Receptors and spacers for a fluorescence-based lead ion chemosensor

1. A chemosensor device, comprising:

a compound of formula (I), or a salt thereof,

R 1 —CH 2 NH-G  (I)

wherein

R 1 is thiazole optionally substituted with R A or —(X—R 2 );

X at each occurrence is independently a single bond, CH 2 , O, S, NH, or N(CH 3 );

R 2 at each occurrence is independently a 5- to 12-membered cyclic group optionally having at least one double bond between two adjacent ring atoms, wherein R 2 optionally has at least one ring atom being N, O, or S, and wherein R 2 is optionally substituted with 1, 2, 3, or 4 R B ;

R A and R B at each occurrence is independently selected from the group consisting of —CH 3 , —CH 2 CH 3 , —CH 2 OH, —CH 2 NH 2 , —COCH 3 , —COOH, —CONH 2 , —CN, —OH, —OCH 3 , —NH 2 , —NHCH 3 , —N(CH 3 ) 2 , —SH, —SCH 3 , halogen, and halomethyl;

G is a cyclic fluorophore, wherein G is attached to R 1 —CH 2 NH through a ring atom, and wherein G is optionally substituted with -L-T;

L is a linker selected from the group consisting of a single bond, C 1-4 alkylene, OC 1-4 alkylene, NHC 1-4 alkylene, SO 2 C 1-4 alkylene, and C 1-4 alkyleneC 6 H 4 ,

T is selected from the group consisting of a leaving group, —OH, —NH 2 , —C(O)OH, protected hydroxyl, protected amino, and protected carboxyl,

an optical detector,

a light source, and

a receptacle adapted to contact an aqueous sample.

2. The chemosensor device of claim 1 , wherein the device is connected to a single or multiple chemical process units.

3. A machine comprising a chemosensor device of claim 1 , wherein the machine is a water desalinator, a water softener, a water purifier, a water tester, a fuel tester, a coffee maker, a washing machine, an ice maker, a boiler, or a blood tester.

4. The chemosensor device of claim 1 , wherein R 2 is an optionally substituted aryl, an optionally substituted heteroaryl, or an optionally substituted heterocycle having at least one double bond between two adjacent ring atoms.

5. The chemosensor device of claim 1 , wherein the compound has a structure of formula (I-a)

6. The chemosensor device of claim 5 , wherein X is a single bond.

7. The chemosensor compound of claim 5 , or a salt thereof, wherein R 2 is

8. The chemosensor device of claim 1 , wherein the compound has a structure formula (I-b)

9. The chemosensor device of claim 8 , wherein R A is —N(CH 3 ) 2 .

10. The chemosensor device of claim 1 , wherein G is anthracene, benzene, carbazole, diphenylfurane, naphthalene, 1,8-naphthalimide, porphyrin, or pyrene; and wherein G is optionally substituted with -L-T.

11. The chemosensor device of claim 1 , wherein G is 1,8-naphthalimide optionally substituted with -L-T.

12. The chemosensor device of claim 1 , wherein G is

which is optionally substituted with one or more -L-T.

13. The chemosensor device of claim 1 , wherein -L-T is

14. The chemosensor device of claim 1 , wherein the compound is selected from the group consisting of:

or salt thereof.

15. A method of detecting an ion in an aqueous sample, comprising:

contacting the aqueous sample with a chemosensor device of claim 1 ;

exposing the aqueous sample to light, whereupon the compound of the chemosensor device binds to the ion, thereby causing the compound to produce a fluorescence signal; and

detecting the fluorescence signal.

16. The method of claim 15 , wherein the aqueous sample is obtained from a water desalinator, a water softener, a water purifier, a water tester, a fuel teste, a coffee maker, a washing machine, an ice maker, a boiler, or a blood tester.

17. The method of claim 15 , wherein the chemosensor device is connected to a single or multiple chemical process units, and wherein the method is conducted in a continuous manner.

18. The method of claim 15 , wherein the ion is Pb 2+ , Ca 2+ , K + , Na + , Cr 3+ , Hg 2+ , Cd 2+ , Mg 2+ , As 3+ , As 5+ , or a combination thereof.