  either absorption-reflection or emission-fluorescence · CPC title

• G01N33/1813

  Specific cations in water, e.g. heavy metals · CPC title

• G01N21/78

  producing a change of colour · CPC title

• G01N2021/7786

  Fluorescence · CPC title

• G01N21/3577 Primary

  for analysing liquids, e.g. polluted water · CPC title