Potassium fluoroionophore

A method for measuring potassium ion concentration in a fluid sample, comprising the steps of:

• (a) obtaining an optode comprising the fluoroionophore having the structure:
• wherein
• (i) R is selected from the group consisting, independently or in combination, of hydrogen, alkyl, alkenyl, alkynyl, alkoxy, ether, acyl, carboxylic acid, carboxylic ester, unsubstituted aryl substituted aryl, aryloxy, heteroaryl, and heteroaryloxy groups, wherein the heteroatom is selected from nitrogen and sulfur;
• (ii) W is —O(CH2)2O(CH2)2—;
• (iii) X is selected from the group consisting, independently or in combination, of nitrogen, saturated alkyl, unsaturated alkyl, unsubstituted aryl, and substituted aryl, wherein the aryl group may contain a heteroatom selected from the group consisting of nitrogen, sulfur and oxygen;
• (iv) Y is selected from the group consisting, independently or in combination, of saturated alkyl, unsaturated alkyl, unsubstituted aryl, substituted aryl, ether, carboxylic acid, carboxylic ester, secondary amine and sulfur;
• and
• (v) Z is a fluorophore, wherein a negative, thermo-neutral or slightly positive free energy value is obtained from the Rehm-Weller equation for the compound;
• (b) contacting the optode with a fluid sample suspected of containing potassium ions;
• and
• (c) measuring the fluorescence from the optode following the contacting of the optode with the fluid sample, wherein the fluorescence from the optode can be correlated with the activity of the potassium ions in the fluid sample.

A method for measuring potassium ion concentration in a cell of an organism, comprising the steps of:

• (a) introducing into the cell a fluoroionophore having the structure:
• wherein
• (i) R is selected from the group consisting, independently or in combination, of hydrogen, alkyl, alkenyl, alkynyl, alkoxy, ether, acyl, carboxylic acid, carboxylic ester, unsubstituted aryl substituted aryl, aryloxy, heteroaryl, and heteroaryloxy groups, wherein the heteroatom is selected from nitrogen and sulfur;
• (ii) W is —O(CH2)2O(CH2)2—;
• (iii) X is selected from the group consisting, independently or in combination, of nitrogen, saturated alkyl, unsaturated alkyl, unsubstituted aryl, and substituted aryl, wherein the aryl group may contain a heteroatom selected from the group consisting of nitrogen, sulfur and oxygen;
• (iv) Y is selected from the group consisting, independently or in combination, of saturated alkyl, unsaturated alkyl, unsubstituted aryl, substituted aryl, ether, carboxylic acid, carboxylic ester, secondary amine and sulfur;
• and
• (v) Z is a fluorophore, wherein a negative, thermo-neutral or slightly positive free energy value is obtained from the Rehm-Weller equation for the compound;
• and
• (b) measuring the fluorescence from the cell following the introduction of the fluoroionophore into the cell, wherein the fluorescence from the cell can be correlated with the activity of the potassium ions in the cell.

A method for measuring potassium ion activity in a fluid sample, comprising the steps of:

• (a) introducing into the fluid sample a fluoroionophore having the structure:
• wherein
• (i) R is selected from the group consisting, independently or in combination, of hydrogen, alkyl, alkenyl, alkynyl, alkoxy, ether, acyl, carboxylic acid, carboxylic ester, unsubstituted aryl substituted aryl, aryloxy, heteroaryl, and heteroaryloxy groups, wherein the heteroatom is selected from nitrogen and sulfur;
• (ii) W is —O(CH2)2O(CH2)2—;
• (iii) X is selected from the group consisting, independently or in combination, of nitrogen, saturated alkyl, unsaturated alkyl, unsubstituted aryl, and substituted aryl, wherein the aryl group may contain a heteroatom selected from the group consisting of nitrogen, sulfur and oxygen;
• (iv) Y is selected from the group consisting, independently or in combination, of saturated alkyl, unsaturated alkyl, unsubstituted aryl, substituted aryl, ether, carboxylic acid, carboxylic ester, secondary amine and sulfur;
• and
• (v) Z is a fluorophore, wherein a negative, thermo-neutral or slightly positive free energy value is obtained from the Rehm-Weller equation for the compound;
• and
• (b) measuring the fluorescence from the cell following the introduction of the fluoroionophore into the cell, wherein the fluorescence from the cell can be correlated with the activity of the potassium ions in the cell.

A sensor, consisting essentially of a carrier and an active layer applied to the carrier, wherein the active layer comprises a transparent support material in which a compound is situated, the compound having the structure:

• wherein
• (a) R is selected from the group consisting, independently or in combination, of hydrogen, alkyl, alkenyl, alkynyl, alkoxy, ether, acyl, carboxylic acid, carboxylic ester, unsubstituted aryl, substituted aryl, aryloxy, heteroaryl, and heteroaryloxy groups, wherein an aryl group may contain a heteroatom selected from the group consisting of nitrogen and sulfur;
• (b) W is —O(CH2)2O(CH2)2—;
• (c) X is selected from the group consisting, independently or in combination, of nitrogen, saturated alkyl, unsaturated alkyl, unsubstituted aryl, and substituted aryl, wherein an aryl group may contain a heteroatom selected from the group consisting of nitrogen, sulfur and oxygen;
• (d) Y is selected from the group consisting, independently or in combination, of saturated alkyl, unsaturated alkyl, unsubstituted aryl, substituted aryl, ether, carboxylic acid, carboxylic ester, secondary amine and sulfur;
• and
• (e) Z is a fluorophore, wherein a negative, thermo-neutral or slightly positive free energy value is obtained from the Rehm-Weller equation for the compound.