A compound of formula, or a salt thereof, wherein A is a reporter moiety, wherein the reporter moiety comprises a bioluminescent reporter moiety comprising a substrate for a luciferase, wherein the substrate is luciferin, a luciferin derivative or analog, a preluciferin or a preluciferin analog, a coelenterazine or a coelenterazine derivative or analog, or a fluorescent reporter moiety comprising a fluorophore selected from coumarin, R110, fluorescein, DDAO, resorufin, cresyl violet, silyl xanthene or carbopyronine; R 14 is H, alkyl, hydroxyalkyl, alkoxy, carboxyalkyl, or amidoalkyl; R 9 and R 10 are independently selected from alkyl; R 11, R 12 and R 13 are independently an alkyl; X is O; L is -(CH 2) m C(R 17) 2 (CH 2) n -Y-C -; R 17 is independently H, alkyl or both R 17 together can form an alkyl ring having from 3-7 carbons; m is an integer from 0-2; n is an integer from 0-2; Y is NR 15; R 15 is an -alkyl-amide, wherein the -alkyl-amide is - alkyl- -NR 34 -(CR a R b) p -NR 35 -T; R 34 and R 35 are each independently selected from hydrogen, and alkyl; R a and R b are each independently selected from hydrogen, alkyl, and carboxy; p is 0 to 6; and T is selected from aryl, arylalkyl, cycloalkylalkyl, heteroaryl, heteroarylalkyl, heterocycle, hydroxyalkyl, protein, polypeptide, polypeptide-based toxin, amino acid, nucleotide, polynucleotide, lipid, sugar, carbohydrate, drug, polymer-linked nanoparticle, antibody, detergent, and a dye, or a combination thereof; or R 15 is polyalkoxyalkyl, wherein the polyalkoxyalkyl is -(C 2 -C 6 -alkoxy) x -alkyl- -NR 34 -(CR a R b) p -NR 35 -T; x is an integer selected from 1 to 20; R 34 and R 35 are each independently selected from hydrogen, and alkyl; R a and R b are each independently selected from hydrogen, alkyl, and carboxy; p is 0 to 6; and T is selected from aryl, arylalkyl, cycloalkylalkyl, heteroaryl, heteroarylalkyl, heterocycle, hydroxyalkyl, protein, polypeptide, polypeptide-based toxin, amino acid, nucleotide, polynucleotide, lipid, sugar, carbohydrate, drug, polymer-linked nanoparticle, antibody, detergent, and a dye, or a combination thereof; or R 15 is wherein R 40 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, and cycloalkyl, wherein said aryl, heteroaryl, heterocyclyl, and cycloalkyl are unsubstituted or substituted with one or more suitable substituents; and x is an integer selected from 1 to 20. A is a reporter moiety, wherein the reporter moiety comprises a bioluminescent reporter moiety comprising a substrate for a luciferase, wherein the substrate is luciferin, a luciferin derivative or analog, a preluciferin or a preluciferin analog, a coelenterazine or a coelenterazine derivative or analog, or a fluorescent reporter moiety comprising a fluorophore selected from coumarin, R110, fluorescein, DDAO, resorufin, cresyl violet, silyl xanthene or carbopyronine; R 14 is H, alkyl, hydroxyalkyl, alkoxy, carboxyalkyl, or amidoalkyl; R 9 and R 10 are independently selected from alkyl; R 11, R 12 and R 13 are independently an alkyl; X is O; L is -(CH 2) m C(R 17) 2 (CH 2) n -Y-C -; R 17 is independently H, alkyl or both R 17 together can form an alkyl ring having from 3-7 carbons; m is an integer from 0-2; n is an integer from 0-2; Y is NR 15; R 15 is an -alkyl-amide, wherein the -alkyl-amide is - alkyl- -NR 34 -(CR a R b) p -NR 35 -T; R 34 and R 35 are each independently selected from hydrogen, and alkyl; R a and R b are each independently selected from hydrogen, alkyl, and carboxy; p is 0 to 6; and T is selected from aryl, arylalkyl, cycloalkylalkyl, heteroaryl, heteroarylalkyl, heterocycle, hydroxyalkyl, protein, polypeptide, polypeptide-based toxin, amino acid, nucleotide, polynucleotide, lipid, sugar, carbohydrate, drug, polymer-linked nanoparticle, antibody, detergent, and a dye, or a combination thereof; or R 15 is polyalkoxyalkyl, wherein the polyalkoxyalkyl is -(C 2 -C 6 -alkoxy) x -alkyl- -NR 34 -(CR a R b) p -NR 35 -T; x is an integer selected from 1 to 20; R 34 and R 35 are each independently selected from hydrogen, and alkyl; R a and R b are each independently selected from hydrogen, alkyl, and carboxy; p is 0 to 6; and T is selected from aryl, arylalkyl, cycloalkylalkyl, heteroaryl, heteroarylalkyl, heterocycle, hydroxyalkyl, protein, polypeptide, polypeptide-based toxin, amino acid, nucleotide, polynucleotide, lipid, sugar, carbohydrate, drug, polymer-linked nanoparticle, antibody, detergent, and a dye, or a combination thereof; or R 15 is wherein R 40 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, and cycloalkyl, wherein said aryl, heteroaryl, heterocyclyl, and cycloalkyl are unsubstituted or substituted with one or more suitable substituents; and x is an integer selected from 1 to 20.